1 //===--- CodeGenFunction.cpp - Emit LLVM Code from ASTs for a Function ----===//
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 coordinates the per-function state used while generating code.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "CodeGenFunction.h"
15 #include "CGCUDARuntime.h"
16 #include "CGCXXABI.h"
17 #include "CGDebugInfo.h"
18 #include "CodeGenModule.h"
19 #include "clang/AST/ASTContext.h"
20 #include "clang/AST/Decl.h"
21 #include "clang/AST/DeclCXX.h"
22 #include "clang/AST/StmtCXX.h"
23 #include "clang/Basic/TargetInfo.h"
24 #include "clang/Frontend/CodeGenOptions.h"
25 #include "llvm/IR/DataLayout.h"
26 #include "llvm/IR/Intrinsics.h"
27 #include "llvm/IR/MDBuilder.h"
28 #include "llvm/IR/Operator.h"
29 using namespace clang;
30 using namespace CodeGen;
31
CodeGenFunction(CodeGenModule & cgm,bool suppressNewContext)32 CodeGenFunction::CodeGenFunction(CodeGenModule &cgm, bool suppressNewContext)
33 : CodeGenTypeCache(cgm), CGM(cgm),
34 Target(CGM.getContext().getTargetInfo()),
35 Builder(cgm.getModule().getContext()),
36 SanitizePerformTypeCheck(CGM.getSanOpts().Null |
37 CGM.getSanOpts().Alignment |
38 CGM.getSanOpts().ObjectSize |
39 CGM.getSanOpts().Vptr),
40 SanOpts(&CGM.getSanOpts()),
41 AutoreleaseResult(false), BlockInfo(0), BlockPointer(0),
42 LambdaThisCaptureField(0), NormalCleanupDest(0), NextCleanupDestIndex(1),
43 FirstBlockInfo(0), EHResumeBlock(0), ExceptionSlot(0), EHSelectorSlot(0),
44 DebugInfo(0), DisableDebugInfo(false), DidCallStackSave(false),
45 IndirectBranch(0), SwitchInsn(0), CaseRangeBlock(0), UnreachableBlock(0),
46 CXXABIThisDecl(0), CXXABIThisValue(0), CXXThisValue(0),
47 CXXStructorImplicitParamDecl(0), CXXStructorImplicitParamValue(0),
48 OutermostConditional(0), TerminateLandingPad(0),
49 TerminateHandler(0), TrapBB(0) {
50 if (!suppressNewContext)
51 CGM.getCXXABI().getMangleContext().startNewFunction();
52
53 llvm::FastMathFlags FMF;
54 if (CGM.getLangOpts().FastMath)
55 FMF.setUnsafeAlgebra();
56 if (CGM.getLangOpts().FiniteMathOnly) {
57 FMF.setNoNaNs();
58 FMF.setNoInfs();
59 }
60 Builder.SetFastMathFlags(FMF);
61 }
62
~CodeGenFunction()63 CodeGenFunction::~CodeGenFunction() {
64 // If there are any unclaimed block infos, go ahead and destroy them
65 // now. This can happen if IR-gen gets clever and skips evaluating
66 // something.
67 if (FirstBlockInfo)
68 destroyBlockInfos(FirstBlockInfo);
69 }
70
71
ConvertTypeForMem(QualType T)72 llvm::Type *CodeGenFunction::ConvertTypeForMem(QualType T) {
73 return CGM.getTypes().ConvertTypeForMem(T);
74 }
75
ConvertType(QualType T)76 llvm::Type *CodeGenFunction::ConvertType(QualType T) {
77 return CGM.getTypes().ConvertType(T);
78 }
79
getEvaluationKind(QualType type)80 TypeEvaluationKind CodeGenFunction::getEvaluationKind(QualType type) {
81 type = type.getCanonicalType();
82 while (true) {
83 switch (type->getTypeClass()) {
84 #define TYPE(name, parent)
85 #define ABSTRACT_TYPE(name, parent)
86 #define NON_CANONICAL_TYPE(name, parent) case Type::name:
87 #define DEPENDENT_TYPE(name, parent) case Type::name:
88 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(name, parent) case Type::name:
89 #include "clang/AST/TypeNodes.def"
90 llvm_unreachable("non-canonical or dependent type in IR-generation");
91
92 // Various scalar types.
93 case Type::Builtin:
94 case Type::Pointer:
95 case Type::BlockPointer:
96 case Type::LValueReference:
97 case Type::RValueReference:
98 case Type::MemberPointer:
99 case Type::Vector:
100 case Type::ExtVector:
101 case Type::FunctionProto:
102 case Type::FunctionNoProto:
103 case Type::Enum:
104 case Type::ObjCObjectPointer:
105 return TEK_Scalar;
106
107 // Complexes.
108 case Type::Complex:
109 return TEK_Complex;
110
111 // Arrays, records, and Objective-C objects.
112 case Type::ConstantArray:
113 case Type::IncompleteArray:
114 case Type::VariableArray:
115 case Type::Record:
116 case Type::ObjCObject:
117 case Type::ObjCInterface:
118 return TEK_Aggregate;
119
120 // We operate on atomic values according to their underlying type.
121 case Type::Atomic:
122 type = cast<AtomicType>(type)->getValueType();
123 continue;
124 }
125 llvm_unreachable("unknown type kind!");
126 }
127 }
128
EmitReturnBlock()129 void CodeGenFunction::EmitReturnBlock() {
130 // For cleanliness, we try to avoid emitting the return block for
131 // simple cases.
132 llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
133
134 if (CurBB) {
135 assert(!CurBB->getTerminator() && "Unexpected terminated block.");
136
137 // We have a valid insert point, reuse it if it is empty or there are no
138 // explicit jumps to the return block.
139 if (CurBB->empty() || ReturnBlock.getBlock()->use_empty()) {
140 ReturnBlock.getBlock()->replaceAllUsesWith(CurBB);
141 delete ReturnBlock.getBlock();
142 } else
143 EmitBlock(ReturnBlock.getBlock());
144 return;
145 }
146
147 // Otherwise, if the return block is the target of a single direct
148 // branch then we can just put the code in that block instead. This
149 // cleans up functions which started with a unified return block.
150 if (ReturnBlock.getBlock()->hasOneUse()) {
151 llvm::BranchInst *BI =
152 dyn_cast<llvm::BranchInst>(*ReturnBlock.getBlock()->use_begin());
153 if (BI && BI->isUnconditional() &&
154 BI->getSuccessor(0) == ReturnBlock.getBlock()) {
155 // Reset insertion point, including debug location, and delete the
156 // branch. This is really subtle and only works because the next change
157 // in location will hit the caching in CGDebugInfo::EmitLocation and not
158 // override this.
159 Builder.SetCurrentDebugLocation(BI->getDebugLoc());
160 Builder.SetInsertPoint(BI->getParent());
161 BI->eraseFromParent();
162 delete ReturnBlock.getBlock();
163 return;
164 }
165 }
166
167 // FIXME: We are at an unreachable point, there is no reason to emit the block
168 // unless it has uses. However, we still need a place to put the debug
169 // region.end for now.
170
171 EmitBlock(ReturnBlock.getBlock());
172 }
173
EmitIfUsed(CodeGenFunction & CGF,llvm::BasicBlock * BB)174 static void EmitIfUsed(CodeGenFunction &CGF, llvm::BasicBlock *BB) {
175 if (!BB) return;
176 if (!BB->use_empty())
177 return CGF.CurFn->getBasicBlockList().push_back(BB);
178 delete BB;
179 }
180
FinishFunction(SourceLocation EndLoc)181 void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
182 assert(BreakContinueStack.empty() &&
183 "mismatched push/pop in break/continue stack!");
184
185 if (CGDebugInfo *DI = getDebugInfo())
186 DI->EmitLocation(Builder, EndLoc);
187
188 // Pop any cleanups that might have been associated with the
189 // parameters. Do this in whatever block we're currently in; it's
190 // important to do this before we enter the return block or return
191 // edges will be *really* confused.
192 if (EHStack.stable_begin() != PrologueCleanupDepth)
193 PopCleanupBlocks(PrologueCleanupDepth);
194
195 // Emit function epilog (to return).
196 EmitReturnBlock();
197
198 if (ShouldInstrumentFunction())
199 EmitFunctionInstrumentation("__cyg_profile_func_exit");
200
201 // Emit debug descriptor for function end.
202 if (CGDebugInfo *DI = getDebugInfo()) {
203 DI->EmitFunctionEnd(Builder);
204 }
205
206 EmitFunctionEpilog(*CurFnInfo);
207 EmitEndEHSpec(CurCodeDecl);
208
209 assert(EHStack.empty() &&
210 "did not remove all scopes from cleanup stack!");
211
212 // If someone did an indirect goto, emit the indirect goto block at the end of
213 // the function.
214 if (IndirectBranch) {
215 EmitBlock(IndirectBranch->getParent());
216 Builder.ClearInsertionPoint();
217 }
218
219 // Remove the AllocaInsertPt instruction, which is just a convenience for us.
220 llvm::Instruction *Ptr = AllocaInsertPt;
221 AllocaInsertPt = 0;
222 Ptr->eraseFromParent();
223
224 // If someone took the address of a label but never did an indirect goto, we
225 // made a zero entry PHI node, which is illegal, zap it now.
226 if (IndirectBranch) {
227 llvm::PHINode *PN = cast<llvm::PHINode>(IndirectBranch->getAddress());
228 if (PN->getNumIncomingValues() == 0) {
229 PN->replaceAllUsesWith(llvm::UndefValue::get(PN->getType()));
230 PN->eraseFromParent();
231 }
232 }
233
234 EmitIfUsed(*this, EHResumeBlock);
235 EmitIfUsed(*this, TerminateLandingPad);
236 EmitIfUsed(*this, TerminateHandler);
237 EmitIfUsed(*this, UnreachableBlock);
238
239 if (CGM.getCodeGenOpts().EmitDeclMetadata)
240 EmitDeclMetadata();
241 }
242
243 /// ShouldInstrumentFunction - Return true if the current function should be
244 /// instrumented with __cyg_profile_func_* calls
ShouldInstrumentFunction()245 bool CodeGenFunction::ShouldInstrumentFunction() {
246 if (!CGM.getCodeGenOpts().InstrumentFunctions)
247 return false;
248 if (!CurFuncDecl || CurFuncDecl->hasAttr<NoInstrumentFunctionAttr>())
249 return false;
250 return true;
251 }
252
253 /// EmitFunctionInstrumentation - Emit LLVM code to call the specified
254 /// instrumentation function with the current function and the call site, if
255 /// function instrumentation is enabled.
EmitFunctionInstrumentation(const char * Fn)256 void CodeGenFunction::EmitFunctionInstrumentation(const char *Fn) {
257 // void __cyg_profile_func_{enter,exit} (void *this_fn, void *call_site);
258 llvm::PointerType *PointerTy = Int8PtrTy;
259 llvm::Type *ProfileFuncArgs[] = { PointerTy, PointerTy };
260 llvm::FunctionType *FunctionTy =
261 llvm::FunctionType::get(VoidTy, ProfileFuncArgs, false);
262
263 llvm::Constant *F = CGM.CreateRuntimeFunction(FunctionTy, Fn);
264 llvm::CallInst *CallSite = Builder.CreateCall(
265 CGM.getIntrinsic(llvm::Intrinsic::returnaddress),
266 llvm::ConstantInt::get(Int32Ty, 0),
267 "callsite");
268
269 llvm::Value *args[] = {
270 llvm::ConstantExpr::getBitCast(CurFn, PointerTy),
271 CallSite
272 };
273
274 EmitNounwindRuntimeCall(F, args);
275 }
276
EmitMCountInstrumentation()277 void CodeGenFunction::EmitMCountInstrumentation() {
278 llvm::FunctionType *FTy = llvm::FunctionType::get(VoidTy, false);
279
280 llvm::Constant *MCountFn = CGM.CreateRuntimeFunction(FTy,
281 Target.getMCountName());
282 EmitNounwindRuntimeCall(MCountFn);
283 }
284
285 // OpenCL v1.2 s5.6.4.6 allows the compiler to store kernel argument
286 // information in the program executable. The argument information stored
287 // includes the argument name, its type, the address and access qualifiers used.
288 // FIXME: Add type, address, and access qualifiers.
GenOpenCLArgMetadata(const FunctionDecl * FD,llvm::Function * Fn,CodeGenModule & CGM,llvm::LLVMContext & Context,SmallVector<llvm::Value *,5> & kernelMDArgs)289 static void GenOpenCLArgMetadata(const FunctionDecl *FD, llvm::Function *Fn,
290 CodeGenModule &CGM,llvm::LLVMContext &Context,
291 SmallVector <llvm::Value*, 5> &kernelMDArgs) {
292
293 // Create MDNodes that represents the kernel arg metadata.
294 // Each MDNode is a list in the form of "key", N number of values which is
295 // the same number of values as their are kernel arguments.
296
297 // MDNode for the kernel argument names.
298 SmallVector<llvm::Value*, 8> argNames;
299 argNames.push_back(llvm::MDString::get(Context, "kernel_arg_name"));
300
301 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i) {
302 const ParmVarDecl *parm = FD->getParamDecl(i);
303
304 // Get argument name.
305 argNames.push_back(llvm::MDString::get(Context, parm->getName()));
306
307 }
308 // Add MDNode to the list of all metadata.
309 kernelMDArgs.push_back(llvm::MDNode::get(Context, argNames));
310 }
311
EmitOpenCLKernelMetadata(const FunctionDecl * FD,llvm::Function * Fn)312 void CodeGenFunction::EmitOpenCLKernelMetadata(const FunctionDecl *FD,
313 llvm::Function *Fn)
314 {
315 if (!FD->hasAttr<OpenCLKernelAttr>())
316 return;
317
318 llvm::LLVMContext &Context = getLLVMContext();
319
320 SmallVector <llvm::Value*, 5> kernelMDArgs;
321 kernelMDArgs.push_back(Fn);
322
323 if (CGM.getCodeGenOpts().EmitOpenCLArgMetadata)
324 GenOpenCLArgMetadata(FD, Fn, CGM, Context, kernelMDArgs);
325
326 if (FD->hasAttr<VecTypeHintAttr>()) {
327 VecTypeHintAttr *attr = FD->getAttr<VecTypeHintAttr>();
328 QualType hintQTy = attr->getTypeHint();
329 const ExtVectorType *hintEltQTy = hintQTy->getAs<ExtVectorType>();
330 bool isSignedInteger =
331 hintQTy->isSignedIntegerType() ||
332 (hintEltQTy && hintEltQTy->getElementType()->isSignedIntegerType());
333 llvm::Value *attrMDArgs[] = {
334 llvm::MDString::get(Context, "vec_type_hint"),
335 llvm::UndefValue::get(CGM.getTypes().ConvertType(attr->getTypeHint())),
336 llvm::ConstantInt::get(
337 llvm::IntegerType::get(Context, 32),
338 llvm::APInt(32, (uint64_t)(isSignedInteger ? 1 : 0)))
339 };
340 kernelMDArgs.push_back(llvm::MDNode::get(Context, attrMDArgs));
341 }
342
343 if (FD->hasAttr<WorkGroupSizeHintAttr>()) {
344 WorkGroupSizeHintAttr *attr = FD->getAttr<WorkGroupSizeHintAttr>();
345 llvm::Value *attrMDArgs[] = {
346 llvm::MDString::get(Context, "work_group_size_hint"),
347 Builder.getInt32(attr->getXDim()),
348 Builder.getInt32(attr->getYDim()),
349 Builder.getInt32(attr->getZDim())
350 };
351 kernelMDArgs.push_back(llvm::MDNode::get(Context, attrMDArgs));
352 }
353
354 if (FD->hasAttr<ReqdWorkGroupSizeAttr>()) {
355 ReqdWorkGroupSizeAttr *attr = FD->getAttr<ReqdWorkGroupSizeAttr>();
356 llvm::Value *attrMDArgs[] = {
357 llvm::MDString::get(Context, "reqd_work_group_size"),
358 Builder.getInt32(attr->getXDim()),
359 Builder.getInt32(attr->getYDim()),
360 Builder.getInt32(attr->getZDim())
361 };
362 kernelMDArgs.push_back(llvm::MDNode::get(Context, attrMDArgs));
363 }
364
365 llvm::MDNode *kernelMDNode = llvm::MDNode::get(Context, kernelMDArgs);
366 llvm::NamedMDNode *OpenCLKernelMetadata =
367 CGM.getModule().getOrInsertNamedMetadata("opencl.kernels");
368 OpenCLKernelMetadata->addOperand(kernelMDNode);
369 }
370
StartFunction(GlobalDecl GD,QualType RetTy,llvm::Function * Fn,const CGFunctionInfo & FnInfo,const FunctionArgList & Args,SourceLocation StartLoc)371 void CodeGenFunction::StartFunction(GlobalDecl GD, QualType RetTy,
372 llvm::Function *Fn,
373 const CGFunctionInfo &FnInfo,
374 const FunctionArgList &Args,
375 SourceLocation StartLoc) {
376 const Decl *D = GD.getDecl();
377
378 DidCallStackSave = false;
379 CurCodeDecl = CurFuncDecl = D;
380 FnRetTy = RetTy;
381 CurFn = Fn;
382 CurFnInfo = &FnInfo;
383 assert(CurFn->isDeclaration() && "Function already has body?");
384
385 if (CGM.getSanitizerBlacklist().isIn(*Fn)) {
386 SanOpts = &SanitizerOptions::Disabled;
387 SanitizePerformTypeCheck = false;
388 }
389
390 // Pass inline keyword to optimizer if it appears explicitly on any
391 // declaration.
392 if (!CGM.getCodeGenOpts().NoInline)
393 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
394 for (FunctionDecl::redecl_iterator RI = FD->redecls_begin(),
395 RE = FD->redecls_end(); RI != RE; ++RI)
396 if (RI->isInlineSpecified()) {
397 Fn->addFnAttr(llvm::Attribute::InlineHint);
398 break;
399 }
400
401 if (getLangOpts().OpenCL) {
402 // Add metadata for a kernel function.
403 if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D))
404 EmitOpenCLKernelMetadata(FD, Fn);
405 }
406
407 llvm::BasicBlock *EntryBB = createBasicBlock("entry", CurFn);
408
409 // Create a marker to make it easy to insert allocas into the entryblock
410 // later. Don't create this with the builder, because we don't want it
411 // folded.
412 llvm::Value *Undef = llvm::UndefValue::get(Int32Ty);
413 AllocaInsertPt = new llvm::BitCastInst(Undef, Int32Ty, "", EntryBB);
414 if (Builder.isNamePreserving())
415 AllocaInsertPt->setName("allocapt");
416
417 ReturnBlock = getJumpDestInCurrentScope("return");
418
419 Builder.SetInsertPoint(EntryBB);
420
421 // Emit subprogram debug descriptor.
422 if (CGDebugInfo *DI = getDebugInfo()) {
423 SmallVector<QualType, 16> ArgTypes;
424 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
425 i != e; ++i) {
426 ArgTypes.push_back((*i)->getType());
427 }
428
429 QualType FnType =
430 getContext().getFunctionType(RetTy, ArgTypes,
431 FunctionProtoType::ExtProtoInfo());
432
433 DI->setLocation(StartLoc);
434 DI->EmitFunctionStart(GD, FnType, CurFn, Builder);
435 }
436
437 if (ShouldInstrumentFunction())
438 EmitFunctionInstrumentation("__cyg_profile_func_enter");
439
440 if (CGM.getCodeGenOpts().InstrumentForProfiling)
441 EmitMCountInstrumentation();
442
443 if (RetTy->isVoidType()) {
444 // Void type; nothing to return.
445 ReturnValue = 0;
446 } else if (CurFnInfo->getReturnInfo().getKind() == ABIArgInfo::Indirect &&
447 !hasScalarEvaluationKind(CurFnInfo->getReturnType())) {
448 // Indirect aggregate return; emit returned value directly into sret slot.
449 // This reduces code size, and affects correctness in C++.
450 ReturnValue = CurFn->arg_begin();
451 } else {
452 ReturnValue = CreateIRTemp(RetTy, "retval");
453
454 // Tell the epilog emitter to autorelease the result. We do this
455 // now so that various specialized functions can suppress it
456 // during their IR-generation.
457 if (getLangOpts().ObjCAutoRefCount &&
458 !CurFnInfo->isReturnsRetained() &&
459 RetTy->isObjCRetainableType())
460 AutoreleaseResult = true;
461 }
462
463 EmitStartEHSpec(CurCodeDecl);
464
465 PrologueCleanupDepth = EHStack.stable_begin();
466 EmitFunctionProlog(*CurFnInfo, CurFn, Args);
467
468 if (D && isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance()) {
469 CGM.getCXXABI().EmitInstanceFunctionProlog(*this);
470 const CXXMethodDecl *MD = cast<CXXMethodDecl>(D);
471 if (MD->getParent()->isLambda() &&
472 MD->getOverloadedOperator() == OO_Call) {
473 // We're in a lambda; figure out the captures.
474 MD->getParent()->getCaptureFields(LambdaCaptureFields,
475 LambdaThisCaptureField);
476 if (LambdaThisCaptureField) {
477 // If this lambda captures this, load it.
478 QualType LambdaTagType =
479 getContext().getTagDeclType(LambdaThisCaptureField->getParent());
480 LValue LambdaLV = MakeNaturalAlignAddrLValue(CXXABIThisValue,
481 LambdaTagType);
482 LValue ThisLValue = EmitLValueForField(LambdaLV,
483 LambdaThisCaptureField);
484 CXXThisValue = EmitLoadOfLValue(ThisLValue).getScalarVal();
485 }
486 } else {
487 // Not in a lambda; just use 'this' from the method.
488 // FIXME: Should we generate a new load for each use of 'this'? The
489 // fast register allocator would be happier...
490 CXXThisValue = CXXABIThisValue;
491 }
492 }
493
494 // If any of the arguments have a variably modified type, make sure to
495 // emit the type size.
496 for (FunctionArgList::const_iterator i = Args.begin(), e = Args.end();
497 i != e; ++i) {
498 const VarDecl *VD = *i;
499
500 // Dig out the type as written from ParmVarDecls; it's unclear whether
501 // the standard (C99 6.9.1p10) requires this, but we're following the
502 // precedent set by gcc.
503 QualType Ty;
504 if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD))
505 Ty = PVD->getOriginalType();
506 else
507 Ty = VD->getType();
508
509 if (Ty->isVariablyModifiedType())
510 EmitVariablyModifiedType(Ty);
511 }
512 // Emit a location at the end of the prologue.
513 if (CGDebugInfo *DI = getDebugInfo())
514 DI->EmitLocation(Builder, StartLoc);
515 }
516
EmitFunctionBody(FunctionArgList & Args)517 void CodeGenFunction::EmitFunctionBody(FunctionArgList &Args) {
518 const FunctionDecl *FD = cast<FunctionDecl>(CurGD.getDecl());
519 assert(FD->getBody());
520 if (const CompoundStmt *S = dyn_cast<CompoundStmt>(FD->getBody()))
521 EmitCompoundStmtWithoutScope(*S);
522 else
523 EmitStmt(FD->getBody());
524 }
525
526 /// Tries to mark the given function nounwind based on the
527 /// non-existence of any throwing calls within it. We believe this is
528 /// lightweight enough to do at -O0.
TryMarkNoThrow(llvm::Function * F)529 static void TryMarkNoThrow(llvm::Function *F) {
530 // LLVM treats 'nounwind' on a function as part of the type, so we
531 // can't do this on functions that can be overwritten.
532 if (F->mayBeOverridden()) return;
533
534 for (llvm::Function::iterator FI = F->begin(), FE = F->end(); FI != FE; ++FI)
535 for (llvm::BasicBlock::iterator
536 BI = FI->begin(), BE = FI->end(); BI != BE; ++BI)
537 if (llvm::CallInst *Call = dyn_cast<llvm::CallInst>(&*BI)) {
538 if (!Call->doesNotThrow())
539 return;
540 } else if (isa<llvm::ResumeInst>(&*BI)) {
541 return;
542 }
543 F->setDoesNotThrow();
544 }
545
GenerateCode(GlobalDecl GD,llvm::Function * Fn,const CGFunctionInfo & FnInfo)546 void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
547 const CGFunctionInfo &FnInfo) {
548 const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
549
550 // Check if we should generate debug info for this function.
551 if (!FD->hasAttr<NoDebugAttr>())
552 maybeInitializeDebugInfo();
553
554 FunctionArgList Args;
555 QualType ResTy = FD->getResultType();
556
557 CurGD = GD;
558 if (isa<CXXMethodDecl>(FD) && cast<CXXMethodDecl>(FD)->isInstance())
559 CGM.getCXXABI().BuildInstanceFunctionParams(*this, ResTy, Args);
560
561 for (unsigned i = 0, e = FD->getNumParams(); i != e; ++i)
562 Args.push_back(FD->getParamDecl(i));
563
564 SourceRange BodyRange;
565 if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange();
566
567 // Emit the standard function prologue.
568 StartFunction(GD, ResTy, Fn, FnInfo, Args, BodyRange.getBegin());
569
570 // Generate the body of the function.
571 if (isa<CXXDestructorDecl>(FD))
572 EmitDestructorBody(Args);
573 else if (isa<CXXConstructorDecl>(FD))
574 EmitConstructorBody(Args);
575 else if (getLangOpts().CUDA &&
576 !CGM.getCodeGenOpts().CUDAIsDevice &&
577 FD->hasAttr<CUDAGlobalAttr>())
578 CGM.getCUDARuntime().EmitDeviceStubBody(*this, Args);
579 else if (isa<CXXConversionDecl>(FD) &&
580 cast<CXXConversionDecl>(FD)->isLambdaToBlockPointerConversion()) {
581 // The lambda conversion to block pointer is special; the semantics can't be
582 // expressed in the AST, so IRGen needs to special-case it.
583 EmitLambdaToBlockPointerBody(Args);
584 } else if (isa<CXXMethodDecl>(FD) &&
585 cast<CXXMethodDecl>(FD)->isLambdaStaticInvoker()) {
586 // The lambda "__invoke" function is special, because it forwards or
587 // clones the body of the function call operator (but is actually static).
588 EmitLambdaStaticInvokeFunction(cast<CXXMethodDecl>(FD));
589 } else if (FD->isDefaulted() && isa<CXXMethodDecl>(FD) &&
590 cast<CXXMethodDecl>(FD)->isCopyAssignmentOperator()) {
591 // Implicit copy-assignment gets the same special treatment as implicit
592 // copy-constructors.
593 emitImplicitAssignmentOperatorBody(Args);
594 }
595 else
596 EmitFunctionBody(Args);
597
598 // C++11 [stmt.return]p2:
599 // Flowing off the end of a function [...] results in undefined behavior in
600 // a value-returning function.
601 // C11 6.9.1p12:
602 // If the '}' that terminates a function is reached, and the value of the
603 // function call is used by the caller, the behavior is undefined.
604 if (getLangOpts().CPlusPlus && !FD->hasImplicitReturnZero() &&
605 !FD->getResultType()->isVoidType() && Builder.GetInsertBlock()) {
606 if (SanOpts->Return)
607 EmitCheck(Builder.getFalse(), "missing_return",
608 EmitCheckSourceLocation(FD->getLocation()),
609 ArrayRef<llvm::Value *>(), CRK_Unrecoverable);
610 else if (CGM.getCodeGenOpts().OptimizationLevel == 0)
611 Builder.CreateCall(CGM.getIntrinsic(llvm::Intrinsic::trap));
612 Builder.CreateUnreachable();
613 Builder.ClearInsertionPoint();
614 }
615
616 // Emit the standard function epilogue.
617 FinishFunction(BodyRange.getEnd());
618
619 // If we haven't marked the function nothrow through other means, do
620 // a quick pass now to see if we can.
621 if (!CurFn->doesNotThrow())
622 TryMarkNoThrow(CurFn);
623 }
624
625 /// ContainsLabel - Return true if the statement contains a label in it. If
626 /// this statement is not executed normally, it not containing a label means
627 /// that we can just remove the code.
ContainsLabel(const Stmt * S,bool IgnoreCaseStmts)628 bool CodeGenFunction::ContainsLabel(const Stmt *S, bool IgnoreCaseStmts) {
629 // Null statement, not a label!
630 if (S == 0) return false;
631
632 // If this is a label, we have to emit the code, consider something like:
633 // if (0) { ... foo: bar(); } goto foo;
634 //
635 // TODO: If anyone cared, we could track __label__'s, since we know that you
636 // can't jump to one from outside their declared region.
637 if (isa<LabelStmt>(S))
638 return true;
639
640 // If this is a case/default statement, and we haven't seen a switch, we have
641 // to emit the code.
642 if (isa<SwitchCase>(S) && !IgnoreCaseStmts)
643 return true;
644
645 // If this is a switch statement, we want to ignore cases below it.
646 if (isa<SwitchStmt>(S))
647 IgnoreCaseStmts = true;
648
649 // Scan subexpressions for verboten labels.
650 for (Stmt::const_child_range I = S->children(); I; ++I)
651 if (ContainsLabel(*I, IgnoreCaseStmts))
652 return true;
653
654 return false;
655 }
656
657 /// containsBreak - Return true if the statement contains a break out of it.
658 /// If the statement (recursively) contains a switch or loop with a break
659 /// inside of it, this is fine.
containsBreak(const Stmt * S)660 bool CodeGenFunction::containsBreak(const Stmt *S) {
661 // Null statement, not a label!
662 if (S == 0) return false;
663
664 // If this is a switch or loop that defines its own break scope, then we can
665 // include it and anything inside of it.
666 if (isa<SwitchStmt>(S) || isa<WhileStmt>(S) || isa<DoStmt>(S) ||
667 isa<ForStmt>(S))
668 return false;
669
670 if (isa<BreakStmt>(S))
671 return true;
672
673 // Scan subexpressions for verboten breaks.
674 for (Stmt::const_child_range I = S->children(); I; ++I)
675 if (containsBreak(*I))
676 return true;
677
678 return false;
679 }
680
681
682 /// ConstantFoldsToSimpleInteger - If the specified expression does not fold
683 /// to a constant, or if it does but contains a label, return false. If it
684 /// constant folds return true and set the boolean result in Result.
ConstantFoldsToSimpleInteger(const Expr * Cond,bool & ResultBool)685 bool CodeGenFunction::ConstantFoldsToSimpleInteger(const Expr *Cond,
686 bool &ResultBool) {
687 llvm::APSInt ResultInt;
688 if (!ConstantFoldsToSimpleInteger(Cond, ResultInt))
689 return false;
690
691 ResultBool = ResultInt.getBoolValue();
692 return true;
693 }
694
695 /// ConstantFoldsToSimpleInteger - If the specified expression does not fold
696 /// to a constant, or if it does but contains a label, return false. If it
697 /// constant folds return true and set the folded value.
698 bool CodeGenFunction::
ConstantFoldsToSimpleInteger(const Expr * Cond,llvm::APSInt & ResultInt)699 ConstantFoldsToSimpleInteger(const Expr *Cond, llvm::APSInt &ResultInt) {
700 // FIXME: Rename and handle conversion of other evaluatable things
701 // to bool.
702 llvm::APSInt Int;
703 if (!Cond->EvaluateAsInt(Int, getContext()))
704 return false; // Not foldable, not integer or not fully evaluatable.
705
706 if (CodeGenFunction::ContainsLabel(Cond))
707 return false; // Contains a label.
708
709 ResultInt = Int;
710 return true;
711 }
712
713
714
715 /// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if
716 /// statement) to the specified blocks. Based on the condition, this might try
717 /// to simplify the codegen of the conditional based on the branch.
718 ///
EmitBranchOnBoolExpr(const Expr * Cond,llvm::BasicBlock * TrueBlock,llvm::BasicBlock * FalseBlock)719 void CodeGenFunction::EmitBranchOnBoolExpr(const Expr *Cond,
720 llvm::BasicBlock *TrueBlock,
721 llvm::BasicBlock *FalseBlock) {
722 Cond = Cond->IgnoreParens();
723
724 if (const BinaryOperator *CondBOp = dyn_cast<BinaryOperator>(Cond)) {
725 // Handle X && Y in a condition.
726 if (CondBOp->getOpcode() == BO_LAnd) {
727 // If we have "1 && X", simplify the code. "0 && X" would have constant
728 // folded if the case was simple enough.
729 bool ConstantBool = false;
730 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) &&
731 ConstantBool) {
732 // br(1 && X) -> br(X).
733 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
734 }
735
736 // If we have "X && 1", simplify the code to use an uncond branch.
737 // "X && 0" would have been constant folded to 0.
738 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) &&
739 ConstantBool) {
740 // br(X && 1) -> br(X).
741 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
742 }
743
744 // Emit the LHS as a conditional. If the LHS conditional is false, we
745 // want to jump to the FalseBlock.
746 llvm::BasicBlock *LHSTrue = createBasicBlock("land.lhs.true");
747
748 ConditionalEvaluation eval(*this);
749 EmitBranchOnBoolExpr(CondBOp->getLHS(), LHSTrue, FalseBlock);
750 EmitBlock(LHSTrue);
751
752 // Any temporaries created here are conditional.
753 eval.begin(*this);
754 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
755 eval.end(*this);
756
757 return;
758 }
759
760 if (CondBOp->getOpcode() == BO_LOr) {
761 // If we have "0 || X", simplify the code. "1 || X" would have constant
762 // folded if the case was simple enough.
763 bool ConstantBool = false;
764 if (ConstantFoldsToSimpleInteger(CondBOp->getLHS(), ConstantBool) &&
765 !ConstantBool) {
766 // br(0 || X) -> br(X).
767 return EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
768 }
769
770 // If we have "X || 0", simplify the code to use an uncond branch.
771 // "X || 1" would have been constant folded to 1.
772 if (ConstantFoldsToSimpleInteger(CondBOp->getRHS(), ConstantBool) &&
773 !ConstantBool) {
774 // br(X || 0) -> br(X).
775 return EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, FalseBlock);
776 }
777
778 // Emit the LHS as a conditional. If the LHS conditional is true, we
779 // want to jump to the TrueBlock.
780 llvm::BasicBlock *LHSFalse = createBasicBlock("lor.lhs.false");
781
782 ConditionalEvaluation eval(*this);
783 EmitBranchOnBoolExpr(CondBOp->getLHS(), TrueBlock, LHSFalse);
784 EmitBlock(LHSFalse);
785
786 // Any temporaries created here are conditional.
787 eval.begin(*this);
788 EmitBranchOnBoolExpr(CondBOp->getRHS(), TrueBlock, FalseBlock);
789 eval.end(*this);
790
791 return;
792 }
793 }
794
795 if (const UnaryOperator *CondUOp = dyn_cast<UnaryOperator>(Cond)) {
796 // br(!x, t, f) -> br(x, f, t)
797 if (CondUOp->getOpcode() == UO_LNot)
798 return EmitBranchOnBoolExpr(CondUOp->getSubExpr(), FalseBlock, TrueBlock);
799 }
800
801 if (const ConditionalOperator *CondOp = dyn_cast<ConditionalOperator>(Cond)) {
802 // br(c ? x : y, t, f) -> br(c, br(x, t, f), br(y, t, f))
803 llvm::BasicBlock *LHSBlock = createBasicBlock("cond.true");
804 llvm::BasicBlock *RHSBlock = createBasicBlock("cond.false");
805
806 ConditionalEvaluation cond(*this);
807 EmitBranchOnBoolExpr(CondOp->getCond(), LHSBlock, RHSBlock);
808
809 cond.begin(*this);
810 EmitBlock(LHSBlock);
811 EmitBranchOnBoolExpr(CondOp->getLHS(), TrueBlock, FalseBlock);
812 cond.end(*this);
813
814 cond.begin(*this);
815 EmitBlock(RHSBlock);
816 EmitBranchOnBoolExpr(CondOp->getRHS(), TrueBlock, FalseBlock);
817 cond.end(*this);
818
819 return;
820 }
821
822 // Emit the code with the fully general case.
823 llvm::Value *CondV = EvaluateExprAsBool(Cond);
824 Builder.CreateCondBr(CondV, TrueBlock, FalseBlock);
825 }
826
827 /// ErrorUnsupported - Print out an error that codegen doesn't support the
828 /// specified stmt yet.
ErrorUnsupported(const Stmt * S,const char * Type,bool OmitOnError)829 void CodeGenFunction::ErrorUnsupported(const Stmt *S, const char *Type,
830 bool OmitOnError) {
831 CGM.ErrorUnsupported(S, Type, OmitOnError);
832 }
833
834 /// emitNonZeroVLAInit - Emit the "zero" initialization of a
835 /// variable-length array whose elements have a non-zero bit-pattern.
836 ///
837 /// \param baseType the inner-most element type of the array
838 /// \param src - a char* pointing to the bit-pattern for a single
839 /// base element of the array
840 /// \param sizeInChars - the total size of the VLA, in chars
emitNonZeroVLAInit(CodeGenFunction & CGF,QualType baseType,llvm::Value * dest,llvm::Value * src,llvm::Value * sizeInChars)841 static void emitNonZeroVLAInit(CodeGenFunction &CGF, QualType baseType,
842 llvm::Value *dest, llvm::Value *src,
843 llvm::Value *sizeInChars) {
844 std::pair<CharUnits,CharUnits> baseSizeAndAlign
845 = CGF.getContext().getTypeInfoInChars(baseType);
846
847 CGBuilderTy &Builder = CGF.Builder;
848
849 llvm::Value *baseSizeInChars
850 = llvm::ConstantInt::get(CGF.IntPtrTy, baseSizeAndAlign.first.getQuantity());
851
852 llvm::Type *i8p = Builder.getInt8PtrTy();
853
854 llvm::Value *begin = Builder.CreateBitCast(dest, i8p, "vla.begin");
855 llvm::Value *end = Builder.CreateInBoundsGEP(dest, sizeInChars, "vla.end");
856
857 llvm::BasicBlock *originBB = CGF.Builder.GetInsertBlock();
858 llvm::BasicBlock *loopBB = CGF.createBasicBlock("vla-init.loop");
859 llvm::BasicBlock *contBB = CGF.createBasicBlock("vla-init.cont");
860
861 // Make a loop over the VLA. C99 guarantees that the VLA element
862 // count must be nonzero.
863 CGF.EmitBlock(loopBB);
864
865 llvm::PHINode *cur = Builder.CreatePHI(i8p, 2, "vla.cur");
866 cur->addIncoming(begin, originBB);
867
868 // memcpy the individual element bit-pattern.
869 Builder.CreateMemCpy(cur, src, baseSizeInChars,
870 baseSizeAndAlign.second.getQuantity(),
871 /*volatile*/ false);
872
873 // Go to the next element.
874 llvm::Value *next = Builder.CreateConstInBoundsGEP1_32(cur, 1, "vla.next");
875
876 // Leave if that's the end of the VLA.
877 llvm::Value *done = Builder.CreateICmpEQ(next, end, "vla-init.isdone");
878 Builder.CreateCondBr(done, contBB, loopBB);
879 cur->addIncoming(next, loopBB);
880
881 CGF.EmitBlock(contBB);
882 }
883
884 void
EmitNullInitialization(llvm::Value * DestPtr,QualType Ty)885 CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) {
886 // Ignore empty classes in C++.
887 if (getLangOpts().CPlusPlus) {
888 if (const RecordType *RT = Ty->getAs<RecordType>()) {
889 if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty())
890 return;
891 }
892 }
893
894 // Cast the dest ptr to the appropriate i8 pointer type.
895 unsigned DestAS =
896 cast<llvm::PointerType>(DestPtr->getType())->getAddressSpace();
897 llvm::Type *BP = Builder.getInt8PtrTy(DestAS);
898 if (DestPtr->getType() != BP)
899 DestPtr = Builder.CreateBitCast(DestPtr, BP);
900
901 // Get size and alignment info for this aggregate.
902 std::pair<CharUnits, CharUnits> TypeInfo =
903 getContext().getTypeInfoInChars(Ty);
904 CharUnits Size = TypeInfo.first;
905 CharUnits Align = TypeInfo.second;
906
907 llvm::Value *SizeVal;
908 const VariableArrayType *vla;
909
910 // Don't bother emitting a zero-byte memset.
911 if (Size.isZero()) {
912 // But note that getTypeInfo returns 0 for a VLA.
913 if (const VariableArrayType *vlaType =
914 dyn_cast_or_null<VariableArrayType>(
915 getContext().getAsArrayType(Ty))) {
916 QualType eltType;
917 llvm::Value *numElts;
918 llvm::tie(numElts, eltType) = getVLASize(vlaType);
919
920 SizeVal = numElts;
921 CharUnits eltSize = getContext().getTypeSizeInChars(eltType);
922 if (!eltSize.isOne())
923 SizeVal = Builder.CreateNUWMul(SizeVal, CGM.getSize(eltSize));
924 vla = vlaType;
925 } else {
926 return;
927 }
928 } else {
929 SizeVal = CGM.getSize(Size);
930 vla = 0;
931 }
932
933 // If the type contains a pointer to data member we can't memset it to zero.
934 // Instead, create a null constant and copy it to the destination.
935 // TODO: there are other patterns besides zero that we can usefully memset,
936 // like -1, which happens to be the pattern used by member-pointers.
937 if (!CGM.getTypes().isZeroInitializable(Ty)) {
938 // For a VLA, emit a single element, then splat that over the VLA.
939 if (vla) Ty = getContext().getBaseElementType(vla);
940
941 llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty);
942
943 llvm::GlobalVariable *NullVariable =
944 new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(),
945 /*isConstant=*/true,
946 llvm::GlobalVariable::PrivateLinkage,
947 NullConstant, Twine());
948 llvm::Value *SrcPtr =
949 Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy());
950
951 if (vla) return emitNonZeroVLAInit(*this, Ty, DestPtr, SrcPtr, SizeVal);
952
953 // Get and call the appropriate llvm.memcpy overload.
954 Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, Align.getQuantity(), false);
955 return;
956 }
957
958 // Otherwise, just memset the whole thing to zero. This is legal
959 // because in LLVM, all default initializers (other than the ones we just
960 // handled above) are guaranteed to have a bit pattern of all zeros.
961 Builder.CreateMemSet(DestPtr, Builder.getInt8(0), SizeVal,
962 Align.getQuantity(), false);
963 }
964
GetAddrOfLabel(const LabelDecl * L)965 llvm::BlockAddress *CodeGenFunction::GetAddrOfLabel(const LabelDecl *L) {
966 // Make sure that there is a block for the indirect goto.
967 if (IndirectBranch == 0)
968 GetIndirectGotoBlock();
969
970 llvm::BasicBlock *BB = getJumpDestForLabel(L).getBlock();
971
972 // Make sure the indirect branch includes all of the address-taken blocks.
973 IndirectBranch->addDestination(BB);
974 return llvm::BlockAddress::get(CurFn, BB);
975 }
976
GetIndirectGotoBlock()977 llvm::BasicBlock *CodeGenFunction::GetIndirectGotoBlock() {
978 // If we already made the indirect branch for indirect goto, return its block.
979 if (IndirectBranch) return IndirectBranch->getParent();
980
981 CGBuilderTy TmpBuilder(createBasicBlock("indirectgoto"));
982
983 // Create the PHI node that indirect gotos will add entries to.
984 llvm::Value *DestVal = TmpBuilder.CreatePHI(Int8PtrTy, 0,
985 "indirect.goto.dest");
986
987 // Create the indirect branch instruction.
988 IndirectBranch = TmpBuilder.CreateIndirectBr(DestVal);
989 return IndirectBranch->getParent();
990 }
991
992 /// Computes the length of an array in elements, as well as the base
993 /// element type and a properly-typed first element pointer.
emitArrayLength(const ArrayType * origArrayType,QualType & baseType,llvm::Value * & addr)994 llvm::Value *CodeGenFunction::emitArrayLength(const ArrayType *origArrayType,
995 QualType &baseType,
996 llvm::Value *&addr) {
997 const ArrayType *arrayType = origArrayType;
998
999 // If it's a VLA, we have to load the stored size. Note that
1000 // this is the size of the VLA in bytes, not its size in elements.
1001 llvm::Value *numVLAElements = 0;
1002 if (isa<VariableArrayType>(arrayType)) {
1003 numVLAElements = getVLASize(cast<VariableArrayType>(arrayType)).first;
1004
1005 // Walk into all VLAs. This doesn't require changes to addr,
1006 // which has type T* where T is the first non-VLA element type.
1007 do {
1008 QualType elementType = arrayType->getElementType();
1009 arrayType = getContext().getAsArrayType(elementType);
1010
1011 // If we only have VLA components, 'addr' requires no adjustment.
1012 if (!arrayType) {
1013 baseType = elementType;
1014 return numVLAElements;
1015 }
1016 } while (isa<VariableArrayType>(arrayType));
1017
1018 // We get out here only if we find a constant array type
1019 // inside the VLA.
1020 }
1021
1022 // We have some number of constant-length arrays, so addr should
1023 // have LLVM type [M x [N x [...]]]*. Build a GEP that walks
1024 // down to the first element of addr.
1025 SmallVector<llvm::Value*, 8> gepIndices;
1026
1027 // GEP down to the array type.
1028 llvm::ConstantInt *zero = Builder.getInt32(0);
1029 gepIndices.push_back(zero);
1030
1031 uint64_t countFromCLAs = 1;
1032 QualType eltType;
1033
1034 llvm::ArrayType *llvmArrayType =
1035 dyn_cast<llvm::ArrayType>(
1036 cast<llvm::PointerType>(addr->getType())->getElementType());
1037 while (llvmArrayType) {
1038 assert(isa<ConstantArrayType>(arrayType));
1039 assert(cast<ConstantArrayType>(arrayType)->getSize().getZExtValue()
1040 == llvmArrayType->getNumElements());
1041
1042 gepIndices.push_back(zero);
1043 countFromCLAs *= llvmArrayType->getNumElements();
1044 eltType = arrayType->getElementType();
1045
1046 llvmArrayType =
1047 dyn_cast<llvm::ArrayType>(llvmArrayType->getElementType());
1048 arrayType = getContext().getAsArrayType(arrayType->getElementType());
1049 assert((!llvmArrayType || arrayType) &&
1050 "LLVM and Clang types are out-of-synch");
1051 }
1052
1053 if (arrayType) {
1054 // From this point onwards, the Clang array type has been emitted
1055 // as some other type (probably a packed struct). Compute the array
1056 // size, and just emit the 'begin' expression as a bitcast.
1057 while (arrayType) {
1058 countFromCLAs *=
1059 cast<ConstantArrayType>(arrayType)->getSize().getZExtValue();
1060 eltType = arrayType->getElementType();
1061 arrayType = getContext().getAsArrayType(eltType);
1062 }
1063
1064 unsigned AddressSpace = addr->getType()->getPointerAddressSpace();
1065 llvm::Type *BaseType = ConvertType(eltType)->getPointerTo(AddressSpace);
1066 addr = Builder.CreateBitCast(addr, BaseType, "array.begin");
1067 } else {
1068 // Create the actual GEP.
1069 addr = Builder.CreateInBoundsGEP(addr, gepIndices, "array.begin");
1070 }
1071
1072 baseType = eltType;
1073
1074 llvm::Value *numElements
1075 = llvm::ConstantInt::get(SizeTy, countFromCLAs);
1076
1077 // If we had any VLA dimensions, factor them in.
1078 if (numVLAElements)
1079 numElements = Builder.CreateNUWMul(numVLAElements, numElements);
1080
1081 return numElements;
1082 }
1083
1084 std::pair<llvm::Value*, QualType>
getVLASize(QualType type)1085 CodeGenFunction::getVLASize(QualType type) {
1086 const VariableArrayType *vla = getContext().getAsVariableArrayType(type);
1087 assert(vla && "type was not a variable array type!");
1088 return getVLASize(vla);
1089 }
1090
1091 std::pair<llvm::Value*, QualType>
getVLASize(const VariableArrayType * type)1092 CodeGenFunction::getVLASize(const VariableArrayType *type) {
1093 // The number of elements so far; always size_t.
1094 llvm::Value *numElements = 0;
1095
1096 QualType elementType;
1097 do {
1098 elementType = type->getElementType();
1099 llvm::Value *vlaSize = VLASizeMap[type->getSizeExpr()];
1100 assert(vlaSize && "no size for VLA!");
1101 assert(vlaSize->getType() == SizeTy);
1102
1103 if (!numElements) {
1104 numElements = vlaSize;
1105 } else {
1106 // It's undefined behavior if this wraps around, so mark it that way.
1107 // FIXME: Teach -fcatch-undefined-behavior to trap this.
1108 numElements = Builder.CreateNUWMul(numElements, vlaSize);
1109 }
1110 } while ((type = getContext().getAsVariableArrayType(elementType)));
1111
1112 return std::pair<llvm::Value*,QualType>(numElements, elementType);
1113 }
1114
EmitVariablyModifiedType(QualType type)1115 void CodeGenFunction::EmitVariablyModifiedType(QualType type) {
1116 assert(type->isVariablyModifiedType() &&
1117 "Must pass variably modified type to EmitVLASizes!");
1118
1119 EnsureInsertPoint();
1120
1121 // We're going to walk down into the type and look for VLA
1122 // expressions.
1123 do {
1124 assert(type->isVariablyModifiedType());
1125
1126 const Type *ty = type.getTypePtr();
1127 switch (ty->getTypeClass()) {
1128
1129 #define TYPE(Class, Base)
1130 #define ABSTRACT_TYPE(Class, Base)
1131 #define NON_CANONICAL_TYPE(Class, Base)
1132 #define DEPENDENT_TYPE(Class, Base) case Type::Class:
1133 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base)
1134 #include "clang/AST/TypeNodes.def"
1135 llvm_unreachable("unexpected dependent type!");
1136
1137 // These types are never variably-modified.
1138 case Type::Builtin:
1139 case Type::Complex:
1140 case Type::Vector:
1141 case Type::ExtVector:
1142 case Type::Record:
1143 case Type::Enum:
1144 case Type::Elaborated:
1145 case Type::TemplateSpecialization:
1146 case Type::ObjCObject:
1147 case Type::ObjCInterface:
1148 case Type::ObjCObjectPointer:
1149 llvm_unreachable("type class is never variably-modified!");
1150
1151 case Type::Pointer:
1152 type = cast<PointerType>(ty)->getPointeeType();
1153 break;
1154
1155 case Type::BlockPointer:
1156 type = cast<BlockPointerType>(ty)->getPointeeType();
1157 break;
1158
1159 case Type::LValueReference:
1160 case Type::RValueReference:
1161 type = cast<ReferenceType>(ty)->getPointeeType();
1162 break;
1163
1164 case Type::MemberPointer:
1165 type = cast<MemberPointerType>(ty)->getPointeeType();
1166 break;
1167
1168 case Type::ConstantArray:
1169 case Type::IncompleteArray:
1170 // Losing element qualification here is fine.
1171 type = cast<ArrayType>(ty)->getElementType();
1172 break;
1173
1174 case Type::VariableArray: {
1175 // Losing element qualification here is fine.
1176 const VariableArrayType *vat = cast<VariableArrayType>(ty);
1177
1178 // Unknown size indication requires no size computation.
1179 // Otherwise, evaluate and record it.
1180 if (const Expr *size = vat->getSizeExpr()) {
1181 // It's possible that we might have emitted this already,
1182 // e.g. with a typedef and a pointer to it.
1183 llvm::Value *&entry = VLASizeMap[size];
1184 if (!entry) {
1185 llvm::Value *Size = EmitScalarExpr(size);
1186
1187 // C11 6.7.6.2p5:
1188 // If the size is an expression that is not an integer constant
1189 // expression [...] each time it is evaluated it shall have a value
1190 // greater than zero.
1191 if (SanOpts->VLABound &&
1192 size->getType()->isSignedIntegerType()) {
1193 llvm::Value *Zero = llvm::Constant::getNullValue(Size->getType());
1194 llvm::Constant *StaticArgs[] = {
1195 EmitCheckSourceLocation(size->getLocStart()),
1196 EmitCheckTypeDescriptor(size->getType())
1197 };
1198 EmitCheck(Builder.CreateICmpSGT(Size, Zero),
1199 "vla_bound_not_positive", StaticArgs, Size,
1200 CRK_Recoverable);
1201 }
1202
1203 // Always zexting here would be wrong if it weren't
1204 // undefined behavior to have a negative bound.
1205 entry = Builder.CreateIntCast(Size, SizeTy, /*signed*/ false);
1206 }
1207 }
1208 type = vat->getElementType();
1209 break;
1210 }
1211
1212 case Type::FunctionProto:
1213 case Type::FunctionNoProto:
1214 type = cast<FunctionType>(ty)->getResultType();
1215 break;
1216
1217 case Type::Paren:
1218 case Type::TypeOf:
1219 case Type::UnaryTransform:
1220 case Type::Attributed:
1221 case Type::SubstTemplateTypeParm:
1222 // Keep walking after single level desugaring.
1223 type = type.getSingleStepDesugaredType(getContext());
1224 break;
1225
1226 case Type::Typedef:
1227 case Type::Decltype:
1228 case Type::Auto:
1229 // Stop walking: nothing to do.
1230 return;
1231
1232 case Type::TypeOfExpr:
1233 // Stop walking: emit typeof expression.
1234 EmitIgnoredExpr(cast<TypeOfExprType>(ty)->getUnderlyingExpr());
1235 return;
1236
1237 case Type::Atomic:
1238 type = cast<AtomicType>(ty)->getValueType();
1239 break;
1240 }
1241 } while (type->isVariablyModifiedType());
1242 }
1243
EmitVAListRef(const Expr * E)1244 llvm::Value* CodeGenFunction::EmitVAListRef(const Expr* E) {
1245 if (getContext().getBuiltinVaListType()->isArrayType())
1246 return EmitScalarExpr(E);
1247 return EmitLValue(E).getAddress();
1248 }
1249
EmitDeclRefExprDbgValue(const DeclRefExpr * E,llvm::Constant * Init)1250 void CodeGenFunction::EmitDeclRefExprDbgValue(const DeclRefExpr *E,
1251 llvm::Constant *Init) {
1252 assert (Init && "Invalid DeclRefExpr initializer!");
1253 if (CGDebugInfo *Dbg = getDebugInfo())
1254 if (CGM.getCodeGenOpts().getDebugInfo() >= CodeGenOptions::LimitedDebugInfo)
1255 Dbg->EmitGlobalVariable(E->getDecl(), Init);
1256 }
1257
1258 CodeGenFunction::PeepholeProtection
protectFromPeepholes(RValue rvalue)1259 CodeGenFunction::protectFromPeepholes(RValue rvalue) {
1260 // At the moment, the only aggressive peephole we do in IR gen
1261 // is trunc(zext) folding, but if we add more, we can easily
1262 // extend this protection.
1263
1264 if (!rvalue.isScalar()) return PeepholeProtection();
1265 llvm::Value *value = rvalue.getScalarVal();
1266 if (!isa<llvm::ZExtInst>(value)) return PeepholeProtection();
1267
1268 // Just make an extra bitcast.
1269 assert(HaveInsertPoint());
1270 llvm::Instruction *inst = new llvm::BitCastInst(value, value->getType(), "",
1271 Builder.GetInsertBlock());
1272
1273 PeepholeProtection protection;
1274 protection.Inst = inst;
1275 return protection;
1276 }
1277
unprotectFromPeepholes(PeepholeProtection protection)1278 void CodeGenFunction::unprotectFromPeepholes(PeepholeProtection protection) {
1279 if (!protection.Inst) return;
1280
1281 // In theory, we could try to duplicate the peepholes now, but whatever.
1282 protection.Inst->eraseFromParent();
1283 }
1284
EmitAnnotationCall(llvm::Value * AnnotationFn,llvm::Value * AnnotatedVal,StringRef AnnotationStr,SourceLocation Location)1285 llvm::Value *CodeGenFunction::EmitAnnotationCall(llvm::Value *AnnotationFn,
1286 llvm::Value *AnnotatedVal,
1287 StringRef AnnotationStr,
1288 SourceLocation Location) {
1289 llvm::Value *Args[4] = {
1290 AnnotatedVal,
1291 Builder.CreateBitCast(CGM.EmitAnnotationString(AnnotationStr), Int8PtrTy),
1292 Builder.CreateBitCast(CGM.EmitAnnotationUnit(Location), Int8PtrTy),
1293 CGM.EmitAnnotationLineNo(Location)
1294 };
1295 return Builder.CreateCall(AnnotationFn, Args);
1296 }
1297
EmitVarAnnotations(const VarDecl * D,llvm::Value * V)1298 void CodeGenFunction::EmitVarAnnotations(const VarDecl *D, llvm::Value *V) {
1299 assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute");
1300 // FIXME We create a new bitcast for every annotation because that's what
1301 // llvm-gcc was doing.
1302 for (specific_attr_iterator<AnnotateAttr>
1303 ai = D->specific_attr_begin<AnnotateAttr>(),
1304 ae = D->specific_attr_end<AnnotateAttr>(); ai != ae; ++ai)
1305 EmitAnnotationCall(CGM.getIntrinsic(llvm::Intrinsic::var_annotation),
1306 Builder.CreateBitCast(V, CGM.Int8PtrTy, V->getName()),
1307 (*ai)->getAnnotation(), D->getLocation());
1308 }
1309
EmitFieldAnnotations(const FieldDecl * D,llvm::Value * V)1310 llvm::Value *CodeGenFunction::EmitFieldAnnotations(const FieldDecl *D,
1311 llvm::Value *V) {
1312 assert(D->hasAttr<AnnotateAttr>() && "no annotate attribute");
1313 llvm::Type *VTy = V->getType();
1314 llvm::Value *F = CGM.getIntrinsic(llvm::Intrinsic::ptr_annotation,
1315 CGM.Int8PtrTy);
1316
1317 for (specific_attr_iterator<AnnotateAttr>
1318 ai = D->specific_attr_begin<AnnotateAttr>(),
1319 ae = D->specific_attr_end<AnnotateAttr>(); ai != ae; ++ai) {
1320 // FIXME Always emit the cast inst so we can differentiate between
1321 // annotation on the first field of a struct and annotation on the struct
1322 // itself.
1323 if (VTy != CGM.Int8PtrTy)
1324 V = Builder.Insert(new llvm::BitCastInst(V, CGM.Int8PtrTy));
1325 V = EmitAnnotationCall(F, V, (*ai)->getAnnotation(), D->getLocation());
1326 V = Builder.CreateBitCast(V, VTy);
1327 }
1328
1329 return V;
1330 }
1331