xref: /freebsd/contrib/llvm-project/clang/lib/CodeGen/CGStmt.cpp (revision 0d8fe2373503aeac48492f28073049a8bfa4feb5)
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 "CGDebugInfo.h"
14 #include "CGOpenMPRuntime.h"
15 #include "CodeGenFunction.h"
16 #include "CodeGenModule.h"
17 #include "TargetInfo.h"
18 #include "clang/AST/Attr.h"
19 #include "clang/AST/StmtVisitor.h"
20 #include "clang/Basic/Builtins.h"
21 #include "clang/Basic/DiagnosticSema.h"
22 #include "clang/Basic/PrettyStackTrace.h"
23 #include "clang/Basic/SourceManager.h"
24 #include "clang/Basic/TargetInfo.h"
25 #include "llvm/ADT/SmallSet.h"
26 #include "llvm/ADT/StringExtras.h"
27 #include "llvm/IR/DataLayout.h"
28 #include "llvm/IR/InlineAsm.h"
29 #include "llvm/IR/Intrinsics.h"
30 #include "llvm/IR/MDBuilder.h"
31 #include "llvm/Support/SaveAndRestore.h"
32 
33 using namespace clang;
34 using namespace CodeGen;
35 
36 //===----------------------------------------------------------------------===//
37 //                              Statement Emission
38 //===----------------------------------------------------------------------===//
39 
40 void CodeGenFunction::EmitStopPoint(const Stmt *S) {
41   if (CGDebugInfo *DI = getDebugInfo()) {
42     SourceLocation Loc;
43     Loc = S->getBeginLoc();
44     DI->EmitLocation(Builder, Loc);
45 
46     LastStopPoint = Loc;
47   }
48 }
49 
50 void CodeGenFunction::EmitStmt(const Stmt *S, ArrayRef<const Attr *> Attrs) {
51   assert(S && "Null statement?");
52   PGO.setCurrentStmt(S);
53 
54   // These statements have their own debug info handling.
55   if (EmitSimpleStmt(S, Attrs))
56     return;
57 
58   // Check if we are generating unreachable code.
59   if (!HaveInsertPoint()) {
60     // If so, and the statement doesn't contain a label, then we do not need to
61     // generate actual code. This is safe because (1) the current point is
62     // unreachable, so we don't need to execute the code, and (2) we've already
63     // handled the statements which update internal data structures (like the
64     // local variable map) which could be used by subsequent statements.
65     if (!ContainsLabel(S)) {
66       // Verify that any decl statements were handled as simple, they may be in
67       // scope of subsequent reachable statements.
68       assert(!isa<DeclStmt>(*S) && "Unexpected DeclStmt!");
69       return;
70     }
71 
72     // Otherwise, make a new block to hold the code.
73     EnsureInsertPoint();
74   }
75 
76   // Generate a stoppoint if we are emitting debug info.
77   EmitStopPoint(S);
78 
79   // Ignore all OpenMP directives except for simd if OpenMP with Simd is
80   // enabled.
81   if (getLangOpts().OpenMP && getLangOpts().OpenMPSimd) {
82     if (const auto *D = dyn_cast<OMPExecutableDirective>(S)) {
83       EmitSimpleOMPExecutableDirective(*D);
84       return;
85     }
86   }
87 
88   switch (S->getStmtClass()) {
89   case Stmt::NoStmtClass:
90   case Stmt::CXXCatchStmtClass:
91   case Stmt::SEHExceptStmtClass:
92   case Stmt::SEHFinallyStmtClass:
93   case Stmt::MSDependentExistsStmtClass:
94     llvm_unreachable("invalid statement class to emit generically");
95   case Stmt::NullStmtClass:
96   case Stmt::CompoundStmtClass:
97   case Stmt::DeclStmtClass:
98   case Stmt::LabelStmtClass:
99   case Stmt::AttributedStmtClass:
100   case Stmt::GotoStmtClass:
101   case Stmt::BreakStmtClass:
102   case Stmt::ContinueStmtClass:
103   case Stmt::DefaultStmtClass:
104   case Stmt::CaseStmtClass:
105   case Stmt::SEHLeaveStmtClass:
106     llvm_unreachable("should have emitted these statements as simple");
107 
108 #define STMT(Type, Base)
109 #define ABSTRACT_STMT(Op)
110 #define EXPR(Type, Base) \
111   case Stmt::Type##Class:
112 #include "clang/AST/StmtNodes.inc"
113   {
114     // Remember the block we came in on.
115     llvm::BasicBlock *incoming = Builder.GetInsertBlock();
116     assert(incoming && "expression emission must have an insertion point");
117 
118     EmitIgnoredExpr(cast<Expr>(S));
119 
120     llvm::BasicBlock *outgoing = Builder.GetInsertBlock();
121     assert(outgoing && "expression emission cleared block!");
122 
123     // The expression emitters assume (reasonably!) that the insertion
124     // point is always set.  To maintain that, the call-emission code
125     // for noreturn functions has to enter a new block with no
126     // predecessors.  We want to kill that block and mark the current
127     // insertion point unreachable in the common case of a call like
128     // "exit();".  Since expression emission doesn't otherwise create
129     // blocks with no predecessors, we can just test for that.
130     // However, we must be careful not to do this to our incoming
131     // block, because *statement* emission does sometimes create
132     // reachable blocks which will have no predecessors until later in
133     // the function.  This occurs with, e.g., labels that are not
134     // reachable by fallthrough.
135     if (incoming != outgoing && outgoing->use_empty()) {
136       outgoing->eraseFromParent();
137       Builder.ClearInsertionPoint();
138     }
139     break;
140   }
141 
142   case Stmt::IndirectGotoStmtClass:
143     EmitIndirectGotoStmt(cast<IndirectGotoStmt>(*S)); break;
144 
145   case Stmt::IfStmtClass:      EmitIfStmt(cast<IfStmt>(*S));              break;
146   case Stmt::WhileStmtClass:   EmitWhileStmt(cast<WhileStmt>(*S), Attrs); break;
147   case Stmt::DoStmtClass:      EmitDoStmt(cast<DoStmt>(*S), Attrs);       break;
148   case Stmt::ForStmtClass:     EmitForStmt(cast<ForStmt>(*S), Attrs);     break;
149 
150   case Stmt::ReturnStmtClass:  EmitReturnStmt(cast<ReturnStmt>(*S));      break;
151 
152   case Stmt::SwitchStmtClass:  EmitSwitchStmt(cast<SwitchStmt>(*S));      break;
153   case Stmt::GCCAsmStmtClass:  // Intentional fall-through.
154   case Stmt::MSAsmStmtClass:   EmitAsmStmt(cast<AsmStmt>(*S));            break;
155   case Stmt::CoroutineBodyStmtClass:
156     EmitCoroutineBody(cast<CoroutineBodyStmt>(*S));
157     break;
158   case Stmt::CoreturnStmtClass:
159     EmitCoreturnStmt(cast<CoreturnStmt>(*S));
160     break;
161   case Stmt::CapturedStmtClass: {
162     const CapturedStmt *CS = cast<CapturedStmt>(S);
163     EmitCapturedStmt(*CS, CS->getCapturedRegionKind());
164     }
165     break;
166   case Stmt::ObjCAtTryStmtClass:
167     EmitObjCAtTryStmt(cast<ObjCAtTryStmt>(*S));
168     break;
169   case Stmt::ObjCAtCatchStmtClass:
170     llvm_unreachable(
171                     "@catch statements should be handled by EmitObjCAtTryStmt");
172   case Stmt::ObjCAtFinallyStmtClass:
173     llvm_unreachable(
174                   "@finally statements should be handled by EmitObjCAtTryStmt");
175   case Stmt::ObjCAtThrowStmtClass:
176     EmitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(*S));
177     break;
178   case Stmt::ObjCAtSynchronizedStmtClass:
179     EmitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(*S));
180     break;
181   case Stmt::ObjCForCollectionStmtClass:
182     EmitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(*S));
183     break;
184   case Stmt::ObjCAutoreleasePoolStmtClass:
185     EmitObjCAutoreleasePoolStmt(cast<ObjCAutoreleasePoolStmt>(*S));
186     break;
187 
188   case Stmt::CXXTryStmtClass:
189     EmitCXXTryStmt(cast<CXXTryStmt>(*S));
190     break;
191   case Stmt::CXXForRangeStmtClass:
192     EmitCXXForRangeStmt(cast<CXXForRangeStmt>(*S), Attrs);
193     break;
194   case Stmt::SEHTryStmtClass:
195     EmitSEHTryStmt(cast<SEHTryStmt>(*S));
196     break;
197   case Stmt::OMPParallelDirectiveClass:
198     EmitOMPParallelDirective(cast<OMPParallelDirective>(*S));
199     break;
200   case Stmt::OMPSimdDirectiveClass:
201     EmitOMPSimdDirective(cast<OMPSimdDirective>(*S));
202     break;
203   case Stmt::OMPForDirectiveClass:
204     EmitOMPForDirective(cast<OMPForDirective>(*S));
205     break;
206   case Stmt::OMPForSimdDirectiveClass:
207     EmitOMPForSimdDirective(cast<OMPForSimdDirective>(*S));
208     break;
209   case Stmt::OMPSectionsDirectiveClass:
210     EmitOMPSectionsDirective(cast<OMPSectionsDirective>(*S));
211     break;
212   case Stmt::OMPSectionDirectiveClass:
213     EmitOMPSectionDirective(cast<OMPSectionDirective>(*S));
214     break;
215   case Stmt::OMPSingleDirectiveClass:
216     EmitOMPSingleDirective(cast<OMPSingleDirective>(*S));
217     break;
218   case Stmt::OMPMasterDirectiveClass:
219     EmitOMPMasterDirective(cast<OMPMasterDirective>(*S));
220     break;
221   case Stmt::OMPCriticalDirectiveClass:
222     EmitOMPCriticalDirective(cast<OMPCriticalDirective>(*S));
223     break;
224   case Stmt::OMPParallelForDirectiveClass:
225     EmitOMPParallelForDirective(cast<OMPParallelForDirective>(*S));
226     break;
227   case Stmt::OMPParallelForSimdDirectiveClass:
228     EmitOMPParallelForSimdDirective(cast<OMPParallelForSimdDirective>(*S));
229     break;
230   case Stmt::OMPParallelMasterDirectiveClass:
231     EmitOMPParallelMasterDirective(cast<OMPParallelMasterDirective>(*S));
232     break;
233   case Stmt::OMPParallelSectionsDirectiveClass:
234     EmitOMPParallelSectionsDirective(cast<OMPParallelSectionsDirective>(*S));
235     break;
236   case Stmt::OMPTaskDirectiveClass:
237     EmitOMPTaskDirective(cast<OMPTaskDirective>(*S));
238     break;
239   case Stmt::OMPTaskyieldDirectiveClass:
240     EmitOMPTaskyieldDirective(cast<OMPTaskyieldDirective>(*S));
241     break;
242   case Stmt::OMPBarrierDirectiveClass:
243     EmitOMPBarrierDirective(cast<OMPBarrierDirective>(*S));
244     break;
245   case Stmt::OMPTaskwaitDirectiveClass:
246     EmitOMPTaskwaitDirective(cast<OMPTaskwaitDirective>(*S));
247     break;
248   case Stmt::OMPTaskgroupDirectiveClass:
249     EmitOMPTaskgroupDirective(cast<OMPTaskgroupDirective>(*S));
250     break;
251   case Stmt::OMPFlushDirectiveClass:
252     EmitOMPFlushDirective(cast<OMPFlushDirective>(*S));
253     break;
254   case Stmt::OMPDepobjDirectiveClass:
255     EmitOMPDepobjDirective(cast<OMPDepobjDirective>(*S));
256     break;
257   case Stmt::OMPScanDirectiveClass:
258     EmitOMPScanDirective(cast<OMPScanDirective>(*S));
259     break;
260   case Stmt::OMPOrderedDirectiveClass:
261     EmitOMPOrderedDirective(cast<OMPOrderedDirective>(*S));
262     break;
263   case Stmt::OMPAtomicDirectiveClass:
264     EmitOMPAtomicDirective(cast<OMPAtomicDirective>(*S));
265     break;
266   case Stmt::OMPTargetDirectiveClass:
267     EmitOMPTargetDirective(cast<OMPTargetDirective>(*S));
268     break;
269   case Stmt::OMPTeamsDirectiveClass:
270     EmitOMPTeamsDirective(cast<OMPTeamsDirective>(*S));
271     break;
272   case Stmt::OMPCancellationPointDirectiveClass:
273     EmitOMPCancellationPointDirective(cast<OMPCancellationPointDirective>(*S));
274     break;
275   case Stmt::OMPCancelDirectiveClass:
276     EmitOMPCancelDirective(cast<OMPCancelDirective>(*S));
277     break;
278   case Stmt::OMPTargetDataDirectiveClass:
279     EmitOMPTargetDataDirective(cast<OMPTargetDataDirective>(*S));
280     break;
281   case Stmt::OMPTargetEnterDataDirectiveClass:
282     EmitOMPTargetEnterDataDirective(cast<OMPTargetEnterDataDirective>(*S));
283     break;
284   case Stmt::OMPTargetExitDataDirectiveClass:
285     EmitOMPTargetExitDataDirective(cast<OMPTargetExitDataDirective>(*S));
286     break;
287   case Stmt::OMPTargetParallelDirectiveClass:
288     EmitOMPTargetParallelDirective(cast<OMPTargetParallelDirective>(*S));
289     break;
290   case Stmt::OMPTargetParallelForDirectiveClass:
291     EmitOMPTargetParallelForDirective(cast<OMPTargetParallelForDirective>(*S));
292     break;
293   case Stmt::OMPTaskLoopDirectiveClass:
294     EmitOMPTaskLoopDirective(cast<OMPTaskLoopDirective>(*S));
295     break;
296   case Stmt::OMPTaskLoopSimdDirectiveClass:
297     EmitOMPTaskLoopSimdDirective(cast<OMPTaskLoopSimdDirective>(*S));
298     break;
299   case Stmt::OMPMasterTaskLoopDirectiveClass:
300     EmitOMPMasterTaskLoopDirective(cast<OMPMasterTaskLoopDirective>(*S));
301     break;
302   case Stmt::OMPMasterTaskLoopSimdDirectiveClass:
303     EmitOMPMasterTaskLoopSimdDirective(
304         cast<OMPMasterTaskLoopSimdDirective>(*S));
305     break;
306   case Stmt::OMPParallelMasterTaskLoopDirectiveClass:
307     EmitOMPParallelMasterTaskLoopDirective(
308         cast<OMPParallelMasterTaskLoopDirective>(*S));
309     break;
310   case Stmt::OMPParallelMasterTaskLoopSimdDirectiveClass:
311     EmitOMPParallelMasterTaskLoopSimdDirective(
312         cast<OMPParallelMasterTaskLoopSimdDirective>(*S));
313     break;
314   case Stmt::OMPDistributeDirectiveClass:
315     EmitOMPDistributeDirective(cast<OMPDistributeDirective>(*S));
316     break;
317   case Stmt::OMPTargetUpdateDirectiveClass:
318     EmitOMPTargetUpdateDirective(cast<OMPTargetUpdateDirective>(*S));
319     break;
320   case Stmt::OMPDistributeParallelForDirectiveClass:
321     EmitOMPDistributeParallelForDirective(
322         cast<OMPDistributeParallelForDirective>(*S));
323     break;
324   case Stmt::OMPDistributeParallelForSimdDirectiveClass:
325     EmitOMPDistributeParallelForSimdDirective(
326         cast<OMPDistributeParallelForSimdDirective>(*S));
327     break;
328   case Stmt::OMPDistributeSimdDirectiveClass:
329     EmitOMPDistributeSimdDirective(cast<OMPDistributeSimdDirective>(*S));
330     break;
331   case Stmt::OMPTargetParallelForSimdDirectiveClass:
332     EmitOMPTargetParallelForSimdDirective(
333         cast<OMPTargetParallelForSimdDirective>(*S));
334     break;
335   case Stmt::OMPTargetSimdDirectiveClass:
336     EmitOMPTargetSimdDirective(cast<OMPTargetSimdDirective>(*S));
337     break;
338   case Stmt::OMPTeamsDistributeDirectiveClass:
339     EmitOMPTeamsDistributeDirective(cast<OMPTeamsDistributeDirective>(*S));
340     break;
341   case Stmt::OMPTeamsDistributeSimdDirectiveClass:
342     EmitOMPTeamsDistributeSimdDirective(
343         cast<OMPTeamsDistributeSimdDirective>(*S));
344     break;
345   case Stmt::OMPTeamsDistributeParallelForSimdDirectiveClass:
346     EmitOMPTeamsDistributeParallelForSimdDirective(
347         cast<OMPTeamsDistributeParallelForSimdDirective>(*S));
348     break;
349   case Stmt::OMPTeamsDistributeParallelForDirectiveClass:
350     EmitOMPTeamsDistributeParallelForDirective(
351         cast<OMPTeamsDistributeParallelForDirective>(*S));
352     break;
353   case Stmt::OMPTargetTeamsDirectiveClass:
354     EmitOMPTargetTeamsDirective(cast<OMPTargetTeamsDirective>(*S));
355     break;
356   case Stmt::OMPTargetTeamsDistributeDirectiveClass:
357     EmitOMPTargetTeamsDistributeDirective(
358         cast<OMPTargetTeamsDistributeDirective>(*S));
359     break;
360   case Stmt::OMPTargetTeamsDistributeParallelForDirectiveClass:
361     EmitOMPTargetTeamsDistributeParallelForDirective(
362         cast<OMPTargetTeamsDistributeParallelForDirective>(*S));
363     break;
364   case Stmt::OMPTargetTeamsDistributeParallelForSimdDirectiveClass:
365     EmitOMPTargetTeamsDistributeParallelForSimdDirective(
366         cast<OMPTargetTeamsDistributeParallelForSimdDirective>(*S));
367     break;
368   case Stmt::OMPTargetTeamsDistributeSimdDirectiveClass:
369     EmitOMPTargetTeamsDistributeSimdDirective(
370         cast<OMPTargetTeamsDistributeSimdDirective>(*S));
371     break;
372   }
373 }
374 
375 bool CodeGenFunction::EmitSimpleStmt(const Stmt *S,
376                                      ArrayRef<const Attr *> Attrs) {
377   switch (S->getStmtClass()) {
378   default:
379     return false;
380   case Stmt::NullStmtClass:
381     break;
382   case Stmt::CompoundStmtClass:
383     EmitCompoundStmt(cast<CompoundStmt>(*S));
384     break;
385   case Stmt::DeclStmtClass:
386     EmitDeclStmt(cast<DeclStmt>(*S));
387     break;
388   case Stmt::LabelStmtClass:
389     EmitLabelStmt(cast<LabelStmt>(*S));
390     break;
391   case Stmt::AttributedStmtClass:
392     EmitAttributedStmt(cast<AttributedStmt>(*S));
393     break;
394   case Stmt::GotoStmtClass:
395     EmitGotoStmt(cast<GotoStmt>(*S));
396     break;
397   case Stmt::BreakStmtClass:
398     EmitBreakStmt(cast<BreakStmt>(*S));
399     break;
400   case Stmt::ContinueStmtClass:
401     EmitContinueStmt(cast<ContinueStmt>(*S));
402     break;
403   case Stmt::DefaultStmtClass:
404     EmitDefaultStmt(cast<DefaultStmt>(*S), Attrs);
405     break;
406   case Stmt::CaseStmtClass:
407     EmitCaseStmt(cast<CaseStmt>(*S), Attrs);
408     break;
409   case Stmt::SEHLeaveStmtClass:
410     EmitSEHLeaveStmt(cast<SEHLeaveStmt>(*S));
411     break;
412   }
413   return true;
414 }
415 
416 /// EmitCompoundStmt - Emit a compound statement {..} node.  If GetLast is true,
417 /// this captures the expression result of the last sub-statement and returns it
418 /// (for use by the statement expression extension).
419 Address CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast,
420                                           AggValueSlot AggSlot) {
421   PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),S.getLBracLoc(),
422                              "LLVM IR generation of compound statement ('{}')");
423 
424   // Keep track of the current cleanup stack depth, including debug scopes.
425   LexicalScope Scope(*this, S.getSourceRange());
426 
427   return EmitCompoundStmtWithoutScope(S, GetLast, AggSlot);
428 }
429 
430 Address
431 CodeGenFunction::EmitCompoundStmtWithoutScope(const CompoundStmt &S,
432                                               bool GetLast,
433                                               AggValueSlot AggSlot) {
434 
435   const Stmt *ExprResult = S.getStmtExprResult();
436   assert((!GetLast || (GetLast && ExprResult)) &&
437          "If GetLast is true then the CompoundStmt must have a StmtExprResult");
438 
439   Address RetAlloca = Address::invalid();
440 
441   for (auto *CurStmt : S.body()) {
442     if (GetLast && ExprResult == CurStmt) {
443       // We have to special case labels here.  They are statements, but when put
444       // at the end of a statement expression, they yield the value of their
445       // subexpression.  Handle this by walking through all labels we encounter,
446       // emitting them before we evaluate the subexpr.
447       // Similar issues arise for attributed statements.
448       while (!isa<Expr>(ExprResult)) {
449         if (const auto *LS = dyn_cast<LabelStmt>(ExprResult)) {
450           EmitLabel(LS->getDecl());
451           ExprResult = LS->getSubStmt();
452         } else if (const auto *AS = dyn_cast<AttributedStmt>(ExprResult)) {
453           // FIXME: Update this if we ever have attributes that affect the
454           // semantics of an expression.
455           ExprResult = AS->getSubStmt();
456         } else {
457           llvm_unreachable("unknown value statement");
458         }
459       }
460 
461       EnsureInsertPoint();
462 
463       const Expr *E = cast<Expr>(ExprResult);
464       QualType ExprTy = E->getType();
465       if (hasAggregateEvaluationKind(ExprTy)) {
466         EmitAggExpr(E, AggSlot);
467       } else {
468         // We can't return an RValue here because there might be cleanups at
469         // the end of the StmtExpr.  Because of that, we have to emit the result
470         // here into a temporary alloca.
471         RetAlloca = CreateMemTemp(ExprTy);
472         EmitAnyExprToMem(E, RetAlloca, Qualifiers(),
473                          /*IsInit*/ false);
474       }
475     } else {
476       EmitStmt(CurStmt);
477     }
478   }
479 
480   return RetAlloca;
481 }
482 
483 void CodeGenFunction::SimplifyForwardingBlocks(llvm::BasicBlock *BB) {
484   llvm::BranchInst *BI = dyn_cast<llvm::BranchInst>(BB->getTerminator());
485 
486   // If there is a cleanup stack, then we it isn't worth trying to
487   // simplify this block (we would need to remove it from the scope map
488   // and cleanup entry).
489   if (!EHStack.empty())
490     return;
491 
492   // Can only simplify direct branches.
493   if (!BI || !BI->isUnconditional())
494     return;
495 
496   // Can only simplify empty blocks.
497   if (BI->getIterator() != BB->begin())
498     return;
499 
500   BB->replaceAllUsesWith(BI->getSuccessor(0));
501   BI->eraseFromParent();
502   BB->eraseFromParent();
503 }
504 
505 void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) {
506   llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
507 
508   // Fall out of the current block (if necessary).
509   EmitBranch(BB);
510 
511   if (IsFinished && BB->use_empty()) {
512     delete BB;
513     return;
514   }
515 
516   // Place the block after the current block, if possible, or else at
517   // the end of the function.
518   if (CurBB && CurBB->getParent())
519     CurFn->getBasicBlockList().insertAfter(CurBB->getIterator(), BB);
520   else
521     CurFn->getBasicBlockList().push_back(BB);
522   Builder.SetInsertPoint(BB);
523 }
524 
525 void CodeGenFunction::EmitBranch(llvm::BasicBlock *Target) {
526   // Emit a branch from the current block to the target one if this
527   // was a real block.  If this was just a fall-through block after a
528   // terminator, don't emit it.
529   llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
530 
531   if (!CurBB || CurBB->getTerminator()) {
532     // If there is no insert point or the previous block is already
533     // terminated, don't touch it.
534   } else {
535     // Otherwise, create a fall-through branch.
536     Builder.CreateBr(Target);
537   }
538 
539   Builder.ClearInsertionPoint();
540 }
541 
542 void CodeGenFunction::EmitBlockAfterUses(llvm::BasicBlock *block) {
543   bool inserted = false;
544   for (llvm::User *u : block->users()) {
545     if (llvm::Instruction *insn = dyn_cast<llvm::Instruction>(u)) {
546       CurFn->getBasicBlockList().insertAfter(insn->getParent()->getIterator(),
547                                              block);
548       inserted = true;
549       break;
550     }
551   }
552 
553   if (!inserted)
554     CurFn->getBasicBlockList().push_back(block);
555 
556   Builder.SetInsertPoint(block);
557 }
558 
559 CodeGenFunction::JumpDest
560 CodeGenFunction::getJumpDestForLabel(const LabelDecl *D) {
561   JumpDest &Dest = LabelMap[D];
562   if (Dest.isValid()) return Dest;
563 
564   // Create, but don't insert, the new block.
565   Dest = JumpDest(createBasicBlock(D->getName()),
566                   EHScopeStack::stable_iterator::invalid(),
567                   NextCleanupDestIndex++);
568   return Dest;
569 }
570 
571 void CodeGenFunction::EmitLabel(const LabelDecl *D) {
572   // Add this label to the current lexical scope if we're within any
573   // normal cleanups.  Jumps "in" to this label --- when permitted by
574   // the language --- may need to be routed around such cleanups.
575   if (EHStack.hasNormalCleanups() && CurLexicalScope)
576     CurLexicalScope->addLabel(D);
577 
578   JumpDest &Dest = LabelMap[D];
579 
580   // If we didn't need a forward reference to this label, just go
581   // ahead and create a destination at the current scope.
582   if (!Dest.isValid()) {
583     Dest = getJumpDestInCurrentScope(D->getName());
584 
585   // Otherwise, we need to give this label a target depth and remove
586   // it from the branch-fixups list.
587   } else {
588     assert(!Dest.getScopeDepth().isValid() && "already emitted label!");
589     Dest.setScopeDepth(EHStack.stable_begin());
590     ResolveBranchFixups(Dest.getBlock());
591   }
592 
593   EmitBlock(Dest.getBlock());
594 
595   // Emit debug info for labels.
596   if (CGDebugInfo *DI = getDebugInfo()) {
597     if (CGM.getCodeGenOpts().hasReducedDebugInfo()) {
598       DI->setLocation(D->getLocation());
599       DI->EmitLabel(D, Builder);
600     }
601   }
602 
603   incrementProfileCounter(D->getStmt());
604 }
605 
606 /// Change the cleanup scope of the labels in this lexical scope to
607 /// match the scope of the enclosing context.
608 void CodeGenFunction::LexicalScope::rescopeLabels() {
609   assert(!Labels.empty());
610   EHScopeStack::stable_iterator innermostScope
611     = CGF.EHStack.getInnermostNormalCleanup();
612 
613   // Change the scope depth of all the labels.
614   for (SmallVectorImpl<const LabelDecl*>::const_iterator
615          i = Labels.begin(), e = Labels.end(); i != e; ++i) {
616     assert(CGF.LabelMap.count(*i));
617     JumpDest &dest = CGF.LabelMap.find(*i)->second;
618     assert(dest.getScopeDepth().isValid());
619     assert(innermostScope.encloses(dest.getScopeDepth()));
620     dest.setScopeDepth(innermostScope);
621   }
622 
623   // Reparent the labels if the new scope also has cleanups.
624   if (innermostScope != EHScopeStack::stable_end() && ParentScope) {
625     ParentScope->Labels.append(Labels.begin(), Labels.end());
626   }
627 }
628 
629 
630 void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) {
631   EmitLabel(S.getDecl());
632   EmitStmt(S.getSubStmt());
633 }
634 
635 void CodeGenFunction::EmitAttributedStmt(const AttributedStmt &S) {
636   bool nomerge = false;
637   for (const auto *A : S.getAttrs())
638     if (A->getKind() == attr::NoMerge) {
639       nomerge = true;
640       break;
641     }
642   SaveAndRestore<bool> save_nomerge(InNoMergeAttributedStmt, nomerge);
643   EmitStmt(S.getSubStmt(), S.getAttrs());
644 }
645 
646 void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) {
647   // If this code is reachable then emit a stop point (if generating
648   // debug info). We have to do this ourselves because we are on the
649   // "simple" statement path.
650   if (HaveInsertPoint())
651     EmitStopPoint(&S);
652 
653   EmitBranchThroughCleanup(getJumpDestForLabel(S.getLabel()));
654 }
655 
656 
657 void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) {
658   if (const LabelDecl *Target = S.getConstantTarget()) {
659     EmitBranchThroughCleanup(getJumpDestForLabel(Target));
660     return;
661   }
662 
663   // Ensure that we have an i8* for our PHI node.
664   llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()),
665                                          Int8PtrTy, "addr");
666   llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
667 
668   // Get the basic block for the indirect goto.
669   llvm::BasicBlock *IndGotoBB = GetIndirectGotoBlock();
670 
671   // The first instruction in the block has to be the PHI for the switch dest,
672   // add an entry for this branch.
673   cast<llvm::PHINode>(IndGotoBB->begin())->addIncoming(V, CurBB);
674 
675   EmitBranch(IndGotoBB);
676 }
677 
678 void CodeGenFunction::EmitIfStmt(const IfStmt &S) {
679   // C99 6.8.4.1: The first substatement is executed if the expression compares
680   // unequal to 0.  The condition must be a scalar type.
681   LexicalScope ConditionScope(*this, S.getCond()->getSourceRange());
682 
683   if (S.getInit())
684     EmitStmt(S.getInit());
685 
686   if (S.getConditionVariable())
687     EmitDecl(*S.getConditionVariable());
688 
689   // If the condition constant folds and can be elided, try to avoid emitting
690   // the condition and the dead arm of the if/else.
691   bool CondConstant;
692   if (ConstantFoldsToSimpleInteger(S.getCond(), CondConstant,
693                                    S.isConstexpr())) {
694     // Figure out which block (then or else) is executed.
695     const Stmt *Executed = S.getThen();
696     const Stmt *Skipped  = S.getElse();
697     if (!CondConstant)  // Condition false?
698       std::swap(Executed, Skipped);
699 
700     // If the skipped block has no labels in it, just emit the executed block.
701     // This avoids emitting dead code and simplifies the CFG substantially.
702     if (S.isConstexpr() || !ContainsLabel(Skipped)) {
703       if (CondConstant)
704         incrementProfileCounter(&S);
705       if (Executed) {
706         RunCleanupsScope ExecutedScope(*this);
707         EmitStmt(Executed);
708       }
709       return;
710     }
711   }
712 
713   // Otherwise, the condition did not fold, or we couldn't elide it.  Just emit
714   // the conditional branch.
715   llvm::BasicBlock *ThenBlock = createBasicBlock("if.then");
716   llvm::BasicBlock *ContBlock = createBasicBlock("if.end");
717   llvm::BasicBlock *ElseBlock = ContBlock;
718   if (S.getElse())
719     ElseBlock = createBasicBlock("if.else");
720 
721   // Prefer the PGO based weights over the likelihood attribute.
722   // When the build isn't optimized the metadata isn't used, so don't generate
723   // it.
724   Stmt::Likelihood LH = Stmt::LH_None;
725   uint64_t Count = getProfileCount(S.getThen());
726   if (!Count && CGM.getCodeGenOpts().OptimizationLevel)
727     LH = Stmt::getLikelihood(S.getThen(), S.getElse());
728   EmitBranchOnBoolExpr(S.getCond(), ThenBlock, ElseBlock, Count, LH);
729 
730   // Emit the 'then' code.
731   EmitBlock(ThenBlock);
732   incrementProfileCounter(&S);
733   {
734     RunCleanupsScope ThenScope(*this);
735     EmitStmt(S.getThen());
736   }
737   EmitBranch(ContBlock);
738 
739   // Emit the 'else' code if present.
740   if (const Stmt *Else = S.getElse()) {
741     {
742       // There is no need to emit line number for an unconditional branch.
743       auto NL = ApplyDebugLocation::CreateEmpty(*this);
744       EmitBlock(ElseBlock);
745     }
746     {
747       RunCleanupsScope ElseScope(*this);
748       EmitStmt(Else);
749     }
750     {
751       // There is no need to emit line number for an unconditional branch.
752       auto NL = ApplyDebugLocation::CreateEmpty(*this);
753       EmitBranch(ContBlock);
754     }
755   }
756 
757   // Emit the continuation block for code after the if.
758   EmitBlock(ContBlock, true);
759 }
760 
761 void CodeGenFunction::EmitWhileStmt(const WhileStmt &S,
762                                     ArrayRef<const Attr *> WhileAttrs) {
763   // Emit the header for the loop, which will also become
764   // the continue target.
765   JumpDest LoopHeader = getJumpDestInCurrentScope("while.cond");
766   EmitBlock(LoopHeader.getBlock());
767 
768   // Create an exit block for when the condition fails, which will
769   // also become the break target.
770   JumpDest LoopExit = getJumpDestInCurrentScope("while.end");
771 
772   // Store the blocks to use for break and continue.
773   BreakContinueStack.push_back(BreakContinue(LoopExit, LoopHeader));
774 
775   // C++ [stmt.while]p2:
776   //   When the condition of a while statement is a declaration, the
777   //   scope of the variable that is declared extends from its point
778   //   of declaration (3.3.2) to the end of the while statement.
779   //   [...]
780   //   The object created in a condition is destroyed and created
781   //   with each iteration of the loop.
782   RunCleanupsScope ConditionScope(*this);
783 
784   if (S.getConditionVariable())
785     EmitDecl(*S.getConditionVariable());
786 
787   // Evaluate the conditional in the while header.  C99 6.8.5.1: The
788   // evaluation of the controlling expression takes place before each
789   // execution of the loop body.
790   llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
791 
792   // while(1) is common, avoid extra exit blocks.  Be sure
793   // to correctly handle break/continue though.
794   bool EmitBoolCondBranch = true;
795   bool LoopMustProgress = false;
796   if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) {
797     if (C->isOne()) {
798       EmitBoolCondBranch = false;
799       FnIsMustProgress = false;
800     }
801   } else if (LanguageRequiresProgress())
802     LoopMustProgress = true;
803 
804   const SourceRange &R = S.getSourceRange();
805   LoopStack.push(LoopHeader.getBlock(), CGM.getContext(), CGM.getCodeGenOpts(),
806                  WhileAttrs, SourceLocToDebugLoc(R.getBegin()),
807                  SourceLocToDebugLoc(R.getEnd()), LoopMustProgress);
808 
809   // As long as the condition is true, go to the loop body.
810   llvm::BasicBlock *LoopBody = createBasicBlock("while.body");
811   if (EmitBoolCondBranch) {
812     llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
813     if (ConditionScope.requiresCleanups())
814       ExitBlock = createBasicBlock("while.exit");
815     llvm::MDNode *Weights = createProfileOrBranchWeightsForLoop(
816         S.getCond(), getProfileCount(S.getBody()), S.getBody());
817     Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock, Weights);
818 
819     if (ExitBlock != LoopExit.getBlock()) {
820       EmitBlock(ExitBlock);
821       EmitBranchThroughCleanup(LoopExit);
822     }
823   } else if (const Attr *A = Stmt::getLikelihoodAttr(S.getBody())) {
824     CGM.getDiags().Report(A->getLocation(),
825                           diag::warn_attribute_has_no_effect_on_infinite_loop)
826         << A << A->getRange();
827     CGM.getDiags().Report(
828         S.getWhileLoc(),
829         diag::note_attribute_has_no_effect_on_infinite_loop_here)
830         << SourceRange(S.getWhileLoc(), S.getRParenLoc());
831   }
832 
833   // Emit the loop body.  We have to emit this in a cleanup scope
834   // because it might be a singleton DeclStmt.
835   {
836     RunCleanupsScope BodyScope(*this);
837     EmitBlock(LoopBody);
838     incrementProfileCounter(&S);
839     EmitStmt(S.getBody());
840   }
841 
842   BreakContinueStack.pop_back();
843 
844   // Immediately force cleanup.
845   ConditionScope.ForceCleanup();
846 
847   EmitStopPoint(&S);
848   // Branch to the loop header again.
849   EmitBranch(LoopHeader.getBlock());
850 
851   LoopStack.pop();
852 
853   // Emit the exit block.
854   EmitBlock(LoopExit.getBlock(), true);
855 
856   // The LoopHeader typically is just a branch if we skipped emitting
857   // a branch, try to erase it.
858   if (!EmitBoolCondBranch)
859     SimplifyForwardingBlocks(LoopHeader.getBlock());
860 }
861 
862 void CodeGenFunction::EmitDoStmt(const DoStmt &S,
863                                  ArrayRef<const Attr *> DoAttrs) {
864   JumpDest LoopExit = getJumpDestInCurrentScope("do.end");
865   JumpDest LoopCond = getJumpDestInCurrentScope("do.cond");
866 
867   uint64_t ParentCount = getCurrentProfileCount();
868 
869   // Store the blocks to use for break and continue.
870   BreakContinueStack.push_back(BreakContinue(LoopExit, LoopCond));
871 
872   // Emit the body of the loop.
873   llvm::BasicBlock *LoopBody = createBasicBlock("do.body");
874 
875   EmitBlockWithFallThrough(LoopBody, &S);
876   {
877     RunCleanupsScope BodyScope(*this);
878     EmitStmt(S.getBody());
879   }
880 
881   EmitBlock(LoopCond.getBlock());
882 
883   // C99 6.8.5.2: "The evaluation of the controlling expression takes place
884   // after each execution of the loop body."
885 
886   // Evaluate the conditional in the while header.
887   // C99 6.8.5p2/p4: The first substatement is executed if the expression
888   // compares unequal to 0.  The condition must be a scalar type.
889   llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
890 
891   BreakContinueStack.pop_back();
892 
893   // "do {} while (0)" is common in macros, avoid extra blocks.  Be sure
894   // to correctly handle break/continue though.
895   bool EmitBoolCondBranch = true;
896   bool LoopMustProgress = false;
897   if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal)) {
898     if (C->isZero())
899       EmitBoolCondBranch = false;
900     else if (C->isOne())
901       FnIsMustProgress = false;
902   } else if (LanguageRequiresProgress())
903     LoopMustProgress = true;
904 
905   const SourceRange &R = S.getSourceRange();
906   LoopStack.push(LoopBody, CGM.getContext(), CGM.getCodeGenOpts(), DoAttrs,
907                  SourceLocToDebugLoc(R.getBegin()),
908                  SourceLocToDebugLoc(R.getEnd()), LoopMustProgress);
909 
910   // As long as the condition is true, iterate the loop.
911   if (EmitBoolCondBranch) {
912     uint64_t BackedgeCount = getProfileCount(S.getBody()) - ParentCount;
913     Builder.CreateCondBr(
914         BoolCondVal, LoopBody, LoopExit.getBlock(),
915         createProfileWeightsForLoop(S.getCond(), BackedgeCount));
916   }
917 
918   LoopStack.pop();
919 
920   // Emit the exit block.
921   EmitBlock(LoopExit.getBlock());
922 
923   // The DoCond block typically is just a branch if we skipped
924   // emitting a branch, try to erase it.
925   if (!EmitBoolCondBranch)
926     SimplifyForwardingBlocks(LoopCond.getBlock());
927 }
928 
929 void CodeGenFunction::EmitForStmt(const ForStmt &S,
930                                   ArrayRef<const Attr *> ForAttrs) {
931   JumpDest LoopExit = getJumpDestInCurrentScope("for.end");
932 
933   LexicalScope ForScope(*this, S.getSourceRange());
934 
935   // Evaluate the first part before the loop.
936   if (S.getInit())
937     EmitStmt(S.getInit());
938 
939   // Start the loop with a block that tests the condition.
940   // If there's an increment, the continue scope will be overwritten
941   // later.
942   JumpDest Continue = getJumpDestInCurrentScope("for.cond");
943   llvm::BasicBlock *CondBlock = Continue.getBlock();
944   EmitBlock(CondBlock);
945 
946   bool LoopMustProgress = false;
947   Expr::EvalResult Result;
948   if (LanguageRequiresProgress()) {
949     if (!S.getCond()) {
950       FnIsMustProgress = false;
951     } else if (!S.getCond()->EvaluateAsInt(Result, getContext())) {
952       LoopMustProgress = true;
953     }
954   }
955 
956   const SourceRange &R = S.getSourceRange();
957   LoopStack.push(CondBlock, CGM.getContext(), CGM.getCodeGenOpts(), ForAttrs,
958                  SourceLocToDebugLoc(R.getBegin()),
959                  SourceLocToDebugLoc(R.getEnd()), LoopMustProgress);
960 
961   // If the for loop doesn't have an increment we can just use the
962   // condition as the continue block.  Otherwise we'll need to create
963   // a block for it (in the current scope, i.e. in the scope of the
964   // condition), and that we will become our continue block.
965   if (S.getInc())
966     Continue = getJumpDestInCurrentScope("for.inc");
967 
968   // Store the blocks to use for break and continue.
969   BreakContinueStack.push_back(BreakContinue(LoopExit, Continue));
970 
971   // Create a cleanup scope for the condition variable cleanups.
972   LexicalScope ConditionScope(*this, S.getSourceRange());
973 
974   if (S.getCond()) {
975     // If the for statement has a condition scope, emit the local variable
976     // declaration.
977     if (S.getConditionVariable()) {
978       EmitDecl(*S.getConditionVariable());
979     }
980 
981     llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
982     // If there are any cleanups between here and the loop-exit scope,
983     // create a block to stage a loop exit along.
984     if (ForScope.requiresCleanups())
985       ExitBlock = createBasicBlock("for.cond.cleanup");
986 
987     // As long as the condition is true, iterate the loop.
988     llvm::BasicBlock *ForBody = createBasicBlock("for.body");
989 
990     // C99 6.8.5p2/p4: The first substatement is executed if the expression
991     // compares unequal to 0.  The condition must be a scalar type.
992     llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
993     llvm::MDNode *Weights = createProfileOrBranchWeightsForLoop(
994         S.getCond(), getProfileCount(S.getBody()), S.getBody());
995 
996     if (llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal))
997       if (C->isOne())
998         FnIsMustProgress = false;
999 
1000     Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock, Weights);
1001 
1002     if (ExitBlock != LoopExit.getBlock()) {
1003       EmitBlock(ExitBlock);
1004       EmitBranchThroughCleanup(LoopExit);
1005     }
1006 
1007     EmitBlock(ForBody);
1008   } else {
1009     // Treat it as a non-zero constant.  Don't even create a new block for the
1010     // body, just fall into it.
1011   }
1012   incrementProfileCounter(&S);
1013 
1014   {
1015     // Create a separate cleanup scope for the body, in case it is not
1016     // a compound statement.
1017     RunCleanupsScope BodyScope(*this);
1018     EmitStmt(S.getBody());
1019   }
1020 
1021   // If there is an increment, emit it next.
1022   if (S.getInc()) {
1023     EmitBlock(Continue.getBlock());
1024     EmitStmt(S.getInc());
1025   }
1026 
1027   BreakContinueStack.pop_back();
1028 
1029   ConditionScope.ForceCleanup();
1030 
1031   EmitStopPoint(&S);
1032   EmitBranch(CondBlock);
1033 
1034   ForScope.ForceCleanup();
1035 
1036   LoopStack.pop();
1037 
1038   // Emit the fall-through block.
1039   EmitBlock(LoopExit.getBlock(), true);
1040 }
1041 
1042 void
1043 CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S,
1044                                      ArrayRef<const Attr *> ForAttrs) {
1045   JumpDest LoopExit = getJumpDestInCurrentScope("for.end");
1046 
1047   LexicalScope ForScope(*this, S.getSourceRange());
1048 
1049   // Evaluate the first pieces before the loop.
1050   if (S.getInit())
1051     EmitStmt(S.getInit());
1052   EmitStmt(S.getRangeStmt());
1053   EmitStmt(S.getBeginStmt());
1054   EmitStmt(S.getEndStmt());
1055 
1056   // Start the loop with a block that tests the condition.
1057   // If there's an increment, the continue scope will be overwritten
1058   // later.
1059   llvm::BasicBlock *CondBlock = createBasicBlock("for.cond");
1060   EmitBlock(CondBlock);
1061 
1062   const SourceRange &R = S.getSourceRange();
1063   LoopStack.push(CondBlock, CGM.getContext(), CGM.getCodeGenOpts(), ForAttrs,
1064                  SourceLocToDebugLoc(R.getBegin()),
1065                  SourceLocToDebugLoc(R.getEnd()));
1066 
1067   // If there are any cleanups between here and the loop-exit scope,
1068   // create a block to stage a loop exit along.
1069   llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
1070   if (ForScope.requiresCleanups())
1071     ExitBlock = createBasicBlock("for.cond.cleanup");
1072 
1073   // The loop body, consisting of the specified body and the loop variable.
1074   llvm::BasicBlock *ForBody = createBasicBlock("for.body");
1075 
1076   // The body is executed if the expression, contextually converted
1077   // to bool, is true.
1078   llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
1079   llvm::MDNode *Weights = createProfileOrBranchWeightsForLoop(
1080       S.getCond(), getProfileCount(S.getBody()), S.getBody());
1081   Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock, Weights);
1082 
1083   if (ExitBlock != LoopExit.getBlock()) {
1084     EmitBlock(ExitBlock);
1085     EmitBranchThroughCleanup(LoopExit);
1086   }
1087 
1088   EmitBlock(ForBody);
1089   incrementProfileCounter(&S);
1090 
1091   // Create a block for the increment. In case of a 'continue', we jump there.
1092   JumpDest Continue = getJumpDestInCurrentScope("for.inc");
1093 
1094   // Store the blocks to use for break and continue.
1095   BreakContinueStack.push_back(BreakContinue(LoopExit, Continue));
1096 
1097   {
1098     // Create a separate cleanup scope for the loop variable and body.
1099     LexicalScope BodyScope(*this, S.getSourceRange());
1100     EmitStmt(S.getLoopVarStmt());
1101     EmitStmt(S.getBody());
1102   }
1103 
1104   EmitStopPoint(&S);
1105   // If there is an increment, emit it next.
1106   EmitBlock(Continue.getBlock());
1107   EmitStmt(S.getInc());
1108 
1109   BreakContinueStack.pop_back();
1110 
1111   EmitBranch(CondBlock);
1112 
1113   ForScope.ForceCleanup();
1114 
1115   LoopStack.pop();
1116 
1117   // Emit the fall-through block.
1118   EmitBlock(LoopExit.getBlock(), true);
1119 }
1120 
1121 void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) {
1122   if (RV.isScalar()) {
1123     Builder.CreateStore(RV.getScalarVal(), ReturnValue);
1124   } else if (RV.isAggregate()) {
1125     LValue Dest = MakeAddrLValue(ReturnValue, Ty);
1126     LValue Src = MakeAddrLValue(RV.getAggregateAddress(), Ty);
1127     EmitAggregateCopy(Dest, Src, Ty, getOverlapForReturnValue());
1128   } else {
1129     EmitStoreOfComplex(RV.getComplexVal(), MakeAddrLValue(ReturnValue, Ty),
1130                        /*init*/ true);
1131   }
1132   EmitBranchThroughCleanup(ReturnBlock);
1133 }
1134 
1135 namespace {
1136 // RAII struct used to save and restore a return statment's result expression.
1137 struct SaveRetExprRAII {
1138   SaveRetExprRAII(const Expr *RetExpr, CodeGenFunction &CGF)
1139       : OldRetExpr(CGF.RetExpr), CGF(CGF) {
1140     CGF.RetExpr = RetExpr;
1141   }
1142   ~SaveRetExprRAII() { CGF.RetExpr = OldRetExpr; }
1143   const Expr *OldRetExpr;
1144   CodeGenFunction &CGF;
1145 };
1146 } // namespace
1147 
1148 /// EmitReturnStmt - Note that due to GCC extensions, this can have an operand
1149 /// if the function returns void, or may be missing one if the function returns
1150 /// non-void.  Fun stuff :).
1151 void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) {
1152   if (requiresReturnValueCheck()) {
1153     llvm::Constant *SLoc = EmitCheckSourceLocation(S.getBeginLoc());
1154     auto *SLocPtr =
1155         new llvm::GlobalVariable(CGM.getModule(), SLoc->getType(), false,
1156                                  llvm::GlobalVariable::PrivateLinkage, SLoc);
1157     SLocPtr->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1158     CGM.getSanitizerMetadata()->disableSanitizerForGlobal(SLocPtr);
1159     assert(ReturnLocation.isValid() && "No valid return location");
1160     Builder.CreateStore(Builder.CreateBitCast(SLocPtr, Int8PtrTy),
1161                         ReturnLocation);
1162   }
1163 
1164   // Returning from an outlined SEH helper is UB, and we already warn on it.
1165   if (IsOutlinedSEHHelper) {
1166     Builder.CreateUnreachable();
1167     Builder.ClearInsertionPoint();
1168   }
1169 
1170   // Emit the result value, even if unused, to evaluate the side effects.
1171   const Expr *RV = S.getRetValue();
1172 
1173   // Record the result expression of the return statement. The recorded
1174   // expression is used to determine whether a block capture's lifetime should
1175   // end at the end of the full expression as opposed to the end of the scope
1176   // enclosing the block expression.
1177   //
1178   // This permits a small, easily-implemented exception to our over-conservative
1179   // rules about not jumping to statements following block literals with
1180   // non-trivial cleanups.
1181   SaveRetExprRAII SaveRetExpr(RV, *this);
1182 
1183   RunCleanupsScope cleanupScope(*this);
1184   if (const auto *EWC = dyn_cast_or_null<ExprWithCleanups>(RV))
1185     RV = EWC->getSubExpr();
1186   // FIXME: Clean this up by using an LValue for ReturnTemp,
1187   // EmitStoreThroughLValue, and EmitAnyExpr.
1188   // Check if the NRVO candidate was not globalized in OpenMP mode.
1189   if (getLangOpts().ElideConstructors && S.getNRVOCandidate() &&
1190       S.getNRVOCandidate()->isNRVOVariable() &&
1191       (!getLangOpts().OpenMP ||
1192        !CGM.getOpenMPRuntime()
1193             .getAddressOfLocalVariable(*this, S.getNRVOCandidate())
1194             .isValid())) {
1195     // Apply the named return value optimization for this return statement,
1196     // which means doing nothing: the appropriate result has already been
1197     // constructed into the NRVO variable.
1198 
1199     // If there is an NRVO flag for this variable, set it to 1 into indicate
1200     // that the cleanup code should not destroy the variable.
1201     if (llvm::Value *NRVOFlag = NRVOFlags[S.getNRVOCandidate()])
1202       Builder.CreateFlagStore(Builder.getTrue(), NRVOFlag);
1203   } else if (!ReturnValue.isValid() || (RV && RV->getType()->isVoidType())) {
1204     // Make sure not to return anything, but evaluate the expression
1205     // for side effects.
1206     if (RV)
1207       EmitAnyExpr(RV);
1208   } else if (!RV) {
1209     // Do nothing (return value is left uninitialized)
1210   } else if (FnRetTy->isReferenceType()) {
1211     // If this function returns a reference, take the address of the expression
1212     // rather than the value.
1213     RValue Result = EmitReferenceBindingToExpr(RV);
1214     Builder.CreateStore(Result.getScalarVal(), ReturnValue);
1215   } else {
1216     switch (getEvaluationKind(RV->getType())) {
1217     case TEK_Scalar:
1218       Builder.CreateStore(EmitScalarExpr(RV), ReturnValue);
1219       break;
1220     case TEK_Complex:
1221       EmitComplexExprIntoLValue(RV, MakeAddrLValue(ReturnValue, RV->getType()),
1222                                 /*isInit*/ true);
1223       break;
1224     case TEK_Aggregate:
1225       EmitAggExpr(RV, AggValueSlot::forAddr(
1226                           ReturnValue, Qualifiers(),
1227                           AggValueSlot::IsDestructed,
1228                           AggValueSlot::DoesNotNeedGCBarriers,
1229                           AggValueSlot::IsNotAliased,
1230                           getOverlapForReturnValue()));
1231       break;
1232     }
1233   }
1234 
1235   ++NumReturnExprs;
1236   if (!RV || RV->isEvaluatable(getContext()))
1237     ++NumSimpleReturnExprs;
1238 
1239   cleanupScope.ForceCleanup();
1240   EmitBranchThroughCleanup(ReturnBlock);
1241 }
1242 
1243 void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) {
1244   // As long as debug info is modeled with instructions, we have to ensure we
1245   // have a place to insert here and write the stop point here.
1246   if (HaveInsertPoint())
1247     EmitStopPoint(&S);
1248 
1249   for (const auto *I : S.decls())
1250     EmitDecl(*I);
1251 }
1252 
1253 void CodeGenFunction::EmitBreakStmt(const BreakStmt &S) {
1254   assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!");
1255 
1256   // If this code is reachable then emit a stop point (if generating
1257   // debug info). We have to do this ourselves because we are on the
1258   // "simple" statement path.
1259   if (HaveInsertPoint())
1260     EmitStopPoint(&S);
1261 
1262   EmitBranchThroughCleanup(BreakContinueStack.back().BreakBlock);
1263 }
1264 
1265 void CodeGenFunction::EmitContinueStmt(const ContinueStmt &S) {
1266   assert(!BreakContinueStack.empty() && "continue stmt not in a loop!");
1267 
1268   // If this code is reachable then emit a stop point (if generating
1269   // debug info). We have to do this ourselves because we are on the
1270   // "simple" statement path.
1271   if (HaveInsertPoint())
1272     EmitStopPoint(&S);
1273 
1274   EmitBranchThroughCleanup(BreakContinueStack.back().ContinueBlock);
1275 }
1276 
1277 /// EmitCaseStmtRange - If case statement range is not too big then
1278 /// add multiple cases to switch instruction, one for each value within
1279 /// the range. If range is too big then emit "if" condition check.
1280 void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S,
1281                                         ArrayRef<const Attr *> Attrs) {
1282   assert(S.getRHS() && "Expected RHS value in CaseStmt");
1283 
1284   llvm::APSInt LHS = S.getLHS()->EvaluateKnownConstInt(getContext());
1285   llvm::APSInt RHS = S.getRHS()->EvaluateKnownConstInt(getContext());
1286 
1287   // Emit the code for this case. We do this first to make sure it is
1288   // properly chained from our predecessor before generating the
1289   // switch machinery to enter this block.
1290   llvm::BasicBlock *CaseDest = createBasicBlock("sw.bb");
1291   EmitBlockWithFallThrough(CaseDest, &S);
1292   EmitStmt(S.getSubStmt());
1293 
1294   // If range is empty, do nothing.
1295   if (LHS.isSigned() ? RHS.slt(LHS) : RHS.ult(LHS))
1296     return;
1297 
1298   Stmt::Likelihood LH = Stmt::getLikelihood(Attrs);
1299   llvm::APInt Range = RHS - LHS;
1300   // FIXME: parameters such as this should not be hardcoded.
1301   if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) {
1302     // Range is small enough to add multiple switch instruction cases.
1303     uint64_t Total = getProfileCount(&S);
1304     unsigned NCases = Range.getZExtValue() + 1;
1305     // We only have one region counter for the entire set of cases here, so we
1306     // need to divide the weights evenly between the generated cases, ensuring
1307     // that the total weight is preserved. E.g., a weight of 5 over three cases
1308     // will be distributed as weights of 2, 2, and 1.
1309     uint64_t Weight = Total / NCases, Rem = Total % NCases;
1310     for (unsigned I = 0; I != NCases; ++I) {
1311       if (SwitchWeights)
1312         SwitchWeights->push_back(Weight + (Rem ? 1 : 0));
1313       else if (SwitchLikelihood)
1314         SwitchLikelihood->push_back(LH);
1315 
1316       if (Rem)
1317         Rem--;
1318       SwitchInsn->addCase(Builder.getInt(LHS), CaseDest);
1319       ++LHS;
1320     }
1321     return;
1322   }
1323 
1324   // The range is too big. Emit "if" condition into a new block,
1325   // making sure to save and restore the current insertion point.
1326   llvm::BasicBlock *RestoreBB = Builder.GetInsertBlock();
1327 
1328   // Push this test onto the chain of range checks (which terminates
1329   // in the default basic block). The switch's default will be changed
1330   // to the top of this chain after switch emission is complete.
1331   llvm::BasicBlock *FalseDest = CaseRangeBlock;
1332   CaseRangeBlock = createBasicBlock("sw.caserange");
1333 
1334   CurFn->getBasicBlockList().push_back(CaseRangeBlock);
1335   Builder.SetInsertPoint(CaseRangeBlock);
1336 
1337   // Emit range check.
1338   llvm::Value *Diff =
1339     Builder.CreateSub(SwitchInsn->getCondition(), Builder.getInt(LHS));
1340   llvm::Value *Cond =
1341     Builder.CreateICmpULE(Diff, Builder.getInt(Range), "inbounds");
1342 
1343   llvm::MDNode *Weights = nullptr;
1344   if (SwitchWeights) {
1345     uint64_t ThisCount = getProfileCount(&S);
1346     uint64_t DefaultCount = (*SwitchWeights)[0];
1347     Weights = createProfileWeights(ThisCount, DefaultCount);
1348 
1349     // Since we're chaining the switch default through each large case range, we
1350     // need to update the weight for the default, ie, the first case, to include
1351     // this case.
1352     (*SwitchWeights)[0] += ThisCount;
1353   } else if (SwitchLikelihood)
1354     Weights = createBranchWeights(LH);
1355 
1356   Builder.CreateCondBr(Cond, CaseDest, FalseDest, Weights);
1357 
1358   // Restore the appropriate insertion point.
1359   if (RestoreBB)
1360     Builder.SetInsertPoint(RestoreBB);
1361   else
1362     Builder.ClearInsertionPoint();
1363 }
1364 
1365 void CodeGenFunction::EmitCaseStmt(const CaseStmt &S,
1366                                    ArrayRef<const Attr *> Attrs) {
1367   // If there is no enclosing switch instance that we're aware of, then this
1368   // case statement and its block can be elided.  This situation only happens
1369   // when we've constant-folded the switch, are emitting the constant case,
1370   // and part of the constant case includes another case statement.  For
1371   // instance: switch (4) { case 4: do { case 5: } while (1); }
1372   if (!SwitchInsn) {
1373     EmitStmt(S.getSubStmt());
1374     return;
1375   }
1376 
1377   // Handle case ranges.
1378   if (S.getRHS()) {
1379     EmitCaseStmtRange(S, Attrs);
1380     return;
1381   }
1382 
1383   llvm::ConstantInt *CaseVal =
1384     Builder.getInt(S.getLHS()->EvaluateKnownConstInt(getContext()));
1385   if (SwitchLikelihood)
1386     SwitchLikelihood->push_back(Stmt::getLikelihood(Attrs));
1387 
1388   // If the body of the case is just a 'break', try to not emit an empty block.
1389   // If we're profiling or we're not optimizing, leave the block in for better
1390   // debug and coverage analysis.
1391   if (!CGM.getCodeGenOpts().hasProfileClangInstr() &&
1392       CGM.getCodeGenOpts().OptimizationLevel > 0 &&
1393       isa<BreakStmt>(S.getSubStmt())) {
1394     JumpDest Block = BreakContinueStack.back().BreakBlock;
1395 
1396     // Only do this optimization if there are no cleanups that need emitting.
1397     if (isObviouslyBranchWithoutCleanups(Block)) {
1398       if (SwitchWeights)
1399         SwitchWeights->push_back(getProfileCount(&S));
1400       SwitchInsn->addCase(CaseVal, Block.getBlock());
1401 
1402       // If there was a fallthrough into this case, make sure to redirect it to
1403       // the end of the switch as well.
1404       if (Builder.GetInsertBlock()) {
1405         Builder.CreateBr(Block.getBlock());
1406         Builder.ClearInsertionPoint();
1407       }
1408       return;
1409     }
1410   }
1411 
1412   llvm::BasicBlock *CaseDest = createBasicBlock("sw.bb");
1413   EmitBlockWithFallThrough(CaseDest, &S);
1414   if (SwitchWeights)
1415     SwitchWeights->push_back(getProfileCount(&S));
1416   SwitchInsn->addCase(CaseVal, CaseDest);
1417 
1418   // Recursively emitting the statement is acceptable, but is not wonderful for
1419   // code where we have many case statements nested together, i.e.:
1420   //  case 1:
1421   //    case 2:
1422   //      case 3: etc.
1423   // Handling this recursively will create a new block for each case statement
1424   // that falls through to the next case which is IR intensive.  It also causes
1425   // deep recursion which can run into stack depth limitations.  Handle
1426   // sequential non-range case statements specially.
1427   //
1428   // TODO When the next case has a likelihood attribute the code returns to the
1429   // recursive algorithm. Maybe improve this case if it becomes common practice
1430   // to use a lot of attributes.
1431   const CaseStmt *CurCase = &S;
1432   const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt());
1433 
1434   // Otherwise, iteratively add consecutive cases to this switch stmt.
1435   while (NextCase && NextCase->getRHS() == nullptr) {
1436     CurCase = NextCase;
1437     llvm::ConstantInt *CaseVal =
1438       Builder.getInt(CurCase->getLHS()->EvaluateKnownConstInt(getContext()));
1439 
1440     if (SwitchWeights)
1441       SwitchWeights->push_back(getProfileCount(NextCase));
1442     if (CGM.getCodeGenOpts().hasProfileClangInstr()) {
1443       CaseDest = createBasicBlock("sw.bb");
1444       EmitBlockWithFallThrough(CaseDest, CurCase);
1445     }
1446     // Since this loop is only executed when the CaseStmt has no attributes
1447     // use a hard-coded value.
1448     if (SwitchLikelihood)
1449       SwitchLikelihood->push_back(Stmt::LH_None);
1450 
1451     SwitchInsn->addCase(CaseVal, CaseDest);
1452     NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt());
1453   }
1454 
1455   // Normal default recursion for non-cases.
1456   EmitStmt(CurCase->getSubStmt());
1457 }
1458 
1459 void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S,
1460                                       ArrayRef<const Attr *> Attrs) {
1461   // If there is no enclosing switch instance that we're aware of, then this
1462   // default statement can be elided. This situation only happens when we've
1463   // constant-folded the switch.
1464   if (!SwitchInsn) {
1465     EmitStmt(S.getSubStmt());
1466     return;
1467   }
1468 
1469   llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest();
1470   assert(DefaultBlock->empty() &&
1471          "EmitDefaultStmt: Default block already defined?");
1472 
1473   if (SwitchLikelihood)
1474     SwitchLikelihood->front() = Stmt::getLikelihood(Attrs);
1475 
1476   EmitBlockWithFallThrough(DefaultBlock, &S);
1477 
1478   EmitStmt(S.getSubStmt());
1479 }
1480 
1481 /// CollectStatementsForCase - Given the body of a 'switch' statement and a
1482 /// constant value that is being switched on, see if we can dead code eliminate
1483 /// the body of the switch to a simple series of statements to emit.  Basically,
1484 /// on a switch (5) we want to find these statements:
1485 ///    case 5:
1486 ///      printf(...);    <--
1487 ///      ++i;            <--
1488 ///      break;
1489 ///
1490 /// and add them to the ResultStmts vector.  If it is unsafe to do this
1491 /// transformation (for example, one of the elided statements contains a label
1492 /// that might be jumped to), return CSFC_Failure.  If we handled it and 'S'
1493 /// should include statements after it (e.g. the printf() line is a substmt of
1494 /// the case) then return CSFC_FallThrough.  If we handled it and found a break
1495 /// statement, then return CSFC_Success.
1496 ///
1497 /// If Case is non-null, then we are looking for the specified case, checking
1498 /// that nothing we jump over contains labels.  If Case is null, then we found
1499 /// the case and are looking for the break.
1500 ///
1501 /// If the recursive walk actually finds our Case, then we set FoundCase to
1502 /// true.
1503 ///
1504 enum CSFC_Result { CSFC_Failure, CSFC_FallThrough, CSFC_Success };
1505 static CSFC_Result CollectStatementsForCase(const Stmt *S,
1506                                             const SwitchCase *Case,
1507                                             bool &FoundCase,
1508                               SmallVectorImpl<const Stmt*> &ResultStmts) {
1509   // If this is a null statement, just succeed.
1510   if (!S)
1511     return Case ? CSFC_Success : CSFC_FallThrough;
1512 
1513   // If this is the switchcase (case 4: or default) that we're looking for, then
1514   // we're in business.  Just add the substatement.
1515   if (const SwitchCase *SC = dyn_cast<SwitchCase>(S)) {
1516     if (S == Case) {
1517       FoundCase = true;
1518       return CollectStatementsForCase(SC->getSubStmt(), nullptr, FoundCase,
1519                                       ResultStmts);
1520     }
1521 
1522     // Otherwise, this is some other case or default statement, just ignore it.
1523     return CollectStatementsForCase(SC->getSubStmt(), Case, FoundCase,
1524                                     ResultStmts);
1525   }
1526 
1527   // If we are in the live part of the code and we found our break statement,
1528   // return a success!
1529   if (!Case && isa<BreakStmt>(S))
1530     return CSFC_Success;
1531 
1532   // If this is a switch statement, then it might contain the SwitchCase, the
1533   // break, or neither.
1534   if (const CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) {
1535     // Handle this as two cases: we might be looking for the SwitchCase (if so
1536     // the skipped statements must be skippable) or we might already have it.
1537     CompoundStmt::const_body_iterator I = CS->body_begin(), E = CS->body_end();
1538     bool StartedInLiveCode = FoundCase;
1539     unsigned StartSize = ResultStmts.size();
1540 
1541     // If we've not found the case yet, scan through looking for it.
1542     if (Case) {
1543       // Keep track of whether we see a skipped declaration.  The code could be
1544       // using the declaration even if it is skipped, so we can't optimize out
1545       // the decl if the kept statements might refer to it.
1546       bool HadSkippedDecl = false;
1547 
1548       // If we're looking for the case, just see if we can skip each of the
1549       // substatements.
1550       for (; Case && I != E; ++I) {
1551         HadSkippedDecl |= CodeGenFunction::mightAddDeclToScope(*I);
1552 
1553         switch (CollectStatementsForCase(*I, Case, FoundCase, ResultStmts)) {
1554         case CSFC_Failure: return CSFC_Failure;
1555         case CSFC_Success:
1556           // A successful result means that either 1) that the statement doesn't
1557           // have the case and is skippable, or 2) does contain the case value
1558           // and also contains the break to exit the switch.  In the later case,
1559           // we just verify the rest of the statements are elidable.
1560           if (FoundCase) {
1561             // If we found the case and skipped declarations, we can't do the
1562             // optimization.
1563             if (HadSkippedDecl)
1564               return CSFC_Failure;
1565 
1566             for (++I; I != E; ++I)
1567               if (CodeGenFunction::ContainsLabel(*I, true))
1568                 return CSFC_Failure;
1569             return CSFC_Success;
1570           }
1571           break;
1572         case CSFC_FallThrough:
1573           // If we have a fallthrough condition, then we must have found the
1574           // case started to include statements.  Consider the rest of the
1575           // statements in the compound statement as candidates for inclusion.
1576           assert(FoundCase && "Didn't find case but returned fallthrough?");
1577           // We recursively found Case, so we're not looking for it anymore.
1578           Case = nullptr;
1579 
1580           // If we found the case and skipped declarations, we can't do the
1581           // optimization.
1582           if (HadSkippedDecl)
1583             return CSFC_Failure;
1584           break;
1585         }
1586       }
1587 
1588       if (!FoundCase)
1589         return CSFC_Success;
1590 
1591       assert(!HadSkippedDecl && "fallthrough after skipping decl");
1592     }
1593 
1594     // If we have statements in our range, then we know that the statements are
1595     // live and need to be added to the set of statements we're tracking.
1596     bool AnyDecls = false;
1597     for (; I != E; ++I) {
1598       AnyDecls |= CodeGenFunction::mightAddDeclToScope(*I);
1599 
1600       switch (CollectStatementsForCase(*I, nullptr, FoundCase, ResultStmts)) {
1601       case CSFC_Failure: return CSFC_Failure;
1602       case CSFC_FallThrough:
1603         // A fallthrough result means that the statement was simple and just
1604         // included in ResultStmt, keep adding them afterwards.
1605         break;
1606       case CSFC_Success:
1607         // A successful result means that we found the break statement and
1608         // stopped statement inclusion.  We just ensure that any leftover stmts
1609         // are skippable and return success ourselves.
1610         for (++I; I != E; ++I)
1611           if (CodeGenFunction::ContainsLabel(*I, true))
1612             return CSFC_Failure;
1613         return CSFC_Success;
1614       }
1615     }
1616 
1617     // If we're about to fall out of a scope without hitting a 'break;', we
1618     // can't perform the optimization if there were any decls in that scope
1619     // (we'd lose their end-of-lifetime).
1620     if (AnyDecls) {
1621       // If the entire compound statement was live, there's one more thing we
1622       // can try before giving up: emit the whole thing as a single statement.
1623       // We can do that unless the statement contains a 'break;'.
1624       // FIXME: Such a break must be at the end of a construct within this one.
1625       // We could emit this by just ignoring the BreakStmts entirely.
1626       if (StartedInLiveCode && !CodeGenFunction::containsBreak(S)) {
1627         ResultStmts.resize(StartSize);
1628         ResultStmts.push_back(S);
1629       } else {
1630         return CSFC_Failure;
1631       }
1632     }
1633 
1634     return CSFC_FallThrough;
1635   }
1636 
1637   // Okay, this is some other statement that we don't handle explicitly, like a
1638   // for statement or increment etc.  If we are skipping over this statement,
1639   // just verify it doesn't have labels, which would make it invalid to elide.
1640   if (Case) {
1641     if (CodeGenFunction::ContainsLabel(S, true))
1642       return CSFC_Failure;
1643     return CSFC_Success;
1644   }
1645 
1646   // Otherwise, we want to include this statement.  Everything is cool with that
1647   // so long as it doesn't contain a break out of the switch we're in.
1648   if (CodeGenFunction::containsBreak(S)) return CSFC_Failure;
1649 
1650   // Otherwise, everything is great.  Include the statement and tell the caller
1651   // that we fall through and include the next statement as well.
1652   ResultStmts.push_back(S);
1653   return CSFC_FallThrough;
1654 }
1655 
1656 /// FindCaseStatementsForValue - Find the case statement being jumped to and
1657 /// then invoke CollectStatementsForCase to find the list of statements to emit
1658 /// for a switch on constant.  See the comment above CollectStatementsForCase
1659 /// for more details.
1660 static bool FindCaseStatementsForValue(const SwitchStmt &S,
1661                                        const llvm::APSInt &ConstantCondValue,
1662                                 SmallVectorImpl<const Stmt*> &ResultStmts,
1663                                        ASTContext &C,
1664                                        const SwitchCase *&ResultCase) {
1665   // First step, find the switch case that is being branched to.  We can do this
1666   // efficiently by scanning the SwitchCase list.
1667   const SwitchCase *Case = S.getSwitchCaseList();
1668   const DefaultStmt *DefaultCase = nullptr;
1669 
1670   for (; Case; Case = Case->getNextSwitchCase()) {
1671     // It's either a default or case.  Just remember the default statement in
1672     // case we're not jumping to any numbered cases.
1673     if (const DefaultStmt *DS = dyn_cast<DefaultStmt>(Case)) {
1674       DefaultCase = DS;
1675       continue;
1676     }
1677 
1678     // Check to see if this case is the one we're looking for.
1679     const CaseStmt *CS = cast<CaseStmt>(Case);
1680     // Don't handle case ranges yet.
1681     if (CS->getRHS()) return false;
1682 
1683     // If we found our case, remember it as 'case'.
1684     if (CS->getLHS()->EvaluateKnownConstInt(C) == ConstantCondValue)
1685       break;
1686   }
1687 
1688   // If we didn't find a matching case, we use a default if it exists, or we
1689   // elide the whole switch body!
1690   if (!Case) {
1691     // It is safe to elide the body of the switch if it doesn't contain labels
1692     // etc.  If it is safe, return successfully with an empty ResultStmts list.
1693     if (!DefaultCase)
1694       return !CodeGenFunction::ContainsLabel(&S);
1695     Case = DefaultCase;
1696   }
1697 
1698   // Ok, we know which case is being jumped to, try to collect all the
1699   // statements that follow it.  This can fail for a variety of reasons.  Also,
1700   // check to see that the recursive walk actually found our case statement.
1701   // Insane cases like this can fail to find it in the recursive walk since we
1702   // don't handle every stmt kind:
1703   // switch (4) {
1704   //   while (1) {
1705   //     case 4: ...
1706   bool FoundCase = false;
1707   ResultCase = Case;
1708   return CollectStatementsForCase(S.getBody(), Case, FoundCase,
1709                                   ResultStmts) != CSFC_Failure &&
1710          FoundCase;
1711 }
1712 
1713 static Optional<SmallVector<uint64_t, 16>>
1714 getLikelihoodWeights(ArrayRef<Stmt::Likelihood> Likelihoods) {
1715   // Are there enough branches to weight them?
1716   if (Likelihoods.size() <= 1)
1717     return None;
1718 
1719   uint64_t NumUnlikely = 0;
1720   uint64_t NumNone = 0;
1721   uint64_t NumLikely = 0;
1722   for (const auto LH : Likelihoods) {
1723     switch (LH) {
1724     case Stmt::LH_Unlikely:
1725       ++NumUnlikely;
1726       break;
1727     case Stmt::LH_None:
1728       ++NumNone;
1729       break;
1730     case Stmt::LH_Likely:
1731       ++NumLikely;
1732       break;
1733     }
1734   }
1735 
1736   // Is there a likelihood attribute used?
1737   if (NumUnlikely == 0 && NumLikely == 0)
1738     return None;
1739 
1740   // When multiple cases share the same code they can be combined during
1741   // optimization. In that case the weights of the branch will be the sum of
1742   // the individual weights. Make sure the combined sum of all neutral cases
1743   // doesn't exceed the value of a single likely attribute.
1744   // The additions both avoid divisions by 0 and make sure the weights of None
1745   // don't exceed the weight of Likely.
1746   const uint64_t Likely = INT32_MAX / (NumLikely + 2);
1747   const uint64_t None = Likely / (NumNone + 1);
1748   const uint64_t Unlikely = 0;
1749 
1750   SmallVector<uint64_t, 16> Result;
1751   Result.reserve(Likelihoods.size());
1752   for (const auto LH : Likelihoods) {
1753     switch (LH) {
1754     case Stmt::LH_Unlikely:
1755       Result.push_back(Unlikely);
1756       break;
1757     case Stmt::LH_None:
1758       Result.push_back(None);
1759       break;
1760     case Stmt::LH_Likely:
1761       Result.push_back(Likely);
1762       break;
1763     }
1764   }
1765 
1766   return Result;
1767 }
1768 
1769 void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) {
1770   // Handle nested switch statements.
1771   llvm::SwitchInst *SavedSwitchInsn = SwitchInsn;
1772   SmallVector<uint64_t, 16> *SavedSwitchWeights = SwitchWeights;
1773   SmallVector<Stmt::Likelihood, 16> *SavedSwitchLikelihood = SwitchLikelihood;
1774   llvm::BasicBlock *SavedCRBlock = CaseRangeBlock;
1775 
1776   // See if we can constant fold the condition of the switch and therefore only
1777   // emit the live case statement (if any) of the switch.
1778   llvm::APSInt ConstantCondValue;
1779   if (ConstantFoldsToSimpleInteger(S.getCond(), ConstantCondValue)) {
1780     SmallVector<const Stmt*, 4> CaseStmts;
1781     const SwitchCase *Case = nullptr;
1782     if (FindCaseStatementsForValue(S, ConstantCondValue, CaseStmts,
1783                                    getContext(), Case)) {
1784       if (Case)
1785         incrementProfileCounter(Case);
1786       RunCleanupsScope ExecutedScope(*this);
1787 
1788       if (S.getInit())
1789         EmitStmt(S.getInit());
1790 
1791       // Emit the condition variable if needed inside the entire cleanup scope
1792       // used by this special case for constant folded switches.
1793       if (S.getConditionVariable())
1794         EmitDecl(*S.getConditionVariable());
1795 
1796       // At this point, we are no longer "within" a switch instance, so
1797       // we can temporarily enforce this to ensure that any embedded case
1798       // statements are not emitted.
1799       SwitchInsn = nullptr;
1800 
1801       // Okay, we can dead code eliminate everything except this case.  Emit the
1802       // specified series of statements and we're good.
1803       for (unsigned i = 0, e = CaseStmts.size(); i != e; ++i)
1804         EmitStmt(CaseStmts[i]);
1805       incrementProfileCounter(&S);
1806 
1807       // Now we want to restore the saved switch instance so that nested
1808       // switches continue to function properly
1809       SwitchInsn = SavedSwitchInsn;
1810 
1811       return;
1812     }
1813   }
1814 
1815   JumpDest SwitchExit = getJumpDestInCurrentScope("sw.epilog");
1816 
1817   RunCleanupsScope ConditionScope(*this);
1818 
1819   if (S.getInit())
1820     EmitStmt(S.getInit());
1821 
1822   if (S.getConditionVariable())
1823     EmitDecl(*S.getConditionVariable());
1824   llvm::Value *CondV = EmitScalarExpr(S.getCond());
1825 
1826   // Create basic block to hold stuff that comes after switch
1827   // statement. We also need to create a default block now so that
1828   // explicit case ranges tests can have a place to jump to on
1829   // failure.
1830   llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default");
1831   SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock);
1832   if (PGO.haveRegionCounts()) {
1833     // Walk the SwitchCase list to find how many there are.
1834     uint64_t DefaultCount = 0;
1835     unsigned NumCases = 0;
1836     for (const SwitchCase *Case = S.getSwitchCaseList();
1837          Case;
1838          Case = Case->getNextSwitchCase()) {
1839       if (isa<DefaultStmt>(Case))
1840         DefaultCount = getProfileCount(Case);
1841       NumCases += 1;
1842     }
1843     SwitchWeights = new SmallVector<uint64_t, 16>();
1844     SwitchWeights->reserve(NumCases);
1845     // The default needs to be first. We store the edge count, so we already
1846     // know the right weight.
1847     SwitchWeights->push_back(DefaultCount);
1848   } else if (CGM.getCodeGenOpts().OptimizationLevel) {
1849     SwitchLikelihood = new SmallVector<Stmt::Likelihood, 16>();
1850     // Initialize the default case.
1851     SwitchLikelihood->push_back(Stmt::LH_None);
1852   }
1853 
1854   CaseRangeBlock = DefaultBlock;
1855 
1856   // Clear the insertion point to indicate we are in unreachable code.
1857   Builder.ClearInsertionPoint();
1858 
1859   // All break statements jump to NextBlock. If BreakContinueStack is non-empty
1860   // then reuse last ContinueBlock.
1861   JumpDest OuterContinue;
1862   if (!BreakContinueStack.empty())
1863     OuterContinue = BreakContinueStack.back().ContinueBlock;
1864 
1865   BreakContinueStack.push_back(BreakContinue(SwitchExit, OuterContinue));
1866 
1867   // Emit switch body.
1868   EmitStmt(S.getBody());
1869 
1870   BreakContinueStack.pop_back();
1871 
1872   // Update the default block in case explicit case range tests have
1873   // been chained on top.
1874   SwitchInsn->setDefaultDest(CaseRangeBlock);
1875 
1876   // If a default was never emitted:
1877   if (!DefaultBlock->getParent()) {
1878     // If we have cleanups, emit the default block so that there's a
1879     // place to jump through the cleanups from.
1880     if (ConditionScope.requiresCleanups()) {
1881       EmitBlock(DefaultBlock);
1882 
1883     // Otherwise, just forward the default block to the switch end.
1884     } else {
1885       DefaultBlock->replaceAllUsesWith(SwitchExit.getBlock());
1886       delete DefaultBlock;
1887     }
1888   }
1889 
1890   ConditionScope.ForceCleanup();
1891 
1892   // Emit continuation.
1893   EmitBlock(SwitchExit.getBlock(), true);
1894   incrementProfileCounter(&S);
1895 
1896   // If the switch has a condition wrapped by __builtin_unpredictable,
1897   // create metadata that specifies that the switch is unpredictable.
1898   // Don't bother if not optimizing because that metadata would not be used.
1899   auto *Call = dyn_cast<CallExpr>(S.getCond());
1900   if (Call && CGM.getCodeGenOpts().OptimizationLevel != 0) {
1901     auto *FD = dyn_cast_or_null<FunctionDecl>(Call->getCalleeDecl());
1902     if (FD && FD->getBuiltinID() == Builtin::BI__builtin_unpredictable) {
1903       llvm::MDBuilder MDHelper(getLLVMContext());
1904       SwitchInsn->setMetadata(llvm::LLVMContext::MD_unpredictable,
1905                               MDHelper.createUnpredictable());
1906     }
1907   }
1908 
1909   if (SwitchWeights) {
1910     assert(SwitchWeights->size() == 1 + SwitchInsn->getNumCases() &&
1911            "switch weights do not match switch cases");
1912     // If there's only one jump destination there's no sense weighting it.
1913     if (SwitchWeights->size() > 1)
1914       SwitchInsn->setMetadata(llvm::LLVMContext::MD_prof,
1915                               createProfileWeights(*SwitchWeights));
1916     delete SwitchWeights;
1917   } else if (SwitchLikelihood) {
1918     assert(SwitchLikelihood->size() == 1 + SwitchInsn->getNumCases() &&
1919            "switch likelihoods do not match switch cases");
1920     Optional<SmallVector<uint64_t, 16>> LHW =
1921         getLikelihoodWeights(*SwitchLikelihood);
1922     if (LHW) {
1923       llvm::MDBuilder MDHelper(CGM.getLLVMContext());
1924       SwitchInsn->setMetadata(llvm::LLVMContext::MD_prof,
1925                               createProfileWeights(*LHW));
1926     }
1927     delete SwitchLikelihood;
1928   }
1929   SwitchInsn = SavedSwitchInsn;
1930   SwitchWeights = SavedSwitchWeights;
1931   SwitchLikelihood = SavedSwitchLikelihood;
1932   CaseRangeBlock = SavedCRBlock;
1933 }
1934 
1935 static std::string
1936 SimplifyConstraint(const char *Constraint, const TargetInfo &Target,
1937                  SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=nullptr) {
1938   std::string Result;
1939 
1940   while (*Constraint) {
1941     switch (*Constraint) {
1942     default:
1943       Result += Target.convertConstraint(Constraint);
1944       break;
1945     // Ignore these
1946     case '*':
1947     case '?':
1948     case '!':
1949     case '=': // Will see this and the following in mult-alt constraints.
1950     case '+':
1951       break;
1952     case '#': // Ignore the rest of the constraint alternative.
1953       while (Constraint[1] && Constraint[1] != ',')
1954         Constraint++;
1955       break;
1956     case '&':
1957     case '%':
1958       Result += *Constraint;
1959       while (Constraint[1] && Constraint[1] == *Constraint)
1960         Constraint++;
1961       break;
1962     case ',':
1963       Result += "|";
1964       break;
1965     case 'g':
1966       Result += "imr";
1967       break;
1968     case '[': {
1969       assert(OutCons &&
1970              "Must pass output names to constraints with a symbolic name");
1971       unsigned Index;
1972       bool result = Target.resolveSymbolicName(Constraint, *OutCons, Index);
1973       assert(result && "Could not resolve symbolic name"); (void)result;
1974       Result += llvm::utostr(Index);
1975       break;
1976     }
1977     }
1978 
1979     Constraint++;
1980   }
1981 
1982   return Result;
1983 }
1984 
1985 /// AddVariableConstraints - Look at AsmExpr and if it is a variable declared
1986 /// as using a particular register add that as a constraint that will be used
1987 /// in this asm stmt.
1988 static std::string
1989 AddVariableConstraints(const std::string &Constraint, const Expr &AsmExpr,
1990                        const TargetInfo &Target, CodeGenModule &CGM,
1991                        const AsmStmt &Stmt, const bool EarlyClobber,
1992                        std::string *GCCReg = nullptr) {
1993   const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(&AsmExpr);
1994   if (!AsmDeclRef)
1995     return Constraint;
1996   const ValueDecl &Value = *AsmDeclRef->getDecl();
1997   const VarDecl *Variable = dyn_cast<VarDecl>(&Value);
1998   if (!Variable)
1999     return Constraint;
2000   if (Variable->getStorageClass() != SC_Register)
2001     return Constraint;
2002   AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>();
2003   if (!Attr)
2004     return Constraint;
2005   StringRef Register = Attr->getLabel();
2006   assert(Target.isValidGCCRegisterName(Register));
2007   // We're using validateOutputConstraint here because we only care if
2008   // this is a register constraint.
2009   TargetInfo::ConstraintInfo Info(Constraint, "");
2010   if (Target.validateOutputConstraint(Info) &&
2011       !Info.allowsRegister()) {
2012     CGM.ErrorUnsupported(&Stmt, "__asm__");
2013     return Constraint;
2014   }
2015   // Canonicalize the register here before returning it.
2016   Register = Target.getNormalizedGCCRegisterName(Register);
2017   if (GCCReg != nullptr)
2018     *GCCReg = Register.str();
2019   return (EarlyClobber ? "&{" : "{") + Register.str() + "}";
2020 }
2021 
2022 llvm::Value*
2023 CodeGenFunction::EmitAsmInputLValue(const TargetInfo::ConstraintInfo &Info,
2024                                     LValue InputValue, QualType InputType,
2025                                     std::string &ConstraintStr,
2026                                     SourceLocation Loc) {
2027   llvm::Value *Arg;
2028   if (Info.allowsRegister() || !Info.allowsMemory()) {
2029     if (CodeGenFunction::hasScalarEvaluationKind(InputType)) {
2030       Arg = EmitLoadOfLValue(InputValue, Loc).getScalarVal();
2031     } else {
2032       llvm::Type *Ty = ConvertType(InputType);
2033       uint64_t Size = CGM.getDataLayout().getTypeSizeInBits(Ty);
2034       if (Size <= 64 && llvm::isPowerOf2_64(Size)) {
2035         Ty = llvm::IntegerType::get(getLLVMContext(), Size);
2036         Ty = llvm::PointerType::getUnqual(Ty);
2037 
2038         Arg = Builder.CreateLoad(
2039             Builder.CreateBitCast(InputValue.getAddress(*this), Ty));
2040       } else {
2041         Arg = InputValue.getPointer(*this);
2042         ConstraintStr += '*';
2043       }
2044     }
2045   } else {
2046     Arg = InputValue.getPointer(*this);
2047     ConstraintStr += '*';
2048   }
2049 
2050   return Arg;
2051 }
2052 
2053 llvm::Value* CodeGenFunction::EmitAsmInput(
2054                                          const TargetInfo::ConstraintInfo &Info,
2055                                            const Expr *InputExpr,
2056                                            std::string &ConstraintStr) {
2057   // If this can't be a register or memory, i.e., has to be a constant
2058   // (immediate or symbolic), try to emit it as such.
2059   if (!Info.allowsRegister() && !Info.allowsMemory()) {
2060     if (Info.requiresImmediateConstant()) {
2061       Expr::EvalResult EVResult;
2062       InputExpr->EvaluateAsRValue(EVResult, getContext(), true);
2063 
2064       llvm::APSInt IntResult;
2065       if (EVResult.Val.toIntegralConstant(IntResult, InputExpr->getType(),
2066                                           getContext()))
2067         return llvm::ConstantInt::get(getLLVMContext(), IntResult);
2068     }
2069 
2070     Expr::EvalResult Result;
2071     if (InputExpr->EvaluateAsInt(Result, getContext()))
2072       return llvm::ConstantInt::get(getLLVMContext(), Result.Val.getInt());
2073   }
2074 
2075   if (Info.allowsRegister() || !Info.allowsMemory())
2076     if (CodeGenFunction::hasScalarEvaluationKind(InputExpr->getType()))
2077       return EmitScalarExpr(InputExpr);
2078   if (InputExpr->getStmtClass() == Expr::CXXThisExprClass)
2079     return EmitScalarExpr(InputExpr);
2080   InputExpr = InputExpr->IgnoreParenNoopCasts(getContext());
2081   LValue Dest = EmitLValue(InputExpr);
2082   return EmitAsmInputLValue(Info, Dest, InputExpr->getType(), ConstraintStr,
2083                             InputExpr->getExprLoc());
2084 }
2085 
2086 /// getAsmSrcLocInfo - Return the !srcloc metadata node to attach to an inline
2087 /// asm call instruction.  The !srcloc MDNode contains a list of constant
2088 /// integers which are the source locations of the start of each line in the
2089 /// asm.
2090 static llvm::MDNode *getAsmSrcLocInfo(const StringLiteral *Str,
2091                                       CodeGenFunction &CGF) {
2092   SmallVector<llvm::Metadata *, 8> Locs;
2093   // Add the location of the first line to the MDNode.
2094   Locs.push_back(llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
2095       CGF.Int32Ty, Str->getBeginLoc().getRawEncoding())));
2096   StringRef StrVal = Str->getString();
2097   if (!StrVal.empty()) {
2098     const SourceManager &SM = CGF.CGM.getContext().getSourceManager();
2099     const LangOptions &LangOpts = CGF.CGM.getLangOpts();
2100     unsigned StartToken = 0;
2101     unsigned ByteOffset = 0;
2102 
2103     // Add the location of the start of each subsequent line of the asm to the
2104     // MDNode.
2105     for (unsigned i = 0, e = StrVal.size() - 1; i != e; ++i) {
2106       if (StrVal[i] != '\n') continue;
2107       SourceLocation LineLoc = Str->getLocationOfByte(
2108           i + 1, SM, LangOpts, CGF.getTarget(), &StartToken, &ByteOffset);
2109       Locs.push_back(llvm::ConstantAsMetadata::get(
2110           llvm::ConstantInt::get(CGF.Int32Ty, LineLoc.getRawEncoding())));
2111     }
2112   }
2113 
2114   return llvm::MDNode::get(CGF.getLLVMContext(), Locs);
2115 }
2116 
2117 static void UpdateAsmCallInst(llvm::CallBase &Result, bool HasSideEffect,
2118                               bool ReadOnly, bool ReadNone, bool NoMerge,
2119                               const AsmStmt &S,
2120                               const std::vector<llvm::Type *> &ResultRegTypes,
2121                               CodeGenFunction &CGF,
2122                               std::vector<llvm::Value *> &RegResults) {
2123   Result.addAttribute(llvm::AttributeList::FunctionIndex,
2124                       llvm::Attribute::NoUnwind);
2125   if (NoMerge)
2126     Result.addAttribute(llvm::AttributeList::FunctionIndex,
2127                         llvm::Attribute::NoMerge);
2128   // Attach readnone and readonly attributes.
2129   if (!HasSideEffect) {
2130     if (ReadNone)
2131       Result.addAttribute(llvm::AttributeList::FunctionIndex,
2132                           llvm::Attribute::ReadNone);
2133     else if (ReadOnly)
2134       Result.addAttribute(llvm::AttributeList::FunctionIndex,
2135                           llvm::Attribute::ReadOnly);
2136   }
2137 
2138   // Slap the source location of the inline asm into a !srcloc metadata on the
2139   // call.
2140   if (const auto *gccAsmStmt = dyn_cast<GCCAsmStmt>(&S))
2141     Result.setMetadata("srcloc",
2142                        getAsmSrcLocInfo(gccAsmStmt->getAsmString(), CGF));
2143   else {
2144     // At least put the line number on MS inline asm blobs.
2145     llvm::Constant *Loc = llvm::ConstantInt::get(CGF.Int32Ty,
2146                                         S.getAsmLoc().getRawEncoding());
2147     Result.setMetadata("srcloc",
2148                        llvm::MDNode::get(CGF.getLLVMContext(),
2149                                          llvm::ConstantAsMetadata::get(Loc)));
2150   }
2151 
2152   if (CGF.getLangOpts().assumeFunctionsAreConvergent())
2153     // Conservatively, mark all inline asm blocks in CUDA or OpenCL as
2154     // convergent (meaning, they may call an intrinsically convergent op, such
2155     // as bar.sync, and so can't have certain optimizations applied around
2156     // them).
2157     Result.addAttribute(llvm::AttributeList::FunctionIndex,
2158                         llvm::Attribute::Convergent);
2159   // Extract all of the register value results from the asm.
2160   if (ResultRegTypes.size() == 1) {
2161     RegResults.push_back(&Result);
2162   } else {
2163     for (unsigned i = 0, e = ResultRegTypes.size(); i != e; ++i) {
2164       llvm::Value *Tmp = CGF.Builder.CreateExtractValue(&Result, i, "asmresult");
2165       RegResults.push_back(Tmp);
2166     }
2167   }
2168 }
2169 
2170 void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {
2171   // Assemble the final asm string.
2172   std::string AsmString = S.generateAsmString(getContext());
2173 
2174   // Get all the output and input constraints together.
2175   SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
2176   SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
2177 
2178   for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) {
2179     StringRef Name;
2180     if (const GCCAsmStmt *GAS = dyn_cast<GCCAsmStmt>(&S))
2181       Name = GAS->getOutputName(i);
2182     TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), Name);
2183     bool IsValid = getTarget().validateOutputConstraint(Info); (void)IsValid;
2184     assert(IsValid && "Failed to parse output constraint");
2185     OutputConstraintInfos.push_back(Info);
2186   }
2187 
2188   for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) {
2189     StringRef Name;
2190     if (const GCCAsmStmt *GAS = dyn_cast<GCCAsmStmt>(&S))
2191       Name = GAS->getInputName(i);
2192     TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), Name);
2193     bool IsValid =
2194       getTarget().validateInputConstraint(OutputConstraintInfos, Info);
2195     assert(IsValid && "Failed to parse input constraint"); (void)IsValid;
2196     InputConstraintInfos.push_back(Info);
2197   }
2198 
2199   std::string Constraints;
2200 
2201   std::vector<LValue> ResultRegDests;
2202   std::vector<QualType> ResultRegQualTys;
2203   std::vector<llvm::Type *> ResultRegTypes;
2204   std::vector<llvm::Type *> ResultTruncRegTypes;
2205   std::vector<llvm::Type *> ArgTypes;
2206   std::vector<llvm::Value*> Args;
2207   llvm::BitVector ResultTypeRequiresCast;
2208 
2209   // Keep track of inout constraints.
2210   std::string InOutConstraints;
2211   std::vector<llvm::Value*> InOutArgs;
2212   std::vector<llvm::Type*> InOutArgTypes;
2213 
2214   // Keep track of out constraints for tied input operand.
2215   std::vector<std::string> OutputConstraints;
2216 
2217   // Keep track of defined physregs.
2218   llvm::SmallSet<std::string, 8> PhysRegOutputs;
2219 
2220   // An inline asm can be marked readonly if it meets the following conditions:
2221   //  - it doesn't have any sideeffects
2222   //  - it doesn't clobber memory
2223   //  - it doesn't return a value by-reference
2224   // It can be marked readnone if it doesn't have any input memory constraints
2225   // in addition to meeting the conditions listed above.
2226   bool ReadOnly = true, ReadNone = true;
2227 
2228   for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) {
2229     TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];
2230 
2231     // Simplify the output constraint.
2232     std::string OutputConstraint(S.getOutputConstraint(i));
2233     OutputConstraint = SimplifyConstraint(OutputConstraint.c_str() + 1,
2234                                           getTarget(), &OutputConstraintInfos);
2235 
2236     const Expr *OutExpr = S.getOutputExpr(i);
2237     OutExpr = OutExpr->IgnoreParenNoopCasts(getContext());
2238 
2239     std::string GCCReg;
2240     OutputConstraint = AddVariableConstraints(OutputConstraint, *OutExpr,
2241                                               getTarget(), CGM, S,
2242                                               Info.earlyClobber(),
2243                                               &GCCReg);
2244     // Give an error on multiple outputs to same physreg.
2245     if (!GCCReg.empty() && !PhysRegOutputs.insert(GCCReg).second)
2246       CGM.Error(S.getAsmLoc(), "multiple outputs to hard register: " + GCCReg);
2247 
2248     OutputConstraints.push_back(OutputConstraint);
2249     LValue Dest = EmitLValue(OutExpr);
2250     if (!Constraints.empty())
2251       Constraints += ',';
2252 
2253     // If this is a register output, then make the inline asm return it
2254     // by-value.  If this is a memory result, return the value by-reference.
2255     bool isScalarizableAggregate =
2256         hasAggregateEvaluationKind(OutExpr->getType());
2257     if (!Info.allowsMemory() && (hasScalarEvaluationKind(OutExpr->getType()) ||
2258                                  isScalarizableAggregate)) {
2259       Constraints += "=" + OutputConstraint;
2260       ResultRegQualTys.push_back(OutExpr->getType());
2261       ResultRegDests.push_back(Dest);
2262       ResultTruncRegTypes.push_back(ConvertTypeForMem(OutExpr->getType()));
2263       if (Info.allowsRegister() && isScalarizableAggregate) {
2264         ResultTypeRequiresCast.push_back(true);
2265         unsigned Size = getContext().getTypeSize(OutExpr->getType());
2266         llvm::Type *ConvTy = llvm::IntegerType::get(getLLVMContext(), Size);
2267         ResultRegTypes.push_back(ConvTy);
2268       } else {
2269         ResultTypeRequiresCast.push_back(false);
2270         ResultRegTypes.push_back(ResultTruncRegTypes.back());
2271       }
2272       // If this output is tied to an input, and if the input is larger, then
2273       // we need to set the actual result type of the inline asm node to be the
2274       // same as the input type.
2275       if (Info.hasMatchingInput()) {
2276         unsigned InputNo;
2277         for (InputNo = 0; InputNo != S.getNumInputs(); ++InputNo) {
2278           TargetInfo::ConstraintInfo &Input = InputConstraintInfos[InputNo];
2279           if (Input.hasTiedOperand() && Input.getTiedOperand() == i)
2280             break;
2281         }
2282         assert(InputNo != S.getNumInputs() && "Didn't find matching input!");
2283 
2284         QualType InputTy = S.getInputExpr(InputNo)->getType();
2285         QualType OutputType = OutExpr->getType();
2286 
2287         uint64_t InputSize = getContext().getTypeSize(InputTy);
2288         if (getContext().getTypeSize(OutputType) < InputSize) {
2289           // Form the asm to return the value as a larger integer or fp type.
2290           ResultRegTypes.back() = ConvertType(InputTy);
2291         }
2292       }
2293       if (llvm::Type* AdjTy =
2294             getTargetHooks().adjustInlineAsmType(*this, OutputConstraint,
2295                                                  ResultRegTypes.back()))
2296         ResultRegTypes.back() = AdjTy;
2297       else {
2298         CGM.getDiags().Report(S.getAsmLoc(),
2299                               diag::err_asm_invalid_type_in_input)
2300             << OutExpr->getType() << OutputConstraint;
2301       }
2302 
2303       // Update largest vector width for any vector types.
2304       if (auto *VT = dyn_cast<llvm::VectorType>(ResultRegTypes.back()))
2305         LargestVectorWidth =
2306             std::max((uint64_t)LargestVectorWidth,
2307                      VT->getPrimitiveSizeInBits().getKnownMinSize());
2308     } else {
2309       llvm::Type *DestAddrTy = Dest.getAddress(*this).getType();
2310       llvm::Value *DestPtr = Dest.getPointer(*this);
2311       // Matrix types in memory are represented by arrays, but accessed through
2312       // vector pointers, with the alignment specified on the access operation.
2313       // For inline assembly, update pointer arguments to use vector pointers.
2314       // Otherwise there will be a mis-match if the matrix is also an
2315       // input-argument which is represented as vector.
2316       if (isa<MatrixType>(OutExpr->getType().getCanonicalType())) {
2317         DestAddrTy = llvm::PointerType::get(
2318             ConvertType(OutExpr->getType()),
2319             cast<llvm::PointerType>(DestAddrTy)->getAddressSpace());
2320         DestPtr = Builder.CreateBitCast(DestPtr, DestAddrTy);
2321       }
2322       ArgTypes.push_back(DestAddrTy);
2323       Args.push_back(DestPtr);
2324       Constraints += "=*";
2325       Constraints += OutputConstraint;
2326       ReadOnly = ReadNone = false;
2327     }
2328 
2329     if (Info.isReadWrite()) {
2330       InOutConstraints += ',';
2331 
2332       const Expr *InputExpr = S.getOutputExpr(i);
2333       llvm::Value *Arg = EmitAsmInputLValue(Info, Dest, InputExpr->getType(),
2334                                             InOutConstraints,
2335                                             InputExpr->getExprLoc());
2336 
2337       if (llvm::Type* AdjTy =
2338           getTargetHooks().adjustInlineAsmType(*this, OutputConstraint,
2339                                                Arg->getType()))
2340         Arg = Builder.CreateBitCast(Arg, AdjTy);
2341 
2342       // Update largest vector width for any vector types.
2343       if (auto *VT = dyn_cast<llvm::VectorType>(Arg->getType()))
2344         LargestVectorWidth =
2345             std::max((uint64_t)LargestVectorWidth,
2346                      VT->getPrimitiveSizeInBits().getKnownMinSize());
2347       // Only tie earlyclobber physregs.
2348       if (Info.allowsRegister() && (GCCReg.empty() || Info.earlyClobber()))
2349         InOutConstraints += llvm::utostr(i);
2350       else
2351         InOutConstraints += OutputConstraint;
2352 
2353       InOutArgTypes.push_back(Arg->getType());
2354       InOutArgs.push_back(Arg);
2355     }
2356   }
2357 
2358   // If this is a Microsoft-style asm blob, store the return registers (EAX:EDX)
2359   // to the return value slot. Only do this when returning in registers.
2360   if (isa<MSAsmStmt>(&S)) {
2361     const ABIArgInfo &RetAI = CurFnInfo->getReturnInfo();
2362     if (RetAI.isDirect() || RetAI.isExtend()) {
2363       // Make a fake lvalue for the return value slot.
2364       LValue ReturnSlot = MakeAddrLValue(ReturnValue, FnRetTy);
2365       CGM.getTargetCodeGenInfo().addReturnRegisterOutputs(
2366           *this, ReturnSlot, Constraints, ResultRegTypes, ResultTruncRegTypes,
2367           ResultRegDests, AsmString, S.getNumOutputs());
2368       SawAsmBlock = true;
2369     }
2370   }
2371 
2372   for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) {
2373     const Expr *InputExpr = S.getInputExpr(i);
2374 
2375     TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
2376 
2377     if (Info.allowsMemory())
2378       ReadNone = false;
2379 
2380     if (!Constraints.empty())
2381       Constraints += ',';
2382 
2383     // Simplify the input constraint.
2384     std::string InputConstraint(S.getInputConstraint(i));
2385     InputConstraint = SimplifyConstraint(InputConstraint.c_str(), getTarget(),
2386                                          &OutputConstraintInfos);
2387 
2388     InputConstraint = AddVariableConstraints(
2389         InputConstraint, *InputExpr->IgnoreParenNoopCasts(getContext()),
2390         getTarget(), CGM, S, false /* No EarlyClobber */);
2391 
2392     std::string ReplaceConstraint (InputConstraint);
2393     llvm::Value *Arg = EmitAsmInput(Info, InputExpr, Constraints);
2394 
2395     // If this input argument is tied to a larger output result, extend the
2396     // input to be the same size as the output.  The LLVM backend wants to see
2397     // the input and output of a matching constraint be the same size.  Note
2398     // that GCC does not define what the top bits are here.  We use zext because
2399     // that is usually cheaper, but LLVM IR should really get an anyext someday.
2400     if (Info.hasTiedOperand()) {
2401       unsigned Output = Info.getTiedOperand();
2402       QualType OutputType = S.getOutputExpr(Output)->getType();
2403       QualType InputTy = InputExpr->getType();
2404 
2405       if (getContext().getTypeSize(OutputType) >
2406           getContext().getTypeSize(InputTy)) {
2407         // Use ptrtoint as appropriate so that we can do our extension.
2408         if (isa<llvm::PointerType>(Arg->getType()))
2409           Arg = Builder.CreatePtrToInt(Arg, IntPtrTy);
2410         llvm::Type *OutputTy = ConvertType(OutputType);
2411         if (isa<llvm::IntegerType>(OutputTy))
2412           Arg = Builder.CreateZExt(Arg, OutputTy);
2413         else if (isa<llvm::PointerType>(OutputTy))
2414           Arg = Builder.CreateZExt(Arg, IntPtrTy);
2415         else {
2416           assert(OutputTy->isFloatingPointTy() && "Unexpected output type");
2417           Arg = Builder.CreateFPExt(Arg, OutputTy);
2418         }
2419       }
2420       // Deal with the tied operands' constraint code in adjustInlineAsmType.
2421       ReplaceConstraint = OutputConstraints[Output];
2422     }
2423     if (llvm::Type* AdjTy =
2424           getTargetHooks().adjustInlineAsmType(*this, ReplaceConstraint,
2425                                                    Arg->getType()))
2426       Arg = Builder.CreateBitCast(Arg, AdjTy);
2427     else
2428       CGM.getDiags().Report(S.getAsmLoc(), diag::err_asm_invalid_type_in_input)
2429           << InputExpr->getType() << InputConstraint;
2430 
2431     // Update largest vector width for any vector types.
2432     if (auto *VT = dyn_cast<llvm::VectorType>(Arg->getType()))
2433       LargestVectorWidth =
2434           std::max((uint64_t)LargestVectorWidth,
2435                    VT->getPrimitiveSizeInBits().getKnownMinSize());
2436 
2437     ArgTypes.push_back(Arg->getType());
2438     Args.push_back(Arg);
2439     Constraints += InputConstraint;
2440   }
2441 
2442   // Labels
2443   SmallVector<llvm::BasicBlock *, 16> Transfer;
2444   llvm::BasicBlock *Fallthrough = nullptr;
2445   bool IsGCCAsmGoto = false;
2446   if (const auto *GS =  dyn_cast<GCCAsmStmt>(&S)) {
2447     IsGCCAsmGoto = GS->isAsmGoto();
2448     if (IsGCCAsmGoto) {
2449       for (const auto *E : GS->labels()) {
2450         JumpDest Dest = getJumpDestForLabel(E->getLabel());
2451         Transfer.push_back(Dest.getBlock());
2452         llvm::BlockAddress *BA =
2453             llvm::BlockAddress::get(CurFn, Dest.getBlock());
2454         Args.push_back(BA);
2455         ArgTypes.push_back(BA->getType());
2456         if (!Constraints.empty())
2457           Constraints += ',';
2458         Constraints += 'X';
2459       }
2460       Fallthrough = createBasicBlock("asm.fallthrough");
2461     }
2462   }
2463 
2464   // Append the "input" part of inout constraints last.
2465   for (unsigned i = 0, e = InOutArgs.size(); i != e; i++) {
2466     ArgTypes.push_back(InOutArgTypes[i]);
2467     Args.push_back(InOutArgs[i]);
2468   }
2469   Constraints += InOutConstraints;
2470 
2471   // Clobbers
2472   for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) {
2473     StringRef Clobber = S.getClobber(i);
2474 
2475     if (Clobber == "memory")
2476       ReadOnly = ReadNone = false;
2477     else if (Clobber != "cc") {
2478       Clobber = getTarget().getNormalizedGCCRegisterName(Clobber);
2479       if (CGM.getCodeGenOpts().StackClashProtector &&
2480           getTarget().isSPRegName(Clobber)) {
2481         CGM.getDiags().Report(S.getAsmLoc(),
2482                               diag::warn_stack_clash_protection_inline_asm);
2483       }
2484     }
2485 
2486     if (!Constraints.empty())
2487       Constraints += ',';
2488 
2489     Constraints += "~{";
2490     Constraints += Clobber;
2491     Constraints += '}';
2492   }
2493 
2494   // Add machine specific clobbers
2495   std::string MachineClobbers = getTarget().getClobbers();
2496   if (!MachineClobbers.empty()) {
2497     if (!Constraints.empty())
2498       Constraints += ',';
2499     Constraints += MachineClobbers;
2500   }
2501 
2502   llvm::Type *ResultType;
2503   if (ResultRegTypes.empty())
2504     ResultType = VoidTy;
2505   else if (ResultRegTypes.size() == 1)
2506     ResultType = ResultRegTypes[0];
2507   else
2508     ResultType = llvm::StructType::get(getLLVMContext(), ResultRegTypes);
2509 
2510   llvm::FunctionType *FTy =
2511     llvm::FunctionType::get(ResultType, ArgTypes, false);
2512 
2513   bool HasSideEffect = S.isVolatile() || S.getNumOutputs() == 0;
2514   llvm::InlineAsm::AsmDialect AsmDialect = isa<MSAsmStmt>(&S) ?
2515     llvm::InlineAsm::AD_Intel : llvm::InlineAsm::AD_ATT;
2516   llvm::InlineAsm *IA =
2517     llvm::InlineAsm::get(FTy, AsmString, Constraints, HasSideEffect,
2518                          /* IsAlignStack */ false, AsmDialect);
2519   std::vector<llvm::Value*> RegResults;
2520   if (IsGCCAsmGoto) {
2521     llvm::CallBrInst *Result =
2522         Builder.CreateCallBr(IA, Fallthrough, Transfer, Args);
2523     EmitBlock(Fallthrough);
2524     UpdateAsmCallInst(cast<llvm::CallBase>(*Result), HasSideEffect, ReadOnly,
2525                       ReadNone, InNoMergeAttributedStmt, S, ResultRegTypes,
2526                       *this, RegResults);
2527   } else {
2528     llvm::CallInst *Result =
2529         Builder.CreateCall(IA, Args, getBundlesForFunclet(IA));
2530     UpdateAsmCallInst(cast<llvm::CallBase>(*Result), HasSideEffect, ReadOnly,
2531                       ReadNone, InNoMergeAttributedStmt, S, ResultRegTypes,
2532                       *this, RegResults);
2533   }
2534 
2535   assert(RegResults.size() == ResultRegTypes.size());
2536   assert(RegResults.size() == ResultTruncRegTypes.size());
2537   assert(RegResults.size() == ResultRegDests.size());
2538   // ResultRegDests can be also populated by addReturnRegisterOutputs() above,
2539   // in which case its size may grow.
2540   assert(ResultTypeRequiresCast.size() <= ResultRegDests.size());
2541   for (unsigned i = 0, e = RegResults.size(); i != e; ++i) {
2542     llvm::Value *Tmp = RegResults[i];
2543 
2544     // If the result type of the LLVM IR asm doesn't match the result type of
2545     // the expression, do the conversion.
2546     if (ResultRegTypes[i] != ResultTruncRegTypes[i]) {
2547       llvm::Type *TruncTy = ResultTruncRegTypes[i];
2548 
2549       // Truncate the integer result to the right size, note that TruncTy can be
2550       // a pointer.
2551       if (TruncTy->isFloatingPointTy())
2552         Tmp = Builder.CreateFPTrunc(Tmp, TruncTy);
2553       else if (TruncTy->isPointerTy() && Tmp->getType()->isIntegerTy()) {
2554         uint64_t ResSize = CGM.getDataLayout().getTypeSizeInBits(TruncTy);
2555         Tmp = Builder.CreateTrunc(Tmp,
2556                    llvm::IntegerType::get(getLLVMContext(), (unsigned)ResSize));
2557         Tmp = Builder.CreateIntToPtr(Tmp, TruncTy);
2558       } else if (Tmp->getType()->isPointerTy() && TruncTy->isIntegerTy()) {
2559         uint64_t TmpSize =CGM.getDataLayout().getTypeSizeInBits(Tmp->getType());
2560         Tmp = Builder.CreatePtrToInt(Tmp,
2561                    llvm::IntegerType::get(getLLVMContext(), (unsigned)TmpSize));
2562         Tmp = Builder.CreateTrunc(Tmp, TruncTy);
2563       } else if (TruncTy->isIntegerTy()) {
2564         Tmp = Builder.CreateZExtOrTrunc(Tmp, TruncTy);
2565       } else if (TruncTy->isVectorTy()) {
2566         Tmp = Builder.CreateBitCast(Tmp, TruncTy);
2567       }
2568     }
2569 
2570     LValue Dest = ResultRegDests[i];
2571     // ResultTypeRequiresCast elements correspond to the first
2572     // ResultTypeRequiresCast.size() elements of RegResults.
2573     if ((i < ResultTypeRequiresCast.size()) && ResultTypeRequiresCast[i]) {
2574       unsigned Size = getContext().getTypeSize(ResultRegQualTys[i]);
2575       Address A = Builder.CreateBitCast(Dest.getAddress(*this),
2576                                         ResultRegTypes[i]->getPointerTo());
2577       QualType Ty = getContext().getIntTypeForBitwidth(Size, /*Signed*/ false);
2578       if (Ty.isNull()) {
2579         const Expr *OutExpr = S.getOutputExpr(i);
2580         CGM.Error(
2581             OutExpr->getExprLoc(),
2582             "impossible constraint in asm: can't store value into a register");
2583         return;
2584       }
2585       Dest = MakeAddrLValue(A, Ty);
2586     }
2587     EmitStoreThroughLValue(RValue::get(Tmp), Dest);
2588   }
2589 }
2590 
2591 LValue CodeGenFunction::InitCapturedStruct(const CapturedStmt &S) {
2592   const RecordDecl *RD = S.getCapturedRecordDecl();
2593   QualType RecordTy = getContext().getRecordType(RD);
2594 
2595   // Initialize the captured struct.
2596   LValue SlotLV =
2597     MakeAddrLValue(CreateMemTemp(RecordTy, "agg.captured"), RecordTy);
2598 
2599   RecordDecl::field_iterator CurField = RD->field_begin();
2600   for (CapturedStmt::const_capture_init_iterator I = S.capture_init_begin(),
2601                                                  E = S.capture_init_end();
2602        I != E; ++I, ++CurField) {
2603     LValue LV = EmitLValueForFieldInitialization(SlotLV, *CurField);
2604     if (CurField->hasCapturedVLAType()) {
2605       EmitLambdaVLACapture(CurField->getCapturedVLAType(), LV);
2606     } else {
2607       EmitInitializerForField(*CurField, LV, *I);
2608     }
2609   }
2610 
2611   return SlotLV;
2612 }
2613 
2614 /// Generate an outlined function for the body of a CapturedStmt, store any
2615 /// captured variables into the captured struct, and call the outlined function.
2616 llvm::Function *
2617 CodeGenFunction::EmitCapturedStmt(const CapturedStmt &S, CapturedRegionKind K) {
2618   LValue CapStruct = InitCapturedStruct(S);
2619 
2620   // Emit the CapturedDecl
2621   CodeGenFunction CGF(CGM, true);
2622   CGCapturedStmtRAII CapInfoRAII(CGF, new CGCapturedStmtInfo(S, K));
2623   llvm::Function *F = CGF.GenerateCapturedStmtFunction(S);
2624   delete CGF.CapturedStmtInfo;
2625 
2626   // Emit call to the helper function.
2627   EmitCallOrInvoke(F, CapStruct.getPointer(*this));
2628 
2629   return F;
2630 }
2631 
2632 Address CodeGenFunction::GenerateCapturedStmtArgument(const CapturedStmt &S) {
2633   LValue CapStruct = InitCapturedStruct(S);
2634   return CapStruct.getAddress(*this);
2635 }
2636 
2637 /// Creates the outlined function for a CapturedStmt.
2638 llvm::Function *
2639 CodeGenFunction::GenerateCapturedStmtFunction(const CapturedStmt &S) {
2640   assert(CapturedStmtInfo &&
2641     "CapturedStmtInfo should be set when generating the captured function");
2642   const CapturedDecl *CD = S.getCapturedDecl();
2643   const RecordDecl *RD = S.getCapturedRecordDecl();
2644   SourceLocation Loc = S.getBeginLoc();
2645   assert(CD->hasBody() && "missing CapturedDecl body");
2646 
2647   // Build the argument list.
2648   ASTContext &Ctx = CGM.getContext();
2649   FunctionArgList Args;
2650   Args.append(CD->param_begin(), CD->param_end());
2651 
2652   // Create the function declaration.
2653   const CGFunctionInfo &FuncInfo =
2654     CGM.getTypes().arrangeBuiltinFunctionDeclaration(Ctx.VoidTy, Args);
2655   llvm::FunctionType *FuncLLVMTy = CGM.getTypes().GetFunctionType(FuncInfo);
2656 
2657   llvm::Function *F =
2658     llvm::Function::Create(FuncLLVMTy, llvm::GlobalValue::InternalLinkage,
2659                            CapturedStmtInfo->getHelperName(), &CGM.getModule());
2660   CGM.SetInternalFunctionAttributes(CD, F, FuncInfo);
2661   if (CD->isNothrow())
2662     F->addFnAttr(llvm::Attribute::NoUnwind);
2663 
2664   // Generate the function.
2665   StartFunction(CD, Ctx.VoidTy, F, FuncInfo, Args, CD->getLocation(),
2666                 CD->getBody()->getBeginLoc());
2667   // Set the context parameter in CapturedStmtInfo.
2668   Address DeclPtr = GetAddrOfLocalVar(CD->getContextParam());
2669   CapturedStmtInfo->setContextValue(Builder.CreateLoad(DeclPtr));
2670 
2671   // Initialize variable-length arrays.
2672   LValue Base = MakeNaturalAlignAddrLValue(CapturedStmtInfo->getContextValue(),
2673                                            Ctx.getTagDeclType(RD));
2674   for (auto *FD : RD->fields()) {
2675     if (FD->hasCapturedVLAType()) {
2676       auto *ExprArg =
2677           EmitLoadOfLValue(EmitLValueForField(Base, FD), S.getBeginLoc())
2678               .getScalarVal();
2679       auto VAT = FD->getCapturedVLAType();
2680       VLASizeMap[VAT->getSizeExpr()] = ExprArg;
2681     }
2682   }
2683 
2684   // If 'this' is captured, load it into CXXThisValue.
2685   if (CapturedStmtInfo->isCXXThisExprCaptured()) {
2686     FieldDecl *FD = CapturedStmtInfo->getThisFieldDecl();
2687     LValue ThisLValue = EmitLValueForField(Base, FD);
2688     CXXThisValue = EmitLoadOfLValue(ThisLValue, Loc).getScalarVal();
2689   }
2690 
2691   PGO.assignRegionCounters(GlobalDecl(CD), F);
2692   CapturedStmtInfo->EmitBody(*this, CD->getBody());
2693   FinishFunction(CD->getBodyRBrace());
2694 
2695   return F;
2696 }
2697