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1 //===--- CGStmt.cpp - Emit LLVM Code from Statements ----------------------===//
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 Stmt nodes as LLVM code.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "CodeGenFunction.h"
15 #include "CGDebugInfo.h"
16 #include "CodeGenModule.h"
17 #include "TargetInfo.h"
18 #include "clang/AST/StmtVisitor.h"
19 #include "clang/Basic/Builtins.h"
20 #include "clang/Basic/PrettyStackTrace.h"
21 #include "clang/Basic/TargetInfo.h"
22 #include "clang/Sema/LoopHint.h"
23 #include "clang/Sema/SemaDiagnostic.h"
24 #include "llvm/ADT/StringExtras.h"
25 #include "llvm/IR/CallSite.h"
26 #include "llvm/IR/DataLayout.h"
27 #include "llvm/IR/InlineAsm.h"
28 #include "llvm/IR/Intrinsics.h"
29 #include "llvm/IR/MDBuilder.h"
30 
31 using namespace clang;
32 using namespace CodeGen;
33 
34 //===----------------------------------------------------------------------===//
35 //                              Statement Emission
36 //===----------------------------------------------------------------------===//
37 
EmitStopPoint(const Stmt * S)38 void CodeGenFunction::EmitStopPoint(const Stmt *S) {
39   if (CGDebugInfo *DI = getDebugInfo()) {
40     SourceLocation Loc;
41     Loc = S->getLocStart();
42     DI->EmitLocation(Builder, Loc);
43 
44     LastStopPoint = Loc;
45   }
46 }
47 
EmitStmt(const Stmt * S)48 void CodeGenFunction::EmitStmt(const Stmt *S) {
49   assert(S && "Null statement?");
50   PGO.setCurrentStmt(S);
51 
52   // These statements have their own debug info handling.
53   if (EmitSimpleStmt(S))
54     return;
55 
56   // Check if we are generating unreachable code.
57   if (!HaveInsertPoint()) {
58     // If so, and the statement doesn't contain a label, then we do not need to
59     // generate actual code. This is safe because (1) the current point is
60     // unreachable, so we don't need to execute the code, and (2) we've already
61     // handled the statements which update internal data structures (like the
62     // local variable map) which could be used by subsequent statements.
63     if (!ContainsLabel(S)) {
64       // Verify that any decl statements were handled as simple, they may be in
65       // scope of subsequent reachable statements.
66       assert(!isa<DeclStmt>(*S) && "Unexpected DeclStmt!");
67       return;
68     }
69 
70     // Otherwise, make a new block to hold the code.
71     EnsureInsertPoint();
72   }
73 
74   // Generate a stoppoint if we are emitting debug info.
75   EmitStopPoint(S);
76 
77   switch (S->getStmtClass()) {
78   case Stmt::NoStmtClass:
79   case Stmt::CXXCatchStmtClass:
80   case Stmt::SEHExceptStmtClass:
81   case Stmt::SEHFinallyStmtClass:
82   case Stmt::MSDependentExistsStmtClass:
83     llvm_unreachable("invalid statement class to emit generically");
84   case Stmt::NullStmtClass:
85   case Stmt::CompoundStmtClass:
86   case Stmt::DeclStmtClass:
87   case Stmt::LabelStmtClass:
88   case Stmt::AttributedStmtClass:
89   case Stmt::GotoStmtClass:
90   case Stmt::BreakStmtClass:
91   case Stmt::ContinueStmtClass:
92   case Stmt::DefaultStmtClass:
93   case Stmt::CaseStmtClass:
94   case Stmt::SEHLeaveStmtClass:
95     llvm_unreachable("should have emitted these statements as simple");
96 
97 #define STMT(Type, Base)
98 #define ABSTRACT_STMT(Op)
99 #define EXPR(Type, Base) \
100   case Stmt::Type##Class:
101 #include "clang/AST/StmtNodes.inc"
102   {
103     // Remember the block we came in on.
104     llvm::BasicBlock *incoming = Builder.GetInsertBlock();
105     assert(incoming && "expression emission must have an insertion point");
106 
107     EmitIgnoredExpr(cast<Expr>(S));
108 
109     llvm::BasicBlock *outgoing = Builder.GetInsertBlock();
110     assert(outgoing && "expression emission cleared block!");
111 
112     // The expression emitters assume (reasonably!) that the insertion
113     // point is always set.  To maintain that, the call-emission code
114     // for noreturn functions has to enter a new block with no
115     // predecessors.  We want to kill that block and mark the current
116     // insertion point unreachable in the common case of a call like
117     // "exit();".  Since expression emission doesn't otherwise create
118     // blocks with no predecessors, we can just test for that.
119     // However, we must be careful not to do this to our incoming
120     // block, because *statement* emission does sometimes create
121     // reachable blocks which will have no predecessors until later in
122     // the function.  This occurs with, e.g., labels that are not
123     // reachable by fallthrough.
124     if (incoming != outgoing && outgoing->use_empty()) {
125       outgoing->eraseFromParent();
126       Builder.ClearInsertionPoint();
127     }
128     break;
129   }
130 
131   case Stmt::IndirectGotoStmtClass:
132     EmitIndirectGotoStmt(cast<IndirectGotoStmt>(*S)); break;
133 
134   case Stmt::IfStmtClass:       EmitIfStmt(cast<IfStmt>(*S));             break;
135   case Stmt::WhileStmtClass:    EmitWhileStmt(cast<WhileStmt>(*S));       break;
136   case Stmt::DoStmtClass:       EmitDoStmt(cast<DoStmt>(*S));             break;
137   case Stmt::ForStmtClass:      EmitForStmt(cast<ForStmt>(*S));           break;
138 
139   case Stmt::ReturnStmtClass:   EmitReturnStmt(cast<ReturnStmt>(*S));     break;
140 
141   case Stmt::SwitchStmtClass:   EmitSwitchStmt(cast<SwitchStmt>(*S));     break;
142   case Stmt::GCCAsmStmtClass:   // Intentional fall-through.
143   case Stmt::MSAsmStmtClass:    EmitAsmStmt(cast<AsmStmt>(*S));           break;
144   case Stmt::CoroutineBodyStmtClass:
145   case Stmt::CoreturnStmtClass:
146     CGM.ErrorUnsupported(S, "coroutine");
147     break;
148   case Stmt::CapturedStmtClass: {
149     const CapturedStmt *CS = cast<CapturedStmt>(S);
150     EmitCapturedStmt(*CS, CS->getCapturedRegionKind());
151     }
152     break;
153   case Stmt::ObjCAtTryStmtClass:
154     EmitObjCAtTryStmt(cast<ObjCAtTryStmt>(*S));
155     break;
156   case Stmt::ObjCAtCatchStmtClass:
157     llvm_unreachable(
158                     "@catch statements should be handled by EmitObjCAtTryStmt");
159   case Stmt::ObjCAtFinallyStmtClass:
160     llvm_unreachable(
161                   "@finally statements should be handled by EmitObjCAtTryStmt");
162   case Stmt::ObjCAtThrowStmtClass:
163     EmitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(*S));
164     break;
165   case Stmt::ObjCAtSynchronizedStmtClass:
166     EmitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(*S));
167     break;
168   case Stmt::ObjCForCollectionStmtClass:
169     EmitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(*S));
170     break;
171   case Stmt::ObjCAutoreleasePoolStmtClass:
172     EmitObjCAutoreleasePoolStmt(cast<ObjCAutoreleasePoolStmt>(*S));
173     break;
174 
175   case Stmt::CXXTryStmtClass:
176     EmitCXXTryStmt(cast<CXXTryStmt>(*S));
177     break;
178   case Stmt::CXXForRangeStmtClass:
179     EmitCXXForRangeStmt(cast<CXXForRangeStmt>(*S));
180     break;
181   case Stmt::SEHTryStmtClass:
182     EmitSEHTryStmt(cast<SEHTryStmt>(*S));
183     break;
184   case Stmt::OMPParallelDirectiveClass:
185     EmitOMPParallelDirective(cast<OMPParallelDirective>(*S));
186     break;
187   case Stmt::OMPSimdDirectiveClass:
188     EmitOMPSimdDirective(cast<OMPSimdDirective>(*S));
189     break;
190   case Stmt::OMPForDirectiveClass:
191     EmitOMPForDirective(cast<OMPForDirective>(*S));
192     break;
193   case Stmt::OMPForSimdDirectiveClass:
194     EmitOMPForSimdDirective(cast<OMPForSimdDirective>(*S));
195     break;
196   case Stmt::OMPSectionsDirectiveClass:
197     EmitOMPSectionsDirective(cast<OMPSectionsDirective>(*S));
198     break;
199   case Stmt::OMPSectionDirectiveClass:
200     EmitOMPSectionDirective(cast<OMPSectionDirective>(*S));
201     break;
202   case Stmt::OMPSingleDirectiveClass:
203     EmitOMPSingleDirective(cast<OMPSingleDirective>(*S));
204     break;
205   case Stmt::OMPMasterDirectiveClass:
206     EmitOMPMasterDirective(cast<OMPMasterDirective>(*S));
207     break;
208   case Stmt::OMPCriticalDirectiveClass:
209     EmitOMPCriticalDirective(cast<OMPCriticalDirective>(*S));
210     break;
211   case Stmt::OMPParallelForDirectiveClass:
212     EmitOMPParallelForDirective(cast<OMPParallelForDirective>(*S));
213     break;
214   case Stmt::OMPParallelForSimdDirectiveClass:
215     EmitOMPParallelForSimdDirective(cast<OMPParallelForSimdDirective>(*S));
216     break;
217   case Stmt::OMPParallelSectionsDirectiveClass:
218     EmitOMPParallelSectionsDirective(cast<OMPParallelSectionsDirective>(*S));
219     break;
220   case Stmt::OMPTaskDirectiveClass:
221     EmitOMPTaskDirective(cast<OMPTaskDirective>(*S));
222     break;
223   case Stmt::OMPTaskyieldDirectiveClass:
224     EmitOMPTaskyieldDirective(cast<OMPTaskyieldDirective>(*S));
225     break;
226   case Stmt::OMPBarrierDirectiveClass:
227     EmitOMPBarrierDirective(cast<OMPBarrierDirective>(*S));
228     break;
229   case Stmt::OMPTaskwaitDirectiveClass:
230     EmitOMPTaskwaitDirective(cast<OMPTaskwaitDirective>(*S));
231     break;
232   case Stmt::OMPTaskgroupDirectiveClass:
233     EmitOMPTaskgroupDirective(cast<OMPTaskgroupDirective>(*S));
234     break;
235   case Stmt::OMPFlushDirectiveClass:
236     EmitOMPFlushDirective(cast<OMPFlushDirective>(*S));
237     break;
238   case Stmt::OMPOrderedDirectiveClass:
239     EmitOMPOrderedDirective(cast<OMPOrderedDirective>(*S));
240     break;
241   case Stmt::OMPAtomicDirectiveClass:
242     EmitOMPAtomicDirective(cast<OMPAtomicDirective>(*S));
243     break;
244   case Stmt::OMPTargetDirectiveClass:
245     EmitOMPTargetDirective(cast<OMPTargetDirective>(*S));
246     break;
247   case Stmt::OMPTeamsDirectiveClass:
248     EmitOMPTeamsDirective(cast<OMPTeamsDirective>(*S));
249     break;
250   case Stmt::OMPCancellationPointDirectiveClass:
251     EmitOMPCancellationPointDirective(cast<OMPCancellationPointDirective>(*S));
252     break;
253   case Stmt::OMPCancelDirectiveClass:
254     EmitOMPCancelDirective(cast<OMPCancelDirective>(*S));
255     break;
256   case Stmt::OMPTargetDataDirectiveClass:
257     EmitOMPTargetDataDirective(cast<OMPTargetDataDirective>(*S));
258     break;
259   case Stmt::OMPTargetEnterDataDirectiveClass:
260     EmitOMPTargetEnterDataDirective(cast<OMPTargetEnterDataDirective>(*S));
261     break;
262   case Stmt::OMPTargetExitDataDirectiveClass:
263     EmitOMPTargetExitDataDirective(cast<OMPTargetExitDataDirective>(*S));
264     break;
265   case Stmt::OMPTargetParallelDirectiveClass:
266     EmitOMPTargetParallelDirective(cast<OMPTargetParallelDirective>(*S));
267     break;
268   case Stmt::OMPTargetParallelForDirectiveClass:
269     EmitOMPTargetParallelForDirective(cast<OMPTargetParallelForDirective>(*S));
270     break;
271   case Stmt::OMPTaskLoopDirectiveClass:
272     EmitOMPTaskLoopDirective(cast<OMPTaskLoopDirective>(*S));
273     break;
274   case Stmt::OMPTaskLoopSimdDirectiveClass:
275     EmitOMPTaskLoopSimdDirective(cast<OMPTaskLoopSimdDirective>(*S));
276     break;
277   case Stmt::OMPDistributeDirectiveClass:
278     EmitOMPDistributeDirective(cast<OMPDistributeDirective>(*S));
279     break;
280   case Stmt::OMPTargetUpdateDirectiveClass:
281     EmitOMPTargetUpdateDirective(cast<OMPTargetUpdateDirective>(*S));
282     break;
283   case Stmt::OMPDistributeParallelForDirectiveClass:
284     EmitOMPDistributeParallelForDirective(
285         cast<OMPDistributeParallelForDirective>(*S));
286     break;
287   case Stmt::OMPDistributeParallelForSimdDirectiveClass:
288     EmitOMPDistributeParallelForSimdDirective(
289         cast<OMPDistributeParallelForSimdDirective>(*S));
290     break;
291   case Stmt::OMPDistributeSimdDirectiveClass:
292     EmitOMPDistributeSimdDirective(cast<OMPDistributeSimdDirective>(*S));
293     break;
294   case Stmt::OMPTargetParallelForSimdDirectiveClass:
295     EmitOMPTargetParallelForSimdDirective(
296         cast<OMPTargetParallelForSimdDirective>(*S));
297     break;
298   }
299 }
300 
EmitSimpleStmt(const Stmt * S)301 bool CodeGenFunction::EmitSimpleStmt(const Stmt *S) {
302   switch (S->getStmtClass()) {
303   default: return false;
304   case Stmt::NullStmtClass: break;
305   case Stmt::CompoundStmtClass: EmitCompoundStmt(cast<CompoundStmt>(*S)); break;
306   case Stmt::DeclStmtClass:     EmitDeclStmt(cast<DeclStmt>(*S));         break;
307   case Stmt::LabelStmtClass:    EmitLabelStmt(cast<LabelStmt>(*S));       break;
308   case Stmt::AttributedStmtClass:
309                             EmitAttributedStmt(cast<AttributedStmt>(*S)); break;
310   case Stmt::GotoStmtClass:     EmitGotoStmt(cast<GotoStmt>(*S));         break;
311   case Stmt::BreakStmtClass:    EmitBreakStmt(cast<BreakStmt>(*S));       break;
312   case Stmt::ContinueStmtClass: EmitContinueStmt(cast<ContinueStmt>(*S)); break;
313   case Stmt::DefaultStmtClass:  EmitDefaultStmt(cast<DefaultStmt>(*S));   break;
314   case Stmt::CaseStmtClass:     EmitCaseStmt(cast<CaseStmt>(*S));         break;
315   case Stmt::SEHLeaveStmtClass: EmitSEHLeaveStmt(cast<SEHLeaveStmt>(*S)); break;
316   }
317 
318   return true;
319 }
320 
321 /// EmitCompoundStmt - Emit a compound statement {..} node.  If GetLast is true,
322 /// this captures the expression result of the last sub-statement and returns it
323 /// (for use by the statement expression extension).
EmitCompoundStmt(const CompoundStmt & S,bool GetLast,AggValueSlot AggSlot)324 Address CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast,
325                                           AggValueSlot AggSlot) {
326   PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),S.getLBracLoc(),
327                              "LLVM IR generation of compound statement ('{}')");
328 
329   // Keep track of the current cleanup stack depth, including debug scopes.
330   LexicalScope Scope(*this, S.getSourceRange());
331 
332   return EmitCompoundStmtWithoutScope(S, GetLast, AggSlot);
333 }
334 
335 Address
EmitCompoundStmtWithoutScope(const CompoundStmt & S,bool GetLast,AggValueSlot AggSlot)336 CodeGenFunction::EmitCompoundStmtWithoutScope(const CompoundStmt &S,
337                                               bool GetLast,
338                                               AggValueSlot AggSlot) {
339 
340   for (CompoundStmt::const_body_iterator I = S.body_begin(),
341        E = S.body_end()-GetLast; I != E; ++I)
342     EmitStmt(*I);
343 
344   Address RetAlloca = Address::invalid();
345   if (GetLast) {
346     // We have to special case labels here.  They are statements, but when put
347     // at the end of a statement expression, they yield the value of their
348     // subexpression.  Handle this by walking through all labels we encounter,
349     // emitting them before we evaluate the subexpr.
350     const Stmt *LastStmt = S.body_back();
351     while (const LabelStmt *LS = dyn_cast<LabelStmt>(LastStmt)) {
352       EmitLabel(LS->getDecl());
353       LastStmt = LS->getSubStmt();
354     }
355 
356     EnsureInsertPoint();
357 
358     QualType ExprTy = cast<Expr>(LastStmt)->getType();
359     if (hasAggregateEvaluationKind(ExprTy)) {
360       EmitAggExpr(cast<Expr>(LastStmt), AggSlot);
361     } else {
362       // We can't return an RValue here because there might be cleanups at
363       // the end of the StmtExpr.  Because of that, we have to emit the result
364       // here into a temporary alloca.
365       RetAlloca = CreateMemTemp(ExprTy);
366       EmitAnyExprToMem(cast<Expr>(LastStmt), RetAlloca, Qualifiers(),
367                        /*IsInit*/false);
368     }
369 
370   }
371 
372   return RetAlloca;
373 }
374 
SimplifyForwardingBlocks(llvm::BasicBlock * BB)375 void CodeGenFunction::SimplifyForwardingBlocks(llvm::BasicBlock *BB) {
376   llvm::BranchInst *BI = dyn_cast<llvm::BranchInst>(BB->getTerminator());
377 
378   // If there is a cleanup stack, then we it isn't worth trying to
379   // simplify this block (we would need to remove it from the scope map
380   // and cleanup entry).
381   if (!EHStack.empty())
382     return;
383 
384   // Can only simplify direct branches.
385   if (!BI || !BI->isUnconditional())
386     return;
387 
388   // Can only simplify empty blocks.
389   if (BI->getIterator() != BB->begin())
390     return;
391 
392   BB->replaceAllUsesWith(BI->getSuccessor(0));
393   BI->eraseFromParent();
394   BB->eraseFromParent();
395 }
396 
EmitBlock(llvm::BasicBlock * BB,bool IsFinished)397 void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) {
398   llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
399 
400   // Fall out of the current block (if necessary).
401   EmitBranch(BB);
402 
403   if (IsFinished && BB->use_empty()) {
404     delete BB;
405     return;
406   }
407 
408   // Place the block after the current block, if possible, or else at
409   // the end of the function.
410   if (CurBB && CurBB->getParent())
411     CurFn->getBasicBlockList().insertAfter(CurBB->getIterator(), BB);
412   else
413     CurFn->getBasicBlockList().push_back(BB);
414   Builder.SetInsertPoint(BB);
415 }
416 
EmitBranch(llvm::BasicBlock * Target)417 void CodeGenFunction::EmitBranch(llvm::BasicBlock *Target) {
418   // Emit a branch from the current block to the target one if this
419   // was a real block.  If this was just a fall-through block after a
420   // terminator, don't emit it.
421   llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
422 
423   if (!CurBB || CurBB->getTerminator()) {
424     // If there is no insert point or the previous block is already
425     // terminated, don't touch it.
426   } else {
427     // Otherwise, create a fall-through branch.
428     Builder.CreateBr(Target);
429   }
430 
431   Builder.ClearInsertionPoint();
432 }
433 
EmitBlockAfterUses(llvm::BasicBlock * block)434 void CodeGenFunction::EmitBlockAfterUses(llvm::BasicBlock *block) {
435   bool inserted = false;
436   for (llvm::User *u : block->users()) {
437     if (llvm::Instruction *insn = dyn_cast<llvm::Instruction>(u)) {
438       CurFn->getBasicBlockList().insertAfter(insn->getParent()->getIterator(),
439                                              block);
440       inserted = true;
441       break;
442     }
443   }
444 
445   if (!inserted)
446     CurFn->getBasicBlockList().push_back(block);
447 
448   Builder.SetInsertPoint(block);
449 }
450 
451 CodeGenFunction::JumpDest
getJumpDestForLabel(const LabelDecl * D)452 CodeGenFunction::getJumpDestForLabel(const LabelDecl *D) {
453   JumpDest &Dest = LabelMap[D];
454   if (Dest.isValid()) return Dest;
455 
456   // Create, but don't insert, the new block.
457   Dest = JumpDest(createBasicBlock(D->getName()),
458                   EHScopeStack::stable_iterator::invalid(),
459                   NextCleanupDestIndex++);
460   return Dest;
461 }
462 
EmitLabel(const LabelDecl * D)463 void CodeGenFunction::EmitLabel(const LabelDecl *D) {
464   // Add this label to the current lexical scope if we're within any
465   // normal cleanups.  Jumps "in" to this label --- when permitted by
466   // the language --- may need to be routed around such cleanups.
467   if (EHStack.hasNormalCleanups() && CurLexicalScope)
468     CurLexicalScope->addLabel(D);
469 
470   JumpDest &Dest = LabelMap[D];
471 
472   // If we didn't need a forward reference to this label, just go
473   // ahead and create a destination at the current scope.
474   if (!Dest.isValid()) {
475     Dest = getJumpDestInCurrentScope(D->getName());
476 
477   // Otherwise, we need to give this label a target depth and remove
478   // it from the branch-fixups list.
479   } else {
480     assert(!Dest.getScopeDepth().isValid() && "already emitted label!");
481     Dest.setScopeDepth(EHStack.stable_begin());
482     ResolveBranchFixups(Dest.getBlock());
483   }
484 
485   EmitBlock(Dest.getBlock());
486   incrementProfileCounter(D->getStmt());
487 }
488 
489 /// Change the cleanup scope of the labels in this lexical scope to
490 /// match the scope of the enclosing context.
rescopeLabels()491 void CodeGenFunction::LexicalScope::rescopeLabels() {
492   assert(!Labels.empty());
493   EHScopeStack::stable_iterator innermostScope
494     = CGF.EHStack.getInnermostNormalCleanup();
495 
496   // Change the scope depth of all the labels.
497   for (SmallVectorImpl<const LabelDecl*>::const_iterator
498          i = Labels.begin(), e = Labels.end(); i != e; ++i) {
499     assert(CGF.LabelMap.count(*i));
500     JumpDest &dest = CGF.LabelMap.find(*i)->second;
501     assert(dest.getScopeDepth().isValid());
502     assert(innermostScope.encloses(dest.getScopeDepth()));
503     dest.setScopeDepth(innermostScope);
504   }
505 
506   // Reparent the labels if the new scope also has cleanups.
507   if (innermostScope != EHScopeStack::stable_end() && ParentScope) {
508     ParentScope->Labels.append(Labels.begin(), Labels.end());
509   }
510 }
511 
512 
EmitLabelStmt(const LabelStmt & S)513 void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) {
514   EmitLabel(S.getDecl());
515   EmitStmt(S.getSubStmt());
516 }
517 
EmitAttributedStmt(const AttributedStmt & S)518 void CodeGenFunction::EmitAttributedStmt(const AttributedStmt &S) {
519   const Stmt *SubStmt = S.getSubStmt();
520   switch (SubStmt->getStmtClass()) {
521   case Stmt::DoStmtClass:
522     EmitDoStmt(cast<DoStmt>(*SubStmt), S.getAttrs());
523     break;
524   case Stmt::ForStmtClass:
525     EmitForStmt(cast<ForStmt>(*SubStmt), S.getAttrs());
526     break;
527   case Stmt::WhileStmtClass:
528     EmitWhileStmt(cast<WhileStmt>(*SubStmt), S.getAttrs());
529     break;
530   case Stmt::CXXForRangeStmtClass:
531     EmitCXXForRangeStmt(cast<CXXForRangeStmt>(*SubStmt), S.getAttrs());
532     break;
533   default:
534     EmitStmt(SubStmt);
535   }
536 }
537 
EmitGotoStmt(const GotoStmt & S)538 void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) {
539   // If this code is reachable then emit a stop point (if generating
540   // debug info). We have to do this ourselves because we are on the
541   // "simple" statement path.
542   if (HaveInsertPoint())
543     EmitStopPoint(&S);
544 
545   EmitBranchThroughCleanup(getJumpDestForLabel(S.getLabel()));
546 }
547 
548 
EmitIndirectGotoStmt(const IndirectGotoStmt & S)549 void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) {
550   if (const LabelDecl *Target = S.getConstantTarget()) {
551     EmitBranchThroughCleanup(getJumpDestForLabel(Target));
552     return;
553   }
554 
555   // Ensure that we have an i8* for our PHI node.
556   llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()),
557                                          Int8PtrTy, "addr");
558   llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
559 
560   // Get the basic block for the indirect goto.
561   llvm::BasicBlock *IndGotoBB = GetIndirectGotoBlock();
562 
563   // The first instruction in the block has to be the PHI for the switch dest,
564   // add an entry for this branch.
565   cast<llvm::PHINode>(IndGotoBB->begin())->addIncoming(V, CurBB);
566 
567   EmitBranch(IndGotoBB);
568 }
569 
EmitIfStmt(const IfStmt & S)570 void CodeGenFunction::EmitIfStmt(const IfStmt &S) {
571   // C99 6.8.4.1: The first substatement is executed if the expression compares
572   // unequal to 0.  The condition must be a scalar type.
573   LexicalScope ConditionScope(*this, S.getCond()->getSourceRange());
574 
575   if (S.getInit())
576     EmitStmt(S.getInit());
577 
578   if (S.getConditionVariable())
579     EmitAutoVarDecl(*S.getConditionVariable());
580 
581   // If the condition constant folds and can be elided, try to avoid emitting
582   // the condition and the dead arm of the if/else.
583   bool CondConstant;
584   if (ConstantFoldsToSimpleInteger(S.getCond(), CondConstant,
585                                    S.isConstexpr())) {
586     // Figure out which block (then or else) is executed.
587     const Stmt *Executed = S.getThen();
588     const Stmt *Skipped  = S.getElse();
589     if (!CondConstant)  // Condition false?
590       std::swap(Executed, Skipped);
591 
592     // If the skipped block has no labels in it, just emit the executed block.
593     // This avoids emitting dead code and simplifies the CFG substantially.
594     if (S.isConstexpr() || !ContainsLabel(Skipped)) {
595       if (CondConstant)
596         incrementProfileCounter(&S);
597       if (Executed) {
598         RunCleanupsScope ExecutedScope(*this);
599         EmitStmt(Executed);
600       }
601       return;
602     }
603   }
604 
605   // Otherwise, the condition did not fold, or we couldn't elide it.  Just emit
606   // the conditional branch.
607   llvm::BasicBlock *ThenBlock = createBasicBlock("if.then");
608   llvm::BasicBlock *ContBlock = createBasicBlock("if.end");
609   llvm::BasicBlock *ElseBlock = ContBlock;
610   if (S.getElse())
611     ElseBlock = createBasicBlock("if.else");
612 
613   EmitBranchOnBoolExpr(S.getCond(), ThenBlock, ElseBlock,
614                        getProfileCount(S.getThen()));
615 
616   // Emit the 'then' code.
617   EmitBlock(ThenBlock);
618   incrementProfileCounter(&S);
619   {
620     RunCleanupsScope ThenScope(*this);
621     EmitStmt(S.getThen());
622   }
623   {
624     auto CurBlock = Builder.GetInsertBlock();
625     EmitBranch(ContBlock);
626     // Eliminate any empty blocks that may have been created by nested
627     // control flow statements in the 'then' clause.
628     if (CurBlock)
629       SimplifyForwardingBlocks(CurBlock);
630   }
631 
632   // Emit the 'else' code if present.
633   if (const Stmt *Else = S.getElse()) {
634     {
635       // There is no need to emit line number for an unconditional branch.
636       auto NL = ApplyDebugLocation::CreateEmpty(*this);
637       EmitBlock(ElseBlock);
638     }
639     {
640       RunCleanupsScope ElseScope(*this);
641       EmitStmt(Else);
642     }
643     {
644       // There is no need to emit line number for an unconditional branch.
645       auto NL = ApplyDebugLocation::CreateEmpty(*this);
646       auto CurBlock = Builder.GetInsertBlock();
647       EmitBranch(ContBlock);
648       // Eliminate any empty blocks that may have been created by nested
649       // control flow statements emitted in the 'else' clause.
650       if (CurBlock)
651         SimplifyForwardingBlocks(CurBlock);
652     }
653   }
654 
655   // Emit the continuation block for code after the if.
656   EmitBlock(ContBlock, true);
657 }
658 
EmitWhileStmt(const WhileStmt & S,ArrayRef<const Attr * > WhileAttrs)659 void CodeGenFunction::EmitWhileStmt(const WhileStmt &S,
660                                     ArrayRef<const Attr *> WhileAttrs) {
661   // Emit the header for the loop, which will also become
662   // the continue target.
663   JumpDest LoopHeader = getJumpDestInCurrentScope("while.cond");
664   EmitBlock(LoopHeader.getBlock());
665 
666   LoopStack.push(LoopHeader.getBlock(), CGM.getContext(), WhileAttrs,
667                  Builder.getCurrentDebugLocation());
668 
669   // Create an exit block for when the condition fails, which will
670   // also become the break target.
671   JumpDest LoopExit = getJumpDestInCurrentScope("while.end");
672 
673   // Store the blocks to use for break and continue.
674   BreakContinueStack.push_back(BreakContinue(LoopExit, LoopHeader));
675 
676   // C++ [stmt.while]p2:
677   //   When the condition of a while statement is a declaration, the
678   //   scope of the variable that is declared extends from its point
679   //   of declaration (3.3.2) to the end of the while statement.
680   //   [...]
681   //   The object created in a condition is destroyed and created
682   //   with each iteration of the loop.
683   RunCleanupsScope ConditionScope(*this);
684 
685   if (S.getConditionVariable())
686     EmitAutoVarDecl(*S.getConditionVariable());
687 
688   // Evaluate the conditional in the while header.  C99 6.8.5.1: The
689   // evaluation of the controlling expression takes place before each
690   // execution of the loop body.
691   llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
692 
693   // while(1) is common, avoid extra exit blocks.  Be sure
694   // to correctly handle break/continue though.
695   bool EmitBoolCondBranch = true;
696   if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal))
697     if (C->isOne())
698       EmitBoolCondBranch = false;
699 
700   // As long as the condition is true, go to the loop body.
701   llvm::BasicBlock *LoopBody = createBasicBlock("while.body");
702   if (EmitBoolCondBranch) {
703     llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
704     if (ConditionScope.requiresCleanups())
705       ExitBlock = createBasicBlock("while.exit");
706     Builder.CreateCondBr(
707         BoolCondVal, LoopBody, ExitBlock,
708         createProfileWeightsForLoop(S.getCond(), getProfileCount(S.getBody())));
709 
710     if (ExitBlock != LoopExit.getBlock()) {
711       EmitBlock(ExitBlock);
712       EmitBranchThroughCleanup(LoopExit);
713     }
714   }
715 
716   // Emit the loop body.  We have to emit this in a cleanup scope
717   // because it might be a singleton DeclStmt.
718   {
719     RunCleanupsScope BodyScope(*this);
720     EmitBlock(LoopBody);
721     incrementProfileCounter(&S);
722     EmitStmt(S.getBody());
723   }
724 
725   BreakContinueStack.pop_back();
726 
727   // Immediately force cleanup.
728   ConditionScope.ForceCleanup();
729 
730   EmitStopPoint(&S);
731   // Branch to the loop header again.
732   EmitBranch(LoopHeader.getBlock());
733 
734   LoopStack.pop();
735 
736   // Emit the exit block.
737   EmitBlock(LoopExit.getBlock(), true);
738 
739   // The LoopHeader typically is just a branch if we skipped emitting
740   // a branch, try to erase it.
741   if (!EmitBoolCondBranch)
742     SimplifyForwardingBlocks(LoopHeader.getBlock());
743 }
744 
EmitDoStmt(const DoStmt & S,ArrayRef<const Attr * > DoAttrs)745 void CodeGenFunction::EmitDoStmt(const DoStmt &S,
746                                  ArrayRef<const Attr *> DoAttrs) {
747   JumpDest LoopExit = getJumpDestInCurrentScope("do.end");
748   JumpDest LoopCond = getJumpDestInCurrentScope("do.cond");
749 
750   uint64_t ParentCount = getCurrentProfileCount();
751 
752   // Store the blocks to use for break and continue.
753   BreakContinueStack.push_back(BreakContinue(LoopExit, LoopCond));
754 
755   // Emit the body of the loop.
756   llvm::BasicBlock *LoopBody = createBasicBlock("do.body");
757 
758   LoopStack.push(LoopBody, CGM.getContext(), DoAttrs,
759                  Builder.getCurrentDebugLocation());
760 
761   EmitBlockWithFallThrough(LoopBody, &S);
762   {
763     RunCleanupsScope BodyScope(*this);
764     EmitStmt(S.getBody());
765   }
766 
767   EmitBlock(LoopCond.getBlock());
768 
769   // C99 6.8.5.2: "The evaluation of the controlling expression takes place
770   // after each execution of the loop body."
771 
772   // Evaluate the conditional in the while header.
773   // C99 6.8.5p2/p4: The first substatement is executed if the expression
774   // compares unequal to 0.  The condition must be a scalar type.
775   llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
776 
777   BreakContinueStack.pop_back();
778 
779   // "do {} while (0)" is common in macros, avoid extra blocks.  Be sure
780   // to correctly handle break/continue though.
781   bool EmitBoolCondBranch = true;
782   if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal))
783     if (C->isZero())
784       EmitBoolCondBranch = false;
785 
786   // As long as the condition is true, iterate the loop.
787   if (EmitBoolCondBranch) {
788     uint64_t BackedgeCount = getProfileCount(S.getBody()) - ParentCount;
789     Builder.CreateCondBr(
790         BoolCondVal, LoopBody, LoopExit.getBlock(),
791         createProfileWeightsForLoop(S.getCond(), BackedgeCount));
792   }
793 
794   LoopStack.pop();
795 
796   // Emit the exit block.
797   EmitBlock(LoopExit.getBlock());
798 
799   // The DoCond block typically is just a branch if we skipped
800   // emitting a branch, try to erase it.
801   if (!EmitBoolCondBranch)
802     SimplifyForwardingBlocks(LoopCond.getBlock());
803 }
804 
EmitForStmt(const ForStmt & S,ArrayRef<const Attr * > ForAttrs)805 void CodeGenFunction::EmitForStmt(const ForStmt &S,
806                                   ArrayRef<const Attr *> ForAttrs) {
807   JumpDest LoopExit = getJumpDestInCurrentScope("for.end");
808 
809   LexicalScope ForScope(*this, S.getSourceRange());
810 
811   llvm::DebugLoc DL = Builder.getCurrentDebugLocation();
812 
813   // Evaluate the first part before the loop.
814   if (S.getInit())
815     EmitStmt(S.getInit());
816 
817   // Start the loop with a block that tests the condition.
818   // If there's an increment, the continue scope will be overwritten
819   // later.
820   JumpDest Continue = getJumpDestInCurrentScope("for.cond");
821   llvm::BasicBlock *CondBlock = Continue.getBlock();
822   EmitBlock(CondBlock);
823 
824   LoopStack.push(CondBlock, CGM.getContext(), ForAttrs, DL);
825 
826   // If the for loop doesn't have an increment we can just use the
827   // condition as the continue block.  Otherwise we'll need to create
828   // a block for it (in the current scope, i.e. in the scope of the
829   // condition), and that we will become our continue block.
830   if (S.getInc())
831     Continue = getJumpDestInCurrentScope("for.inc");
832 
833   // Store the blocks to use for break and continue.
834   BreakContinueStack.push_back(BreakContinue(LoopExit, Continue));
835 
836   // Create a cleanup scope for the condition variable cleanups.
837   LexicalScope ConditionScope(*this, S.getSourceRange());
838 
839   if (S.getCond()) {
840     // If the for statement has a condition scope, emit the local variable
841     // declaration.
842     if (S.getConditionVariable()) {
843       EmitAutoVarDecl(*S.getConditionVariable());
844     }
845 
846     llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
847     // If there are any cleanups between here and the loop-exit scope,
848     // create a block to stage a loop exit along.
849     if (ForScope.requiresCleanups())
850       ExitBlock = createBasicBlock("for.cond.cleanup");
851 
852     // As long as the condition is true, iterate the loop.
853     llvm::BasicBlock *ForBody = createBasicBlock("for.body");
854 
855     // C99 6.8.5p2/p4: The first substatement is executed if the expression
856     // compares unequal to 0.  The condition must be a scalar type.
857     llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
858     Builder.CreateCondBr(
859         BoolCondVal, ForBody, ExitBlock,
860         createProfileWeightsForLoop(S.getCond(), getProfileCount(S.getBody())));
861 
862     if (ExitBlock != LoopExit.getBlock()) {
863       EmitBlock(ExitBlock);
864       EmitBranchThroughCleanup(LoopExit);
865     }
866 
867     EmitBlock(ForBody);
868   } else {
869     // Treat it as a non-zero constant.  Don't even create a new block for the
870     // body, just fall into it.
871   }
872   incrementProfileCounter(&S);
873 
874   {
875     // Create a separate cleanup scope for the body, in case it is not
876     // a compound statement.
877     RunCleanupsScope BodyScope(*this);
878     EmitStmt(S.getBody());
879   }
880 
881   // If there is an increment, emit it next.
882   if (S.getInc()) {
883     EmitBlock(Continue.getBlock());
884     EmitStmt(S.getInc());
885   }
886 
887   BreakContinueStack.pop_back();
888 
889   ConditionScope.ForceCleanup();
890 
891   EmitStopPoint(&S);
892   EmitBranch(CondBlock);
893 
894   ForScope.ForceCleanup();
895 
896   LoopStack.pop();
897 
898   // Emit the fall-through block.
899   EmitBlock(LoopExit.getBlock(), true);
900 }
901 
902 void
EmitCXXForRangeStmt(const CXXForRangeStmt & S,ArrayRef<const Attr * > ForAttrs)903 CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S,
904                                      ArrayRef<const Attr *> ForAttrs) {
905   JumpDest LoopExit = getJumpDestInCurrentScope("for.end");
906 
907   LexicalScope ForScope(*this, S.getSourceRange());
908 
909   llvm::DebugLoc DL = Builder.getCurrentDebugLocation();
910 
911   // Evaluate the first pieces before the loop.
912   EmitStmt(S.getRangeStmt());
913   EmitStmt(S.getBeginStmt());
914   EmitStmt(S.getEndStmt());
915 
916   // Start the loop with a block that tests the condition.
917   // If there's an increment, the continue scope will be overwritten
918   // later.
919   llvm::BasicBlock *CondBlock = createBasicBlock("for.cond");
920   EmitBlock(CondBlock);
921 
922   LoopStack.push(CondBlock, CGM.getContext(), ForAttrs, DL);
923 
924   // If there are any cleanups between here and the loop-exit scope,
925   // create a block to stage a loop exit along.
926   llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
927   if (ForScope.requiresCleanups())
928     ExitBlock = createBasicBlock("for.cond.cleanup");
929 
930   // The loop body, consisting of the specified body and the loop variable.
931   llvm::BasicBlock *ForBody = createBasicBlock("for.body");
932 
933   // The body is executed if the expression, contextually converted
934   // to bool, is true.
935   llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
936   Builder.CreateCondBr(
937       BoolCondVal, ForBody, ExitBlock,
938       createProfileWeightsForLoop(S.getCond(), getProfileCount(S.getBody())));
939 
940   if (ExitBlock != LoopExit.getBlock()) {
941     EmitBlock(ExitBlock);
942     EmitBranchThroughCleanup(LoopExit);
943   }
944 
945   EmitBlock(ForBody);
946   incrementProfileCounter(&S);
947 
948   // Create a block for the increment. In case of a 'continue', we jump there.
949   JumpDest Continue = getJumpDestInCurrentScope("for.inc");
950 
951   // Store the blocks to use for break and continue.
952   BreakContinueStack.push_back(BreakContinue(LoopExit, Continue));
953 
954   {
955     // Create a separate cleanup scope for the loop variable and body.
956     LexicalScope BodyScope(*this, S.getSourceRange());
957     EmitStmt(S.getLoopVarStmt());
958     EmitStmt(S.getBody());
959   }
960 
961   EmitStopPoint(&S);
962   // If there is an increment, emit it next.
963   EmitBlock(Continue.getBlock());
964   EmitStmt(S.getInc());
965 
966   BreakContinueStack.pop_back();
967 
968   EmitBranch(CondBlock);
969 
970   ForScope.ForceCleanup();
971 
972   LoopStack.pop();
973 
974   // Emit the fall-through block.
975   EmitBlock(LoopExit.getBlock(), true);
976 }
977 
EmitReturnOfRValue(RValue RV,QualType Ty)978 void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) {
979   if (RV.isScalar()) {
980     Builder.CreateStore(RV.getScalarVal(), ReturnValue);
981   } else if (RV.isAggregate()) {
982     EmitAggregateCopy(ReturnValue, RV.getAggregateAddress(), Ty);
983   } else {
984     EmitStoreOfComplex(RV.getComplexVal(), MakeAddrLValue(ReturnValue, Ty),
985                        /*init*/ true);
986   }
987   EmitBranchThroughCleanup(ReturnBlock);
988 }
989 
990 /// EmitReturnStmt - Note that due to GCC extensions, this can have an operand
991 /// if the function returns void, or may be missing one if the function returns
992 /// non-void.  Fun stuff :).
EmitReturnStmt(const ReturnStmt & S)993 void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) {
994   // Returning from an outlined SEH helper is UB, and we already warn on it.
995   if (IsOutlinedSEHHelper) {
996     Builder.CreateUnreachable();
997     Builder.ClearInsertionPoint();
998   }
999 
1000   // Emit the result value, even if unused, to evalute the side effects.
1001   const Expr *RV = S.getRetValue();
1002 
1003   // Treat block literals in a return expression as if they appeared
1004   // in their own scope.  This permits a small, easily-implemented
1005   // exception to our over-conservative rules about not jumping to
1006   // statements following block literals with non-trivial cleanups.
1007   RunCleanupsScope cleanupScope(*this);
1008   if (const ExprWithCleanups *cleanups =
1009         dyn_cast_or_null<ExprWithCleanups>(RV)) {
1010     enterFullExpression(cleanups);
1011     RV = cleanups->getSubExpr();
1012   }
1013 
1014   // FIXME: Clean this up by using an LValue for ReturnTemp,
1015   // EmitStoreThroughLValue, and EmitAnyExpr.
1016   if (getLangOpts().ElideConstructors &&
1017       S.getNRVOCandidate() && S.getNRVOCandidate()->isNRVOVariable()) {
1018     // Apply the named return value optimization for this return statement,
1019     // which means doing nothing: the appropriate result has already been
1020     // constructed into the NRVO variable.
1021 
1022     // If there is an NRVO flag for this variable, set it to 1 into indicate
1023     // that the cleanup code should not destroy the variable.
1024     if (llvm::Value *NRVOFlag = NRVOFlags[S.getNRVOCandidate()])
1025       Builder.CreateFlagStore(Builder.getTrue(), NRVOFlag);
1026   } else if (!ReturnValue.isValid() || (RV && RV->getType()->isVoidType())) {
1027     // Make sure not to return anything, but evaluate the expression
1028     // for side effects.
1029     if (RV)
1030       EmitAnyExpr(RV);
1031   } else if (!RV) {
1032     // Do nothing (return value is left uninitialized)
1033   } else if (FnRetTy->isReferenceType()) {
1034     // If this function returns a reference, take the address of the expression
1035     // rather than the value.
1036     RValue Result = EmitReferenceBindingToExpr(RV);
1037     Builder.CreateStore(Result.getScalarVal(), ReturnValue);
1038   } else {
1039     switch (getEvaluationKind(RV->getType())) {
1040     case TEK_Scalar:
1041       Builder.CreateStore(EmitScalarExpr(RV), ReturnValue);
1042       break;
1043     case TEK_Complex:
1044       EmitComplexExprIntoLValue(RV, MakeAddrLValue(ReturnValue, RV->getType()),
1045                                 /*isInit*/ true);
1046       break;
1047     case TEK_Aggregate:
1048       EmitAggExpr(RV, AggValueSlot::forAddr(ReturnValue,
1049                                             Qualifiers(),
1050                                             AggValueSlot::IsDestructed,
1051                                             AggValueSlot::DoesNotNeedGCBarriers,
1052                                             AggValueSlot::IsNotAliased));
1053       break;
1054     }
1055   }
1056 
1057   ++NumReturnExprs;
1058   if (!RV || RV->isEvaluatable(getContext()))
1059     ++NumSimpleReturnExprs;
1060 
1061   cleanupScope.ForceCleanup();
1062   EmitBranchThroughCleanup(ReturnBlock);
1063 }
1064 
EmitDeclStmt(const DeclStmt & S)1065 void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) {
1066   // As long as debug info is modeled with instructions, we have to ensure we
1067   // have a place to insert here and write the stop point here.
1068   if (HaveInsertPoint())
1069     EmitStopPoint(&S);
1070 
1071   for (const auto *I : S.decls())
1072     EmitDecl(*I);
1073 }
1074 
EmitBreakStmt(const BreakStmt & S)1075 void CodeGenFunction::EmitBreakStmt(const BreakStmt &S) {
1076   assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!");
1077 
1078   // If this code is reachable then emit a stop point (if generating
1079   // debug info). We have to do this ourselves because we are on the
1080   // "simple" statement path.
1081   if (HaveInsertPoint())
1082     EmitStopPoint(&S);
1083 
1084   EmitBranchThroughCleanup(BreakContinueStack.back().BreakBlock);
1085 }
1086 
EmitContinueStmt(const ContinueStmt & S)1087 void CodeGenFunction::EmitContinueStmt(const ContinueStmt &S) {
1088   assert(!BreakContinueStack.empty() && "continue stmt not in a loop!");
1089 
1090   // If this code is reachable then emit a stop point (if generating
1091   // debug info). We have to do this ourselves because we are on the
1092   // "simple" statement path.
1093   if (HaveInsertPoint())
1094     EmitStopPoint(&S);
1095 
1096   EmitBranchThroughCleanup(BreakContinueStack.back().ContinueBlock);
1097 }
1098 
1099 /// EmitCaseStmtRange - If case statement range is not too big then
1100 /// add multiple cases to switch instruction, one for each value within
1101 /// the range. If range is too big then emit "if" condition check.
EmitCaseStmtRange(const CaseStmt & S)1102 void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) {
1103   assert(S.getRHS() && "Expected RHS value in CaseStmt");
1104 
1105   llvm::APSInt LHS = S.getLHS()->EvaluateKnownConstInt(getContext());
1106   llvm::APSInt RHS = S.getRHS()->EvaluateKnownConstInt(getContext());
1107 
1108   // Emit the code for this case. We do this first to make sure it is
1109   // properly chained from our predecessor before generating the
1110   // switch machinery to enter this block.
1111   llvm::BasicBlock *CaseDest = createBasicBlock("sw.bb");
1112   EmitBlockWithFallThrough(CaseDest, &S);
1113   EmitStmt(S.getSubStmt());
1114 
1115   // If range is empty, do nothing.
1116   if (LHS.isSigned() ? RHS.slt(LHS) : RHS.ult(LHS))
1117     return;
1118 
1119   llvm::APInt Range = RHS - LHS;
1120   // FIXME: parameters such as this should not be hardcoded.
1121   if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) {
1122     // Range is small enough to add multiple switch instruction cases.
1123     uint64_t Total = getProfileCount(&S);
1124     unsigned NCases = Range.getZExtValue() + 1;
1125     // We only have one region counter for the entire set of cases here, so we
1126     // need to divide the weights evenly between the generated cases, ensuring
1127     // that the total weight is preserved. E.g., a weight of 5 over three cases
1128     // will be distributed as weights of 2, 2, and 1.
1129     uint64_t Weight = Total / NCases, Rem = Total % NCases;
1130     for (unsigned I = 0; I != NCases; ++I) {
1131       if (SwitchWeights)
1132         SwitchWeights->push_back(Weight + (Rem ? 1 : 0));
1133       if (Rem)
1134         Rem--;
1135       SwitchInsn->addCase(Builder.getInt(LHS), CaseDest);
1136       LHS++;
1137     }
1138     return;
1139   }
1140 
1141   // The range is too big. Emit "if" condition into a new block,
1142   // making sure to save and restore the current insertion point.
1143   llvm::BasicBlock *RestoreBB = Builder.GetInsertBlock();
1144 
1145   // Push this test onto the chain of range checks (which terminates
1146   // in the default basic block). The switch's default will be changed
1147   // to the top of this chain after switch emission is complete.
1148   llvm::BasicBlock *FalseDest = CaseRangeBlock;
1149   CaseRangeBlock = createBasicBlock("sw.caserange");
1150 
1151   CurFn->getBasicBlockList().push_back(CaseRangeBlock);
1152   Builder.SetInsertPoint(CaseRangeBlock);
1153 
1154   // Emit range check.
1155   llvm::Value *Diff =
1156     Builder.CreateSub(SwitchInsn->getCondition(), Builder.getInt(LHS));
1157   llvm::Value *Cond =
1158     Builder.CreateICmpULE(Diff, Builder.getInt(Range), "inbounds");
1159 
1160   llvm::MDNode *Weights = nullptr;
1161   if (SwitchWeights) {
1162     uint64_t ThisCount = getProfileCount(&S);
1163     uint64_t DefaultCount = (*SwitchWeights)[0];
1164     Weights = createProfileWeights(ThisCount, DefaultCount);
1165 
1166     // Since we're chaining the switch default through each large case range, we
1167     // need to update the weight for the default, ie, the first case, to include
1168     // this case.
1169     (*SwitchWeights)[0] += ThisCount;
1170   }
1171   Builder.CreateCondBr(Cond, CaseDest, FalseDest, Weights);
1172 
1173   // Restore the appropriate insertion point.
1174   if (RestoreBB)
1175     Builder.SetInsertPoint(RestoreBB);
1176   else
1177     Builder.ClearInsertionPoint();
1178 }
1179 
EmitCaseStmt(const CaseStmt & S)1180 void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) {
1181   // If there is no enclosing switch instance that we're aware of, then this
1182   // case statement and its block can be elided.  This situation only happens
1183   // when we've constant-folded the switch, are emitting the constant case,
1184   // and part of the constant case includes another case statement.  For
1185   // instance: switch (4) { case 4: do { case 5: } while (1); }
1186   if (!SwitchInsn) {
1187     EmitStmt(S.getSubStmt());
1188     return;
1189   }
1190 
1191   // Handle case ranges.
1192   if (S.getRHS()) {
1193     EmitCaseStmtRange(S);
1194     return;
1195   }
1196 
1197   llvm::ConstantInt *CaseVal =
1198     Builder.getInt(S.getLHS()->EvaluateKnownConstInt(getContext()));
1199 
1200   // If the body of the case is just a 'break', try to not emit an empty block.
1201   // If we're profiling or we're not optimizing, leave the block in for better
1202   // debug and coverage analysis.
1203   if (!CGM.getCodeGenOpts().hasProfileClangInstr() &&
1204       CGM.getCodeGenOpts().OptimizationLevel > 0 &&
1205       isa<BreakStmt>(S.getSubStmt())) {
1206     JumpDest Block = BreakContinueStack.back().BreakBlock;
1207 
1208     // Only do this optimization if there are no cleanups that need emitting.
1209     if (isObviouslyBranchWithoutCleanups(Block)) {
1210       if (SwitchWeights)
1211         SwitchWeights->push_back(getProfileCount(&S));
1212       SwitchInsn->addCase(CaseVal, Block.getBlock());
1213 
1214       // If there was a fallthrough into this case, make sure to redirect it to
1215       // the end of the switch as well.
1216       if (Builder.GetInsertBlock()) {
1217         Builder.CreateBr(Block.getBlock());
1218         Builder.ClearInsertionPoint();
1219       }
1220       return;
1221     }
1222   }
1223 
1224   llvm::BasicBlock *CaseDest = createBasicBlock("sw.bb");
1225   EmitBlockWithFallThrough(CaseDest, &S);
1226   if (SwitchWeights)
1227     SwitchWeights->push_back(getProfileCount(&S));
1228   SwitchInsn->addCase(CaseVal, CaseDest);
1229 
1230   // Recursively emitting the statement is acceptable, but is not wonderful for
1231   // code where we have many case statements nested together, i.e.:
1232   //  case 1:
1233   //    case 2:
1234   //      case 3: etc.
1235   // Handling this recursively will create a new block for each case statement
1236   // that falls through to the next case which is IR intensive.  It also causes
1237   // deep recursion which can run into stack depth limitations.  Handle
1238   // sequential non-range case statements specially.
1239   const CaseStmt *CurCase = &S;
1240   const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt());
1241 
1242   // Otherwise, iteratively add consecutive cases to this switch stmt.
1243   while (NextCase && NextCase->getRHS() == nullptr) {
1244     CurCase = NextCase;
1245     llvm::ConstantInt *CaseVal =
1246       Builder.getInt(CurCase->getLHS()->EvaluateKnownConstInt(getContext()));
1247 
1248     if (SwitchWeights)
1249       SwitchWeights->push_back(getProfileCount(NextCase));
1250     if (CGM.getCodeGenOpts().hasProfileClangInstr()) {
1251       CaseDest = createBasicBlock("sw.bb");
1252       EmitBlockWithFallThrough(CaseDest, &S);
1253     }
1254 
1255     SwitchInsn->addCase(CaseVal, CaseDest);
1256     NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt());
1257   }
1258 
1259   // Normal default recursion for non-cases.
1260   EmitStmt(CurCase->getSubStmt());
1261 }
1262 
EmitDefaultStmt(const DefaultStmt & S)1263 void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) {
1264   llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest();
1265   assert(DefaultBlock->empty() &&
1266          "EmitDefaultStmt: Default block already defined?");
1267 
1268   EmitBlockWithFallThrough(DefaultBlock, &S);
1269 
1270   EmitStmt(S.getSubStmt());
1271 }
1272 
1273 /// CollectStatementsForCase - Given the body of a 'switch' statement and a
1274 /// constant value that is being switched on, see if we can dead code eliminate
1275 /// the body of the switch to a simple series of statements to emit.  Basically,
1276 /// on a switch (5) we want to find these statements:
1277 ///    case 5:
1278 ///      printf(...);    <--
1279 ///      ++i;            <--
1280 ///      break;
1281 ///
1282 /// and add them to the ResultStmts vector.  If it is unsafe to do this
1283 /// transformation (for example, one of the elided statements contains a label
1284 /// that might be jumped to), return CSFC_Failure.  If we handled it and 'S'
1285 /// should include statements after it (e.g. the printf() line is a substmt of
1286 /// the case) then return CSFC_FallThrough.  If we handled it and found a break
1287 /// statement, then return CSFC_Success.
1288 ///
1289 /// If Case is non-null, then we are looking for the specified case, checking
1290 /// that nothing we jump over contains labels.  If Case is null, then we found
1291 /// the case and are looking for the break.
1292 ///
1293 /// If the recursive walk actually finds our Case, then we set FoundCase to
1294 /// true.
1295 ///
1296 enum CSFC_Result { CSFC_Failure, CSFC_FallThrough, CSFC_Success };
CollectStatementsForCase(const Stmt * S,const SwitchCase * Case,bool & FoundCase,SmallVectorImpl<const Stmt * > & ResultStmts)1297 static CSFC_Result CollectStatementsForCase(const Stmt *S,
1298                                             const SwitchCase *Case,
1299                                             bool &FoundCase,
1300                               SmallVectorImpl<const Stmt*> &ResultStmts) {
1301   // If this is a null statement, just succeed.
1302   if (!S)
1303     return Case ? CSFC_Success : CSFC_FallThrough;
1304 
1305   // If this is the switchcase (case 4: or default) that we're looking for, then
1306   // we're in business.  Just add the substatement.
1307   if (const SwitchCase *SC = dyn_cast<SwitchCase>(S)) {
1308     if (S == Case) {
1309       FoundCase = true;
1310       return CollectStatementsForCase(SC->getSubStmt(), nullptr, FoundCase,
1311                                       ResultStmts);
1312     }
1313 
1314     // Otherwise, this is some other case or default statement, just ignore it.
1315     return CollectStatementsForCase(SC->getSubStmt(), Case, FoundCase,
1316                                     ResultStmts);
1317   }
1318 
1319   // If we are in the live part of the code and we found our break statement,
1320   // return a success!
1321   if (!Case && isa<BreakStmt>(S))
1322     return CSFC_Success;
1323 
1324   // If this is a switch statement, then it might contain the SwitchCase, the
1325   // break, or neither.
1326   if (const CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) {
1327     // Handle this as two cases: we might be looking for the SwitchCase (if so
1328     // the skipped statements must be skippable) or we might already have it.
1329     CompoundStmt::const_body_iterator I = CS->body_begin(), E = CS->body_end();
1330     if (Case) {
1331       // Keep track of whether we see a skipped declaration.  The code could be
1332       // using the declaration even if it is skipped, so we can't optimize out
1333       // the decl if the kept statements might refer to it.
1334       bool HadSkippedDecl = false;
1335 
1336       // If we're looking for the case, just see if we can skip each of the
1337       // substatements.
1338       for (; Case && I != E; ++I) {
1339         HadSkippedDecl |= isa<DeclStmt>(*I);
1340 
1341         switch (CollectStatementsForCase(*I, Case, FoundCase, ResultStmts)) {
1342         case CSFC_Failure: return CSFC_Failure;
1343         case CSFC_Success:
1344           // A successful result means that either 1) that the statement doesn't
1345           // have the case and is skippable, or 2) does contain the case value
1346           // and also contains the break to exit the switch.  In the later case,
1347           // we just verify the rest of the statements are elidable.
1348           if (FoundCase) {
1349             // If we found the case and skipped declarations, we can't do the
1350             // optimization.
1351             if (HadSkippedDecl)
1352               return CSFC_Failure;
1353 
1354             for (++I; I != E; ++I)
1355               if (CodeGenFunction::ContainsLabel(*I, true))
1356                 return CSFC_Failure;
1357             return CSFC_Success;
1358           }
1359           break;
1360         case CSFC_FallThrough:
1361           // If we have a fallthrough condition, then we must have found the
1362           // case started to include statements.  Consider the rest of the
1363           // statements in the compound statement as candidates for inclusion.
1364           assert(FoundCase && "Didn't find case but returned fallthrough?");
1365           // We recursively found Case, so we're not looking for it anymore.
1366           Case = nullptr;
1367 
1368           // If we found the case and skipped declarations, we can't do the
1369           // optimization.
1370           if (HadSkippedDecl)
1371             return CSFC_Failure;
1372           break;
1373         }
1374       }
1375     }
1376 
1377     // If we have statements in our range, then we know that the statements are
1378     // live and need to be added to the set of statements we're tracking.
1379     for (; I != E; ++I) {
1380       switch (CollectStatementsForCase(*I, nullptr, FoundCase, ResultStmts)) {
1381       case CSFC_Failure: return CSFC_Failure;
1382       case CSFC_FallThrough:
1383         // A fallthrough result means that the statement was simple and just
1384         // included in ResultStmt, keep adding them afterwards.
1385         break;
1386       case CSFC_Success:
1387         // A successful result means that we found the break statement and
1388         // stopped statement inclusion.  We just ensure that any leftover stmts
1389         // are skippable and return success ourselves.
1390         for (++I; I != E; ++I)
1391           if (CodeGenFunction::ContainsLabel(*I, true))
1392             return CSFC_Failure;
1393         return CSFC_Success;
1394       }
1395     }
1396 
1397     return Case ? CSFC_Success : CSFC_FallThrough;
1398   }
1399 
1400   // Okay, this is some other statement that we don't handle explicitly, like a
1401   // for statement or increment etc.  If we are skipping over this statement,
1402   // just verify it doesn't have labels, which would make it invalid to elide.
1403   if (Case) {
1404     if (CodeGenFunction::ContainsLabel(S, true))
1405       return CSFC_Failure;
1406     return CSFC_Success;
1407   }
1408 
1409   // Otherwise, we want to include this statement.  Everything is cool with that
1410   // so long as it doesn't contain a break out of the switch we're in.
1411   if (CodeGenFunction::containsBreak(S)) return CSFC_Failure;
1412 
1413   // Otherwise, everything is great.  Include the statement and tell the caller
1414   // that we fall through and include the next statement as well.
1415   ResultStmts.push_back(S);
1416   return CSFC_FallThrough;
1417 }
1418 
1419 /// FindCaseStatementsForValue - Find the case statement being jumped to and
1420 /// then invoke CollectStatementsForCase to find the list of statements to emit
1421 /// for a switch on constant.  See the comment above CollectStatementsForCase
1422 /// for more details.
FindCaseStatementsForValue(const SwitchStmt & S,const llvm::APSInt & ConstantCondValue,SmallVectorImpl<const Stmt * > & ResultStmts,ASTContext & C,const SwitchCase * & ResultCase)1423 static bool FindCaseStatementsForValue(const SwitchStmt &S,
1424                                        const llvm::APSInt &ConstantCondValue,
1425                                 SmallVectorImpl<const Stmt*> &ResultStmts,
1426                                        ASTContext &C,
1427                                        const SwitchCase *&ResultCase) {
1428   // First step, find the switch case that is being branched to.  We can do this
1429   // efficiently by scanning the SwitchCase list.
1430   const SwitchCase *Case = S.getSwitchCaseList();
1431   const DefaultStmt *DefaultCase = nullptr;
1432 
1433   for (; Case; Case = Case->getNextSwitchCase()) {
1434     // It's either a default or case.  Just remember the default statement in
1435     // case we're not jumping to any numbered cases.
1436     if (const DefaultStmt *DS = dyn_cast<DefaultStmt>(Case)) {
1437       DefaultCase = DS;
1438       continue;
1439     }
1440 
1441     // Check to see if this case is the one we're looking for.
1442     const CaseStmt *CS = cast<CaseStmt>(Case);
1443     // Don't handle case ranges yet.
1444     if (CS->getRHS()) return false;
1445 
1446     // If we found our case, remember it as 'case'.
1447     if (CS->getLHS()->EvaluateKnownConstInt(C) == ConstantCondValue)
1448       break;
1449   }
1450 
1451   // If we didn't find a matching case, we use a default if it exists, or we
1452   // elide the whole switch body!
1453   if (!Case) {
1454     // It is safe to elide the body of the switch if it doesn't contain labels
1455     // etc.  If it is safe, return successfully with an empty ResultStmts list.
1456     if (!DefaultCase)
1457       return !CodeGenFunction::ContainsLabel(&S);
1458     Case = DefaultCase;
1459   }
1460 
1461   // Ok, we know which case is being jumped to, try to collect all the
1462   // statements that follow it.  This can fail for a variety of reasons.  Also,
1463   // check to see that the recursive walk actually found our case statement.
1464   // Insane cases like this can fail to find it in the recursive walk since we
1465   // don't handle every stmt kind:
1466   // switch (4) {
1467   //   while (1) {
1468   //     case 4: ...
1469   bool FoundCase = false;
1470   ResultCase = Case;
1471   return CollectStatementsForCase(S.getBody(), Case, FoundCase,
1472                                   ResultStmts) != CSFC_Failure &&
1473          FoundCase;
1474 }
1475 
EmitSwitchStmt(const SwitchStmt & S)1476 void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) {
1477   // Handle nested switch statements.
1478   llvm::SwitchInst *SavedSwitchInsn = SwitchInsn;
1479   SmallVector<uint64_t, 16> *SavedSwitchWeights = SwitchWeights;
1480   llvm::BasicBlock *SavedCRBlock = CaseRangeBlock;
1481 
1482   // See if we can constant fold the condition of the switch and therefore only
1483   // emit the live case statement (if any) of the switch.
1484   llvm::APSInt ConstantCondValue;
1485   if (ConstantFoldsToSimpleInteger(S.getCond(), ConstantCondValue)) {
1486     SmallVector<const Stmt*, 4> CaseStmts;
1487     const SwitchCase *Case = nullptr;
1488     if (FindCaseStatementsForValue(S, ConstantCondValue, CaseStmts,
1489                                    getContext(), Case)) {
1490       if (Case)
1491         incrementProfileCounter(Case);
1492       RunCleanupsScope ExecutedScope(*this);
1493 
1494       if (S.getInit())
1495         EmitStmt(S.getInit());
1496 
1497       // Emit the condition variable if needed inside the entire cleanup scope
1498       // used by this special case for constant folded switches.
1499       if (S.getConditionVariable())
1500         EmitAutoVarDecl(*S.getConditionVariable());
1501 
1502       // At this point, we are no longer "within" a switch instance, so
1503       // we can temporarily enforce this to ensure that any embedded case
1504       // statements are not emitted.
1505       SwitchInsn = nullptr;
1506 
1507       // Okay, we can dead code eliminate everything except this case.  Emit the
1508       // specified series of statements and we're good.
1509       for (unsigned i = 0, e = CaseStmts.size(); i != e; ++i)
1510         EmitStmt(CaseStmts[i]);
1511       incrementProfileCounter(&S);
1512 
1513       // Now we want to restore the saved switch instance so that nested
1514       // switches continue to function properly
1515       SwitchInsn = SavedSwitchInsn;
1516 
1517       return;
1518     }
1519   }
1520 
1521   JumpDest SwitchExit = getJumpDestInCurrentScope("sw.epilog");
1522 
1523   RunCleanupsScope ConditionScope(*this);
1524 
1525   if (S.getInit())
1526     EmitStmt(S.getInit());
1527 
1528   if (S.getConditionVariable())
1529     EmitAutoVarDecl(*S.getConditionVariable());
1530   llvm::Value *CondV = EmitScalarExpr(S.getCond());
1531 
1532   // Create basic block to hold stuff that comes after switch
1533   // statement. We also need to create a default block now so that
1534   // explicit case ranges tests can have a place to jump to on
1535   // failure.
1536   llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default");
1537   SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock);
1538   if (PGO.haveRegionCounts()) {
1539     // Walk the SwitchCase list to find how many there are.
1540     uint64_t DefaultCount = 0;
1541     unsigned NumCases = 0;
1542     for (const SwitchCase *Case = S.getSwitchCaseList();
1543          Case;
1544          Case = Case->getNextSwitchCase()) {
1545       if (isa<DefaultStmt>(Case))
1546         DefaultCount = getProfileCount(Case);
1547       NumCases += 1;
1548     }
1549     SwitchWeights = new SmallVector<uint64_t, 16>();
1550     SwitchWeights->reserve(NumCases);
1551     // The default needs to be first. We store the edge count, so we already
1552     // know the right weight.
1553     SwitchWeights->push_back(DefaultCount);
1554   }
1555   CaseRangeBlock = DefaultBlock;
1556 
1557   // Clear the insertion point to indicate we are in unreachable code.
1558   Builder.ClearInsertionPoint();
1559 
1560   // All break statements jump to NextBlock. If BreakContinueStack is non-empty
1561   // then reuse last ContinueBlock.
1562   JumpDest OuterContinue;
1563   if (!BreakContinueStack.empty())
1564     OuterContinue = BreakContinueStack.back().ContinueBlock;
1565 
1566   BreakContinueStack.push_back(BreakContinue(SwitchExit, OuterContinue));
1567 
1568   // Emit switch body.
1569   EmitStmt(S.getBody());
1570 
1571   BreakContinueStack.pop_back();
1572 
1573   // Update the default block in case explicit case range tests have
1574   // been chained on top.
1575   SwitchInsn->setDefaultDest(CaseRangeBlock);
1576 
1577   // If a default was never emitted:
1578   if (!DefaultBlock->getParent()) {
1579     // If we have cleanups, emit the default block so that there's a
1580     // place to jump through the cleanups from.
1581     if (ConditionScope.requiresCleanups()) {
1582       EmitBlock(DefaultBlock);
1583 
1584     // Otherwise, just forward the default block to the switch end.
1585     } else {
1586       DefaultBlock->replaceAllUsesWith(SwitchExit.getBlock());
1587       delete DefaultBlock;
1588     }
1589   }
1590 
1591   ConditionScope.ForceCleanup();
1592 
1593   // Emit continuation.
1594   EmitBlock(SwitchExit.getBlock(), true);
1595   incrementProfileCounter(&S);
1596 
1597   // If the switch has a condition wrapped by __builtin_unpredictable,
1598   // create metadata that specifies that the switch is unpredictable.
1599   // Don't bother if not optimizing because that metadata would not be used.
1600   auto *Call = dyn_cast<CallExpr>(S.getCond());
1601   if (Call && CGM.getCodeGenOpts().OptimizationLevel != 0) {
1602     auto *FD = dyn_cast_or_null<FunctionDecl>(Call->getCalleeDecl());
1603     if (FD && FD->getBuiltinID() == Builtin::BI__builtin_unpredictable) {
1604       llvm::MDBuilder MDHelper(getLLVMContext());
1605       SwitchInsn->setMetadata(llvm::LLVMContext::MD_unpredictable,
1606                               MDHelper.createUnpredictable());
1607     }
1608   }
1609 
1610   if (SwitchWeights) {
1611     assert(SwitchWeights->size() == 1 + SwitchInsn->getNumCases() &&
1612            "switch weights do not match switch cases");
1613     // If there's only one jump destination there's no sense weighting it.
1614     if (SwitchWeights->size() > 1)
1615       SwitchInsn->setMetadata(llvm::LLVMContext::MD_prof,
1616                               createProfileWeights(*SwitchWeights));
1617     delete SwitchWeights;
1618   }
1619   SwitchInsn = SavedSwitchInsn;
1620   SwitchWeights = SavedSwitchWeights;
1621   CaseRangeBlock = SavedCRBlock;
1622 }
1623 
1624 static std::string
SimplifyConstraint(const char * Constraint,const TargetInfo & Target,SmallVectorImpl<TargetInfo::ConstraintInfo> * OutCons=nullptr)1625 SimplifyConstraint(const char *Constraint, const TargetInfo &Target,
1626                  SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=nullptr) {
1627   std::string Result;
1628 
1629   while (*Constraint) {
1630     switch (*Constraint) {
1631     default:
1632       Result += Target.convertConstraint(Constraint);
1633       break;
1634     // Ignore these
1635     case '*':
1636     case '?':
1637     case '!':
1638     case '=': // Will see this and the following in mult-alt constraints.
1639     case '+':
1640       break;
1641     case '#': // Ignore the rest of the constraint alternative.
1642       while (Constraint[1] && Constraint[1] != ',')
1643         Constraint++;
1644       break;
1645     case '&':
1646     case '%':
1647       Result += *Constraint;
1648       while (Constraint[1] && Constraint[1] == *Constraint)
1649         Constraint++;
1650       break;
1651     case ',':
1652       Result += "|";
1653       break;
1654     case 'g':
1655       Result += "imr";
1656       break;
1657     case '[': {
1658       assert(OutCons &&
1659              "Must pass output names to constraints with a symbolic name");
1660       unsigned Index;
1661       bool result = Target.resolveSymbolicName(Constraint, *OutCons, Index);
1662       assert(result && "Could not resolve symbolic name"); (void)result;
1663       Result += llvm::utostr(Index);
1664       break;
1665     }
1666     }
1667 
1668     Constraint++;
1669   }
1670 
1671   return Result;
1672 }
1673 
1674 /// AddVariableConstraints - Look at AsmExpr and if it is a variable declared
1675 /// as using a particular register add that as a constraint that will be used
1676 /// in this asm stmt.
1677 static std::string
AddVariableConstraints(const std::string & Constraint,const Expr & AsmExpr,const TargetInfo & Target,CodeGenModule & CGM,const AsmStmt & Stmt,const bool EarlyClobber)1678 AddVariableConstraints(const std::string &Constraint, const Expr &AsmExpr,
1679                        const TargetInfo &Target, CodeGenModule &CGM,
1680                        const AsmStmt &Stmt, const bool EarlyClobber) {
1681   const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(&AsmExpr);
1682   if (!AsmDeclRef)
1683     return Constraint;
1684   const ValueDecl &Value = *AsmDeclRef->getDecl();
1685   const VarDecl *Variable = dyn_cast<VarDecl>(&Value);
1686   if (!Variable)
1687     return Constraint;
1688   if (Variable->getStorageClass() != SC_Register)
1689     return Constraint;
1690   AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>();
1691   if (!Attr)
1692     return Constraint;
1693   StringRef Register = Attr->getLabel();
1694   assert(Target.isValidGCCRegisterName(Register));
1695   // We're using validateOutputConstraint here because we only care if
1696   // this is a register constraint.
1697   TargetInfo::ConstraintInfo Info(Constraint, "");
1698   if (Target.validateOutputConstraint(Info) &&
1699       !Info.allowsRegister()) {
1700     CGM.ErrorUnsupported(&Stmt, "__asm__");
1701     return Constraint;
1702   }
1703   // Canonicalize the register here before returning it.
1704   Register = Target.getNormalizedGCCRegisterName(Register);
1705   return (EarlyClobber ? "&{" : "{") + Register.str() + "}";
1706 }
1707 
1708 llvm::Value*
EmitAsmInputLValue(const TargetInfo::ConstraintInfo & Info,LValue InputValue,QualType InputType,std::string & ConstraintStr,SourceLocation Loc)1709 CodeGenFunction::EmitAsmInputLValue(const TargetInfo::ConstraintInfo &Info,
1710                                     LValue InputValue, QualType InputType,
1711                                     std::string &ConstraintStr,
1712                                     SourceLocation Loc) {
1713   llvm::Value *Arg;
1714   if (Info.allowsRegister() || !Info.allowsMemory()) {
1715     if (CodeGenFunction::hasScalarEvaluationKind(InputType)) {
1716       Arg = EmitLoadOfLValue(InputValue, Loc).getScalarVal();
1717     } else {
1718       llvm::Type *Ty = ConvertType(InputType);
1719       uint64_t Size = CGM.getDataLayout().getTypeSizeInBits(Ty);
1720       if (Size <= 64 && llvm::isPowerOf2_64(Size)) {
1721         Ty = llvm::IntegerType::get(getLLVMContext(), Size);
1722         Ty = llvm::PointerType::getUnqual(Ty);
1723 
1724         Arg = Builder.CreateLoad(Builder.CreateBitCast(InputValue.getAddress(),
1725                                                        Ty));
1726       } else {
1727         Arg = InputValue.getPointer();
1728         ConstraintStr += '*';
1729       }
1730     }
1731   } else {
1732     Arg = InputValue.getPointer();
1733     ConstraintStr += '*';
1734   }
1735 
1736   return Arg;
1737 }
1738 
EmitAsmInput(const TargetInfo::ConstraintInfo & Info,const Expr * InputExpr,std::string & ConstraintStr)1739 llvm::Value* CodeGenFunction::EmitAsmInput(
1740                                          const TargetInfo::ConstraintInfo &Info,
1741                                            const Expr *InputExpr,
1742                                            std::string &ConstraintStr) {
1743   // If this can't be a register or memory, i.e., has to be a constant
1744   // (immediate or symbolic), try to emit it as such.
1745   if (!Info.allowsRegister() && !Info.allowsMemory()) {
1746     llvm::APSInt Result;
1747     if (InputExpr->EvaluateAsInt(Result, getContext()))
1748       return llvm::ConstantInt::get(getLLVMContext(), Result);
1749     assert(!Info.requiresImmediateConstant() &&
1750            "Required-immediate inlineasm arg isn't constant?");
1751   }
1752 
1753   if (Info.allowsRegister() || !Info.allowsMemory())
1754     if (CodeGenFunction::hasScalarEvaluationKind(InputExpr->getType()))
1755       return EmitScalarExpr(InputExpr);
1756   if (InputExpr->getStmtClass() == Expr::CXXThisExprClass)
1757     return EmitScalarExpr(InputExpr);
1758   InputExpr = InputExpr->IgnoreParenNoopCasts(getContext());
1759   LValue Dest = EmitLValue(InputExpr);
1760   return EmitAsmInputLValue(Info, Dest, InputExpr->getType(), ConstraintStr,
1761                             InputExpr->getExprLoc());
1762 }
1763 
1764 /// getAsmSrcLocInfo - Return the !srcloc metadata node to attach to an inline
1765 /// asm call instruction.  The !srcloc MDNode contains a list of constant
1766 /// integers which are the source locations of the start of each line in the
1767 /// asm.
getAsmSrcLocInfo(const StringLiteral * Str,CodeGenFunction & CGF)1768 static llvm::MDNode *getAsmSrcLocInfo(const StringLiteral *Str,
1769                                       CodeGenFunction &CGF) {
1770   SmallVector<llvm::Metadata *, 8> Locs;
1771   // Add the location of the first line to the MDNode.
1772   Locs.push_back(llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
1773       CGF.Int32Ty, Str->getLocStart().getRawEncoding())));
1774   StringRef StrVal = Str->getString();
1775   if (!StrVal.empty()) {
1776     const SourceManager &SM = CGF.CGM.getContext().getSourceManager();
1777     const LangOptions &LangOpts = CGF.CGM.getLangOpts();
1778     unsigned StartToken = 0;
1779     unsigned ByteOffset = 0;
1780 
1781     // Add the location of the start of each subsequent line of the asm to the
1782     // MDNode.
1783     for (unsigned i = 0, e = StrVal.size() - 1; i != e; ++i) {
1784       if (StrVal[i] != '\n') continue;
1785       SourceLocation LineLoc = Str->getLocationOfByte(
1786           i + 1, SM, LangOpts, CGF.getTarget(), &StartToken, &ByteOffset);
1787       Locs.push_back(llvm::ConstantAsMetadata::get(
1788           llvm::ConstantInt::get(CGF.Int32Ty, LineLoc.getRawEncoding())));
1789     }
1790   }
1791 
1792   return llvm::MDNode::get(CGF.getLLVMContext(), Locs);
1793 }
1794 
EmitAsmStmt(const AsmStmt & S)1795 void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {
1796   // Assemble the final asm string.
1797   std::string AsmString = S.generateAsmString(getContext());
1798 
1799   // Get all the output and input constraints together.
1800   SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1801   SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1802 
1803   for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) {
1804     StringRef Name;
1805     if (const GCCAsmStmt *GAS = dyn_cast<GCCAsmStmt>(&S))
1806       Name = GAS->getOutputName(i);
1807     TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), Name);
1808     bool IsValid = getTarget().validateOutputConstraint(Info); (void)IsValid;
1809     assert(IsValid && "Failed to parse output constraint");
1810     OutputConstraintInfos.push_back(Info);
1811   }
1812 
1813   for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) {
1814     StringRef Name;
1815     if (const GCCAsmStmt *GAS = dyn_cast<GCCAsmStmt>(&S))
1816       Name = GAS->getInputName(i);
1817     TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), Name);
1818     bool IsValid =
1819       getTarget().validateInputConstraint(OutputConstraintInfos, Info);
1820     assert(IsValid && "Failed to parse input constraint"); (void)IsValid;
1821     InputConstraintInfos.push_back(Info);
1822   }
1823 
1824   std::string Constraints;
1825 
1826   std::vector<LValue> ResultRegDests;
1827   std::vector<QualType> ResultRegQualTys;
1828   std::vector<llvm::Type *> ResultRegTypes;
1829   std::vector<llvm::Type *> ResultTruncRegTypes;
1830   std::vector<llvm::Type *> ArgTypes;
1831   std::vector<llvm::Value*> Args;
1832 
1833   // Keep track of inout constraints.
1834   std::string InOutConstraints;
1835   std::vector<llvm::Value*> InOutArgs;
1836   std::vector<llvm::Type*> InOutArgTypes;
1837 
1838   // An inline asm can be marked readonly if it meets the following conditions:
1839   //  - it doesn't have any sideeffects
1840   //  - it doesn't clobber memory
1841   //  - it doesn't return a value by-reference
1842   // It can be marked readnone if it doesn't have any input memory constraints
1843   // in addition to meeting the conditions listed above.
1844   bool ReadOnly = true, ReadNone = true;
1845 
1846   for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) {
1847     TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];
1848 
1849     // Simplify the output constraint.
1850     std::string OutputConstraint(S.getOutputConstraint(i));
1851     OutputConstraint = SimplifyConstraint(OutputConstraint.c_str() + 1,
1852                                           getTarget());
1853 
1854     const Expr *OutExpr = S.getOutputExpr(i);
1855     OutExpr = OutExpr->IgnoreParenNoopCasts(getContext());
1856 
1857     OutputConstraint = AddVariableConstraints(OutputConstraint, *OutExpr,
1858                                               getTarget(), CGM, S,
1859                                               Info.earlyClobber());
1860 
1861     LValue Dest = EmitLValue(OutExpr);
1862     if (!Constraints.empty())
1863       Constraints += ',';
1864 
1865     // If this is a register output, then make the inline asm return it
1866     // by-value.  If this is a memory result, return the value by-reference.
1867     if (!Info.allowsMemory() && hasScalarEvaluationKind(OutExpr->getType())) {
1868       Constraints += "=" + OutputConstraint;
1869       ResultRegQualTys.push_back(OutExpr->getType());
1870       ResultRegDests.push_back(Dest);
1871       ResultRegTypes.push_back(ConvertTypeForMem(OutExpr->getType()));
1872       ResultTruncRegTypes.push_back(ResultRegTypes.back());
1873 
1874       // If this output is tied to an input, and if the input is larger, then
1875       // we need to set the actual result type of the inline asm node to be the
1876       // same as the input type.
1877       if (Info.hasMatchingInput()) {
1878         unsigned InputNo;
1879         for (InputNo = 0; InputNo != S.getNumInputs(); ++InputNo) {
1880           TargetInfo::ConstraintInfo &Input = InputConstraintInfos[InputNo];
1881           if (Input.hasTiedOperand() && Input.getTiedOperand() == i)
1882             break;
1883         }
1884         assert(InputNo != S.getNumInputs() && "Didn't find matching input!");
1885 
1886         QualType InputTy = S.getInputExpr(InputNo)->getType();
1887         QualType OutputType = OutExpr->getType();
1888 
1889         uint64_t InputSize = getContext().getTypeSize(InputTy);
1890         if (getContext().getTypeSize(OutputType) < InputSize) {
1891           // Form the asm to return the value as a larger integer or fp type.
1892           ResultRegTypes.back() = ConvertType(InputTy);
1893         }
1894       }
1895       if (llvm::Type* AdjTy =
1896             getTargetHooks().adjustInlineAsmType(*this, OutputConstraint,
1897                                                  ResultRegTypes.back()))
1898         ResultRegTypes.back() = AdjTy;
1899       else {
1900         CGM.getDiags().Report(S.getAsmLoc(),
1901                               diag::err_asm_invalid_type_in_input)
1902             << OutExpr->getType() << OutputConstraint;
1903       }
1904     } else {
1905       ArgTypes.push_back(Dest.getAddress().getType());
1906       Args.push_back(Dest.getPointer());
1907       Constraints += "=*";
1908       Constraints += OutputConstraint;
1909       ReadOnly = ReadNone = false;
1910     }
1911 
1912     if (Info.isReadWrite()) {
1913       InOutConstraints += ',';
1914 
1915       const Expr *InputExpr = S.getOutputExpr(i);
1916       llvm::Value *Arg = EmitAsmInputLValue(Info, Dest, InputExpr->getType(),
1917                                             InOutConstraints,
1918                                             InputExpr->getExprLoc());
1919 
1920       if (llvm::Type* AdjTy =
1921           getTargetHooks().adjustInlineAsmType(*this, OutputConstraint,
1922                                                Arg->getType()))
1923         Arg = Builder.CreateBitCast(Arg, AdjTy);
1924 
1925       if (Info.allowsRegister())
1926         InOutConstraints += llvm::utostr(i);
1927       else
1928         InOutConstraints += OutputConstraint;
1929 
1930       InOutArgTypes.push_back(Arg->getType());
1931       InOutArgs.push_back(Arg);
1932     }
1933   }
1934 
1935   // If this is a Microsoft-style asm blob, store the return registers (EAX:EDX)
1936   // to the return value slot. Only do this when returning in registers.
1937   if (isa<MSAsmStmt>(&S)) {
1938     const ABIArgInfo &RetAI = CurFnInfo->getReturnInfo();
1939     if (RetAI.isDirect() || RetAI.isExtend()) {
1940       // Make a fake lvalue for the return value slot.
1941       LValue ReturnSlot = MakeAddrLValue(ReturnValue, FnRetTy);
1942       CGM.getTargetCodeGenInfo().addReturnRegisterOutputs(
1943           *this, ReturnSlot, Constraints, ResultRegTypes, ResultTruncRegTypes,
1944           ResultRegDests, AsmString, S.getNumOutputs());
1945       SawAsmBlock = true;
1946     }
1947   }
1948 
1949   for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) {
1950     const Expr *InputExpr = S.getInputExpr(i);
1951 
1952     TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
1953 
1954     if (Info.allowsMemory())
1955       ReadNone = false;
1956 
1957     if (!Constraints.empty())
1958       Constraints += ',';
1959 
1960     // Simplify the input constraint.
1961     std::string InputConstraint(S.getInputConstraint(i));
1962     InputConstraint = SimplifyConstraint(InputConstraint.c_str(), getTarget(),
1963                                          &OutputConstraintInfos);
1964 
1965     InputConstraint = AddVariableConstraints(
1966         InputConstraint, *InputExpr->IgnoreParenNoopCasts(getContext()),
1967         getTarget(), CGM, S, false /* No EarlyClobber */);
1968 
1969     llvm::Value *Arg = EmitAsmInput(Info, InputExpr, Constraints);
1970 
1971     // If this input argument is tied to a larger output result, extend the
1972     // input to be the same size as the output.  The LLVM backend wants to see
1973     // the input and output of a matching constraint be the same size.  Note
1974     // that GCC does not define what the top bits are here.  We use zext because
1975     // that is usually cheaper, but LLVM IR should really get an anyext someday.
1976     if (Info.hasTiedOperand()) {
1977       unsigned Output = Info.getTiedOperand();
1978       QualType OutputType = S.getOutputExpr(Output)->getType();
1979       QualType InputTy = InputExpr->getType();
1980 
1981       if (getContext().getTypeSize(OutputType) >
1982           getContext().getTypeSize(InputTy)) {
1983         // Use ptrtoint as appropriate so that we can do our extension.
1984         if (isa<llvm::PointerType>(Arg->getType()))
1985           Arg = Builder.CreatePtrToInt(Arg, IntPtrTy);
1986         llvm::Type *OutputTy = ConvertType(OutputType);
1987         if (isa<llvm::IntegerType>(OutputTy))
1988           Arg = Builder.CreateZExt(Arg, OutputTy);
1989         else if (isa<llvm::PointerType>(OutputTy))
1990           Arg = Builder.CreateZExt(Arg, IntPtrTy);
1991         else {
1992           assert(OutputTy->isFloatingPointTy() && "Unexpected output type");
1993           Arg = Builder.CreateFPExt(Arg, OutputTy);
1994         }
1995       }
1996     }
1997     if (llvm::Type* AdjTy =
1998               getTargetHooks().adjustInlineAsmType(*this, InputConstraint,
1999                                                    Arg->getType()))
2000       Arg = Builder.CreateBitCast(Arg, AdjTy);
2001     else
2002       CGM.getDiags().Report(S.getAsmLoc(), diag::err_asm_invalid_type_in_input)
2003           << InputExpr->getType() << InputConstraint;
2004 
2005     ArgTypes.push_back(Arg->getType());
2006     Args.push_back(Arg);
2007     Constraints += InputConstraint;
2008   }
2009 
2010   // Append the "input" part of inout constraints last.
2011   for (unsigned i = 0, e = InOutArgs.size(); i != e; i++) {
2012     ArgTypes.push_back(InOutArgTypes[i]);
2013     Args.push_back(InOutArgs[i]);
2014   }
2015   Constraints += InOutConstraints;
2016 
2017   // Clobbers
2018   for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) {
2019     StringRef Clobber = S.getClobber(i);
2020 
2021     if (Clobber == "memory")
2022       ReadOnly = ReadNone = false;
2023     else if (Clobber != "cc")
2024       Clobber = getTarget().getNormalizedGCCRegisterName(Clobber);
2025 
2026     if (!Constraints.empty())
2027       Constraints += ',';
2028 
2029     Constraints += "~{";
2030     Constraints += Clobber;
2031     Constraints += '}';
2032   }
2033 
2034   // Add machine specific clobbers
2035   std::string MachineClobbers = getTarget().getClobbers();
2036   if (!MachineClobbers.empty()) {
2037     if (!Constraints.empty())
2038       Constraints += ',';
2039     Constraints += MachineClobbers;
2040   }
2041 
2042   llvm::Type *ResultType;
2043   if (ResultRegTypes.empty())
2044     ResultType = VoidTy;
2045   else if (ResultRegTypes.size() == 1)
2046     ResultType = ResultRegTypes[0];
2047   else
2048     ResultType = llvm::StructType::get(getLLVMContext(), ResultRegTypes);
2049 
2050   llvm::FunctionType *FTy =
2051     llvm::FunctionType::get(ResultType, ArgTypes, false);
2052 
2053   bool HasSideEffect = S.isVolatile() || S.getNumOutputs() == 0;
2054   llvm::InlineAsm::AsmDialect AsmDialect = isa<MSAsmStmt>(&S) ?
2055     llvm::InlineAsm::AD_Intel : llvm::InlineAsm::AD_ATT;
2056   llvm::InlineAsm *IA =
2057     llvm::InlineAsm::get(FTy, AsmString, Constraints, HasSideEffect,
2058                          /* IsAlignStack */ false, AsmDialect);
2059   llvm::CallInst *Result = Builder.CreateCall(IA, Args);
2060   Result->addAttribute(llvm::AttributeSet::FunctionIndex,
2061                        llvm::Attribute::NoUnwind);
2062 
2063   if (isa<MSAsmStmt>(&S)) {
2064     // If the assembly contains any labels, mark the call noduplicate to prevent
2065     // defining the same ASM label twice (PR23715). This is pretty hacky, but it
2066     // works.
2067     if (AsmString.find("__MSASMLABEL_") != std::string::npos)
2068       Result->addAttribute(llvm::AttributeSet::FunctionIndex,
2069                            llvm::Attribute::NoDuplicate);
2070   }
2071 
2072   // Attach readnone and readonly attributes.
2073   if (!HasSideEffect) {
2074     if (ReadNone)
2075       Result->addAttribute(llvm::AttributeSet::FunctionIndex,
2076                            llvm::Attribute::ReadNone);
2077     else if (ReadOnly)
2078       Result->addAttribute(llvm::AttributeSet::FunctionIndex,
2079                            llvm::Attribute::ReadOnly);
2080   }
2081 
2082   // Slap the source location of the inline asm into a !srcloc metadata on the
2083   // call.
2084   if (const GCCAsmStmt *gccAsmStmt = dyn_cast<GCCAsmStmt>(&S)) {
2085     Result->setMetadata("srcloc", getAsmSrcLocInfo(gccAsmStmt->getAsmString(),
2086                                                    *this));
2087   } else {
2088     // At least put the line number on MS inline asm blobs.
2089     auto Loc = llvm::ConstantInt::get(Int32Ty, S.getAsmLoc().getRawEncoding());
2090     Result->setMetadata("srcloc",
2091                         llvm::MDNode::get(getLLVMContext(),
2092                                           llvm::ConstantAsMetadata::get(Loc)));
2093   }
2094 
2095   if (getLangOpts().CUDA && getLangOpts().CUDAIsDevice) {
2096     // Conservatively, mark all inline asm blocks in CUDA as convergent
2097     // (meaning, they may call an intrinsically convergent op, such as bar.sync,
2098     // and so can't have certain optimizations applied around them).
2099     Result->addAttribute(llvm::AttributeSet::FunctionIndex,
2100                          llvm::Attribute::Convergent);
2101   }
2102 
2103   // Extract all of the register value results from the asm.
2104   std::vector<llvm::Value*> RegResults;
2105   if (ResultRegTypes.size() == 1) {
2106     RegResults.push_back(Result);
2107   } else {
2108     for (unsigned i = 0, e = ResultRegTypes.size(); i != e; ++i) {
2109       llvm::Value *Tmp = Builder.CreateExtractValue(Result, i, "asmresult");
2110       RegResults.push_back(Tmp);
2111     }
2112   }
2113 
2114   assert(RegResults.size() == ResultRegTypes.size());
2115   assert(RegResults.size() == ResultTruncRegTypes.size());
2116   assert(RegResults.size() == ResultRegDests.size());
2117   for (unsigned i = 0, e = RegResults.size(); i != e; ++i) {
2118     llvm::Value *Tmp = RegResults[i];
2119 
2120     // If the result type of the LLVM IR asm doesn't match the result type of
2121     // the expression, do the conversion.
2122     if (ResultRegTypes[i] != ResultTruncRegTypes[i]) {
2123       llvm::Type *TruncTy = ResultTruncRegTypes[i];
2124 
2125       // Truncate the integer result to the right size, note that TruncTy can be
2126       // a pointer.
2127       if (TruncTy->isFloatingPointTy())
2128         Tmp = Builder.CreateFPTrunc(Tmp, TruncTy);
2129       else if (TruncTy->isPointerTy() && Tmp->getType()->isIntegerTy()) {
2130         uint64_t ResSize = CGM.getDataLayout().getTypeSizeInBits(TruncTy);
2131         Tmp = Builder.CreateTrunc(Tmp,
2132                    llvm::IntegerType::get(getLLVMContext(), (unsigned)ResSize));
2133         Tmp = Builder.CreateIntToPtr(Tmp, TruncTy);
2134       } else if (Tmp->getType()->isPointerTy() && TruncTy->isIntegerTy()) {
2135         uint64_t TmpSize =CGM.getDataLayout().getTypeSizeInBits(Tmp->getType());
2136         Tmp = Builder.CreatePtrToInt(Tmp,
2137                    llvm::IntegerType::get(getLLVMContext(), (unsigned)TmpSize));
2138         Tmp = Builder.CreateTrunc(Tmp, TruncTy);
2139       } else if (TruncTy->isIntegerTy()) {
2140         Tmp = Builder.CreateTrunc(Tmp, TruncTy);
2141       } else if (TruncTy->isVectorTy()) {
2142         Tmp = Builder.CreateBitCast(Tmp, TruncTy);
2143       }
2144     }
2145 
2146     EmitStoreThroughLValue(RValue::get(Tmp), ResultRegDests[i]);
2147   }
2148 }
2149 
InitCapturedStruct(const CapturedStmt & S)2150 LValue CodeGenFunction::InitCapturedStruct(const CapturedStmt &S) {
2151   const RecordDecl *RD = S.getCapturedRecordDecl();
2152   QualType RecordTy = getContext().getRecordType(RD);
2153 
2154   // Initialize the captured struct.
2155   LValue SlotLV =
2156     MakeAddrLValue(CreateMemTemp(RecordTy, "agg.captured"), RecordTy);
2157 
2158   RecordDecl::field_iterator CurField = RD->field_begin();
2159   for (CapturedStmt::const_capture_init_iterator I = S.capture_init_begin(),
2160                                                  E = S.capture_init_end();
2161        I != E; ++I, ++CurField) {
2162     LValue LV = EmitLValueForFieldInitialization(SlotLV, *CurField);
2163     if (CurField->hasCapturedVLAType()) {
2164       auto VAT = CurField->getCapturedVLAType();
2165       EmitStoreThroughLValue(RValue::get(VLASizeMap[VAT->getSizeExpr()]), LV);
2166     } else {
2167       EmitInitializerForField(*CurField, LV, *I, None);
2168     }
2169   }
2170 
2171   return SlotLV;
2172 }
2173 
2174 /// Generate an outlined function for the body of a CapturedStmt, store any
2175 /// captured variables into the captured struct, and call the outlined function.
2176 llvm::Function *
EmitCapturedStmt(const CapturedStmt & S,CapturedRegionKind K)2177 CodeGenFunction::EmitCapturedStmt(const CapturedStmt &S, CapturedRegionKind K) {
2178   LValue CapStruct = InitCapturedStruct(S);
2179 
2180   // Emit the CapturedDecl
2181   CodeGenFunction CGF(CGM, true);
2182   CGCapturedStmtRAII CapInfoRAII(CGF, new CGCapturedStmtInfo(S, K));
2183   llvm::Function *F = CGF.GenerateCapturedStmtFunction(S);
2184   delete CGF.CapturedStmtInfo;
2185 
2186   // Emit call to the helper function.
2187   EmitCallOrInvoke(F, CapStruct.getPointer());
2188 
2189   return F;
2190 }
2191 
GenerateCapturedStmtArgument(const CapturedStmt & S)2192 Address CodeGenFunction::GenerateCapturedStmtArgument(const CapturedStmt &S) {
2193   LValue CapStruct = InitCapturedStruct(S);
2194   return CapStruct.getAddress();
2195 }
2196 
2197 /// Creates the outlined function for a CapturedStmt.
2198 llvm::Function *
GenerateCapturedStmtFunction(const CapturedStmt & S)2199 CodeGenFunction::GenerateCapturedStmtFunction(const CapturedStmt &S) {
2200   assert(CapturedStmtInfo &&
2201     "CapturedStmtInfo should be set when generating the captured function");
2202   const CapturedDecl *CD = S.getCapturedDecl();
2203   const RecordDecl *RD = S.getCapturedRecordDecl();
2204   SourceLocation Loc = S.getLocStart();
2205   assert(CD->hasBody() && "missing CapturedDecl body");
2206 
2207   // Build the argument list.
2208   ASTContext &Ctx = CGM.getContext();
2209   FunctionArgList Args;
2210   Args.append(CD->param_begin(), CD->param_end());
2211 
2212   // Create the function declaration.
2213   FunctionType::ExtInfo ExtInfo;
2214   const CGFunctionInfo &FuncInfo =
2215     CGM.getTypes().arrangeBuiltinFunctionDeclaration(Ctx.VoidTy, Args);
2216   llvm::FunctionType *FuncLLVMTy = CGM.getTypes().GetFunctionType(FuncInfo);
2217 
2218   llvm::Function *F =
2219     llvm::Function::Create(FuncLLVMTy, llvm::GlobalValue::InternalLinkage,
2220                            CapturedStmtInfo->getHelperName(), &CGM.getModule());
2221   CGM.SetInternalFunctionAttributes(CD, F, FuncInfo);
2222   if (CD->isNothrow())
2223     F->addFnAttr(llvm::Attribute::NoUnwind);
2224 
2225   // Generate the function.
2226   StartFunction(CD, Ctx.VoidTy, F, FuncInfo, Args,
2227                 CD->getLocation(),
2228                 CD->getBody()->getLocStart());
2229   // Set the context parameter in CapturedStmtInfo.
2230   Address DeclPtr = GetAddrOfLocalVar(CD->getContextParam());
2231   CapturedStmtInfo->setContextValue(Builder.CreateLoad(DeclPtr));
2232 
2233   // Initialize variable-length arrays.
2234   LValue Base = MakeNaturalAlignAddrLValue(CapturedStmtInfo->getContextValue(),
2235                                            Ctx.getTagDeclType(RD));
2236   for (auto *FD : RD->fields()) {
2237     if (FD->hasCapturedVLAType()) {
2238       auto *ExprArg = EmitLoadOfLValue(EmitLValueForField(Base, FD),
2239                                        S.getLocStart()).getScalarVal();
2240       auto VAT = FD->getCapturedVLAType();
2241       VLASizeMap[VAT->getSizeExpr()] = ExprArg;
2242     }
2243   }
2244 
2245   // If 'this' is captured, load it into CXXThisValue.
2246   if (CapturedStmtInfo->isCXXThisExprCaptured()) {
2247     FieldDecl *FD = CapturedStmtInfo->getThisFieldDecl();
2248     LValue ThisLValue = EmitLValueForField(Base, FD);
2249     CXXThisValue = EmitLoadOfLValue(ThisLValue, Loc).getScalarVal();
2250   }
2251 
2252   PGO.assignRegionCounters(GlobalDecl(CD), F);
2253   CapturedStmtInfo->EmitBody(*this, CD->getBody());
2254   FinishFunction(CD->getBodyRBrace());
2255 
2256   return F;
2257 }
2258