1 //===--- CGStmt.cpp - Emit LLVM Code from Statements ----------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This contains code to emit Stmt nodes as LLVM code.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "CodeGenFunction.h"
14 #include "CGDebugInfo.h"
15 #include "CodeGenModule.h"
16 #include "TargetInfo.h"
17 #include "clang/AST/StmtVisitor.h"
18 #include "clang/Basic/Builtins.h"
19 #include "clang/Basic/PrettyStackTrace.h"
20 #include "clang/Basic/TargetInfo.h"
21 #include "llvm/ADT/StringExtras.h"
22 #include "llvm/IR/DataLayout.h"
23 #include "llvm/IR/InlineAsm.h"
24 #include "llvm/IR/Intrinsics.h"
25 #include "llvm/IR/MDBuilder.h"
26 
27 using namespace clang;
28 using namespace CodeGen;
29 
30 //===----------------------------------------------------------------------===//
31 //                              Statement Emission
32 //===----------------------------------------------------------------------===//
33 
34 void CodeGenFunction::EmitStopPoint(const Stmt *S) {
35   if (CGDebugInfo *DI = getDebugInfo()) {
36     SourceLocation Loc;
37     Loc = S->getBeginLoc();
38     DI->EmitLocation(Builder, Loc);
39 
40     LastStopPoint = Loc;
41   }
42 }
43 
44 void CodeGenFunction::EmitStmt(const Stmt *S, ArrayRef<const Attr *> Attrs) {
45   assert(S && "Null statement?");
46   PGO.setCurrentStmt(S);
47 
48   // These statements have their own debug info handling.
49   if (EmitSimpleStmt(S))
50     return;
51 
52   // Check if we are generating unreachable code.
53   if (!HaveInsertPoint()) {
54     // If so, and the statement doesn't contain a label, then we do not need to
55     // generate actual code. This is safe because (1) the current point is
56     // unreachable, so we don't need to execute the code, and (2) we've already
57     // handled the statements which update internal data structures (like the
58     // local variable map) which could be used by subsequent statements.
59     if (!ContainsLabel(S)) {
60       // Verify that any decl statements were handled as simple, they may be in
61       // scope of subsequent reachable statements.
62       assert(!isa<DeclStmt>(*S) && "Unexpected DeclStmt!");
63       return;
64     }
65 
66     // Otherwise, make a new block to hold the code.
67     EnsureInsertPoint();
68   }
69 
70   // Generate a stoppoint if we are emitting debug info.
71   EmitStopPoint(S);
72 
73   // Ignore all OpenMP directives except for simd if OpenMP with Simd is
74   // enabled.
75   if (getLangOpts().OpenMP && getLangOpts().OpenMPSimd) {
76     if (const auto *D = dyn_cast<OMPExecutableDirective>(S)) {
77       EmitSimpleOMPExecutableDirective(*D);
78       return;
79     }
80   }
81 
82   switch (S->getStmtClass()) {
83   case Stmt::NoStmtClass:
84   case Stmt::CXXCatchStmtClass:
85   case Stmt::SEHExceptStmtClass:
86   case Stmt::SEHFinallyStmtClass:
87   case Stmt::MSDependentExistsStmtClass:
88     llvm_unreachable("invalid statement class to emit generically");
89   case Stmt::NullStmtClass:
90   case Stmt::CompoundStmtClass:
91   case Stmt::DeclStmtClass:
92   case Stmt::LabelStmtClass:
93   case Stmt::AttributedStmtClass:
94   case Stmt::GotoStmtClass:
95   case Stmt::BreakStmtClass:
96   case Stmt::ContinueStmtClass:
97   case Stmt::DefaultStmtClass:
98   case Stmt::CaseStmtClass:
99   case Stmt::SEHLeaveStmtClass:
100     llvm_unreachable("should have emitted these statements as simple");
101 
102 #define STMT(Type, Base)
103 #define ABSTRACT_STMT(Op)
104 #define EXPR(Type, Base) \
105   case Stmt::Type##Class:
106 #include "clang/AST/StmtNodes.inc"
107   {
108     // Remember the block we came in on.
109     llvm::BasicBlock *incoming = Builder.GetInsertBlock();
110     assert(incoming && "expression emission must have an insertion point");
111 
112     EmitIgnoredExpr(cast<Expr>(S));
113 
114     llvm::BasicBlock *outgoing = Builder.GetInsertBlock();
115     assert(outgoing && "expression emission cleared block!");
116 
117     // The expression emitters assume (reasonably!) that the insertion
118     // point is always set.  To maintain that, the call-emission code
119     // for noreturn functions has to enter a new block with no
120     // predecessors.  We want to kill that block and mark the current
121     // insertion point unreachable in the common case of a call like
122     // "exit();".  Since expression emission doesn't otherwise create
123     // blocks with no predecessors, we can just test for that.
124     // However, we must be careful not to do this to our incoming
125     // block, because *statement* emission does sometimes create
126     // reachable blocks which will have no predecessors until later in
127     // the function.  This occurs with, e.g., labels that are not
128     // reachable by fallthrough.
129     if (incoming != outgoing && outgoing->use_empty()) {
130       outgoing->eraseFromParent();
131       Builder.ClearInsertionPoint();
132     }
133     break;
134   }
135 
136   case Stmt::IndirectGotoStmtClass:
137     EmitIndirectGotoStmt(cast<IndirectGotoStmt>(*S)); break;
138 
139   case Stmt::IfStmtClass:      EmitIfStmt(cast<IfStmt>(*S));              break;
140   case Stmt::WhileStmtClass:   EmitWhileStmt(cast<WhileStmt>(*S), Attrs); break;
141   case Stmt::DoStmtClass:      EmitDoStmt(cast<DoStmt>(*S), Attrs);       break;
142   case Stmt::ForStmtClass:     EmitForStmt(cast<ForStmt>(*S), Attrs);     break;
143 
144   case Stmt::ReturnStmtClass:  EmitReturnStmt(cast<ReturnStmt>(*S));      break;
145 
146   case Stmt::SwitchStmtClass:  EmitSwitchStmt(cast<SwitchStmt>(*S));      break;
147   case Stmt::GCCAsmStmtClass:  // Intentional fall-through.
148   case Stmt::MSAsmStmtClass:   EmitAsmStmt(cast<AsmStmt>(*S));            break;
149   case Stmt::CoroutineBodyStmtClass:
150     EmitCoroutineBody(cast<CoroutineBodyStmt>(*S));
151     break;
152   case Stmt::CoreturnStmtClass:
153     EmitCoreturnStmt(cast<CoreturnStmt>(*S));
154     break;
155   case Stmt::CapturedStmtClass: {
156     const CapturedStmt *CS = cast<CapturedStmt>(S);
157     EmitCapturedStmt(*CS, CS->getCapturedRegionKind());
158     }
159     break;
160   case Stmt::ObjCAtTryStmtClass:
161     EmitObjCAtTryStmt(cast<ObjCAtTryStmt>(*S));
162     break;
163   case Stmt::ObjCAtCatchStmtClass:
164     llvm_unreachable(
165                     "@catch statements should be handled by EmitObjCAtTryStmt");
166   case Stmt::ObjCAtFinallyStmtClass:
167     llvm_unreachable(
168                   "@finally statements should be handled by EmitObjCAtTryStmt");
169   case Stmt::ObjCAtThrowStmtClass:
170     EmitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(*S));
171     break;
172   case Stmt::ObjCAtSynchronizedStmtClass:
173     EmitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(*S));
174     break;
175   case Stmt::ObjCForCollectionStmtClass:
176     EmitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(*S));
177     break;
178   case Stmt::ObjCAutoreleasePoolStmtClass:
179     EmitObjCAutoreleasePoolStmt(cast<ObjCAutoreleasePoolStmt>(*S));
180     break;
181 
182   case Stmt::CXXTryStmtClass:
183     EmitCXXTryStmt(cast<CXXTryStmt>(*S));
184     break;
185   case Stmt::CXXForRangeStmtClass:
186     EmitCXXForRangeStmt(cast<CXXForRangeStmt>(*S), Attrs);
187     break;
188   case Stmt::SEHTryStmtClass:
189     EmitSEHTryStmt(cast<SEHTryStmt>(*S));
190     break;
191   case Stmt::OMPParallelDirectiveClass:
192     EmitOMPParallelDirective(cast<OMPParallelDirective>(*S));
193     break;
194   case Stmt::OMPSimdDirectiveClass:
195     EmitOMPSimdDirective(cast<OMPSimdDirective>(*S));
196     break;
197   case Stmt::OMPForDirectiveClass:
198     EmitOMPForDirective(cast<OMPForDirective>(*S));
199     break;
200   case Stmt::OMPForSimdDirectiveClass:
201     EmitOMPForSimdDirective(cast<OMPForSimdDirective>(*S));
202     break;
203   case Stmt::OMPSectionsDirectiveClass:
204     EmitOMPSectionsDirective(cast<OMPSectionsDirective>(*S));
205     break;
206   case Stmt::OMPSectionDirectiveClass:
207     EmitOMPSectionDirective(cast<OMPSectionDirective>(*S));
208     break;
209   case Stmt::OMPSingleDirectiveClass:
210     EmitOMPSingleDirective(cast<OMPSingleDirective>(*S));
211     break;
212   case Stmt::OMPMasterDirectiveClass:
213     EmitOMPMasterDirective(cast<OMPMasterDirective>(*S));
214     break;
215   case Stmt::OMPCriticalDirectiveClass:
216     EmitOMPCriticalDirective(cast<OMPCriticalDirective>(*S));
217     break;
218   case Stmt::OMPParallelForDirectiveClass:
219     EmitOMPParallelForDirective(cast<OMPParallelForDirective>(*S));
220     break;
221   case Stmt::OMPParallelForSimdDirectiveClass:
222     EmitOMPParallelForSimdDirective(cast<OMPParallelForSimdDirective>(*S));
223     break;
224   case Stmt::OMPParallelSectionsDirectiveClass:
225     EmitOMPParallelSectionsDirective(cast<OMPParallelSectionsDirective>(*S));
226     break;
227   case Stmt::OMPTaskDirectiveClass:
228     EmitOMPTaskDirective(cast<OMPTaskDirective>(*S));
229     break;
230   case Stmt::OMPTaskyieldDirectiveClass:
231     EmitOMPTaskyieldDirective(cast<OMPTaskyieldDirective>(*S));
232     break;
233   case Stmt::OMPBarrierDirectiveClass:
234     EmitOMPBarrierDirective(cast<OMPBarrierDirective>(*S));
235     break;
236   case Stmt::OMPTaskwaitDirectiveClass:
237     EmitOMPTaskwaitDirective(cast<OMPTaskwaitDirective>(*S));
238     break;
239   case Stmt::OMPTaskgroupDirectiveClass:
240     EmitOMPTaskgroupDirective(cast<OMPTaskgroupDirective>(*S));
241     break;
242   case Stmt::OMPFlushDirectiveClass:
243     EmitOMPFlushDirective(cast<OMPFlushDirective>(*S));
244     break;
245   case Stmt::OMPOrderedDirectiveClass:
246     EmitOMPOrderedDirective(cast<OMPOrderedDirective>(*S));
247     break;
248   case Stmt::OMPAtomicDirectiveClass:
249     EmitOMPAtomicDirective(cast<OMPAtomicDirective>(*S));
250     break;
251   case Stmt::OMPTargetDirectiveClass:
252     EmitOMPTargetDirective(cast<OMPTargetDirective>(*S));
253     break;
254   case Stmt::OMPTeamsDirectiveClass:
255     EmitOMPTeamsDirective(cast<OMPTeamsDirective>(*S));
256     break;
257   case Stmt::OMPCancellationPointDirectiveClass:
258     EmitOMPCancellationPointDirective(cast<OMPCancellationPointDirective>(*S));
259     break;
260   case Stmt::OMPCancelDirectiveClass:
261     EmitOMPCancelDirective(cast<OMPCancelDirective>(*S));
262     break;
263   case Stmt::OMPTargetDataDirectiveClass:
264     EmitOMPTargetDataDirective(cast<OMPTargetDataDirective>(*S));
265     break;
266   case Stmt::OMPTargetEnterDataDirectiveClass:
267     EmitOMPTargetEnterDataDirective(cast<OMPTargetEnterDataDirective>(*S));
268     break;
269   case Stmt::OMPTargetExitDataDirectiveClass:
270     EmitOMPTargetExitDataDirective(cast<OMPTargetExitDataDirective>(*S));
271     break;
272   case Stmt::OMPTargetParallelDirectiveClass:
273     EmitOMPTargetParallelDirective(cast<OMPTargetParallelDirective>(*S));
274     break;
275   case Stmt::OMPTargetParallelForDirectiveClass:
276     EmitOMPTargetParallelForDirective(cast<OMPTargetParallelForDirective>(*S));
277     break;
278   case Stmt::OMPTaskLoopDirectiveClass:
279     EmitOMPTaskLoopDirective(cast<OMPTaskLoopDirective>(*S));
280     break;
281   case Stmt::OMPTaskLoopSimdDirectiveClass:
282     EmitOMPTaskLoopSimdDirective(cast<OMPTaskLoopSimdDirective>(*S));
283     break;
284   case Stmt::OMPMasterTaskLoopDirectiveClass:
285     EmitOMPMasterTaskLoopDirective(cast<OMPMasterTaskLoopDirective>(*S));
286     break;
287   case Stmt::OMPParallelMasterTaskLoopDirectiveClass:
288     EmitOMPParallelMasterTaskLoopDirective(
289         cast<OMPParallelMasterTaskLoopDirective>(*S));
290     break;
291   case Stmt::OMPDistributeDirectiveClass:
292     EmitOMPDistributeDirective(cast<OMPDistributeDirective>(*S));
293     break;
294   case Stmt::OMPTargetUpdateDirectiveClass:
295     EmitOMPTargetUpdateDirective(cast<OMPTargetUpdateDirective>(*S));
296     break;
297   case Stmt::OMPDistributeParallelForDirectiveClass:
298     EmitOMPDistributeParallelForDirective(
299         cast<OMPDistributeParallelForDirective>(*S));
300     break;
301   case Stmt::OMPDistributeParallelForSimdDirectiveClass:
302     EmitOMPDistributeParallelForSimdDirective(
303         cast<OMPDistributeParallelForSimdDirective>(*S));
304     break;
305   case Stmt::OMPDistributeSimdDirectiveClass:
306     EmitOMPDistributeSimdDirective(cast<OMPDistributeSimdDirective>(*S));
307     break;
308   case Stmt::OMPTargetParallelForSimdDirectiveClass:
309     EmitOMPTargetParallelForSimdDirective(
310         cast<OMPTargetParallelForSimdDirective>(*S));
311     break;
312   case Stmt::OMPTargetSimdDirectiveClass:
313     EmitOMPTargetSimdDirective(cast<OMPTargetSimdDirective>(*S));
314     break;
315   case Stmt::OMPTeamsDistributeDirectiveClass:
316     EmitOMPTeamsDistributeDirective(cast<OMPTeamsDistributeDirective>(*S));
317     break;
318   case Stmt::OMPTeamsDistributeSimdDirectiveClass:
319     EmitOMPTeamsDistributeSimdDirective(
320         cast<OMPTeamsDistributeSimdDirective>(*S));
321     break;
322   case Stmt::OMPTeamsDistributeParallelForSimdDirectiveClass:
323     EmitOMPTeamsDistributeParallelForSimdDirective(
324         cast<OMPTeamsDistributeParallelForSimdDirective>(*S));
325     break;
326   case Stmt::OMPTeamsDistributeParallelForDirectiveClass:
327     EmitOMPTeamsDistributeParallelForDirective(
328         cast<OMPTeamsDistributeParallelForDirective>(*S));
329     break;
330   case Stmt::OMPTargetTeamsDirectiveClass:
331     EmitOMPTargetTeamsDirective(cast<OMPTargetTeamsDirective>(*S));
332     break;
333   case Stmt::OMPTargetTeamsDistributeDirectiveClass:
334     EmitOMPTargetTeamsDistributeDirective(
335         cast<OMPTargetTeamsDistributeDirective>(*S));
336     break;
337   case Stmt::OMPTargetTeamsDistributeParallelForDirectiveClass:
338     EmitOMPTargetTeamsDistributeParallelForDirective(
339         cast<OMPTargetTeamsDistributeParallelForDirective>(*S));
340     break;
341   case Stmt::OMPTargetTeamsDistributeParallelForSimdDirectiveClass:
342     EmitOMPTargetTeamsDistributeParallelForSimdDirective(
343         cast<OMPTargetTeamsDistributeParallelForSimdDirective>(*S));
344     break;
345   case Stmt::OMPTargetTeamsDistributeSimdDirectiveClass:
346     EmitOMPTargetTeamsDistributeSimdDirective(
347         cast<OMPTargetTeamsDistributeSimdDirective>(*S));
348     break;
349   }
350 }
351 
352 bool CodeGenFunction::EmitSimpleStmt(const Stmt *S) {
353   switch (S->getStmtClass()) {
354   default: return false;
355   case Stmt::NullStmtClass: break;
356   case Stmt::CompoundStmtClass: EmitCompoundStmt(cast<CompoundStmt>(*S)); break;
357   case Stmt::DeclStmtClass:     EmitDeclStmt(cast<DeclStmt>(*S));         break;
358   case Stmt::LabelStmtClass:    EmitLabelStmt(cast<LabelStmt>(*S));       break;
359   case Stmt::AttributedStmtClass:
360                             EmitAttributedStmt(cast<AttributedStmt>(*S)); break;
361   case Stmt::GotoStmtClass:     EmitGotoStmt(cast<GotoStmt>(*S));         break;
362   case Stmt::BreakStmtClass:    EmitBreakStmt(cast<BreakStmt>(*S));       break;
363   case Stmt::ContinueStmtClass: EmitContinueStmt(cast<ContinueStmt>(*S)); break;
364   case Stmt::DefaultStmtClass:  EmitDefaultStmt(cast<DefaultStmt>(*S));   break;
365   case Stmt::CaseStmtClass:     EmitCaseStmt(cast<CaseStmt>(*S));         break;
366   case Stmt::SEHLeaveStmtClass: EmitSEHLeaveStmt(cast<SEHLeaveStmt>(*S)); break;
367   }
368 
369   return true;
370 }
371 
372 /// EmitCompoundStmt - Emit a compound statement {..} node.  If GetLast is true,
373 /// this captures the expression result of the last sub-statement and returns it
374 /// (for use by the statement expression extension).
375 Address CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast,
376                                           AggValueSlot AggSlot) {
377   PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),S.getLBracLoc(),
378                              "LLVM IR generation of compound statement ('{}')");
379 
380   // Keep track of the current cleanup stack depth, including debug scopes.
381   LexicalScope Scope(*this, S.getSourceRange());
382 
383   return EmitCompoundStmtWithoutScope(S, GetLast, AggSlot);
384 }
385 
386 Address
387 CodeGenFunction::EmitCompoundStmtWithoutScope(const CompoundStmt &S,
388                                               bool GetLast,
389                                               AggValueSlot AggSlot) {
390 
391   const Stmt *ExprResult = S.getStmtExprResult();
392   assert((!GetLast || (GetLast && ExprResult)) &&
393          "If GetLast is true then the CompoundStmt must have a StmtExprResult");
394 
395   Address RetAlloca = Address::invalid();
396 
397   for (auto *CurStmt : S.body()) {
398     if (GetLast && ExprResult == CurStmt) {
399       // We have to special case labels here.  They are statements, but when put
400       // at the end of a statement expression, they yield the value of their
401       // subexpression.  Handle this by walking through all labels we encounter,
402       // emitting them before we evaluate the subexpr.
403       // Similar issues arise for attributed statements.
404       while (!isa<Expr>(ExprResult)) {
405         if (const auto *LS = dyn_cast<LabelStmt>(ExprResult)) {
406           EmitLabel(LS->getDecl());
407           ExprResult = LS->getSubStmt();
408         } else if (const auto *AS = dyn_cast<AttributedStmt>(ExprResult)) {
409           // FIXME: Update this if we ever have attributes that affect the
410           // semantics of an expression.
411           ExprResult = AS->getSubStmt();
412         } else {
413           llvm_unreachable("unknown value statement");
414         }
415       }
416 
417       EnsureInsertPoint();
418 
419       const Expr *E = cast<Expr>(ExprResult);
420       QualType ExprTy = E->getType();
421       if (hasAggregateEvaluationKind(ExprTy)) {
422         EmitAggExpr(E, AggSlot);
423       } else {
424         // We can't return an RValue here because there might be cleanups at
425         // the end of the StmtExpr.  Because of that, we have to emit the result
426         // here into a temporary alloca.
427         RetAlloca = CreateMemTemp(ExprTy);
428         EmitAnyExprToMem(E, RetAlloca, Qualifiers(),
429                          /*IsInit*/ false);
430       }
431     } else {
432       EmitStmt(CurStmt);
433     }
434   }
435 
436   return RetAlloca;
437 }
438 
439 void CodeGenFunction::SimplifyForwardingBlocks(llvm::BasicBlock *BB) {
440   llvm::BranchInst *BI = dyn_cast<llvm::BranchInst>(BB->getTerminator());
441 
442   // If there is a cleanup stack, then we it isn't worth trying to
443   // simplify this block (we would need to remove it from the scope map
444   // and cleanup entry).
445   if (!EHStack.empty())
446     return;
447 
448   // Can only simplify direct branches.
449   if (!BI || !BI->isUnconditional())
450     return;
451 
452   // Can only simplify empty blocks.
453   if (BI->getIterator() != BB->begin())
454     return;
455 
456   BB->replaceAllUsesWith(BI->getSuccessor(0));
457   BI->eraseFromParent();
458   BB->eraseFromParent();
459 }
460 
461 void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) {
462   llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
463 
464   // Fall out of the current block (if necessary).
465   EmitBranch(BB);
466 
467   if (IsFinished && BB->use_empty()) {
468     delete BB;
469     return;
470   }
471 
472   // Place the block after the current block, if possible, or else at
473   // the end of the function.
474   if (CurBB && CurBB->getParent())
475     CurFn->getBasicBlockList().insertAfter(CurBB->getIterator(), BB);
476   else
477     CurFn->getBasicBlockList().push_back(BB);
478   Builder.SetInsertPoint(BB);
479 }
480 
481 void CodeGenFunction::EmitBranch(llvm::BasicBlock *Target) {
482   // Emit a branch from the current block to the target one if this
483   // was a real block.  If this was just a fall-through block after a
484   // terminator, don't emit it.
485   llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
486 
487   if (!CurBB || CurBB->getTerminator()) {
488     // If there is no insert point or the previous block is already
489     // terminated, don't touch it.
490   } else {
491     // Otherwise, create a fall-through branch.
492     Builder.CreateBr(Target);
493   }
494 
495   Builder.ClearInsertionPoint();
496 }
497 
498 void CodeGenFunction::EmitBlockAfterUses(llvm::BasicBlock *block) {
499   bool inserted = false;
500   for (llvm::User *u : block->users()) {
501     if (llvm::Instruction *insn = dyn_cast<llvm::Instruction>(u)) {
502       CurFn->getBasicBlockList().insertAfter(insn->getParent()->getIterator(),
503                                              block);
504       inserted = true;
505       break;
506     }
507   }
508 
509   if (!inserted)
510     CurFn->getBasicBlockList().push_back(block);
511 
512   Builder.SetInsertPoint(block);
513 }
514 
515 CodeGenFunction::JumpDest
516 CodeGenFunction::getJumpDestForLabel(const LabelDecl *D) {
517   JumpDest &Dest = LabelMap[D];
518   if (Dest.isValid()) return Dest;
519 
520   // Create, but don't insert, the new block.
521   Dest = JumpDest(createBasicBlock(D->getName()),
522                   EHScopeStack::stable_iterator::invalid(),
523                   NextCleanupDestIndex++);
524   return Dest;
525 }
526 
527 void CodeGenFunction::EmitLabel(const LabelDecl *D) {
528   // Add this label to the current lexical scope if we're within any
529   // normal cleanups.  Jumps "in" to this label --- when permitted by
530   // the language --- may need to be routed around such cleanups.
531   if (EHStack.hasNormalCleanups() && CurLexicalScope)
532     CurLexicalScope->addLabel(D);
533 
534   JumpDest &Dest = LabelMap[D];
535 
536   // If we didn't need a forward reference to this label, just go
537   // ahead and create a destination at the current scope.
538   if (!Dest.isValid()) {
539     Dest = getJumpDestInCurrentScope(D->getName());
540 
541   // Otherwise, we need to give this label a target depth and remove
542   // it from the branch-fixups list.
543   } else {
544     assert(!Dest.getScopeDepth().isValid() && "already emitted label!");
545     Dest.setScopeDepth(EHStack.stable_begin());
546     ResolveBranchFixups(Dest.getBlock());
547   }
548 
549   EmitBlock(Dest.getBlock());
550 
551   // Emit debug info for labels.
552   if (CGDebugInfo *DI = getDebugInfo()) {
553     if (CGM.getCodeGenOpts().getDebugInfo() >=
554         codegenoptions::LimitedDebugInfo) {
555       DI->setLocation(D->getLocation());
556       DI->EmitLabel(D, Builder);
557     }
558   }
559 
560   incrementProfileCounter(D->getStmt());
561 }
562 
563 /// Change the cleanup scope of the labels in this lexical scope to
564 /// match the scope of the enclosing context.
565 void CodeGenFunction::LexicalScope::rescopeLabels() {
566   assert(!Labels.empty());
567   EHScopeStack::stable_iterator innermostScope
568     = CGF.EHStack.getInnermostNormalCleanup();
569 
570   // Change the scope depth of all the labels.
571   for (SmallVectorImpl<const LabelDecl*>::const_iterator
572          i = Labels.begin(), e = Labels.end(); i != e; ++i) {
573     assert(CGF.LabelMap.count(*i));
574     JumpDest &dest = CGF.LabelMap.find(*i)->second;
575     assert(dest.getScopeDepth().isValid());
576     assert(innermostScope.encloses(dest.getScopeDepth()));
577     dest.setScopeDepth(innermostScope);
578   }
579 
580   // Reparent the labels if the new scope also has cleanups.
581   if (innermostScope != EHScopeStack::stable_end() && ParentScope) {
582     ParentScope->Labels.append(Labels.begin(), Labels.end());
583   }
584 }
585 
586 
587 void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) {
588   EmitLabel(S.getDecl());
589   EmitStmt(S.getSubStmt());
590 }
591 
592 void CodeGenFunction::EmitAttributedStmt(const AttributedStmt &S) {
593   EmitStmt(S.getSubStmt(), S.getAttrs());
594 }
595 
596 void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) {
597   // If this code is reachable then emit a stop point (if generating
598   // debug info). We have to do this ourselves because we are on the
599   // "simple" statement path.
600   if (HaveInsertPoint())
601     EmitStopPoint(&S);
602 
603   EmitBranchThroughCleanup(getJumpDestForLabel(S.getLabel()));
604 }
605 
606 
607 void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) {
608   if (const LabelDecl *Target = S.getConstantTarget()) {
609     EmitBranchThroughCleanup(getJumpDestForLabel(Target));
610     return;
611   }
612 
613   // Ensure that we have an i8* for our PHI node.
614   llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()),
615                                          Int8PtrTy, "addr");
616   llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
617 
618   // Get the basic block for the indirect goto.
619   llvm::BasicBlock *IndGotoBB = GetIndirectGotoBlock();
620 
621   // The first instruction in the block has to be the PHI for the switch dest,
622   // add an entry for this branch.
623   cast<llvm::PHINode>(IndGotoBB->begin())->addIncoming(V, CurBB);
624 
625   EmitBranch(IndGotoBB);
626 }
627 
628 void CodeGenFunction::EmitIfStmt(const IfStmt &S) {
629   // C99 6.8.4.1: The first substatement is executed if the expression compares
630   // unequal to 0.  The condition must be a scalar type.
631   LexicalScope ConditionScope(*this, S.getCond()->getSourceRange());
632 
633   if (S.getInit())
634     EmitStmt(S.getInit());
635 
636   if (S.getConditionVariable())
637     EmitDecl(*S.getConditionVariable());
638 
639   // If the condition constant folds and can be elided, try to avoid emitting
640   // the condition and the dead arm of the if/else.
641   bool CondConstant;
642   if (ConstantFoldsToSimpleInteger(S.getCond(), CondConstant,
643                                    S.isConstexpr())) {
644     // Figure out which block (then or else) is executed.
645     const Stmt *Executed = S.getThen();
646     const Stmt *Skipped  = S.getElse();
647     if (!CondConstant)  // Condition false?
648       std::swap(Executed, Skipped);
649 
650     // If the skipped block has no labels in it, just emit the executed block.
651     // This avoids emitting dead code and simplifies the CFG substantially.
652     if (S.isConstexpr() || !ContainsLabel(Skipped)) {
653       if (CondConstant)
654         incrementProfileCounter(&S);
655       if (Executed) {
656         RunCleanupsScope ExecutedScope(*this);
657         EmitStmt(Executed);
658       }
659       return;
660     }
661   }
662 
663   // Otherwise, the condition did not fold, or we couldn't elide it.  Just emit
664   // the conditional branch.
665   llvm::BasicBlock *ThenBlock = createBasicBlock("if.then");
666   llvm::BasicBlock *ContBlock = createBasicBlock("if.end");
667   llvm::BasicBlock *ElseBlock = ContBlock;
668   if (S.getElse())
669     ElseBlock = createBasicBlock("if.else");
670 
671   EmitBranchOnBoolExpr(S.getCond(), ThenBlock, ElseBlock,
672                        getProfileCount(S.getThen()));
673 
674   // Emit the 'then' code.
675   EmitBlock(ThenBlock);
676   incrementProfileCounter(&S);
677   {
678     RunCleanupsScope ThenScope(*this);
679     EmitStmt(S.getThen());
680   }
681   EmitBranch(ContBlock);
682 
683   // Emit the 'else' code if present.
684   if (const Stmt *Else = S.getElse()) {
685     {
686       // There is no need to emit line number for an unconditional branch.
687       auto NL = ApplyDebugLocation::CreateEmpty(*this);
688       EmitBlock(ElseBlock);
689     }
690     {
691       RunCleanupsScope ElseScope(*this);
692       EmitStmt(Else);
693     }
694     {
695       // There is no need to emit line number for an unconditional branch.
696       auto NL = ApplyDebugLocation::CreateEmpty(*this);
697       EmitBranch(ContBlock);
698     }
699   }
700 
701   // Emit the continuation block for code after the if.
702   EmitBlock(ContBlock, true);
703 }
704 
705 void CodeGenFunction::EmitWhileStmt(const WhileStmt &S,
706                                     ArrayRef<const Attr *> WhileAttrs) {
707   // Emit the header for the loop, which will also become
708   // the continue target.
709   JumpDest LoopHeader = getJumpDestInCurrentScope("while.cond");
710   EmitBlock(LoopHeader.getBlock());
711 
712   const SourceRange &R = S.getSourceRange();
713   LoopStack.push(LoopHeader.getBlock(), CGM.getContext(), WhileAttrs,
714                  SourceLocToDebugLoc(R.getBegin()),
715                  SourceLocToDebugLoc(R.getEnd()));
716 
717   // Create an exit block for when the condition fails, which will
718   // also become the break target.
719   JumpDest LoopExit = getJumpDestInCurrentScope("while.end");
720 
721   // Store the blocks to use for break and continue.
722   BreakContinueStack.push_back(BreakContinue(LoopExit, LoopHeader));
723 
724   // C++ [stmt.while]p2:
725   //   When the condition of a while statement is a declaration, the
726   //   scope of the variable that is declared extends from its point
727   //   of declaration (3.3.2) to the end of the while statement.
728   //   [...]
729   //   The object created in a condition is destroyed and created
730   //   with each iteration of the loop.
731   RunCleanupsScope ConditionScope(*this);
732 
733   if (S.getConditionVariable())
734     EmitDecl(*S.getConditionVariable());
735 
736   // Evaluate the conditional in the while header.  C99 6.8.5.1: The
737   // evaluation of the controlling expression takes place before each
738   // execution of the loop body.
739   llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
740 
741   // while(1) is common, avoid extra exit blocks.  Be sure
742   // to correctly handle break/continue though.
743   bool EmitBoolCondBranch = true;
744   if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal))
745     if (C->isOne())
746       EmitBoolCondBranch = false;
747 
748   // As long as the condition is true, go to the loop body.
749   llvm::BasicBlock *LoopBody = createBasicBlock("while.body");
750   if (EmitBoolCondBranch) {
751     llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
752     if (ConditionScope.requiresCleanups())
753       ExitBlock = createBasicBlock("while.exit");
754     Builder.CreateCondBr(
755         BoolCondVal, LoopBody, ExitBlock,
756         createProfileWeightsForLoop(S.getCond(), getProfileCount(S.getBody())));
757 
758     if (ExitBlock != LoopExit.getBlock()) {
759       EmitBlock(ExitBlock);
760       EmitBranchThroughCleanup(LoopExit);
761     }
762   }
763 
764   // Emit the loop body.  We have to emit this in a cleanup scope
765   // because it might be a singleton DeclStmt.
766   {
767     RunCleanupsScope BodyScope(*this);
768     EmitBlock(LoopBody);
769     incrementProfileCounter(&S);
770     EmitStmt(S.getBody());
771   }
772 
773   BreakContinueStack.pop_back();
774 
775   // Immediately force cleanup.
776   ConditionScope.ForceCleanup();
777 
778   EmitStopPoint(&S);
779   // Branch to the loop header again.
780   EmitBranch(LoopHeader.getBlock());
781 
782   LoopStack.pop();
783 
784   // Emit the exit block.
785   EmitBlock(LoopExit.getBlock(), true);
786 
787   // The LoopHeader typically is just a branch if we skipped emitting
788   // a branch, try to erase it.
789   if (!EmitBoolCondBranch)
790     SimplifyForwardingBlocks(LoopHeader.getBlock());
791 }
792 
793 void CodeGenFunction::EmitDoStmt(const DoStmt &S,
794                                  ArrayRef<const Attr *> DoAttrs) {
795   JumpDest LoopExit = getJumpDestInCurrentScope("do.end");
796   JumpDest LoopCond = getJumpDestInCurrentScope("do.cond");
797 
798   uint64_t ParentCount = getCurrentProfileCount();
799 
800   // Store the blocks to use for break and continue.
801   BreakContinueStack.push_back(BreakContinue(LoopExit, LoopCond));
802 
803   // Emit the body of the loop.
804   llvm::BasicBlock *LoopBody = createBasicBlock("do.body");
805 
806   EmitBlockWithFallThrough(LoopBody, &S);
807   {
808     RunCleanupsScope BodyScope(*this);
809     EmitStmt(S.getBody());
810   }
811 
812   EmitBlock(LoopCond.getBlock());
813 
814   const SourceRange &R = S.getSourceRange();
815   LoopStack.push(LoopBody, CGM.getContext(), DoAttrs,
816                  SourceLocToDebugLoc(R.getBegin()),
817                  SourceLocToDebugLoc(R.getEnd()));
818 
819   // C99 6.8.5.2: "The evaluation of the controlling expression takes place
820   // after each execution of the loop body."
821 
822   // Evaluate the conditional in the while header.
823   // C99 6.8.5p2/p4: The first substatement is executed if the expression
824   // compares unequal to 0.  The condition must be a scalar type.
825   llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
826 
827   BreakContinueStack.pop_back();
828 
829   // "do {} while (0)" is common in macros, avoid extra blocks.  Be sure
830   // to correctly handle break/continue though.
831   bool EmitBoolCondBranch = true;
832   if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal))
833     if (C->isZero())
834       EmitBoolCondBranch = false;
835 
836   // As long as the condition is true, iterate the loop.
837   if (EmitBoolCondBranch) {
838     uint64_t BackedgeCount = getProfileCount(S.getBody()) - ParentCount;
839     Builder.CreateCondBr(
840         BoolCondVal, LoopBody, LoopExit.getBlock(),
841         createProfileWeightsForLoop(S.getCond(), BackedgeCount));
842   }
843 
844   LoopStack.pop();
845 
846   // Emit the exit block.
847   EmitBlock(LoopExit.getBlock());
848 
849   // The DoCond block typically is just a branch if we skipped
850   // emitting a branch, try to erase it.
851   if (!EmitBoolCondBranch)
852     SimplifyForwardingBlocks(LoopCond.getBlock());
853 }
854 
855 void CodeGenFunction::EmitForStmt(const ForStmt &S,
856                                   ArrayRef<const Attr *> ForAttrs) {
857   JumpDest LoopExit = getJumpDestInCurrentScope("for.end");
858 
859   LexicalScope ForScope(*this, S.getSourceRange());
860 
861   // Evaluate the first part before the loop.
862   if (S.getInit())
863     EmitStmt(S.getInit());
864 
865   // Start the loop with a block that tests the condition.
866   // If there's an increment, the continue scope will be overwritten
867   // later.
868   JumpDest Continue = getJumpDestInCurrentScope("for.cond");
869   llvm::BasicBlock *CondBlock = Continue.getBlock();
870   EmitBlock(CondBlock);
871 
872   const SourceRange &R = S.getSourceRange();
873   LoopStack.push(CondBlock, CGM.getContext(), ForAttrs,
874                  SourceLocToDebugLoc(R.getBegin()),
875                  SourceLocToDebugLoc(R.getEnd()));
876 
877   // If the for loop doesn't have an increment we can just use the
878   // condition as the continue block.  Otherwise we'll need to create
879   // a block for it (in the current scope, i.e. in the scope of the
880   // condition), and that we will become our continue block.
881   if (S.getInc())
882     Continue = getJumpDestInCurrentScope("for.inc");
883 
884   // Store the blocks to use for break and continue.
885   BreakContinueStack.push_back(BreakContinue(LoopExit, Continue));
886 
887   // Create a cleanup scope for the condition variable cleanups.
888   LexicalScope ConditionScope(*this, S.getSourceRange());
889 
890   if (S.getCond()) {
891     // If the for statement has a condition scope, emit the local variable
892     // declaration.
893     if (S.getConditionVariable()) {
894       EmitDecl(*S.getConditionVariable());
895     }
896 
897     llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
898     // If there are any cleanups between here and the loop-exit scope,
899     // create a block to stage a loop exit along.
900     if (ForScope.requiresCleanups())
901       ExitBlock = createBasicBlock("for.cond.cleanup");
902 
903     // As long as the condition is true, iterate the loop.
904     llvm::BasicBlock *ForBody = createBasicBlock("for.body");
905 
906     // C99 6.8.5p2/p4: The first substatement is executed if the expression
907     // compares unequal to 0.  The condition must be a scalar type.
908     llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
909     Builder.CreateCondBr(
910         BoolCondVal, ForBody, ExitBlock,
911         createProfileWeightsForLoop(S.getCond(), getProfileCount(S.getBody())));
912 
913     if (ExitBlock != LoopExit.getBlock()) {
914       EmitBlock(ExitBlock);
915       EmitBranchThroughCleanup(LoopExit);
916     }
917 
918     EmitBlock(ForBody);
919   } else {
920     // Treat it as a non-zero constant.  Don't even create a new block for the
921     // body, just fall into it.
922   }
923   incrementProfileCounter(&S);
924 
925   {
926     // Create a separate cleanup scope for the body, in case it is not
927     // a compound statement.
928     RunCleanupsScope BodyScope(*this);
929     EmitStmt(S.getBody());
930   }
931 
932   // If there is an increment, emit it next.
933   if (S.getInc()) {
934     EmitBlock(Continue.getBlock());
935     EmitStmt(S.getInc());
936   }
937 
938   BreakContinueStack.pop_back();
939 
940   ConditionScope.ForceCleanup();
941 
942   EmitStopPoint(&S);
943   EmitBranch(CondBlock);
944 
945   ForScope.ForceCleanup();
946 
947   LoopStack.pop();
948 
949   // Emit the fall-through block.
950   EmitBlock(LoopExit.getBlock(), true);
951 }
952 
953 void
954 CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S,
955                                      ArrayRef<const Attr *> ForAttrs) {
956   JumpDest LoopExit = getJumpDestInCurrentScope("for.end");
957 
958   LexicalScope ForScope(*this, S.getSourceRange());
959 
960   // Evaluate the first pieces before the loop.
961   if (S.getInit())
962     EmitStmt(S.getInit());
963   EmitStmt(S.getRangeStmt());
964   EmitStmt(S.getBeginStmt());
965   EmitStmt(S.getEndStmt());
966 
967   // Start the loop with a block that tests the condition.
968   // If there's an increment, the continue scope will be overwritten
969   // later.
970   llvm::BasicBlock *CondBlock = createBasicBlock("for.cond");
971   EmitBlock(CondBlock);
972 
973   const SourceRange &R = S.getSourceRange();
974   LoopStack.push(CondBlock, CGM.getContext(), ForAttrs,
975                  SourceLocToDebugLoc(R.getBegin()),
976                  SourceLocToDebugLoc(R.getEnd()));
977 
978   // If there are any cleanups between here and the loop-exit scope,
979   // create a block to stage a loop exit along.
980   llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
981   if (ForScope.requiresCleanups())
982     ExitBlock = createBasicBlock("for.cond.cleanup");
983 
984   // The loop body, consisting of the specified body and the loop variable.
985   llvm::BasicBlock *ForBody = createBasicBlock("for.body");
986 
987   // The body is executed if the expression, contextually converted
988   // to bool, is true.
989   llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
990   Builder.CreateCondBr(
991       BoolCondVal, ForBody, ExitBlock,
992       createProfileWeightsForLoop(S.getCond(), getProfileCount(S.getBody())));
993 
994   if (ExitBlock != LoopExit.getBlock()) {
995     EmitBlock(ExitBlock);
996     EmitBranchThroughCleanup(LoopExit);
997   }
998 
999   EmitBlock(ForBody);
1000   incrementProfileCounter(&S);
1001 
1002   // Create a block for the increment. In case of a 'continue', we jump there.
1003   JumpDest Continue = getJumpDestInCurrentScope("for.inc");
1004 
1005   // Store the blocks to use for break and continue.
1006   BreakContinueStack.push_back(BreakContinue(LoopExit, Continue));
1007 
1008   {
1009     // Create a separate cleanup scope for the loop variable and body.
1010     LexicalScope BodyScope(*this, S.getSourceRange());
1011     EmitStmt(S.getLoopVarStmt());
1012     EmitStmt(S.getBody());
1013   }
1014 
1015   EmitStopPoint(&S);
1016   // If there is an increment, emit it next.
1017   EmitBlock(Continue.getBlock());
1018   EmitStmt(S.getInc());
1019 
1020   BreakContinueStack.pop_back();
1021 
1022   EmitBranch(CondBlock);
1023 
1024   ForScope.ForceCleanup();
1025 
1026   LoopStack.pop();
1027 
1028   // Emit the fall-through block.
1029   EmitBlock(LoopExit.getBlock(), true);
1030 }
1031 
1032 void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) {
1033   if (RV.isScalar()) {
1034     Builder.CreateStore(RV.getScalarVal(), ReturnValue);
1035   } else if (RV.isAggregate()) {
1036     LValue Dest = MakeAddrLValue(ReturnValue, Ty);
1037     LValue Src = MakeAddrLValue(RV.getAggregateAddress(), Ty);
1038     EmitAggregateCopy(Dest, Src, Ty, getOverlapForReturnValue());
1039   } else {
1040     EmitStoreOfComplex(RV.getComplexVal(), MakeAddrLValue(ReturnValue, Ty),
1041                        /*init*/ true);
1042   }
1043   EmitBranchThroughCleanup(ReturnBlock);
1044 }
1045 
1046 /// EmitReturnStmt - Note that due to GCC extensions, this can have an operand
1047 /// if the function returns void, or may be missing one if the function returns
1048 /// non-void.  Fun stuff :).
1049 void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) {
1050   if (requiresReturnValueCheck()) {
1051     llvm::Constant *SLoc = EmitCheckSourceLocation(S.getBeginLoc());
1052     auto *SLocPtr =
1053         new llvm::GlobalVariable(CGM.getModule(), SLoc->getType(), false,
1054                                  llvm::GlobalVariable::PrivateLinkage, SLoc);
1055     SLocPtr->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1056     CGM.getSanitizerMetadata()->disableSanitizerForGlobal(SLocPtr);
1057     assert(ReturnLocation.isValid() && "No valid return location");
1058     Builder.CreateStore(Builder.CreateBitCast(SLocPtr, Int8PtrTy),
1059                         ReturnLocation);
1060   }
1061 
1062   // Returning from an outlined SEH helper is UB, and we already warn on it.
1063   if (IsOutlinedSEHHelper) {
1064     Builder.CreateUnreachable();
1065     Builder.ClearInsertionPoint();
1066   }
1067 
1068   // Emit the result value, even if unused, to evaluate the side effects.
1069   const Expr *RV = S.getRetValue();
1070 
1071   // Treat block literals in a return expression as if they appeared
1072   // in their own scope.  This permits a small, easily-implemented
1073   // exception to our over-conservative rules about not jumping to
1074   // statements following block literals with non-trivial cleanups.
1075   RunCleanupsScope cleanupScope(*this);
1076   if (const FullExpr *fe = dyn_cast_or_null<FullExpr>(RV)) {
1077     enterFullExpression(fe);
1078     RV = fe->getSubExpr();
1079   }
1080 
1081   // FIXME: Clean this up by using an LValue for ReturnTemp,
1082   // EmitStoreThroughLValue, and EmitAnyExpr.
1083   if (getLangOpts().ElideConstructors &&
1084       S.getNRVOCandidate() && S.getNRVOCandidate()->isNRVOVariable()) {
1085     // Apply the named return value optimization for this return statement,
1086     // which means doing nothing: the appropriate result has already been
1087     // constructed into the NRVO variable.
1088 
1089     // If there is an NRVO flag for this variable, set it to 1 into indicate
1090     // that the cleanup code should not destroy the variable.
1091     if (llvm::Value *NRVOFlag = NRVOFlags[S.getNRVOCandidate()])
1092       Builder.CreateFlagStore(Builder.getTrue(), NRVOFlag);
1093   } else if (!ReturnValue.isValid() || (RV && RV->getType()->isVoidType())) {
1094     // Make sure not to return anything, but evaluate the expression
1095     // for side effects.
1096     if (RV)
1097       EmitAnyExpr(RV);
1098   } else if (!RV) {
1099     // Do nothing (return value is left uninitialized)
1100   } else if (FnRetTy->isReferenceType()) {
1101     // If this function returns a reference, take the address of the expression
1102     // rather than the value.
1103     RValue Result = EmitReferenceBindingToExpr(RV);
1104     Builder.CreateStore(Result.getScalarVal(), ReturnValue);
1105   } else {
1106     switch (getEvaluationKind(RV->getType())) {
1107     case TEK_Scalar:
1108       Builder.CreateStore(EmitScalarExpr(RV), ReturnValue);
1109       break;
1110     case TEK_Complex:
1111       EmitComplexExprIntoLValue(RV, MakeAddrLValue(ReturnValue, RV->getType()),
1112                                 /*isInit*/ true);
1113       break;
1114     case TEK_Aggregate:
1115       EmitAggExpr(RV, AggValueSlot::forAddr(
1116                           ReturnValue, Qualifiers(),
1117                           AggValueSlot::IsDestructed,
1118                           AggValueSlot::DoesNotNeedGCBarriers,
1119                           AggValueSlot::IsNotAliased,
1120                           getOverlapForReturnValue()));
1121       break;
1122     }
1123   }
1124 
1125   ++NumReturnExprs;
1126   if (!RV || RV->isEvaluatable(getContext()))
1127     ++NumSimpleReturnExprs;
1128 
1129   cleanupScope.ForceCleanup();
1130   EmitBranchThroughCleanup(ReturnBlock);
1131 }
1132 
1133 void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) {
1134   // As long as debug info is modeled with instructions, we have to ensure we
1135   // have a place to insert here and write the stop point here.
1136   if (HaveInsertPoint())
1137     EmitStopPoint(&S);
1138 
1139   for (const auto *I : S.decls())
1140     EmitDecl(*I);
1141 }
1142 
1143 void CodeGenFunction::EmitBreakStmt(const BreakStmt &S) {
1144   assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!");
1145 
1146   // If this code is reachable then emit a stop point (if generating
1147   // debug info). We have to do this ourselves because we are on the
1148   // "simple" statement path.
1149   if (HaveInsertPoint())
1150     EmitStopPoint(&S);
1151 
1152   EmitBranchThroughCleanup(BreakContinueStack.back().BreakBlock);
1153 }
1154 
1155 void CodeGenFunction::EmitContinueStmt(const ContinueStmt &S) {
1156   assert(!BreakContinueStack.empty() && "continue stmt not in a loop!");
1157 
1158   // If this code is reachable then emit a stop point (if generating
1159   // debug info). We have to do this ourselves because we are on the
1160   // "simple" statement path.
1161   if (HaveInsertPoint())
1162     EmitStopPoint(&S);
1163 
1164   EmitBranchThroughCleanup(BreakContinueStack.back().ContinueBlock);
1165 }
1166 
1167 /// EmitCaseStmtRange - If case statement range is not too big then
1168 /// add multiple cases to switch instruction, one for each value within
1169 /// the range. If range is too big then emit "if" condition check.
1170 void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S) {
1171   assert(S.getRHS() && "Expected RHS value in CaseStmt");
1172 
1173   llvm::APSInt LHS = S.getLHS()->EvaluateKnownConstInt(getContext());
1174   llvm::APSInt RHS = S.getRHS()->EvaluateKnownConstInt(getContext());
1175 
1176   // Emit the code for this case. We do this first to make sure it is
1177   // properly chained from our predecessor before generating the
1178   // switch machinery to enter this block.
1179   llvm::BasicBlock *CaseDest = createBasicBlock("sw.bb");
1180   EmitBlockWithFallThrough(CaseDest, &S);
1181   EmitStmt(S.getSubStmt());
1182 
1183   // If range is empty, do nothing.
1184   if (LHS.isSigned() ? RHS.slt(LHS) : RHS.ult(LHS))
1185     return;
1186 
1187   llvm::APInt Range = RHS - LHS;
1188   // FIXME: parameters such as this should not be hardcoded.
1189   if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) {
1190     // Range is small enough to add multiple switch instruction cases.
1191     uint64_t Total = getProfileCount(&S);
1192     unsigned NCases = Range.getZExtValue() + 1;
1193     // We only have one region counter for the entire set of cases here, so we
1194     // need to divide the weights evenly between the generated cases, ensuring
1195     // that the total weight is preserved. E.g., a weight of 5 over three cases
1196     // will be distributed as weights of 2, 2, and 1.
1197     uint64_t Weight = Total / NCases, Rem = Total % NCases;
1198     for (unsigned I = 0; I != NCases; ++I) {
1199       if (SwitchWeights)
1200         SwitchWeights->push_back(Weight + (Rem ? 1 : 0));
1201       if (Rem)
1202         Rem--;
1203       SwitchInsn->addCase(Builder.getInt(LHS), CaseDest);
1204       ++LHS;
1205     }
1206     return;
1207   }
1208 
1209   // The range is too big. Emit "if" condition into a new block,
1210   // making sure to save and restore the current insertion point.
1211   llvm::BasicBlock *RestoreBB = Builder.GetInsertBlock();
1212 
1213   // Push this test onto the chain of range checks (which terminates
1214   // in the default basic block). The switch's default will be changed
1215   // to the top of this chain after switch emission is complete.
1216   llvm::BasicBlock *FalseDest = CaseRangeBlock;
1217   CaseRangeBlock = createBasicBlock("sw.caserange");
1218 
1219   CurFn->getBasicBlockList().push_back(CaseRangeBlock);
1220   Builder.SetInsertPoint(CaseRangeBlock);
1221 
1222   // Emit range check.
1223   llvm::Value *Diff =
1224     Builder.CreateSub(SwitchInsn->getCondition(), Builder.getInt(LHS));
1225   llvm::Value *Cond =
1226     Builder.CreateICmpULE(Diff, Builder.getInt(Range), "inbounds");
1227 
1228   llvm::MDNode *Weights = nullptr;
1229   if (SwitchWeights) {
1230     uint64_t ThisCount = getProfileCount(&S);
1231     uint64_t DefaultCount = (*SwitchWeights)[0];
1232     Weights = createProfileWeights(ThisCount, DefaultCount);
1233 
1234     // Since we're chaining the switch default through each large case range, we
1235     // need to update the weight for the default, ie, the first case, to include
1236     // this case.
1237     (*SwitchWeights)[0] += ThisCount;
1238   }
1239   Builder.CreateCondBr(Cond, CaseDest, FalseDest, Weights);
1240 
1241   // Restore the appropriate insertion point.
1242   if (RestoreBB)
1243     Builder.SetInsertPoint(RestoreBB);
1244   else
1245     Builder.ClearInsertionPoint();
1246 }
1247 
1248 void CodeGenFunction::EmitCaseStmt(const CaseStmt &S) {
1249   // If there is no enclosing switch instance that we're aware of, then this
1250   // case statement and its block can be elided.  This situation only happens
1251   // when we've constant-folded the switch, are emitting the constant case,
1252   // and part of the constant case includes another case statement.  For
1253   // instance: switch (4) { case 4: do { case 5: } while (1); }
1254   if (!SwitchInsn) {
1255     EmitStmt(S.getSubStmt());
1256     return;
1257   }
1258 
1259   // Handle case ranges.
1260   if (S.getRHS()) {
1261     EmitCaseStmtRange(S);
1262     return;
1263   }
1264 
1265   llvm::ConstantInt *CaseVal =
1266     Builder.getInt(S.getLHS()->EvaluateKnownConstInt(getContext()));
1267 
1268   // If the body of the case is just a 'break', try to not emit an empty block.
1269   // If we're profiling or we're not optimizing, leave the block in for better
1270   // debug and coverage analysis.
1271   if (!CGM.getCodeGenOpts().hasProfileClangInstr() &&
1272       CGM.getCodeGenOpts().OptimizationLevel > 0 &&
1273       isa<BreakStmt>(S.getSubStmt())) {
1274     JumpDest Block = BreakContinueStack.back().BreakBlock;
1275 
1276     // Only do this optimization if there are no cleanups that need emitting.
1277     if (isObviouslyBranchWithoutCleanups(Block)) {
1278       if (SwitchWeights)
1279         SwitchWeights->push_back(getProfileCount(&S));
1280       SwitchInsn->addCase(CaseVal, Block.getBlock());
1281 
1282       // If there was a fallthrough into this case, make sure to redirect it to
1283       // the end of the switch as well.
1284       if (Builder.GetInsertBlock()) {
1285         Builder.CreateBr(Block.getBlock());
1286         Builder.ClearInsertionPoint();
1287       }
1288       return;
1289     }
1290   }
1291 
1292   llvm::BasicBlock *CaseDest = createBasicBlock("sw.bb");
1293   EmitBlockWithFallThrough(CaseDest, &S);
1294   if (SwitchWeights)
1295     SwitchWeights->push_back(getProfileCount(&S));
1296   SwitchInsn->addCase(CaseVal, CaseDest);
1297 
1298   // Recursively emitting the statement is acceptable, but is not wonderful for
1299   // code where we have many case statements nested together, i.e.:
1300   //  case 1:
1301   //    case 2:
1302   //      case 3: etc.
1303   // Handling this recursively will create a new block for each case statement
1304   // that falls through to the next case which is IR intensive.  It also causes
1305   // deep recursion which can run into stack depth limitations.  Handle
1306   // sequential non-range case statements specially.
1307   const CaseStmt *CurCase = &S;
1308   const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt());
1309 
1310   // Otherwise, iteratively add consecutive cases to this switch stmt.
1311   while (NextCase && NextCase->getRHS() == nullptr) {
1312     CurCase = NextCase;
1313     llvm::ConstantInt *CaseVal =
1314       Builder.getInt(CurCase->getLHS()->EvaluateKnownConstInt(getContext()));
1315 
1316     if (SwitchWeights)
1317       SwitchWeights->push_back(getProfileCount(NextCase));
1318     if (CGM.getCodeGenOpts().hasProfileClangInstr()) {
1319       CaseDest = createBasicBlock("sw.bb");
1320       EmitBlockWithFallThrough(CaseDest, &S);
1321     }
1322 
1323     SwitchInsn->addCase(CaseVal, CaseDest);
1324     NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt());
1325   }
1326 
1327   // Normal default recursion for non-cases.
1328   EmitStmt(CurCase->getSubStmt());
1329 }
1330 
1331 void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S) {
1332   // If there is no enclosing switch instance that we're aware of, then this
1333   // default statement can be elided. This situation only happens when we've
1334   // constant-folded the switch.
1335   if (!SwitchInsn) {
1336     EmitStmt(S.getSubStmt());
1337     return;
1338   }
1339 
1340   llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest();
1341   assert(DefaultBlock->empty() &&
1342          "EmitDefaultStmt: Default block already defined?");
1343 
1344   EmitBlockWithFallThrough(DefaultBlock, &S);
1345 
1346   EmitStmt(S.getSubStmt());
1347 }
1348 
1349 /// CollectStatementsForCase - Given the body of a 'switch' statement and a
1350 /// constant value that is being switched on, see if we can dead code eliminate
1351 /// the body of the switch to a simple series of statements to emit.  Basically,
1352 /// on a switch (5) we want to find these statements:
1353 ///    case 5:
1354 ///      printf(...);    <--
1355 ///      ++i;            <--
1356 ///      break;
1357 ///
1358 /// and add them to the ResultStmts vector.  If it is unsafe to do this
1359 /// transformation (for example, one of the elided statements contains a label
1360 /// that might be jumped to), return CSFC_Failure.  If we handled it and 'S'
1361 /// should include statements after it (e.g. the printf() line is a substmt of
1362 /// the case) then return CSFC_FallThrough.  If we handled it and found a break
1363 /// statement, then return CSFC_Success.
1364 ///
1365 /// If Case is non-null, then we are looking for the specified case, checking
1366 /// that nothing we jump over contains labels.  If Case is null, then we found
1367 /// the case and are looking for the break.
1368 ///
1369 /// If the recursive walk actually finds our Case, then we set FoundCase to
1370 /// true.
1371 ///
1372 enum CSFC_Result { CSFC_Failure, CSFC_FallThrough, CSFC_Success };
1373 static CSFC_Result CollectStatementsForCase(const Stmt *S,
1374                                             const SwitchCase *Case,
1375                                             bool &FoundCase,
1376                               SmallVectorImpl<const Stmt*> &ResultStmts) {
1377   // If this is a null statement, just succeed.
1378   if (!S)
1379     return Case ? CSFC_Success : CSFC_FallThrough;
1380 
1381   // If this is the switchcase (case 4: or default) that we're looking for, then
1382   // we're in business.  Just add the substatement.
1383   if (const SwitchCase *SC = dyn_cast<SwitchCase>(S)) {
1384     if (S == Case) {
1385       FoundCase = true;
1386       return CollectStatementsForCase(SC->getSubStmt(), nullptr, FoundCase,
1387                                       ResultStmts);
1388     }
1389 
1390     // Otherwise, this is some other case or default statement, just ignore it.
1391     return CollectStatementsForCase(SC->getSubStmt(), Case, FoundCase,
1392                                     ResultStmts);
1393   }
1394 
1395   // If we are in the live part of the code and we found our break statement,
1396   // return a success!
1397   if (!Case && isa<BreakStmt>(S))
1398     return CSFC_Success;
1399 
1400   // If this is a switch statement, then it might contain the SwitchCase, the
1401   // break, or neither.
1402   if (const CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) {
1403     // Handle this as two cases: we might be looking for the SwitchCase (if so
1404     // the skipped statements must be skippable) or we might already have it.
1405     CompoundStmt::const_body_iterator I = CS->body_begin(), E = CS->body_end();
1406     bool StartedInLiveCode = FoundCase;
1407     unsigned StartSize = ResultStmts.size();
1408 
1409     // If we've not found the case yet, scan through looking for it.
1410     if (Case) {
1411       // Keep track of whether we see a skipped declaration.  The code could be
1412       // using the declaration even if it is skipped, so we can't optimize out
1413       // the decl if the kept statements might refer to it.
1414       bool HadSkippedDecl = false;
1415 
1416       // If we're looking for the case, just see if we can skip each of the
1417       // substatements.
1418       for (; Case && I != E; ++I) {
1419         HadSkippedDecl |= CodeGenFunction::mightAddDeclToScope(*I);
1420 
1421         switch (CollectStatementsForCase(*I, Case, FoundCase, ResultStmts)) {
1422         case CSFC_Failure: return CSFC_Failure;
1423         case CSFC_Success:
1424           // A successful result means that either 1) that the statement doesn't
1425           // have the case and is skippable, or 2) does contain the case value
1426           // and also contains the break to exit the switch.  In the later case,
1427           // we just verify the rest of the statements are elidable.
1428           if (FoundCase) {
1429             // If we found the case and skipped declarations, we can't do the
1430             // optimization.
1431             if (HadSkippedDecl)
1432               return CSFC_Failure;
1433 
1434             for (++I; I != E; ++I)
1435               if (CodeGenFunction::ContainsLabel(*I, true))
1436                 return CSFC_Failure;
1437             return CSFC_Success;
1438           }
1439           break;
1440         case CSFC_FallThrough:
1441           // If we have a fallthrough condition, then we must have found the
1442           // case started to include statements.  Consider the rest of the
1443           // statements in the compound statement as candidates for inclusion.
1444           assert(FoundCase && "Didn't find case but returned fallthrough?");
1445           // We recursively found Case, so we're not looking for it anymore.
1446           Case = nullptr;
1447 
1448           // If we found the case and skipped declarations, we can't do the
1449           // optimization.
1450           if (HadSkippedDecl)
1451             return CSFC_Failure;
1452           break;
1453         }
1454       }
1455 
1456       if (!FoundCase)
1457         return CSFC_Success;
1458 
1459       assert(!HadSkippedDecl && "fallthrough after skipping decl");
1460     }
1461 
1462     // If we have statements in our range, then we know that the statements are
1463     // live and need to be added to the set of statements we're tracking.
1464     bool AnyDecls = false;
1465     for (; I != E; ++I) {
1466       AnyDecls |= CodeGenFunction::mightAddDeclToScope(*I);
1467 
1468       switch (CollectStatementsForCase(*I, nullptr, FoundCase, ResultStmts)) {
1469       case CSFC_Failure: return CSFC_Failure;
1470       case CSFC_FallThrough:
1471         // A fallthrough result means that the statement was simple and just
1472         // included in ResultStmt, keep adding them afterwards.
1473         break;
1474       case CSFC_Success:
1475         // A successful result means that we found the break statement and
1476         // stopped statement inclusion.  We just ensure that any leftover stmts
1477         // are skippable and return success ourselves.
1478         for (++I; I != E; ++I)
1479           if (CodeGenFunction::ContainsLabel(*I, true))
1480             return CSFC_Failure;
1481         return CSFC_Success;
1482       }
1483     }
1484 
1485     // If we're about to fall out of a scope without hitting a 'break;', we
1486     // can't perform the optimization if there were any decls in that scope
1487     // (we'd lose their end-of-lifetime).
1488     if (AnyDecls) {
1489       // If the entire compound statement was live, there's one more thing we
1490       // can try before giving up: emit the whole thing as a single statement.
1491       // We can do that unless the statement contains a 'break;'.
1492       // FIXME: Such a break must be at the end of a construct within this one.
1493       // We could emit this by just ignoring the BreakStmts entirely.
1494       if (StartedInLiveCode && !CodeGenFunction::containsBreak(S)) {
1495         ResultStmts.resize(StartSize);
1496         ResultStmts.push_back(S);
1497       } else {
1498         return CSFC_Failure;
1499       }
1500     }
1501 
1502     return CSFC_FallThrough;
1503   }
1504 
1505   // Okay, this is some other statement that we don't handle explicitly, like a
1506   // for statement or increment etc.  If we are skipping over this statement,
1507   // just verify it doesn't have labels, which would make it invalid to elide.
1508   if (Case) {
1509     if (CodeGenFunction::ContainsLabel(S, true))
1510       return CSFC_Failure;
1511     return CSFC_Success;
1512   }
1513 
1514   // Otherwise, we want to include this statement.  Everything is cool with that
1515   // so long as it doesn't contain a break out of the switch we're in.
1516   if (CodeGenFunction::containsBreak(S)) return CSFC_Failure;
1517 
1518   // Otherwise, everything is great.  Include the statement and tell the caller
1519   // that we fall through and include the next statement as well.
1520   ResultStmts.push_back(S);
1521   return CSFC_FallThrough;
1522 }
1523 
1524 /// FindCaseStatementsForValue - Find the case statement being jumped to and
1525 /// then invoke CollectStatementsForCase to find the list of statements to emit
1526 /// for a switch on constant.  See the comment above CollectStatementsForCase
1527 /// for more details.
1528 static bool FindCaseStatementsForValue(const SwitchStmt &S,
1529                                        const llvm::APSInt &ConstantCondValue,
1530                                 SmallVectorImpl<const Stmt*> &ResultStmts,
1531                                        ASTContext &C,
1532                                        const SwitchCase *&ResultCase) {
1533   // First step, find the switch case that is being branched to.  We can do this
1534   // efficiently by scanning the SwitchCase list.
1535   const SwitchCase *Case = S.getSwitchCaseList();
1536   const DefaultStmt *DefaultCase = nullptr;
1537 
1538   for (; Case; Case = Case->getNextSwitchCase()) {
1539     // It's either a default or case.  Just remember the default statement in
1540     // case we're not jumping to any numbered cases.
1541     if (const DefaultStmt *DS = dyn_cast<DefaultStmt>(Case)) {
1542       DefaultCase = DS;
1543       continue;
1544     }
1545 
1546     // Check to see if this case is the one we're looking for.
1547     const CaseStmt *CS = cast<CaseStmt>(Case);
1548     // Don't handle case ranges yet.
1549     if (CS->getRHS()) return false;
1550 
1551     // If we found our case, remember it as 'case'.
1552     if (CS->getLHS()->EvaluateKnownConstInt(C) == ConstantCondValue)
1553       break;
1554   }
1555 
1556   // If we didn't find a matching case, we use a default if it exists, or we
1557   // elide the whole switch body!
1558   if (!Case) {
1559     // It is safe to elide the body of the switch if it doesn't contain labels
1560     // etc.  If it is safe, return successfully with an empty ResultStmts list.
1561     if (!DefaultCase)
1562       return !CodeGenFunction::ContainsLabel(&S);
1563     Case = DefaultCase;
1564   }
1565 
1566   // Ok, we know which case is being jumped to, try to collect all the
1567   // statements that follow it.  This can fail for a variety of reasons.  Also,
1568   // check to see that the recursive walk actually found our case statement.
1569   // Insane cases like this can fail to find it in the recursive walk since we
1570   // don't handle every stmt kind:
1571   // switch (4) {
1572   //   while (1) {
1573   //     case 4: ...
1574   bool FoundCase = false;
1575   ResultCase = Case;
1576   return CollectStatementsForCase(S.getBody(), Case, FoundCase,
1577                                   ResultStmts) != CSFC_Failure &&
1578          FoundCase;
1579 }
1580 
1581 void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) {
1582   // Handle nested switch statements.
1583   llvm::SwitchInst *SavedSwitchInsn = SwitchInsn;
1584   SmallVector<uint64_t, 16> *SavedSwitchWeights = SwitchWeights;
1585   llvm::BasicBlock *SavedCRBlock = CaseRangeBlock;
1586 
1587   // See if we can constant fold the condition of the switch and therefore only
1588   // emit the live case statement (if any) of the switch.
1589   llvm::APSInt ConstantCondValue;
1590   if (ConstantFoldsToSimpleInteger(S.getCond(), ConstantCondValue)) {
1591     SmallVector<const Stmt*, 4> CaseStmts;
1592     const SwitchCase *Case = nullptr;
1593     if (FindCaseStatementsForValue(S, ConstantCondValue, CaseStmts,
1594                                    getContext(), Case)) {
1595       if (Case)
1596         incrementProfileCounter(Case);
1597       RunCleanupsScope ExecutedScope(*this);
1598 
1599       if (S.getInit())
1600         EmitStmt(S.getInit());
1601 
1602       // Emit the condition variable if needed inside the entire cleanup scope
1603       // used by this special case for constant folded switches.
1604       if (S.getConditionVariable())
1605         EmitDecl(*S.getConditionVariable());
1606 
1607       // At this point, we are no longer "within" a switch instance, so
1608       // we can temporarily enforce this to ensure that any embedded case
1609       // statements are not emitted.
1610       SwitchInsn = nullptr;
1611 
1612       // Okay, we can dead code eliminate everything except this case.  Emit the
1613       // specified series of statements and we're good.
1614       for (unsigned i = 0, e = CaseStmts.size(); i != e; ++i)
1615         EmitStmt(CaseStmts[i]);
1616       incrementProfileCounter(&S);
1617 
1618       // Now we want to restore the saved switch instance so that nested
1619       // switches continue to function properly
1620       SwitchInsn = SavedSwitchInsn;
1621 
1622       return;
1623     }
1624   }
1625 
1626   JumpDest SwitchExit = getJumpDestInCurrentScope("sw.epilog");
1627 
1628   RunCleanupsScope ConditionScope(*this);
1629 
1630   if (S.getInit())
1631     EmitStmt(S.getInit());
1632 
1633   if (S.getConditionVariable())
1634     EmitDecl(*S.getConditionVariable());
1635   llvm::Value *CondV = EmitScalarExpr(S.getCond());
1636 
1637   // Create basic block to hold stuff that comes after switch
1638   // statement. We also need to create a default block now so that
1639   // explicit case ranges tests can have a place to jump to on
1640   // failure.
1641   llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default");
1642   SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock);
1643   if (PGO.haveRegionCounts()) {
1644     // Walk the SwitchCase list to find how many there are.
1645     uint64_t DefaultCount = 0;
1646     unsigned NumCases = 0;
1647     for (const SwitchCase *Case = S.getSwitchCaseList();
1648          Case;
1649          Case = Case->getNextSwitchCase()) {
1650       if (isa<DefaultStmt>(Case))
1651         DefaultCount = getProfileCount(Case);
1652       NumCases += 1;
1653     }
1654     SwitchWeights = new SmallVector<uint64_t, 16>();
1655     SwitchWeights->reserve(NumCases);
1656     // The default needs to be first. We store the edge count, so we already
1657     // know the right weight.
1658     SwitchWeights->push_back(DefaultCount);
1659   }
1660   CaseRangeBlock = DefaultBlock;
1661 
1662   // Clear the insertion point to indicate we are in unreachable code.
1663   Builder.ClearInsertionPoint();
1664 
1665   // All break statements jump to NextBlock. If BreakContinueStack is non-empty
1666   // then reuse last ContinueBlock.
1667   JumpDest OuterContinue;
1668   if (!BreakContinueStack.empty())
1669     OuterContinue = BreakContinueStack.back().ContinueBlock;
1670 
1671   BreakContinueStack.push_back(BreakContinue(SwitchExit, OuterContinue));
1672 
1673   // Emit switch body.
1674   EmitStmt(S.getBody());
1675 
1676   BreakContinueStack.pop_back();
1677 
1678   // Update the default block in case explicit case range tests have
1679   // been chained on top.
1680   SwitchInsn->setDefaultDest(CaseRangeBlock);
1681 
1682   // If a default was never emitted:
1683   if (!DefaultBlock->getParent()) {
1684     // If we have cleanups, emit the default block so that there's a
1685     // place to jump through the cleanups from.
1686     if (ConditionScope.requiresCleanups()) {
1687       EmitBlock(DefaultBlock);
1688 
1689     // Otherwise, just forward the default block to the switch end.
1690     } else {
1691       DefaultBlock->replaceAllUsesWith(SwitchExit.getBlock());
1692       delete DefaultBlock;
1693     }
1694   }
1695 
1696   ConditionScope.ForceCleanup();
1697 
1698   // Emit continuation.
1699   EmitBlock(SwitchExit.getBlock(), true);
1700   incrementProfileCounter(&S);
1701 
1702   // If the switch has a condition wrapped by __builtin_unpredictable,
1703   // create metadata that specifies that the switch is unpredictable.
1704   // Don't bother if not optimizing because that metadata would not be used.
1705   auto *Call = dyn_cast<CallExpr>(S.getCond());
1706   if (Call && CGM.getCodeGenOpts().OptimizationLevel != 0) {
1707     auto *FD = dyn_cast_or_null<FunctionDecl>(Call->getCalleeDecl());
1708     if (FD && FD->getBuiltinID() == Builtin::BI__builtin_unpredictable) {
1709       llvm::MDBuilder MDHelper(getLLVMContext());
1710       SwitchInsn->setMetadata(llvm::LLVMContext::MD_unpredictable,
1711                               MDHelper.createUnpredictable());
1712     }
1713   }
1714 
1715   if (SwitchWeights) {
1716     assert(SwitchWeights->size() == 1 + SwitchInsn->getNumCases() &&
1717            "switch weights do not match switch cases");
1718     // If there's only one jump destination there's no sense weighting it.
1719     if (SwitchWeights->size() > 1)
1720       SwitchInsn->setMetadata(llvm::LLVMContext::MD_prof,
1721                               createProfileWeights(*SwitchWeights));
1722     delete SwitchWeights;
1723   }
1724   SwitchInsn = SavedSwitchInsn;
1725   SwitchWeights = SavedSwitchWeights;
1726   CaseRangeBlock = SavedCRBlock;
1727 }
1728 
1729 static std::string
1730 SimplifyConstraint(const char *Constraint, const TargetInfo &Target,
1731                  SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=nullptr) {
1732   std::string Result;
1733 
1734   while (*Constraint) {
1735     switch (*Constraint) {
1736     default:
1737       Result += Target.convertConstraint(Constraint);
1738       break;
1739     // Ignore these
1740     case '*':
1741     case '?':
1742     case '!':
1743     case '=': // Will see this and the following in mult-alt constraints.
1744     case '+':
1745       break;
1746     case '#': // Ignore the rest of the constraint alternative.
1747       while (Constraint[1] && Constraint[1] != ',')
1748         Constraint++;
1749       break;
1750     case '&':
1751     case '%':
1752       Result += *Constraint;
1753       while (Constraint[1] && Constraint[1] == *Constraint)
1754         Constraint++;
1755       break;
1756     case ',':
1757       Result += "|";
1758       break;
1759     case 'g':
1760       Result += "imr";
1761       break;
1762     case '[': {
1763       assert(OutCons &&
1764              "Must pass output names to constraints with a symbolic name");
1765       unsigned Index;
1766       bool result = Target.resolveSymbolicName(Constraint, *OutCons, Index);
1767       assert(result && "Could not resolve symbolic name"); (void)result;
1768       Result += llvm::utostr(Index);
1769       break;
1770     }
1771     }
1772 
1773     Constraint++;
1774   }
1775 
1776   return Result;
1777 }
1778 
1779 /// AddVariableConstraints - Look at AsmExpr and if it is a variable declared
1780 /// as using a particular register add that as a constraint that will be used
1781 /// in this asm stmt.
1782 static std::string
1783 AddVariableConstraints(const std::string &Constraint, const Expr &AsmExpr,
1784                        const TargetInfo &Target, CodeGenModule &CGM,
1785                        const AsmStmt &Stmt, const bool EarlyClobber) {
1786   const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(&AsmExpr);
1787   if (!AsmDeclRef)
1788     return Constraint;
1789   const ValueDecl &Value = *AsmDeclRef->getDecl();
1790   const VarDecl *Variable = dyn_cast<VarDecl>(&Value);
1791   if (!Variable)
1792     return Constraint;
1793   if (Variable->getStorageClass() != SC_Register)
1794     return Constraint;
1795   AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>();
1796   if (!Attr)
1797     return Constraint;
1798   StringRef Register = Attr->getLabel();
1799   assert(Target.isValidGCCRegisterName(Register));
1800   // We're using validateOutputConstraint here because we only care if
1801   // this is a register constraint.
1802   TargetInfo::ConstraintInfo Info(Constraint, "");
1803   if (Target.validateOutputConstraint(Info) &&
1804       !Info.allowsRegister()) {
1805     CGM.ErrorUnsupported(&Stmt, "__asm__");
1806     return Constraint;
1807   }
1808   // Canonicalize the register here before returning it.
1809   Register = Target.getNormalizedGCCRegisterName(Register);
1810   return (EarlyClobber ? "&{" : "{") + Register.str() + "}";
1811 }
1812 
1813 llvm::Value*
1814 CodeGenFunction::EmitAsmInputLValue(const TargetInfo::ConstraintInfo &Info,
1815                                     LValue InputValue, QualType InputType,
1816                                     std::string &ConstraintStr,
1817                                     SourceLocation Loc) {
1818   llvm::Value *Arg;
1819   if (Info.allowsRegister() || !Info.allowsMemory()) {
1820     if (CodeGenFunction::hasScalarEvaluationKind(InputType)) {
1821       Arg = EmitLoadOfLValue(InputValue, Loc).getScalarVal();
1822     } else {
1823       llvm::Type *Ty = ConvertType(InputType);
1824       uint64_t Size = CGM.getDataLayout().getTypeSizeInBits(Ty);
1825       if (Size <= 64 && llvm::isPowerOf2_64(Size)) {
1826         Ty = llvm::IntegerType::get(getLLVMContext(), Size);
1827         Ty = llvm::PointerType::getUnqual(Ty);
1828 
1829         Arg = Builder.CreateLoad(Builder.CreateBitCast(InputValue.getAddress(),
1830                                                        Ty));
1831       } else {
1832         Arg = InputValue.getPointer();
1833         ConstraintStr += '*';
1834       }
1835     }
1836   } else {
1837     Arg = InputValue.getPointer();
1838     ConstraintStr += '*';
1839   }
1840 
1841   return Arg;
1842 }
1843 
1844 llvm::Value* CodeGenFunction::EmitAsmInput(
1845                                          const TargetInfo::ConstraintInfo &Info,
1846                                            const Expr *InputExpr,
1847                                            std::string &ConstraintStr) {
1848   // If this can't be a register or memory, i.e., has to be a constant
1849   // (immediate or symbolic), try to emit it as such.
1850   if (!Info.allowsRegister() && !Info.allowsMemory()) {
1851     if (Info.requiresImmediateConstant()) {
1852       Expr::EvalResult EVResult;
1853       InputExpr->EvaluateAsRValue(EVResult, getContext(), true);
1854 
1855       llvm::APSInt IntResult;
1856       if (EVResult.Val.toIntegralConstant(IntResult, InputExpr->getType(),
1857                                           getContext()))
1858         return llvm::ConstantInt::get(getLLVMContext(), IntResult);
1859     }
1860 
1861     Expr::EvalResult Result;
1862     if (InputExpr->EvaluateAsInt(Result, getContext()))
1863       return llvm::ConstantInt::get(getLLVMContext(), Result.Val.getInt());
1864   }
1865 
1866   if (Info.allowsRegister() || !Info.allowsMemory())
1867     if (CodeGenFunction::hasScalarEvaluationKind(InputExpr->getType()))
1868       return EmitScalarExpr(InputExpr);
1869   if (InputExpr->getStmtClass() == Expr::CXXThisExprClass)
1870     return EmitScalarExpr(InputExpr);
1871   InputExpr = InputExpr->IgnoreParenNoopCasts(getContext());
1872   LValue Dest = EmitLValue(InputExpr);
1873   return EmitAsmInputLValue(Info, Dest, InputExpr->getType(), ConstraintStr,
1874                             InputExpr->getExprLoc());
1875 }
1876 
1877 /// getAsmSrcLocInfo - Return the !srcloc metadata node to attach to an inline
1878 /// asm call instruction.  The !srcloc MDNode contains a list of constant
1879 /// integers which are the source locations of the start of each line in the
1880 /// asm.
1881 static llvm::MDNode *getAsmSrcLocInfo(const StringLiteral *Str,
1882                                       CodeGenFunction &CGF) {
1883   SmallVector<llvm::Metadata *, 8> Locs;
1884   // Add the location of the first line to the MDNode.
1885   Locs.push_back(llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
1886       CGF.Int32Ty, Str->getBeginLoc().getRawEncoding())));
1887   StringRef StrVal = Str->getString();
1888   if (!StrVal.empty()) {
1889     const SourceManager &SM = CGF.CGM.getContext().getSourceManager();
1890     const LangOptions &LangOpts = CGF.CGM.getLangOpts();
1891     unsigned StartToken = 0;
1892     unsigned ByteOffset = 0;
1893 
1894     // Add the location of the start of each subsequent line of the asm to the
1895     // MDNode.
1896     for (unsigned i = 0, e = StrVal.size() - 1; i != e; ++i) {
1897       if (StrVal[i] != '\n') continue;
1898       SourceLocation LineLoc = Str->getLocationOfByte(
1899           i + 1, SM, LangOpts, CGF.getTarget(), &StartToken, &ByteOffset);
1900       Locs.push_back(llvm::ConstantAsMetadata::get(
1901           llvm::ConstantInt::get(CGF.Int32Ty, LineLoc.getRawEncoding())));
1902     }
1903   }
1904 
1905   return llvm::MDNode::get(CGF.getLLVMContext(), Locs);
1906 }
1907 
1908 static void UpdateAsmCallInst(llvm::CallBase &Result, bool HasSideEffect,
1909                               bool ReadOnly, bool ReadNone, const AsmStmt &S,
1910                               const std::vector<llvm::Type *> &ResultRegTypes,
1911                               CodeGenFunction &CGF,
1912                               std::vector<llvm::Value *> &RegResults) {
1913   Result.addAttribute(llvm::AttributeList::FunctionIndex,
1914                       llvm::Attribute::NoUnwind);
1915   // Attach readnone and readonly attributes.
1916   if (!HasSideEffect) {
1917     if (ReadNone)
1918       Result.addAttribute(llvm::AttributeList::FunctionIndex,
1919                           llvm::Attribute::ReadNone);
1920     else if (ReadOnly)
1921       Result.addAttribute(llvm::AttributeList::FunctionIndex,
1922                           llvm::Attribute::ReadOnly);
1923   }
1924 
1925   // Slap the source location of the inline asm into a !srcloc metadata on the
1926   // call.
1927   if (const auto *gccAsmStmt = dyn_cast<GCCAsmStmt>(&S))
1928     Result.setMetadata("srcloc",
1929                        getAsmSrcLocInfo(gccAsmStmt->getAsmString(), CGF));
1930   else {
1931     // At least put the line number on MS inline asm blobs.
1932     llvm::Constant *Loc = llvm::ConstantInt::get(CGF.Int32Ty,
1933                                         S.getAsmLoc().getRawEncoding());
1934     Result.setMetadata("srcloc",
1935                        llvm::MDNode::get(CGF.getLLVMContext(),
1936                                          llvm::ConstantAsMetadata::get(Loc)));
1937   }
1938 
1939   if (CGF.getLangOpts().assumeFunctionsAreConvergent())
1940     // Conservatively, mark all inline asm blocks in CUDA or OpenCL as
1941     // convergent (meaning, they may call an intrinsically convergent op, such
1942     // as bar.sync, and so can't have certain optimizations applied around
1943     // them).
1944     Result.addAttribute(llvm::AttributeList::FunctionIndex,
1945                         llvm::Attribute::Convergent);
1946   // Extract all of the register value results from the asm.
1947   if (ResultRegTypes.size() == 1) {
1948     RegResults.push_back(&Result);
1949   } else {
1950     for (unsigned i = 0, e = ResultRegTypes.size(); i != e; ++i) {
1951       llvm::Value *Tmp = CGF.Builder.CreateExtractValue(&Result, i, "asmresult");
1952       RegResults.push_back(Tmp);
1953     }
1954   }
1955 }
1956 
1957 void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {
1958   // Assemble the final asm string.
1959   std::string AsmString = S.generateAsmString(getContext());
1960 
1961   // Get all the output and input constraints together.
1962   SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
1963   SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
1964 
1965   for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) {
1966     StringRef Name;
1967     if (const GCCAsmStmt *GAS = dyn_cast<GCCAsmStmt>(&S))
1968       Name = GAS->getOutputName(i);
1969     TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), Name);
1970     bool IsValid = getTarget().validateOutputConstraint(Info); (void)IsValid;
1971     assert(IsValid && "Failed to parse output constraint");
1972     OutputConstraintInfos.push_back(Info);
1973   }
1974 
1975   for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) {
1976     StringRef Name;
1977     if (const GCCAsmStmt *GAS = dyn_cast<GCCAsmStmt>(&S))
1978       Name = GAS->getInputName(i);
1979     TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), Name);
1980     bool IsValid =
1981       getTarget().validateInputConstraint(OutputConstraintInfos, Info);
1982     assert(IsValid && "Failed to parse input constraint"); (void)IsValid;
1983     InputConstraintInfos.push_back(Info);
1984   }
1985 
1986   std::string Constraints;
1987 
1988   std::vector<LValue> ResultRegDests;
1989   std::vector<QualType> ResultRegQualTys;
1990   std::vector<llvm::Type *> ResultRegTypes;
1991   std::vector<llvm::Type *> ResultTruncRegTypes;
1992   std::vector<llvm::Type *> ArgTypes;
1993   std::vector<llvm::Value*> Args;
1994   llvm::BitVector ResultTypeRequiresCast;
1995 
1996   // Keep track of inout constraints.
1997   std::string InOutConstraints;
1998   std::vector<llvm::Value*> InOutArgs;
1999   std::vector<llvm::Type*> InOutArgTypes;
2000 
2001   // Keep track of out constraints for tied input operand.
2002   std::vector<std::string> OutputConstraints;
2003 
2004   // An inline asm can be marked readonly if it meets the following conditions:
2005   //  - it doesn't have any sideeffects
2006   //  - it doesn't clobber memory
2007   //  - it doesn't return a value by-reference
2008   // It can be marked readnone if it doesn't have any input memory constraints
2009   // in addition to meeting the conditions listed above.
2010   bool ReadOnly = true, ReadNone = true;
2011 
2012   for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) {
2013     TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];
2014 
2015     // Simplify the output constraint.
2016     std::string OutputConstraint(S.getOutputConstraint(i));
2017     OutputConstraint = SimplifyConstraint(OutputConstraint.c_str() + 1,
2018                                           getTarget(), &OutputConstraintInfos);
2019 
2020     const Expr *OutExpr = S.getOutputExpr(i);
2021     OutExpr = OutExpr->IgnoreParenNoopCasts(getContext());
2022 
2023     OutputConstraint = AddVariableConstraints(OutputConstraint, *OutExpr,
2024                                               getTarget(), CGM, S,
2025                                               Info.earlyClobber());
2026     OutputConstraints.push_back(OutputConstraint);
2027     LValue Dest = EmitLValue(OutExpr);
2028     if (!Constraints.empty())
2029       Constraints += ',';
2030 
2031     // If this is a register output, then make the inline asm return it
2032     // by-value.  If this is a memory result, return the value by-reference.
2033     bool isScalarizableAggregate =
2034         hasAggregateEvaluationKind(OutExpr->getType());
2035     if (!Info.allowsMemory() && (hasScalarEvaluationKind(OutExpr->getType()) ||
2036                                  isScalarizableAggregate)) {
2037       Constraints += "=" + OutputConstraint;
2038       ResultRegQualTys.push_back(OutExpr->getType());
2039       ResultRegDests.push_back(Dest);
2040       ResultTruncRegTypes.push_back(ConvertTypeForMem(OutExpr->getType()));
2041       if (Info.allowsRegister() && isScalarizableAggregate) {
2042         ResultTypeRequiresCast.push_back(true);
2043         unsigned Size = getContext().getTypeSize(OutExpr->getType());
2044         llvm::Type *ConvTy = llvm::IntegerType::get(getLLVMContext(), Size);
2045         ResultRegTypes.push_back(ConvTy);
2046       } else {
2047         ResultTypeRequiresCast.push_back(false);
2048         ResultRegTypes.push_back(ResultTruncRegTypes.back());
2049       }
2050       // If this output is tied to an input, and if the input is larger, then
2051       // we need to set the actual result type of the inline asm node to be the
2052       // same as the input type.
2053       if (Info.hasMatchingInput()) {
2054         unsigned InputNo;
2055         for (InputNo = 0; InputNo != S.getNumInputs(); ++InputNo) {
2056           TargetInfo::ConstraintInfo &Input = InputConstraintInfos[InputNo];
2057           if (Input.hasTiedOperand() && Input.getTiedOperand() == i)
2058             break;
2059         }
2060         assert(InputNo != S.getNumInputs() && "Didn't find matching input!");
2061 
2062         QualType InputTy = S.getInputExpr(InputNo)->getType();
2063         QualType OutputType = OutExpr->getType();
2064 
2065         uint64_t InputSize = getContext().getTypeSize(InputTy);
2066         if (getContext().getTypeSize(OutputType) < InputSize) {
2067           // Form the asm to return the value as a larger integer or fp type.
2068           ResultRegTypes.back() = ConvertType(InputTy);
2069         }
2070       }
2071       if (llvm::Type* AdjTy =
2072             getTargetHooks().adjustInlineAsmType(*this, OutputConstraint,
2073                                                  ResultRegTypes.back()))
2074         ResultRegTypes.back() = AdjTy;
2075       else {
2076         CGM.getDiags().Report(S.getAsmLoc(),
2077                               diag::err_asm_invalid_type_in_input)
2078             << OutExpr->getType() << OutputConstraint;
2079       }
2080 
2081       // Update largest vector width for any vector types.
2082       if (auto *VT = dyn_cast<llvm::VectorType>(ResultRegTypes.back()))
2083         LargestVectorWidth = std::max((uint64_t)LargestVectorWidth,
2084                                    VT->getPrimitiveSizeInBits().getFixedSize());
2085     } else {
2086       ArgTypes.push_back(Dest.getAddress().getType());
2087       Args.push_back(Dest.getPointer());
2088       Constraints += "=*";
2089       Constraints += OutputConstraint;
2090       ReadOnly = ReadNone = false;
2091     }
2092 
2093     if (Info.isReadWrite()) {
2094       InOutConstraints += ',';
2095 
2096       const Expr *InputExpr = S.getOutputExpr(i);
2097       llvm::Value *Arg = EmitAsmInputLValue(Info, Dest, InputExpr->getType(),
2098                                             InOutConstraints,
2099                                             InputExpr->getExprLoc());
2100 
2101       if (llvm::Type* AdjTy =
2102           getTargetHooks().adjustInlineAsmType(*this, OutputConstraint,
2103                                                Arg->getType()))
2104         Arg = Builder.CreateBitCast(Arg, AdjTy);
2105 
2106       // Update largest vector width for any vector types.
2107       if (auto *VT = dyn_cast<llvm::VectorType>(Arg->getType()))
2108         LargestVectorWidth = std::max((uint64_t)LargestVectorWidth,
2109                                    VT->getPrimitiveSizeInBits().getFixedSize());
2110       if (Info.allowsRegister())
2111         InOutConstraints += llvm::utostr(i);
2112       else
2113         InOutConstraints += OutputConstraint;
2114 
2115       InOutArgTypes.push_back(Arg->getType());
2116       InOutArgs.push_back(Arg);
2117     }
2118   }
2119 
2120   // If this is a Microsoft-style asm blob, store the return registers (EAX:EDX)
2121   // to the return value slot. Only do this when returning in registers.
2122   if (isa<MSAsmStmt>(&S)) {
2123     const ABIArgInfo &RetAI = CurFnInfo->getReturnInfo();
2124     if (RetAI.isDirect() || RetAI.isExtend()) {
2125       // Make a fake lvalue for the return value slot.
2126       LValue ReturnSlot = MakeAddrLValue(ReturnValue, FnRetTy);
2127       CGM.getTargetCodeGenInfo().addReturnRegisterOutputs(
2128           *this, ReturnSlot, Constraints, ResultRegTypes, ResultTruncRegTypes,
2129           ResultRegDests, AsmString, S.getNumOutputs());
2130       SawAsmBlock = true;
2131     }
2132   }
2133 
2134   for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) {
2135     const Expr *InputExpr = S.getInputExpr(i);
2136 
2137     TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
2138 
2139     if (Info.allowsMemory())
2140       ReadNone = false;
2141 
2142     if (!Constraints.empty())
2143       Constraints += ',';
2144 
2145     // Simplify the input constraint.
2146     std::string InputConstraint(S.getInputConstraint(i));
2147     InputConstraint = SimplifyConstraint(InputConstraint.c_str(), getTarget(),
2148                                          &OutputConstraintInfos);
2149 
2150     InputConstraint = AddVariableConstraints(
2151         InputConstraint, *InputExpr->IgnoreParenNoopCasts(getContext()),
2152         getTarget(), CGM, S, false /* No EarlyClobber */);
2153 
2154     std::string ReplaceConstraint (InputConstraint);
2155     llvm::Value *Arg = EmitAsmInput(Info, InputExpr, Constraints);
2156 
2157     // If this input argument is tied to a larger output result, extend the
2158     // input to be the same size as the output.  The LLVM backend wants to see
2159     // the input and output of a matching constraint be the same size.  Note
2160     // that GCC does not define what the top bits are here.  We use zext because
2161     // that is usually cheaper, but LLVM IR should really get an anyext someday.
2162     if (Info.hasTiedOperand()) {
2163       unsigned Output = Info.getTiedOperand();
2164       QualType OutputType = S.getOutputExpr(Output)->getType();
2165       QualType InputTy = InputExpr->getType();
2166 
2167       if (getContext().getTypeSize(OutputType) >
2168           getContext().getTypeSize(InputTy)) {
2169         // Use ptrtoint as appropriate so that we can do our extension.
2170         if (isa<llvm::PointerType>(Arg->getType()))
2171           Arg = Builder.CreatePtrToInt(Arg, IntPtrTy);
2172         llvm::Type *OutputTy = ConvertType(OutputType);
2173         if (isa<llvm::IntegerType>(OutputTy))
2174           Arg = Builder.CreateZExt(Arg, OutputTy);
2175         else if (isa<llvm::PointerType>(OutputTy))
2176           Arg = Builder.CreateZExt(Arg, IntPtrTy);
2177         else {
2178           assert(OutputTy->isFloatingPointTy() && "Unexpected output type");
2179           Arg = Builder.CreateFPExt(Arg, OutputTy);
2180         }
2181       }
2182       // Deal with the tied operands' constraint code in adjustInlineAsmType.
2183       ReplaceConstraint = OutputConstraints[Output];
2184     }
2185     if (llvm::Type* AdjTy =
2186           getTargetHooks().adjustInlineAsmType(*this, ReplaceConstraint,
2187                                                    Arg->getType()))
2188       Arg = Builder.CreateBitCast(Arg, AdjTy);
2189     else
2190       CGM.getDiags().Report(S.getAsmLoc(), diag::err_asm_invalid_type_in_input)
2191           << InputExpr->getType() << InputConstraint;
2192 
2193     // Update largest vector width for any vector types.
2194     if (auto *VT = dyn_cast<llvm::VectorType>(Arg->getType()))
2195       LargestVectorWidth = std::max((uint64_t)LargestVectorWidth,
2196                                    VT->getPrimitiveSizeInBits().getFixedSize());
2197 
2198     ArgTypes.push_back(Arg->getType());
2199     Args.push_back(Arg);
2200     Constraints += InputConstraint;
2201   }
2202 
2203   // Append the "input" part of inout constraints last.
2204   for (unsigned i = 0, e = InOutArgs.size(); i != e; i++) {
2205     ArgTypes.push_back(InOutArgTypes[i]);
2206     Args.push_back(InOutArgs[i]);
2207   }
2208   Constraints += InOutConstraints;
2209 
2210   // Labels
2211   SmallVector<llvm::BasicBlock *, 16> Transfer;
2212   llvm::BasicBlock *Fallthrough = nullptr;
2213   bool IsGCCAsmGoto = false;
2214   if (const auto *GS =  dyn_cast<GCCAsmStmt>(&S)) {
2215     IsGCCAsmGoto = GS->isAsmGoto();
2216     if (IsGCCAsmGoto) {
2217       for (auto *E : GS->labels()) {
2218         JumpDest Dest = getJumpDestForLabel(E->getLabel());
2219         Transfer.push_back(Dest.getBlock());
2220         llvm::BlockAddress *BA =
2221             llvm::BlockAddress::get(CurFn, Dest.getBlock());
2222         Args.push_back(BA);
2223         ArgTypes.push_back(BA->getType());
2224         if (!Constraints.empty())
2225           Constraints += ',';
2226         Constraints += 'X';
2227       }
2228       StringRef Name = "asm.fallthrough";
2229       Fallthrough = createBasicBlock(Name);
2230     }
2231   }
2232 
2233   // Clobbers
2234   for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) {
2235     StringRef Clobber = S.getClobber(i);
2236 
2237     if (Clobber == "memory")
2238       ReadOnly = ReadNone = false;
2239     else if (Clobber != "cc")
2240       Clobber = getTarget().getNormalizedGCCRegisterName(Clobber);
2241 
2242     if (!Constraints.empty())
2243       Constraints += ',';
2244 
2245     Constraints += "~{";
2246     Constraints += Clobber;
2247     Constraints += '}';
2248   }
2249 
2250   // Add machine specific clobbers
2251   std::string MachineClobbers = getTarget().getClobbers();
2252   if (!MachineClobbers.empty()) {
2253     if (!Constraints.empty())
2254       Constraints += ',';
2255     Constraints += MachineClobbers;
2256   }
2257 
2258   llvm::Type *ResultType;
2259   if (ResultRegTypes.empty())
2260     ResultType = VoidTy;
2261   else if (ResultRegTypes.size() == 1)
2262     ResultType = ResultRegTypes[0];
2263   else
2264     ResultType = llvm::StructType::get(getLLVMContext(), ResultRegTypes);
2265 
2266   llvm::FunctionType *FTy =
2267     llvm::FunctionType::get(ResultType, ArgTypes, false);
2268 
2269   bool HasSideEffect = S.isVolatile() || S.getNumOutputs() == 0;
2270   llvm::InlineAsm::AsmDialect AsmDialect = isa<MSAsmStmt>(&S) ?
2271     llvm::InlineAsm::AD_Intel : llvm::InlineAsm::AD_ATT;
2272   llvm::InlineAsm *IA =
2273     llvm::InlineAsm::get(FTy, AsmString, Constraints, HasSideEffect,
2274                          /* IsAlignStack */ false, AsmDialect);
2275   std::vector<llvm::Value*> RegResults;
2276   if (IsGCCAsmGoto) {
2277     llvm::CallBrInst *Result =
2278         Builder.CreateCallBr(IA, Fallthrough, Transfer, Args);
2279     UpdateAsmCallInst(cast<llvm::CallBase>(*Result), HasSideEffect, ReadOnly,
2280                       ReadNone, S, ResultRegTypes, *this, RegResults);
2281     EmitBlock(Fallthrough);
2282   } else {
2283     llvm::CallInst *Result =
2284         Builder.CreateCall(IA, Args, getBundlesForFunclet(IA));
2285     UpdateAsmCallInst(cast<llvm::CallBase>(*Result), HasSideEffect, ReadOnly,
2286                       ReadNone, S, ResultRegTypes, *this, RegResults);
2287   }
2288 
2289   assert(RegResults.size() == ResultRegTypes.size());
2290   assert(RegResults.size() == ResultTruncRegTypes.size());
2291   assert(RegResults.size() == ResultRegDests.size());
2292   // ResultRegDests can be also populated by addReturnRegisterOutputs() above,
2293   // in which case its size may grow.
2294   assert(ResultTypeRequiresCast.size() <= ResultRegDests.size());
2295   for (unsigned i = 0, e = RegResults.size(); i != e; ++i) {
2296     llvm::Value *Tmp = RegResults[i];
2297 
2298     // If the result type of the LLVM IR asm doesn't match the result type of
2299     // the expression, do the conversion.
2300     if (ResultRegTypes[i] != ResultTruncRegTypes[i]) {
2301       llvm::Type *TruncTy = ResultTruncRegTypes[i];
2302 
2303       // Truncate the integer result to the right size, note that TruncTy can be
2304       // a pointer.
2305       if (TruncTy->isFloatingPointTy())
2306         Tmp = Builder.CreateFPTrunc(Tmp, TruncTy);
2307       else if (TruncTy->isPointerTy() && Tmp->getType()->isIntegerTy()) {
2308         uint64_t ResSize = CGM.getDataLayout().getTypeSizeInBits(TruncTy);
2309         Tmp = Builder.CreateTrunc(Tmp,
2310                    llvm::IntegerType::get(getLLVMContext(), (unsigned)ResSize));
2311         Tmp = Builder.CreateIntToPtr(Tmp, TruncTy);
2312       } else if (Tmp->getType()->isPointerTy() && TruncTy->isIntegerTy()) {
2313         uint64_t TmpSize =CGM.getDataLayout().getTypeSizeInBits(Tmp->getType());
2314         Tmp = Builder.CreatePtrToInt(Tmp,
2315                    llvm::IntegerType::get(getLLVMContext(), (unsigned)TmpSize));
2316         Tmp = Builder.CreateTrunc(Tmp, TruncTy);
2317       } else if (TruncTy->isIntegerTy()) {
2318         Tmp = Builder.CreateZExtOrTrunc(Tmp, TruncTy);
2319       } else if (TruncTy->isVectorTy()) {
2320         Tmp = Builder.CreateBitCast(Tmp, TruncTy);
2321       }
2322     }
2323 
2324     LValue Dest = ResultRegDests[i];
2325     // ResultTypeRequiresCast elements correspond to the first
2326     // ResultTypeRequiresCast.size() elements of RegResults.
2327     if ((i < ResultTypeRequiresCast.size()) && ResultTypeRequiresCast[i]) {
2328       unsigned Size = getContext().getTypeSize(ResultRegQualTys[i]);
2329       Address A = Builder.CreateBitCast(Dest.getAddress(),
2330                                         ResultRegTypes[i]->getPointerTo());
2331       QualType Ty = getContext().getIntTypeForBitwidth(Size, /*Signed*/ false);
2332       if (Ty.isNull()) {
2333         const Expr *OutExpr = S.getOutputExpr(i);
2334         CGM.Error(
2335             OutExpr->getExprLoc(),
2336             "impossible constraint in asm: can't store value into a register");
2337         return;
2338       }
2339       Dest = MakeAddrLValue(A, Ty);
2340     }
2341     EmitStoreThroughLValue(RValue::get(Tmp), Dest);
2342   }
2343 }
2344 
2345 LValue CodeGenFunction::InitCapturedStruct(const CapturedStmt &S) {
2346   const RecordDecl *RD = S.getCapturedRecordDecl();
2347   QualType RecordTy = getContext().getRecordType(RD);
2348 
2349   // Initialize the captured struct.
2350   LValue SlotLV =
2351     MakeAddrLValue(CreateMemTemp(RecordTy, "agg.captured"), RecordTy);
2352 
2353   RecordDecl::field_iterator CurField = RD->field_begin();
2354   for (CapturedStmt::const_capture_init_iterator I = S.capture_init_begin(),
2355                                                  E = S.capture_init_end();
2356        I != E; ++I, ++CurField) {
2357     LValue LV = EmitLValueForFieldInitialization(SlotLV, *CurField);
2358     if (CurField->hasCapturedVLAType()) {
2359       auto VAT = CurField->getCapturedVLAType();
2360       EmitStoreThroughLValue(RValue::get(VLASizeMap[VAT->getSizeExpr()]), LV);
2361     } else {
2362       EmitInitializerForField(*CurField, LV, *I);
2363     }
2364   }
2365 
2366   return SlotLV;
2367 }
2368 
2369 /// Generate an outlined function for the body of a CapturedStmt, store any
2370 /// captured variables into the captured struct, and call the outlined function.
2371 llvm::Function *
2372 CodeGenFunction::EmitCapturedStmt(const CapturedStmt &S, CapturedRegionKind K) {
2373   LValue CapStruct = InitCapturedStruct(S);
2374 
2375   // Emit the CapturedDecl
2376   CodeGenFunction CGF(CGM, true);
2377   CGCapturedStmtRAII CapInfoRAII(CGF, new CGCapturedStmtInfo(S, K));
2378   llvm::Function *F = CGF.GenerateCapturedStmtFunction(S);
2379   delete CGF.CapturedStmtInfo;
2380 
2381   // Emit call to the helper function.
2382   EmitCallOrInvoke(F, CapStruct.getPointer());
2383 
2384   return F;
2385 }
2386 
2387 Address CodeGenFunction::GenerateCapturedStmtArgument(const CapturedStmt &S) {
2388   LValue CapStruct = InitCapturedStruct(S);
2389   return CapStruct.getAddress();
2390 }
2391 
2392 /// Creates the outlined function for a CapturedStmt.
2393 llvm::Function *
2394 CodeGenFunction::GenerateCapturedStmtFunction(const CapturedStmt &S) {
2395   assert(CapturedStmtInfo &&
2396     "CapturedStmtInfo should be set when generating the captured function");
2397   const CapturedDecl *CD = S.getCapturedDecl();
2398   const RecordDecl *RD = S.getCapturedRecordDecl();
2399   SourceLocation Loc = S.getBeginLoc();
2400   assert(CD->hasBody() && "missing CapturedDecl body");
2401 
2402   // Build the argument list.
2403   ASTContext &Ctx = CGM.getContext();
2404   FunctionArgList Args;
2405   Args.append(CD->param_begin(), CD->param_end());
2406 
2407   // Create the function declaration.
2408   const CGFunctionInfo &FuncInfo =
2409     CGM.getTypes().arrangeBuiltinFunctionDeclaration(Ctx.VoidTy, Args);
2410   llvm::FunctionType *FuncLLVMTy = CGM.getTypes().GetFunctionType(FuncInfo);
2411 
2412   llvm::Function *F =
2413     llvm::Function::Create(FuncLLVMTy, llvm::GlobalValue::InternalLinkage,
2414                            CapturedStmtInfo->getHelperName(), &CGM.getModule());
2415   CGM.SetInternalFunctionAttributes(CD, F, FuncInfo);
2416   if (CD->isNothrow())
2417     F->addFnAttr(llvm::Attribute::NoUnwind);
2418 
2419   // Generate the function.
2420   StartFunction(CD, Ctx.VoidTy, F, FuncInfo, Args, CD->getLocation(),
2421                 CD->getBody()->getBeginLoc());
2422   // Set the context parameter in CapturedStmtInfo.
2423   Address DeclPtr = GetAddrOfLocalVar(CD->getContextParam());
2424   CapturedStmtInfo->setContextValue(Builder.CreateLoad(DeclPtr));
2425 
2426   // Initialize variable-length arrays.
2427   LValue Base = MakeNaturalAlignAddrLValue(CapturedStmtInfo->getContextValue(),
2428                                            Ctx.getTagDeclType(RD));
2429   for (auto *FD : RD->fields()) {
2430     if (FD->hasCapturedVLAType()) {
2431       auto *ExprArg =
2432           EmitLoadOfLValue(EmitLValueForField(Base, FD), S.getBeginLoc())
2433               .getScalarVal();
2434       auto VAT = FD->getCapturedVLAType();
2435       VLASizeMap[VAT->getSizeExpr()] = ExprArg;
2436     }
2437   }
2438 
2439   // If 'this' is captured, load it into CXXThisValue.
2440   if (CapturedStmtInfo->isCXXThisExprCaptured()) {
2441     FieldDecl *FD = CapturedStmtInfo->getThisFieldDecl();
2442     LValue ThisLValue = EmitLValueForField(Base, FD);
2443     CXXThisValue = EmitLoadOfLValue(ThisLValue, Loc).getScalarVal();
2444   }
2445 
2446   PGO.assignRegionCounters(GlobalDecl(CD), F);
2447   CapturedStmtInfo->EmitBody(*this, CD->getBody());
2448   FinishFunction(CD->getBodyRBrace());
2449 
2450   return F;
2451 }
2452