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1 //===--- CGExpr.cpp - Emit LLVM Code from Expressions ---------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This contains code to emit Expr nodes as LLVM code.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "CGCXXABI.h"
15 #include "CGCall.h"
16 #include "CGCleanup.h"
17 #include "CGDebugInfo.h"
18 #include "CGObjCRuntime.h"
19 #include "CGOpenMPRuntime.h"
20 #include "CGRecordLayout.h"
21 #include "CodeGenFunction.h"
22 #include "CodeGenModule.h"
23 #include "TargetInfo.h"
24 #include "clang/AST/ASTContext.h"
25 #include "clang/AST/Attr.h"
26 #include "clang/AST/DeclObjC.h"
27 #include "clang/Frontend/CodeGenOptions.h"
28 #include "llvm/ADT/Hashing.h"
29 #include "llvm/ADT/StringExtras.h"
30 #include "llvm/IR/DataLayout.h"
31 #include "llvm/IR/Intrinsics.h"
32 #include "llvm/IR/LLVMContext.h"
33 #include "llvm/IR/MDBuilder.h"
34 #include "llvm/Support/ConvertUTF.h"
35 #include "llvm/Support/MathExtras.h"
36 #include "llvm/Support/Path.h"
37 #include "llvm/Transforms/Utils/SanitizerStats.h"
38 
39 using namespace clang;
40 using namespace CodeGen;
41 
42 //===--------------------------------------------------------------------===//
43 //                        Miscellaneous Helper Methods
44 //===--------------------------------------------------------------------===//
45 
EmitCastToVoidPtr(llvm::Value * value)46 llvm::Value *CodeGenFunction::EmitCastToVoidPtr(llvm::Value *value) {
47   unsigned addressSpace =
48     cast<llvm::PointerType>(value->getType())->getAddressSpace();
49 
50   llvm::PointerType *destType = Int8PtrTy;
51   if (addressSpace)
52     destType = llvm::Type::getInt8PtrTy(getLLVMContext(), addressSpace);
53 
54   if (value->getType() == destType) return value;
55   return Builder.CreateBitCast(value, destType);
56 }
57 
58 /// CreateTempAlloca - This creates a alloca and inserts it into the entry
59 /// block.
CreateTempAlloca(llvm::Type * Ty,CharUnits Align,const Twine & Name)60 Address CodeGenFunction::CreateTempAlloca(llvm::Type *Ty, CharUnits Align,
61                                           const Twine &Name) {
62   auto Alloca = CreateTempAlloca(Ty, Name);
63   Alloca->setAlignment(Align.getQuantity());
64   return Address(Alloca, Align);
65 }
66 
67 /// CreateTempAlloca - This creates a alloca and inserts it into the entry
68 /// block.
CreateTempAlloca(llvm::Type * Ty,const Twine & Name)69 llvm::AllocaInst *CodeGenFunction::CreateTempAlloca(llvm::Type *Ty,
70                                                     const Twine &Name) {
71   return new llvm::AllocaInst(Ty, nullptr, Name, AllocaInsertPt);
72 }
73 
74 /// CreateDefaultAlignTempAlloca - This creates an alloca with the
75 /// default alignment of the corresponding LLVM type, which is *not*
76 /// guaranteed to be related in any way to the expected alignment of
77 /// an AST type that might have been lowered to Ty.
CreateDefaultAlignTempAlloca(llvm::Type * Ty,const Twine & Name)78 Address CodeGenFunction::CreateDefaultAlignTempAlloca(llvm::Type *Ty,
79                                                       const Twine &Name) {
80   CharUnits Align =
81     CharUnits::fromQuantity(CGM.getDataLayout().getABITypeAlignment(Ty));
82   return CreateTempAlloca(Ty, Align, Name);
83 }
84 
InitTempAlloca(Address Var,llvm::Value * Init)85 void CodeGenFunction::InitTempAlloca(Address Var, llvm::Value *Init) {
86   assert(isa<llvm::AllocaInst>(Var.getPointer()));
87   auto *Store = new llvm::StoreInst(Init, Var.getPointer());
88   Store->setAlignment(Var.getAlignment().getQuantity());
89   llvm::BasicBlock *Block = AllocaInsertPt->getParent();
90   Block->getInstList().insertAfter(AllocaInsertPt->getIterator(), Store);
91 }
92 
CreateIRTemp(QualType Ty,const Twine & Name)93 Address CodeGenFunction::CreateIRTemp(QualType Ty, const Twine &Name) {
94   CharUnits Align = getContext().getTypeAlignInChars(Ty);
95   return CreateTempAlloca(ConvertType(Ty), Align, Name);
96 }
97 
CreateMemTemp(QualType Ty,const Twine & Name)98 Address CodeGenFunction::CreateMemTemp(QualType Ty, const Twine &Name) {
99   // FIXME: Should we prefer the preferred type alignment here?
100   return CreateMemTemp(Ty, getContext().getTypeAlignInChars(Ty), Name);
101 }
102 
CreateMemTemp(QualType Ty,CharUnits Align,const Twine & Name)103 Address CodeGenFunction::CreateMemTemp(QualType Ty, CharUnits Align,
104                                        const Twine &Name) {
105   return CreateTempAlloca(ConvertTypeForMem(Ty), Align, Name);
106 }
107 
108 /// EvaluateExprAsBool - Perform the usual unary conversions on the specified
109 /// expression and compare the result against zero, returning an Int1Ty value.
EvaluateExprAsBool(const Expr * E)110 llvm::Value *CodeGenFunction::EvaluateExprAsBool(const Expr *E) {
111   PGO.setCurrentStmt(E);
112   if (const MemberPointerType *MPT = E->getType()->getAs<MemberPointerType>()) {
113     llvm::Value *MemPtr = EmitScalarExpr(E);
114     return CGM.getCXXABI().EmitMemberPointerIsNotNull(*this, MemPtr, MPT);
115   }
116 
117   QualType BoolTy = getContext().BoolTy;
118   SourceLocation Loc = E->getExprLoc();
119   if (!E->getType()->isAnyComplexType())
120     return EmitScalarConversion(EmitScalarExpr(E), E->getType(), BoolTy, Loc);
121 
122   return EmitComplexToScalarConversion(EmitComplexExpr(E), E->getType(), BoolTy,
123                                        Loc);
124 }
125 
126 /// EmitIgnoredExpr - Emit code to compute the specified expression,
127 /// ignoring the result.
EmitIgnoredExpr(const Expr * E)128 void CodeGenFunction::EmitIgnoredExpr(const Expr *E) {
129   if (E->isRValue())
130     return (void) EmitAnyExpr(E, AggValueSlot::ignored(), true);
131 
132   // Just emit it as an l-value and drop the result.
133   EmitLValue(E);
134 }
135 
136 /// EmitAnyExpr - Emit code to compute the specified expression which
137 /// can have any type.  The result is returned as an RValue struct.
138 /// If this is an aggregate expression, AggSlot indicates where the
139 /// result should be returned.
EmitAnyExpr(const Expr * E,AggValueSlot aggSlot,bool ignoreResult)140 RValue CodeGenFunction::EmitAnyExpr(const Expr *E,
141                                     AggValueSlot aggSlot,
142                                     bool ignoreResult) {
143   switch (getEvaluationKind(E->getType())) {
144   case TEK_Scalar:
145     return RValue::get(EmitScalarExpr(E, ignoreResult));
146   case TEK_Complex:
147     return RValue::getComplex(EmitComplexExpr(E, ignoreResult, ignoreResult));
148   case TEK_Aggregate:
149     if (!ignoreResult && aggSlot.isIgnored())
150       aggSlot = CreateAggTemp(E->getType(), "agg-temp");
151     EmitAggExpr(E, aggSlot);
152     return aggSlot.asRValue();
153   }
154   llvm_unreachable("bad evaluation kind");
155 }
156 
157 /// EmitAnyExprToTemp - Similary to EmitAnyExpr(), however, the result will
158 /// always be accessible even if no aggregate location is provided.
EmitAnyExprToTemp(const Expr * E)159 RValue CodeGenFunction::EmitAnyExprToTemp(const Expr *E) {
160   AggValueSlot AggSlot = AggValueSlot::ignored();
161 
162   if (hasAggregateEvaluationKind(E->getType()))
163     AggSlot = CreateAggTemp(E->getType(), "agg.tmp");
164   return EmitAnyExpr(E, AggSlot);
165 }
166 
167 /// EmitAnyExprToMem - Evaluate an expression into a given memory
168 /// location.
EmitAnyExprToMem(const Expr * E,Address Location,Qualifiers Quals,bool IsInit)169 void CodeGenFunction::EmitAnyExprToMem(const Expr *E,
170                                        Address Location,
171                                        Qualifiers Quals,
172                                        bool IsInit) {
173   // FIXME: This function should take an LValue as an argument.
174   switch (getEvaluationKind(E->getType())) {
175   case TEK_Complex:
176     EmitComplexExprIntoLValue(E, MakeAddrLValue(Location, E->getType()),
177                               /*isInit*/ false);
178     return;
179 
180   case TEK_Aggregate: {
181     EmitAggExpr(E, AggValueSlot::forAddr(Location, Quals,
182                                          AggValueSlot::IsDestructed_t(IsInit),
183                                          AggValueSlot::DoesNotNeedGCBarriers,
184                                          AggValueSlot::IsAliased_t(!IsInit)));
185     return;
186   }
187 
188   case TEK_Scalar: {
189     RValue RV = RValue::get(EmitScalarExpr(E, /*Ignore*/ false));
190     LValue LV = MakeAddrLValue(Location, E->getType());
191     EmitStoreThroughLValue(RV, LV);
192     return;
193   }
194   }
195   llvm_unreachable("bad evaluation kind");
196 }
197 
198 static void
pushTemporaryCleanup(CodeGenFunction & CGF,const MaterializeTemporaryExpr * M,const Expr * E,Address ReferenceTemporary)199 pushTemporaryCleanup(CodeGenFunction &CGF, const MaterializeTemporaryExpr *M,
200                      const Expr *E, Address ReferenceTemporary) {
201   // Objective-C++ ARC:
202   //   If we are binding a reference to a temporary that has ownership, we
203   //   need to perform retain/release operations on the temporary.
204   //
205   // FIXME: This should be looking at E, not M.
206   if (auto Lifetime = M->getType().getObjCLifetime()) {
207     switch (Lifetime) {
208     case Qualifiers::OCL_None:
209     case Qualifiers::OCL_ExplicitNone:
210       // Carry on to normal cleanup handling.
211       break;
212 
213     case Qualifiers::OCL_Autoreleasing:
214       // Nothing to do; cleaned up by an autorelease pool.
215       return;
216 
217     case Qualifiers::OCL_Strong:
218     case Qualifiers::OCL_Weak:
219       switch (StorageDuration Duration = M->getStorageDuration()) {
220       case SD_Static:
221         // Note: we intentionally do not register a cleanup to release
222         // the object on program termination.
223         return;
224 
225       case SD_Thread:
226         // FIXME: We should probably register a cleanup in this case.
227         return;
228 
229       case SD_Automatic:
230       case SD_FullExpression:
231         CodeGenFunction::Destroyer *Destroy;
232         CleanupKind CleanupKind;
233         if (Lifetime == Qualifiers::OCL_Strong) {
234           const ValueDecl *VD = M->getExtendingDecl();
235           bool Precise =
236               VD && isa<VarDecl>(VD) && VD->hasAttr<ObjCPreciseLifetimeAttr>();
237           CleanupKind = CGF.getARCCleanupKind();
238           Destroy = Precise ? &CodeGenFunction::destroyARCStrongPrecise
239                             : &CodeGenFunction::destroyARCStrongImprecise;
240         } else {
241           // __weak objects always get EH cleanups; otherwise, exceptions
242           // could cause really nasty crashes instead of mere leaks.
243           CleanupKind = NormalAndEHCleanup;
244           Destroy = &CodeGenFunction::destroyARCWeak;
245         }
246         if (Duration == SD_FullExpression)
247           CGF.pushDestroy(CleanupKind, ReferenceTemporary,
248                           M->getType(), *Destroy,
249                           CleanupKind & EHCleanup);
250         else
251           CGF.pushLifetimeExtendedDestroy(CleanupKind, ReferenceTemporary,
252                                           M->getType(),
253                                           *Destroy, CleanupKind & EHCleanup);
254         return;
255 
256       case SD_Dynamic:
257         llvm_unreachable("temporary cannot have dynamic storage duration");
258       }
259       llvm_unreachable("unknown storage duration");
260     }
261   }
262 
263   CXXDestructorDecl *ReferenceTemporaryDtor = nullptr;
264   if (const RecordType *RT =
265           E->getType()->getBaseElementTypeUnsafe()->getAs<RecordType>()) {
266     // Get the destructor for the reference temporary.
267     auto *ClassDecl = cast<CXXRecordDecl>(RT->getDecl());
268     if (!ClassDecl->hasTrivialDestructor())
269       ReferenceTemporaryDtor = ClassDecl->getDestructor();
270   }
271 
272   if (!ReferenceTemporaryDtor)
273     return;
274 
275   // Call the destructor for the temporary.
276   switch (M->getStorageDuration()) {
277   case SD_Static:
278   case SD_Thread: {
279     llvm::Constant *CleanupFn;
280     llvm::Constant *CleanupArg;
281     if (E->getType()->isArrayType()) {
282       CleanupFn = CodeGenFunction(CGF.CGM).generateDestroyHelper(
283           ReferenceTemporary, E->getType(),
284           CodeGenFunction::destroyCXXObject, CGF.getLangOpts().Exceptions,
285           dyn_cast_or_null<VarDecl>(M->getExtendingDecl()));
286       CleanupArg = llvm::Constant::getNullValue(CGF.Int8PtrTy);
287     } else {
288       CleanupFn = CGF.CGM.getAddrOfCXXStructor(ReferenceTemporaryDtor,
289                                                StructorType::Complete);
290       CleanupArg = cast<llvm::Constant>(ReferenceTemporary.getPointer());
291     }
292     CGF.CGM.getCXXABI().registerGlobalDtor(
293         CGF, *cast<VarDecl>(M->getExtendingDecl()), CleanupFn, CleanupArg);
294     break;
295   }
296 
297   case SD_FullExpression:
298     CGF.pushDestroy(NormalAndEHCleanup, ReferenceTemporary, E->getType(),
299                     CodeGenFunction::destroyCXXObject,
300                     CGF.getLangOpts().Exceptions);
301     break;
302 
303   case SD_Automatic:
304     CGF.pushLifetimeExtendedDestroy(NormalAndEHCleanup,
305                                     ReferenceTemporary, E->getType(),
306                                     CodeGenFunction::destroyCXXObject,
307                                     CGF.getLangOpts().Exceptions);
308     break;
309 
310   case SD_Dynamic:
311     llvm_unreachable("temporary cannot have dynamic storage duration");
312   }
313 }
314 
315 static Address
createReferenceTemporary(CodeGenFunction & CGF,const MaterializeTemporaryExpr * M,const Expr * Inner)316 createReferenceTemporary(CodeGenFunction &CGF,
317                          const MaterializeTemporaryExpr *M, const Expr *Inner) {
318   switch (M->getStorageDuration()) {
319   case SD_FullExpression:
320   case SD_Automatic: {
321     // If we have a constant temporary array or record try to promote it into a
322     // constant global under the same rules a normal constant would've been
323     // promoted. This is easier on the optimizer and generally emits fewer
324     // instructions.
325     QualType Ty = Inner->getType();
326     if (CGF.CGM.getCodeGenOpts().MergeAllConstants &&
327         (Ty->isArrayType() || Ty->isRecordType()) &&
328         CGF.CGM.isTypeConstant(Ty, true))
329       if (llvm::Constant *Init = CGF.CGM.EmitConstantExpr(Inner, Ty, &CGF)) {
330         auto *GV = new llvm::GlobalVariable(
331             CGF.CGM.getModule(), Init->getType(), /*isConstant=*/true,
332             llvm::GlobalValue::PrivateLinkage, Init, ".ref.tmp");
333         CharUnits alignment = CGF.getContext().getTypeAlignInChars(Ty);
334         GV->setAlignment(alignment.getQuantity());
335         // FIXME: Should we put the new global into a COMDAT?
336         return Address(GV, alignment);
337       }
338     return CGF.CreateMemTemp(Ty, "ref.tmp");
339   }
340   case SD_Thread:
341   case SD_Static:
342     return CGF.CGM.GetAddrOfGlobalTemporary(M, Inner);
343 
344   case SD_Dynamic:
345     llvm_unreachable("temporary can't have dynamic storage duration");
346   }
347   llvm_unreachable("unknown storage duration");
348 }
349 
350 LValue CodeGenFunction::
EmitMaterializeTemporaryExpr(const MaterializeTemporaryExpr * M)351 EmitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *M) {
352   const Expr *E = M->GetTemporaryExpr();
353 
354     // FIXME: ideally this would use EmitAnyExprToMem, however, we cannot do so
355     // as that will cause the lifetime adjustment to be lost for ARC
356   auto ownership = M->getType().getObjCLifetime();
357   if (ownership != Qualifiers::OCL_None &&
358       ownership != Qualifiers::OCL_ExplicitNone) {
359     Address Object = createReferenceTemporary(*this, M, E);
360     if (auto *Var = dyn_cast<llvm::GlobalVariable>(Object.getPointer())) {
361       Object = Address(llvm::ConstantExpr::getBitCast(Var,
362                            ConvertTypeForMem(E->getType())
363                              ->getPointerTo(Object.getAddressSpace())),
364                        Object.getAlignment());
365 
366       // createReferenceTemporary will promote the temporary to a global with a
367       // constant initializer if it can.  It can only do this to a value of
368       // ARC-manageable type if the value is global and therefore "immune" to
369       // ref-counting operations.  Therefore we have no need to emit either a
370       // dynamic initialization or a cleanup and we can just return the address
371       // of the temporary.
372       if (Var->hasInitializer())
373         return MakeAddrLValue(Object, M->getType(), AlignmentSource::Decl);
374 
375       Var->setInitializer(CGM.EmitNullConstant(E->getType()));
376     }
377     LValue RefTempDst = MakeAddrLValue(Object, M->getType(),
378                                        AlignmentSource::Decl);
379 
380     switch (getEvaluationKind(E->getType())) {
381     default: llvm_unreachable("expected scalar or aggregate expression");
382     case TEK_Scalar:
383       EmitScalarInit(E, M->getExtendingDecl(), RefTempDst, false);
384       break;
385     case TEK_Aggregate: {
386       EmitAggExpr(E, AggValueSlot::forAddr(Object,
387                                            E->getType().getQualifiers(),
388                                            AggValueSlot::IsDestructed,
389                                            AggValueSlot::DoesNotNeedGCBarriers,
390                                            AggValueSlot::IsNotAliased));
391       break;
392     }
393     }
394 
395     pushTemporaryCleanup(*this, M, E, Object);
396     return RefTempDst;
397   }
398 
399   SmallVector<const Expr *, 2> CommaLHSs;
400   SmallVector<SubobjectAdjustment, 2> Adjustments;
401   E = E->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
402 
403   for (const auto &Ignored : CommaLHSs)
404     EmitIgnoredExpr(Ignored);
405 
406   if (const auto *opaque = dyn_cast<OpaqueValueExpr>(E)) {
407     if (opaque->getType()->isRecordType()) {
408       assert(Adjustments.empty());
409       return EmitOpaqueValueLValue(opaque);
410     }
411   }
412 
413   // Create and initialize the reference temporary.
414   Address Object = createReferenceTemporary(*this, M, E);
415   if (auto *Var = dyn_cast<llvm::GlobalVariable>(Object.getPointer())) {
416     Object = Address(llvm::ConstantExpr::getBitCast(
417         Var, ConvertTypeForMem(E->getType())->getPointerTo()),
418                      Object.getAlignment());
419     // If the temporary is a global and has a constant initializer or is a
420     // constant temporary that we promoted to a global, we may have already
421     // initialized it.
422     if (!Var->hasInitializer()) {
423       Var->setInitializer(CGM.EmitNullConstant(E->getType()));
424       EmitAnyExprToMem(E, Object, Qualifiers(), /*IsInit*/true);
425     }
426   } else {
427     switch (M->getStorageDuration()) {
428     case SD_Automatic:
429     case SD_FullExpression:
430       if (auto *Size = EmitLifetimeStart(
431               CGM.getDataLayout().getTypeAllocSize(Object.getElementType()),
432               Object.getPointer())) {
433         if (M->getStorageDuration() == SD_Automatic)
434           pushCleanupAfterFullExpr<CallLifetimeEnd>(NormalEHLifetimeMarker,
435                                                     Object, Size);
436         else
437           pushFullExprCleanup<CallLifetimeEnd>(NormalEHLifetimeMarker, Object,
438                                                Size);
439       }
440       break;
441     default:
442       break;
443     }
444     EmitAnyExprToMem(E, Object, Qualifiers(), /*IsInit*/true);
445   }
446   pushTemporaryCleanup(*this, M, E, Object);
447 
448   // Perform derived-to-base casts and/or field accesses, to get from the
449   // temporary object we created (and, potentially, for which we extended
450   // the lifetime) to the subobject we're binding the reference to.
451   for (unsigned I = Adjustments.size(); I != 0; --I) {
452     SubobjectAdjustment &Adjustment = Adjustments[I-1];
453     switch (Adjustment.Kind) {
454     case SubobjectAdjustment::DerivedToBaseAdjustment:
455       Object =
456           GetAddressOfBaseClass(Object, Adjustment.DerivedToBase.DerivedClass,
457                                 Adjustment.DerivedToBase.BasePath->path_begin(),
458                                 Adjustment.DerivedToBase.BasePath->path_end(),
459                                 /*NullCheckValue=*/ false, E->getExprLoc());
460       break;
461 
462     case SubobjectAdjustment::FieldAdjustment: {
463       LValue LV = MakeAddrLValue(Object, E->getType(),
464                                  AlignmentSource::Decl);
465       LV = EmitLValueForField(LV, Adjustment.Field);
466       assert(LV.isSimple() &&
467              "materialized temporary field is not a simple lvalue");
468       Object = LV.getAddress();
469       break;
470     }
471 
472     case SubobjectAdjustment::MemberPointerAdjustment: {
473       llvm::Value *Ptr = EmitScalarExpr(Adjustment.Ptr.RHS);
474       Object = EmitCXXMemberDataPointerAddress(E, Object, Ptr,
475                                                Adjustment.Ptr.MPT);
476       break;
477     }
478     }
479   }
480 
481   return MakeAddrLValue(Object, M->getType(), AlignmentSource::Decl);
482 }
483 
484 RValue
EmitReferenceBindingToExpr(const Expr * E)485 CodeGenFunction::EmitReferenceBindingToExpr(const Expr *E) {
486   // Emit the expression as an lvalue.
487   LValue LV = EmitLValue(E);
488   assert(LV.isSimple());
489   llvm::Value *Value = LV.getPointer();
490 
491   if (sanitizePerformTypeCheck() && !E->getType()->isFunctionType()) {
492     // C++11 [dcl.ref]p5 (as amended by core issue 453):
493     //   If a glvalue to which a reference is directly bound designates neither
494     //   an existing object or function of an appropriate type nor a region of
495     //   storage of suitable size and alignment to contain an object of the
496     //   reference's type, the behavior is undefined.
497     QualType Ty = E->getType();
498     EmitTypeCheck(TCK_ReferenceBinding, E->getExprLoc(), Value, Ty);
499   }
500 
501   return RValue::get(Value);
502 }
503 
504 
505 /// getAccessedFieldNo - Given an encoded value and a result number, return the
506 /// input field number being accessed.
getAccessedFieldNo(unsigned Idx,const llvm::Constant * Elts)507 unsigned CodeGenFunction::getAccessedFieldNo(unsigned Idx,
508                                              const llvm::Constant *Elts) {
509   return cast<llvm::ConstantInt>(Elts->getAggregateElement(Idx))
510       ->getZExtValue();
511 }
512 
513 /// Emit the hash_16_bytes function from include/llvm/ADT/Hashing.h.
emitHash16Bytes(CGBuilderTy & Builder,llvm::Value * Low,llvm::Value * High)514 static llvm::Value *emitHash16Bytes(CGBuilderTy &Builder, llvm::Value *Low,
515                                     llvm::Value *High) {
516   llvm::Value *KMul = Builder.getInt64(0x9ddfea08eb382d69ULL);
517   llvm::Value *K47 = Builder.getInt64(47);
518   llvm::Value *A0 = Builder.CreateMul(Builder.CreateXor(Low, High), KMul);
519   llvm::Value *A1 = Builder.CreateXor(Builder.CreateLShr(A0, K47), A0);
520   llvm::Value *B0 = Builder.CreateMul(Builder.CreateXor(High, A1), KMul);
521   llvm::Value *B1 = Builder.CreateXor(Builder.CreateLShr(B0, K47), B0);
522   return Builder.CreateMul(B1, KMul);
523 }
524 
sanitizePerformTypeCheck() const525 bool CodeGenFunction::sanitizePerformTypeCheck() const {
526   return SanOpts.has(SanitizerKind::Null) |
527          SanOpts.has(SanitizerKind::Alignment) |
528          SanOpts.has(SanitizerKind::ObjectSize) |
529          SanOpts.has(SanitizerKind::Vptr);
530 }
531 
EmitTypeCheck(TypeCheckKind TCK,SourceLocation Loc,llvm::Value * Ptr,QualType Ty,CharUnits Alignment,bool SkipNullCheck)532 void CodeGenFunction::EmitTypeCheck(TypeCheckKind TCK, SourceLocation Loc,
533                                     llvm::Value *Ptr, QualType Ty,
534                                     CharUnits Alignment, bool SkipNullCheck) {
535   if (!sanitizePerformTypeCheck())
536     return;
537 
538   // Don't check pointers outside the default address space. The null check
539   // isn't correct, the object-size check isn't supported by LLVM, and we can't
540   // communicate the addresses to the runtime handler for the vptr check.
541   if (Ptr->getType()->getPointerAddressSpace())
542     return;
543 
544   SanitizerScope SanScope(this);
545 
546   SmallVector<std::pair<llvm::Value *, SanitizerMask>, 3> Checks;
547   llvm::BasicBlock *Done = nullptr;
548 
549   bool AllowNullPointers = TCK == TCK_DowncastPointer || TCK == TCK_Upcast ||
550                            TCK == TCK_UpcastToVirtualBase;
551   if ((SanOpts.has(SanitizerKind::Null) || AllowNullPointers) &&
552       !SkipNullCheck) {
553     // The glvalue must not be an empty glvalue.
554     llvm::Value *IsNonNull = Builder.CreateIsNotNull(Ptr);
555 
556     if (AllowNullPointers) {
557       // When performing pointer casts, it's OK if the value is null.
558       // Skip the remaining checks in that case.
559       Done = createBasicBlock("null");
560       llvm::BasicBlock *Rest = createBasicBlock("not.null");
561       Builder.CreateCondBr(IsNonNull, Rest, Done);
562       EmitBlock(Rest);
563     } else {
564       Checks.push_back(std::make_pair(IsNonNull, SanitizerKind::Null));
565     }
566   }
567 
568   if (SanOpts.has(SanitizerKind::ObjectSize) && !Ty->isIncompleteType()) {
569     uint64_t Size = getContext().getTypeSizeInChars(Ty).getQuantity();
570 
571     // The glvalue must refer to a large enough storage region.
572     // FIXME: If Address Sanitizer is enabled, insert dynamic instrumentation
573     //        to check this.
574     // FIXME: Get object address space
575     llvm::Type *Tys[2] = { IntPtrTy, Int8PtrTy };
576     llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::objectsize, Tys);
577     llvm::Value *Min = Builder.getFalse();
578     llvm::Value *CastAddr = Builder.CreateBitCast(Ptr, Int8PtrTy);
579     llvm::Value *LargeEnough =
580         Builder.CreateICmpUGE(Builder.CreateCall(F, {CastAddr, Min}),
581                               llvm::ConstantInt::get(IntPtrTy, Size));
582     Checks.push_back(std::make_pair(LargeEnough, SanitizerKind::ObjectSize));
583   }
584 
585   uint64_t AlignVal = 0;
586 
587   if (SanOpts.has(SanitizerKind::Alignment)) {
588     AlignVal = Alignment.getQuantity();
589     if (!Ty->isIncompleteType() && !AlignVal)
590       AlignVal = getContext().getTypeAlignInChars(Ty).getQuantity();
591 
592     // The glvalue must be suitably aligned.
593     if (AlignVal) {
594       llvm::Value *Align =
595           Builder.CreateAnd(Builder.CreatePtrToInt(Ptr, IntPtrTy),
596                             llvm::ConstantInt::get(IntPtrTy, AlignVal - 1));
597       llvm::Value *Aligned =
598         Builder.CreateICmpEQ(Align, llvm::ConstantInt::get(IntPtrTy, 0));
599       Checks.push_back(std::make_pair(Aligned, SanitizerKind::Alignment));
600     }
601   }
602 
603   if (Checks.size() > 0) {
604     llvm::Constant *StaticData[] = {
605      EmitCheckSourceLocation(Loc),
606       EmitCheckTypeDescriptor(Ty),
607       llvm::ConstantInt::get(SizeTy, AlignVal),
608       llvm::ConstantInt::get(Int8Ty, TCK)
609     };
610     EmitCheck(Checks, "type_mismatch", StaticData, Ptr);
611   }
612 
613   // If possible, check that the vptr indicates that there is a subobject of
614   // type Ty at offset zero within this object.
615   //
616   // C++11 [basic.life]p5,6:
617   //   [For storage which does not refer to an object within its lifetime]
618   //   The program has undefined behavior if:
619   //    -- the [pointer or glvalue] is used to access a non-static data member
620   //       or call a non-static member function
621   CXXRecordDecl *RD = Ty->getAsCXXRecordDecl();
622   if (SanOpts.has(SanitizerKind::Vptr) &&
623       (TCK == TCK_MemberAccess || TCK == TCK_MemberCall ||
624        TCK == TCK_DowncastPointer || TCK == TCK_DowncastReference ||
625        TCK == TCK_UpcastToVirtualBase) &&
626       RD && RD->hasDefinition() && RD->isDynamicClass()) {
627     // Compute a hash of the mangled name of the type.
628     //
629     // FIXME: This is not guaranteed to be deterministic! Move to a
630     //        fingerprinting mechanism once LLVM provides one. For the time
631     //        being the implementation happens to be deterministic.
632     SmallString<64> MangledName;
633     llvm::raw_svector_ostream Out(MangledName);
634     CGM.getCXXABI().getMangleContext().mangleCXXRTTI(Ty.getUnqualifiedType(),
635                                                      Out);
636 
637     // Blacklist based on the mangled type.
638     if (!CGM.getContext().getSanitizerBlacklist().isBlacklistedType(
639             Out.str())) {
640       llvm::hash_code TypeHash = hash_value(Out.str());
641 
642       // Load the vptr, and compute hash_16_bytes(TypeHash, vptr).
643       llvm::Value *Low = llvm::ConstantInt::get(Int64Ty, TypeHash);
644       llvm::Type *VPtrTy = llvm::PointerType::get(IntPtrTy, 0);
645       Address VPtrAddr(Builder.CreateBitCast(Ptr, VPtrTy), getPointerAlign());
646       llvm::Value *VPtrVal = Builder.CreateLoad(VPtrAddr);
647       llvm::Value *High = Builder.CreateZExt(VPtrVal, Int64Ty);
648 
649       llvm::Value *Hash = emitHash16Bytes(Builder, Low, High);
650       Hash = Builder.CreateTrunc(Hash, IntPtrTy);
651 
652       // Look the hash up in our cache.
653       const int CacheSize = 128;
654       llvm::Type *HashTable = llvm::ArrayType::get(IntPtrTy, CacheSize);
655       llvm::Value *Cache = CGM.CreateRuntimeVariable(HashTable,
656                                                      "__ubsan_vptr_type_cache");
657       llvm::Value *Slot = Builder.CreateAnd(Hash,
658                                             llvm::ConstantInt::get(IntPtrTy,
659                                                                    CacheSize-1));
660       llvm::Value *Indices[] = { Builder.getInt32(0), Slot };
661       llvm::Value *CacheVal =
662         Builder.CreateAlignedLoad(Builder.CreateInBoundsGEP(Cache, Indices),
663                                   getPointerAlign());
664 
665       // If the hash isn't in the cache, call a runtime handler to perform the
666       // hard work of checking whether the vptr is for an object of the right
667       // type. This will either fill in the cache and return, or produce a
668       // diagnostic.
669       llvm::Value *EqualHash = Builder.CreateICmpEQ(CacheVal, Hash);
670       llvm::Constant *StaticData[] = {
671         EmitCheckSourceLocation(Loc),
672         EmitCheckTypeDescriptor(Ty),
673         CGM.GetAddrOfRTTIDescriptor(Ty.getUnqualifiedType()),
674         llvm::ConstantInt::get(Int8Ty, TCK)
675       };
676       llvm::Value *DynamicData[] = { Ptr, Hash };
677       EmitCheck(std::make_pair(EqualHash, SanitizerKind::Vptr),
678                 "dynamic_type_cache_miss", StaticData, DynamicData);
679     }
680   }
681 
682   if (Done) {
683     Builder.CreateBr(Done);
684     EmitBlock(Done);
685   }
686 }
687 
688 /// Determine whether this expression refers to a flexible array member in a
689 /// struct. We disable array bounds checks for such members.
isFlexibleArrayMemberExpr(const Expr * E)690 static bool isFlexibleArrayMemberExpr(const Expr *E) {
691   // For compatibility with existing code, we treat arrays of length 0 or
692   // 1 as flexible array members.
693   const ArrayType *AT = E->getType()->castAsArrayTypeUnsafe();
694   if (const auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
695     if (CAT->getSize().ugt(1))
696       return false;
697   } else if (!isa<IncompleteArrayType>(AT))
698     return false;
699 
700   E = E->IgnoreParens();
701 
702   // A flexible array member must be the last member in the class.
703   if (const auto *ME = dyn_cast<MemberExpr>(E)) {
704     // FIXME: If the base type of the member expr is not FD->getParent(),
705     // this should not be treated as a flexible array member access.
706     if (const auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl())) {
707       RecordDecl::field_iterator FI(
708           DeclContext::decl_iterator(const_cast<FieldDecl *>(FD)));
709       return ++FI == FD->getParent()->field_end();
710     }
711   }
712 
713   return false;
714 }
715 
716 /// If Base is known to point to the start of an array, return the length of
717 /// that array. Return 0 if the length cannot be determined.
getArrayIndexingBound(CodeGenFunction & CGF,const Expr * Base,QualType & IndexedType)718 static llvm::Value *getArrayIndexingBound(
719     CodeGenFunction &CGF, const Expr *Base, QualType &IndexedType) {
720   // For the vector indexing extension, the bound is the number of elements.
721   if (const VectorType *VT = Base->getType()->getAs<VectorType>()) {
722     IndexedType = Base->getType();
723     return CGF.Builder.getInt32(VT->getNumElements());
724   }
725 
726   Base = Base->IgnoreParens();
727 
728   if (const auto *CE = dyn_cast<CastExpr>(Base)) {
729     if (CE->getCastKind() == CK_ArrayToPointerDecay &&
730         !isFlexibleArrayMemberExpr(CE->getSubExpr())) {
731       IndexedType = CE->getSubExpr()->getType();
732       const ArrayType *AT = IndexedType->castAsArrayTypeUnsafe();
733       if (const auto *CAT = dyn_cast<ConstantArrayType>(AT))
734         return CGF.Builder.getInt(CAT->getSize());
735       else if (const auto *VAT = dyn_cast<VariableArrayType>(AT))
736         return CGF.getVLASize(VAT).first;
737     }
738   }
739 
740   return nullptr;
741 }
742 
EmitBoundsCheck(const Expr * E,const Expr * Base,llvm::Value * Index,QualType IndexType,bool Accessed)743 void CodeGenFunction::EmitBoundsCheck(const Expr *E, const Expr *Base,
744                                       llvm::Value *Index, QualType IndexType,
745                                       bool Accessed) {
746   assert(SanOpts.has(SanitizerKind::ArrayBounds) &&
747          "should not be called unless adding bounds checks");
748   SanitizerScope SanScope(this);
749 
750   QualType IndexedType;
751   llvm::Value *Bound = getArrayIndexingBound(*this, Base, IndexedType);
752   if (!Bound)
753     return;
754 
755   bool IndexSigned = IndexType->isSignedIntegerOrEnumerationType();
756   llvm::Value *IndexVal = Builder.CreateIntCast(Index, SizeTy, IndexSigned);
757   llvm::Value *BoundVal = Builder.CreateIntCast(Bound, SizeTy, false);
758 
759   llvm::Constant *StaticData[] = {
760     EmitCheckSourceLocation(E->getExprLoc()),
761     EmitCheckTypeDescriptor(IndexedType),
762     EmitCheckTypeDescriptor(IndexType)
763   };
764   llvm::Value *Check = Accessed ? Builder.CreateICmpULT(IndexVal, BoundVal)
765                                 : Builder.CreateICmpULE(IndexVal, BoundVal);
766   EmitCheck(std::make_pair(Check, SanitizerKind::ArrayBounds), "out_of_bounds",
767             StaticData, Index);
768 }
769 
770 
771 CodeGenFunction::ComplexPairTy CodeGenFunction::
EmitComplexPrePostIncDec(const UnaryOperator * E,LValue LV,bool isInc,bool isPre)772 EmitComplexPrePostIncDec(const UnaryOperator *E, LValue LV,
773                          bool isInc, bool isPre) {
774   ComplexPairTy InVal = EmitLoadOfComplex(LV, E->getExprLoc());
775 
776   llvm::Value *NextVal;
777   if (isa<llvm::IntegerType>(InVal.first->getType())) {
778     uint64_t AmountVal = isInc ? 1 : -1;
779     NextVal = llvm::ConstantInt::get(InVal.first->getType(), AmountVal, true);
780 
781     // Add the inc/dec to the real part.
782     NextVal = Builder.CreateAdd(InVal.first, NextVal, isInc ? "inc" : "dec");
783   } else {
784     QualType ElemTy = E->getType()->getAs<ComplexType>()->getElementType();
785     llvm::APFloat FVal(getContext().getFloatTypeSemantics(ElemTy), 1);
786     if (!isInc)
787       FVal.changeSign();
788     NextVal = llvm::ConstantFP::get(getLLVMContext(), FVal);
789 
790     // Add the inc/dec to the real part.
791     NextVal = Builder.CreateFAdd(InVal.first, NextVal, isInc ? "inc" : "dec");
792   }
793 
794   ComplexPairTy IncVal(NextVal, InVal.second);
795 
796   // Store the updated result through the lvalue.
797   EmitStoreOfComplex(IncVal, LV, /*init*/ false);
798 
799   // If this is a postinc, return the value read from memory, otherwise use the
800   // updated value.
801   return isPre ? IncVal : InVal;
802 }
803 
EmitExplicitCastExprType(const ExplicitCastExpr * E,CodeGenFunction * CGF)804 void CodeGenModule::EmitExplicitCastExprType(const ExplicitCastExpr *E,
805                                              CodeGenFunction *CGF) {
806   // Bind VLAs in the cast type.
807   if (CGF && E->getType()->isVariablyModifiedType())
808     CGF->EmitVariablyModifiedType(E->getType());
809 
810   if (CGDebugInfo *DI = getModuleDebugInfo())
811     DI->EmitExplicitCastType(E->getType());
812 }
813 
814 //===----------------------------------------------------------------------===//
815 //                         LValue Expression Emission
816 //===----------------------------------------------------------------------===//
817 
818 /// EmitPointerWithAlignment - Given an expression of pointer type, try to
819 /// derive a more accurate bound on the alignment of the pointer.
EmitPointerWithAlignment(const Expr * E,AlignmentSource * Source)820 Address CodeGenFunction::EmitPointerWithAlignment(const Expr *E,
821                                                   AlignmentSource  *Source) {
822   // We allow this with ObjC object pointers because of fragile ABIs.
823   assert(E->getType()->isPointerType() ||
824          E->getType()->isObjCObjectPointerType());
825   E = E->IgnoreParens();
826 
827   // Casts:
828   if (const CastExpr *CE = dyn_cast<CastExpr>(E)) {
829     if (const auto *ECE = dyn_cast<ExplicitCastExpr>(CE))
830       CGM.EmitExplicitCastExprType(ECE, this);
831 
832     switch (CE->getCastKind()) {
833     // Non-converting casts (but not C's implicit conversion from void*).
834     case CK_BitCast:
835     case CK_NoOp:
836       if (auto PtrTy = CE->getSubExpr()->getType()->getAs<PointerType>()) {
837         if (PtrTy->getPointeeType()->isVoidType())
838           break;
839 
840         AlignmentSource InnerSource;
841         Address Addr = EmitPointerWithAlignment(CE->getSubExpr(), &InnerSource);
842         if (Source) *Source = InnerSource;
843 
844         // If this is an explicit bitcast, and the source l-value is
845         // opaque, honor the alignment of the casted-to type.
846         if (isa<ExplicitCastExpr>(CE) &&
847             InnerSource != AlignmentSource::Decl) {
848           Addr = Address(Addr.getPointer(),
849                          getNaturalPointeeTypeAlignment(E->getType(), Source));
850         }
851 
852         if (SanOpts.has(SanitizerKind::CFIUnrelatedCast) &&
853             CE->getCastKind() == CK_BitCast) {
854           if (auto PT = E->getType()->getAs<PointerType>())
855             EmitVTablePtrCheckForCast(PT->getPointeeType(), Addr.getPointer(),
856                                       /*MayBeNull=*/true,
857                                       CodeGenFunction::CFITCK_UnrelatedCast,
858                                       CE->getLocStart());
859         }
860 
861         return Builder.CreateBitCast(Addr, ConvertType(E->getType()));
862       }
863       break;
864 
865     // Array-to-pointer decay.
866     case CK_ArrayToPointerDecay:
867       return EmitArrayToPointerDecay(CE->getSubExpr(), Source);
868 
869     // Derived-to-base conversions.
870     case CK_UncheckedDerivedToBase:
871     case CK_DerivedToBase: {
872       Address Addr = EmitPointerWithAlignment(CE->getSubExpr(), Source);
873       auto Derived = CE->getSubExpr()->getType()->getPointeeCXXRecordDecl();
874       return GetAddressOfBaseClass(Addr, Derived,
875                                    CE->path_begin(), CE->path_end(),
876                                    ShouldNullCheckClassCastValue(CE),
877                                    CE->getExprLoc());
878     }
879 
880     // TODO: Is there any reason to treat base-to-derived conversions
881     // specially?
882     default:
883       break;
884     }
885   }
886 
887   // Unary &.
888   if (const UnaryOperator *UO = dyn_cast<UnaryOperator>(E)) {
889     if (UO->getOpcode() == UO_AddrOf) {
890       LValue LV = EmitLValue(UO->getSubExpr());
891       if (Source) *Source = LV.getAlignmentSource();
892       return LV.getAddress();
893     }
894   }
895 
896   // TODO: conditional operators, comma.
897 
898   // Otherwise, use the alignment of the type.
899   CharUnits Align = getNaturalPointeeTypeAlignment(E->getType(), Source);
900   return Address(EmitScalarExpr(E), Align);
901 }
902 
GetUndefRValue(QualType Ty)903 RValue CodeGenFunction::GetUndefRValue(QualType Ty) {
904   if (Ty->isVoidType())
905     return RValue::get(nullptr);
906 
907   switch (getEvaluationKind(Ty)) {
908   case TEK_Complex: {
909     llvm::Type *EltTy =
910       ConvertType(Ty->castAs<ComplexType>()->getElementType());
911     llvm::Value *U = llvm::UndefValue::get(EltTy);
912     return RValue::getComplex(std::make_pair(U, U));
913   }
914 
915   // If this is a use of an undefined aggregate type, the aggregate must have an
916   // identifiable address.  Just because the contents of the value are undefined
917   // doesn't mean that the address can't be taken and compared.
918   case TEK_Aggregate: {
919     Address DestPtr = CreateMemTemp(Ty, "undef.agg.tmp");
920     return RValue::getAggregate(DestPtr);
921   }
922 
923   case TEK_Scalar:
924     return RValue::get(llvm::UndefValue::get(ConvertType(Ty)));
925   }
926   llvm_unreachable("bad evaluation kind");
927 }
928 
EmitUnsupportedRValue(const Expr * E,const char * Name)929 RValue CodeGenFunction::EmitUnsupportedRValue(const Expr *E,
930                                               const char *Name) {
931   ErrorUnsupported(E, Name);
932   return GetUndefRValue(E->getType());
933 }
934 
EmitUnsupportedLValue(const Expr * E,const char * Name)935 LValue CodeGenFunction::EmitUnsupportedLValue(const Expr *E,
936                                               const char *Name) {
937   ErrorUnsupported(E, Name);
938   llvm::Type *Ty = llvm::PointerType::getUnqual(ConvertType(E->getType()));
939   return MakeAddrLValue(Address(llvm::UndefValue::get(Ty), CharUnits::One()),
940                         E->getType());
941 }
942 
EmitCheckedLValue(const Expr * E,TypeCheckKind TCK)943 LValue CodeGenFunction::EmitCheckedLValue(const Expr *E, TypeCheckKind TCK) {
944   LValue LV;
945   if (SanOpts.has(SanitizerKind::ArrayBounds) && isa<ArraySubscriptExpr>(E))
946     LV = EmitArraySubscriptExpr(cast<ArraySubscriptExpr>(E), /*Accessed*/true);
947   else
948     LV = EmitLValue(E);
949   if (!isa<DeclRefExpr>(E) && !LV.isBitField() && LV.isSimple())
950     EmitTypeCheck(TCK, E->getExprLoc(), LV.getPointer(),
951                   E->getType(), LV.getAlignment());
952   return LV;
953 }
954 
955 /// EmitLValue - Emit code to compute a designator that specifies the location
956 /// of the expression.
957 ///
958 /// This can return one of two things: a simple address or a bitfield reference.
959 /// In either case, the LLVM Value* in the LValue structure is guaranteed to be
960 /// an LLVM pointer type.
961 ///
962 /// If this returns a bitfield reference, nothing about the pointee type of the
963 /// LLVM value is known: For example, it may not be a pointer to an integer.
964 ///
965 /// If this returns a normal address, and if the lvalue's C type is fixed size,
966 /// this method guarantees that the returned pointer type will point to an LLVM
967 /// type of the same size of the lvalue's type.  If the lvalue has a variable
968 /// length type, this is not possible.
969 ///
EmitLValue(const Expr * E)970 LValue CodeGenFunction::EmitLValue(const Expr *E) {
971   ApplyDebugLocation DL(*this, E);
972   switch (E->getStmtClass()) {
973   default: return EmitUnsupportedLValue(E, "l-value expression");
974 
975   case Expr::ObjCPropertyRefExprClass:
976     llvm_unreachable("cannot emit a property reference directly");
977 
978   case Expr::ObjCSelectorExprClass:
979     return EmitObjCSelectorLValue(cast<ObjCSelectorExpr>(E));
980   case Expr::ObjCIsaExprClass:
981     return EmitObjCIsaExpr(cast<ObjCIsaExpr>(E));
982   case Expr::BinaryOperatorClass:
983     return EmitBinaryOperatorLValue(cast<BinaryOperator>(E));
984   case Expr::CompoundAssignOperatorClass: {
985     QualType Ty = E->getType();
986     if (const AtomicType *AT = Ty->getAs<AtomicType>())
987       Ty = AT->getValueType();
988     if (!Ty->isAnyComplexType())
989       return EmitCompoundAssignmentLValue(cast<CompoundAssignOperator>(E));
990     return EmitComplexCompoundAssignmentLValue(cast<CompoundAssignOperator>(E));
991   }
992   case Expr::CallExprClass:
993   case Expr::CXXMemberCallExprClass:
994   case Expr::CXXOperatorCallExprClass:
995   case Expr::UserDefinedLiteralClass:
996     return EmitCallExprLValue(cast<CallExpr>(E));
997   case Expr::VAArgExprClass:
998     return EmitVAArgExprLValue(cast<VAArgExpr>(E));
999   case Expr::DeclRefExprClass:
1000     return EmitDeclRefLValue(cast<DeclRefExpr>(E));
1001   case Expr::ParenExprClass:
1002     return EmitLValue(cast<ParenExpr>(E)->getSubExpr());
1003   case Expr::GenericSelectionExprClass:
1004     return EmitLValue(cast<GenericSelectionExpr>(E)->getResultExpr());
1005   case Expr::PredefinedExprClass:
1006     return EmitPredefinedLValue(cast<PredefinedExpr>(E));
1007   case Expr::StringLiteralClass:
1008     return EmitStringLiteralLValue(cast<StringLiteral>(E));
1009   case Expr::ObjCEncodeExprClass:
1010     return EmitObjCEncodeExprLValue(cast<ObjCEncodeExpr>(E));
1011   case Expr::PseudoObjectExprClass:
1012     return EmitPseudoObjectLValue(cast<PseudoObjectExpr>(E));
1013   case Expr::InitListExprClass:
1014     return EmitInitListLValue(cast<InitListExpr>(E));
1015   case Expr::CXXTemporaryObjectExprClass:
1016   case Expr::CXXConstructExprClass:
1017     return EmitCXXConstructLValue(cast<CXXConstructExpr>(E));
1018   case Expr::CXXBindTemporaryExprClass:
1019     return EmitCXXBindTemporaryLValue(cast<CXXBindTemporaryExpr>(E));
1020   case Expr::CXXUuidofExprClass:
1021     return EmitCXXUuidofLValue(cast<CXXUuidofExpr>(E));
1022   case Expr::LambdaExprClass:
1023     return EmitLambdaLValue(cast<LambdaExpr>(E));
1024 
1025   case Expr::ExprWithCleanupsClass: {
1026     const auto *cleanups = cast<ExprWithCleanups>(E);
1027     enterFullExpression(cleanups);
1028     RunCleanupsScope Scope(*this);
1029     return EmitLValue(cleanups->getSubExpr());
1030   }
1031 
1032   case Expr::CXXDefaultArgExprClass:
1033     return EmitLValue(cast<CXXDefaultArgExpr>(E)->getExpr());
1034   case Expr::CXXDefaultInitExprClass: {
1035     CXXDefaultInitExprScope Scope(*this);
1036     return EmitLValue(cast<CXXDefaultInitExpr>(E)->getExpr());
1037   }
1038   case Expr::CXXTypeidExprClass:
1039     return EmitCXXTypeidLValue(cast<CXXTypeidExpr>(E));
1040 
1041   case Expr::ObjCMessageExprClass:
1042     return EmitObjCMessageExprLValue(cast<ObjCMessageExpr>(E));
1043   case Expr::ObjCIvarRefExprClass:
1044     return EmitObjCIvarRefLValue(cast<ObjCIvarRefExpr>(E));
1045   case Expr::StmtExprClass:
1046     return EmitStmtExprLValue(cast<StmtExpr>(E));
1047   case Expr::UnaryOperatorClass:
1048     return EmitUnaryOpLValue(cast<UnaryOperator>(E));
1049   case Expr::ArraySubscriptExprClass:
1050     return EmitArraySubscriptExpr(cast<ArraySubscriptExpr>(E));
1051   case Expr::OMPArraySectionExprClass:
1052     return EmitOMPArraySectionExpr(cast<OMPArraySectionExpr>(E));
1053   case Expr::ExtVectorElementExprClass:
1054     return EmitExtVectorElementExpr(cast<ExtVectorElementExpr>(E));
1055   case Expr::MemberExprClass:
1056     return EmitMemberExpr(cast<MemberExpr>(E));
1057   case Expr::CompoundLiteralExprClass:
1058     return EmitCompoundLiteralLValue(cast<CompoundLiteralExpr>(E));
1059   case Expr::ConditionalOperatorClass:
1060     return EmitConditionalOperatorLValue(cast<ConditionalOperator>(E));
1061   case Expr::BinaryConditionalOperatorClass:
1062     return EmitConditionalOperatorLValue(cast<BinaryConditionalOperator>(E));
1063   case Expr::ChooseExprClass:
1064     return EmitLValue(cast<ChooseExpr>(E)->getChosenSubExpr());
1065   case Expr::OpaqueValueExprClass:
1066     return EmitOpaqueValueLValue(cast<OpaqueValueExpr>(E));
1067   case Expr::SubstNonTypeTemplateParmExprClass:
1068     return EmitLValue(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement());
1069   case Expr::ImplicitCastExprClass:
1070   case Expr::CStyleCastExprClass:
1071   case Expr::CXXFunctionalCastExprClass:
1072   case Expr::CXXStaticCastExprClass:
1073   case Expr::CXXDynamicCastExprClass:
1074   case Expr::CXXReinterpretCastExprClass:
1075   case Expr::CXXConstCastExprClass:
1076   case Expr::ObjCBridgedCastExprClass:
1077     return EmitCastLValue(cast<CastExpr>(E));
1078 
1079   case Expr::MaterializeTemporaryExprClass:
1080     return EmitMaterializeTemporaryExpr(cast<MaterializeTemporaryExpr>(E));
1081   }
1082 }
1083 
1084 /// Given an object of the given canonical type, can we safely copy a
1085 /// value out of it based on its initializer?
isConstantEmittableObjectType(QualType type)1086 static bool isConstantEmittableObjectType(QualType type) {
1087   assert(type.isCanonical());
1088   assert(!type->isReferenceType());
1089 
1090   // Must be const-qualified but non-volatile.
1091   Qualifiers qs = type.getLocalQualifiers();
1092   if (!qs.hasConst() || qs.hasVolatile()) return false;
1093 
1094   // Otherwise, all object types satisfy this except C++ classes with
1095   // mutable subobjects or non-trivial copy/destroy behavior.
1096   if (const auto *RT = dyn_cast<RecordType>(type))
1097     if (const auto *RD = dyn_cast<CXXRecordDecl>(RT->getDecl()))
1098       if (RD->hasMutableFields() || !RD->isTrivial())
1099         return false;
1100 
1101   return true;
1102 }
1103 
1104 /// Can we constant-emit a load of a reference to a variable of the
1105 /// given type?  This is different from predicates like
1106 /// Decl::isUsableInConstantExpressions because we do want it to apply
1107 /// in situations that don't necessarily satisfy the language's rules
1108 /// for this (e.g. C++'s ODR-use rules).  For example, we want to able
1109 /// to do this with const float variables even if those variables
1110 /// aren't marked 'constexpr'.
1111 enum ConstantEmissionKind {
1112   CEK_None,
1113   CEK_AsReferenceOnly,
1114   CEK_AsValueOrReference,
1115   CEK_AsValueOnly
1116 };
checkVarTypeForConstantEmission(QualType type)1117 static ConstantEmissionKind checkVarTypeForConstantEmission(QualType type) {
1118   type = type.getCanonicalType();
1119   if (const auto *ref = dyn_cast<ReferenceType>(type)) {
1120     if (isConstantEmittableObjectType(ref->getPointeeType()))
1121       return CEK_AsValueOrReference;
1122     return CEK_AsReferenceOnly;
1123   }
1124   if (isConstantEmittableObjectType(type))
1125     return CEK_AsValueOnly;
1126   return CEK_None;
1127 }
1128 
1129 /// Try to emit a reference to the given value without producing it as
1130 /// an l-value.  This is actually more than an optimization: we can't
1131 /// produce an l-value for variables that we never actually captured
1132 /// in a block or lambda, which means const int variables or constexpr
1133 /// literals or similar.
1134 CodeGenFunction::ConstantEmission
tryEmitAsConstant(DeclRefExpr * refExpr)1135 CodeGenFunction::tryEmitAsConstant(DeclRefExpr *refExpr) {
1136   ValueDecl *value = refExpr->getDecl();
1137 
1138   // The value needs to be an enum constant or a constant variable.
1139   ConstantEmissionKind CEK;
1140   if (isa<ParmVarDecl>(value)) {
1141     CEK = CEK_None;
1142   } else if (auto *var = dyn_cast<VarDecl>(value)) {
1143     CEK = checkVarTypeForConstantEmission(var->getType());
1144   } else if (isa<EnumConstantDecl>(value)) {
1145     CEK = CEK_AsValueOnly;
1146   } else {
1147     CEK = CEK_None;
1148   }
1149   if (CEK == CEK_None) return ConstantEmission();
1150 
1151   Expr::EvalResult result;
1152   bool resultIsReference;
1153   QualType resultType;
1154 
1155   // It's best to evaluate all the way as an r-value if that's permitted.
1156   if (CEK != CEK_AsReferenceOnly &&
1157       refExpr->EvaluateAsRValue(result, getContext())) {
1158     resultIsReference = false;
1159     resultType = refExpr->getType();
1160 
1161   // Otherwise, try to evaluate as an l-value.
1162   } else if (CEK != CEK_AsValueOnly &&
1163              refExpr->EvaluateAsLValue(result, getContext())) {
1164     resultIsReference = true;
1165     resultType = value->getType();
1166 
1167   // Failure.
1168   } else {
1169     return ConstantEmission();
1170   }
1171 
1172   // In any case, if the initializer has side-effects, abandon ship.
1173   if (result.HasSideEffects)
1174     return ConstantEmission();
1175 
1176   // Emit as a constant.
1177   llvm::Constant *C = CGM.EmitConstantValue(result.Val, resultType, this);
1178 
1179   // Make sure we emit a debug reference to the global variable.
1180   // This should probably fire even for
1181   if (isa<VarDecl>(value)) {
1182     if (!getContext().DeclMustBeEmitted(cast<VarDecl>(value)))
1183       EmitDeclRefExprDbgValue(refExpr, C);
1184   } else {
1185     assert(isa<EnumConstantDecl>(value));
1186     EmitDeclRefExprDbgValue(refExpr, C);
1187   }
1188 
1189   // If we emitted a reference constant, we need to dereference that.
1190   if (resultIsReference)
1191     return ConstantEmission::forReference(C);
1192 
1193   return ConstantEmission::forValue(C);
1194 }
1195 
EmitLoadOfScalar(LValue lvalue,SourceLocation Loc)1196 llvm::Value *CodeGenFunction::EmitLoadOfScalar(LValue lvalue,
1197                                                SourceLocation Loc) {
1198   return EmitLoadOfScalar(lvalue.getAddress(), lvalue.isVolatile(),
1199                           lvalue.getType(), Loc, lvalue.getAlignmentSource(),
1200                           lvalue.getTBAAInfo(),
1201                           lvalue.getTBAABaseType(), lvalue.getTBAAOffset(),
1202                           lvalue.isNontemporal());
1203 }
1204 
hasBooleanRepresentation(QualType Ty)1205 static bool hasBooleanRepresentation(QualType Ty) {
1206   if (Ty->isBooleanType())
1207     return true;
1208 
1209   if (const EnumType *ET = Ty->getAs<EnumType>())
1210     return ET->getDecl()->getIntegerType()->isBooleanType();
1211 
1212   if (const AtomicType *AT = Ty->getAs<AtomicType>())
1213     return hasBooleanRepresentation(AT->getValueType());
1214 
1215   return false;
1216 }
1217 
getRangeForType(CodeGenFunction & CGF,QualType Ty,llvm::APInt & Min,llvm::APInt & End,bool StrictEnums)1218 static bool getRangeForType(CodeGenFunction &CGF, QualType Ty,
1219                             llvm::APInt &Min, llvm::APInt &End,
1220                             bool StrictEnums) {
1221   const EnumType *ET = Ty->getAs<EnumType>();
1222   bool IsRegularCPlusPlusEnum = CGF.getLangOpts().CPlusPlus && StrictEnums &&
1223                                 ET && !ET->getDecl()->isFixed();
1224   bool IsBool = hasBooleanRepresentation(Ty);
1225   if (!IsBool && !IsRegularCPlusPlusEnum)
1226     return false;
1227 
1228   if (IsBool) {
1229     Min = llvm::APInt(CGF.getContext().getTypeSize(Ty), 0);
1230     End = llvm::APInt(CGF.getContext().getTypeSize(Ty), 2);
1231   } else {
1232     const EnumDecl *ED = ET->getDecl();
1233     llvm::Type *LTy = CGF.ConvertTypeForMem(ED->getIntegerType());
1234     unsigned Bitwidth = LTy->getScalarSizeInBits();
1235     unsigned NumNegativeBits = ED->getNumNegativeBits();
1236     unsigned NumPositiveBits = ED->getNumPositiveBits();
1237 
1238     if (NumNegativeBits) {
1239       unsigned NumBits = std::max(NumNegativeBits, NumPositiveBits + 1);
1240       assert(NumBits <= Bitwidth);
1241       End = llvm::APInt(Bitwidth, 1) << (NumBits - 1);
1242       Min = -End;
1243     } else {
1244       assert(NumPositiveBits <= Bitwidth);
1245       End = llvm::APInt(Bitwidth, 1) << NumPositiveBits;
1246       Min = llvm::APInt(Bitwidth, 0);
1247     }
1248   }
1249   return true;
1250 }
1251 
getRangeForLoadFromType(QualType Ty)1252 llvm::MDNode *CodeGenFunction::getRangeForLoadFromType(QualType Ty) {
1253   llvm::APInt Min, End;
1254   if (!getRangeForType(*this, Ty, Min, End,
1255                        CGM.getCodeGenOpts().StrictEnums))
1256     return nullptr;
1257 
1258   llvm::MDBuilder MDHelper(getLLVMContext());
1259   return MDHelper.createRange(Min, End);
1260 }
1261 
EmitLoadOfScalar(Address Addr,bool Volatile,QualType Ty,SourceLocation Loc,AlignmentSource AlignSource,llvm::MDNode * TBAAInfo,QualType TBAABaseType,uint64_t TBAAOffset,bool isNontemporal)1262 llvm::Value *CodeGenFunction::EmitLoadOfScalar(Address Addr, bool Volatile,
1263                                                QualType Ty,
1264                                                SourceLocation Loc,
1265                                                AlignmentSource AlignSource,
1266                                                llvm::MDNode *TBAAInfo,
1267                                                QualType TBAABaseType,
1268                                                uint64_t TBAAOffset,
1269                                                bool isNontemporal) {
1270   // For better performance, handle vector loads differently.
1271   if (Ty->isVectorType()) {
1272     const llvm::Type *EltTy = Addr.getElementType();
1273 
1274     const auto *VTy = cast<llvm::VectorType>(EltTy);
1275 
1276     // Handle vectors of size 3 like size 4 for better performance.
1277     if (VTy->getNumElements() == 3) {
1278 
1279       // Bitcast to vec4 type.
1280       llvm::VectorType *vec4Ty = llvm::VectorType::get(VTy->getElementType(),
1281                                                          4);
1282       Address Cast = Builder.CreateElementBitCast(Addr, vec4Ty, "castToVec4");
1283       // Now load value.
1284       llvm::Value *V = Builder.CreateLoad(Cast, Volatile, "loadVec4");
1285 
1286       // Shuffle vector to get vec3.
1287       V = Builder.CreateShuffleVector(V, llvm::UndefValue::get(vec4Ty),
1288                                       {0, 1, 2}, "extractVec");
1289       return EmitFromMemory(V, Ty);
1290     }
1291   }
1292 
1293   // Atomic operations have to be done on integral types.
1294   LValue AtomicLValue =
1295       LValue::MakeAddr(Addr, Ty, getContext(), AlignSource, TBAAInfo);
1296   if (Ty->isAtomicType() || LValueIsSuitableForInlineAtomic(AtomicLValue)) {
1297     return EmitAtomicLoad(AtomicLValue, Loc).getScalarVal();
1298   }
1299 
1300   llvm::LoadInst *Load = Builder.CreateLoad(Addr, Volatile);
1301   if (isNontemporal) {
1302     llvm::MDNode *Node = llvm::MDNode::get(
1303         Load->getContext(), llvm::ConstantAsMetadata::get(Builder.getInt32(1)));
1304     Load->setMetadata(CGM.getModule().getMDKindID("nontemporal"), Node);
1305   }
1306   if (TBAAInfo) {
1307     llvm::MDNode *TBAAPath = CGM.getTBAAStructTagInfo(TBAABaseType, TBAAInfo,
1308                                                       TBAAOffset);
1309     if (TBAAPath)
1310       CGM.DecorateInstructionWithTBAA(Load, TBAAPath,
1311                                       false /*ConvertTypeToTag*/);
1312   }
1313 
1314   bool NeedsBoolCheck =
1315       SanOpts.has(SanitizerKind::Bool) && hasBooleanRepresentation(Ty);
1316   bool NeedsEnumCheck =
1317       SanOpts.has(SanitizerKind::Enum) && Ty->getAs<EnumType>();
1318   if (NeedsBoolCheck || NeedsEnumCheck) {
1319     SanitizerScope SanScope(this);
1320     llvm::APInt Min, End;
1321     if (getRangeForType(*this, Ty, Min, End, true)) {
1322       --End;
1323       llvm::Value *Check;
1324       if (!Min)
1325         Check = Builder.CreateICmpULE(
1326           Load, llvm::ConstantInt::get(getLLVMContext(), End));
1327       else {
1328         llvm::Value *Upper = Builder.CreateICmpSLE(
1329           Load, llvm::ConstantInt::get(getLLVMContext(), End));
1330         llvm::Value *Lower = Builder.CreateICmpSGE(
1331           Load, llvm::ConstantInt::get(getLLVMContext(), Min));
1332         Check = Builder.CreateAnd(Upper, Lower);
1333       }
1334       llvm::Constant *StaticArgs[] = {
1335         EmitCheckSourceLocation(Loc),
1336         EmitCheckTypeDescriptor(Ty)
1337       };
1338       SanitizerMask Kind = NeedsEnumCheck ? SanitizerKind::Enum : SanitizerKind::Bool;
1339       EmitCheck(std::make_pair(Check, Kind), "load_invalid_value", StaticArgs,
1340                 EmitCheckValue(Load));
1341     }
1342   } else if (CGM.getCodeGenOpts().OptimizationLevel > 0)
1343     if (llvm::MDNode *RangeInfo = getRangeForLoadFromType(Ty))
1344       Load->setMetadata(llvm::LLVMContext::MD_range, RangeInfo);
1345 
1346   return EmitFromMemory(Load, Ty);
1347 }
1348 
EmitToMemory(llvm::Value * Value,QualType Ty)1349 llvm::Value *CodeGenFunction::EmitToMemory(llvm::Value *Value, QualType Ty) {
1350   // Bool has a different representation in memory than in registers.
1351   if (hasBooleanRepresentation(Ty)) {
1352     // This should really always be an i1, but sometimes it's already
1353     // an i8, and it's awkward to track those cases down.
1354     if (Value->getType()->isIntegerTy(1))
1355       return Builder.CreateZExt(Value, ConvertTypeForMem(Ty), "frombool");
1356     assert(Value->getType()->isIntegerTy(getContext().getTypeSize(Ty)) &&
1357            "wrong value rep of bool");
1358   }
1359 
1360   return Value;
1361 }
1362 
EmitFromMemory(llvm::Value * Value,QualType Ty)1363 llvm::Value *CodeGenFunction::EmitFromMemory(llvm::Value *Value, QualType Ty) {
1364   // Bool has a different representation in memory than in registers.
1365   if (hasBooleanRepresentation(Ty)) {
1366     assert(Value->getType()->isIntegerTy(getContext().getTypeSize(Ty)) &&
1367            "wrong value rep of bool");
1368     return Builder.CreateTrunc(Value, Builder.getInt1Ty(), "tobool");
1369   }
1370 
1371   return Value;
1372 }
1373 
EmitStoreOfScalar(llvm::Value * Value,Address Addr,bool Volatile,QualType Ty,AlignmentSource AlignSource,llvm::MDNode * TBAAInfo,bool isInit,QualType TBAABaseType,uint64_t TBAAOffset,bool isNontemporal)1374 void CodeGenFunction::EmitStoreOfScalar(llvm::Value *Value, Address Addr,
1375                                         bool Volatile, QualType Ty,
1376                                         AlignmentSource AlignSource,
1377                                         llvm::MDNode *TBAAInfo,
1378                                         bool isInit, QualType TBAABaseType,
1379                                         uint64_t TBAAOffset,
1380                                         bool isNontemporal) {
1381 
1382   // Handle vectors differently to get better performance.
1383   if (Ty->isVectorType()) {
1384     llvm::Type *SrcTy = Value->getType();
1385     auto *VecTy = cast<llvm::VectorType>(SrcTy);
1386     // Handle vec3 special.
1387     if (VecTy->getNumElements() == 3) {
1388       // Our source is a vec3, do a shuffle vector to make it a vec4.
1389       llvm::Constant *Mask[] = {Builder.getInt32(0), Builder.getInt32(1),
1390                                 Builder.getInt32(2),
1391                                 llvm::UndefValue::get(Builder.getInt32Ty())};
1392       llvm::Value *MaskV = llvm::ConstantVector::get(Mask);
1393       Value = Builder.CreateShuffleVector(Value,
1394                                           llvm::UndefValue::get(VecTy),
1395                                           MaskV, "extractVec");
1396       SrcTy = llvm::VectorType::get(VecTy->getElementType(), 4);
1397     }
1398     if (Addr.getElementType() != SrcTy) {
1399       Addr = Builder.CreateElementBitCast(Addr, SrcTy, "storetmp");
1400     }
1401   }
1402 
1403   Value = EmitToMemory(Value, Ty);
1404 
1405   LValue AtomicLValue =
1406       LValue::MakeAddr(Addr, Ty, getContext(), AlignSource, TBAAInfo);
1407   if (Ty->isAtomicType() ||
1408       (!isInit && LValueIsSuitableForInlineAtomic(AtomicLValue))) {
1409     EmitAtomicStore(RValue::get(Value), AtomicLValue, isInit);
1410     return;
1411   }
1412 
1413   llvm::StoreInst *Store = Builder.CreateStore(Value, Addr, Volatile);
1414   if (isNontemporal) {
1415     llvm::MDNode *Node =
1416         llvm::MDNode::get(Store->getContext(),
1417                           llvm::ConstantAsMetadata::get(Builder.getInt32(1)));
1418     Store->setMetadata(CGM.getModule().getMDKindID("nontemporal"), Node);
1419   }
1420   if (TBAAInfo) {
1421     llvm::MDNode *TBAAPath = CGM.getTBAAStructTagInfo(TBAABaseType, TBAAInfo,
1422                                                       TBAAOffset);
1423     if (TBAAPath)
1424       CGM.DecorateInstructionWithTBAA(Store, TBAAPath,
1425                                       false /*ConvertTypeToTag*/);
1426   }
1427 }
1428 
EmitStoreOfScalar(llvm::Value * value,LValue lvalue,bool isInit)1429 void CodeGenFunction::EmitStoreOfScalar(llvm::Value *value, LValue lvalue,
1430                                         bool isInit) {
1431   EmitStoreOfScalar(value, lvalue.getAddress(), lvalue.isVolatile(),
1432                     lvalue.getType(), lvalue.getAlignmentSource(),
1433                     lvalue.getTBAAInfo(), isInit, lvalue.getTBAABaseType(),
1434                     lvalue.getTBAAOffset(), lvalue.isNontemporal());
1435 }
1436 
1437 /// EmitLoadOfLValue - Given an expression that represents a value lvalue, this
1438 /// method emits the address of the lvalue, then loads the result as an rvalue,
1439 /// returning the rvalue.
EmitLoadOfLValue(LValue LV,SourceLocation Loc)1440 RValue CodeGenFunction::EmitLoadOfLValue(LValue LV, SourceLocation Loc) {
1441   if (LV.isObjCWeak()) {
1442     // load of a __weak object.
1443     Address AddrWeakObj = LV.getAddress();
1444     return RValue::get(CGM.getObjCRuntime().EmitObjCWeakRead(*this,
1445                                                              AddrWeakObj));
1446   }
1447   if (LV.getQuals().getObjCLifetime() == Qualifiers::OCL_Weak) {
1448     // In MRC mode, we do a load+autorelease.
1449     if (!getLangOpts().ObjCAutoRefCount) {
1450       return RValue::get(EmitARCLoadWeak(LV.getAddress()));
1451     }
1452 
1453     // In ARC mode, we load retained and then consume the value.
1454     llvm::Value *Object = EmitARCLoadWeakRetained(LV.getAddress());
1455     Object = EmitObjCConsumeObject(LV.getType(), Object);
1456     return RValue::get(Object);
1457   }
1458 
1459   if (LV.isSimple()) {
1460     assert(!LV.getType()->isFunctionType());
1461 
1462     // Everything needs a load.
1463     return RValue::get(EmitLoadOfScalar(LV, Loc));
1464   }
1465 
1466   if (LV.isVectorElt()) {
1467     llvm::LoadInst *Load = Builder.CreateLoad(LV.getVectorAddress(),
1468                                               LV.isVolatileQualified());
1469     return RValue::get(Builder.CreateExtractElement(Load, LV.getVectorIdx(),
1470                                                     "vecext"));
1471   }
1472 
1473   // If this is a reference to a subset of the elements of a vector, either
1474   // shuffle the input or extract/insert them as appropriate.
1475   if (LV.isExtVectorElt())
1476     return EmitLoadOfExtVectorElementLValue(LV);
1477 
1478   // Global Register variables always invoke intrinsics
1479   if (LV.isGlobalReg())
1480     return EmitLoadOfGlobalRegLValue(LV);
1481 
1482   assert(LV.isBitField() && "Unknown LValue type!");
1483   return EmitLoadOfBitfieldLValue(LV);
1484 }
1485 
EmitLoadOfBitfieldLValue(LValue LV)1486 RValue CodeGenFunction::EmitLoadOfBitfieldLValue(LValue LV) {
1487   const CGBitFieldInfo &Info = LV.getBitFieldInfo();
1488 
1489   // Get the output type.
1490   llvm::Type *ResLTy = ConvertType(LV.getType());
1491 
1492   Address Ptr = LV.getBitFieldAddress();
1493   llvm::Value *Val = Builder.CreateLoad(Ptr, LV.isVolatileQualified(), "bf.load");
1494 
1495   if (Info.IsSigned) {
1496     assert(static_cast<unsigned>(Info.Offset + Info.Size) <= Info.StorageSize);
1497     unsigned HighBits = Info.StorageSize - Info.Offset - Info.Size;
1498     if (HighBits)
1499       Val = Builder.CreateShl(Val, HighBits, "bf.shl");
1500     if (Info.Offset + HighBits)
1501       Val = Builder.CreateAShr(Val, Info.Offset + HighBits, "bf.ashr");
1502   } else {
1503     if (Info.Offset)
1504       Val = Builder.CreateLShr(Val, Info.Offset, "bf.lshr");
1505     if (static_cast<unsigned>(Info.Offset) + Info.Size < Info.StorageSize)
1506       Val = Builder.CreateAnd(Val, llvm::APInt::getLowBitsSet(Info.StorageSize,
1507                                                               Info.Size),
1508                               "bf.clear");
1509   }
1510   Val = Builder.CreateIntCast(Val, ResLTy, Info.IsSigned, "bf.cast");
1511 
1512   return RValue::get(Val);
1513 }
1514 
1515 // If this is a reference to a subset of the elements of a vector, create an
1516 // appropriate shufflevector.
EmitLoadOfExtVectorElementLValue(LValue LV)1517 RValue CodeGenFunction::EmitLoadOfExtVectorElementLValue(LValue LV) {
1518   llvm::Value *Vec = Builder.CreateLoad(LV.getExtVectorAddress(),
1519                                         LV.isVolatileQualified());
1520 
1521   const llvm::Constant *Elts = LV.getExtVectorElts();
1522 
1523   // If the result of the expression is a non-vector type, we must be extracting
1524   // a single element.  Just codegen as an extractelement.
1525   const VectorType *ExprVT = LV.getType()->getAs<VectorType>();
1526   if (!ExprVT) {
1527     unsigned InIdx = getAccessedFieldNo(0, Elts);
1528     llvm::Value *Elt = llvm::ConstantInt::get(SizeTy, InIdx);
1529     return RValue::get(Builder.CreateExtractElement(Vec, Elt));
1530   }
1531 
1532   // Always use shuffle vector to try to retain the original program structure
1533   unsigned NumResultElts = ExprVT->getNumElements();
1534 
1535   SmallVector<llvm::Constant*, 4> Mask;
1536   for (unsigned i = 0; i != NumResultElts; ++i)
1537     Mask.push_back(Builder.getInt32(getAccessedFieldNo(i, Elts)));
1538 
1539   llvm::Value *MaskV = llvm::ConstantVector::get(Mask);
1540   Vec = Builder.CreateShuffleVector(Vec, llvm::UndefValue::get(Vec->getType()),
1541                                     MaskV);
1542   return RValue::get(Vec);
1543 }
1544 
1545 /// @brief Generates lvalue for partial ext_vector access.
EmitExtVectorElementLValue(LValue LV)1546 Address CodeGenFunction::EmitExtVectorElementLValue(LValue LV) {
1547   Address VectorAddress = LV.getExtVectorAddress();
1548   const VectorType *ExprVT = LV.getType()->getAs<VectorType>();
1549   QualType EQT = ExprVT->getElementType();
1550   llvm::Type *VectorElementTy = CGM.getTypes().ConvertType(EQT);
1551 
1552   Address CastToPointerElement =
1553     Builder.CreateElementBitCast(VectorAddress, VectorElementTy,
1554                                  "conv.ptr.element");
1555 
1556   const llvm::Constant *Elts = LV.getExtVectorElts();
1557   unsigned ix = getAccessedFieldNo(0, Elts);
1558 
1559   Address VectorBasePtrPlusIx =
1560     Builder.CreateConstInBoundsGEP(CastToPointerElement, ix,
1561                                    getContext().getTypeSizeInChars(EQT),
1562                                    "vector.elt");
1563 
1564   return VectorBasePtrPlusIx;
1565 }
1566 
1567 /// @brief Load of global gamed gegisters are always calls to intrinsics.
EmitLoadOfGlobalRegLValue(LValue LV)1568 RValue CodeGenFunction::EmitLoadOfGlobalRegLValue(LValue LV) {
1569   assert((LV.getType()->isIntegerType() || LV.getType()->isPointerType()) &&
1570          "Bad type for register variable");
1571   llvm::MDNode *RegName = cast<llvm::MDNode>(
1572       cast<llvm::MetadataAsValue>(LV.getGlobalReg())->getMetadata());
1573 
1574   // We accept integer and pointer types only
1575   llvm::Type *OrigTy = CGM.getTypes().ConvertType(LV.getType());
1576   llvm::Type *Ty = OrigTy;
1577   if (OrigTy->isPointerTy())
1578     Ty = CGM.getTypes().getDataLayout().getIntPtrType(OrigTy);
1579   llvm::Type *Types[] = { Ty };
1580 
1581   llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::read_register, Types);
1582   llvm::Value *Call = Builder.CreateCall(
1583       F, llvm::MetadataAsValue::get(Ty->getContext(), RegName));
1584   if (OrigTy->isPointerTy())
1585     Call = Builder.CreateIntToPtr(Call, OrigTy);
1586   return RValue::get(Call);
1587 }
1588 
1589 
1590 /// EmitStoreThroughLValue - Store the specified rvalue into the specified
1591 /// lvalue, where both are guaranteed to the have the same type, and that type
1592 /// is 'Ty'.
EmitStoreThroughLValue(RValue Src,LValue Dst,bool isInit)1593 void CodeGenFunction::EmitStoreThroughLValue(RValue Src, LValue Dst,
1594                                              bool isInit) {
1595   if (!Dst.isSimple()) {
1596     if (Dst.isVectorElt()) {
1597       // Read/modify/write the vector, inserting the new element.
1598       llvm::Value *Vec = Builder.CreateLoad(Dst.getVectorAddress(),
1599                                             Dst.isVolatileQualified());
1600       Vec = Builder.CreateInsertElement(Vec, Src.getScalarVal(),
1601                                         Dst.getVectorIdx(), "vecins");
1602       Builder.CreateStore(Vec, Dst.getVectorAddress(),
1603                           Dst.isVolatileQualified());
1604       return;
1605     }
1606 
1607     // If this is an update of extended vector elements, insert them as
1608     // appropriate.
1609     if (Dst.isExtVectorElt())
1610       return EmitStoreThroughExtVectorComponentLValue(Src, Dst);
1611 
1612     if (Dst.isGlobalReg())
1613       return EmitStoreThroughGlobalRegLValue(Src, Dst);
1614 
1615     assert(Dst.isBitField() && "Unknown LValue type");
1616     return EmitStoreThroughBitfieldLValue(Src, Dst);
1617   }
1618 
1619   // There's special magic for assigning into an ARC-qualified l-value.
1620   if (Qualifiers::ObjCLifetime Lifetime = Dst.getQuals().getObjCLifetime()) {
1621     switch (Lifetime) {
1622     case Qualifiers::OCL_None:
1623       llvm_unreachable("present but none");
1624 
1625     case Qualifiers::OCL_ExplicitNone:
1626       // nothing special
1627       break;
1628 
1629     case Qualifiers::OCL_Strong:
1630       EmitARCStoreStrong(Dst, Src.getScalarVal(), /*ignore*/ true);
1631       return;
1632 
1633     case Qualifiers::OCL_Weak:
1634       EmitARCStoreWeak(Dst.getAddress(), Src.getScalarVal(), /*ignore*/ true);
1635       return;
1636 
1637     case Qualifiers::OCL_Autoreleasing:
1638       Src = RValue::get(EmitObjCExtendObjectLifetime(Dst.getType(),
1639                                                      Src.getScalarVal()));
1640       // fall into the normal path
1641       break;
1642     }
1643   }
1644 
1645   if (Dst.isObjCWeak() && !Dst.isNonGC()) {
1646     // load of a __weak object.
1647     Address LvalueDst = Dst.getAddress();
1648     llvm::Value *src = Src.getScalarVal();
1649      CGM.getObjCRuntime().EmitObjCWeakAssign(*this, src, LvalueDst);
1650     return;
1651   }
1652 
1653   if (Dst.isObjCStrong() && !Dst.isNonGC()) {
1654     // load of a __strong object.
1655     Address LvalueDst = Dst.getAddress();
1656     llvm::Value *src = Src.getScalarVal();
1657     if (Dst.isObjCIvar()) {
1658       assert(Dst.getBaseIvarExp() && "BaseIvarExp is NULL");
1659       llvm::Type *ResultType = IntPtrTy;
1660       Address dst = EmitPointerWithAlignment(Dst.getBaseIvarExp());
1661       llvm::Value *RHS = dst.getPointer();
1662       RHS = Builder.CreatePtrToInt(RHS, ResultType, "sub.ptr.rhs.cast");
1663       llvm::Value *LHS =
1664         Builder.CreatePtrToInt(LvalueDst.getPointer(), ResultType,
1665                                "sub.ptr.lhs.cast");
1666       llvm::Value *BytesBetween = Builder.CreateSub(LHS, RHS, "ivar.offset");
1667       CGM.getObjCRuntime().EmitObjCIvarAssign(*this, src, dst,
1668                                               BytesBetween);
1669     } else if (Dst.isGlobalObjCRef()) {
1670       CGM.getObjCRuntime().EmitObjCGlobalAssign(*this, src, LvalueDst,
1671                                                 Dst.isThreadLocalRef());
1672     }
1673     else
1674       CGM.getObjCRuntime().EmitObjCStrongCastAssign(*this, src, LvalueDst);
1675     return;
1676   }
1677 
1678   assert(Src.isScalar() && "Can't emit an agg store with this method");
1679   EmitStoreOfScalar(Src.getScalarVal(), Dst, isInit);
1680 }
1681 
EmitStoreThroughBitfieldLValue(RValue Src,LValue Dst,llvm::Value ** Result)1682 void CodeGenFunction::EmitStoreThroughBitfieldLValue(RValue Src, LValue Dst,
1683                                                      llvm::Value **Result) {
1684   const CGBitFieldInfo &Info = Dst.getBitFieldInfo();
1685   llvm::Type *ResLTy = ConvertTypeForMem(Dst.getType());
1686   Address Ptr = Dst.getBitFieldAddress();
1687 
1688   // Get the source value, truncated to the width of the bit-field.
1689   llvm::Value *SrcVal = Src.getScalarVal();
1690 
1691   // Cast the source to the storage type and shift it into place.
1692   SrcVal = Builder.CreateIntCast(SrcVal, Ptr.getElementType(),
1693                                  /*IsSigned=*/false);
1694   llvm::Value *MaskedVal = SrcVal;
1695 
1696   // See if there are other bits in the bitfield's storage we'll need to load
1697   // and mask together with source before storing.
1698   if (Info.StorageSize != Info.Size) {
1699     assert(Info.StorageSize > Info.Size && "Invalid bitfield size.");
1700     llvm::Value *Val =
1701       Builder.CreateLoad(Ptr, Dst.isVolatileQualified(), "bf.load");
1702 
1703     // Mask the source value as needed.
1704     if (!hasBooleanRepresentation(Dst.getType()))
1705       SrcVal = Builder.CreateAnd(SrcVal,
1706                                  llvm::APInt::getLowBitsSet(Info.StorageSize,
1707                                                             Info.Size),
1708                                  "bf.value");
1709     MaskedVal = SrcVal;
1710     if (Info.Offset)
1711       SrcVal = Builder.CreateShl(SrcVal, Info.Offset, "bf.shl");
1712 
1713     // Mask out the original value.
1714     Val = Builder.CreateAnd(Val,
1715                             ~llvm::APInt::getBitsSet(Info.StorageSize,
1716                                                      Info.Offset,
1717                                                      Info.Offset + Info.Size),
1718                             "bf.clear");
1719 
1720     // Or together the unchanged values and the source value.
1721     SrcVal = Builder.CreateOr(Val, SrcVal, "bf.set");
1722   } else {
1723     assert(Info.Offset == 0);
1724   }
1725 
1726   // Write the new value back out.
1727   Builder.CreateStore(SrcVal, Ptr, Dst.isVolatileQualified());
1728 
1729   // Return the new value of the bit-field, if requested.
1730   if (Result) {
1731     llvm::Value *ResultVal = MaskedVal;
1732 
1733     // Sign extend the value if needed.
1734     if (Info.IsSigned) {
1735       assert(Info.Size <= Info.StorageSize);
1736       unsigned HighBits = Info.StorageSize - Info.Size;
1737       if (HighBits) {
1738         ResultVal = Builder.CreateShl(ResultVal, HighBits, "bf.result.shl");
1739         ResultVal = Builder.CreateAShr(ResultVal, HighBits, "bf.result.ashr");
1740       }
1741     }
1742 
1743     ResultVal = Builder.CreateIntCast(ResultVal, ResLTy, Info.IsSigned,
1744                                       "bf.result.cast");
1745     *Result = EmitFromMemory(ResultVal, Dst.getType());
1746   }
1747 }
1748 
EmitStoreThroughExtVectorComponentLValue(RValue Src,LValue Dst)1749 void CodeGenFunction::EmitStoreThroughExtVectorComponentLValue(RValue Src,
1750                                                                LValue Dst) {
1751   // This access turns into a read/modify/write of the vector.  Load the input
1752   // value now.
1753   llvm::Value *Vec = Builder.CreateLoad(Dst.getExtVectorAddress(),
1754                                         Dst.isVolatileQualified());
1755   const llvm::Constant *Elts = Dst.getExtVectorElts();
1756 
1757   llvm::Value *SrcVal = Src.getScalarVal();
1758 
1759   if (const VectorType *VTy = Dst.getType()->getAs<VectorType>()) {
1760     unsigned NumSrcElts = VTy->getNumElements();
1761     unsigned NumDstElts = Vec->getType()->getVectorNumElements();
1762     if (NumDstElts == NumSrcElts) {
1763       // Use shuffle vector is the src and destination are the same number of
1764       // elements and restore the vector mask since it is on the side it will be
1765       // stored.
1766       SmallVector<llvm::Constant*, 4> Mask(NumDstElts);
1767       for (unsigned i = 0; i != NumSrcElts; ++i)
1768         Mask[getAccessedFieldNo(i, Elts)] = Builder.getInt32(i);
1769 
1770       llvm::Value *MaskV = llvm::ConstantVector::get(Mask);
1771       Vec = Builder.CreateShuffleVector(SrcVal,
1772                                         llvm::UndefValue::get(Vec->getType()),
1773                                         MaskV);
1774     } else if (NumDstElts > NumSrcElts) {
1775       // Extended the source vector to the same length and then shuffle it
1776       // into the destination.
1777       // FIXME: since we're shuffling with undef, can we just use the indices
1778       //        into that?  This could be simpler.
1779       SmallVector<llvm::Constant*, 4> ExtMask;
1780       for (unsigned i = 0; i != NumSrcElts; ++i)
1781         ExtMask.push_back(Builder.getInt32(i));
1782       ExtMask.resize(NumDstElts, llvm::UndefValue::get(Int32Ty));
1783       llvm::Value *ExtMaskV = llvm::ConstantVector::get(ExtMask);
1784       llvm::Value *ExtSrcVal =
1785         Builder.CreateShuffleVector(SrcVal,
1786                                     llvm::UndefValue::get(SrcVal->getType()),
1787                                     ExtMaskV);
1788       // build identity
1789       SmallVector<llvm::Constant*, 4> Mask;
1790       for (unsigned i = 0; i != NumDstElts; ++i)
1791         Mask.push_back(Builder.getInt32(i));
1792 
1793       // When the vector size is odd and .odd or .hi is used, the last element
1794       // of the Elts constant array will be one past the size of the vector.
1795       // Ignore the last element here, if it is greater than the mask size.
1796       if (getAccessedFieldNo(NumSrcElts - 1, Elts) == Mask.size())
1797         NumSrcElts--;
1798 
1799       // modify when what gets shuffled in
1800       for (unsigned i = 0; i != NumSrcElts; ++i)
1801         Mask[getAccessedFieldNo(i, Elts)] = Builder.getInt32(i+NumDstElts);
1802       llvm::Value *MaskV = llvm::ConstantVector::get(Mask);
1803       Vec = Builder.CreateShuffleVector(Vec, ExtSrcVal, MaskV);
1804     } else {
1805       // We should never shorten the vector
1806       llvm_unreachable("unexpected shorten vector length");
1807     }
1808   } else {
1809     // If the Src is a scalar (not a vector) it must be updating one element.
1810     unsigned InIdx = getAccessedFieldNo(0, Elts);
1811     llvm::Value *Elt = llvm::ConstantInt::get(SizeTy, InIdx);
1812     Vec = Builder.CreateInsertElement(Vec, SrcVal, Elt);
1813   }
1814 
1815   Builder.CreateStore(Vec, Dst.getExtVectorAddress(),
1816                       Dst.isVolatileQualified());
1817 }
1818 
1819 /// @brief Store of global named registers are always calls to intrinsics.
EmitStoreThroughGlobalRegLValue(RValue Src,LValue Dst)1820 void CodeGenFunction::EmitStoreThroughGlobalRegLValue(RValue Src, LValue Dst) {
1821   assert((Dst.getType()->isIntegerType() || Dst.getType()->isPointerType()) &&
1822          "Bad type for register variable");
1823   llvm::MDNode *RegName = cast<llvm::MDNode>(
1824       cast<llvm::MetadataAsValue>(Dst.getGlobalReg())->getMetadata());
1825   assert(RegName && "Register LValue is not metadata");
1826 
1827   // We accept integer and pointer types only
1828   llvm::Type *OrigTy = CGM.getTypes().ConvertType(Dst.getType());
1829   llvm::Type *Ty = OrigTy;
1830   if (OrigTy->isPointerTy())
1831     Ty = CGM.getTypes().getDataLayout().getIntPtrType(OrigTy);
1832   llvm::Type *Types[] = { Ty };
1833 
1834   llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::write_register, Types);
1835   llvm::Value *Value = Src.getScalarVal();
1836   if (OrigTy->isPointerTy())
1837     Value = Builder.CreatePtrToInt(Value, Ty);
1838   Builder.CreateCall(
1839       F, {llvm::MetadataAsValue::get(Ty->getContext(), RegName), Value});
1840 }
1841 
1842 // setObjCGCLValueClass - sets class of the lvalue for the purpose of
1843 // generating write-barries API. It is currently a global, ivar,
1844 // or neither.
setObjCGCLValueClass(const ASTContext & Ctx,const Expr * E,LValue & LV,bool IsMemberAccess=false)1845 static void setObjCGCLValueClass(const ASTContext &Ctx, const Expr *E,
1846                                  LValue &LV,
1847                                  bool IsMemberAccess=false) {
1848   if (Ctx.getLangOpts().getGC() == LangOptions::NonGC)
1849     return;
1850 
1851   if (isa<ObjCIvarRefExpr>(E)) {
1852     QualType ExpTy = E->getType();
1853     if (IsMemberAccess && ExpTy->isPointerType()) {
1854       // If ivar is a structure pointer, assigning to field of
1855       // this struct follows gcc's behavior and makes it a non-ivar
1856       // writer-barrier conservatively.
1857       ExpTy = ExpTy->getAs<PointerType>()->getPointeeType();
1858       if (ExpTy->isRecordType()) {
1859         LV.setObjCIvar(false);
1860         return;
1861       }
1862     }
1863     LV.setObjCIvar(true);
1864     auto *Exp = cast<ObjCIvarRefExpr>(const_cast<Expr *>(E));
1865     LV.setBaseIvarExp(Exp->getBase());
1866     LV.setObjCArray(E->getType()->isArrayType());
1867     return;
1868   }
1869 
1870   if (const auto *Exp = dyn_cast<DeclRefExpr>(E)) {
1871     if (const auto *VD = dyn_cast<VarDecl>(Exp->getDecl())) {
1872       if (VD->hasGlobalStorage()) {
1873         LV.setGlobalObjCRef(true);
1874         LV.setThreadLocalRef(VD->getTLSKind() != VarDecl::TLS_None);
1875       }
1876     }
1877     LV.setObjCArray(E->getType()->isArrayType());
1878     return;
1879   }
1880 
1881   if (const auto *Exp = dyn_cast<UnaryOperator>(E)) {
1882     setObjCGCLValueClass(Ctx, Exp->getSubExpr(), LV, IsMemberAccess);
1883     return;
1884   }
1885 
1886   if (const auto *Exp = dyn_cast<ParenExpr>(E)) {
1887     setObjCGCLValueClass(Ctx, Exp->getSubExpr(), LV, IsMemberAccess);
1888     if (LV.isObjCIvar()) {
1889       // If cast is to a structure pointer, follow gcc's behavior and make it
1890       // a non-ivar write-barrier.
1891       QualType ExpTy = E->getType();
1892       if (ExpTy->isPointerType())
1893         ExpTy = ExpTy->getAs<PointerType>()->getPointeeType();
1894       if (ExpTy->isRecordType())
1895         LV.setObjCIvar(false);
1896     }
1897     return;
1898   }
1899 
1900   if (const auto *Exp = dyn_cast<GenericSelectionExpr>(E)) {
1901     setObjCGCLValueClass(Ctx, Exp->getResultExpr(), LV);
1902     return;
1903   }
1904 
1905   if (const auto *Exp = dyn_cast<ImplicitCastExpr>(E)) {
1906     setObjCGCLValueClass(Ctx, Exp->getSubExpr(), LV, IsMemberAccess);
1907     return;
1908   }
1909 
1910   if (const auto *Exp = dyn_cast<CStyleCastExpr>(E)) {
1911     setObjCGCLValueClass(Ctx, Exp->getSubExpr(), LV, IsMemberAccess);
1912     return;
1913   }
1914 
1915   if (const auto *Exp = dyn_cast<ObjCBridgedCastExpr>(E)) {
1916     setObjCGCLValueClass(Ctx, Exp->getSubExpr(), LV, IsMemberAccess);
1917     return;
1918   }
1919 
1920   if (const auto *Exp = dyn_cast<ArraySubscriptExpr>(E)) {
1921     setObjCGCLValueClass(Ctx, Exp->getBase(), LV);
1922     if (LV.isObjCIvar() && !LV.isObjCArray())
1923       // Using array syntax to assigning to what an ivar points to is not
1924       // same as assigning to the ivar itself. {id *Names;} Names[i] = 0;
1925       LV.setObjCIvar(false);
1926     else if (LV.isGlobalObjCRef() && !LV.isObjCArray())
1927       // Using array syntax to assigning to what global points to is not
1928       // same as assigning to the global itself. {id *G;} G[i] = 0;
1929       LV.setGlobalObjCRef(false);
1930     return;
1931   }
1932 
1933   if (const auto *Exp = dyn_cast<MemberExpr>(E)) {
1934     setObjCGCLValueClass(Ctx, Exp->getBase(), LV, true);
1935     // We don't know if member is an 'ivar', but this flag is looked at
1936     // only in the context of LV.isObjCIvar().
1937     LV.setObjCArray(E->getType()->isArrayType());
1938     return;
1939   }
1940 }
1941 
1942 static llvm::Value *
EmitBitCastOfLValueToProperType(CodeGenFunction & CGF,llvm::Value * V,llvm::Type * IRType,StringRef Name=StringRef ())1943 EmitBitCastOfLValueToProperType(CodeGenFunction &CGF,
1944                                 llvm::Value *V, llvm::Type *IRType,
1945                                 StringRef Name = StringRef()) {
1946   unsigned AS = cast<llvm::PointerType>(V->getType())->getAddressSpace();
1947   return CGF.Builder.CreateBitCast(V, IRType->getPointerTo(AS), Name);
1948 }
1949 
EmitThreadPrivateVarDeclLValue(CodeGenFunction & CGF,const VarDecl * VD,QualType T,Address Addr,llvm::Type * RealVarTy,SourceLocation Loc)1950 static LValue EmitThreadPrivateVarDeclLValue(
1951     CodeGenFunction &CGF, const VarDecl *VD, QualType T, Address Addr,
1952     llvm::Type *RealVarTy, SourceLocation Loc) {
1953   Addr = CGF.CGM.getOpenMPRuntime().getAddrOfThreadPrivate(CGF, VD, Addr, Loc);
1954   Addr = CGF.Builder.CreateElementBitCast(Addr, RealVarTy);
1955   return CGF.MakeAddrLValue(Addr, T, AlignmentSource::Decl);
1956 }
1957 
EmitLoadOfReference(Address Addr,const ReferenceType * RefTy,AlignmentSource * Source)1958 Address CodeGenFunction::EmitLoadOfReference(Address Addr,
1959                                              const ReferenceType *RefTy,
1960                                              AlignmentSource *Source) {
1961   llvm::Value *Ptr = Builder.CreateLoad(Addr);
1962   return Address(Ptr, getNaturalTypeAlignment(RefTy->getPointeeType(),
1963                                               Source, /*forPointee*/ true));
1964 
1965 }
1966 
EmitLoadOfReferenceLValue(Address RefAddr,const ReferenceType * RefTy)1967 LValue CodeGenFunction::EmitLoadOfReferenceLValue(Address RefAddr,
1968                                                   const ReferenceType *RefTy) {
1969   AlignmentSource Source;
1970   Address Addr = EmitLoadOfReference(RefAddr, RefTy, &Source);
1971   return MakeAddrLValue(Addr, RefTy->getPointeeType(), Source);
1972 }
1973 
EmitLoadOfPointer(Address Ptr,const PointerType * PtrTy,AlignmentSource * Source)1974 Address CodeGenFunction::EmitLoadOfPointer(Address Ptr,
1975                                            const PointerType *PtrTy,
1976                                            AlignmentSource *Source) {
1977   llvm::Value *Addr = Builder.CreateLoad(Ptr);
1978   return Address(Addr, getNaturalTypeAlignment(PtrTy->getPointeeType(), Source,
1979                                                /*forPointeeType=*/true));
1980 }
1981 
EmitLoadOfPointerLValue(Address PtrAddr,const PointerType * PtrTy)1982 LValue CodeGenFunction::EmitLoadOfPointerLValue(Address PtrAddr,
1983                                                 const PointerType *PtrTy) {
1984   AlignmentSource Source;
1985   Address Addr = EmitLoadOfPointer(PtrAddr, PtrTy, &Source);
1986   return MakeAddrLValue(Addr, PtrTy->getPointeeType(), Source);
1987 }
1988 
EmitGlobalVarDeclLValue(CodeGenFunction & CGF,const Expr * E,const VarDecl * VD)1989 static LValue EmitGlobalVarDeclLValue(CodeGenFunction &CGF,
1990                                       const Expr *E, const VarDecl *VD) {
1991   QualType T = E->getType();
1992 
1993   // If it's thread_local, emit a call to its wrapper function instead.
1994   if (VD->getTLSKind() == VarDecl::TLS_Dynamic &&
1995       CGF.CGM.getCXXABI().usesThreadWrapperFunction())
1996     return CGF.CGM.getCXXABI().EmitThreadLocalVarDeclLValue(CGF, VD, T);
1997 
1998   llvm::Value *V = CGF.CGM.GetAddrOfGlobalVar(VD);
1999   llvm::Type *RealVarTy = CGF.getTypes().ConvertTypeForMem(VD->getType());
2000   V = EmitBitCastOfLValueToProperType(CGF, V, RealVarTy);
2001   CharUnits Alignment = CGF.getContext().getDeclAlign(VD);
2002   Address Addr(V, Alignment);
2003   LValue LV;
2004   // Emit reference to the private copy of the variable if it is an OpenMP
2005   // threadprivate variable.
2006   if (CGF.getLangOpts().OpenMP && VD->hasAttr<OMPThreadPrivateDeclAttr>())
2007     return EmitThreadPrivateVarDeclLValue(CGF, VD, T, Addr, RealVarTy,
2008                                           E->getExprLoc());
2009   if (auto RefTy = VD->getType()->getAs<ReferenceType>()) {
2010     LV = CGF.EmitLoadOfReferenceLValue(Addr, RefTy);
2011   } else {
2012     LV = CGF.MakeAddrLValue(Addr, T, AlignmentSource::Decl);
2013   }
2014   setObjCGCLValueClass(CGF.getContext(), E, LV);
2015   return LV;
2016 }
2017 
EmitFunctionDeclLValue(CodeGenFunction & CGF,const Expr * E,const FunctionDecl * FD)2018 static LValue EmitFunctionDeclLValue(CodeGenFunction &CGF,
2019                                      const Expr *E, const FunctionDecl *FD) {
2020   llvm::Value *V = CGF.CGM.GetAddrOfFunction(FD);
2021   if (!FD->hasPrototype()) {
2022     if (const FunctionProtoType *Proto =
2023             FD->getType()->getAs<FunctionProtoType>()) {
2024       // Ugly case: for a K&R-style definition, the type of the definition
2025       // isn't the same as the type of a use.  Correct for this with a
2026       // bitcast.
2027       QualType NoProtoType =
2028           CGF.getContext().getFunctionNoProtoType(Proto->getReturnType());
2029       NoProtoType = CGF.getContext().getPointerType(NoProtoType);
2030       V = CGF.Builder.CreateBitCast(V, CGF.ConvertType(NoProtoType));
2031     }
2032   }
2033   CharUnits Alignment = CGF.getContext().getDeclAlign(FD);
2034   return CGF.MakeAddrLValue(V, E->getType(), Alignment, AlignmentSource::Decl);
2035 }
2036 
EmitCapturedFieldLValue(CodeGenFunction & CGF,const FieldDecl * FD,llvm::Value * ThisValue)2037 static LValue EmitCapturedFieldLValue(CodeGenFunction &CGF, const FieldDecl *FD,
2038                                       llvm::Value *ThisValue) {
2039   QualType TagType = CGF.getContext().getTagDeclType(FD->getParent());
2040   LValue LV = CGF.MakeNaturalAlignAddrLValue(ThisValue, TagType);
2041   return CGF.EmitLValueForField(LV, FD);
2042 }
2043 
2044 /// Named Registers are named metadata pointing to the register name
2045 /// which will be read from/written to as an argument to the intrinsic
2046 /// @llvm.read/write_register.
2047 /// So far, only the name is being passed down, but other options such as
2048 /// register type, allocation type or even optimization options could be
2049 /// passed down via the metadata node.
EmitGlobalNamedRegister(const VarDecl * VD,CodeGenModule & CGM)2050 static LValue EmitGlobalNamedRegister(const VarDecl *VD, CodeGenModule &CGM) {
2051   SmallString<64> Name("llvm.named.register.");
2052   AsmLabelAttr *Asm = VD->getAttr<AsmLabelAttr>();
2053   assert(Asm->getLabel().size() < 64-Name.size() &&
2054       "Register name too big");
2055   Name.append(Asm->getLabel());
2056   llvm::NamedMDNode *M =
2057     CGM.getModule().getOrInsertNamedMetadata(Name);
2058   if (M->getNumOperands() == 0) {
2059     llvm::MDString *Str = llvm::MDString::get(CGM.getLLVMContext(),
2060                                               Asm->getLabel());
2061     llvm::Metadata *Ops[] = {Str};
2062     M->addOperand(llvm::MDNode::get(CGM.getLLVMContext(), Ops));
2063   }
2064 
2065   CharUnits Alignment = CGM.getContext().getDeclAlign(VD);
2066 
2067   llvm::Value *Ptr =
2068     llvm::MetadataAsValue::get(CGM.getLLVMContext(), M->getOperand(0));
2069   return LValue::MakeGlobalReg(Address(Ptr, Alignment), VD->getType());
2070 }
2071 
EmitDeclRefLValue(const DeclRefExpr * E)2072 LValue CodeGenFunction::EmitDeclRefLValue(const DeclRefExpr *E) {
2073   const NamedDecl *ND = E->getDecl();
2074   QualType T = E->getType();
2075 
2076   if (const auto *VD = dyn_cast<VarDecl>(ND)) {
2077     // Global Named registers access via intrinsics only
2078     if (VD->getStorageClass() == SC_Register &&
2079         VD->hasAttr<AsmLabelAttr>() && !VD->isLocalVarDecl())
2080       return EmitGlobalNamedRegister(VD, CGM);
2081 
2082     // A DeclRefExpr for a reference initialized by a constant expression can
2083     // appear without being odr-used. Directly emit the constant initializer.
2084     const Expr *Init = VD->getAnyInitializer(VD);
2085     if (Init && !isa<ParmVarDecl>(VD) && VD->getType()->isReferenceType() &&
2086         VD->isUsableInConstantExpressions(getContext()) &&
2087         VD->checkInitIsICE() &&
2088         // Do not emit if it is private OpenMP variable.
2089         !(E->refersToEnclosingVariableOrCapture() && CapturedStmtInfo &&
2090           LocalDeclMap.count(VD))) {
2091       llvm::Constant *Val =
2092         CGM.EmitConstantValue(*VD->evaluateValue(), VD->getType(), this);
2093       assert(Val && "failed to emit reference constant expression");
2094       // FIXME: Eventually we will want to emit vector element references.
2095 
2096       // Should we be using the alignment of the constant pointer we emitted?
2097       CharUnits Alignment = getNaturalTypeAlignment(E->getType(), nullptr,
2098                                                     /*pointee*/ true);
2099 
2100       return MakeAddrLValue(Address(Val, Alignment), T, AlignmentSource::Decl);
2101     }
2102 
2103     // Check for captured variables.
2104     if (E->refersToEnclosingVariableOrCapture()) {
2105       if (auto *FD = LambdaCaptureFields.lookup(VD))
2106         return EmitCapturedFieldLValue(*this, FD, CXXABIThisValue);
2107       else if (CapturedStmtInfo) {
2108         auto it = LocalDeclMap.find(VD);
2109         if (it != LocalDeclMap.end()) {
2110           if (auto RefTy = VD->getType()->getAs<ReferenceType>()) {
2111             return EmitLoadOfReferenceLValue(it->second, RefTy);
2112           }
2113           return MakeAddrLValue(it->second, T);
2114         }
2115         LValue CapLVal =
2116             EmitCapturedFieldLValue(*this, CapturedStmtInfo->lookup(VD),
2117                                     CapturedStmtInfo->getContextValue());
2118         return MakeAddrLValue(
2119             Address(CapLVal.getPointer(), getContext().getDeclAlign(VD)),
2120             CapLVal.getType(), AlignmentSource::Decl);
2121       }
2122 
2123       assert(isa<BlockDecl>(CurCodeDecl));
2124       Address addr = GetAddrOfBlockDecl(VD, VD->hasAttr<BlocksAttr>());
2125       return MakeAddrLValue(addr, T, AlignmentSource::Decl);
2126     }
2127   }
2128 
2129   // FIXME: We should be able to assert this for FunctionDecls as well!
2130   // FIXME: We should be able to assert this for all DeclRefExprs, not just
2131   // those with a valid source location.
2132   assert((ND->isUsed(false) || !isa<VarDecl>(ND) ||
2133           !E->getLocation().isValid()) &&
2134          "Should not use decl without marking it used!");
2135 
2136   if (ND->hasAttr<WeakRefAttr>()) {
2137     const auto *VD = cast<ValueDecl>(ND);
2138     ConstantAddress Aliasee = CGM.GetWeakRefReference(VD);
2139     return MakeAddrLValue(Aliasee, T, AlignmentSource::Decl);
2140   }
2141 
2142   if (const auto *VD = dyn_cast<VarDecl>(ND)) {
2143     // Check if this is a global variable.
2144     if (VD->hasLinkage() || VD->isStaticDataMember())
2145       return EmitGlobalVarDeclLValue(*this, E, VD);
2146 
2147     Address addr = Address::invalid();
2148 
2149     // The variable should generally be present in the local decl map.
2150     auto iter = LocalDeclMap.find(VD);
2151     if (iter != LocalDeclMap.end()) {
2152       addr = iter->second;
2153 
2154     // Otherwise, it might be static local we haven't emitted yet for
2155     // some reason; most likely, because it's in an outer function.
2156     } else if (VD->isStaticLocal()) {
2157       addr = Address(CGM.getOrCreateStaticVarDecl(
2158           *VD, CGM.getLLVMLinkageVarDefinition(VD, /*isConstant=*/false)),
2159                      getContext().getDeclAlign(VD));
2160 
2161     // No other cases for now.
2162     } else {
2163       llvm_unreachable("DeclRefExpr for Decl not entered in LocalDeclMap?");
2164     }
2165 
2166 
2167     // Check for OpenMP threadprivate variables.
2168     if (getLangOpts().OpenMP && VD->hasAttr<OMPThreadPrivateDeclAttr>()) {
2169       return EmitThreadPrivateVarDeclLValue(
2170           *this, VD, T, addr, getTypes().ConvertTypeForMem(VD->getType()),
2171           E->getExprLoc());
2172     }
2173 
2174     // Drill into block byref variables.
2175     bool isBlockByref = VD->hasAttr<BlocksAttr>();
2176     if (isBlockByref) {
2177       addr = emitBlockByrefAddress(addr, VD);
2178     }
2179 
2180     // Drill into reference types.
2181     LValue LV;
2182     if (auto RefTy = VD->getType()->getAs<ReferenceType>()) {
2183       LV = EmitLoadOfReferenceLValue(addr, RefTy);
2184     } else {
2185       LV = MakeAddrLValue(addr, T, AlignmentSource::Decl);
2186     }
2187 
2188     bool isLocalStorage = VD->hasLocalStorage();
2189 
2190     bool NonGCable = isLocalStorage &&
2191                      !VD->getType()->isReferenceType() &&
2192                      !isBlockByref;
2193     if (NonGCable) {
2194       LV.getQuals().removeObjCGCAttr();
2195       LV.setNonGC(true);
2196     }
2197 
2198     bool isImpreciseLifetime =
2199       (isLocalStorage && !VD->hasAttr<ObjCPreciseLifetimeAttr>());
2200     if (isImpreciseLifetime)
2201       LV.setARCPreciseLifetime(ARCImpreciseLifetime);
2202     setObjCGCLValueClass(getContext(), E, LV);
2203     return LV;
2204   }
2205 
2206   if (const auto *FD = dyn_cast<FunctionDecl>(ND))
2207     return EmitFunctionDeclLValue(*this, E, FD);
2208 
2209   llvm_unreachable("Unhandled DeclRefExpr");
2210 }
2211 
EmitUnaryOpLValue(const UnaryOperator * E)2212 LValue CodeGenFunction::EmitUnaryOpLValue(const UnaryOperator *E) {
2213   // __extension__ doesn't affect lvalue-ness.
2214   if (E->getOpcode() == UO_Extension)
2215     return EmitLValue(E->getSubExpr());
2216 
2217   QualType ExprTy = getContext().getCanonicalType(E->getSubExpr()->getType());
2218   switch (E->getOpcode()) {
2219   default: llvm_unreachable("Unknown unary operator lvalue!");
2220   case UO_Deref: {
2221     QualType T = E->getSubExpr()->getType()->getPointeeType();
2222     assert(!T.isNull() && "CodeGenFunction::EmitUnaryOpLValue: Illegal type");
2223 
2224     AlignmentSource AlignSource;
2225     Address Addr = EmitPointerWithAlignment(E->getSubExpr(), &AlignSource);
2226     LValue LV = MakeAddrLValue(Addr, T, AlignSource);
2227     LV.getQuals().setAddressSpace(ExprTy.getAddressSpace());
2228 
2229     // We should not generate __weak write barrier on indirect reference
2230     // of a pointer to object; as in void foo (__weak id *param); *param = 0;
2231     // But, we continue to generate __strong write barrier on indirect write
2232     // into a pointer to object.
2233     if (getLangOpts().ObjC1 &&
2234         getLangOpts().getGC() != LangOptions::NonGC &&
2235         LV.isObjCWeak())
2236       LV.setNonGC(!E->isOBJCGCCandidate(getContext()));
2237     return LV;
2238   }
2239   case UO_Real:
2240   case UO_Imag: {
2241     LValue LV = EmitLValue(E->getSubExpr());
2242     assert(LV.isSimple() && "real/imag on non-ordinary l-value");
2243 
2244     // __real is valid on scalars.  This is a faster way of testing that.
2245     // __imag can only produce an rvalue on scalars.
2246     if (E->getOpcode() == UO_Real &&
2247         !LV.getAddress().getElementType()->isStructTy()) {
2248       assert(E->getSubExpr()->getType()->isArithmeticType());
2249       return LV;
2250     }
2251 
2252     assert(E->getSubExpr()->getType()->isAnyComplexType());
2253 
2254     Address Component =
2255       (E->getOpcode() == UO_Real
2256          ? emitAddrOfRealComponent(LV.getAddress(), LV.getType())
2257          : emitAddrOfImagComponent(LV.getAddress(), LV.getType()));
2258     return MakeAddrLValue(Component, ExprTy, LV.getAlignmentSource());
2259   }
2260   case UO_PreInc:
2261   case UO_PreDec: {
2262     LValue LV = EmitLValue(E->getSubExpr());
2263     bool isInc = E->getOpcode() == UO_PreInc;
2264 
2265     if (E->getType()->isAnyComplexType())
2266       EmitComplexPrePostIncDec(E, LV, isInc, true/*isPre*/);
2267     else
2268       EmitScalarPrePostIncDec(E, LV, isInc, true/*isPre*/);
2269     return LV;
2270   }
2271   }
2272 }
2273 
EmitStringLiteralLValue(const StringLiteral * E)2274 LValue CodeGenFunction::EmitStringLiteralLValue(const StringLiteral *E) {
2275   return MakeAddrLValue(CGM.GetAddrOfConstantStringFromLiteral(E),
2276                         E->getType(), AlignmentSource::Decl);
2277 }
2278 
EmitObjCEncodeExprLValue(const ObjCEncodeExpr * E)2279 LValue CodeGenFunction::EmitObjCEncodeExprLValue(const ObjCEncodeExpr *E) {
2280   return MakeAddrLValue(CGM.GetAddrOfConstantStringFromObjCEncode(E),
2281                         E->getType(), AlignmentSource::Decl);
2282 }
2283 
EmitPredefinedLValue(const PredefinedExpr * E)2284 LValue CodeGenFunction::EmitPredefinedLValue(const PredefinedExpr *E) {
2285   auto SL = E->getFunctionName();
2286   assert(SL != nullptr && "No StringLiteral name in PredefinedExpr");
2287   StringRef FnName = CurFn->getName();
2288   if (FnName.startswith("\01"))
2289     FnName = FnName.substr(1);
2290   StringRef NameItems[] = {
2291       PredefinedExpr::getIdentTypeName(E->getIdentType()), FnName};
2292   std::string GVName = llvm::join(NameItems, NameItems + 2, ".");
2293   if (CurCodeDecl && isa<BlockDecl>(CurCodeDecl)) {
2294     auto C = CGM.GetAddrOfConstantCString(FnName, GVName.c_str());
2295     return MakeAddrLValue(C, E->getType(), AlignmentSource::Decl);
2296   }
2297   auto C = CGM.GetAddrOfConstantStringFromLiteral(SL, GVName);
2298   return MakeAddrLValue(C, E->getType(), AlignmentSource::Decl);
2299 }
2300 
2301 /// Emit a type description suitable for use by a runtime sanitizer library. The
2302 /// format of a type descriptor is
2303 ///
2304 /// \code
2305 ///   { i16 TypeKind, i16 TypeInfo }
2306 /// \endcode
2307 ///
2308 /// followed by an array of i8 containing the type name. TypeKind is 0 for an
2309 /// integer, 1 for a floating point value, and -1 for anything else.
EmitCheckTypeDescriptor(QualType T)2310 llvm::Constant *CodeGenFunction::EmitCheckTypeDescriptor(QualType T) {
2311   // Only emit each type's descriptor once.
2312   if (llvm::Constant *C = CGM.getTypeDescriptorFromMap(T))
2313     return C;
2314 
2315   uint16_t TypeKind = -1;
2316   uint16_t TypeInfo = 0;
2317 
2318   if (T->isIntegerType()) {
2319     TypeKind = 0;
2320     TypeInfo = (llvm::Log2_32(getContext().getTypeSize(T)) << 1) |
2321                (T->isSignedIntegerType() ? 1 : 0);
2322   } else if (T->isFloatingType()) {
2323     TypeKind = 1;
2324     TypeInfo = getContext().getTypeSize(T);
2325   }
2326 
2327   // Format the type name as if for a diagnostic, including quotes and
2328   // optionally an 'aka'.
2329   SmallString<32> Buffer;
2330   CGM.getDiags().ConvertArgToString(DiagnosticsEngine::ak_qualtype,
2331                                     (intptr_t)T.getAsOpaquePtr(),
2332                                     StringRef(), StringRef(), None, Buffer,
2333                                     None);
2334 
2335   llvm::Constant *Components[] = {
2336     Builder.getInt16(TypeKind), Builder.getInt16(TypeInfo),
2337     llvm::ConstantDataArray::getString(getLLVMContext(), Buffer)
2338   };
2339   llvm::Constant *Descriptor = llvm::ConstantStruct::getAnon(Components);
2340 
2341   auto *GV = new llvm::GlobalVariable(
2342       CGM.getModule(), Descriptor->getType(),
2343       /*isConstant=*/true, llvm::GlobalVariable::PrivateLinkage, Descriptor);
2344   GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
2345   CGM.getSanitizerMetadata()->disableSanitizerForGlobal(GV);
2346 
2347   // Remember the descriptor for this type.
2348   CGM.setTypeDescriptorInMap(T, GV);
2349 
2350   return GV;
2351 }
2352 
EmitCheckValue(llvm::Value * V)2353 llvm::Value *CodeGenFunction::EmitCheckValue(llvm::Value *V) {
2354   llvm::Type *TargetTy = IntPtrTy;
2355 
2356   // Floating-point types which fit into intptr_t are bitcast to integers
2357   // and then passed directly (after zero-extension, if necessary).
2358   if (V->getType()->isFloatingPointTy()) {
2359     unsigned Bits = V->getType()->getPrimitiveSizeInBits();
2360     if (Bits <= TargetTy->getIntegerBitWidth())
2361       V = Builder.CreateBitCast(V, llvm::Type::getIntNTy(getLLVMContext(),
2362                                                          Bits));
2363   }
2364 
2365   // Integers which fit in intptr_t are zero-extended and passed directly.
2366   if (V->getType()->isIntegerTy() &&
2367       V->getType()->getIntegerBitWidth() <= TargetTy->getIntegerBitWidth())
2368     return Builder.CreateZExt(V, TargetTy);
2369 
2370   // Pointers are passed directly, everything else is passed by address.
2371   if (!V->getType()->isPointerTy()) {
2372     Address Ptr = CreateDefaultAlignTempAlloca(V->getType());
2373     Builder.CreateStore(V, Ptr);
2374     V = Ptr.getPointer();
2375   }
2376   return Builder.CreatePtrToInt(V, TargetTy);
2377 }
2378 
2379 /// \brief Emit a representation of a SourceLocation for passing to a handler
2380 /// in a sanitizer runtime library. The format for this data is:
2381 /// \code
2382 ///   struct SourceLocation {
2383 ///     const char *Filename;
2384 ///     int32_t Line, Column;
2385 ///   };
2386 /// \endcode
2387 /// For an invalid SourceLocation, the Filename pointer is null.
EmitCheckSourceLocation(SourceLocation Loc)2388 llvm::Constant *CodeGenFunction::EmitCheckSourceLocation(SourceLocation Loc) {
2389   llvm::Constant *Filename;
2390   int Line, Column;
2391 
2392   PresumedLoc PLoc = getContext().getSourceManager().getPresumedLoc(Loc);
2393   if (PLoc.isValid()) {
2394     StringRef FilenameString = PLoc.getFilename();
2395 
2396     int PathComponentsToStrip =
2397         CGM.getCodeGenOpts().EmitCheckPathComponentsToStrip;
2398     if (PathComponentsToStrip < 0) {
2399       assert(PathComponentsToStrip != INT_MIN);
2400       int PathComponentsToKeep = -PathComponentsToStrip;
2401       auto I = llvm::sys::path::rbegin(FilenameString);
2402       auto E = llvm::sys::path::rend(FilenameString);
2403       while (I != E && --PathComponentsToKeep)
2404         ++I;
2405 
2406       FilenameString = FilenameString.substr(I - E);
2407     } else if (PathComponentsToStrip > 0) {
2408       auto I = llvm::sys::path::begin(FilenameString);
2409       auto E = llvm::sys::path::end(FilenameString);
2410       while (I != E && PathComponentsToStrip--)
2411         ++I;
2412 
2413       if (I != E)
2414         FilenameString =
2415             FilenameString.substr(I - llvm::sys::path::begin(FilenameString));
2416       else
2417         FilenameString = llvm::sys::path::filename(FilenameString);
2418     }
2419 
2420     auto FilenameGV = CGM.GetAddrOfConstantCString(FilenameString, ".src");
2421     CGM.getSanitizerMetadata()->disableSanitizerForGlobal(
2422                           cast<llvm::GlobalVariable>(FilenameGV.getPointer()));
2423     Filename = FilenameGV.getPointer();
2424     Line = PLoc.getLine();
2425     Column = PLoc.getColumn();
2426   } else {
2427     Filename = llvm::Constant::getNullValue(Int8PtrTy);
2428     Line = Column = 0;
2429   }
2430 
2431   llvm::Constant *Data[] = {Filename, Builder.getInt32(Line),
2432                             Builder.getInt32(Column)};
2433 
2434   return llvm::ConstantStruct::getAnon(Data);
2435 }
2436 
2437 namespace {
2438 /// \brief Specify under what conditions this check can be recovered
2439 enum class CheckRecoverableKind {
2440   /// Always terminate program execution if this check fails.
2441   Unrecoverable,
2442   /// Check supports recovering, runtime has both fatal (noreturn) and
2443   /// non-fatal handlers for this check.
2444   Recoverable,
2445   /// Runtime conditionally aborts, always need to support recovery.
2446   AlwaysRecoverable
2447 };
2448 }
2449 
getRecoverableKind(SanitizerMask Kind)2450 static CheckRecoverableKind getRecoverableKind(SanitizerMask Kind) {
2451   assert(llvm::countPopulation(Kind) == 1);
2452   switch (Kind) {
2453   case SanitizerKind::Vptr:
2454     return CheckRecoverableKind::AlwaysRecoverable;
2455   case SanitizerKind::Return:
2456   case SanitizerKind::Unreachable:
2457     return CheckRecoverableKind::Unrecoverable;
2458   default:
2459     return CheckRecoverableKind::Recoverable;
2460   }
2461 }
2462 
emitCheckHandlerCall(CodeGenFunction & CGF,llvm::FunctionType * FnType,ArrayRef<llvm::Value * > FnArgs,StringRef CheckName,CheckRecoverableKind RecoverKind,bool IsFatal,llvm::BasicBlock * ContBB)2463 static void emitCheckHandlerCall(CodeGenFunction &CGF,
2464                                  llvm::FunctionType *FnType,
2465                                  ArrayRef<llvm::Value *> FnArgs,
2466                                  StringRef CheckName,
2467                                  CheckRecoverableKind RecoverKind, bool IsFatal,
2468                                  llvm::BasicBlock *ContBB) {
2469   assert(IsFatal || RecoverKind != CheckRecoverableKind::Unrecoverable);
2470   bool NeedsAbortSuffix =
2471       IsFatal && RecoverKind != CheckRecoverableKind::Unrecoverable;
2472   std::string FnName = ("__ubsan_handle_" + CheckName +
2473                         (NeedsAbortSuffix ? "_abort" : "")).str();
2474   bool MayReturn =
2475       !IsFatal || RecoverKind == CheckRecoverableKind::AlwaysRecoverable;
2476 
2477   llvm::AttrBuilder B;
2478   if (!MayReturn) {
2479     B.addAttribute(llvm::Attribute::NoReturn)
2480         .addAttribute(llvm::Attribute::NoUnwind);
2481   }
2482   B.addAttribute(llvm::Attribute::UWTable);
2483 
2484   llvm::Value *Fn = CGF.CGM.CreateRuntimeFunction(
2485       FnType, FnName,
2486       llvm::AttributeSet::get(CGF.getLLVMContext(),
2487                               llvm::AttributeSet::FunctionIndex, B));
2488   llvm::CallInst *HandlerCall = CGF.EmitNounwindRuntimeCall(Fn, FnArgs);
2489   if (!MayReturn) {
2490     HandlerCall->setDoesNotReturn();
2491     CGF.Builder.CreateUnreachable();
2492   } else {
2493     CGF.Builder.CreateBr(ContBB);
2494   }
2495 }
2496 
EmitCheck(ArrayRef<std::pair<llvm::Value *,SanitizerMask>> Checked,StringRef CheckName,ArrayRef<llvm::Constant * > StaticArgs,ArrayRef<llvm::Value * > DynamicArgs)2497 void CodeGenFunction::EmitCheck(
2498     ArrayRef<std::pair<llvm::Value *, SanitizerMask>> Checked,
2499     StringRef CheckName, ArrayRef<llvm::Constant *> StaticArgs,
2500     ArrayRef<llvm::Value *> DynamicArgs) {
2501   assert(IsSanitizerScope);
2502   assert(Checked.size() > 0);
2503 
2504   llvm::Value *FatalCond = nullptr;
2505   llvm::Value *RecoverableCond = nullptr;
2506   llvm::Value *TrapCond = nullptr;
2507   for (int i = 0, n = Checked.size(); i < n; ++i) {
2508     llvm::Value *Check = Checked[i].first;
2509     // -fsanitize-trap= overrides -fsanitize-recover=.
2510     llvm::Value *&Cond =
2511         CGM.getCodeGenOpts().SanitizeTrap.has(Checked[i].second)
2512             ? TrapCond
2513             : CGM.getCodeGenOpts().SanitizeRecover.has(Checked[i].second)
2514                   ? RecoverableCond
2515                   : FatalCond;
2516     Cond = Cond ? Builder.CreateAnd(Cond, Check) : Check;
2517   }
2518 
2519   if (TrapCond)
2520     EmitTrapCheck(TrapCond);
2521   if (!FatalCond && !RecoverableCond)
2522     return;
2523 
2524   llvm::Value *JointCond;
2525   if (FatalCond && RecoverableCond)
2526     JointCond = Builder.CreateAnd(FatalCond, RecoverableCond);
2527   else
2528     JointCond = FatalCond ? FatalCond : RecoverableCond;
2529   assert(JointCond);
2530 
2531   CheckRecoverableKind RecoverKind = getRecoverableKind(Checked[0].second);
2532   assert(SanOpts.has(Checked[0].second));
2533 #ifndef NDEBUG
2534   for (int i = 1, n = Checked.size(); i < n; ++i) {
2535     assert(RecoverKind == getRecoverableKind(Checked[i].second) &&
2536            "All recoverable kinds in a single check must be same!");
2537     assert(SanOpts.has(Checked[i].second));
2538   }
2539 #endif
2540 
2541   llvm::BasicBlock *Cont = createBasicBlock("cont");
2542   llvm::BasicBlock *Handlers = createBasicBlock("handler." + CheckName);
2543   llvm::Instruction *Branch = Builder.CreateCondBr(JointCond, Cont, Handlers);
2544   // Give hint that we very much don't expect to execute the handler
2545   // Value chosen to match UR_NONTAKEN_WEIGHT, see BranchProbabilityInfo.cpp
2546   llvm::MDBuilder MDHelper(getLLVMContext());
2547   llvm::MDNode *Node = MDHelper.createBranchWeights((1U << 20) - 1, 1);
2548   Branch->setMetadata(llvm::LLVMContext::MD_prof, Node);
2549   EmitBlock(Handlers);
2550 
2551   // Handler functions take an i8* pointing to the (handler-specific) static
2552   // information block, followed by a sequence of intptr_t arguments
2553   // representing operand values.
2554   SmallVector<llvm::Value *, 4> Args;
2555   SmallVector<llvm::Type *, 4> ArgTypes;
2556   Args.reserve(DynamicArgs.size() + 1);
2557   ArgTypes.reserve(DynamicArgs.size() + 1);
2558 
2559   // Emit handler arguments and create handler function type.
2560   if (!StaticArgs.empty()) {
2561     llvm::Constant *Info = llvm::ConstantStruct::getAnon(StaticArgs);
2562     auto *InfoPtr =
2563         new llvm::GlobalVariable(CGM.getModule(), Info->getType(), false,
2564                                  llvm::GlobalVariable::PrivateLinkage, Info);
2565     InfoPtr->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
2566     CGM.getSanitizerMetadata()->disableSanitizerForGlobal(InfoPtr);
2567     Args.push_back(Builder.CreateBitCast(InfoPtr, Int8PtrTy));
2568     ArgTypes.push_back(Int8PtrTy);
2569   }
2570 
2571   for (size_t i = 0, n = DynamicArgs.size(); i != n; ++i) {
2572     Args.push_back(EmitCheckValue(DynamicArgs[i]));
2573     ArgTypes.push_back(IntPtrTy);
2574   }
2575 
2576   llvm::FunctionType *FnType =
2577     llvm::FunctionType::get(CGM.VoidTy, ArgTypes, false);
2578 
2579   if (!FatalCond || !RecoverableCond) {
2580     // Simple case: we need to generate a single handler call, either
2581     // fatal, or non-fatal.
2582     emitCheckHandlerCall(*this, FnType, Args, CheckName, RecoverKind,
2583                          (FatalCond != nullptr), Cont);
2584   } else {
2585     // Emit two handler calls: first one for set of unrecoverable checks,
2586     // another one for recoverable.
2587     llvm::BasicBlock *NonFatalHandlerBB =
2588         createBasicBlock("non_fatal." + CheckName);
2589     llvm::BasicBlock *FatalHandlerBB = createBasicBlock("fatal." + CheckName);
2590     Builder.CreateCondBr(FatalCond, NonFatalHandlerBB, FatalHandlerBB);
2591     EmitBlock(FatalHandlerBB);
2592     emitCheckHandlerCall(*this, FnType, Args, CheckName, RecoverKind, true,
2593                          NonFatalHandlerBB);
2594     EmitBlock(NonFatalHandlerBB);
2595     emitCheckHandlerCall(*this, FnType, Args, CheckName, RecoverKind, false,
2596                          Cont);
2597   }
2598 
2599   EmitBlock(Cont);
2600 }
2601 
EmitCfiSlowPathCheck(SanitizerMask Kind,llvm::Value * Cond,llvm::ConstantInt * TypeId,llvm::Value * Ptr,ArrayRef<llvm::Constant * > StaticArgs)2602 void CodeGenFunction::EmitCfiSlowPathCheck(
2603     SanitizerMask Kind, llvm::Value *Cond, llvm::ConstantInt *TypeId,
2604     llvm::Value *Ptr, ArrayRef<llvm::Constant *> StaticArgs) {
2605   llvm::BasicBlock *Cont = createBasicBlock("cfi.cont");
2606 
2607   llvm::BasicBlock *CheckBB = createBasicBlock("cfi.slowpath");
2608   llvm::BranchInst *BI = Builder.CreateCondBr(Cond, Cont, CheckBB);
2609 
2610   llvm::MDBuilder MDHelper(getLLVMContext());
2611   llvm::MDNode *Node = MDHelper.createBranchWeights((1U << 20) - 1, 1);
2612   BI->setMetadata(llvm::LLVMContext::MD_prof, Node);
2613 
2614   EmitBlock(CheckBB);
2615 
2616   bool WithDiag = !CGM.getCodeGenOpts().SanitizeTrap.has(Kind);
2617 
2618   llvm::CallInst *CheckCall;
2619   if (WithDiag) {
2620     llvm::Constant *Info = llvm::ConstantStruct::getAnon(StaticArgs);
2621     auto *InfoPtr =
2622         new llvm::GlobalVariable(CGM.getModule(), Info->getType(), false,
2623                                  llvm::GlobalVariable::PrivateLinkage, Info);
2624     InfoPtr->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
2625     CGM.getSanitizerMetadata()->disableSanitizerForGlobal(InfoPtr);
2626 
2627     llvm::Constant *SlowPathDiagFn = CGM.getModule().getOrInsertFunction(
2628         "__cfi_slowpath_diag",
2629         llvm::FunctionType::get(VoidTy, {Int64Ty, Int8PtrTy, Int8PtrTy},
2630                                 false));
2631     CheckCall = Builder.CreateCall(
2632         SlowPathDiagFn,
2633         {TypeId, Ptr, Builder.CreateBitCast(InfoPtr, Int8PtrTy)});
2634   } else {
2635     llvm::Constant *SlowPathFn = CGM.getModule().getOrInsertFunction(
2636         "__cfi_slowpath",
2637         llvm::FunctionType::get(VoidTy, {Int64Ty, Int8PtrTy}, false));
2638     CheckCall = Builder.CreateCall(SlowPathFn, {TypeId, Ptr});
2639   }
2640 
2641   CheckCall->setDoesNotThrow();
2642 
2643   EmitBlock(Cont);
2644 }
2645 
2646 // This function is basically a switch over the CFI failure kind, which is
2647 // extracted from CFICheckFailData (1st function argument). Each case is either
2648 // llvm.trap or a call to one of the two runtime handlers, based on
2649 // -fsanitize-trap and -fsanitize-recover settings.  Default case (invalid
2650 // failure kind) traps, but this should really never happen.  CFICheckFailData
2651 // can be nullptr if the calling module has -fsanitize-trap behavior for this
2652 // check kind; in this case __cfi_check_fail traps as well.
EmitCfiCheckFail()2653 void CodeGenFunction::EmitCfiCheckFail() {
2654   SanitizerScope SanScope(this);
2655   FunctionArgList Args;
2656   ImplicitParamDecl ArgData(getContext(), nullptr, SourceLocation(), nullptr,
2657                             getContext().VoidPtrTy);
2658   ImplicitParamDecl ArgAddr(getContext(), nullptr, SourceLocation(), nullptr,
2659                             getContext().VoidPtrTy);
2660   Args.push_back(&ArgData);
2661   Args.push_back(&ArgAddr);
2662 
2663   const CGFunctionInfo &FI =
2664     CGM.getTypes().arrangeBuiltinFunctionDeclaration(getContext().VoidTy, Args);
2665 
2666   llvm::Function *F = llvm::Function::Create(
2667       llvm::FunctionType::get(VoidTy, {VoidPtrTy, VoidPtrTy}, false),
2668       llvm::GlobalValue::WeakODRLinkage, "__cfi_check_fail", &CGM.getModule());
2669   F->setVisibility(llvm::GlobalValue::HiddenVisibility);
2670 
2671   StartFunction(GlobalDecl(), CGM.getContext().VoidTy, F, FI, Args,
2672                 SourceLocation());
2673 
2674   llvm::Value *Data =
2675       EmitLoadOfScalar(GetAddrOfLocalVar(&ArgData), /*Volatile=*/false,
2676                        CGM.getContext().VoidPtrTy, ArgData.getLocation());
2677   llvm::Value *Addr =
2678       EmitLoadOfScalar(GetAddrOfLocalVar(&ArgAddr), /*Volatile=*/false,
2679                        CGM.getContext().VoidPtrTy, ArgAddr.getLocation());
2680 
2681   // Data == nullptr means the calling module has trap behaviour for this check.
2682   llvm::Value *DataIsNotNullPtr =
2683       Builder.CreateICmpNE(Data, llvm::ConstantPointerNull::get(Int8PtrTy));
2684   EmitTrapCheck(DataIsNotNullPtr);
2685 
2686   llvm::StructType *SourceLocationTy =
2687       llvm::StructType::get(VoidPtrTy, Int32Ty, Int32Ty, nullptr);
2688   llvm::StructType *CfiCheckFailDataTy =
2689       llvm::StructType::get(Int8Ty, SourceLocationTy, VoidPtrTy, nullptr);
2690 
2691   llvm::Value *V = Builder.CreateConstGEP2_32(
2692       CfiCheckFailDataTy,
2693       Builder.CreatePointerCast(Data, CfiCheckFailDataTy->getPointerTo(0)), 0,
2694       0);
2695   Address CheckKindAddr(V, getIntAlign());
2696   llvm::Value *CheckKind = Builder.CreateLoad(CheckKindAddr);
2697 
2698   llvm::Value *AllVtables = llvm::MetadataAsValue::get(
2699       CGM.getLLVMContext(),
2700       llvm::MDString::get(CGM.getLLVMContext(), "all-vtables"));
2701   llvm::Value *ValidVtable = Builder.CreateZExt(
2702       Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::type_test),
2703                          {Addr, AllVtables}),
2704       IntPtrTy);
2705 
2706   const std::pair<int, SanitizerMask> CheckKinds[] = {
2707       {CFITCK_VCall, SanitizerKind::CFIVCall},
2708       {CFITCK_NVCall, SanitizerKind::CFINVCall},
2709       {CFITCK_DerivedCast, SanitizerKind::CFIDerivedCast},
2710       {CFITCK_UnrelatedCast, SanitizerKind::CFIUnrelatedCast},
2711       {CFITCK_ICall, SanitizerKind::CFIICall}};
2712 
2713   SmallVector<std::pair<llvm::Value *, SanitizerMask>, 5> Checks;
2714   for (auto CheckKindMaskPair : CheckKinds) {
2715     int Kind = CheckKindMaskPair.first;
2716     SanitizerMask Mask = CheckKindMaskPair.second;
2717     llvm::Value *Cond =
2718         Builder.CreateICmpNE(CheckKind, llvm::ConstantInt::get(Int8Ty, Kind));
2719     if (CGM.getLangOpts().Sanitize.has(Mask))
2720       EmitCheck(std::make_pair(Cond, Mask), "cfi_check_fail", {},
2721                 {Data, Addr, ValidVtable});
2722     else
2723       EmitTrapCheck(Cond);
2724   }
2725 
2726   FinishFunction();
2727   // The only reference to this function will be created during LTO link.
2728   // Make sure it survives until then.
2729   CGM.addUsedGlobal(F);
2730 }
2731 
EmitTrapCheck(llvm::Value * Checked)2732 void CodeGenFunction::EmitTrapCheck(llvm::Value *Checked) {
2733   llvm::BasicBlock *Cont = createBasicBlock("cont");
2734 
2735   // If we're optimizing, collapse all calls to trap down to just one per
2736   // function to save on code size.
2737   if (!CGM.getCodeGenOpts().OptimizationLevel || !TrapBB) {
2738     TrapBB = createBasicBlock("trap");
2739     Builder.CreateCondBr(Checked, Cont, TrapBB);
2740     EmitBlock(TrapBB);
2741     llvm::CallInst *TrapCall = EmitTrapCall(llvm::Intrinsic::trap);
2742     TrapCall->setDoesNotReturn();
2743     TrapCall->setDoesNotThrow();
2744     Builder.CreateUnreachable();
2745   } else {
2746     Builder.CreateCondBr(Checked, Cont, TrapBB);
2747   }
2748 
2749   EmitBlock(Cont);
2750 }
2751 
EmitTrapCall(llvm::Intrinsic::ID IntrID)2752 llvm::CallInst *CodeGenFunction::EmitTrapCall(llvm::Intrinsic::ID IntrID) {
2753   llvm::CallInst *TrapCall = Builder.CreateCall(CGM.getIntrinsic(IntrID));
2754 
2755   if (!CGM.getCodeGenOpts().TrapFuncName.empty())
2756     TrapCall->addAttribute(llvm::AttributeSet::FunctionIndex,
2757                            "trap-func-name",
2758                            CGM.getCodeGenOpts().TrapFuncName);
2759 
2760   return TrapCall;
2761 }
2762 
EmitArrayToPointerDecay(const Expr * E,AlignmentSource * AlignSource)2763 Address CodeGenFunction::EmitArrayToPointerDecay(const Expr *E,
2764                                                  AlignmentSource *AlignSource) {
2765   assert(E->getType()->isArrayType() &&
2766          "Array to pointer decay must have array source type!");
2767 
2768   // Expressions of array type can't be bitfields or vector elements.
2769   LValue LV = EmitLValue(E);
2770   Address Addr = LV.getAddress();
2771   if (AlignSource) *AlignSource = LV.getAlignmentSource();
2772 
2773   // If the array type was an incomplete type, we need to make sure
2774   // the decay ends up being the right type.
2775   llvm::Type *NewTy = ConvertType(E->getType());
2776   Addr = Builder.CreateElementBitCast(Addr, NewTy);
2777 
2778   // Note that VLA pointers are always decayed, so we don't need to do
2779   // anything here.
2780   if (!E->getType()->isVariableArrayType()) {
2781     assert(isa<llvm::ArrayType>(Addr.getElementType()) &&
2782            "Expected pointer to array");
2783     Addr = Builder.CreateStructGEP(Addr, 0, CharUnits::Zero(), "arraydecay");
2784   }
2785 
2786   QualType EltType = E->getType()->castAsArrayTypeUnsafe()->getElementType();
2787   return Builder.CreateElementBitCast(Addr, ConvertTypeForMem(EltType));
2788 }
2789 
2790 /// isSimpleArrayDecayOperand - If the specified expr is a simple decay from an
2791 /// array to pointer, return the array subexpression.
isSimpleArrayDecayOperand(const Expr * E)2792 static const Expr *isSimpleArrayDecayOperand(const Expr *E) {
2793   // If this isn't just an array->pointer decay, bail out.
2794   const auto *CE = dyn_cast<CastExpr>(E);
2795   if (!CE || CE->getCastKind() != CK_ArrayToPointerDecay)
2796     return nullptr;
2797 
2798   // If this is a decay from variable width array, bail out.
2799   const Expr *SubExpr = CE->getSubExpr();
2800   if (SubExpr->getType()->isVariableArrayType())
2801     return nullptr;
2802 
2803   return SubExpr;
2804 }
2805 
emitArraySubscriptGEP(CodeGenFunction & CGF,llvm::Value * ptr,ArrayRef<llvm::Value * > indices,bool inbounds,const llvm::Twine & name="arrayidx")2806 static llvm::Value *emitArraySubscriptGEP(CodeGenFunction &CGF,
2807                                           llvm::Value *ptr,
2808                                           ArrayRef<llvm::Value*> indices,
2809                                           bool inbounds,
2810                                     const llvm::Twine &name = "arrayidx") {
2811   if (inbounds) {
2812     return CGF.Builder.CreateInBoundsGEP(ptr, indices, name);
2813   } else {
2814     return CGF.Builder.CreateGEP(ptr, indices, name);
2815   }
2816 }
2817 
getArrayElementAlign(CharUnits arrayAlign,llvm::Value * idx,CharUnits eltSize)2818 static CharUnits getArrayElementAlign(CharUnits arrayAlign,
2819                                       llvm::Value *idx,
2820                                       CharUnits eltSize) {
2821   // If we have a constant index, we can use the exact offset of the
2822   // element we're accessing.
2823   if (auto constantIdx = dyn_cast<llvm::ConstantInt>(idx)) {
2824     CharUnits offset = constantIdx->getZExtValue() * eltSize;
2825     return arrayAlign.alignmentAtOffset(offset);
2826 
2827   // Otherwise, use the worst-case alignment for any element.
2828   } else {
2829     return arrayAlign.alignmentOfArrayElement(eltSize);
2830   }
2831 }
2832 
getFixedSizeElementType(const ASTContext & ctx,const VariableArrayType * vla)2833 static QualType getFixedSizeElementType(const ASTContext &ctx,
2834                                         const VariableArrayType *vla) {
2835   QualType eltType;
2836   do {
2837     eltType = vla->getElementType();
2838   } while ((vla = ctx.getAsVariableArrayType(eltType)));
2839   return eltType;
2840 }
2841 
emitArraySubscriptGEP(CodeGenFunction & CGF,Address addr,ArrayRef<llvm::Value * > indices,QualType eltType,bool inbounds,const llvm::Twine & name="arrayidx")2842 static Address emitArraySubscriptGEP(CodeGenFunction &CGF, Address addr,
2843                                      ArrayRef<llvm::Value*> indices,
2844                                      QualType eltType, bool inbounds,
2845                                      const llvm::Twine &name = "arrayidx") {
2846   // All the indices except that last must be zero.
2847 #ifndef NDEBUG
2848   for (auto idx : indices.drop_back())
2849     assert(isa<llvm::ConstantInt>(idx) &&
2850            cast<llvm::ConstantInt>(idx)->isZero());
2851 #endif
2852 
2853   // Determine the element size of the statically-sized base.  This is
2854   // the thing that the indices are expressed in terms of.
2855   if (auto vla = CGF.getContext().getAsVariableArrayType(eltType)) {
2856     eltType = getFixedSizeElementType(CGF.getContext(), vla);
2857   }
2858 
2859   // We can use that to compute the best alignment of the element.
2860   CharUnits eltSize = CGF.getContext().getTypeSizeInChars(eltType);
2861   CharUnits eltAlign =
2862     getArrayElementAlign(addr.getAlignment(), indices.back(), eltSize);
2863 
2864   llvm::Value *eltPtr =
2865     emitArraySubscriptGEP(CGF, addr.getPointer(), indices, inbounds, name);
2866   return Address(eltPtr, eltAlign);
2867 }
2868 
EmitArraySubscriptExpr(const ArraySubscriptExpr * E,bool Accessed)2869 LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E,
2870                                                bool Accessed) {
2871   // The index must always be an integer, which is not an aggregate.  Emit it.
2872   llvm::Value *Idx = EmitScalarExpr(E->getIdx());
2873   QualType IdxTy  = E->getIdx()->getType();
2874   bool IdxSigned = IdxTy->isSignedIntegerOrEnumerationType();
2875 
2876   if (SanOpts.has(SanitizerKind::ArrayBounds))
2877     EmitBoundsCheck(E, E->getBase(), Idx, IdxTy, Accessed);
2878 
2879   // If the base is a vector type, then we are forming a vector element lvalue
2880   // with this subscript.
2881   if (E->getBase()->getType()->isVectorType() &&
2882       !isa<ExtVectorElementExpr>(E->getBase())) {
2883     // Emit the vector as an lvalue to get its address.
2884     LValue LHS = EmitLValue(E->getBase());
2885     assert(LHS.isSimple() && "Can only subscript lvalue vectors here!");
2886     return LValue::MakeVectorElt(LHS.getAddress(), Idx,
2887                                  E->getBase()->getType(),
2888                                  LHS.getAlignmentSource());
2889   }
2890 
2891   // All the other cases basically behave like simple offsetting.
2892 
2893   // Extend or truncate the index type to 32 or 64-bits.
2894   if (Idx->getType() != IntPtrTy)
2895     Idx = Builder.CreateIntCast(Idx, IntPtrTy, IdxSigned, "idxprom");
2896 
2897   // Handle the extvector case we ignored above.
2898   if (isa<ExtVectorElementExpr>(E->getBase())) {
2899     LValue LV = EmitLValue(E->getBase());
2900     Address Addr = EmitExtVectorElementLValue(LV);
2901 
2902     QualType EltType = LV.getType()->castAs<VectorType>()->getElementType();
2903     Addr = emitArraySubscriptGEP(*this, Addr, Idx, EltType, /*inbounds*/ true);
2904     return MakeAddrLValue(Addr, EltType, LV.getAlignmentSource());
2905   }
2906 
2907   AlignmentSource AlignSource;
2908   Address Addr = Address::invalid();
2909   if (const VariableArrayType *vla =
2910            getContext().getAsVariableArrayType(E->getType())) {
2911     // The base must be a pointer, which is not an aggregate.  Emit
2912     // it.  It needs to be emitted first in case it's what captures
2913     // the VLA bounds.
2914     Addr = EmitPointerWithAlignment(E->getBase(), &AlignSource);
2915 
2916     // The element count here is the total number of non-VLA elements.
2917     llvm::Value *numElements = getVLASize(vla).first;
2918 
2919     // Effectively, the multiply by the VLA size is part of the GEP.
2920     // GEP indexes are signed, and scaling an index isn't permitted to
2921     // signed-overflow, so we use the same semantics for our explicit
2922     // multiply.  We suppress this if overflow is not undefined behavior.
2923     if (getLangOpts().isSignedOverflowDefined()) {
2924       Idx = Builder.CreateMul(Idx, numElements);
2925     } else {
2926       Idx = Builder.CreateNSWMul(Idx, numElements);
2927     }
2928 
2929     Addr = emitArraySubscriptGEP(*this, Addr, Idx, vla->getElementType(),
2930                                  !getLangOpts().isSignedOverflowDefined());
2931 
2932   } else if (const ObjCObjectType *OIT = E->getType()->getAs<ObjCObjectType>()){
2933     // Indexing over an interface, as in "NSString *P; P[4];"
2934     CharUnits InterfaceSize = getContext().getTypeSizeInChars(OIT);
2935     llvm::Value *InterfaceSizeVal =
2936       llvm::ConstantInt::get(Idx->getType(), InterfaceSize.getQuantity());;
2937 
2938     llvm::Value *ScaledIdx = Builder.CreateMul(Idx, InterfaceSizeVal);
2939 
2940     // Emit the base pointer.
2941     Addr = EmitPointerWithAlignment(E->getBase(), &AlignSource);
2942 
2943     // We don't necessarily build correct LLVM struct types for ObjC
2944     // interfaces, so we can't rely on GEP to do this scaling
2945     // correctly, so we need to cast to i8*.  FIXME: is this actually
2946     // true?  A lot of other things in the fragile ABI would break...
2947     llvm::Type *OrigBaseTy = Addr.getType();
2948     Addr = Builder.CreateElementBitCast(Addr, Int8Ty);
2949 
2950     // Do the GEP.
2951     CharUnits EltAlign =
2952       getArrayElementAlign(Addr.getAlignment(), Idx, InterfaceSize);
2953     llvm::Value *EltPtr =
2954       emitArraySubscriptGEP(*this, Addr.getPointer(), ScaledIdx, false);
2955     Addr = Address(EltPtr, EltAlign);
2956 
2957     // Cast back.
2958     Addr = Builder.CreateBitCast(Addr, OrigBaseTy);
2959   } else if (const Expr *Array = isSimpleArrayDecayOperand(E->getBase())) {
2960     // If this is A[i] where A is an array, the frontend will have decayed the
2961     // base to be a ArrayToPointerDecay implicit cast.  While correct, it is
2962     // inefficient at -O0 to emit a "gep A, 0, 0" when codegen'ing it, then a
2963     // "gep x, i" here.  Emit one "gep A, 0, i".
2964     assert(Array->getType()->isArrayType() &&
2965            "Array to pointer decay must have array source type!");
2966     LValue ArrayLV;
2967     // For simple multidimensional array indexing, set the 'accessed' flag for
2968     // better bounds-checking of the base expression.
2969     if (const auto *ASE = dyn_cast<ArraySubscriptExpr>(Array))
2970       ArrayLV = EmitArraySubscriptExpr(ASE, /*Accessed*/ true);
2971     else
2972       ArrayLV = EmitLValue(Array);
2973 
2974     // Propagate the alignment from the array itself to the result.
2975     Addr = emitArraySubscriptGEP(*this, ArrayLV.getAddress(),
2976                                  {CGM.getSize(CharUnits::Zero()), Idx},
2977                                  E->getType(),
2978                                  !getLangOpts().isSignedOverflowDefined());
2979     AlignSource = ArrayLV.getAlignmentSource();
2980   } else {
2981     // The base must be a pointer; emit it with an estimate of its alignment.
2982     Addr = EmitPointerWithAlignment(E->getBase(), &AlignSource);
2983     Addr = emitArraySubscriptGEP(*this, Addr, Idx, E->getType(),
2984                                  !getLangOpts().isSignedOverflowDefined());
2985   }
2986 
2987   LValue LV = MakeAddrLValue(Addr, E->getType(), AlignSource);
2988 
2989   // TODO: Preserve/extend path TBAA metadata?
2990 
2991   if (getLangOpts().ObjC1 &&
2992       getLangOpts().getGC() != LangOptions::NonGC) {
2993     LV.setNonGC(!E->isOBJCGCCandidate(getContext()));
2994     setObjCGCLValueClass(getContext(), E, LV);
2995   }
2996   return LV;
2997 }
2998 
emitOMPArraySectionBase(CodeGenFunction & CGF,const Expr * Base,AlignmentSource & AlignSource,QualType BaseTy,QualType ElTy,bool IsLowerBound)2999 static Address emitOMPArraySectionBase(CodeGenFunction &CGF, const Expr *Base,
3000                                        AlignmentSource &AlignSource,
3001                                        QualType BaseTy, QualType ElTy,
3002                                        bool IsLowerBound) {
3003   LValue BaseLVal;
3004   if (auto *ASE = dyn_cast<OMPArraySectionExpr>(Base->IgnoreParenImpCasts())) {
3005     BaseLVal = CGF.EmitOMPArraySectionExpr(ASE, IsLowerBound);
3006     if (BaseTy->isArrayType()) {
3007       Address Addr = BaseLVal.getAddress();
3008       AlignSource = BaseLVal.getAlignmentSource();
3009 
3010       // If the array type was an incomplete type, we need to make sure
3011       // the decay ends up being the right type.
3012       llvm::Type *NewTy = CGF.ConvertType(BaseTy);
3013       Addr = CGF.Builder.CreateElementBitCast(Addr, NewTy);
3014 
3015       // Note that VLA pointers are always decayed, so we don't need to do
3016       // anything here.
3017       if (!BaseTy->isVariableArrayType()) {
3018         assert(isa<llvm::ArrayType>(Addr.getElementType()) &&
3019                "Expected pointer to array");
3020         Addr = CGF.Builder.CreateStructGEP(Addr, 0, CharUnits::Zero(),
3021                                            "arraydecay");
3022       }
3023 
3024       return CGF.Builder.CreateElementBitCast(Addr,
3025                                               CGF.ConvertTypeForMem(ElTy));
3026     }
3027     CharUnits Align = CGF.getNaturalTypeAlignment(ElTy, &AlignSource);
3028     return Address(CGF.Builder.CreateLoad(BaseLVal.getAddress()), Align);
3029   }
3030   return CGF.EmitPointerWithAlignment(Base, &AlignSource);
3031 }
3032 
EmitOMPArraySectionExpr(const OMPArraySectionExpr * E,bool IsLowerBound)3033 LValue CodeGenFunction::EmitOMPArraySectionExpr(const OMPArraySectionExpr *E,
3034                                                 bool IsLowerBound) {
3035   QualType BaseTy;
3036   if (auto *ASE =
3037           dyn_cast<OMPArraySectionExpr>(E->getBase()->IgnoreParenImpCasts()))
3038     BaseTy = OMPArraySectionExpr::getBaseOriginalType(ASE);
3039   else
3040     BaseTy = E->getBase()->getType();
3041   QualType ResultExprTy;
3042   if (auto *AT = getContext().getAsArrayType(BaseTy))
3043     ResultExprTy = AT->getElementType();
3044   else
3045     ResultExprTy = BaseTy->getPointeeType();
3046   llvm::Value *Idx = nullptr;
3047   if (IsLowerBound || E->getColonLoc().isInvalid()) {
3048     // Requesting lower bound or upper bound, but without provided length and
3049     // without ':' symbol for the default length -> length = 1.
3050     // Idx = LowerBound ?: 0;
3051     if (auto *LowerBound = E->getLowerBound()) {
3052       Idx = Builder.CreateIntCast(
3053           EmitScalarExpr(LowerBound), IntPtrTy,
3054           LowerBound->getType()->hasSignedIntegerRepresentation());
3055     } else
3056       Idx = llvm::ConstantInt::getNullValue(IntPtrTy);
3057   } else {
3058     // Try to emit length or lower bound as constant. If this is possible, 1
3059     // is subtracted from constant length or lower bound. Otherwise, emit LLVM
3060     // IR (LB + Len) - 1.
3061     auto &C = CGM.getContext();
3062     auto *Length = E->getLength();
3063     llvm::APSInt ConstLength;
3064     if (Length) {
3065       // Idx = LowerBound + Length - 1;
3066       if (Length->isIntegerConstantExpr(ConstLength, C)) {
3067         ConstLength = ConstLength.zextOrTrunc(PointerWidthInBits);
3068         Length = nullptr;
3069       }
3070       auto *LowerBound = E->getLowerBound();
3071       llvm::APSInt ConstLowerBound(PointerWidthInBits, /*isUnsigned=*/false);
3072       if (LowerBound && LowerBound->isIntegerConstantExpr(ConstLowerBound, C)) {
3073         ConstLowerBound = ConstLowerBound.zextOrTrunc(PointerWidthInBits);
3074         LowerBound = nullptr;
3075       }
3076       if (!Length)
3077         --ConstLength;
3078       else if (!LowerBound)
3079         --ConstLowerBound;
3080 
3081       if (Length || LowerBound) {
3082         auto *LowerBoundVal =
3083             LowerBound
3084                 ? Builder.CreateIntCast(
3085                       EmitScalarExpr(LowerBound), IntPtrTy,
3086                       LowerBound->getType()->hasSignedIntegerRepresentation())
3087                 : llvm::ConstantInt::get(IntPtrTy, ConstLowerBound);
3088         auto *LengthVal =
3089             Length
3090                 ? Builder.CreateIntCast(
3091                       EmitScalarExpr(Length), IntPtrTy,
3092                       Length->getType()->hasSignedIntegerRepresentation())
3093                 : llvm::ConstantInt::get(IntPtrTy, ConstLength);
3094         Idx = Builder.CreateAdd(LowerBoundVal, LengthVal, "lb_add_len",
3095                                 /*HasNUW=*/false,
3096                                 !getLangOpts().isSignedOverflowDefined());
3097         if (Length && LowerBound) {
3098           Idx = Builder.CreateSub(
3099               Idx, llvm::ConstantInt::get(IntPtrTy, /*V=*/1), "idx_sub_1",
3100               /*HasNUW=*/false, !getLangOpts().isSignedOverflowDefined());
3101         }
3102       } else
3103         Idx = llvm::ConstantInt::get(IntPtrTy, ConstLength + ConstLowerBound);
3104     } else {
3105       // Idx = ArraySize - 1;
3106       QualType ArrayTy = BaseTy->isPointerType()
3107                              ? E->getBase()->IgnoreParenImpCasts()->getType()
3108                              : BaseTy;
3109       if (auto *VAT = C.getAsVariableArrayType(ArrayTy)) {
3110         Length = VAT->getSizeExpr();
3111         if (Length->isIntegerConstantExpr(ConstLength, C))
3112           Length = nullptr;
3113       } else {
3114         auto *CAT = C.getAsConstantArrayType(ArrayTy);
3115         ConstLength = CAT->getSize();
3116       }
3117       if (Length) {
3118         auto *LengthVal = Builder.CreateIntCast(
3119             EmitScalarExpr(Length), IntPtrTy,
3120             Length->getType()->hasSignedIntegerRepresentation());
3121         Idx = Builder.CreateSub(
3122             LengthVal, llvm::ConstantInt::get(IntPtrTy, /*V=*/1), "len_sub_1",
3123             /*HasNUW=*/false, !getLangOpts().isSignedOverflowDefined());
3124       } else {
3125         ConstLength = ConstLength.zextOrTrunc(PointerWidthInBits);
3126         --ConstLength;
3127         Idx = llvm::ConstantInt::get(IntPtrTy, ConstLength);
3128       }
3129     }
3130   }
3131   assert(Idx);
3132 
3133   Address EltPtr = Address::invalid();
3134   AlignmentSource AlignSource;
3135   if (auto *VLA = getContext().getAsVariableArrayType(ResultExprTy)) {
3136     // The base must be a pointer, which is not an aggregate.  Emit
3137     // it.  It needs to be emitted first in case it's what captures
3138     // the VLA bounds.
3139     Address Base =
3140         emitOMPArraySectionBase(*this, E->getBase(), AlignSource, BaseTy,
3141                                 VLA->getElementType(), IsLowerBound);
3142     // The element count here is the total number of non-VLA elements.
3143     llvm::Value *NumElements = getVLASize(VLA).first;
3144 
3145     // Effectively, the multiply by the VLA size is part of the GEP.
3146     // GEP indexes are signed, and scaling an index isn't permitted to
3147     // signed-overflow, so we use the same semantics for our explicit
3148     // multiply.  We suppress this if overflow is not undefined behavior.
3149     if (getLangOpts().isSignedOverflowDefined())
3150       Idx = Builder.CreateMul(Idx, NumElements);
3151     else
3152       Idx = Builder.CreateNSWMul(Idx, NumElements);
3153     EltPtr = emitArraySubscriptGEP(*this, Base, Idx, VLA->getElementType(),
3154                                    !getLangOpts().isSignedOverflowDefined());
3155   } else if (const Expr *Array = isSimpleArrayDecayOperand(E->getBase())) {
3156     // If this is A[i] where A is an array, the frontend will have decayed the
3157     // base to be a ArrayToPointerDecay implicit cast.  While correct, it is
3158     // inefficient at -O0 to emit a "gep A, 0, 0" when codegen'ing it, then a
3159     // "gep x, i" here.  Emit one "gep A, 0, i".
3160     assert(Array->getType()->isArrayType() &&
3161            "Array to pointer decay must have array source type!");
3162     LValue ArrayLV;
3163     // For simple multidimensional array indexing, set the 'accessed' flag for
3164     // better bounds-checking of the base expression.
3165     if (const auto *ASE = dyn_cast<ArraySubscriptExpr>(Array))
3166       ArrayLV = EmitArraySubscriptExpr(ASE, /*Accessed*/ true);
3167     else
3168       ArrayLV = EmitLValue(Array);
3169 
3170     // Propagate the alignment from the array itself to the result.
3171     EltPtr = emitArraySubscriptGEP(
3172         *this, ArrayLV.getAddress(), {CGM.getSize(CharUnits::Zero()), Idx},
3173         ResultExprTy, !getLangOpts().isSignedOverflowDefined());
3174     AlignSource = ArrayLV.getAlignmentSource();
3175   } else {
3176     Address Base = emitOMPArraySectionBase(*this, E->getBase(), AlignSource,
3177                                            BaseTy, ResultExprTy, IsLowerBound);
3178     EltPtr = emitArraySubscriptGEP(*this, Base, Idx, ResultExprTy,
3179                                    !getLangOpts().isSignedOverflowDefined());
3180   }
3181 
3182   return MakeAddrLValue(EltPtr, ResultExprTy, AlignSource);
3183 }
3184 
3185 LValue CodeGenFunction::
EmitExtVectorElementExpr(const ExtVectorElementExpr * E)3186 EmitExtVectorElementExpr(const ExtVectorElementExpr *E) {
3187   // Emit the base vector as an l-value.
3188   LValue Base;
3189 
3190   // ExtVectorElementExpr's base can either be a vector or pointer to vector.
3191   if (E->isArrow()) {
3192     // If it is a pointer to a vector, emit the address and form an lvalue with
3193     // it.
3194     AlignmentSource AlignSource;
3195     Address Ptr = EmitPointerWithAlignment(E->getBase(), &AlignSource);
3196     const PointerType *PT = E->getBase()->getType()->getAs<PointerType>();
3197     Base = MakeAddrLValue(Ptr, PT->getPointeeType(), AlignSource);
3198     Base.getQuals().removeObjCGCAttr();
3199   } else if (E->getBase()->isGLValue()) {
3200     // Otherwise, if the base is an lvalue ( as in the case of foo.x.x),
3201     // emit the base as an lvalue.
3202     assert(E->getBase()->getType()->isVectorType());
3203     Base = EmitLValue(E->getBase());
3204   } else {
3205     // Otherwise, the base is a normal rvalue (as in (V+V).x), emit it as such.
3206     assert(E->getBase()->getType()->isVectorType() &&
3207            "Result must be a vector");
3208     llvm::Value *Vec = EmitScalarExpr(E->getBase());
3209 
3210     // Store the vector to memory (because LValue wants an address).
3211     Address VecMem = CreateMemTemp(E->getBase()->getType());
3212     Builder.CreateStore(Vec, VecMem);
3213     Base = MakeAddrLValue(VecMem, E->getBase()->getType(),
3214                           AlignmentSource::Decl);
3215   }
3216 
3217   QualType type =
3218     E->getType().withCVRQualifiers(Base.getQuals().getCVRQualifiers());
3219 
3220   // Encode the element access list into a vector of unsigned indices.
3221   SmallVector<uint32_t, 4> Indices;
3222   E->getEncodedElementAccess(Indices);
3223 
3224   if (Base.isSimple()) {
3225     llvm::Constant *CV =
3226         llvm::ConstantDataVector::get(getLLVMContext(), Indices);
3227     return LValue::MakeExtVectorElt(Base.getAddress(), CV, type,
3228                                     Base.getAlignmentSource());
3229   }
3230   assert(Base.isExtVectorElt() && "Can only subscript lvalue vec elts here!");
3231 
3232   llvm::Constant *BaseElts = Base.getExtVectorElts();
3233   SmallVector<llvm::Constant *, 4> CElts;
3234 
3235   for (unsigned i = 0, e = Indices.size(); i != e; ++i)
3236     CElts.push_back(BaseElts->getAggregateElement(Indices[i]));
3237   llvm::Constant *CV = llvm::ConstantVector::get(CElts);
3238   return LValue::MakeExtVectorElt(Base.getExtVectorAddress(), CV, type,
3239                                   Base.getAlignmentSource());
3240 }
3241 
EmitMemberExpr(const MemberExpr * E)3242 LValue CodeGenFunction::EmitMemberExpr(const MemberExpr *E) {
3243   Expr *BaseExpr = E->getBase();
3244 
3245   // If this is s.x, emit s as an lvalue.  If it is s->x, emit s as a scalar.
3246   LValue BaseLV;
3247   if (E->isArrow()) {
3248     AlignmentSource AlignSource;
3249     Address Addr = EmitPointerWithAlignment(BaseExpr, &AlignSource);
3250     QualType PtrTy = BaseExpr->getType()->getPointeeType();
3251     EmitTypeCheck(TCK_MemberAccess, E->getExprLoc(), Addr.getPointer(), PtrTy);
3252     BaseLV = MakeAddrLValue(Addr, PtrTy, AlignSource);
3253   } else
3254     BaseLV = EmitCheckedLValue(BaseExpr, TCK_MemberAccess);
3255 
3256   NamedDecl *ND = E->getMemberDecl();
3257   if (auto *Field = dyn_cast<FieldDecl>(ND)) {
3258     LValue LV = EmitLValueForField(BaseLV, Field);
3259     setObjCGCLValueClass(getContext(), E, LV);
3260     return LV;
3261   }
3262 
3263   if (auto *VD = dyn_cast<VarDecl>(ND))
3264     return EmitGlobalVarDeclLValue(*this, E, VD);
3265 
3266   if (const auto *FD = dyn_cast<FunctionDecl>(ND))
3267     return EmitFunctionDeclLValue(*this, E, FD);
3268 
3269   llvm_unreachable("Unhandled member declaration!");
3270 }
3271 
3272 /// Given that we are currently emitting a lambda, emit an l-value for
3273 /// one of its members.
EmitLValueForLambdaField(const FieldDecl * Field)3274 LValue CodeGenFunction::EmitLValueForLambdaField(const FieldDecl *Field) {
3275   assert(cast<CXXMethodDecl>(CurCodeDecl)->getParent()->isLambda());
3276   assert(cast<CXXMethodDecl>(CurCodeDecl)->getParent() == Field->getParent());
3277   QualType LambdaTagType =
3278     getContext().getTagDeclType(Field->getParent());
3279   LValue LambdaLV = MakeNaturalAlignAddrLValue(CXXABIThisValue, LambdaTagType);
3280   return EmitLValueForField(LambdaLV, Field);
3281 }
3282 
3283 /// Drill down to the storage of a field without walking into
3284 /// reference types.
3285 ///
3286 /// The resulting address doesn't necessarily have the right type.
emitAddrOfFieldStorage(CodeGenFunction & CGF,Address base,const FieldDecl * field)3287 static Address emitAddrOfFieldStorage(CodeGenFunction &CGF, Address base,
3288                                       const FieldDecl *field) {
3289   const RecordDecl *rec = field->getParent();
3290 
3291   unsigned idx =
3292     CGF.CGM.getTypes().getCGRecordLayout(rec).getLLVMFieldNo(field);
3293 
3294   CharUnits offset;
3295   // Adjust the alignment down to the given offset.
3296   // As a special case, if the LLVM field index is 0, we know that this
3297   // is zero.
3298   assert((idx != 0 || CGF.getContext().getASTRecordLayout(rec)
3299                          .getFieldOffset(field->getFieldIndex()) == 0) &&
3300          "LLVM field at index zero had non-zero offset?");
3301   if (idx != 0) {
3302     auto &recLayout = CGF.getContext().getASTRecordLayout(rec);
3303     auto offsetInBits = recLayout.getFieldOffset(field->getFieldIndex());
3304     offset = CGF.getContext().toCharUnitsFromBits(offsetInBits);
3305   }
3306 
3307   return CGF.Builder.CreateStructGEP(base, idx, offset, field->getName());
3308 }
3309 
EmitLValueForField(LValue base,const FieldDecl * field)3310 LValue CodeGenFunction::EmitLValueForField(LValue base,
3311                                            const FieldDecl *field) {
3312   AlignmentSource fieldAlignSource =
3313     getFieldAlignmentSource(base.getAlignmentSource());
3314 
3315   if (field->isBitField()) {
3316     const CGRecordLayout &RL =
3317       CGM.getTypes().getCGRecordLayout(field->getParent());
3318     const CGBitFieldInfo &Info = RL.getBitFieldInfo(field);
3319     Address Addr = base.getAddress();
3320     unsigned Idx = RL.getLLVMFieldNo(field);
3321     if (Idx != 0)
3322       // For structs, we GEP to the field that the record layout suggests.
3323       Addr = Builder.CreateStructGEP(Addr, Idx, Info.StorageOffset,
3324                                      field->getName());
3325     // Get the access type.
3326     llvm::Type *FieldIntTy =
3327       llvm::Type::getIntNTy(getLLVMContext(), Info.StorageSize);
3328     if (Addr.getElementType() != FieldIntTy)
3329       Addr = Builder.CreateElementBitCast(Addr, FieldIntTy);
3330 
3331     QualType fieldType =
3332       field->getType().withCVRQualifiers(base.getVRQualifiers());
3333     return LValue::MakeBitfield(Addr, Info, fieldType, fieldAlignSource);
3334   }
3335 
3336   const RecordDecl *rec = field->getParent();
3337   QualType type = field->getType();
3338 
3339   bool mayAlias = rec->hasAttr<MayAliasAttr>();
3340 
3341   Address addr = base.getAddress();
3342   unsigned cvr = base.getVRQualifiers();
3343   bool TBAAPath = CGM.getCodeGenOpts().StructPathTBAA;
3344   if (rec->isUnion()) {
3345     // For unions, there is no pointer adjustment.
3346     assert(!type->isReferenceType() && "union has reference member");
3347     // TODO: handle path-aware TBAA for union.
3348     TBAAPath = false;
3349   } else {
3350     // For structs, we GEP to the field that the record layout suggests.
3351     addr = emitAddrOfFieldStorage(*this, addr, field);
3352 
3353     // If this is a reference field, load the reference right now.
3354     if (const ReferenceType *refType = type->getAs<ReferenceType>()) {
3355       llvm::LoadInst *load = Builder.CreateLoad(addr, "ref");
3356       if (cvr & Qualifiers::Volatile) load->setVolatile(true);
3357 
3358       // Loading the reference will disable path-aware TBAA.
3359       TBAAPath = false;
3360       if (CGM.shouldUseTBAA()) {
3361         llvm::MDNode *tbaa;
3362         if (mayAlias)
3363           tbaa = CGM.getTBAAInfo(getContext().CharTy);
3364         else
3365           tbaa = CGM.getTBAAInfo(type);
3366         if (tbaa)
3367           CGM.DecorateInstructionWithTBAA(load, tbaa);
3368       }
3369 
3370       mayAlias = false;
3371       type = refType->getPointeeType();
3372 
3373       CharUnits alignment =
3374         getNaturalTypeAlignment(type, &fieldAlignSource, /*pointee*/ true);
3375       addr = Address(load, alignment);
3376 
3377       // Qualifiers on the struct don't apply to the referencee, and
3378       // we'll pick up CVR from the actual type later, so reset these
3379       // additional qualifiers now.
3380       cvr = 0;
3381     }
3382   }
3383 
3384   // Make sure that the address is pointing to the right type.  This is critical
3385   // for both unions and structs.  A union needs a bitcast, a struct element
3386   // will need a bitcast if the LLVM type laid out doesn't match the desired
3387   // type.
3388   addr = Builder.CreateElementBitCast(addr,
3389                                       CGM.getTypes().ConvertTypeForMem(type),
3390                                       field->getName());
3391 
3392   if (field->hasAttr<AnnotateAttr>())
3393     addr = EmitFieldAnnotations(field, addr);
3394 
3395   LValue LV = MakeAddrLValue(addr, type, fieldAlignSource);
3396   LV.getQuals().addCVRQualifiers(cvr);
3397   if (TBAAPath) {
3398     const ASTRecordLayout &Layout =
3399         getContext().getASTRecordLayout(field->getParent());
3400     // Set the base type to be the base type of the base LValue and
3401     // update offset to be relative to the base type.
3402     LV.setTBAABaseType(mayAlias ? getContext().CharTy : base.getTBAABaseType());
3403     LV.setTBAAOffset(mayAlias ? 0 : base.getTBAAOffset() +
3404                      Layout.getFieldOffset(field->getFieldIndex()) /
3405                                            getContext().getCharWidth());
3406   }
3407 
3408   // __weak attribute on a field is ignored.
3409   if (LV.getQuals().getObjCGCAttr() == Qualifiers::Weak)
3410     LV.getQuals().removeObjCGCAttr();
3411 
3412   // Fields of may_alias structs act like 'char' for TBAA purposes.
3413   // FIXME: this should get propagated down through anonymous structs
3414   // and unions.
3415   if (mayAlias && LV.getTBAAInfo())
3416     LV.setTBAAInfo(CGM.getTBAAInfo(getContext().CharTy));
3417 
3418   return LV;
3419 }
3420 
3421 LValue
EmitLValueForFieldInitialization(LValue Base,const FieldDecl * Field)3422 CodeGenFunction::EmitLValueForFieldInitialization(LValue Base,
3423                                                   const FieldDecl *Field) {
3424   QualType FieldType = Field->getType();
3425 
3426   if (!FieldType->isReferenceType())
3427     return EmitLValueForField(Base, Field);
3428 
3429   Address V = emitAddrOfFieldStorage(*this, Base.getAddress(), Field);
3430 
3431   // Make sure that the address is pointing to the right type.
3432   llvm::Type *llvmType = ConvertTypeForMem(FieldType);
3433   V = Builder.CreateElementBitCast(V, llvmType, Field->getName());
3434 
3435   // TODO: access-path TBAA?
3436   auto FieldAlignSource = getFieldAlignmentSource(Base.getAlignmentSource());
3437   return MakeAddrLValue(V, FieldType, FieldAlignSource);
3438 }
3439 
EmitCompoundLiteralLValue(const CompoundLiteralExpr * E)3440 LValue CodeGenFunction::EmitCompoundLiteralLValue(const CompoundLiteralExpr *E){
3441   if (E->isFileScope()) {
3442     ConstantAddress GlobalPtr = CGM.GetAddrOfConstantCompoundLiteral(E);
3443     return MakeAddrLValue(GlobalPtr, E->getType(), AlignmentSource::Decl);
3444   }
3445   if (E->getType()->isVariablyModifiedType())
3446     // make sure to emit the VLA size.
3447     EmitVariablyModifiedType(E->getType());
3448 
3449   Address DeclPtr = CreateMemTemp(E->getType(), ".compoundliteral");
3450   const Expr *InitExpr = E->getInitializer();
3451   LValue Result = MakeAddrLValue(DeclPtr, E->getType(), AlignmentSource::Decl);
3452 
3453   EmitAnyExprToMem(InitExpr, DeclPtr, E->getType().getQualifiers(),
3454                    /*Init*/ true);
3455 
3456   return Result;
3457 }
3458 
EmitInitListLValue(const InitListExpr * E)3459 LValue CodeGenFunction::EmitInitListLValue(const InitListExpr *E) {
3460   if (!E->isGLValue())
3461     // Initializing an aggregate temporary in C++11: T{...}.
3462     return EmitAggExprToLValue(E);
3463 
3464   // An lvalue initializer list must be initializing a reference.
3465   assert(E->getNumInits() == 1 && "reference init with multiple values");
3466   return EmitLValue(E->getInit(0));
3467 }
3468 
3469 /// Emit the operand of a glvalue conditional operator. This is either a glvalue
3470 /// or a (possibly-parenthesized) throw-expression. If this is a throw, no
3471 /// LValue is returned and the current block has been terminated.
EmitLValueOrThrowExpression(CodeGenFunction & CGF,const Expr * Operand)3472 static Optional<LValue> EmitLValueOrThrowExpression(CodeGenFunction &CGF,
3473                                                     const Expr *Operand) {
3474   if (auto *ThrowExpr = dyn_cast<CXXThrowExpr>(Operand->IgnoreParens())) {
3475     CGF.EmitCXXThrowExpr(ThrowExpr, /*KeepInsertionPoint*/false);
3476     return None;
3477   }
3478 
3479   return CGF.EmitLValue(Operand);
3480 }
3481 
3482 LValue CodeGenFunction::
EmitConditionalOperatorLValue(const AbstractConditionalOperator * expr)3483 EmitConditionalOperatorLValue(const AbstractConditionalOperator *expr) {
3484   if (!expr->isGLValue()) {
3485     // ?: here should be an aggregate.
3486     assert(hasAggregateEvaluationKind(expr->getType()) &&
3487            "Unexpected conditional operator!");
3488     return EmitAggExprToLValue(expr);
3489   }
3490 
3491   OpaqueValueMapping binding(*this, expr);
3492 
3493   const Expr *condExpr = expr->getCond();
3494   bool CondExprBool;
3495   if (ConstantFoldsToSimpleInteger(condExpr, CondExprBool)) {
3496     const Expr *live = expr->getTrueExpr(), *dead = expr->getFalseExpr();
3497     if (!CondExprBool) std::swap(live, dead);
3498 
3499     if (!ContainsLabel(dead)) {
3500       // If the true case is live, we need to track its region.
3501       if (CondExprBool)
3502         incrementProfileCounter(expr);
3503       return EmitLValue(live);
3504     }
3505   }
3506 
3507   llvm::BasicBlock *lhsBlock = createBasicBlock("cond.true");
3508   llvm::BasicBlock *rhsBlock = createBasicBlock("cond.false");
3509   llvm::BasicBlock *contBlock = createBasicBlock("cond.end");
3510 
3511   ConditionalEvaluation eval(*this);
3512   EmitBranchOnBoolExpr(condExpr, lhsBlock, rhsBlock, getProfileCount(expr));
3513 
3514   // Any temporaries created here are conditional.
3515   EmitBlock(lhsBlock);
3516   incrementProfileCounter(expr);
3517   eval.begin(*this);
3518   Optional<LValue> lhs =
3519       EmitLValueOrThrowExpression(*this, expr->getTrueExpr());
3520   eval.end(*this);
3521 
3522   if (lhs && !lhs->isSimple())
3523     return EmitUnsupportedLValue(expr, "conditional operator");
3524 
3525   lhsBlock = Builder.GetInsertBlock();
3526   if (lhs)
3527     Builder.CreateBr(contBlock);
3528 
3529   // Any temporaries created here are conditional.
3530   EmitBlock(rhsBlock);
3531   eval.begin(*this);
3532   Optional<LValue> rhs =
3533       EmitLValueOrThrowExpression(*this, expr->getFalseExpr());
3534   eval.end(*this);
3535   if (rhs && !rhs->isSimple())
3536     return EmitUnsupportedLValue(expr, "conditional operator");
3537   rhsBlock = Builder.GetInsertBlock();
3538 
3539   EmitBlock(contBlock);
3540 
3541   if (lhs && rhs) {
3542     llvm::PHINode *phi = Builder.CreatePHI(lhs->getPointer()->getType(),
3543                                            2, "cond-lvalue");
3544     phi->addIncoming(lhs->getPointer(), lhsBlock);
3545     phi->addIncoming(rhs->getPointer(), rhsBlock);
3546     Address result(phi, std::min(lhs->getAlignment(), rhs->getAlignment()));
3547     AlignmentSource alignSource =
3548       std::max(lhs->getAlignmentSource(), rhs->getAlignmentSource());
3549     return MakeAddrLValue(result, expr->getType(), alignSource);
3550   } else {
3551     assert((lhs || rhs) &&
3552            "both operands of glvalue conditional are throw-expressions?");
3553     return lhs ? *lhs : *rhs;
3554   }
3555 }
3556 
3557 /// EmitCastLValue - Casts are never lvalues unless that cast is to a reference
3558 /// type. If the cast is to a reference, we can have the usual lvalue result,
3559 /// otherwise if a cast is needed by the code generator in an lvalue context,
3560 /// then it must mean that we need the address of an aggregate in order to
3561 /// access one of its members.  This can happen for all the reasons that casts
3562 /// are permitted with aggregate result, including noop aggregate casts, and
3563 /// cast from scalar to union.
EmitCastLValue(const CastExpr * E)3564 LValue CodeGenFunction::EmitCastLValue(const CastExpr *E) {
3565   switch (E->getCastKind()) {
3566   case CK_ToVoid:
3567   case CK_BitCast:
3568   case CK_ArrayToPointerDecay:
3569   case CK_FunctionToPointerDecay:
3570   case CK_NullToMemberPointer:
3571   case CK_NullToPointer:
3572   case CK_IntegralToPointer:
3573   case CK_PointerToIntegral:
3574   case CK_PointerToBoolean:
3575   case CK_VectorSplat:
3576   case CK_IntegralCast:
3577   case CK_BooleanToSignedIntegral:
3578   case CK_IntegralToBoolean:
3579   case CK_IntegralToFloating:
3580   case CK_FloatingToIntegral:
3581   case CK_FloatingToBoolean:
3582   case CK_FloatingCast:
3583   case CK_FloatingRealToComplex:
3584   case CK_FloatingComplexToReal:
3585   case CK_FloatingComplexToBoolean:
3586   case CK_FloatingComplexCast:
3587   case CK_FloatingComplexToIntegralComplex:
3588   case CK_IntegralRealToComplex:
3589   case CK_IntegralComplexToReal:
3590   case CK_IntegralComplexToBoolean:
3591   case CK_IntegralComplexCast:
3592   case CK_IntegralComplexToFloatingComplex:
3593   case CK_DerivedToBaseMemberPointer:
3594   case CK_BaseToDerivedMemberPointer:
3595   case CK_MemberPointerToBoolean:
3596   case CK_ReinterpretMemberPointer:
3597   case CK_AnyPointerToBlockPointerCast:
3598   case CK_ARCProduceObject:
3599   case CK_ARCConsumeObject:
3600   case CK_ARCReclaimReturnedObject:
3601   case CK_ARCExtendBlockObject:
3602   case CK_CopyAndAutoreleaseBlockObject:
3603   case CK_AddressSpaceConversion:
3604     return EmitUnsupportedLValue(E, "unexpected cast lvalue");
3605 
3606   case CK_Dependent:
3607     llvm_unreachable("dependent cast kind in IR gen!");
3608 
3609   case CK_BuiltinFnToFnPtr:
3610     llvm_unreachable("builtin functions are handled elsewhere");
3611 
3612   // These are never l-values; just use the aggregate emission code.
3613   case CK_NonAtomicToAtomic:
3614   case CK_AtomicToNonAtomic:
3615     return EmitAggExprToLValue(E);
3616 
3617   case CK_Dynamic: {
3618     LValue LV = EmitLValue(E->getSubExpr());
3619     Address V = LV.getAddress();
3620     const auto *DCE = cast<CXXDynamicCastExpr>(E);
3621     return MakeNaturalAlignAddrLValue(EmitDynamicCast(V, DCE), E->getType());
3622   }
3623 
3624   case CK_ConstructorConversion:
3625   case CK_UserDefinedConversion:
3626   case CK_CPointerToObjCPointerCast:
3627   case CK_BlockPointerToObjCPointerCast:
3628   case CK_NoOp:
3629   case CK_LValueToRValue:
3630     return EmitLValue(E->getSubExpr());
3631 
3632   case CK_UncheckedDerivedToBase:
3633   case CK_DerivedToBase: {
3634     const RecordType *DerivedClassTy =
3635       E->getSubExpr()->getType()->getAs<RecordType>();
3636     auto *DerivedClassDecl = cast<CXXRecordDecl>(DerivedClassTy->getDecl());
3637 
3638     LValue LV = EmitLValue(E->getSubExpr());
3639     Address This = LV.getAddress();
3640 
3641     // Perform the derived-to-base conversion
3642     Address Base = GetAddressOfBaseClass(
3643         This, DerivedClassDecl, E->path_begin(), E->path_end(),
3644         /*NullCheckValue=*/false, E->getExprLoc());
3645 
3646     return MakeAddrLValue(Base, E->getType(), LV.getAlignmentSource());
3647   }
3648   case CK_ToUnion:
3649     return EmitAggExprToLValue(E);
3650   case CK_BaseToDerived: {
3651     const RecordType *DerivedClassTy = E->getType()->getAs<RecordType>();
3652     auto *DerivedClassDecl = cast<CXXRecordDecl>(DerivedClassTy->getDecl());
3653 
3654     LValue LV = EmitLValue(E->getSubExpr());
3655 
3656     // Perform the base-to-derived conversion
3657     Address Derived =
3658       GetAddressOfDerivedClass(LV.getAddress(), DerivedClassDecl,
3659                                E->path_begin(), E->path_end(),
3660                                /*NullCheckValue=*/false);
3661 
3662     // C++11 [expr.static.cast]p2: Behavior is undefined if a downcast is
3663     // performed and the object is not of the derived type.
3664     if (sanitizePerformTypeCheck())
3665       EmitTypeCheck(TCK_DowncastReference, E->getExprLoc(),
3666                     Derived.getPointer(), E->getType());
3667 
3668     if (SanOpts.has(SanitizerKind::CFIDerivedCast))
3669       EmitVTablePtrCheckForCast(E->getType(), Derived.getPointer(),
3670                                 /*MayBeNull=*/false,
3671                                 CFITCK_DerivedCast, E->getLocStart());
3672 
3673     return MakeAddrLValue(Derived, E->getType(), LV.getAlignmentSource());
3674   }
3675   case CK_LValueBitCast: {
3676     // This must be a reinterpret_cast (or c-style equivalent).
3677     const auto *CE = cast<ExplicitCastExpr>(E);
3678 
3679     CGM.EmitExplicitCastExprType(CE, this);
3680     LValue LV = EmitLValue(E->getSubExpr());
3681     Address V = Builder.CreateBitCast(LV.getAddress(),
3682                                       ConvertType(CE->getTypeAsWritten()));
3683 
3684     if (SanOpts.has(SanitizerKind::CFIUnrelatedCast))
3685       EmitVTablePtrCheckForCast(E->getType(), V.getPointer(),
3686                                 /*MayBeNull=*/false,
3687                                 CFITCK_UnrelatedCast, E->getLocStart());
3688 
3689     return MakeAddrLValue(V, E->getType(), LV.getAlignmentSource());
3690   }
3691   case CK_ObjCObjectLValueCast: {
3692     LValue LV = EmitLValue(E->getSubExpr());
3693     Address V = Builder.CreateElementBitCast(LV.getAddress(),
3694                                              ConvertType(E->getType()));
3695     return MakeAddrLValue(V, E->getType(), LV.getAlignmentSource());
3696   }
3697   case CK_ZeroToOCLEvent:
3698     llvm_unreachable("NULL to OpenCL event lvalue cast is not valid");
3699   }
3700 
3701   llvm_unreachable("Unhandled lvalue cast kind?");
3702 }
3703 
EmitOpaqueValueLValue(const OpaqueValueExpr * e)3704 LValue CodeGenFunction::EmitOpaqueValueLValue(const OpaqueValueExpr *e) {
3705   assert(OpaqueValueMappingData::shouldBindAsLValue(e));
3706   return getOpaqueLValueMapping(e);
3707 }
3708 
EmitRValueForField(LValue LV,const FieldDecl * FD,SourceLocation Loc)3709 RValue CodeGenFunction::EmitRValueForField(LValue LV,
3710                                            const FieldDecl *FD,
3711                                            SourceLocation Loc) {
3712   QualType FT = FD->getType();
3713   LValue FieldLV = EmitLValueForField(LV, FD);
3714   switch (getEvaluationKind(FT)) {
3715   case TEK_Complex:
3716     return RValue::getComplex(EmitLoadOfComplex(FieldLV, Loc));
3717   case TEK_Aggregate:
3718     return FieldLV.asAggregateRValue();
3719   case TEK_Scalar:
3720     // This routine is used to load fields one-by-one to perform a copy, so
3721     // don't load reference fields.
3722     if (FD->getType()->isReferenceType())
3723       return RValue::get(FieldLV.getPointer());
3724     return EmitLoadOfLValue(FieldLV, Loc);
3725   }
3726   llvm_unreachable("bad evaluation kind");
3727 }
3728 
3729 //===--------------------------------------------------------------------===//
3730 //                             Expression Emission
3731 //===--------------------------------------------------------------------===//
3732 
EmitCallExpr(const CallExpr * E,ReturnValueSlot ReturnValue)3733 RValue CodeGenFunction::EmitCallExpr(const CallExpr *E,
3734                                      ReturnValueSlot ReturnValue) {
3735   // Builtins never have block type.
3736   if (E->getCallee()->getType()->isBlockPointerType())
3737     return EmitBlockCallExpr(E, ReturnValue);
3738 
3739   if (const auto *CE = dyn_cast<CXXMemberCallExpr>(E))
3740     return EmitCXXMemberCallExpr(CE, ReturnValue);
3741 
3742   if (const auto *CE = dyn_cast<CUDAKernelCallExpr>(E))
3743     return EmitCUDAKernelCallExpr(CE, ReturnValue);
3744 
3745   const Decl *TargetDecl = E->getCalleeDecl();
3746   if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(TargetDecl)) {
3747     if (unsigned builtinID = FD->getBuiltinID())
3748       return EmitBuiltinExpr(FD, builtinID, E, ReturnValue);
3749   }
3750 
3751   if (const auto *CE = dyn_cast<CXXOperatorCallExpr>(E))
3752     if (const CXXMethodDecl *MD = dyn_cast_or_null<CXXMethodDecl>(TargetDecl))
3753       return EmitCXXOperatorMemberCallExpr(CE, MD, ReturnValue);
3754 
3755   if (const auto *PseudoDtor =
3756           dyn_cast<CXXPseudoDestructorExpr>(E->getCallee()->IgnoreParens())) {
3757     QualType DestroyedType = PseudoDtor->getDestroyedType();
3758     if (DestroyedType.hasStrongOrWeakObjCLifetime()) {
3759       // Automatic Reference Counting:
3760       //   If the pseudo-expression names a retainable object with weak or
3761       //   strong lifetime, the object shall be released.
3762       Expr *BaseExpr = PseudoDtor->getBase();
3763       Address BaseValue = Address::invalid();
3764       Qualifiers BaseQuals;
3765 
3766       // If this is s.x, emit s as an lvalue. If it is s->x, emit s as a scalar.
3767       if (PseudoDtor->isArrow()) {
3768         BaseValue = EmitPointerWithAlignment(BaseExpr);
3769         const PointerType *PTy = BaseExpr->getType()->getAs<PointerType>();
3770         BaseQuals = PTy->getPointeeType().getQualifiers();
3771       } else {
3772         LValue BaseLV = EmitLValue(BaseExpr);
3773         BaseValue = BaseLV.getAddress();
3774         QualType BaseTy = BaseExpr->getType();
3775         BaseQuals = BaseTy.getQualifiers();
3776       }
3777 
3778       switch (DestroyedType.getObjCLifetime()) {
3779       case Qualifiers::OCL_None:
3780       case Qualifiers::OCL_ExplicitNone:
3781       case Qualifiers::OCL_Autoreleasing:
3782         break;
3783 
3784       case Qualifiers::OCL_Strong:
3785         EmitARCRelease(Builder.CreateLoad(BaseValue,
3786                           PseudoDtor->getDestroyedType().isVolatileQualified()),
3787                        ARCPreciseLifetime);
3788         break;
3789 
3790       case Qualifiers::OCL_Weak:
3791         EmitARCDestroyWeak(BaseValue);
3792         break;
3793       }
3794     } else {
3795       // C++ [expr.pseudo]p1:
3796       //   The result shall only be used as the operand for the function call
3797       //   operator (), and the result of such a call has type void. The only
3798       //   effect is the evaluation of the postfix-expression before the dot or
3799       //   arrow.
3800       EmitScalarExpr(E->getCallee());
3801     }
3802 
3803     return RValue::get(nullptr);
3804   }
3805 
3806   llvm::Value *Callee = EmitScalarExpr(E->getCallee());
3807   return EmitCall(E->getCallee()->getType(), Callee, E, ReturnValue,
3808                   TargetDecl);
3809 }
3810 
EmitBinaryOperatorLValue(const BinaryOperator * E)3811 LValue CodeGenFunction::EmitBinaryOperatorLValue(const BinaryOperator *E) {
3812   // Comma expressions just emit their LHS then their RHS as an l-value.
3813   if (E->getOpcode() == BO_Comma) {
3814     EmitIgnoredExpr(E->getLHS());
3815     EnsureInsertPoint();
3816     return EmitLValue(E->getRHS());
3817   }
3818 
3819   if (E->getOpcode() == BO_PtrMemD ||
3820       E->getOpcode() == BO_PtrMemI)
3821     return EmitPointerToDataMemberBinaryExpr(E);
3822 
3823   assert(E->getOpcode() == BO_Assign && "unexpected binary l-value");
3824 
3825   // Note that in all of these cases, __block variables need the RHS
3826   // evaluated first just in case the variable gets moved by the RHS.
3827 
3828   switch (getEvaluationKind(E->getType())) {
3829   case TEK_Scalar: {
3830     switch (E->getLHS()->getType().getObjCLifetime()) {
3831     case Qualifiers::OCL_Strong:
3832       return EmitARCStoreStrong(E, /*ignored*/ false).first;
3833 
3834     case Qualifiers::OCL_Autoreleasing:
3835       return EmitARCStoreAutoreleasing(E).first;
3836 
3837     // No reason to do any of these differently.
3838     case Qualifiers::OCL_None:
3839     case Qualifiers::OCL_ExplicitNone:
3840     case Qualifiers::OCL_Weak:
3841       break;
3842     }
3843 
3844     RValue RV = EmitAnyExpr(E->getRHS());
3845     LValue LV = EmitCheckedLValue(E->getLHS(), TCK_Store);
3846     EmitStoreThroughLValue(RV, LV);
3847     return LV;
3848   }
3849 
3850   case TEK_Complex:
3851     return EmitComplexAssignmentLValue(E);
3852 
3853   case TEK_Aggregate:
3854     return EmitAggExprToLValue(E);
3855   }
3856   llvm_unreachable("bad evaluation kind");
3857 }
3858 
EmitCallExprLValue(const CallExpr * E)3859 LValue CodeGenFunction::EmitCallExprLValue(const CallExpr *E) {
3860   RValue RV = EmitCallExpr(E);
3861 
3862   if (!RV.isScalar())
3863     return MakeAddrLValue(RV.getAggregateAddress(), E->getType(),
3864                           AlignmentSource::Decl);
3865 
3866   assert(E->getCallReturnType(getContext())->isReferenceType() &&
3867          "Can't have a scalar return unless the return type is a "
3868          "reference type!");
3869 
3870   return MakeNaturalAlignPointeeAddrLValue(RV.getScalarVal(), E->getType());
3871 }
3872 
EmitVAArgExprLValue(const VAArgExpr * E)3873 LValue CodeGenFunction::EmitVAArgExprLValue(const VAArgExpr *E) {
3874   // FIXME: This shouldn't require another copy.
3875   return EmitAggExprToLValue(E);
3876 }
3877 
EmitCXXConstructLValue(const CXXConstructExpr * E)3878 LValue CodeGenFunction::EmitCXXConstructLValue(const CXXConstructExpr *E) {
3879   assert(E->getType()->getAsCXXRecordDecl()->hasTrivialDestructor()
3880          && "binding l-value to type which needs a temporary");
3881   AggValueSlot Slot = CreateAggTemp(E->getType());
3882   EmitCXXConstructExpr(E, Slot);
3883   return MakeAddrLValue(Slot.getAddress(), E->getType(),
3884                         AlignmentSource::Decl);
3885 }
3886 
3887 LValue
EmitCXXTypeidLValue(const CXXTypeidExpr * E)3888 CodeGenFunction::EmitCXXTypeidLValue(const CXXTypeidExpr *E) {
3889   return MakeNaturalAlignAddrLValue(EmitCXXTypeidExpr(E), E->getType());
3890 }
3891 
EmitCXXUuidofExpr(const CXXUuidofExpr * E)3892 Address CodeGenFunction::EmitCXXUuidofExpr(const CXXUuidofExpr *E) {
3893   return Builder.CreateElementBitCast(CGM.GetAddrOfUuidDescriptor(E),
3894                                       ConvertType(E->getType()));
3895 }
3896 
EmitCXXUuidofLValue(const CXXUuidofExpr * E)3897 LValue CodeGenFunction::EmitCXXUuidofLValue(const CXXUuidofExpr *E) {
3898   return MakeAddrLValue(EmitCXXUuidofExpr(E), E->getType(),
3899                         AlignmentSource::Decl);
3900 }
3901 
3902 LValue
EmitCXXBindTemporaryLValue(const CXXBindTemporaryExpr * E)3903 CodeGenFunction::EmitCXXBindTemporaryLValue(const CXXBindTemporaryExpr *E) {
3904   AggValueSlot Slot = CreateAggTemp(E->getType(), "temp.lvalue");
3905   Slot.setExternallyDestructed();
3906   EmitAggExpr(E->getSubExpr(), Slot);
3907   EmitCXXTemporary(E->getTemporary(), E->getType(), Slot.getAddress());
3908   return MakeAddrLValue(Slot.getAddress(), E->getType(),
3909                         AlignmentSource::Decl);
3910 }
3911 
3912 LValue
EmitLambdaLValue(const LambdaExpr * E)3913 CodeGenFunction::EmitLambdaLValue(const LambdaExpr *E) {
3914   AggValueSlot Slot = CreateAggTemp(E->getType(), "temp.lvalue");
3915   EmitLambdaExpr(E, Slot);
3916   return MakeAddrLValue(Slot.getAddress(), E->getType(),
3917                         AlignmentSource::Decl);
3918 }
3919 
EmitObjCMessageExprLValue(const ObjCMessageExpr * E)3920 LValue CodeGenFunction::EmitObjCMessageExprLValue(const ObjCMessageExpr *E) {
3921   RValue RV = EmitObjCMessageExpr(E);
3922 
3923   if (!RV.isScalar())
3924     return MakeAddrLValue(RV.getAggregateAddress(), E->getType(),
3925                           AlignmentSource::Decl);
3926 
3927   assert(E->getMethodDecl()->getReturnType()->isReferenceType() &&
3928          "Can't have a scalar return unless the return type is a "
3929          "reference type!");
3930 
3931   return MakeNaturalAlignPointeeAddrLValue(RV.getScalarVal(), E->getType());
3932 }
3933 
EmitObjCSelectorLValue(const ObjCSelectorExpr * E)3934 LValue CodeGenFunction::EmitObjCSelectorLValue(const ObjCSelectorExpr *E) {
3935   Address V =
3936     CGM.getObjCRuntime().GetAddrOfSelector(*this, E->getSelector());
3937   return MakeAddrLValue(V, E->getType(), AlignmentSource::Decl);
3938 }
3939 
EmitIvarOffset(const ObjCInterfaceDecl * Interface,const ObjCIvarDecl * Ivar)3940 llvm::Value *CodeGenFunction::EmitIvarOffset(const ObjCInterfaceDecl *Interface,
3941                                              const ObjCIvarDecl *Ivar) {
3942   return CGM.getObjCRuntime().EmitIvarOffset(*this, Interface, Ivar);
3943 }
3944 
EmitLValueForIvar(QualType ObjectTy,llvm::Value * BaseValue,const ObjCIvarDecl * Ivar,unsigned CVRQualifiers)3945 LValue CodeGenFunction::EmitLValueForIvar(QualType ObjectTy,
3946                                           llvm::Value *BaseValue,
3947                                           const ObjCIvarDecl *Ivar,
3948                                           unsigned CVRQualifiers) {
3949   return CGM.getObjCRuntime().EmitObjCValueForIvar(*this, ObjectTy, BaseValue,
3950                                                    Ivar, CVRQualifiers);
3951 }
3952 
EmitObjCIvarRefLValue(const ObjCIvarRefExpr * E)3953 LValue CodeGenFunction::EmitObjCIvarRefLValue(const ObjCIvarRefExpr *E) {
3954   // FIXME: A lot of the code below could be shared with EmitMemberExpr.
3955   llvm::Value *BaseValue = nullptr;
3956   const Expr *BaseExpr = E->getBase();
3957   Qualifiers BaseQuals;
3958   QualType ObjectTy;
3959   if (E->isArrow()) {
3960     BaseValue = EmitScalarExpr(BaseExpr);
3961     ObjectTy = BaseExpr->getType()->getPointeeType();
3962     BaseQuals = ObjectTy.getQualifiers();
3963   } else {
3964     LValue BaseLV = EmitLValue(BaseExpr);
3965     BaseValue = BaseLV.getPointer();
3966     ObjectTy = BaseExpr->getType();
3967     BaseQuals = ObjectTy.getQualifiers();
3968   }
3969 
3970   LValue LV =
3971     EmitLValueForIvar(ObjectTy, BaseValue, E->getDecl(),
3972                       BaseQuals.getCVRQualifiers());
3973   setObjCGCLValueClass(getContext(), E, LV);
3974   return LV;
3975 }
3976 
EmitStmtExprLValue(const StmtExpr * E)3977 LValue CodeGenFunction::EmitStmtExprLValue(const StmtExpr *E) {
3978   // Can only get l-value for message expression returning aggregate type
3979   RValue RV = EmitAnyExprToTemp(E);
3980   return MakeAddrLValue(RV.getAggregateAddress(), E->getType(),
3981                         AlignmentSource::Decl);
3982 }
3983 
EmitCall(QualType CalleeType,llvm::Value * Callee,const CallExpr * E,ReturnValueSlot ReturnValue,CGCalleeInfo CalleeInfo,llvm::Value * Chain)3984 RValue CodeGenFunction::EmitCall(QualType CalleeType, llvm::Value *Callee,
3985                                  const CallExpr *E, ReturnValueSlot ReturnValue,
3986                                  CGCalleeInfo CalleeInfo, llvm::Value *Chain) {
3987   // Get the actual function type. The callee type will always be a pointer to
3988   // function type or a block pointer type.
3989   assert(CalleeType->isFunctionPointerType() &&
3990          "Call must have function pointer type!");
3991 
3992   // Preserve the non-canonical function type because things like exception
3993   // specifications disappear in the canonical type. That information is useful
3994   // to drive the generation of more accurate code for this call later on.
3995   const FunctionProtoType *NonCanonicalFTP = CalleeType->getAs<PointerType>()
3996                                                  ->getPointeeType()
3997                                                  ->getAs<FunctionProtoType>();
3998 
3999   const Decl *TargetDecl = CalleeInfo.getCalleeDecl();
4000 
4001   if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(TargetDecl))
4002     // We can only guarantee that a function is called from the correct
4003     // context/function based on the appropriate target attributes,
4004     // so only check in the case where we have both always_inline and target
4005     // since otherwise we could be making a conditional call after a check for
4006     // the proper cpu features (and it won't cause code generation issues due to
4007     // function based code generation).
4008     if (TargetDecl->hasAttr<AlwaysInlineAttr>() &&
4009         TargetDecl->hasAttr<TargetAttr>())
4010       checkTargetFeatures(E, FD);
4011 
4012   CalleeType = getContext().getCanonicalType(CalleeType);
4013 
4014   const auto *FnType =
4015       cast<FunctionType>(cast<PointerType>(CalleeType)->getPointeeType());
4016 
4017   if (getLangOpts().CPlusPlus && SanOpts.has(SanitizerKind::Function) &&
4018       (!TargetDecl || !isa<FunctionDecl>(TargetDecl))) {
4019     if (llvm::Constant *PrefixSig =
4020             CGM.getTargetCodeGenInfo().getUBSanFunctionSignature(CGM)) {
4021       SanitizerScope SanScope(this);
4022       llvm::Constant *FTRTTIConst =
4023           CGM.GetAddrOfRTTIDescriptor(QualType(FnType, 0), /*ForEH=*/true);
4024       llvm::Type *PrefixStructTyElems[] = {
4025         PrefixSig->getType(),
4026         FTRTTIConst->getType()
4027       };
4028       llvm::StructType *PrefixStructTy = llvm::StructType::get(
4029           CGM.getLLVMContext(), PrefixStructTyElems, /*isPacked=*/true);
4030 
4031       llvm::Value *CalleePrefixStruct = Builder.CreateBitCast(
4032           Callee, llvm::PointerType::getUnqual(PrefixStructTy));
4033       llvm::Value *CalleeSigPtr =
4034           Builder.CreateConstGEP2_32(PrefixStructTy, CalleePrefixStruct, 0, 0);
4035       llvm::Value *CalleeSig =
4036           Builder.CreateAlignedLoad(CalleeSigPtr, getIntAlign());
4037       llvm::Value *CalleeSigMatch = Builder.CreateICmpEQ(CalleeSig, PrefixSig);
4038 
4039       llvm::BasicBlock *Cont = createBasicBlock("cont");
4040       llvm::BasicBlock *TypeCheck = createBasicBlock("typecheck");
4041       Builder.CreateCondBr(CalleeSigMatch, TypeCheck, Cont);
4042 
4043       EmitBlock(TypeCheck);
4044       llvm::Value *CalleeRTTIPtr =
4045           Builder.CreateConstGEP2_32(PrefixStructTy, CalleePrefixStruct, 0, 1);
4046       llvm::Value *CalleeRTTI =
4047           Builder.CreateAlignedLoad(CalleeRTTIPtr, getPointerAlign());
4048       llvm::Value *CalleeRTTIMatch =
4049           Builder.CreateICmpEQ(CalleeRTTI, FTRTTIConst);
4050       llvm::Constant *StaticData[] = {
4051         EmitCheckSourceLocation(E->getLocStart()),
4052         EmitCheckTypeDescriptor(CalleeType)
4053       };
4054       EmitCheck(std::make_pair(CalleeRTTIMatch, SanitizerKind::Function),
4055                 "function_type_mismatch", StaticData, Callee);
4056 
4057       Builder.CreateBr(Cont);
4058       EmitBlock(Cont);
4059     }
4060   }
4061 
4062   // If we are checking indirect calls and this call is indirect, check that the
4063   // function pointer is a member of the bit set for the function type.
4064   if (SanOpts.has(SanitizerKind::CFIICall) &&
4065       (!TargetDecl || !isa<FunctionDecl>(TargetDecl))) {
4066     SanitizerScope SanScope(this);
4067     EmitSanitizerStatReport(llvm::SanStat_CFI_ICall);
4068 
4069     llvm::Metadata *MD = CGM.CreateMetadataIdentifierForType(QualType(FnType, 0));
4070     llvm::Value *TypeId = llvm::MetadataAsValue::get(getLLVMContext(), MD);
4071 
4072     llvm::Value *CastedCallee = Builder.CreateBitCast(Callee, Int8PtrTy);
4073     llvm::Value *TypeTest = Builder.CreateCall(
4074         CGM.getIntrinsic(llvm::Intrinsic::type_test), {CastedCallee, TypeId});
4075 
4076     auto CrossDsoTypeId = CGM.CreateCrossDsoCfiTypeId(MD);
4077     llvm::Constant *StaticData[] = {
4078         llvm::ConstantInt::get(Int8Ty, CFITCK_ICall),
4079         EmitCheckSourceLocation(E->getLocStart()),
4080         EmitCheckTypeDescriptor(QualType(FnType, 0)),
4081     };
4082     if (CGM.getCodeGenOpts().SanitizeCfiCrossDso && CrossDsoTypeId) {
4083       EmitCfiSlowPathCheck(SanitizerKind::CFIICall, TypeTest, CrossDsoTypeId,
4084                            CastedCallee, StaticData);
4085     } else {
4086       EmitCheck(std::make_pair(TypeTest, SanitizerKind::CFIICall),
4087                 "cfi_check_fail", StaticData,
4088                 {CastedCallee, llvm::UndefValue::get(IntPtrTy)});
4089     }
4090   }
4091 
4092   CallArgList Args;
4093   if (Chain)
4094     Args.add(RValue::get(Builder.CreateBitCast(Chain, CGM.VoidPtrTy)),
4095              CGM.getContext().VoidPtrTy);
4096   EmitCallArgs(Args, dyn_cast<FunctionProtoType>(FnType), E->arguments(),
4097                E->getDirectCallee(), /*ParamsToSkip*/ 0);
4098 
4099   const CGFunctionInfo &FnInfo = CGM.getTypes().arrangeFreeFunctionCall(
4100       Args, FnType, /*isChainCall=*/Chain);
4101 
4102   // C99 6.5.2.2p6:
4103   //   If the expression that denotes the called function has a type
4104   //   that does not include a prototype, [the default argument
4105   //   promotions are performed]. If the number of arguments does not
4106   //   equal the number of parameters, the behavior is undefined. If
4107   //   the function is defined with a type that includes a prototype,
4108   //   and either the prototype ends with an ellipsis (, ...) or the
4109   //   types of the arguments after promotion are not compatible with
4110   //   the types of the parameters, the behavior is undefined. If the
4111   //   function is defined with a type that does not include a
4112   //   prototype, and the types of the arguments after promotion are
4113   //   not compatible with those of the parameters after promotion,
4114   //   the behavior is undefined [except in some trivial cases].
4115   // That is, in the general case, we should assume that a call
4116   // through an unprototyped function type works like a *non-variadic*
4117   // call.  The way we make this work is to cast to the exact type
4118   // of the promoted arguments.
4119   //
4120   // Chain calls use this same code path to add the invisible chain parameter
4121   // to the function type.
4122   if (isa<FunctionNoProtoType>(FnType) || Chain) {
4123     llvm::Type *CalleeTy = getTypes().GetFunctionType(FnInfo);
4124     CalleeTy = CalleeTy->getPointerTo();
4125     Callee = Builder.CreateBitCast(Callee, CalleeTy, "callee.knr.cast");
4126   }
4127 
4128   return EmitCall(FnInfo, Callee, ReturnValue, Args,
4129                   CGCalleeInfo(NonCanonicalFTP, TargetDecl));
4130 }
4131 
4132 LValue CodeGenFunction::
EmitPointerToDataMemberBinaryExpr(const BinaryOperator * E)4133 EmitPointerToDataMemberBinaryExpr(const BinaryOperator *E) {
4134   Address BaseAddr = Address::invalid();
4135   if (E->getOpcode() == BO_PtrMemI) {
4136     BaseAddr = EmitPointerWithAlignment(E->getLHS());
4137   } else {
4138     BaseAddr = EmitLValue(E->getLHS()).getAddress();
4139   }
4140 
4141   llvm::Value *OffsetV = EmitScalarExpr(E->getRHS());
4142 
4143   const MemberPointerType *MPT
4144     = E->getRHS()->getType()->getAs<MemberPointerType>();
4145 
4146   AlignmentSource AlignSource;
4147   Address MemberAddr =
4148     EmitCXXMemberDataPointerAddress(E, BaseAddr, OffsetV, MPT,
4149                                     &AlignSource);
4150 
4151   return MakeAddrLValue(MemberAddr, MPT->getPointeeType(), AlignSource);
4152 }
4153 
4154 /// Given the address of a temporary variable, produce an r-value of
4155 /// its type.
convertTempToRValue(Address addr,QualType type,SourceLocation loc)4156 RValue CodeGenFunction::convertTempToRValue(Address addr,
4157                                             QualType type,
4158                                             SourceLocation loc) {
4159   LValue lvalue = MakeAddrLValue(addr, type, AlignmentSource::Decl);
4160   switch (getEvaluationKind(type)) {
4161   case TEK_Complex:
4162     return RValue::getComplex(EmitLoadOfComplex(lvalue, loc));
4163   case TEK_Aggregate:
4164     return lvalue.asAggregateRValue();
4165   case TEK_Scalar:
4166     return RValue::get(EmitLoadOfScalar(lvalue, loc));
4167   }
4168   llvm_unreachable("bad evaluation kind");
4169 }
4170 
SetFPAccuracy(llvm::Value * Val,float Accuracy)4171 void CodeGenFunction::SetFPAccuracy(llvm::Value *Val, float Accuracy) {
4172   assert(Val->getType()->isFPOrFPVectorTy());
4173   if (Accuracy == 0.0 || !isa<llvm::Instruction>(Val))
4174     return;
4175 
4176   llvm::MDBuilder MDHelper(getLLVMContext());
4177   llvm::MDNode *Node = MDHelper.createFPMath(Accuracy);
4178 
4179   cast<llvm::Instruction>(Val)->setMetadata(llvm::LLVMContext::MD_fpmath, Node);
4180 }
4181 
4182 namespace {
4183   struct LValueOrRValue {
4184     LValue LV;
4185     RValue RV;
4186   };
4187 }
4188 
emitPseudoObjectExpr(CodeGenFunction & CGF,const PseudoObjectExpr * E,bool forLValue,AggValueSlot slot)4189 static LValueOrRValue emitPseudoObjectExpr(CodeGenFunction &CGF,
4190                                            const PseudoObjectExpr *E,
4191                                            bool forLValue,
4192                                            AggValueSlot slot) {
4193   SmallVector<CodeGenFunction::OpaqueValueMappingData, 4> opaques;
4194 
4195   // Find the result expression, if any.
4196   const Expr *resultExpr = E->getResultExpr();
4197   LValueOrRValue result;
4198 
4199   for (PseudoObjectExpr::const_semantics_iterator
4200          i = E->semantics_begin(), e = E->semantics_end(); i != e; ++i) {
4201     const Expr *semantic = *i;
4202 
4203     // If this semantic expression is an opaque value, bind it
4204     // to the result of its source expression.
4205     if (const auto *ov = dyn_cast<OpaqueValueExpr>(semantic)) {
4206 
4207       // If this is the result expression, we may need to evaluate
4208       // directly into the slot.
4209       typedef CodeGenFunction::OpaqueValueMappingData OVMA;
4210       OVMA opaqueData;
4211       if (ov == resultExpr && ov->isRValue() && !forLValue &&
4212           CodeGenFunction::hasAggregateEvaluationKind(ov->getType())) {
4213         CGF.EmitAggExpr(ov->getSourceExpr(), slot);
4214 
4215         LValue LV = CGF.MakeAddrLValue(slot.getAddress(), ov->getType(),
4216                                        AlignmentSource::Decl);
4217         opaqueData = OVMA::bind(CGF, ov, LV);
4218         result.RV = slot.asRValue();
4219 
4220       // Otherwise, emit as normal.
4221       } else {
4222         opaqueData = OVMA::bind(CGF, ov, ov->getSourceExpr());
4223 
4224         // If this is the result, also evaluate the result now.
4225         if (ov == resultExpr) {
4226           if (forLValue)
4227             result.LV = CGF.EmitLValue(ov);
4228           else
4229             result.RV = CGF.EmitAnyExpr(ov, slot);
4230         }
4231       }
4232 
4233       opaques.push_back(opaqueData);
4234 
4235     // Otherwise, if the expression is the result, evaluate it
4236     // and remember the result.
4237     } else if (semantic == resultExpr) {
4238       if (forLValue)
4239         result.LV = CGF.EmitLValue(semantic);
4240       else
4241         result.RV = CGF.EmitAnyExpr(semantic, slot);
4242 
4243     // Otherwise, evaluate the expression in an ignored context.
4244     } else {
4245       CGF.EmitIgnoredExpr(semantic);
4246     }
4247   }
4248 
4249   // Unbind all the opaques now.
4250   for (unsigned i = 0, e = opaques.size(); i != e; ++i)
4251     opaques[i].unbind(CGF);
4252 
4253   return result;
4254 }
4255 
EmitPseudoObjectRValue(const PseudoObjectExpr * E,AggValueSlot slot)4256 RValue CodeGenFunction::EmitPseudoObjectRValue(const PseudoObjectExpr *E,
4257                                                AggValueSlot slot) {
4258   return emitPseudoObjectExpr(*this, E, false, slot).RV;
4259 }
4260 
EmitPseudoObjectLValue(const PseudoObjectExpr * E)4261 LValue CodeGenFunction::EmitPseudoObjectLValue(const PseudoObjectExpr *E) {
4262   return emitPseudoObjectExpr(*this, E, true, AggValueSlot::ignored()).LV;
4263 }
4264