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/Expr.h"
20 #include "clang/AST/Stmt.h"
21 #include "clang/AST/StmtVisitor.h"
22 #include "clang/Basic/Builtins.h"
23 #include "clang/Basic/DiagnosticSema.h"
24 #include "clang/Basic/PrettyStackTrace.h"
25 #include "clang/Basic/SourceManager.h"
26 #include "clang/Basic/TargetInfo.h"
27 #include "llvm/ADT/SmallSet.h"
28 #include "llvm/ADT/StringExtras.h"
29 #include "llvm/IR/Assumptions.h"
30 #include "llvm/IR/DataLayout.h"
31 #include "llvm/IR/InlineAsm.h"
32 #include "llvm/IR/Intrinsics.h"
33 #include "llvm/IR/MDBuilder.h"
34 #include "llvm/Support/SaveAndRestore.h"
35 
36 using namespace clang;
37 using namespace CodeGen;
38 
39 //===----------------------------------------------------------------------===//
40 //                              Statement Emission
41 //===----------------------------------------------------------------------===//
42 
EmitStopPoint(const Stmt * S)43 void CodeGenFunction::EmitStopPoint(const Stmt *S) {
44   if (CGDebugInfo *DI = getDebugInfo()) {
45     SourceLocation Loc;
46     Loc = S->getBeginLoc();
47     DI->EmitLocation(Builder, Loc);
48 
49     LastStopPoint = Loc;
50   }
51 }
52 
EmitStmt(const Stmt * S,ArrayRef<const Attr * > Attrs)53 void CodeGenFunction::EmitStmt(const Stmt *S, ArrayRef<const Attr *> Attrs) {
54   assert(S && "Null statement?");
55   PGO.setCurrentStmt(S);
56 
57   // These statements have their own debug info handling.
58   if (EmitSimpleStmt(S, Attrs))
59     return;
60 
61   // Check if we are generating unreachable code.
62   if (!HaveInsertPoint()) {
63     // If so, and the statement doesn't contain a label, then we do not need to
64     // generate actual code. This is safe because (1) the current point is
65     // unreachable, so we don't need to execute the code, and (2) we've already
66     // handled the statements which update internal data structures (like the
67     // local variable map) which could be used by subsequent statements.
68     if (!ContainsLabel(S)) {
69       // Verify that any decl statements were handled as simple, they may be in
70       // scope of subsequent reachable statements.
71       assert(!isa<DeclStmt>(*S) && "Unexpected DeclStmt!");
72       return;
73     }
74 
75     // Otherwise, make a new block to hold the code.
76     EnsureInsertPoint();
77   }
78 
79   // Generate a stoppoint if we are emitting debug info.
80   EmitStopPoint(S);
81 
82   // Ignore all OpenMP directives except for simd if OpenMP with Simd is
83   // enabled.
84   if (getLangOpts().OpenMP && getLangOpts().OpenMPSimd) {
85     if (const auto *D = dyn_cast<OMPExecutableDirective>(S)) {
86       EmitSimpleOMPExecutableDirective(*D);
87       return;
88     }
89   }
90 
91   switch (S->getStmtClass()) {
92   case Stmt::NoStmtClass:
93   case Stmt::CXXCatchStmtClass:
94   case Stmt::SEHExceptStmtClass:
95   case Stmt::SEHFinallyStmtClass:
96   case Stmt::MSDependentExistsStmtClass:
97     llvm_unreachable("invalid statement class to emit generically");
98   case Stmt::NullStmtClass:
99   case Stmt::CompoundStmtClass:
100   case Stmt::DeclStmtClass:
101   case Stmt::LabelStmtClass:
102   case Stmt::AttributedStmtClass:
103   case Stmt::GotoStmtClass:
104   case Stmt::BreakStmtClass:
105   case Stmt::ContinueStmtClass:
106   case Stmt::DefaultStmtClass:
107   case Stmt::CaseStmtClass:
108   case Stmt::SEHLeaveStmtClass:
109     llvm_unreachable("should have emitted these statements as simple");
110 
111 #define STMT(Type, Base)
112 #define ABSTRACT_STMT(Op)
113 #define EXPR(Type, Base) \
114   case Stmt::Type##Class:
115 #include "clang/AST/StmtNodes.inc"
116   {
117     // Remember the block we came in on.
118     llvm::BasicBlock *incoming = Builder.GetInsertBlock();
119     assert(incoming && "expression emission must have an insertion point");
120 
121     EmitIgnoredExpr(cast<Expr>(S));
122 
123     llvm::BasicBlock *outgoing = Builder.GetInsertBlock();
124     assert(outgoing && "expression emission cleared block!");
125 
126     // The expression emitters assume (reasonably!) that the insertion
127     // point is always set.  To maintain that, the call-emission code
128     // for noreturn functions has to enter a new block with no
129     // predecessors.  We want to kill that block and mark the current
130     // insertion point unreachable in the common case of a call like
131     // "exit();".  Since expression emission doesn't otherwise create
132     // blocks with no predecessors, we can just test for that.
133     // However, we must be careful not to do this to our incoming
134     // block, because *statement* emission does sometimes create
135     // reachable blocks which will have no predecessors until later in
136     // the function.  This occurs with, e.g., labels that are not
137     // reachable by fallthrough.
138     if (incoming != outgoing && outgoing->use_empty()) {
139       outgoing->eraseFromParent();
140       Builder.ClearInsertionPoint();
141     }
142     break;
143   }
144 
145   case Stmt::IndirectGotoStmtClass:
146     EmitIndirectGotoStmt(cast<IndirectGotoStmt>(*S)); break;
147 
148   case Stmt::IfStmtClass:      EmitIfStmt(cast<IfStmt>(*S));              break;
149   case Stmt::WhileStmtClass:   EmitWhileStmt(cast<WhileStmt>(*S), Attrs); break;
150   case Stmt::DoStmtClass:      EmitDoStmt(cast<DoStmt>(*S), Attrs);       break;
151   case Stmt::ForStmtClass:     EmitForStmt(cast<ForStmt>(*S), Attrs);     break;
152 
153   case Stmt::ReturnStmtClass:  EmitReturnStmt(cast<ReturnStmt>(*S));      break;
154 
155   case Stmt::SwitchStmtClass:  EmitSwitchStmt(cast<SwitchStmt>(*S));      break;
156   case Stmt::GCCAsmStmtClass:  // Intentional fall-through.
157   case Stmt::MSAsmStmtClass:   EmitAsmStmt(cast<AsmStmt>(*S));            break;
158   case Stmt::CoroutineBodyStmtClass:
159     EmitCoroutineBody(cast<CoroutineBodyStmt>(*S));
160     break;
161   case Stmt::CoreturnStmtClass:
162     EmitCoreturnStmt(cast<CoreturnStmt>(*S));
163     break;
164   case Stmt::CapturedStmtClass: {
165     const CapturedStmt *CS = cast<CapturedStmt>(S);
166     EmitCapturedStmt(*CS, CS->getCapturedRegionKind());
167     }
168     break;
169   case Stmt::ObjCAtTryStmtClass:
170     EmitObjCAtTryStmt(cast<ObjCAtTryStmt>(*S));
171     break;
172   case Stmt::ObjCAtCatchStmtClass:
173     llvm_unreachable(
174                     "@catch statements should be handled by EmitObjCAtTryStmt");
175   case Stmt::ObjCAtFinallyStmtClass:
176     llvm_unreachable(
177                   "@finally statements should be handled by EmitObjCAtTryStmt");
178   case Stmt::ObjCAtThrowStmtClass:
179     EmitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(*S));
180     break;
181   case Stmt::ObjCAtSynchronizedStmtClass:
182     EmitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(*S));
183     break;
184   case Stmt::ObjCForCollectionStmtClass:
185     EmitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(*S));
186     break;
187   case Stmt::ObjCAutoreleasePoolStmtClass:
188     EmitObjCAutoreleasePoolStmt(cast<ObjCAutoreleasePoolStmt>(*S));
189     break;
190 
191   case Stmt::CXXTryStmtClass:
192     EmitCXXTryStmt(cast<CXXTryStmt>(*S));
193     break;
194   case Stmt::CXXForRangeStmtClass:
195     EmitCXXForRangeStmt(cast<CXXForRangeStmt>(*S), Attrs);
196     break;
197   case Stmt::SEHTryStmtClass:
198     EmitSEHTryStmt(cast<SEHTryStmt>(*S));
199     break;
200   case Stmt::OMPMetaDirectiveClass:
201     EmitOMPMetaDirective(cast<OMPMetaDirective>(*S));
202     break;
203   case Stmt::OMPCanonicalLoopClass:
204     EmitOMPCanonicalLoop(cast<OMPCanonicalLoop>(S));
205     break;
206   case Stmt::OMPParallelDirectiveClass:
207     EmitOMPParallelDirective(cast<OMPParallelDirective>(*S));
208     break;
209   case Stmt::OMPSimdDirectiveClass:
210     EmitOMPSimdDirective(cast<OMPSimdDirective>(*S));
211     break;
212   case Stmt::OMPTileDirectiveClass:
213     EmitOMPTileDirective(cast<OMPTileDirective>(*S));
214     break;
215   case Stmt::OMPUnrollDirectiveClass:
216     EmitOMPUnrollDirective(cast<OMPUnrollDirective>(*S));
217     break;
218   case Stmt::OMPForDirectiveClass:
219     EmitOMPForDirective(cast<OMPForDirective>(*S));
220     break;
221   case Stmt::OMPForSimdDirectiveClass:
222     EmitOMPForSimdDirective(cast<OMPForSimdDirective>(*S));
223     break;
224   case Stmt::OMPSectionsDirectiveClass:
225     EmitOMPSectionsDirective(cast<OMPSectionsDirective>(*S));
226     break;
227   case Stmt::OMPSectionDirectiveClass:
228     EmitOMPSectionDirective(cast<OMPSectionDirective>(*S));
229     break;
230   case Stmt::OMPSingleDirectiveClass:
231     EmitOMPSingleDirective(cast<OMPSingleDirective>(*S));
232     break;
233   case Stmt::OMPMasterDirectiveClass:
234     EmitOMPMasterDirective(cast<OMPMasterDirective>(*S));
235     break;
236   case Stmt::OMPCriticalDirectiveClass:
237     EmitOMPCriticalDirective(cast<OMPCriticalDirective>(*S));
238     break;
239   case Stmt::OMPParallelForDirectiveClass:
240     EmitOMPParallelForDirective(cast<OMPParallelForDirective>(*S));
241     break;
242   case Stmt::OMPParallelForSimdDirectiveClass:
243     EmitOMPParallelForSimdDirective(cast<OMPParallelForSimdDirective>(*S));
244     break;
245   case Stmt::OMPParallelMasterDirectiveClass:
246     EmitOMPParallelMasterDirective(cast<OMPParallelMasterDirective>(*S));
247     break;
248   case Stmt::OMPParallelSectionsDirectiveClass:
249     EmitOMPParallelSectionsDirective(cast<OMPParallelSectionsDirective>(*S));
250     break;
251   case Stmt::OMPTaskDirectiveClass:
252     EmitOMPTaskDirective(cast<OMPTaskDirective>(*S));
253     break;
254   case Stmt::OMPTaskyieldDirectiveClass:
255     EmitOMPTaskyieldDirective(cast<OMPTaskyieldDirective>(*S));
256     break;
257   case Stmt::OMPBarrierDirectiveClass:
258     EmitOMPBarrierDirective(cast<OMPBarrierDirective>(*S));
259     break;
260   case Stmt::OMPTaskwaitDirectiveClass:
261     EmitOMPTaskwaitDirective(cast<OMPTaskwaitDirective>(*S));
262     break;
263   case Stmt::OMPTaskgroupDirectiveClass:
264     EmitOMPTaskgroupDirective(cast<OMPTaskgroupDirective>(*S));
265     break;
266   case Stmt::OMPFlushDirectiveClass:
267     EmitOMPFlushDirective(cast<OMPFlushDirective>(*S));
268     break;
269   case Stmt::OMPDepobjDirectiveClass:
270     EmitOMPDepobjDirective(cast<OMPDepobjDirective>(*S));
271     break;
272   case Stmt::OMPScanDirectiveClass:
273     EmitOMPScanDirective(cast<OMPScanDirective>(*S));
274     break;
275   case Stmt::OMPOrderedDirectiveClass:
276     EmitOMPOrderedDirective(cast<OMPOrderedDirective>(*S));
277     break;
278   case Stmt::OMPAtomicDirectiveClass:
279     EmitOMPAtomicDirective(cast<OMPAtomicDirective>(*S));
280     break;
281   case Stmt::OMPTargetDirectiveClass:
282     EmitOMPTargetDirective(cast<OMPTargetDirective>(*S));
283     break;
284   case Stmt::OMPTeamsDirectiveClass:
285     EmitOMPTeamsDirective(cast<OMPTeamsDirective>(*S));
286     break;
287   case Stmt::OMPCancellationPointDirectiveClass:
288     EmitOMPCancellationPointDirective(cast<OMPCancellationPointDirective>(*S));
289     break;
290   case Stmt::OMPCancelDirectiveClass:
291     EmitOMPCancelDirective(cast<OMPCancelDirective>(*S));
292     break;
293   case Stmt::OMPTargetDataDirectiveClass:
294     EmitOMPTargetDataDirective(cast<OMPTargetDataDirective>(*S));
295     break;
296   case Stmt::OMPTargetEnterDataDirectiveClass:
297     EmitOMPTargetEnterDataDirective(cast<OMPTargetEnterDataDirective>(*S));
298     break;
299   case Stmt::OMPTargetExitDataDirectiveClass:
300     EmitOMPTargetExitDataDirective(cast<OMPTargetExitDataDirective>(*S));
301     break;
302   case Stmt::OMPTargetParallelDirectiveClass:
303     EmitOMPTargetParallelDirective(cast<OMPTargetParallelDirective>(*S));
304     break;
305   case Stmt::OMPTargetParallelForDirectiveClass:
306     EmitOMPTargetParallelForDirective(cast<OMPTargetParallelForDirective>(*S));
307     break;
308   case Stmt::OMPTaskLoopDirectiveClass:
309     EmitOMPTaskLoopDirective(cast<OMPTaskLoopDirective>(*S));
310     break;
311   case Stmt::OMPTaskLoopSimdDirectiveClass:
312     EmitOMPTaskLoopSimdDirective(cast<OMPTaskLoopSimdDirective>(*S));
313     break;
314   case Stmt::OMPMasterTaskLoopDirectiveClass:
315     EmitOMPMasterTaskLoopDirective(cast<OMPMasterTaskLoopDirective>(*S));
316     break;
317   case Stmt::OMPMasterTaskLoopSimdDirectiveClass:
318     EmitOMPMasterTaskLoopSimdDirective(
319         cast<OMPMasterTaskLoopSimdDirective>(*S));
320     break;
321   case Stmt::OMPParallelMasterTaskLoopDirectiveClass:
322     EmitOMPParallelMasterTaskLoopDirective(
323         cast<OMPParallelMasterTaskLoopDirective>(*S));
324     break;
325   case Stmt::OMPParallelMasterTaskLoopSimdDirectiveClass:
326     EmitOMPParallelMasterTaskLoopSimdDirective(
327         cast<OMPParallelMasterTaskLoopSimdDirective>(*S));
328     break;
329   case Stmt::OMPDistributeDirectiveClass:
330     EmitOMPDistributeDirective(cast<OMPDistributeDirective>(*S));
331     break;
332   case Stmt::OMPTargetUpdateDirectiveClass:
333     EmitOMPTargetUpdateDirective(cast<OMPTargetUpdateDirective>(*S));
334     break;
335   case Stmt::OMPDistributeParallelForDirectiveClass:
336     EmitOMPDistributeParallelForDirective(
337         cast<OMPDistributeParallelForDirective>(*S));
338     break;
339   case Stmt::OMPDistributeParallelForSimdDirectiveClass:
340     EmitOMPDistributeParallelForSimdDirective(
341         cast<OMPDistributeParallelForSimdDirective>(*S));
342     break;
343   case Stmt::OMPDistributeSimdDirectiveClass:
344     EmitOMPDistributeSimdDirective(cast<OMPDistributeSimdDirective>(*S));
345     break;
346   case Stmt::OMPTargetParallelForSimdDirectiveClass:
347     EmitOMPTargetParallelForSimdDirective(
348         cast<OMPTargetParallelForSimdDirective>(*S));
349     break;
350   case Stmt::OMPTargetSimdDirectiveClass:
351     EmitOMPTargetSimdDirective(cast<OMPTargetSimdDirective>(*S));
352     break;
353   case Stmt::OMPTeamsDistributeDirectiveClass:
354     EmitOMPTeamsDistributeDirective(cast<OMPTeamsDistributeDirective>(*S));
355     break;
356   case Stmt::OMPTeamsDistributeSimdDirectiveClass:
357     EmitOMPTeamsDistributeSimdDirective(
358         cast<OMPTeamsDistributeSimdDirective>(*S));
359     break;
360   case Stmt::OMPTeamsDistributeParallelForSimdDirectiveClass:
361     EmitOMPTeamsDistributeParallelForSimdDirective(
362         cast<OMPTeamsDistributeParallelForSimdDirective>(*S));
363     break;
364   case Stmt::OMPTeamsDistributeParallelForDirectiveClass:
365     EmitOMPTeamsDistributeParallelForDirective(
366         cast<OMPTeamsDistributeParallelForDirective>(*S));
367     break;
368   case Stmt::OMPTargetTeamsDirectiveClass:
369     EmitOMPTargetTeamsDirective(cast<OMPTargetTeamsDirective>(*S));
370     break;
371   case Stmt::OMPTargetTeamsDistributeDirectiveClass:
372     EmitOMPTargetTeamsDistributeDirective(
373         cast<OMPTargetTeamsDistributeDirective>(*S));
374     break;
375   case Stmt::OMPTargetTeamsDistributeParallelForDirectiveClass:
376     EmitOMPTargetTeamsDistributeParallelForDirective(
377         cast<OMPTargetTeamsDistributeParallelForDirective>(*S));
378     break;
379   case Stmt::OMPTargetTeamsDistributeParallelForSimdDirectiveClass:
380     EmitOMPTargetTeamsDistributeParallelForSimdDirective(
381         cast<OMPTargetTeamsDistributeParallelForSimdDirective>(*S));
382     break;
383   case Stmt::OMPTargetTeamsDistributeSimdDirectiveClass:
384     EmitOMPTargetTeamsDistributeSimdDirective(
385         cast<OMPTargetTeamsDistributeSimdDirective>(*S));
386     break;
387   case Stmt::OMPInteropDirectiveClass:
388     llvm_unreachable("Interop directive not supported yet.");
389     break;
390   case Stmt::OMPDispatchDirectiveClass:
391     llvm_unreachable("Dispatch directive not supported yet.");
392     break;
393   case Stmt::OMPMaskedDirectiveClass:
394     EmitOMPMaskedDirective(cast<OMPMaskedDirective>(*S));
395     break;
396   }
397 }
398 
EmitSimpleStmt(const Stmt * S,ArrayRef<const Attr * > Attrs)399 bool CodeGenFunction::EmitSimpleStmt(const Stmt *S,
400                                      ArrayRef<const Attr *> Attrs) {
401   switch (S->getStmtClass()) {
402   default:
403     return false;
404   case Stmt::NullStmtClass:
405     break;
406   case Stmt::CompoundStmtClass:
407     EmitCompoundStmt(cast<CompoundStmt>(*S));
408     break;
409   case Stmt::DeclStmtClass:
410     EmitDeclStmt(cast<DeclStmt>(*S));
411     break;
412   case Stmt::LabelStmtClass:
413     EmitLabelStmt(cast<LabelStmt>(*S));
414     break;
415   case Stmt::AttributedStmtClass:
416     EmitAttributedStmt(cast<AttributedStmt>(*S));
417     break;
418   case Stmt::GotoStmtClass:
419     EmitGotoStmt(cast<GotoStmt>(*S));
420     break;
421   case Stmt::BreakStmtClass:
422     EmitBreakStmt(cast<BreakStmt>(*S));
423     break;
424   case Stmt::ContinueStmtClass:
425     EmitContinueStmt(cast<ContinueStmt>(*S));
426     break;
427   case Stmt::DefaultStmtClass:
428     EmitDefaultStmt(cast<DefaultStmt>(*S), Attrs);
429     break;
430   case Stmt::CaseStmtClass:
431     EmitCaseStmt(cast<CaseStmt>(*S), Attrs);
432     break;
433   case Stmt::SEHLeaveStmtClass:
434     EmitSEHLeaveStmt(cast<SEHLeaveStmt>(*S));
435     break;
436   }
437   return true;
438 }
439 
440 /// EmitCompoundStmt - Emit a compound statement {..} node.  If GetLast is true,
441 /// this captures the expression result of the last sub-statement and returns it
442 /// (for use by the statement expression extension).
EmitCompoundStmt(const CompoundStmt & S,bool GetLast,AggValueSlot AggSlot)443 Address CodeGenFunction::EmitCompoundStmt(const CompoundStmt &S, bool GetLast,
444                                           AggValueSlot AggSlot) {
445   PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),S.getLBracLoc(),
446                              "LLVM IR generation of compound statement ('{}')");
447 
448   // Keep track of the current cleanup stack depth, including debug scopes.
449   LexicalScope Scope(*this, S.getSourceRange());
450 
451   return EmitCompoundStmtWithoutScope(S, GetLast, AggSlot);
452 }
453 
454 Address
EmitCompoundStmtWithoutScope(const CompoundStmt & S,bool GetLast,AggValueSlot AggSlot)455 CodeGenFunction::EmitCompoundStmtWithoutScope(const CompoundStmt &S,
456                                               bool GetLast,
457                                               AggValueSlot AggSlot) {
458 
459   const Stmt *ExprResult = S.getStmtExprResult();
460   assert((!GetLast || (GetLast && ExprResult)) &&
461          "If GetLast is true then the CompoundStmt must have a StmtExprResult");
462 
463   Address RetAlloca = Address::invalid();
464 
465   for (auto *CurStmt : S.body()) {
466     if (GetLast && ExprResult == CurStmt) {
467       // We have to special case labels here.  They are statements, but when put
468       // at the end of a statement expression, they yield the value of their
469       // subexpression.  Handle this by walking through all labels we encounter,
470       // emitting them before we evaluate the subexpr.
471       // Similar issues arise for attributed statements.
472       while (!isa<Expr>(ExprResult)) {
473         if (const auto *LS = dyn_cast<LabelStmt>(ExprResult)) {
474           EmitLabel(LS->getDecl());
475           ExprResult = LS->getSubStmt();
476         } else if (const auto *AS = dyn_cast<AttributedStmt>(ExprResult)) {
477           // FIXME: Update this if we ever have attributes that affect the
478           // semantics of an expression.
479           ExprResult = AS->getSubStmt();
480         } else {
481           llvm_unreachable("unknown value statement");
482         }
483       }
484 
485       EnsureInsertPoint();
486 
487       const Expr *E = cast<Expr>(ExprResult);
488       QualType ExprTy = E->getType();
489       if (hasAggregateEvaluationKind(ExprTy)) {
490         EmitAggExpr(E, AggSlot);
491       } else {
492         // We can't return an RValue here because there might be cleanups at
493         // the end of the StmtExpr.  Because of that, we have to emit the result
494         // here into a temporary alloca.
495         RetAlloca = CreateMemTemp(ExprTy);
496         EmitAnyExprToMem(E, RetAlloca, Qualifiers(),
497                          /*IsInit*/ false);
498       }
499     } else {
500       EmitStmt(CurStmt);
501     }
502   }
503 
504   return RetAlloca;
505 }
506 
SimplifyForwardingBlocks(llvm::BasicBlock * BB)507 void CodeGenFunction::SimplifyForwardingBlocks(llvm::BasicBlock *BB) {
508   llvm::BranchInst *BI = dyn_cast<llvm::BranchInst>(BB->getTerminator());
509 
510   // If there is a cleanup stack, then we it isn't worth trying to
511   // simplify this block (we would need to remove it from the scope map
512   // and cleanup entry).
513   if (!EHStack.empty())
514     return;
515 
516   // Can only simplify direct branches.
517   if (!BI || !BI->isUnconditional())
518     return;
519 
520   // Can only simplify empty blocks.
521   if (BI->getIterator() != BB->begin())
522     return;
523 
524   BB->replaceAllUsesWith(BI->getSuccessor(0));
525   BI->eraseFromParent();
526   BB->eraseFromParent();
527 }
528 
EmitBlock(llvm::BasicBlock * BB,bool IsFinished)529 void CodeGenFunction::EmitBlock(llvm::BasicBlock *BB, bool IsFinished) {
530   llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
531 
532   // Fall out of the current block (if necessary).
533   EmitBranch(BB);
534 
535   if (IsFinished && BB->use_empty()) {
536     delete BB;
537     return;
538   }
539 
540   // Place the block after the current block, if possible, or else at
541   // the end of the function.
542   if (CurBB && CurBB->getParent())
543     CurFn->getBasicBlockList().insertAfter(CurBB->getIterator(), BB);
544   else
545     CurFn->getBasicBlockList().push_back(BB);
546   Builder.SetInsertPoint(BB);
547 }
548 
EmitBranch(llvm::BasicBlock * Target)549 void CodeGenFunction::EmitBranch(llvm::BasicBlock *Target) {
550   // Emit a branch from the current block to the target one if this
551   // was a real block.  If this was just a fall-through block after a
552   // terminator, don't emit it.
553   llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
554 
555   if (!CurBB || CurBB->getTerminator()) {
556     // If there is no insert point or the previous block is already
557     // terminated, don't touch it.
558   } else {
559     // Otherwise, create a fall-through branch.
560     Builder.CreateBr(Target);
561   }
562 
563   Builder.ClearInsertionPoint();
564 }
565 
EmitBlockAfterUses(llvm::BasicBlock * block)566 void CodeGenFunction::EmitBlockAfterUses(llvm::BasicBlock *block) {
567   bool inserted = false;
568   for (llvm::User *u : block->users()) {
569     if (llvm::Instruction *insn = dyn_cast<llvm::Instruction>(u)) {
570       CurFn->getBasicBlockList().insertAfter(insn->getParent()->getIterator(),
571                                              block);
572       inserted = true;
573       break;
574     }
575   }
576 
577   if (!inserted)
578     CurFn->getBasicBlockList().push_back(block);
579 
580   Builder.SetInsertPoint(block);
581 }
582 
583 CodeGenFunction::JumpDest
getJumpDestForLabel(const LabelDecl * D)584 CodeGenFunction::getJumpDestForLabel(const LabelDecl *D) {
585   JumpDest &Dest = LabelMap[D];
586   if (Dest.isValid()) return Dest;
587 
588   // Create, but don't insert, the new block.
589   Dest = JumpDest(createBasicBlock(D->getName()),
590                   EHScopeStack::stable_iterator::invalid(),
591                   NextCleanupDestIndex++);
592   return Dest;
593 }
594 
EmitLabel(const LabelDecl * D)595 void CodeGenFunction::EmitLabel(const LabelDecl *D) {
596   // Add this label to the current lexical scope if we're within any
597   // normal cleanups.  Jumps "in" to this label --- when permitted by
598   // the language --- may need to be routed around such cleanups.
599   if (EHStack.hasNormalCleanups() && CurLexicalScope)
600     CurLexicalScope->addLabel(D);
601 
602   JumpDest &Dest = LabelMap[D];
603 
604   // If we didn't need a forward reference to this label, just go
605   // ahead and create a destination at the current scope.
606   if (!Dest.isValid()) {
607     Dest = getJumpDestInCurrentScope(D->getName());
608 
609   // Otherwise, we need to give this label a target depth and remove
610   // it from the branch-fixups list.
611   } else {
612     assert(!Dest.getScopeDepth().isValid() && "already emitted label!");
613     Dest.setScopeDepth(EHStack.stable_begin());
614     ResolveBranchFixups(Dest.getBlock());
615   }
616 
617   EmitBlock(Dest.getBlock());
618 
619   // Emit debug info for labels.
620   if (CGDebugInfo *DI = getDebugInfo()) {
621     if (CGM.getCodeGenOpts().hasReducedDebugInfo()) {
622       DI->setLocation(D->getLocation());
623       DI->EmitLabel(D, Builder);
624     }
625   }
626 
627   incrementProfileCounter(D->getStmt());
628 }
629 
630 /// Change the cleanup scope of the labels in this lexical scope to
631 /// match the scope of the enclosing context.
rescopeLabels()632 void CodeGenFunction::LexicalScope::rescopeLabels() {
633   assert(!Labels.empty());
634   EHScopeStack::stable_iterator innermostScope
635     = CGF.EHStack.getInnermostNormalCleanup();
636 
637   // Change the scope depth of all the labels.
638   for (SmallVectorImpl<const LabelDecl*>::const_iterator
639          i = Labels.begin(), e = Labels.end(); i != e; ++i) {
640     assert(CGF.LabelMap.count(*i));
641     JumpDest &dest = CGF.LabelMap.find(*i)->second;
642     assert(dest.getScopeDepth().isValid());
643     assert(innermostScope.encloses(dest.getScopeDepth()));
644     dest.setScopeDepth(innermostScope);
645   }
646 
647   // Reparent the labels if the new scope also has cleanups.
648   if (innermostScope != EHScopeStack::stable_end() && ParentScope) {
649     ParentScope->Labels.append(Labels.begin(), Labels.end());
650   }
651 }
652 
653 
EmitLabelStmt(const LabelStmt & S)654 void CodeGenFunction::EmitLabelStmt(const LabelStmt &S) {
655   EmitLabel(S.getDecl());
656 
657   // IsEHa - emit eha.scope.begin if it's a side entry of a scope
658   if (getLangOpts().EHAsynch && S.isSideEntry())
659     EmitSehCppScopeBegin();
660 
661   EmitStmt(S.getSubStmt());
662 }
663 
EmitAttributedStmt(const AttributedStmt & S)664 void CodeGenFunction::EmitAttributedStmt(const AttributedStmt &S) {
665   bool nomerge = false;
666   const CallExpr *musttail = nullptr;
667 
668   for (const auto *A : S.getAttrs()) {
669     if (A->getKind() == attr::NoMerge) {
670       nomerge = true;
671     }
672     if (A->getKind() == attr::MustTail) {
673       const Stmt *Sub = S.getSubStmt();
674       const ReturnStmt *R = cast<ReturnStmt>(Sub);
675       musttail = cast<CallExpr>(R->getRetValue()->IgnoreParens());
676     }
677   }
678   SaveAndRestore<bool> save_nomerge(InNoMergeAttributedStmt, nomerge);
679   SaveAndRestore<const CallExpr *> save_musttail(MustTailCall, musttail);
680   EmitStmt(S.getSubStmt(), S.getAttrs());
681 }
682 
EmitGotoStmt(const GotoStmt & S)683 void CodeGenFunction::EmitGotoStmt(const GotoStmt &S) {
684   // If this code is reachable then emit a stop point (if generating
685   // debug info). We have to do this ourselves because we are on the
686   // "simple" statement path.
687   if (HaveInsertPoint())
688     EmitStopPoint(&S);
689 
690   EmitBranchThroughCleanup(getJumpDestForLabel(S.getLabel()));
691 }
692 
693 
EmitIndirectGotoStmt(const IndirectGotoStmt & S)694 void CodeGenFunction::EmitIndirectGotoStmt(const IndirectGotoStmt &S) {
695   if (const LabelDecl *Target = S.getConstantTarget()) {
696     EmitBranchThroughCleanup(getJumpDestForLabel(Target));
697     return;
698   }
699 
700   // Ensure that we have an i8* for our PHI node.
701   llvm::Value *V = Builder.CreateBitCast(EmitScalarExpr(S.getTarget()),
702                                          Int8PtrTy, "addr");
703   llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
704 
705   // Get the basic block for the indirect goto.
706   llvm::BasicBlock *IndGotoBB = GetIndirectGotoBlock();
707 
708   // The first instruction in the block has to be the PHI for the switch dest,
709   // add an entry for this branch.
710   cast<llvm::PHINode>(IndGotoBB->begin())->addIncoming(V, CurBB);
711 
712   EmitBranch(IndGotoBB);
713 }
714 
EmitIfStmt(const IfStmt & S)715 void CodeGenFunction::EmitIfStmt(const IfStmt &S) {
716   // The else branch of a consteval if statement is always the only branch that
717   // can be runtime evaluated.
718   if (S.isConsteval()) {
719     const Stmt *Executed = S.isNegatedConsteval() ? S.getThen() : S.getElse();
720     if (Executed) {
721       RunCleanupsScope ExecutedScope(*this);
722       EmitStmt(Executed);
723     }
724     return;
725   }
726 
727   // C99 6.8.4.1: The first substatement is executed if the expression compares
728   // unequal to 0.  The condition must be a scalar type.
729   LexicalScope ConditionScope(*this, S.getCond()->getSourceRange());
730 
731   if (S.getInit())
732     EmitStmt(S.getInit());
733 
734   if (S.getConditionVariable())
735     EmitDecl(*S.getConditionVariable());
736 
737   // If the condition constant folds and can be elided, try to avoid emitting
738   // the condition and the dead arm of the if/else.
739   bool CondConstant;
740   if (ConstantFoldsToSimpleInteger(S.getCond(), CondConstant,
741                                    S.isConstexpr())) {
742     // Figure out which block (then or else) is executed.
743     const Stmt *Executed = S.getThen();
744     const Stmt *Skipped  = S.getElse();
745     if (!CondConstant)  // Condition false?
746       std::swap(Executed, Skipped);
747 
748     // If the skipped block has no labels in it, just emit the executed block.
749     // This avoids emitting dead code and simplifies the CFG substantially.
750     if (S.isConstexpr() || !ContainsLabel(Skipped)) {
751       if (CondConstant)
752         incrementProfileCounter(&S);
753       if (Executed) {
754         RunCleanupsScope ExecutedScope(*this);
755         EmitStmt(Executed);
756       }
757       return;
758     }
759   }
760 
761   // Otherwise, the condition did not fold, or we couldn't elide it.  Just emit
762   // the conditional branch.
763   llvm::BasicBlock *ThenBlock = createBasicBlock("if.then");
764   llvm::BasicBlock *ContBlock = createBasicBlock("if.end");
765   llvm::BasicBlock *ElseBlock = ContBlock;
766   if (S.getElse())
767     ElseBlock = createBasicBlock("if.else");
768 
769   // Prefer the PGO based weights over the likelihood attribute.
770   // When the build isn't optimized the metadata isn't used, so don't generate
771   // it.
772   Stmt::Likelihood LH = Stmt::LH_None;
773   uint64_t Count = getProfileCount(S.getThen());
774   if (!Count && CGM.getCodeGenOpts().OptimizationLevel)
775     LH = Stmt::getLikelihood(S.getThen(), S.getElse());
776   EmitBranchOnBoolExpr(S.getCond(), ThenBlock, ElseBlock, Count, LH);
777 
778   // Emit the 'then' code.
779   EmitBlock(ThenBlock);
780   incrementProfileCounter(&S);
781   {
782     RunCleanupsScope ThenScope(*this);
783     EmitStmt(S.getThen());
784   }
785   EmitBranch(ContBlock);
786 
787   // Emit the 'else' code if present.
788   if (const Stmt *Else = S.getElse()) {
789     {
790       // There is no need to emit line number for an unconditional branch.
791       auto NL = ApplyDebugLocation::CreateEmpty(*this);
792       EmitBlock(ElseBlock);
793     }
794     {
795       RunCleanupsScope ElseScope(*this);
796       EmitStmt(Else);
797     }
798     {
799       // There is no need to emit line number for an unconditional branch.
800       auto NL = ApplyDebugLocation::CreateEmpty(*this);
801       EmitBranch(ContBlock);
802     }
803   }
804 
805   // Emit the continuation block for code after the if.
806   EmitBlock(ContBlock, true);
807 }
808 
EmitWhileStmt(const WhileStmt & S,ArrayRef<const Attr * > WhileAttrs)809 void CodeGenFunction::EmitWhileStmt(const WhileStmt &S,
810                                     ArrayRef<const Attr *> WhileAttrs) {
811   // Emit the header for the loop, which will also become
812   // the continue target.
813   JumpDest LoopHeader = getJumpDestInCurrentScope("while.cond");
814   EmitBlock(LoopHeader.getBlock());
815 
816   // Create an exit block for when the condition fails, which will
817   // also become the break target.
818   JumpDest LoopExit = getJumpDestInCurrentScope("while.end");
819 
820   // Store the blocks to use for break and continue.
821   BreakContinueStack.push_back(BreakContinue(LoopExit, LoopHeader));
822 
823   // C++ [stmt.while]p2:
824   //   When the condition of a while statement is a declaration, the
825   //   scope of the variable that is declared extends from its point
826   //   of declaration (3.3.2) to the end of the while statement.
827   //   [...]
828   //   The object created in a condition is destroyed and created
829   //   with each iteration of the loop.
830   RunCleanupsScope ConditionScope(*this);
831 
832   if (S.getConditionVariable())
833     EmitDecl(*S.getConditionVariable());
834 
835   // Evaluate the conditional in the while header.  C99 6.8.5.1: The
836   // evaluation of the controlling expression takes place before each
837   // execution of the loop body.
838   llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
839 
840   // while(1) is common, avoid extra exit blocks.  Be sure
841   // to correctly handle break/continue though.
842   llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal);
843   bool CondIsConstInt = C != nullptr;
844   bool EmitBoolCondBranch = !CondIsConstInt || !C->isOne();
845   const SourceRange &R = S.getSourceRange();
846   LoopStack.push(LoopHeader.getBlock(), CGM.getContext(), CGM.getCodeGenOpts(),
847                  WhileAttrs, SourceLocToDebugLoc(R.getBegin()),
848                  SourceLocToDebugLoc(R.getEnd()),
849                  checkIfLoopMustProgress(CondIsConstInt));
850 
851   // As long as the condition is true, go to the loop body.
852   llvm::BasicBlock *LoopBody = createBasicBlock("while.body");
853   if (EmitBoolCondBranch) {
854     llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
855     if (ConditionScope.requiresCleanups())
856       ExitBlock = createBasicBlock("while.exit");
857     llvm::MDNode *Weights =
858         createProfileWeightsForLoop(S.getCond(), getProfileCount(S.getBody()));
859     if (!Weights && CGM.getCodeGenOpts().OptimizationLevel)
860       BoolCondVal = emitCondLikelihoodViaExpectIntrinsic(
861           BoolCondVal, Stmt::getLikelihood(S.getBody()));
862     Builder.CreateCondBr(BoolCondVal, LoopBody, ExitBlock, Weights);
863 
864     if (ExitBlock != LoopExit.getBlock()) {
865       EmitBlock(ExitBlock);
866       EmitBranchThroughCleanup(LoopExit);
867     }
868   } else if (const Attr *A = Stmt::getLikelihoodAttr(S.getBody())) {
869     CGM.getDiags().Report(A->getLocation(),
870                           diag::warn_attribute_has_no_effect_on_infinite_loop)
871         << A << A->getRange();
872     CGM.getDiags().Report(
873         S.getWhileLoc(),
874         diag::note_attribute_has_no_effect_on_infinite_loop_here)
875         << SourceRange(S.getWhileLoc(), S.getRParenLoc());
876   }
877 
878   // Emit the loop body.  We have to emit this in a cleanup scope
879   // because it might be a singleton DeclStmt.
880   {
881     RunCleanupsScope BodyScope(*this);
882     EmitBlock(LoopBody);
883     incrementProfileCounter(&S);
884     EmitStmt(S.getBody());
885   }
886 
887   BreakContinueStack.pop_back();
888 
889   // Immediately force cleanup.
890   ConditionScope.ForceCleanup();
891 
892   EmitStopPoint(&S);
893   // Branch to the loop header again.
894   EmitBranch(LoopHeader.getBlock());
895 
896   LoopStack.pop();
897 
898   // Emit the exit block.
899   EmitBlock(LoopExit.getBlock(), true);
900 
901   // The LoopHeader typically is just a branch if we skipped emitting
902   // a branch, try to erase it.
903   if (!EmitBoolCondBranch)
904     SimplifyForwardingBlocks(LoopHeader.getBlock());
905 }
906 
EmitDoStmt(const DoStmt & S,ArrayRef<const Attr * > DoAttrs)907 void CodeGenFunction::EmitDoStmt(const DoStmt &S,
908                                  ArrayRef<const Attr *> DoAttrs) {
909   JumpDest LoopExit = getJumpDestInCurrentScope("do.end");
910   JumpDest LoopCond = getJumpDestInCurrentScope("do.cond");
911 
912   uint64_t ParentCount = getCurrentProfileCount();
913 
914   // Store the blocks to use for break and continue.
915   BreakContinueStack.push_back(BreakContinue(LoopExit, LoopCond));
916 
917   // Emit the body of the loop.
918   llvm::BasicBlock *LoopBody = createBasicBlock("do.body");
919 
920   EmitBlockWithFallThrough(LoopBody, &S);
921   {
922     RunCleanupsScope BodyScope(*this);
923     EmitStmt(S.getBody());
924   }
925 
926   EmitBlock(LoopCond.getBlock());
927 
928   // C99 6.8.5.2: "The evaluation of the controlling expression takes place
929   // after each execution of the loop body."
930 
931   // Evaluate the conditional in the while header.
932   // C99 6.8.5p2/p4: The first substatement is executed if the expression
933   // compares unequal to 0.  The condition must be a scalar type.
934   llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
935 
936   BreakContinueStack.pop_back();
937 
938   // "do {} while (0)" is common in macros, avoid extra blocks.  Be sure
939   // to correctly handle break/continue though.
940   llvm::ConstantInt *C = dyn_cast<llvm::ConstantInt>(BoolCondVal);
941   bool CondIsConstInt = C;
942   bool EmitBoolCondBranch = !C || !C->isZero();
943 
944   const SourceRange &R = S.getSourceRange();
945   LoopStack.push(LoopBody, CGM.getContext(), CGM.getCodeGenOpts(), DoAttrs,
946                  SourceLocToDebugLoc(R.getBegin()),
947                  SourceLocToDebugLoc(R.getEnd()),
948                  checkIfLoopMustProgress(CondIsConstInt));
949 
950   // As long as the condition is true, iterate the loop.
951   if (EmitBoolCondBranch) {
952     uint64_t BackedgeCount = getProfileCount(S.getBody()) - ParentCount;
953     Builder.CreateCondBr(
954         BoolCondVal, LoopBody, LoopExit.getBlock(),
955         createProfileWeightsForLoop(S.getCond(), BackedgeCount));
956   }
957 
958   LoopStack.pop();
959 
960   // Emit the exit block.
961   EmitBlock(LoopExit.getBlock());
962 
963   // The DoCond block typically is just a branch if we skipped
964   // emitting a branch, try to erase it.
965   if (!EmitBoolCondBranch)
966     SimplifyForwardingBlocks(LoopCond.getBlock());
967 }
968 
EmitForStmt(const ForStmt & S,ArrayRef<const Attr * > ForAttrs)969 void CodeGenFunction::EmitForStmt(const ForStmt &S,
970                                   ArrayRef<const Attr *> ForAttrs) {
971   JumpDest LoopExit = getJumpDestInCurrentScope("for.end");
972 
973   LexicalScope ForScope(*this, S.getSourceRange());
974 
975   // Evaluate the first part before the loop.
976   if (S.getInit())
977     EmitStmt(S.getInit());
978 
979   // Start the loop with a block that tests the condition.
980   // If there's an increment, the continue scope will be overwritten
981   // later.
982   JumpDest CondDest = getJumpDestInCurrentScope("for.cond");
983   llvm::BasicBlock *CondBlock = CondDest.getBlock();
984   EmitBlock(CondBlock);
985 
986   Expr::EvalResult Result;
987   bool CondIsConstInt =
988       !S.getCond() || S.getCond()->EvaluateAsInt(Result, getContext());
989 
990   const SourceRange &R = S.getSourceRange();
991   LoopStack.push(CondBlock, CGM.getContext(), CGM.getCodeGenOpts(), ForAttrs,
992                  SourceLocToDebugLoc(R.getBegin()),
993                  SourceLocToDebugLoc(R.getEnd()),
994                  checkIfLoopMustProgress(CondIsConstInt));
995 
996   // Create a cleanup scope for the condition variable cleanups.
997   LexicalScope ConditionScope(*this, S.getSourceRange());
998 
999   // If the for loop doesn't have an increment we can just use the condition as
1000   // the continue block. Otherwise, if there is no condition variable, we can
1001   // form the continue block now. If there is a condition variable, we can't
1002   // form the continue block until after we've emitted the condition, because
1003   // the condition is in scope in the increment, but Sema's jump diagnostics
1004   // ensure that there are no continues from the condition variable that jump
1005   // to the loop increment.
1006   JumpDest Continue;
1007   if (!S.getInc())
1008     Continue = CondDest;
1009   else if (!S.getConditionVariable())
1010     Continue = getJumpDestInCurrentScope("for.inc");
1011   BreakContinueStack.push_back(BreakContinue(LoopExit, Continue));
1012 
1013   if (S.getCond()) {
1014     // If the for statement has a condition scope, emit the local variable
1015     // declaration.
1016     if (S.getConditionVariable()) {
1017       EmitDecl(*S.getConditionVariable());
1018 
1019       // We have entered the condition variable's scope, so we're now able to
1020       // jump to the continue block.
1021       Continue = S.getInc() ? getJumpDestInCurrentScope("for.inc") : CondDest;
1022       BreakContinueStack.back().ContinueBlock = Continue;
1023     }
1024 
1025     llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
1026     // If there are any cleanups between here and the loop-exit scope,
1027     // create a block to stage a loop exit along.
1028     if (ForScope.requiresCleanups())
1029       ExitBlock = createBasicBlock("for.cond.cleanup");
1030 
1031     // As long as the condition is true, iterate the loop.
1032     llvm::BasicBlock *ForBody = createBasicBlock("for.body");
1033 
1034     // C99 6.8.5p2/p4: The first substatement is executed if the expression
1035     // compares unequal to 0.  The condition must be a scalar type.
1036     llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
1037     llvm::MDNode *Weights =
1038         createProfileWeightsForLoop(S.getCond(), getProfileCount(S.getBody()));
1039     if (!Weights && CGM.getCodeGenOpts().OptimizationLevel)
1040       BoolCondVal = emitCondLikelihoodViaExpectIntrinsic(
1041           BoolCondVal, Stmt::getLikelihood(S.getBody()));
1042 
1043     Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock, Weights);
1044 
1045     if (ExitBlock != LoopExit.getBlock()) {
1046       EmitBlock(ExitBlock);
1047       EmitBranchThroughCleanup(LoopExit);
1048     }
1049 
1050     EmitBlock(ForBody);
1051   } else {
1052     // Treat it as a non-zero constant.  Don't even create a new block for the
1053     // body, just fall into it.
1054   }
1055   incrementProfileCounter(&S);
1056 
1057   {
1058     // Create a separate cleanup scope for the body, in case it is not
1059     // a compound statement.
1060     RunCleanupsScope BodyScope(*this);
1061     EmitStmt(S.getBody());
1062   }
1063 
1064   // If there is an increment, emit it next.
1065   if (S.getInc()) {
1066     EmitBlock(Continue.getBlock());
1067     EmitStmt(S.getInc());
1068   }
1069 
1070   BreakContinueStack.pop_back();
1071 
1072   ConditionScope.ForceCleanup();
1073 
1074   EmitStopPoint(&S);
1075   EmitBranch(CondBlock);
1076 
1077   ForScope.ForceCleanup();
1078 
1079   LoopStack.pop();
1080 
1081   // Emit the fall-through block.
1082   EmitBlock(LoopExit.getBlock(), true);
1083 }
1084 
1085 void
EmitCXXForRangeStmt(const CXXForRangeStmt & S,ArrayRef<const Attr * > ForAttrs)1086 CodeGenFunction::EmitCXXForRangeStmt(const CXXForRangeStmt &S,
1087                                      ArrayRef<const Attr *> ForAttrs) {
1088   JumpDest LoopExit = getJumpDestInCurrentScope("for.end");
1089 
1090   LexicalScope ForScope(*this, S.getSourceRange());
1091 
1092   // Evaluate the first pieces before the loop.
1093   if (S.getInit())
1094     EmitStmt(S.getInit());
1095   EmitStmt(S.getRangeStmt());
1096   EmitStmt(S.getBeginStmt());
1097   EmitStmt(S.getEndStmt());
1098 
1099   // Start the loop with a block that tests the condition.
1100   // If there's an increment, the continue scope will be overwritten
1101   // later.
1102   llvm::BasicBlock *CondBlock = createBasicBlock("for.cond");
1103   EmitBlock(CondBlock);
1104 
1105   const SourceRange &R = S.getSourceRange();
1106   LoopStack.push(CondBlock, CGM.getContext(), CGM.getCodeGenOpts(), ForAttrs,
1107                  SourceLocToDebugLoc(R.getBegin()),
1108                  SourceLocToDebugLoc(R.getEnd()));
1109 
1110   // If there are any cleanups between here and the loop-exit scope,
1111   // create a block to stage a loop exit along.
1112   llvm::BasicBlock *ExitBlock = LoopExit.getBlock();
1113   if (ForScope.requiresCleanups())
1114     ExitBlock = createBasicBlock("for.cond.cleanup");
1115 
1116   // The loop body, consisting of the specified body and the loop variable.
1117   llvm::BasicBlock *ForBody = createBasicBlock("for.body");
1118 
1119   // The body is executed if the expression, contextually converted
1120   // to bool, is true.
1121   llvm::Value *BoolCondVal = EvaluateExprAsBool(S.getCond());
1122   llvm::MDNode *Weights =
1123       createProfileWeightsForLoop(S.getCond(), getProfileCount(S.getBody()));
1124   if (!Weights && CGM.getCodeGenOpts().OptimizationLevel)
1125     BoolCondVal = emitCondLikelihoodViaExpectIntrinsic(
1126         BoolCondVal, Stmt::getLikelihood(S.getBody()));
1127   Builder.CreateCondBr(BoolCondVal, ForBody, ExitBlock, Weights);
1128 
1129   if (ExitBlock != LoopExit.getBlock()) {
1130     EmitBlock(ExitBlock);
1131     EmitBranchThroughCleanup(LoopExit);
1132   }
1133 
1134   EmitBlock(ForBody);
1135   incrementProfileCounter(&S);
1136 
1137   // Create a block for the increment. In case of a 'continue', we jump there.
1138   JumpDest Continue = getJumpDestInCurrentScope("for.inc");
1139 
1140   // Store the blocks to use for break and continue.
1141   BreakContinueStack.push_back(BreakContinue(LoopExit, Continue));
1142 
1143   {
1144     // Create a separate cleanup scope for the loop variable and body.
1145     LexicalScope BodyScope(*this, S.getSourceRange());
1146     EmitStmt(S.getLoopVarStmt());
1147     EmitStmt(S.getBody());
1148   }
1149 
1150   EmitStopPoint(&S);
1151   // If there is an increment, emit it next.
1152   EmitBlock(Continue.getBlock());
1153   EmitStmt(S.getInc());
1154 
1155   BreakContinueStack.pop_back();
1156 
1157   EmitBranch(CondBlock);
1158 
1159   ForScope.ForceCleanup();
1160 
1161   LoopStack.pop();
1162 
1163   // Emit the fall-through block.
1164   EmitBlock(LoopExit.getBlock(), true);
1165 }
1166 
EmitReturnOfRValue(RValue RV,QualType Ty)1167 void CodeGenFunction::EmitReturnOfRValue(RValue RV, QualType Ty) {
1168   if (RV.isScalar()) {
1169     Builder.CreateStore(RV.getScalarVal(), ReturnValue);
1170   } else if (RV.isAggregate()) {
1171     LValue Dest = MakeAddrLValue(ReturnValue, Ty);
1172     LValue Src = MakeAddrLValue(RV.getAggregateAddress(), Ty);
1173     EmitAggregateCopy(Dest, Src, Ty, getOverlapForReturnValue());
1174   } else {
1175     EmitStoreOfComplex(RV.getComplexVal(), MakeAddrLValue(ReturnValue, Ty),
1176                        /*init*/ true);
1177   }
1178   EmitBranchThroughCleanup(ReturnBlock);
1179 }
1180 
1181 namespace {
1182 // RAII struct used to save and restore a return statment's result expression.
1183 struct SaveRetExprRAII {
SaveRetExprRAII__anon8cbcbdc90111::SaveRetExprRAII1184   SaveRetExprRAII(const Expr *RetExpr, CodeGenFunction &CGF)
1185       : OldRetExpr(CGF.RetExpr), CGF(CGF) {
1186     CGF.RetExpr = RetExpr;
1187   }
~SaveRetExprRAII__anon8cbcbdc90111::SaveRetExprRAII1188   ~SaveRetExprRAII() { CGF.RetExpr = OldRetExpr; }
1189   const Expr *OldRetExpr;
1190   CodeGenFunction &CGF;
1191 };
1192 } // namespace
1193 
1194 /// If we have 'return f(...);', where both caller and callee are SwiftAsync,
1195 /// codegen it as 'tail call ...; ret void;'.
makeTailCallIfSwiftAsync(const CallExpr * CE,CGBuilderTy & Builder,const CGFunctionInfo * CurFnInfo)1196 static void makeTailCallIfSwiftAsync(const CallExpr *CE, CGBuilderTy &Builder,
1197                                      const CGFunctionInfo *CurFnInfo) {
1198   auto calleeQualType = CE->getCallee()->getType();
1199   const FunctionType *calleeType = nullptr;
1200   if (calleeQualType->isFunctionPointerType() ||
1201       calleeQualType->isFunctionReferenceType() ||
1202       calleeQualType->isBlockPointerType() ||
1203       calleeQualType->isMemberFunctionPointerType()) {
1204     calleeType = calleeQualType->getPointeeType()->castAs<FunctionType>();
1205   } else if (auto *ty = dyn_cast<FunctionType>(calleeQualType)) {
1206     calleeType = ty;
1207   } else if (auto CMCE = dyn_cast<CXXMemberCallExpr>(CE)) {
1208     if (auto methodDecl = CMCE->getMethodDecl()) {
1209       // getMethodDecl() doesn't handle member pointers at the moment.
1210       calleeType = methodDecl->getType()->castAs<FunctionType>();
1211     } else {
1212       return;
1213     }
1214   } else {
1215     return;
1216   }
1217   if (calleeType->getCallConv() == CallingConv::CC_SwiftAsync &&
1218       (CurFnInfo->getASTCallingConvention() == CallingConv::CC_SwiftAsync)) {
1219     auto CI = cast<llvm::CallInst>(&Builder.GetInsertBlock()->back());
1220     CI->setTailCallKind(llvm::CallInst::TCK_MustTail);
1221     Builder.CreateRetVoid();
1222     Builder.ClearInsertionPoint();
1223   }
1224 }
1225 
1226 /// EmitReturnStmt - Note that due to GCC extensions, this can have an operand
1227 /// if the function returns void, or may be missing one if the function returns
1228 /// non-void.  Fun stuff :).
EmitReturnStmt(const ReturnStmt & S)1229 void CodeGenFunction::EmitReturnStmt(const ReturnStmt &S) {
1230   if (requiresReturnValueCheck()) {
1231     llvm::Constant *SLoc = EmitCheckSourceLocation(S.getBeginLoc());
1232     auto *SLocPtr =
1233         new llvm::GlobalVariable(CGM.getModule(), SLoc->getType(), false,
1234                                  llvm::GlobalVariable::PrivateLinkage, SLoc);
1235     SLocPtr->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
1236     CGM.getSanitizerMetadata()->disableSanitizerForGlobal(SLocPtr);
1237     assert(ReturnLocation.isValid() && "No valid return location");
1238     Builder.CreateStore(Builder.CreateBitCast(SLocPtr, Int8PtrTy),
1239                         ReturnLocation);
1240   }
1241 
1242   // Returning from an outlined SEH helper is UB, and we already warn on it.
1243   if (IsOutlinedSEHHelper) {
1244     Builder.CreateUnreachable();
1245     Builder.ClearInsertionPoint();
1246   }
1247 
1248   // Emit the result value, even if unused, to evaluate the side effects.
1249   const Expr *RV = S.getRetValue();
1250 
1251   // Record the result expression of the return statement. The recorded
1252   // expression is used to determine whether a block capture's lifetime should
1253   // end at the end of the full expression as opposed to the end of the scope
1254   // enclosing the block expression.
1255   //
1256   // This permits a small, easily-implemented exception to our over-conservative
1257   // rules about not jumping to statements following block literals with
1258   // non-trivial cleanups.
1259   SaveRetExprRAII SaveRetExpr(RV, *this);
1260 
1261   RunCleanupsScope cleanupScope(*this);
1262   if (const auto *EWC = dyn_cast_or_null<ExprWithCleanups>(RV))
1263     RV = EWC->getSubExpr();
1264   // FIXME: Clean this up by using an LValue for ReturnTemp,
1265   // EmitStoreThroughLValue, and EmitAnyExpr.
1266   // Check if the NRVO candidate was not globalized in OpenMP mode.
1267   if (getLangOpts().ElideConstructors && S.getNRVOCandidate() &&
1268       S.getNRVOCandidate()->isNRVOVariable() &&
1269       (!getLangOpts().OpenMP ||
1270        !CGM.getOpenMPRuntime()
1271             .getAddressOfLocalVariable(*this, S.getNRVOCandidate())
1272             .isValid())) {
1273     // Apply the named return value optimization for this return statement,
1274     // which means doing nothing: the appropriate result has already been
1275     // constructed into the NRVO variable.
1276 
1277     // If there is an NRVO flag for this variable, set it to 1 into indicate
1278     // that the cleanup code should not destroy the variable.
1279     if (llvm::Value *NRVOFlag = NRVOFlags[S.getNRVOCandidate()])
1280       Builder.CreateFlagStore(Builder.getTrue(), NRVOFlag);
1281   } else if (!ReturnValue.isValid() || (RV && RV->getType()->isVoidType())) {
1282     // Make sure not to return anything, but evaluate the expression
1283     // for side effects.
1284     if (RV) {
1285       EmitAnyExpr(RV);
1286       if (auto *CE = dyn_cast<CallExpr>(RV))
1287         makeTailCallIfSwiftAsync(CE, Builder, CurFnInfo);
1288     }
1289   } else if (!RV) {
1290     // Do nothing (return value is left uninitialized)
1291   } else if (FnRetTy->isReferenceType()) {
1292     // If this function returns a reference, take the address of the expression
1293     // rather than the value.
1294     RValue Result = EmitReferenceBindingToExpr(RV);
1295     Builder.CreateStore(Result.getScalarVal(), ReturnValue);
1296   } else {
1297     switch (getEvaluationKind(RV->getType())) {
1298     case TEK_Scalar:
1299       Builder.CreateStore(EmitScalarExpr(RV), ReturnValue);
1300       break;
1301     case TEK_Complex:
1302       EmitComplexExprIntoLValue(RV, MakeAddrLValue(ReturnValue, RV->getType()),
1303                                 /*isInit*/ true);
1304       break;
1305     case TEK_Aggregate:
1306       EmitAggExpr(RV, AggValueSlot::forAddr(
1307                           ReturnValue, Qualifiers(),
1308                           AggValueSlot::IsDestructed,
1309                           AggValueSlot::DoesNotNeedGCBarriers,
1310                           AggValueSlot::IsNotAliased,
1311                           getOverlapForReturnValue()));
1312       break;
1313     }
1314   }
1315 
1316   ++NumReturnExprs;
1317   if (!RV || RV->isEvaluatable(getContext()))
1318     ++NumSimpleReturnExprs;
1319 
1320   cleanupScope.ForceCleanup();
1321   EmitBranchThroughCleanup(ReturnBlock);
1322 }
1323 
EmitDeclStmt(const DeclStmt & S)1324 void CodeGenFunction::EmitDeclStmt(const DeclStmt &S) {
1325   // As long as debug info is modeled with instructions, we have to ensure we
1326   // have a place to insert here and write the stop point here.
1327   if (HaveInsertPoint())
1328     EmitStopPoint(&S);
1329 
1330   for (const auto *I : S.decls())
1331     EmitDecl(*I);
1332 }
1333 
EmitBreakStmt(const BreakStmt & S)1334 void CodeGenFunction::EmitBreakStmt(const BreakStmt &S) {
1335   assert(!BreakContinueStack.empty() && "break stmt not in a loop or switch!");
1336 
1337   // If this code is reachable then emit a stop point (if generating
1338   // debug info). We have to do this ourselves because we are on the
1339   // "simple" statement path.
1340   if (HaveInsertPoint())
1341     EmitStopPoint(&S);
1342 
1343   EmitBranchThroughCleanup(BreakContinueStack.back().BreakBlock);
1344 }
1345 
EmitContinueStmt(const ContinueStmt & S)1346 void CodeGenFunction::EmitContinueStmt(const ContinueStmt &S) {
1347   assert(!BreakContinueStack.empty() && "continue stmt not in a loop!");
1348 
1349   // If this code is reachable then emit a stop point (if generating
1350   // debug info). We have to do this ourselves because we are on the
1351   // "simple" statement path.
1352   if (HaveInsertPoint())
1353     EmitStopPoint(&S);
1354 
1355   EmitBranchThroughCleanup(BreakContinueStack.back().ContinueBlock);
1356 }
1357 
1358 /// EmitCaseStmtRange - If case statement range is not too big then
1359 /// add multiple cases to switch instruction, one for each value within
1360 /// the range. If range is too big then emit "if" condition check.
EmitCaseStmtRange(const CaseStmt & S,ArrayRef<const Attr * > Attrs)1361 void CodeGenFunction::EmitCaseStmtRange(const CaseStmt &S,
1362                                         ArrayRef<const Attr *> Attrs) {
1363   assert(S.getRHS() && "Expected RHS value in CaseStmt");
1364 
1365   llvm::APSInt LHS = S.getLHS()->EvaluateKnownConstInt(getContext());
1366   llvm::APSInt RHS = S.getRHS()->EvaluateKnownConstInt(getContext());
1367 
1368   // Emit the code for this case. We do this first to make sure it is
1369   // properly chained from our predecessor before generating the
1370   // switch machinery to enter this block.
1371   llvm::BasicBlock *CaseDest = createBasicBlock("sw.bb");
1372   EmitBlockWithFallThrough(CaseDest, &S);
1373   EmitStmt(S.getSubStmt());
1374 
1375   // If range is empty, do nothing.
1376   if (LHS.isSigned() ? RHS.slt(LHS) : RHS.ult(LHS))
1377     return;
1378 
1379   Stmt::Likelihood LH = Stmt::getLikelihood(Attrs);
1380   llvm::APInt Range = RHS - LHS;
1381   // FIXME: parameters such as this should not be hardcoded.
1382   if (Range.ult(llvm::APInt(Range.getBitWidth(), 64))) {
1383     // Range is small enough to add multiple switch instruction cases.
1384     uint64_t Total = getProfileCount(&S);
1385     unsigned NCases = Range.getZExtValue() + 1;
1386     // We only have one region counter for the entire set of cases here, so we
1387     // need to divide the weights evenly between the generated cases, ensuring
1388     // that the total weight is preserved. E.g., a weight of 5 over three cases
1389     // will be distributed as weights of 2, 2, and 1.
1390     uint64_t Weight = Total / NCases, Rem = Total % NCases;
1391     for (unsigned I = 0; I != NCases; ++I) {
1392       if (SwitchWeights)
1393         SwitchWeights->push_back(Weight + (Rem ? 1 : 0));
1394       else if (SwitchLikelihood)
1395         SwitchLikelihood->push_back(LH);
1396 
1397       if (Rem)
1398         Rem--;
1399       SwitchInsn->addCase(Builder.getInt(LHS), CaseDest);
1400       ++LHS;
1401     }
1402     return;
1403   }
1404 
1405   // The range is too big. Emit "if" condition into a new block,
1406   // making sure to save and restore the current insertion point.
1407   llvm::BasicBlock *RestoreBB = Builder.GetInsertBlock();
1408 
1409   // Push this test onto the chain of range checks (which terminates
1410   // in the default basic block). The switch's default will be changed
1411   // to the top of this chain after switch emission is complete.
1412   llvm::BasicBlock *FalseDest = CaseRangeBlock;
1413   CaseRangeBlock = createBasicBlock("sw.caserange");
1414 
1415   CurFn->getBasicBlockList().push_back(CaseRangeBlock);
1416   Builder.SetInsertPoint(CaseRangeBlock);
1417 
1418   // Emit range check.
1419   llvm::Value *Diff =
1420     Builder.CreateSub(SwitchInsn->getCondition(), Builder.getInt(LHS));
1421   llvm::Value *Cond =
1422     Builder.CreateICmpULE(Diff, Builder.getInt(Range), "inbounds");
1423 
1424   llvm::MDNode *Weights = nullptr;
1425   if (SwitchWeights) {
1426     uint64_t ThisCount = getProfileCount(&S);
1427     uint64_t DefaultCount = (*SwitchWeights)[0];
1428     Weights = createProfileWeights(ThisCount, DefaultCount);
1429 
1430     // Since we're chaining the switch default through each large case range, we
1431     // need to update the weight for the default, ie, the first case, to include
1432     // this case.
1433     (*SwitchWeights)[0] += ThisCount;
1434   } else if (SwitchLikelihood)
1435     Cond = emitCondLikelihoodViaExpectIntrinsic(Cond, LH);
1436 
1437   Builder.CreateCondBr(Cond, CaseDest, FalseDest, Weights);
1438 
1439   // Restore the appropriate insertion point.
1440   if (RestoreBB)
1441     Builder.SetInsertPoint(RestoreBB);
1442   else
1443     Builder.ClearInsertionPoint();
1444 }
1445 
EmitCaseStmt(const CaseStmt & S,ArrayRef<const Attr * > Attrs)1446 void CodeGenFunction::EmitCaseStmt(const CaseStmt &S,
1447                                    ArrayRef<const Attr *> Attrs) {
1448   // If there is no enclosing switch instance that we're aware of, then this
1449   // case statement and its block can be elided.  This situation only happens
1450   // when we've constant-folded the switch, are emitting the constant case,
1451   // and part of the constant case includes another case statement.  For
1452   // instance: switch (4) { case 4: do { case 5: } while (1); }
1453   if (!SwitchInsn) {
1454     EmitStmt(S.getSubStmt());
1455     return;
1456   }
1457 
1458   // Handle case ranges.
1459   if (S.getRHS()) {
1460     EmitCaseStmtRange(S, Attrs);
1461     return;
1462   }
1463 
1464   llvm::ConstantInt *CaseVal =
1465     Builder.getInt(S.getLHS()->EvaluateKnownConstInt(getContext()));
1466   if (SwitchLikelihood)
1467     SwitchLikelihood->push_back(Stmt::getLikelihood(Attrs));
1468 
1469   // If the body of the case is just a 'break', try to not emit an empty block.
1470   // If we're profiling or we're not optimizing, leave the block in for better
1471   // debug and coverage analysis.
1472   if (!CGM.getCodeGenOpts().hasProfileClangInstr() &&
1473       CGM.getCodeGenOpts().OptimizationLevel > 0 &&
1474       isa<BreakStmt>(S.getSubStmt())) {
1475     JumpDest Block = BreakContinueStack.back().BreakBlock;
1476 
1477     // Only do this optimization if there are no cleanups that need emitting.
1478     if (isObviouslyBranchWithoutCleanups(Block)) {
1479       if (SwitchWeights)
1480         SwitchWeights->push_back(getProfileCount(&S));
1481       SwitchInsn->addCase(CaseVal, Block.getBlock());
1482 
1483       // If there was a fallthrough into this case, make sure to redirect it to
1484       // the end of the switch as well.
1485       if (Builder.GetInsertBlock()) {
1486         Builder.CreateBr(Block.getBlock());
1487         Builder.ClearInsertionPoint();
1488       }
1489       return;
1490     }
1491   }
1492 
1493   llvm::BasicBlock *CaseDest = createBasicBlock("sw.bb");
1494   EmitBlockWithFallThrough(CaseDest, &S);
1495   if (SwitchWeights)
1496     SwitchWeights->push_back(getProfileCount(&S));
1497   SwitchInsn->addCase(CaseVal, CaseDest);
1498 
1499   // Recursively emitting the statement is acceptable, but is not wonderful for
1500   // code where we have many case statements nested together, i.e.:
1501   //  case 1:
1502   //    case 2:
1503   //      case 3: etc.
1504   // Handling this recursively will create a new block for each case statement
1505   // that falls through to the next case which is IR intensive.  It also causes
1506   // deep recursion which can run into stack depth limitations.  Handle
1507   // sequential non-range case statements specially.
1508   //
1509   // TODO When the next case has a likelihood attribute the code returns to the
1510   // recursive algorithm. Maybe improve this case if it becomes common practice
1511   // to use a lot of attributes.
1512   const CaseStmt *CurCase = &S;
1513   const CaseStmt *NextCase = dyn_cast<CaseStmt>(S.getSubStmt());
1514 
1515   // Otherwise, iteratively add consecutive cases to this switch stmt.
1516   while (NextCase && NextCase->getRHS() == nullptr) {
1517     CurCase = NextCase;
1518     llvm::ConstantInt *CaseVal =
1519       Builder.getInt(CurCase->getLHS()->EvaluateKnownConstInt(getContext()));
1520 
1521     if (SwitchWeights)
1522       SwitchWeights->push_back(getProfileCount(NextCase));
1523     if (CGM.getCodeGenOpts().hasProfileClangInstr()) {
1524       CaseDest = createBasicBlock("sw.bb");
1525       EmitBlockWithFallThrough(CaseDest, CurCase);
1526     }
1527     // Since this loop is only executed when the CaseStmt has no attributes
1528     // use a hard-coded value.
1529     if (SwitchLikelihood)
1530       SwitchLikelihood->push_back(Stmt::LH_None);
1531 
1532     SwitchInsn->addCase(CaseVal, CaseDest);
1533     NextCase = dyn_cast<CaseStmt>(CurCase->getSubStmt());
1534   }
1535 
1536   // Generate a stop point for debug info if the case statement is
1537   // followed by a default statement. A fallthrough case before a
1538   // default case gets its own branch target.
1539   if (CurCase->getSubStmt()->getStmtClass() == Stmt::DefaultStmtClass)
1540     EmitStopPoint(CurCase);
1541 
1542   // Normal default recursion for non-cases.
1543   EmitStmt(CurCase->getSubStmt());
1544 }
1545 
EmitDefaultStmt(const DefaultStmt & S,ArrayRef<const Attr * > Attrs)1546 void CodeGenFunction::EmitDefaultStmt(const DefaultStmt &S,
1547                                       ArrayRef<const Attr *> Attrs) {
1548   // If there is no enclosing switch instance that we're aware of, then this
1549   // default statement can be elided. This situation only happens when we've
1550   // constant-folded the switch.
1551   if (!SwitchInsn) {
1552     EmitStmt(S.getSubStmt());
1553     return;
1554   }
1555 
1556   llvm::BasicBlock *DefaultBlock = SwitchInsn->getDefaultDest();
1557   assert(DefaultBlock->empty() &&
1558          "EmitDefaultStmt: Default block already defined?");
1559 
1560   if (SwitchLikelihood)
1561     SwitchLikelihood->front() = Stmt::getLikelihood(Attrs);
1562 
1563   EmitBlockWithFallThrough(DefaultBlock, &S);
1564 
1565   EmitStmt(S.getSubStmt());
1566 }
1567 
1568 /// CollectStatementsForCase - Given the body of a 'switch' statement and a
1569 /// constant value that is being switched on, see if we can dead code eliminate
1570 /// the body of the switch to a simple series of statements to emit.  Basically,
1571 /// on a switch (5) we want to find these statements:
1572 ///    case 5:
1573 ///      printf(...);    <--
1574 ///      ++i;            <--
1575 ///      break;
1576 ///
1577 /// and add them to the ResultStmts vector.  If it is unsafe to do this
1578 /// transformation (for example, one of the elided statements contains a label
1579 /// that might be jumped to), return CSFC_Failure.  If we handled it and 'S'
1580 /// should include statements after it (e.g. the printf() line is a substmt of
1581 /// the case) then return CSFC_FallThrough.  If we handled it and found a break
1582 /// statement, then return CSFC_Success.
1583 ///
1584 /// If Case is non-null, then we are looking for the specified case, checking
1585 /// that nothing we jump over contains labels.  If Case is null, then we found
1586 /// the case and are looking for the break.
1587 ///
1588 /// If the recursive walk actually finds our Case, then we set FoundCase to
1589 /// true.
1590 ///
1591 enum CSFC_Result { CSFC_Failure, CSFC_FallThrough, CSFC_Success };
CollectStatementsForCase(const Stmt * S,const SwitchCase * Case,bool & FoundCase,SmallVectorImpl<const Stmt * > & ResultStmts)1592 static CSFC_Result CollectStatementsForCase(const Stmt *S,
1593                                             const SwitchCase *Case,
1594                                             bool &FoundCase,
1595                               SmallVectorImpl<const Stmt*> &ResultStmts) {
1596   // If this is a null statement, just succeed.
1597   if (!S)
1598     return Case ? CSFC_Success : CSFC_FallThrough;
1599 
1600   // If this is the switchcase (case 4: or default) that we're looking for, then
1601   // we're in business.  Just add the substatement.
1602   if (const SwitchCase *SC = dyn_cast<SwitchCase>(S)) {
1603     if (S == Case) {
1604       FoundCase = true;
1605       return CollectStatementsForCase(SC->getSubStmt(), nullptr, FoundCase,
1606                                       ResultStmts);
1607     }
1608 
1609     // Otherwise, this is some other case or default statement, just ignore it.
1610     return CollectStatementsForCase(SC->getSubStmt(), Case, FoundCase,
1611                                     ResultStmts);
1612   }
1613 
1614   // If we are in the live part of the code and we found our break statement,
1615   // return a success!
1616   if (!Case && isa<BreakStmt>(S))
1617     return CSFC_Success;
1618 
1619   // If this is a switch statement, then it might contain the SwitchCase, the
1620   // break, or neither.
1621   if (const CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) {
1622     // Handle this as two cases: we might be looking for the SwitchCase (if so
1623     // the skipped statements must be skippable) or we might already have it.
1624     CompoundStmt::const_body_iterator I = CS->body_begin(), E = CS->body_end();
1625     bool StartedInLiveCode = FoundCase;
1626     unsigned StartSize = ResultStmts.size();
1627 
1628     // If we've not found the case yet, scan through looking for it.
1629     if (Case) {
1630       // Keep track of whether we see a skipped declaration.  The code could be
1631       // using the declaration even if it is skipped, so we can't optimize out
1632       // the decl if the kept statements might refer to it.
1633       bool HadSkippedDecl = false;
1634 
1635       // If we're looking for the case, just see if we can skip each of the
1636       // substatements.
1637       for (; Case && I != E; ++I) {
1638         HadSkippedDecl |= CodeGenFunction::mightAddDeclToScope(*I);
1639 
1640         switch (CollectStatementsForCase(*I, Case, FoundCase, ResultStmts)) {
1641         case CSFC_Failure: return CSFC_Failure;
1642         case CSFC_Success:
1643           // A successful result means that either 1) that the statement doesn't
1644           // have the case and is skippable, or 2) does contain the case value
1645           // and also contains the break to exit the switch.  In the later case,
1646           // we just verify the rest of the statements are elidable.
1647           if (FoundCase) {
1648             // If we found the case and skipped declarations, we can't do the
1649             // optimization.
1650             if (HadSkippedDecl)
1651               return CSFC_Failure;
1652 
1653             for (++I; I != E; ++I)
1654               if (CodeGenFunction::ContainsLabel(*I, true))
1655                 return CSFC_Failure;
1656             return CSFC_Success;
1657           }
1658           break;
1659         case CSFC_FallThrough:
1660           // If we have a fallthrough condition, then we must have found the
1661           // case started to include statements.  Consider the rest of the
1662           // statements in the compound statement as candidates for inclusion.
1663           assert(FoundCase && "Didn't find case but returned fallthrough?");
1664           // We recursively found Case, so we're not looking for it anymore.
1665           Case = nullptr;
1666 
1667           // If we found the case and skipped declarations, we can't do the
1668           // optimization.
1669           if (HadSkippedDecl)
1670             return CSFC_Failure;
1671           break;
1672         }
1673       }
1674 
1675       if (!FoundCase)
1676         return CSFC_Success;
1677 
1678       assert(!HadSkippedDecl && "fallthrough after skipping decl");
1679     }
1680 
1681     // If we have statements in our range, then we know that the statements are
1682     // live and need to be added to the set of statements we're tracking.
1683     bool AnyDecls = false;
1684     for (; I != E; ++I) {
1685       AnyDecls |= CodeGenFunction::mightAddDeclToScope(*I);
1686 
1687       switch (CollectStatementsForCase(*I, nullptr, FoundCase, ResultStmts)) {
1688       case CSFC_Failure: return CSFC_Failure;
1689       case CSFC_FallThrough:
1690         // A fallthrough result means that the statement was simple and just
1691         // included in ResultStmt, keep adding them afterwards.
1692         break;
1693       case CSFC_Success:
1694         // A successful result means that we found the break statement and
1695         // stopped statement inclusion.  We just ensure that any leftover stmts
1696         // are skippable and return success ourselves.
1697         for (++I; I != E; ++I)
1698           if (CodeGenFunction::ContainsLabel(*I, true))
1699             return CSFC_Failure;
1700         return CSFC_Success;
1701       }
1702     }
1703 
1704     // If we're about to fall out of a scope without hitting a 'break;', we
1705     // can't perform the optimization if there were any decls in that scope
1706     // (we'd lose their end-of-lifetime).
1707     if (AnyDecls) {
1708       // If the entire compound statement was live, there's one more thing we
1709       // can try before giving up: emit the whole thing as a single statement.
1710       // We can do that unless the statement contains a 'break;'.
1711       // FIXME: Such a break must be at the end of a construct within this one.
1712       // We could emit this by just ignoring the BreakStmts entirely.
1713       if (StartedInLiveCode && !CodeGenFunction::containsBreak(S)) {
1714         ResultStmts.resize(StartSize);
1715         ResultStmts.push_back(S);
1716       } else {
1717         return CSFC_Failure;
1718       }
1719     }
1720 
1721     return CSFC_FallThrough;
1722   }
1723 
1724   // Okay, this is some other statement that we don't handle explicitly, like a
1725   // for statement or increment etc.  If we are skipping over this statement,
1726   // just verify it doesn't have labels, which would make it invalid to elide.
1727   if (Case) {
1728     if (CodeGenFunction::ContainsLabel(S, true))
1729       return CSFC_Failure;
1730     return CSFC_Success;
1731   }
1732 
1733   // Otherwise, we want to include this statement.  Everything is cool with that
1734   // so long as it doesn't contain a break out of the switch we're in.
1735   if (CodeGenFunction::containsBreak(S)) return CSFC_Failure;
1736 
1737   // Otherwise, everything is great.  Include the statement and tell the caller
1738   // that we fall through and include the next statement as well.
1739   ResultStmts.push_back(S);
1740   return CSFC_FallThrough;
1741 }
1742 
1743 /// FindCaseStatementsForValue - Find the case statement being jumped to and
1744 /// then invoke CollectStatementsForCase to find the list of statements to emit
1745 /// for a switch on constant.  See the comment above CollectStatementsForCase
1746 /// for more details.
FindCaseStatementsForValue(const SwitchStmt & S,const llvm::APSInt & ConstantCondValue,SmallVectorImpl<const Stmt * > & ResultStmts,ASTContext & C,const SwitchCase * & ResultCase)1747 static bool FindCaseStatementsForValue(const SwitchStmt &S,
1748                                        const llvm::APSInt &ConstantCondValue,
1749                                 SmallVectorImpl<const Stmt*> &ResultStmts,
1750                                        ASTContext &C,
1751                                        const SwitchCase *&ResultCase) {
1752   // First step, find the switch case that is being branched to.  We can do this
1753   // efficiently by scanning the SwitchCase list.
1754   const SwitchCase *Case = S.getSwitchCaseList();
1755   const DefaultStmt *DefaultCase = nullptr;
1756 
1757   for (; Case; Case = Case->getNextSwitchCase()) {
1758     // It's either a default or case.  Just remember the default statement in
1759     // case we're not jumping to any numbered cases.
1760     if (const DefaultStmt *DS = dyn_cast<DefaultStmt>(Case)) {
1761       DefaultCase = DS;
1762       continue;
1763     }
1764 
1765     // Check to see if this case is the one we're looking for.
1766     const CaseStmt *CS = cast<CaseStmt>(Case);
1767     // Don't handle case ranges yet.
1768     if (CS->getRHS()) return false;
1769 
1770     // If we found our case, remember it as 'case'.
1771     if (CS->getLHS()->EvaluateKnownConstInt(C) == ConstantCondValue)
1772       break;
1773   }
1774 
1775   // If we didn't find a matching case, we use a default if it exists, or we
1776   // elide the whole switch body!
1777   if (!Case) {
1778     // It is safe to elide the body of the switch if it doesn't contain labels
1779     // etc.  If it is safe, return successfully with an empty ResultStmts list.
1780     if (!DefaultCase)
1781       return !CodeGenFunction::ContainsLabel(&S);
1782     Case = DefaultCase;
1783   }
1784 
1785   // Ok, we know which case is being jumped to, try to collect all the
1786   // statements that follow it.  This can fail for a variety of reasons.  Also,
1787   // check to see that the recursive walk actually found our case statement.
1788   // Insane cases like this can fail to find it in the recursive walk since we
1789   // don't handle every stmt kind:
1790   // switch (4) {
1791   //   while (1) {
1792   //     case 4: ...
1793   bool FoundCase = false;
1794   ResultCase = Case;
1795   return CollectStatementsForCase(S.getBody(), Case, FoundCase,
1796                                   ResultStmts) != CSFC_Failure &&
1797          FoundCase;
1798 }
1799 
1800 static Optional<SmallVector<uint64_t, 16>>
getLikelihoodWeights(ArrayRef<Stmt::Likelihood> Likelihoods)1801 getLikelihoodWeights(ArrayRef<Stmt::Likelihood> Likelihoods) {
1802   // Are there enough branches to weight them?
1803   if (Likelihoods.size() <= 1)
1804     return None;
1805 
1806   uint64_t NumUnlikely = 0;
1807   uint64_t NumNone = 0;
1808   uint64_t NumLikely = 0;
1809   for (const auto LH : Likelihoods) {
1810     switch (LH) {
1811     case Stmt::LH_Unlikely:
1812       ++NumUnlikely;
1813       break;
1814     case Stmt::LH_None:
1815       ++NumNone;
1816       break;
1817     case Stmt::LH_Likely:
1818       ++NumLikely;
1819       break;
1820     }
1821   }
1822 
1823   // Is there a likelihood attribute used?
1824   if (NumUnlikely == 0 && NumLikely == 0)
1825     return None;
1826 
1827   // When multiple cases share the same code they can be combined during
1828   // optimization. In that case the weights of the branch will be the sum of
1829   // the individual weights. Make sure the combined sum of all neutral cases
1830   // doesn't exceed the value of a single likely attribute.
1831   // The additions both avoid divisions by 0 and make sure the weights of None
1832   // don't exceed the weight of Likely.
1833   const uint64_t Likely = INT32_MAX / (NumLikely + 2);
1834   const uint64_t None = Likely / (NumNone + 1);
1835   const uint64_t Unlikely = 0;
1836 
1837   SmallVector<uint64_t, 16> Result;
1838   Result.reserve(Likelihoods.size());
1839   for (const auto LH : Likelihoods) {
1840     switch (LH) {
1841     case Stmt::LH_Unlikely:
1842       Result.push_back(Unlikely);
1843       break;
1844     case Stmt::LH_None:
1845       Result.push_back(None);
1846       break;
1847     case Stmt::LH_Likely:
1848       Result.push_back(Likely);
1849       break;
1850     }
1851   }
1852 
1853   return Result;
1854 }
1855 
EmitSwitchStmt(const SwitchStmt & S)1856 void CodeGenFunction::EmitSwitchStmt(const SwitchStmt &S) {
1857   // Handle nested switch statements.
1858   llvm::SwitchInst *SavedSwitchInsn = SwitchInsn;
1859   SmallVector<uint64_t, 16> *SavedSwitchWeights = SwitchWeights;
1860   SmallVector<Stmt::Likelihood, 16> *SavedSwitchLikelihood = SwitchLikelihood;
1861   llvm::BasicBlock *SavedCRBlock = CaseRangeBlock;
1862 
1863   // See if we can constant fold the condition of the switch and therefore only
1864   // emit the live case statement (if any) of the switch.
1865   llvm::APSInt ConstantCondValue;
1866   if (ConstantFoldsToSimpleInteger(S.getCond(), ConstantCondValue)) {
1867     SmallVector<const Stmt*, 4> CaseStmts;
1868     const SwitchCase *Case = nullptr;
1869     if (FindCaseStatementsForValue(S, ConstantCondValue, CaseStmts,
1870                                    getContext(), Case)) {
1871       if (Case)
1872         incrementProfileCounter(Case);
1873       RunCleanupsScope ExecutedScope(*this);
1874 
1875       if (S.getInit())
1876         EmitStmt(S.getInit());
1877 
1878       // Emit the condition variable if needed inside the entire cleanup scope
1879       // used by this special case for constant folded switches.
1880       if (S.getConditionVariable())
1881         EmitDecl(*S.getConditionVariable());
1882 
1883       // At this point, we are no longer "within" a switch instance, so
1884       // we can temporarily enforce this to ensure that any embedded case
1885       // statements are not emitted.
1886       SwitchInsn = nullptr;
1887 
1888       // Okay, we can dead code eliminate everything except this case.  Emit the
1889       // specified series of statements and we're good.
1890       for (unsigned i = 0, e = CaseStmts.size(); i != e; ++i)
1891         EmitStmt(CaseStmts[i]);
1892       incrementProfileCounter(&S);
1893 
1894       // Now we want to restore the saved switch instance so that nested
1895       // switches continue to function properly
1896       SwitchInsn = SavedSwitchInsn;
1897 
1898       return;
1899     }
1900   }
1901 
1902   JumpDest SwitchExit = getJumpDestInCurrentScope("sw.epilog");
1903 
1904   RunCleanupsScope ConditionScope(*this);
1905 
1906   if (S.getInit())
1907     EmitStmt(S.getInit());
1908 
1909   if (S.getConditionVariable())
1910     EmitDecl(*S.getConditionVariable());
1911   llvm::Value *CondV = EmitScalarExpr(S.getCond());
1912 
1913   // Create basic block to hold stuff that comes after switch
1914   // statement. We also need to create a default block now so that
1915   // explicit case ranges tests can have a place to jump to on
1916   // failure.
1917   llvm::BasicBlock *DefaultBlock = createBasicBlock("sw.default");
1918   SwitchInsn = Builder.CreateSwitch(CondV, DefaultBlock);
1919   if (PGO.haveRegionCounts()) {
1920     // Walk the SwitchCase list to find how many there are.
1921     uint64_t DefaultCount = 0;
1922     unsigned NumCases = 0;
1923     for (const SwitchCase *Case = S.getSwitchCaseList();
1924          Case;
1925          Case = Case->getNextSwitchCase()) {
1926       if (isa<DefaultStmt>(Case))
1927         DefaultCount = getProfileCount(Case);
1928       NumCases += 1;
1929     }
1930     SwitchWeights = new SmallVector<uint64_t, 16>();
1931     SwitchWeights->reserve(NumCases);
1932     // The default needs to be first. We store the edge count, so we already
1933     // know the right weight.
1934     SwitchWeights->push_back(DefaultCount);
1935   } else if (CGM.getCodeGenOpts().OptimizationLevel) {
1936     SwitchLikelihood = new SmallVector<Stmt::Likelihood, 16>();
1937     // Initialize the default case.
1938     SwitchLikelihood->push_back(Stmt::LH_None);
1939   }
1940 
1941   CaseRangeBlock = DefaultBlock;
1942 
1943   // Clear the insertion point to indicate we are in unreachable code.
1944   Builder.ClearInsertionPoint();
1945 
1946   // All break statements jump to NextBlock. If BreakContinueStack is non-empty
1947   // then reuse last ContinueBlock.
1948   JumpDest OuterContinue;
1949   if (!BreakContinueStack.empty())
1950     OuterContinue = BreakContinueStack.back().ContinueBlock;
1951 
1952   BreakContinueStack.push_back(BreakContinue(SwitchExit, OuterContinue));
1953 
1954   // Emit switch body.
1955   EmitStmt(S.getBody());
1956 
1957   BreakContinueStack.pop_back();
1958 
1959   // Update the default block in case explicit case range tests have
1960   // been chained on top.
1961   SwitchInsn->setDefaultDest(CaseRangeBlock);
1962 
1963   // If a default was never emitted:
1964   if (!DefaultBlock->getParent()) {
1965     // If we have cleanups, emit the default block so that there's a
1966     // place to jump through the cleanups from.
1967     if (ConditionScope.requiresCleanups()) {
1968       EmitBlock(DefaultBlock);
1969 
1970     // Otherwise, just forward the default block to the switch end.
1971     } else {
1972       DefaultBlock->replaceAllUsesWith(SwitchExit.getBlock());
1973       delete DefaultBlock;
1974     }
1975   }
1976 
1977   ConditionScope.ForceCleanup();
1978 
1979   // Emit continuation.
1980   EmitBlock(SwitchExit.getBlock(), true);
1981   incrementProfileCounter(&S);
1982 
1983   // If the switch has a condition wrapped by __builtin_unpredictable,
1984   // create metadata that specifies that the switch is unpredictable.
1985   // Don't bother if not optimizing because that metadata would not be used.
1986   auto *Call = dyn_cast<CallExpr>(S.getCond());
1987   if (Call && CGM.getCodeGenOpts().OptimizationLevel != 0) {
1988     auto *FD = dyn_cast_or_null<FunctionDecl>(Call->getCalleeDecl());
1989     if (FD && FD->getBuiltinID() == Builtin::BI__builtin_unpredictable) {
1990       llvm::MDBuilder MDHelper(getLLVMContext());
1991       SwitchInsn->setMetadata(llvm::LLVMContext::MD_unpredictable,
1992                               MDHelper.createUnpredictable());
1993     }
1994   }
1995 
1996   if (SwitchWeights) {
1997     assert(SwitchWeights->size() == 1 + SwitchInsn->getNumCases() &&
1998            "switch weights do not match switch cases");
1999     // If there's only one jump destination there's no sense weighting it.
2000     if (SwitchWeights->size() > 1)
2001       SwitchInsn->setMetadata(llvm::LLVMContext::MD_prof,
2002                               createProfileWeights(*SwitchWeights));
2003     delete SwitchWeights;
2004   } else if (SwitchLikelihood) {
2005     assert(SwitchLikelihood->size() == 1 + SwitchInsn->getNumCases() &&
2006            "switch likelihoods do not match switch cases");
2007     Optional<SmallVector<uint64_t, 16>> LHW =
2008         getLikelihoodWeights(*SwitchLikelihood);
2009     if (LHW) {
2010       llvm::MDBuilder MDHelper(CGM.getLLVMContext());
2011       SwitchInsn->setMetadata(llvm::LLVMContext::MD_prof,
2012                               createProfileWeights(*LHW));
2013     }
2014     delete SwitchLikelihood;
2015   }
2016   SwitchInsn = SavedSwitchInsn;
2017   SwitchWeights = SavedSwitchWeights;
2018   SwitchLikelihood = SavedSwitchLikelihood;
2019   CaseRangeBlock = SavedCRBlock;
2020 }
2021 
2022 static std::string
SimplifyConstraint(const char * Constraint,const TargetInfo & Target,SmallVectorImpl<TargetInfo::ConstraintInfo> * OutCons=nullptr)2023 SimplifyConstraint(const char *Constraint, const TargetInfo &Target,
2024                  SmallVectorImpl<TargetInfo::ConstraintInfo> *OutCons=nullptr) {
2025   std::string Result;
2026 
2027   while (*Constraint) {
2028     switch (*Constraint) {
2029     default:
2030       Result += Target.convertConstraint(Constraint);
2031       break;
2032     // Ignore these
2033     case '*':
2034     case '?':
2035     case '!':
2036     case '=': // Will see this and the following in mult-alt constraints.
2037     case '+':
2038       break;
2039     case '#': // Ignore the rest of the constraint alternative.
2040       while (Constraint[1] && Constraint[1] != ',')
2041         Constraint++;
2042       break;
2043     case '&':
2044     case '%':
2045       Result += *Constraint;
2046       while (Constraint[1] && Constraint[1] == *Constraint)
2047         Constraint++;
2048       break;
2049     case ',':
2050       Result += "|";
2051       break;
2052     case 'g':
2053       Result += "imr";
2054       break;
2055     case '[': {
2056       assert(OutCons &&
2057              "Must pass output names to constraints with a symbolic name");
2058       unsigned Index;
2059       bool result = Target.resolveSymbolicName(Constraint, *OutCons, Index);
2060       assert(result && "Could not resolve symbolic name"); (void)result;
2061       Result += llvm::utostr(Index);
2062       break;
2063     }
2064     }
2065 
2066     Constraint++;
2067   }
2068 
2069   return Result;
2070 }
2071 
2072 /// AddVariableConstraints - Look at AsmExpr and if it is a variable declared
2073 /// as using a particular register add that as a constraint that will be used
2074 /// in this asm stmt.
2075 static std::string
AddVariableConstraints(const std::string & Constraint,const Expr & AsmExpr,const TargetInfo & Target,CodeGenModule & CGM,const AsmStmt & Stmt,const bool EarlyClobber,std::string * GCCReg=nullptr)2076 AddVariableConstraints(const std::string &Constraint, const Expr &AsmExpr,
2077                        const TargetInfo &Target, CodeGenModule &CGM,
2078                        const AsmStmt &Stmt, const bool EarlyClobber,
2079                        std::string *GCCReg = nullptr) {
2080   const DeclRefExpr *AsmDeclRef = dyn_cast<DeclRefExpr>(&AsmExpr);
2081   if (!AsmDeclRef)
2082     return Constraint;
2083   const ValueDecl &Value = *AsmDeclRef->getDecl();
2084   const VarDecl *Variable = dyn_cast<VarDecl>(&Value);
2085   if (!Variable)
2086     return Constraint;
2087   if (Variable->getStorageClass() != SC_Register)
2088     return Constraint;
2089   AsmLabelAttr *Attr = Variable->getAttr<AsmLabelAttr>();
2090   if (!Attr)
2091     return Constraint;
2092   StringRef Register = Attr->getLabel();
2093   assert(Target.isValidGCCRegisterName(Register));
2094   // We're using validateOutputConstraint here because we only care if
2095   // this is a register constraint.
2096   TargetInfo::ConstraintInfo Info(Constraint, "");
2097   if (Target.validateOutputConstraint(Info) &&
2098       !Info.allowsRegister()) {
2099     CGM.ErrorUnsupported(&Stmt, "__asm__");
2100     return Constraint;
2101   }
2102   // Canonicalize the register here before returning it.
2103   Register = Target.getNormalizedGCCRegisterName(Register);
2104   if (GCCReg != nullptr)
2105     *GCCReg = Register.str();
2106   return (EarlyClobber ? "&{" : "{") + Register.str() + "}";
2107 }
2108 
2109 llvm::Value*
EmitAsmInputLValue(const TargetInfo::ConstraintInfo & Info,LValue InputValue,QualType InputType,std::string & ConstraintStr,SourceLocation Loc)2110 CodeGenFunction::EmitAsmInputLValue(const TargetInfo::ConstraintInfo &Info,
2111                                     LValue InputValue, QualType InputType,
2112                                     std::string &ConstraintStr,
2113                                     SourceLocation Loc) {
2114   llvm::Value *Arg;
2115   if (Info.allowsRegister() || !Info.allowsMemory()) {
2116     if (CodeGenFunction::hasScalarEvaluationKind(InputType)) {
2117       Arg = EmitLoadOfLValue(InputValue, Loc).getScalarVal();
2118     } else {
2119       llvm::Type *Ty = ConvertType(InputType);
2120       uint64_t Size = CGM.getDataLayout().getTypeSizeInBits(Ty);
2121       if ((Size <= 64 && llvm::isPowerOf2_64(Size)) ||
2122           getTargetHooks().isScalarizableAsmOperand(*this, Ty)) {
2123         Ty = llvm::IntegerType::get(getLLVMContext(), Size);
2124         Ty = llvm::PointerType::getUnqual(Ty);
2125 
2126         Arg = Builder.CreateLoad(
2127             Builder.CreateBitCast(InputValue.getAddress(*this), Ty));
2128       } else {
2129         Arg = InputValue.getPointer(*this);
2130         ConstraintStr += '*';
2131       }
2132     }
2133   } else {
2134     Arg = InputValue.getPointer(*this);
2135     ConstraintStr += '*';
2136   }
2137 
2138   return Arg;
2139 }
2140 
EmitAsmInput(const TargetInfo::ConstraintInfo & Info,const Expr * InputExpr,std::string & ConstraintStr)2141 llvm::Value* CodeGenFunction::EmitAsmInput(
2142                                          const TargetInfo::ConstraintInfo &Info,
2143                                            const Expr *InputExpr,
2144                                            std::string &ConstraintStr) {
2145   // If this can't be a register or memory, i.e., has to be a constant
2146   // (immediate or symbolic), try to emit it as such.
2147   if (!Info.allowsRegister() && !Info.allowsMemory()) {
2148     if (Info.requiresImmediateConstant()) {
2149       Expr::EvalResult EVResult;
2150       InputExpr->EvaluateAsRValue(EVResult, getContext(), true);
2151 
2152       llvm::APSInt IntResult;
2153       if (EVResult.Val.toIntegralConstant(IntResult, InputExpr->getType(),
2154                                           getContext()))
2155         return llvm::ConstantInt::get(getLLVMContext(), IntResult);
2156     }
2157 
2158     Expr::EvalResult Result;
2159     if (InputExpr->EvaluateAsInt(Result, getContext()))
2160       return llvm::ConstantInt::get(getLLVMContext(), Result.Val.getInt());
2161   }
2162 
2163   if (Info.allowsRegister() || !Info.allowsMemory())
2164     if (CodeGenFunction::hasScalarEvaluationKind(InputExpr->getType()))
2165       return EmitScalarExpr(InputExpr);
2166   if (InputExpr->getStmtClass() == Expr::CXXThisExprClass)
2167     return EmitScalarExpr(InputExpr);
2168   InputExpr = InputExpr->IgnoreParenNoopCasts(getContext());
2169   LValue Dest = EmitLValue(InputExpr);
2170   return EmitAsmInputLValue(Info, Dest, InputExpr->getType(), ConstraintStr,
2171                             InputExpr->getExprLoc());
2172 }
2173 
2174 /// getAsmSrcLocInfo - Return the !srcloc metadata node to attach to an inline
2175 /// asm call instruction.  The !srcloc MDNode contains a list of constant
2176 /// integers which are the source locations of the start of each line in the
2177 /// asm.
getAsmSrcLocInfo(const StringLiteral * Str,CodeGenFunction & CGF)2178 static llvm::MDNode *getAsmSrcLocInfo(const StringLiteral *Str,
2179                                       CodeGenFunction &CGF) {
2180   SmallVector<llvm::Metadata *, 8> Locs;
2181   // Add the location of the first line to the MDNode.
2182   Locs.push_back(llvm::ConstantAsMetadata::get(llvm::ConstantInt::get(
2183       CGF.Int64Ty, Str->getBeginLoc().getRawEncoding())));
2184   StringRef StrVal = Str->getString();
2185   if (!StrVal.empty()) {
2186     const SourceManager &SM = CGF.CGM.getContext().getSourceManager();
2187     const LangOptions &LangOpts = CGF.CGM.getLangOpts();
2188     unsigned StartToken = 0;
2189     unsigned ByteOffset = 0;
2190 
2191     // Add the location of the start of each subsequent line of the asm to the
2192     // MDNode.
2193     for (unsigned i = 0, e = StrVal.size() - 1; i != e; ++i) {
2194       if (StrVal[i] != '\n') continue;
2195       SourceLocation LineLoc = Str->getLocationOfByte(
2196           i + 1, SM, LangOpts, CGF.getTarget(), &StartToken, &ByteOffset);
2197       Locs.push_back(llvm::ConstantAsMetadata::get(
2198           llvm::ConstantInt::get(CGF.Int64Ty, LineLoc.getRawEncoding())));
2199     }
2200   }
2201 
2202   return llvm::MDNode::get(CGF.getLLVMContext(), Locs);
2203 }
2204 
UpdateAsmCallInst(llvm::CallBase & Result,bool HasSideEffect,bool HasUnwindClobber,bool ReadOnly,bool ReadNone,bool NoMerge,const AsmStmt & S,const std::vector<llvm::Type * > & ResultRegTypes,CodeGenFunction & CGF,std::vector<llvm::Value * > & RegResults)2205 static void UpdateAsmCallInst(llvm::CallBase &Result, bool HasSideEffect,
2206                               bool HasUnwindClobber, bool ReadOnly,
2207                               bool ReadNone, bool NoMerge, const AsmStmt &S,
2208                               const std::vector<llvm::Type *> &ResultRegTypes,
2209                               CodeGenFunction &CGF,
2210                               std::vector<llvm::Value *> &RegResults) {
2211   if (!HasUnwindClobber)
2212     Result.addFnAttr(llvm::Attribute::NoUnwind);
2213 
2214   if (NoMerge)
2215     Result.addFnAttr(llvm::Attribute::NoMerge);
2216   // Attach readnone and readonly attributes.
2217   if (!HasSideEffect) {
2218     if (ReadNone)
2219       Result.addFnAttr(llvm::Attribute::ReadNone);
2220     else if (ReadOnly)
2221       Result.addFnAttr(llvm::Attribute::ReadOnly);
2222   }
2223 
2224   // Attach OpenMP assumption attributes from the caller, if they exist.
2225   if (CGF.CGM.getLangOpts().OpenMP) {
2226     SmallVector<StringRef, 4> Attrs;
2227 
2228     for (const AssumptionAttr *AA :
2229          CGF.CurFuncDecl->specific_attrs<AssumptionAttr>())
2230       AA->getAssumption().split(Attrs, ",");
2231 
2232     if (!Attrs.empty())
2233       Result.addFnAttr(
2234           llvm::Attribute::get(CGF.getLLVMContext(), llvm::AssumptionAttrKey,
2235                                llvm::join(Attrs.begin(), Attrs.end(), ",")));
2236   }
2237 
2238   // Slap the source location of the inline asm into a !srcloc metadata on the
2239   // call.
2240   if (const auto *gccAsmStmt = dyn_cast<GCCAsmStmt>(&S))
2241     Result.setMetadata("srcloc",
2242                        getAsmSrcLocInfo(gccAsmStmt->getAsmString(), CGF));
2243   else {
2244     // At least put the line number on MS inline asm blobs.
2245     llvm::Constant *Loc =
2246         llvm::ConstantInt::get(CGF.Int64Ty, S.getAsmLoc().getRawEncoding());
2247     Result.setMetadata("srcloc",
2248                        llvm::MDNode::get(CGF.getLLVMContext(),
2249                                          llvm::ConstantAsMetadata::get(Loc)));
2250   }
2251 
2252   if (CGF.getLangOpts().assumeFunctionsAreConvergent())
2253     // Conservatively, mark all inline asm blocks in CUDA or OpenCL as
2254     // convergent (meaning, they may call an intrinsically convergent op, such
2255     // as bar.sync, and so can't have certain optimizations applied around
2256     // them).
2257     Result.addFnAttr(llvm::Attribute::Convergent);
2258   // Extract all of the register value results from the asm.
2259   if (ResultRegTypes.size() == 1) {
2260     RegResults.push_back(&Result);
2261   } else {
2262     for (unsigned i = 0, e = ResultRegTypes.size(); i != e; ++i) {
2263       llvm::Value *Tmp = CGF.Builder.CreateExtractValue(&Result, i, "asmresult");
2264       RegResults.push_back(Tmp);
2265     }
2266   }
2267 }
2268 
EmitAsmStmt(const AsmStmt & S)2269 void CodeGenFunction::EmitAsmStmt(const AsmStmt &S) {
2270   // Assemble the final asm string.
2271   std::string AsmString = S.generateAsmString(getContext());
2272 
2273   // Get all the output and input constraints together.
2274   SmallVector<TargetInfo::ConstraintInfo, 4> OutputConstraintInfos;
2275   SmallVector<TargetInfo::ConstraintInfo, 4> InputConstraintInfos;
2276 
2277   for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) {
2278     StringRef Name;
2279     if (const GCCAsmStmt *GAS = dyn_cast<GCCAsmStmt>(&S))
2280       Name = GAS->getOutputName(i);
2281     TargetInfo::ConstraintInfo Info(S.getOutputConstraint(i), Name);
2282     bool IsValid = getTarget().validateOutputConstraint(Info); (void)IsValid;
2283     assert(IsValid && "Failed to parse output constraint");
2284     OutputConstraintInfos.push_back(Info);
2285   }
2286 
2287   for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) {
2288     StringRef Name;
2289     if (const GCCAsmStmt *GAS = dyn_cast<GCCAsmStmt>(&S))
2290       Name = GAS->getInputName(i);
2291     TargetInfo::ConstraintInfo Info(S.getInputConstraint(i), Name);
2292     bool IsValid =
2293       getTarget().validateInputConstraint(OutputConstraintInfos, Info);
2294     assert(IsValid && "Failed to parse input constraint"); (void)IsValid;
2295     InputConstraintInfos.push_back(Info);
2296   }
2297 
2298   std::string Constraints;
2299 
2300   std::vector<LValue> ResultRegDests;
2301   std::vector<QualType> ResultRegQualTys;
2302   std::vector<llvm::Type *> ResultRegTypes;
2303   std::vector<llvm::Type *> ResultTruncRegTypes;
2304   std::vector<llvm::Type *> ArgTypes;
2305   std::vector<llvm::Value*> Args;
2306   llvm::BitVector ResultTypeRequiresCast;
2307 
2308   // Keep track of inout constraints.
2309   std::string InOutConstraints;
2310   std::vector<llvm::Value*> InOutArgs;
2311   std::vector<llvm::Type*> InOutArgTypes;
2312 
2313   // Keep track of out constraints for tied input operand.
2314   std::vector<std::string> OutputConstraints;
2315 
2316   // Keep track of defined physregs.
2317   llvm::SmallSet<std::string, 8> PhysRegOutputs;
2318 
2319   // An inline asm can be marked readonly if it meets the following conditions:
2320   //  - it doesn't have any sideeffects
2321   //  - it doesn't clobber memory
2322   //  - it doesn't return a value by-reference
2323   // It can be marked readnone if it doesn't have any input memory constraints
2324   // in addition to meeting the conditions listed above.
2325   bool ReadOnly = true, ReadNone = true;
2326 
2327   for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) {
2328     TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];
2329 
2330     // Simplify the output constraint.
2331     std::string OutputConstraint(S.getOutputConstraint(i));
2332     OutputConstraint = SimplifyConstraint(OutputConstraint.c_str() + 1,
2333                                           getTarget(), &OutputConstraintInfos);
2334 
2335     const Expr *OutExpr = S.getOutputExpr(i);
2336     OutExpr = OutExpr->IgnoreParenNoopCasts(getContext());
2337 
2338     std::string GCCReg;
2339     OutputConstraint = AddVariableConstraints(OutputConstraint, *OutExpr,
2340                                               getTarget(), CGM, S,
2341                                               Info.earlyClobber(),
2342                                               &GCCReg);
2343     // Give an error on multiple outputs to same physreg.
2344     if (!GCCReg.empty() && !PhysRegOutputs.insert(GCCReg).second)
2345       CGM.Error(S.getAsmLoc(), "multiple outputs to hard register: " + GCCReg);
2346 
2347     OutputConstraints.push_back(OutputConstraint);
2348     LValue Dest = EmitLValue(OutExpr);
2349     if (!Constraints.empty())
2350       Constraints += ',';
2351 
2352     // If this is a register output, then make the inline asm return it
2353     // by-value.  If this is a memory result, return the value by-reference.
2354     QualType QTy = OutExpr->getType();
2355     const bool IsScalarOrAggregate = hasScalarEvaluationKind(QTy) ||
2356                                      hasAggregateEvaluationKind(QTy);
2357     if (!Info.allowsMemory() && IsScalarOrAggregate) {
2358 
2359       Constraints += "=" + OutputConstraint;
2360       ResultRegQualTys.push_back(QTy);
2361       ResultRegDests.push_back(Dest);
2362 
2363       llvm::Type *Ty = ConvertTypeForMem(QTy);
2364       const bool RequiresCast = Info.allowsRegister() &&
2365           (getTargetHooks().isScalarizableAsmOperand(*this, Ty) ||
2366            Ty->isAggregateType());
2367 
2368       ResultTruncRegTypes.push_back(Ty);
2369       ResultTypeRequiresCast.push_back(RequiresCast);
2370 
2371       if (RequiresCast) {
2372         unsigned Size = getContext().getTypeSize(QTy);
2373         Ty = llvm::IntegerType::get(getLLVMContext(), Size);
2374       }
2375       ResultRegTypes.push_back(Ty);
2376       // If this output is tied to an input, and if the input is larger, then
2377       // we need to set the actual result type of the inline asm node to be the
2378       // same as the input type.
2379       if (Info.hasMatchingInput()) {
2380         unsigned InputNo;
2381         for (InputNo = 0; InputNo != S.getNumInputs(); ++InputNo) {
2382           TargetInfo::ConstraintInfo &Input = InputConstraintInfos[InputNo];
2383           if (Input.hasTiedOperand() && Input.getTiedOperand() == i)
2384             break;
2385         }
2386         assert(InputNo != S.getNumInputs() && "Didn't find matching input!");
2387 
2388         QualType InputTy = S.getInputExpr(InputNo)->getType();
2389         QualType OutputType = OutExpr->getType();
2390 
2391         uint64_t InputSize = getContext().getTypeSize(InputTy);
2392         if (getContext().getTypeSize(OutputType) < InputSize) {
2393           // Form the asm to return the value as a larger integer or fp type.
2394           ResultRegTypes.back() = ConvertType(InputTy);
2395         }
2396       }
2397       if (llvm::Type* AdjTy =
2398             getTargetHooks().adjustInlineAsmType(*this, OutputConstraint,
2399                                                  ResultRegTypes.back()))
2400         ResultRegTypes.back() = AdjTy;
2401       else {
2402         CGM.getDiags().Report(S.getAsmLoc(),
2403                               diag::err_asm_invalid_type_in_input)
2404             << OutExpr->getType() << OutputConstraint;
2405       }
2406 
2407       // Update largest vector width for any vector types.
2408       if (auto *VT = dyn_cast<llvm::VectorType>(ResultRegTypes.back()))
2409         LargestVectorWidth =
2410             std::max((uint64_t)LargestVectorWidth,
2411                      VT->getPrimitiveSizeInBits().getKnownMinSize());
2412     } else {
2413       llvm::Type *DestAddrTy = Dest.getAddress(*this).getType();
2414       llvm::Value *DestPtr = Dest.getPointer(*this);
2415       // Matrix types in memory are represented by arrays, but accessed through
2416       // vector pointers, with the alignment specified on the access operation.
2417       // For inline assembly, update pointer arguments to use vector pointers.
2418       // Otherwise there will be a mis-match if the matrix is also an
2419       // input-argument which is represented as vector.
2420       if (isa<MatrixType>(OutExpr->getType().getCanonicalType())) {
2421         DestAddrTy = llvm::PointerType::get(
2422             ConvertType(OutExpr->getType()),
2423             cast<llvm::PointerType>(DestAddrTy)->getAddressSpace());
2424         DestPtr = Builder.CreateBitCast(DestPtr, DestAddrTy);
2425       }
2426       ArgTypes.push_back(DestAddrTy);
2427       Args.push_back(DestPtr);
2428       Constraints += "=*";
2429       Constraints += OutputConstraint;
2430       ReadOnly = ReadNone = false;
2431     }
2432 
2433     if (Info.isReadWrite()) {
2434       InOutConstraints += ',';
2435 
2436       const Expr *InputExpr = S.getOutputExpr(i);
2437       llvm::Value *Arg = EmitAsmInputLValue(Info, Dest, InputExpr->getType(),
2438                                             InOutConstraints,
2439                                             InputExpr->getExprLoc());
2440 
2441       if (llvm::Type* AdjTy =
2442           getTargetHooks().adjustInlineAsmType(*this, OutputConstraint,
2443                                                Arg->getType()))
2444         Arg = Builder.CreateBitCast(Arg, AdjTy);
2445 
2446       // Update largest vector width for any vector types.
2447       if (auto *VT = dyn_cast<llvm::VectorType>(Arg->getType()))
2448         LargestVectorWidth =
2449             std::max((uint64_t)LargestVectorWidth,
2450                      VT->getPrimitiveSizeInBits().getKnownMinSize());
2451       // Only tie earlyclobber physregs.
2452       if (Info.allowsRegister() && (GCCReg.empty() || Info.earlyClobber()))
2453         InOutConstraints += llvm::utostr(i);
2454       else
2455         InOutConstraints += OutputConstraint;
2456 
2457       InOutArgTypes.push_back(Arg->getType());
2458       InOutArgs.push_back(Arg);
2459     }
2460   }
2461 
2462   // If this is a Microsoft-style asm blob, store the return registers (EAX:EDX)
2463   // to the return value slot. Only do this when returning in registers.
2464   if (isa<MSAsmStmt>(&S)) {
2465     const ABIArgInfo &RetAI = CurFnInfo->getReturnInfo();
2466     if (RetAI.isDirect() || RetAI.isExtend()) {
2467       // Make a fake lvalue for the return value slot.
2468       LValue ReturnSlot = MakeAddrLValue(ReturnValue, FnRetTy);
2469       CGM.getTargetCodeGenInfo().addReturnRegisterOutputs(
2470           *this, ReturnSlot, Constraints, ResultRegTypes, ResultTruncRegTypes,
2471           ResultRegDests, AsmString, S.getNumOutputs());
2472       SawAsmBlock = true;
2473     }
2474   }
2475 
2476   for (unsigned i = 0, e = S.getNumInputs(); i != e; i++) {
2477     const Expr *InputExpr = S.getInputExpr(i);
2478 
2479     TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
2480 
2481     if (Info.allowsMemory())
2482       ReadNone = false;
2483 
2484     if (!Constraints.empty())
2485       Constraints += ',';
2486 
2487     // Simplify the input constraint.
2488     std::string InputConstraint(S.getInputConstraint(i));
2489     InputConstraint = SimplifyConstraint(InputConstraint.c_str(), getTarget(),
2490                                          &OutputConstraintInfos);
2491 
2492     InputConstraint = AddVariableConstraints(
2493         InputConstraint, *InputExpr->IgnoreParenNoopCasts(getContext()),
2494         getTarget(), CGM, S, false /* No EarlyClobber */);
2495 
2496     std::string ReplaceConstraint (InputConstraint);
2497     llvm::Value *Arg = EmitAsmInput(Info, InputExpr, Constraints);
2498 
2499     // If this input argument is tied to a larger output result, extend the
2500     // input to be the same size as the output.  The LLVM backend wants to see
2501     // the input and output of a matching constraint be the same size.  Note
2502     // that GCC does not define what the top bits are here.  We use zext because
2503     // that is usually cheaper, but LLVM IR should really get an anyext someday.
2504     if (Info.hasTiedOperand()) {
2505       unsigned Output = Info.getTiedOperand();
2506       QualType OutputType = S.getOutputExpr(Output)->getType();
2507       QualType InputTy = InputExpr->getType();
2508 
2509       if (getContext().getTypeSize(OutputType) >
2510           getContext().getTypeSize(InputTy)) {
2511         // Use ptrtoint as appropriate so that we can do our extension.
2512         if (isa<llvm::PointerType>(Arg->getType()))
2513           Arg = Builder.CreatePtrToInt(Arg, IntPtrTy);
2514         llvm::Type *OutputTy = ConvertType(OutputType);
2515         if (isa<llvm::IntegerType>(OutputTy))
2516           Arg = Builder.CreateZExt(Arg, OutputTy);
2517         else if (isa<llvm::PointerType>(OutputTy))
2518           Arg = Builder.CreateZExt(Arg, IntPtrTy);
2519         else {
2520           assert(OutputTy->isFloatingPointTy() && "Unexpected output type");
2521           Arg = Builder.CreateFPExt(Arg, OutputTy);
2522         }
2523       }
2524       // Deal with the tied operands' constraint code in adjustInlineAsmType.
2525       ReplaceConstraint = OutputConstraints[Output];
2526     }
2527     if (llvm::Type* AdjTy =
2528           getTargetHooks().adjustInlineAsmType(*this, ReplaceConstraint,
2529                                                    Arg->getType()))
2530       Arg = Builder.CreateBitCast(Arg, AdjTy);
2531     else
2532       CGM.getDiags().Report(S.getAsmLoc(), diag::err_asm_invalid_type_in_input)
2533           << InputExpr->getType() << InputConstraint;
2534 
2535     // Update largest vector width for any vector types.
2536     if (auto *VT = dyn_cast<llvm::VectorType>(Arg->getType()))
2537       LargestVectorWidth =
2538           std::max((uint64_t)LargestVectorWidth,
2539                    VT->getPrimitiveSizeInBits().getKnownMinSize());
2540 
2541     ArgTypes.push_back(Arg->getType());
2542     Args.push_back(Arg);
2543     Constraints += InputConstraint;
2544   }
2545 
2546   // Labels
2547   SmallVector<llvm::BasicBlock *, 16> Transfer;
2548   llvm::BasicBlock *Fallthrough = nullptr;
2549   bool IsGCCAsmGoto = false;
2550   if (const auto *GS =  dyn_cast<GCCAsmStmt>(&S)) {
2551     IsGCCAsmGoto = GS->isAsmGoto();
2552     if (IsGCCAsmGoto) {
2553       for (const auto *E : GS->labels()) {
2554         JumpDest Dest = getJumpDestForLabel(E->getLabel());
2555         Transfer.push_back(Dest.getBlock());
2556         llvm::BlockAddress *BA =
2557             llvm::BlockAddress::get(CurFn, Dest.getBlock());
2558         Args.push_back(BA);
2559         ArgTypes.push_back(BA->getType());
2560         if (!Constraints.empty())
2561           Constraints += ',';
2562         Constraints += 'X';
2563       }
2564       Fallthrough = createBasicBlock("asm.fallthrough");
2565     }
2566   }
2567 
2568   // Append the "input" part of inout constraints last.
2569   for (unsigned i = 0, e = InOutArgs.size(); i != e; i++) {
2570     ArgTypes.push_back(InOutArgTypes[i]);
2571     Args.push_back(InOutArgs[i]);
2572   }
2573   Constraints += InOutConstraints;
2574 
2575   bool HasUnwindClobber = false;
2576 
2577   // Clobbers
2578   for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) {
2579     StringRef Clobber = S.getClobber(i);
2580 
2581     if (Clobber == "memory")
2582       ReadOnly = ReadNone = false;
2583     else if (Clobber == "unwind") {
2584       HasUnwindClobber = true;
2585       continue;
2586     } else if (Clobber != "cc") {
2587       Clobber = getTarget().getNormalizedGCCRegisterName(Clobber);
2588       if (CGM.getCodeGenOpts().StackClashProtector &&
2589           getTarget().isSPRegName(Clobber)) {
2590         CGM.getDiags().Report(S.getAsmLoc(),
2591                               diag::warn_stack_clash_protection_inline_asm);
2592       }
2593     }
2594 
2595     if (isa<MSAsmStmt>(&S)) {
2596       if (Clobber == "eax" || Clobber == "edx") {
2597         if (Constraints.find("=&A") != std::string::npos)
2598           continue;
2599         std::string::size_type position1 =
2600             Constraints.find("={" + Clobber.str() + "}");
2601         if (position1 != std::string::npos) {
2602           Constraints.insert(position1 + 1, "&");
2603           continue;
2604         }
2605         std::string::size_type position2 = Constraints.find("=A");
2606         if (position2 != std::string::npos) {
2607           Constraints.insert(position2 + 1, "&");
2608           continue;
2609         }
2610       }
2611     }
2612     if (!Constraints.empty())
2613       Constraints += ',';
2614 
2615     Constraints += "~{";
2616     Constraints += Clobber;
2617     Constraints += '}';
2618   }
2619 
2620   assert(!(HasUnwindClobber && IsGCCAsmGoto) &&
2621          "unwind clobber can't be used with asm goto");
2622 
2623   // Add machine specific clobbers
2624   std::string MachineClobbers = getTarget().getClobbers();
2625   if (!MachineClobbers.empty()) {
2626     if (!Constraints.empty())
2627       Constraints += ',';
2628     Constraints += MachineClobbers;
2629   }
2630 
2631   llvm::Type *ResultType;
2632   if (ResultRegTypes.empty())
2633     ResultType = VoidTy;
2634   else if (ResultRegTypes.size() == 1)
2635     ResultType = ResultRegTypes[0];
2636   else
2637     ResultType = llvm::StructType::get(getLLVMContext(), ResultRegTypes);
2638 
2639   llvm::FunctionType *FTy =
2640     llvm::FunctionType::get(ResultType, ArgTypes, false);
2641 
2642   bool HasSideEffect = S.isVolatile() || S.getNumOutputs() == 0;
2643   llvm::InlineAsm::AsmDialect AsmDialect = isa<MSAsmStmt>(&S) ?
2644     llvm::InlineAsm::AD_Intel : llvm::InlineAsm::AD_ATT;
2645   llvm::InlineAsm *IA = llvm::InlineAsm::get(
2646       FTy, AsmString, Constraints, HasSideEffect,
2647       /* IsAlignStack */ false, AsmDialect, HasUnwindClobber);
2648   std::vector<llvm::Value*> RegResults;
2649   if (IsGCCAsmGoto) {
2650     llvm::CallBrInst *Result =
2651         Builder.CreateCallBr(IA, Fallthrough, Transfer, Args);
2652     EmitBlock(Fallthrough);
2653     UpdateAsmCallInst(cast<llvm::CallBase>(*Result), HasSideEffect, false,
2654                       ReadOnly, ReadNone, InNoMergeAttributedStmt, S,
2655                       ResultRegTypes, *this, RegResults);
2656   } else if (HasUnwindClobber) {
2657     llvm::CallBase *Result = EmitCallOrInvoke(IA, Args, "");
2658     UpdateAsmCallInst(*Result, HasSideEffect, true, ReadOnly, ReadNone,
2659                       InNoMergeAttributedStmt, S, ResultRegTypes, *this,
2660                       RegResults);
2661   } else {
2662     llvm::CallInst *Result =
2663         Builder.CreateCall(IA, Args, getBundlesForFunclet(IA));
2664     UpdateAsmCallInst(cast<llvm::CallBase>(*Result), HasSideEffect, false,
2665                       ReadOnly, ReadNone, InNoMergeAttributedStmt, S,
2666                       ResultRegTypes, *this, RegResults);
2667   }
2668 
2669   assert(RegResults.size() == ResultRegTypes.size());
2670   assert(RegResults.size() == ResultTruncRegTypes.size());
2671   assert(RegResults.size() == ResultRegDests.size());
2672   // ResultRegDests can be also populated by addReturnRegisterOutputs() above,
2673   // in which case its size may grow.
2674   assert(ResultTypeRequiresCast.size() <= ResultRegDests.size());
2675   for (unsigned i = 0, e = RegResults.size(); i != e; ++i) {
2676     llvm::Value *Tmp = RegResults[i];
2677     llvm::Type *TruncTy = ResultTruncRegTypes[i];
2678 
2679     // If the result type of the LLVM IR asm doesn't match the result type of
2680     // the expression, do the conversion.
2681     if (ResultRegTypes[i] != ResultTruncRegTypes[i]) {
2682 
2683       // Truncate the integer result to the right size, note that TruncTy can be
2684       // a pointer.
2685       if (TruncTy->isFloatingPointTy())
2686         Tmp = Builder.CreateFPTrunc(Tmp, TruncTy);
2687       else if (TruncTy->isPointerTy() && Tmp->getType()->isIntegerTy()) {
2688         uint64_t ResSize = CGM.getDataLayout().getTypeSizeInBits(TruncTy);
2689         Tmp = Builder.CreateTrunc(Tmp,
2690                    llvm::IntegerType::get(getLLVMContext(), (unsigned)ResSize));
2691         Tmp = Builder.CreateIntToPtr(Tmp, TruncTy);
2692       } else if (Tmp->getType()->isPointerTy() && TruncTy->isIntegerTy()) {
2693         uint64_t TmpSize =CGM.getDataLayout().getTypeSizeInBits(Tmp->getType());
2694         Tmp = Builder.CreatePtrToInt(Tmp,
2695                    llvm::IntegerType::get(getLLVMContext(), (unsigned)TmpSize));
2696         Tmp = Builder.CreateTrunc(Tmp, TruncTy);
2697       } else if (TruncTy->isIntegerTy()) {
2698         Tmp = Builder.CreateZExtOrTrunc(Tmp, TruncTy);
2699       } else if (TruncTy->isVectorTy()) {
2700         Tmp = Builder.CreateBitCast(Tmp, TruncTy);
2701       }
2702     }
2703 
2704     LValue Dest = ResultRegDests[i];
2705     // ResultTypeRequiresCast elements correspond to the first
2706     // ResultTypeRequiresCast.size() elements of RegResults.
2707     if ((i < ResultTypeRequiresCast.size()) && ResultTypeRequiresCast[i]) {
2708       unsigned Size = getContext().getTypeSize(ResultRegQualTys[i]);
2709       Address A = Builder.CreateBitCast(Dest.getAddress(*this),
2710                                         ResultRegTypes[i]->getPointerTo());
2711       if (getTargetHooks().isScalarizableAsmOperand(*this, TruncTy)) {
2712         Builder.CreateStore(Tmp, A);
2713         continue;
2714       }
2715 
2716       QualType Ty = getContext().getIntTypeForBitwidth(Size, /*Signed*/ false);
2717       if (Ty.isNull()) {
2718         const Expr *OutExpr = S.getOutputExpr(i);
2719         CGM.Error(
2720             OutExpr->getExprLoc(),
2721             "impossible constraint in asm: can't store value into a register");
2722         return;
2723       }
2724       Dest = MakeAddrLValue(A, Ty);
2725     }
2726     EmitStoreThroughLValue(RValue::get(Tmp), Dest);
2727   }
2728 }
2729 
InitCapturedStruct(const CapturedStmt & S)2730 LValue CodeGenFunction::InitCapturedStruct(const CapturedStmt &S) {
2731   const RecordDecl *RD = S.getCapturedRecordDecl();
2732   QualType RecordTy = getContext().getRecordType(RD);
2733 
2734   // Initialize the captured struct.
2735   LValue SlotLV =
2736     MakeAddrLValue(CreateMemTemp(RecordTy, "agg.captured"), RecordTy);
2737 
2738   RecordDecl::field_iterator CurField = RD->field_begin();
2739   for (CapturedStmt::const_capture_init_iterator I = S.capture_init_begin(),
2740                                                  E = S.capture_init_end();
2741        I != E; ++I, ++CurField) {
2742     LValue LV = EmitLValueForFieldInitialization(SlotLV, *CurField);
2743     if (CurField->hasCapturedVLAType()) {
2744       EmitLambdaVLACapture(CurField->getCapturedVLAType(), LV);
2745     } else {
2746       EmitInitializerForField(*CurField, LV, *I);
2747     }
2748   }
2749 
2750   return SlotLV;
2751 }
2752 
2753 /// Generate an outlined function for the body of a CapturedStmt, store any
2754 /// captured variables into the captured struct, and call the outlined function.
2755 llvm::Function *
EmitCapturedStmt(const CapturedStmt & S,CapturedRegionKind K)2756 CodeGenFunction::EmitCapturedStmt(const CapturedStmt &S, CapturedRegionKind K) {
2757   LValue CapStruct = InitCapturedStruct(S);
2758 
2759   // Emit the CapturedDecl
2760   CodeGenFunction CGF(CGM, true);
2761   CGCapturedStmtRAII CapInfoRAII(CGF, new CGCapturedStmtInfo(S, K));
2762   llvm::Function *F = CGF.GenerateCapturedStmtFunction(S);
2763   delete CGF.CapturedStmtInfo;
2764 
2765   // Emit call to the helper function.
2766   EmitCallOrInvoke(F, CapStruct.getPointer(*this));
2767 
2768   return F;
2769 }
2770 
GenerateCapturedStmtArgument(const CapturedStmt & S)2771 Address CodeGenFunction::GenerateCapturedStmtArgument(const CapturedStmt &S) {
2772   LValue CapStruct = InitCapturedStruct(S);
2773   return CapStruct.getAddress(*this);
2774 }
2775 
2776 /// Creates the outlined function for a CapturedStmt.
2777 llvm::Function *
GenerateCapturedStmtFunction(const CapturedStmt & S)2778 CodeGenFunction::GenerateCapturedStmtFunction(const CapturedStmt &S) {
2779   assert(CapturedStmtInfo &&
2780     "CapturedStmtInfo should be set when generating the captured function");
2781   const CapturedDecl *CD = S.getCapturedDecl();
2782   const RecordDecl *RD = S.getCapturedRecordDecl();
2783   SourceLocation Loc = S.getBeginLoc();
2784   assert(CD->hasBody() && "missing CapturedDecl body");
2785 
2786   // Build the argument list.
2787   ASTContext &Ctx = CGM.getContext();
2788   FunctionArgList Args;
2789   Args.append(CD->param_begin(), CD->param_end());
2790 
2791   // Create the function declaration.
2792   const CGFunctionInfo &FuncInfo =
2793     CGM.getTypes().arrangeBuiltinFunctionDeclaration(Ctx.VoidTy, Args);
2794   llvm::FunctionType *FuncLLVMTy = CGM.getTypes().GetFunctionType(FuncInfo);
2795 
2796   llvm::Function *F =
2797     llvm::Function::Create(FuncLLVMTy, llvm::GlobalValue::InternalLinkage,
2798                            CapturedStmtInfo->getHelperName(), &CGM.getModule());
2799   CGM.SetInternalFunctionAttributes(CD, F, FuncInfo);
2800   if (CD->isNothrow())
2801     F->addFnAttr(llvm::Attribute::NoUnwind);
2802 
2803   // Generate the function.
2804   StartFunction(CD, Ctx.VoidTy, F, FuncInfo, Args, CD->getLocation(),
2805                 CD->getBody()->getBeginLoc());
2806   // Set the context parameter in CapturedStmtInfo.
2807   Address DeclPtr = GetAddrOfLocalVar(CD->getContextParam());
2808   CapturedStmtInfo->setContextValue(Builder.CreateLoad(DeclPtr));
2809 
2810   // Initialize variable-length arrays.
2811   LValue Base = MakeNaturalAlignAddrLValue(CapturedStmtInfo->getContextValue(),
2812                                            Ctx.getTagDeclType(RD));
2813   for (auto *FD : RD->fields()) {
2814     if (FD->hasCapturedVLAType()) {
2815       auto *ExprArg =
2816           EmitLoadOfLValue(EmitLValueForField(Base, FD), S.getBeginLoc())
2817               .getScalarVal();
2818       auto VAT = FD->getCapturedVLAType();
2819       VLASizeMap[VAT->getSizeExpr()] = ExprArg;
2820     }
2821   }
2822 
2823   // If 'this' is captured, load it into CXXThisValue.
2824   if (CapturedStmtInfo->isCXXThisExprCaptured()) {
2825     FieldDecl *FD = CapturedStmtInfo->getThisFieldDecl();
2826     LValue ThisLValue = EmitLValueForField(Base, FD);
2827     CXXThisValue = EmitLoadOfLValue(ThisLValue, Loc).getScalarVal();
2828   }
2829 
2830   PGO.assignRegionCounters(GlobalDecl(CD), F);
2831   CapturedStmtInfo->EmitBody(*this, CD->getBody());
2832   FinishFunction(CD->getBodyRBrace());
2833 
2834   return F;
2835 }
2836