clang  8.0.0svn
CGCoroutine.cpp
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1 //===----- CGCoroutine.cpp - Emit LLVM Code for C++ coroutines ------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This contains code dealing with C++ code generation of coroutines.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "CGCleanup.h"
15 #include "CodeGenFunction.h"
16 #include "llvm/ADT/ScopeExit.h"
17 #include "clang/AST/StmtCXX.h"
18 #include "clang/AST/StmtVisitor.h"
19 
20 using namespace clang;
21 using namespace CodeGen;
22 
23 using llvm::Value;
24 using llvm::BasicBlock;
25 
26 namespace {
27 enum class AwaitKind { Init, Normal, Yield, Final };
28 static constexpr llvm::StringLiteral AwaitKindStr[] = {"init", "await", "yield",
29  "final"};
30 }
31 
33  // What is the current await expression kind and how many
34  // await/yield expressions were encountered so far.
35  // These are used to generate pretty labels for await expressions in LLVM IR.
36  AwaitKind CurrentAwaitKind = AwaitKind::Init;
37  unsigned AwaitNum = 0;
38  unsigned YieldNum = 0;
39 
40  // How many co_return statements are in the coroutine. Used to decide whether
41  // we need to add co_return; equivalent at the end of the user authored body.
42  unsigned CoreturnCount = 0;
43 
44  // A branch to this block is emitted when coroutine needs to suspend.
45  llvm::BasicBlock *SuspendBB = nullptr;
46 
47  // The promise type's 'unhandled_exception' handler, if it defines one.
48  Stmt *ExceptionHandler = nullptr;
49 
50  // A temporary i1 alloca that stores whether 'await_resume' threw an
51  // exception. If it did, 'true' is stored in this variable, and the coroutine
52  // body must be skipped. If the promise type does not define an exception
53  // handler, this is null.
54  llvm::Value *ResumeEHVar = nullptr;
55 
56  // Stores the jump destination just before the coroutine memory is freed.
57  // This is the destination that every suspend point jumps to for the cleanup
58  // branch.
60 
61  // Stores the jump destination just before the final suspend. The co_return
62  // statements jumps to this point after calling return_xxx promise member.
64 
65  // Stores the llvm.coro.id emitted in the function so that we can supply it
66  // as the first argument to coro.begin, coro.alloc and coro.free intrinsics.
67  // Note: llvm.coro.id returns a token that cannot be directly expressed in a
68  // builtin.
69  llvm::CallInst *CoroId = nullptr;
70 
71  // Stores the llvm.coro.begin emitted in the function so that we can replace
72  // all coro.frame intrinsics with direct SSA value of coro.begin that returns
73  // the address of the coroutine frame of the current coroutine.
74  llvm::CallInst *CoroBegin = nullptr;
75 
76  // Stores the last emitted coro.free for the deallocate expressions, we use it
77  // to wrap dealloc code with if(auto mem = coro.free) dealloc(mem).
78  llvm::CallInst *LastCoroFree = nullptr;
79 
80  // If coro.id came from the builtin, remember the expression to give better
81  // diagnostic. If CoroIdExpr is nullptr, the coro.id was created by
82  // EmitCoroutineBody.
83  CallExpr const *CoroIdExpr = nullptr;
84 };
85 
86 // Defining these here allows to keep CGCoroData private to this file.
89 
92  llvm::CallInst *CoroId,
93  CallExpr const *CoroIdExpr = nullptr) {
94  if (CurCoro.Data) {
95  if (CurCoro.Data->CoroIdExpr)
96  CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
97  "only one __builtin_coro_id can be used in a function");
98  else if (CoroIdExpr)
99  CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
100  "__builtin_coro_id shall not be used in a C++ coroutine");
101  else
102  llvm_unreachable("EmitCoroutineBodyStatement called twice?");
103 
104  return;
105  }
106 
107  CurCoro.Data = std::unique_ptr<CGCoroData>(new CGCoroData);
108  CurCoro.Data->CoroId = CoroId;
109  CurCoro.Data->CoroIdExpr = CoroIdExpr;
110 }
111 
112 // Synthesize a pretty name for a suspend point.
113 static SmallString<32> buildSuspendPrefixStr(CGCoroData &Coro, AwaitKind Kind) {
114  unsigned No = 0;
115  switch (Kind) {
116  case AwaitKind::Init:
117  case AwaitKind::Final:
118  break;
119  case AwaitKind::Normal:
120  No = ++Coro.AwaitNum;
121  break;
122  case AwaitKind::Yield:
123  No = ++Coro.YieldNum;
124  break;
125  }
126  SmallString<32> Prefix(AwaitKindStr[static_cast<unsigned>(Kind)]);
127  if (No > 1) {
128  Twine(No).toVector(Prefix);
129  }
130  return Prefix;
131 }
132 
133 static bool memberCallExpressionCanThrow(const Expr *E) {
134  if (const auto *CE = dyn_cast<CXXMemberCallExpr>(E))
135  if (const auto *Proto =
136  CE->getMethodDecl()->getType()->getAs<FunctionProtoType>())
137  if (isNoexceptExceptionSpec(Proto->getExceptionSpecType()) &&
138  Proto->canThrow() == CT_Cannot)
139  return false;
140  return true;
141 }
142 
143 // Emit suspend expression which roughly looks like:
144 //
145 // auto && x = CommonExpr();
146 // if (!x.await_ready()) {
147 // llvm_coro_save();
148 // x.await_suspend(...); (*)
149 // llvm_coro_suspend(); (**)
150 // }
151 // x.await_resume();
152 //
153 // where the result of the entire expression is the result of x.await_resume()
154 //
155 // (*) If x.await_suspend return type is bool, it allows to veto a suspend:
156 // if (x.await_suspend(...))
157 // llvm_coro_suspend();
158 //
159 // (**) llvm_coro_suspend() encodes three possible continuations as
160 // a switch instruction:
161 //
162 // %where-to = call i8 @llvm.coro.suspend(...)
163 // switch i8 %where-to, label %coro.ret [ ; jump to epilogue to suspend
164 // i8 0, label %yield.ready ; go here when resumed
165 // i8 1, label %yield.cleanup ; go here when destroyed
166 // ]
167 //
168 // See llvm's docs/Coroutines.rst for more details.
169 //
170 namespace {
171  struct LValueOrRValue {
172  LValue LV;
173  RValue RV;
174  };
175 }
176 static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Coro,
177  CoroutineSuspendExpr const &S,
178  AwaitKind Kind, AggValueSlot aggSlot,
179  bool ignoreResult, bool forLValue) {
180  auto *E = S.getCommonExpr();
181 
182  auto Binder =
184  auto UnbindOnExit = llvm::make_scope_exit([&] { Binder.unbind(CGF); });
185 
186  auto Prefix = buildSuspendPrefixStr(Coro, Kind);
187  BasicBlock *ReadyBlock = CGF.createBasicBlock(Prefix + Twine(".ready"));
188  BasicBlock *SuspendBlock = CGF.createBasicBlock(Prefix + Twine(".suspend"));
189  BasicBlock *CleanupBlock = CGF.createBasicBlock(Prefix + Twine(".cleanup"));
190 
191  // If expression is ready, no need to suspend.
192  CGF.EmitBranchOnBoolExpr(S.getReadyExpr(), ReadyBlock, SuspendBlock, 0);
193 
194  // Otherwise, emit suspend logic.
195  CGF.EmitBlock(SuspendBlock);
196 
197  auto &Builder = CGF.Builder;
198  llvm::Function *CoroSave = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_save);
199  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.CGM.Int8PtrTy);
200  auto *SaveCall = Builder.CreateCall(CoroSave, {NullPtr});
201 
202  auto *SuspendRet = CGF.EmitScalarExpr(S.getSuspendExpr());
203  if (SuspendRet != nullptr && SuspendRet->getType()->isIntegerTy(1)) {
204  // Veto suspension if requested by bool returning await_suspend.
205  BasicBlock *RealSuspendBlock =
206  CGF.createBasicBlock(Prefix + Twine(".suspend.bool"));
207  CGF.Builder.CreateCondBr(SuspendRet, RealSuspendBlock, ReadyBlock);
208  SuspendBlock = RealSuspendBlock;
209  CGF.EmitBlock(RealSuspendBlock);
210  }
211 
212  // Emit the suspend point.
213  const bool IsFinalSuspend = (Kind == AwaitKind::Final);
214  llvm::Function *CoroSuspend =
215  CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_suspend);
216  auto *SuspendResult = Builder.CreateCall(
217  CoroSuspend, {SaveCall, Builder.getInt1(IsFinalSuspend)});
218 
219  // Create a switch capturing three possible continuations.
220  auto *Switch = Builder.CreateSwitch(SuspendResult, Coro.SuspendBB, 2);
221  Switch->addCase(Builder.getInt8(0), ReadyBlock);
222  Switch->addCase(Builder.getInt8(1), CleanupBlock);
223 
224  // Emit cleanup for this suspend point.
225  CGF.EmitBlock(CleanupBlock);
227 
228  // Emit await_resume expression.
229  CGF.EmitBlock(ReadyBlock);
230 
231  // Exception handling requires additional IR. If the 'await_resume' function
232  // is marked as 'noexcept', we avoid generating this additional IR.
233  CXXTryStmt *TryStmt = nullptr;
234  if (Coro.ExceptionHandler && Kind == AwaitKind::Init &&
236  Coro.ResumeEHVar =
237  CGF.CreateTempAlloca(Builder.getInt1Ty(), Prefix + Twine("resume.eh"));
238  Builder.CreateFlagStore(true, Coro.ResumeEHVar);
239 
240  auto Loc = S.getResumeExpr()->getExprLoc();
241  auto *Catch = new (CGF.getContext())
242  CXXCatchStmt(Loc, /*exDecl=*/nullptr, Coro.ExceptionHandler);
243  auto *TryBody =
244  CompoundStmt::Create(CGF.getContext(), S.getResumeExpr(), Loc, Loc);
245  TryStmt = CXXTryStmt::Create(CGF.getContext(), Loc, TryBody, Catch);
246  CGF.EnterCXXTryStmt(*TryStmt);
247  }
248 
249  LValueOrRValue Res;
250  if (forLValue)
251  Res.LV = CGF.EmitLValue(S.getResumeExpr());
252  else
253  Res.RV = CGF.EmitAnyExpr(S.getResumeExpr(), aggSlot, ignoreResult);
254 
255  if (TryStmt) {
256  Builder.CreateFlagStore(false, Coro.ResumeEHVar);
257  CGF.ExitCXXTryStmt(*TryStmt);
258  }
259 
260  return Res;
261 }
262 
264  AggValueSlot aggSlot,
265  bool ignoreResult) {
266  return emitSuspendExpression(*this, *CurCoro.Data, E,
267  CurCoro.Data->CurrentAwaitKind, aggSlot,
268  ignoreResult, /*forLValue*/false).RV;
269 }
271  AggValueSlot aggSlot,
272  bool ignoreResult) {
273  return emitSuspendExpression(*this, *CurCoro.Data, E, AwaitKind::Yield,
274  aggSlot, ignoreResult, /*forLValue*/false).RV;
275 }
276 
278  ++CurCoro.Data->CoreturnCount;
279  const Expr *RV = S.getOperand();
280  if (RV && RV->getType()->isVoidType()) {
281  // Make sure to evaluate the expression of a co_return with a void
282  // expression for side effects.
283  RunCleanupsScope cleanupScope(*this);
284  EmitIgnoredExpr(RV);
285  }
286  EmitStmt(S.getPromiseCall());
287  EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
288 }
289 
290 
291 #ifndef NDEBUG
293  const CoroutineSuspendExpr *E) {
294  const auto *RE = E->getResumeExpr();
295  // Is it possible for RE to be a CXXBindTemporaryExpr wrapping
296  // a MemberCallExpr?
297  assert(isa<CallExpr>(RE) && "unexpected suspend expression type");
298  return cast<CallExpr>(RE)->getCallReturnType(Ctx);
299 }
300 #endif
301 
302 LValue
304  assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
305  "Can't have a scalar return unless the return type is a "
306  "reference type!");
307  return emitSuspendExpression(*this, *CurCoro.Data, *E,
308  CurCoro.Data->CurrentAwaitKind, AggValueSlot::ignored(),
309  /*ignoreResult*/false, /*forLValue*/true).LV;
310 }
311 
312 LValue
314  assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
315  "Can't have a scalar return unless the return type is a "
316  "reference type!");
317  return emitSuspendExpression(*this, *CurCoro.Data, *E,
318  AwaitKind::Yield, AggValueSlot::ignored(),
319  /*ignoreResult*/false, /*forLValue*/true).LV;
320 }
321 
322 // Hunts for the parameter reference in the parameter copy/move declaration.
323 namespace {
324 struct GetParamRef : public StmtVisitor<GetParamRef> {
325 public:
326  DeclRefExpr *Expr = nullptr;
327  GetParamRef() {}
328  void VisitDeclRefExpr(DeclRefExpr *E) {
329  assert(Expr == nullptr && "multilple declref in param move");
330  Expr = E;
331  }
332  void VisitStmt(Stmt *S) {
333  for (auto *C : S->children()) {
334  if (C)
335  Visit(C);
336  }
337  }
338 };
339 }
340 
341 // This class replaces references to parameters to their copies by changing
342 // the addresses in CGF.LocalDeclMap and restoring back the original values in
343 // its destructor.
344 
345 namespace {
346  struct ParamReferenceReplacerRAII {
347  CodeGenFunction::DeclMapTy SavedLocals;
348  CodeGenFunction::DeclMapTy& LocalDeclMap;
349 
350  ParamReferenceReplacerRAII(CodeGenFunction::DeclMapTy &LocalDeclMap)
351  : LocalDeclMap(LocalDeclMap) {}
352 
353  void addCopy(DeclStmt const *PM) {
354  // Figure out what param it refers to.
355 
356  assert(PM->isSingleDecl());
357  VarDecl const*VD = static_cast<VarDecl const*>(PM->getSingleDecl());
358  Expr const *InitExpr = VD->getInit();
359  GetParamRef Visitor;
360  Visitor.Visit(const_cast<Expr*>(InitExpr));
361  assert(Visitor.Expr);
362  DeclRefExpr *DREOrig = Visitor.Expr;
363  auto *PD = DREOrig->getDecl();
364 
365  auto it = LocalDeclMap.find(PD);
366  assert(it != LocalDeclMap.end() && "parameter is not found");
367  SavedLocals.insert({ PD, it->second });
368 
369  auto copyIt = LocalDeclMap.find(VD);
370  assert(copyIt != LocalDeclMap.end() && "parameter copy is not found");
371  it->second = copyIt->getSecond();
372  }
373 
374  ~ParamReferenceReplacerRAII() {
375  for (auto&& SavedLocal : SavedLocals) {
376  LocalDeclMap.insert({SavedLocal.first, SavedLocal.second});
377  }
378  }
379  };
380 }
381 
382 // For WinEH exception representation backend needs to know what funclet coro.end
383 // belongs to. That information is passed in a funclet bundle.
387 
388  if (llvm::Instruction *EHPad = CGF.CurrentFuncletPad)
389  BundleList.emplace_back("funclet", EHPad);
390 
391  return BundleList;
392 }
393 
394 namespace {
395 // We will insert coro.end to cut any of the destructors for objects that
396 // do not need to be destroyed once the coroutine is resumed.
397 // See llvm/docs/Coroutines.rst for more details about coro.end.
398 struct CallCoroEnd final : public EHScopeStack::Cleanup {
399  void Emit(CodeGenFunction &CGF, Flags flags) override {
400  auto &CGM = CGF.CGM;
401  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
402  llvm::Function *CoroEndFn = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
403  // See if we have a funclet bundle to associate coro.end with. (WinEH)
404  auto Bundles = getBundlesForCoroEnd(CGF);
405  auto *CoroEnd = CGF.Builder.CreateCall(
406  CoroEndFn, {NullPtr, CGF.Builder.getTrue()}, Bundles);
407  if (Bundles.empty()) {
408  // Otherwise, (landingpad model), create a conditional branch that leads
409  // either to a cleanup block or a block with EH resume instruction.
410  auto *ResumeBB = CGF.getEHResumeBlock(/*cleanup=*/true);
411  auto *CleanupContBB = CGF.createBasicBlock("cleanup.cont");
412  CGF.Builder.CreateCondBr(CoroEnd, ResumeBB, CleanupContBB);
413  CGF.EmitBlock(CleanupContBB);
414  }
415  }
416 };
417 }
418 
419 namespace {
420 // Make sure to call coro.delete on scope exit.
421 struct CallCoroDelete final : public EHScopeStack::Cleanup {
422  Stmt *Deallocate;
423 
424  // Emit "if (coro.free(CoroId, CoroBegin)) Deallocate;"
425 
426  // Note: That deallocation will be emitted twice: once for a normal exit and
427  // once for exceptional exit. This usage is safe because Deallocate does not
428  // contain any declarations. The SubStmtBuilder::makeNewAndDeleteExpr()
429  // builds a single call to a deallocation function which is safe to emit
430  // multiple times.
431  void Emit(CodeGenFunction &CGF, Flags) override {
432  // Remember the current point, as we are going to emit deallocation code
433  // first to get to coro.free instruction that is an argument to a delete
434  // call.
435  BasicBlock *SaveInsertBlock = CGF.Builder.GetInsertBlock();
436 
437  auto *FreeBB = CGF.createBasicBlock("coro.free");
438  CGF.EmitBlock(FreeBB);
439  CGF.EmitStmt(Deallocate);
440 
441  auto *AfterFreeBB = CGF.createBasicBlock("after.coro.free");
442  CGF.EmitBlock(AfterFreeBB);
443 
444  // We should have captured coro.free from the emission of deallocate.
445  auto *CoroFree = CGF.CurCoro.Data->LastCoroFree;
446  if (!CoroFree) {
447  CGF.CGM.Error(Deallocate->getBeginLoc(),
448  "Deallocation expressoin does not refer to coro.free");
449  return;
450  }
451 
452  // Get back to the block we were originally and move coro.free there.
453  auto *InsertPt = SaveInsertBlock->getTerminator();
454  CoroFree->moveBefore(InsertPt);
455  CGF.Builder.SetInsertPoint(InsertPt);
456 
457  // Add if (auto *mem = coro.free) Deallocate;
458  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
459  auto *Cond = CGF.Builder.CreateICmpNE(CoroFree, NullPtr);
460  CGF.Builder.CreateCondBr(Cond, FreeBB, AfterFreeBB);
461 
462  // No longer need old terminator.
463  InsertPt->eraseFromParent();
464  CGF.Builder.SetInsertPoint(AfterFreeBB);
465  }
466  explicit CallCoroDelete(Stmt *DeallocStmt) : Deallocate(DeallocStmt) {}
467 };
468 }
469 
470 namespace {
471 struct GetReturnObjectManager {
472  CodeGenFunction &CGF;
473  CGBuilderTy &Builder;
474  const CoroutineBodyStmt &S;
475 
476  Address GroActiveFlag;
478 
479  GetReturnObjectManager(CodeGenFunction &CGF, const CoroutineBodyStmt &S)
480  : CGF(CGF), Builder(CGF.Builder), S(S), GroActiveFlag(Address::invalid()),
482 
483  // The gro variable has to outlive coroutine frame and coroutine promise, but,
484  // it can only be initialized after coroutine promise was created, thus, we
485  // split its emission in two parts. EmitGroAlloca emits an alloca and sets up
486  // cleanups. Later when coroutine promise is available we initialize the gro
487  // and sets the flag that the cleanup is now active.
488 
489  void EmitGroAlloca() {
490  auto *GroDeclStmt = dyn_cast<DeclStmt>(S.getResultDecl());
491  if (!GroDeclStmt) {
492  // If get_return_object returns void, no need to do an alloca.
493  return;
494  }
495 
496  auto *GroVarDecl = cast<VarDecl>(GroDeclStmt->getSingleDecl());
497 
498  // Set GRO flag that it is not initialized yet
499  GroActiveFlag =
500  CGF.CreateTempAlloca(Builder.getInt1Ty(), CharUnits::One(), "gro.active");
501  Builder.CreateStore(Builder.getFalse(), GroActiveFlag);
502 
503  GroEmission = CGF.EmitAutoVarAlloca(*GroVarDecl);
504 
505  // Remember the top of EHStack before emitting the cleanup.
506  auto old_top = CGF.EHStack.stable_begin();
507  CGF.EmitAutoVarCleanups(GroEmission);
508  auto top = CGF.EHStack.stable_begin();
509 
510  // Make the cleanup conditional on gro.active
511  for (auto b = CGF.EHStack.find(top), e = CGF.EHStack.find(old_top);
512  b != e; b++) {
513  if (auto *Cleanup = dyn_cast<EHCleanupScope>(&*b)) {
514  assert(!Cleanup->hasActiveFlag() && "cleanup already has active flag?");
515  Cleanup->setActiveFlag(GroActiveFlag);
516  Cleanup->setTestFlagInEHCleanup();
517  Cleanup->setTestFlagInNormalCleanup();
518  }
519  }
520  }
521 
522  void EmitGroInit() {
523  if (!GroActiveFlag.isValid()) {
524  // No Gro variable was allocated. Simply emit the call to
525  // get_return_object.
526  CGF.EmitStmt(S.getResultDecl());
527  return;
528  }
529 
530  CGF.EmitAutoVarInit(GroEmission);
531  Builder.CreateStore(Builder.getTrue(), GroActiveFlag);
532  }
533 };
534 }
535 
537  const CoroutineBodyStmt &S, Stmt *Body) {
538  CGF.EmitStmt(Body);
539  const bool CanFallthrough = CGF.Builder.GetInsertBlock();
540  if (CanFallthrough)
541  if (Stmt *OnFallthrough = S.getFallthroughHandler())
542  CGF.EmitStmt(OnFallthrough);
543 }
544 
546  auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
547  auto &TI = CGM.getContext().getTargetInfo();
548  unsigned NewAlign = TI.getNewAlign() / TI.getCharWidth();
549 
550  auto *EntryBB = Builder.GetInsertBlock();
551  auto *AllocBB = createBasicBlock("coro.alloc");
552  auto *InitBB = createBasicBlock("coro.init");
553  auto *FinalBB = createBasicBlock("coro.final");
554  auto *RetBB = createBasicBlock("coro.ret");
555 
556  auto *CoroId = Builder.CreateCall(
557  CGM.getIntrinsic(llvm::Intrinsic::coro_id),
558  {Builder.getInt32(NewAlign), NullPtr, NullPtr, NullPtr});
559  createCoroData(*this, CurCoro, CoroId);
560  CurCoro.Data->SuspendBB = RetBB;
561 
562  // Backend is allowed to elide memory allocations, to help it, emit
563  // auto mem = coro.alloc() ? 0 : ... allocation code ...;
564  auto *CoroAlloc = Builder.CreateCall(
565  CGM.getIntrinsic(llvm::Intrinsic::coro_alloc), {CoroId});
566 
567  Builder.CreateCondBr(CoroAlloc, AllocBB, InitBB);
568 
569  EmitBlock(AllocBB);
570  auto *AllocateCall = EmitScalarExpr(S.getAllocate());
571  auto *AllocOrInvokeContBB = Builder.GetInsertBlock();
572 
573  // Handle allocation failure if 'ReturnStmtOnAllocFailure' was provided.
574  if (auto *RetOnAllocFailure = S.getReturnStmtOnAllocFailure()) {
575  auto *RetOnFailureBB = createBasicBlock("coro.ret.on.failure");
576 
577  // See if allocation was successful.
578  auto *NullPtr = llvm::ConstantPointerNull::get(Int8PtrTy);
579  auto *Cond = Builder.CreateICmpNE(AllocateCall, NullPtr);
580  Builder.CreateCondBr(Cond, InitBB, RetOnFailureBB);
581 
582  // If not, return OnAllocFailure object.
583  EmitBlock(RetOnFailureBB);
584  EmitStmt(RetOnAllocFailure);
585  }
586  else {
587  Builder.CreateBr(InitBB);
588  }
589 
590  EmitBlock(InitBB);
591 
592  // Pass the result of the allocation to coro.begin.
593  auto *Phi = Builder.CreatePHI(VoidPtrTy, 2);
594  Phi->addIncoming(NullPtr, EntryBB);
595  Phi->addIncoming(AllocateCall, AllocOrInvokeContBB);
596  auto *CoroBegin = Builder.CreateCall(
597  CGM.getIntrinsic(llvm::Intrinsic::coro_begin), {CoroId, Phi});
598  CurCoro.Data->CoroBegin = CoroBegin;
599 
600  GetReturnObjectManager GroManager(*this, S);
601  GroManager.EmitGroAlloca();
602 
603  CurCoro.Data->CleanupJD = getJumpDestInCurrentScope(RetBB);
604  {
605  ParamReferenceReplacerRAII ParamReplacer(LocalDeclMap);
606  CodeGenFunction::RunCleanupsScope ResumeScope(*this);
607  EHStack.pushCleanup<CallCoroDelete>(NormalAndEHCleanup, S.getDeallocate());
608 
609  // Create parameter copies. We do it before creating a promise, since an
610  // evolution of coroutine TS may allow promise constructor to observe
611  // parameter copies.
612  for (auto *PM : S.getParamMoves()) {
613  EmitStmt(PM);
614  ParamReplacer.addCopy(cast<DeclStmt>(PM));
615  // TODO: if(CoroParam(...)) need to surround ctor and dtor
616  // for the copy, so that llvm can elide it if the copy is
617  // not needed.
618  }
619 
620  EmitStmt(S.getPromiseDeclStmt());
621 
622  Address PromiseAddr = GetAddrOfLocalVar(S.getPromiseDecl());
623  auto *PromiseAddrVoidPtr =
624  new llvm::BitCastInst(PromiseAddr.getPointer(), VoidPtrTy, "", CoroId);
625  // Update CoroId to refer to the promise. We could not do it earlier because
626  // promise local variable was not emitted yet.
627  CoroId->setArgOperand(1, PromiseAddrVoidPtr);
628 
629  // Now we have the promise, initialize the GRO
630  GroManager.EmitGroInit();
631 
632  EHStack.pushCleanup<CallCoroEnd>(EHCleanup);
633 
634  CurCoro.Data->CurrentAwaitKind = AwaitKind::Init;
635  CurCoro.Data->ExceptionHandler = S.getExceptionHandler();
636  EmitStmt(S.getInitSuspendStmt());
637  CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
638 
639  CurCoro.Data->CurrentAwaitKind = AwaitKind::Normal;
640 
641  if (CurCoro.Data->ExceptionHandler) {
642  // If we generated IR to record whether an exception was thrown from
643  // 'await_resume', then use that IR to determine whether the coroutine
644  // body should be skipped.
645  // If we didn't generate the IR (perhaps because 'await_resume' was marked
646  // as 'noexcept'), then we skip this check.
647  BasicBlock *ContBB = nullptr;
648  if (CurCoro.Data->ResumeEHVar) {
649  BasicBlock *BodyBB = createBasicBlock("coro.resumed.body");
650  ContBB = createBasicBlock("coro.resumed.cont");
651  Value *SkipBody = Builder.CreateFlagLoad(CurCoro.Data->ResumeEHVar,
652  "coro.resumed.eh");
653  Builder.CreateCondBr(SkipBody, ContBB, BodyBB);
654  EmitBlock(BodyBB);
655  }
656 
657  auto Loc = S.getBeginLoc();
658  CXXCatchStmt Catch(Loc, /*exDecl=*/nullptr,
659  CurCoro.Data->ExceptionHandler);
660  auto *TryStmt =
661  CXXTryStmt::Create(getContext(), Loc, S.getBody(), &Catch);
662 
663  EnterCXXTryStmt(*TryStmt);
664  emitBodyAndFallthrough(*this, S, TryStmt->getTryBlock());
665  ExitCXXTryStmt(*TryStmt);
666 
667  if (ContBB)
668  EmitBlock(ContBB);
669  }
670  else {
671  emitBodyAndFallthrough(*this, S, S.getBody());
672  }
673 
674  // See if we need to generate final suspend.
675  const bool CanFallthrough = Builder.GetInsertBlock();
676  const bool HasCoreturns = CurCoro.Data->CoreturnCount > 0;
677  if (CanFallthrough || HasCoreturns) {
678  EmitBlock(FinalBB);
679  CurCoro.Data->CurrentAwaitKind = AwaitKind::Final;
680  EmitStmt(S.getFinalSuspendStmt());
681  } else {
682  // We don't need FinalBB. Emit it to make sure the block is deleted.
683  EmitBlock(FinalBB, /*IsFinished=*/true);
684  }
685  }
686 
687  EmitBlock(RetBB);
688  // Emit coro.end before getReturnStmt (and parameter destructors), since
689  // resume and destroy parts of the coroutine should not include them.
690  llvm::Function *CoroEnd = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
691  Builder.CreateCall(CoroEnd, {NullPtr, Builder.getFalse()});
692 
693  if (Stmt *Ret = S.getReturnStmt())
694  EmitStmt(Ret);
695 }
696 
697 // Emit coroutine intrinsic and patch up arguments of the token type.
699  unsigned int IID) {
701  switch (IID) {
702  default:
703  break;
704  // The coro.frame builtin is replaced with an SSA value of the coro.begin
705  // intrinsic.
706  case llvm::Intrinsic::coro_frame: {
707  if (CurCoro.Data && CurCoro.Data->CoroBegin) {
708  return RValue::get(CurCoro.Data->CoroBegin);
709  }
710  CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_begin "
711  "has been used earlier in this function");
712  auto NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
713  return RValue::get(NullPtr);
714  }
715  // The following three intrinsics take a token parameter referring to a token
716  // returned by earlier call to @llvm.coro.id. Since we cannot represent it in
717  // builtins, we patch it up here.
718  case llvm::Intrinsic::coro_alloc:
719  case llvm::Intrinsic::coro_begin:
720  case llvm::Intrinsic::coro_free: {
721  if (CurCoro.Data && CurCoro.Data->CoroId) {
722  Args.push_back(CurCoro.Data->CoroId);
723  break;
724  }
725  CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_id has"
726  " been used earlier in this function");
727  // Fallthrough to the next case to add TokenNone as the first argument.
728  LLVM_FALLTHROUGH;
729  }
730  // @llvm.coro.suspend takes a token parameter. Add token 'none' as the first
731  // argument.
732  case llvm::Intrinsic::coro_suspend:
733  Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
734  break;
735  }
736  for (auto &Arg : E->arguments())
737  Args.push_back(EmitScalarExpr(Arg));
738 
739  llvm::Value *F = CGM.getIntrinsic(IID);
740  llvm::CallInst *Call = Builder.CreateCall(F, Args);
741 
742  // Note: The following code is to enable to emit coro.id and coro.begin by
743  // hand to experiment with coroutines in C.
744  // If we see @llvm.coro.id remember it in the CoroData. We will update
745  // coro.alloc, coro.begin and coro.free intrinsics to refer to it.
746  if (IID == llvm::Intrinsic::coro_id) {
747  createCoroData(*this, CurCoro, Call, E);
748  }
749  else if (IID == llvm::Intrinsic::coro_begin) {
750  if (CurCoro.Data)
751  CurCoro.Data->CoroBegin = Call;
752  }
753  else if (IID == llvm::Intrinsic::coro_free) {
754  // Remember the last coro_free as we need it to build the conditional
755  // deletion of the coroutine frame.
756  if (CurCoro.Data)
757  CurCoro.Data->LastCoroFree = Call;
758  }
759  return RValue::get(Call);
760 }
Expr * getReadyExpr() const
Definition: ExprCXX.h:4311
void EmitCoroutineBody(const CoroutineBodyStmt &S)
A (possibly-)qualified type.
Definition: Type.h:642
void EmitBranchOnBoolExpr(const Expr *Cond, llvm::BasicBlock *TrueBlock, llvm::BasicBlock *FalseBlock, uint64_t TrueCount)
EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g.
RValue EmitCoyieldExpr(const CoyieldExpr &E, AggValueSlot aggSlot=AggValueSlot::ignored(), bool ignoreResult=false)
Represents a &#39;co_return&#39; statement in the C++ Coroutines TS.
Definition: StmtCXX.h:432
Stmt - This represents one statement.
Definition: Stmt.h:66
static bool memberCallExpressionCanThrow(const Expr *E)
RValue EmitCoawaitExpr(const CoawaitExpr &E, AggValueSlot aggSlot=AggValueSlot::ignored(), bool ignoreResult=false)
Stmt * getPromiseDeclStmt() const
Definition: StmtCXX.h:364
iterator find(stable_iterator save) const
Turn a stable reference to a scope depth into a unstable pointer to the EH stack. ...
Definition: CGCleanup.h:591
stable_iterator stable_begin() const
Create a stable reference to the top of the EH stack.
Definition: EHScopeStack.h:379
Stmt * getExceptionHandler() const
Definition: StmtCXX.h:378
Expr * getDeallocate() const
Definition: StmtCXX.h:388
Represents a variable declaration or definition.
Definition: Decl.h:812
Stmt * getResultDecl() const
Definition: StmtCXX.h:394
A jump destination is an abstract label, branching to which may require a jump out through normal cle...
bool isNoexceptExceptionSpec(ExceptionSpecificationType ESpecType)
CodeGenFunction - This class organizes the per-function state that is used while generating LLVM code...
Holds long-lived AST nodes (such as types and decls) that can be referred to throughout the semantic ...
Definition: ASTContext.h:154
VarDecl * getPromiseDecl() const
Definition: StmtCXX.h:367
LValue EmitCoyieldLValue(const CoyieldExpr *E)
Denotes a cleanup that should run when a scope is exited using exceptional control flow (a throw stat...
Definition: EHScopeStack.h:81
RValue EmitAnyExpr(const Expr *E, AggValueSlot aggSlot=AggValueSlot::ignored(), bool ignoreResult=false)
EmitAnyExpr - Emit code to compute the specified expression which can have any type.
Definition: CGExpr.cpp:194
ArrayRef< Stmt const * > getParamMoves() const
Definition: StmtCXX.h:399
child_range children()
Definition: Stmt.cpp:229
static CompoundStmt * Create(const ASTContext &C, ArrayRef< Stmt *> Stmts, SourceLocation LB, SourceLocation RB)
Definition: Stmt.cpp:326
llvm::BasicBlock * createBasicBlock(const Twine &name="", llvm::Function *parent=nullptr, llvm::BasicBlock *before=nullptr)
createBasicBlock - Create an LLVM basic block.
OpaqueValueExpr * getOpaqueValue() const
getOpaqueValue - Return the opaque value placeholder.
Definition: ExprCXX.h:4309
Expr * getCommonExpr() const
Definition: ExprCXX.h:4304
llvm::AllocaInst * CreateTempAlloca(llvm::Type *Ty, const Twine &Name="tmp", llvm::Value *ArraySize=nullptr)
CreateTempAlloca - This creates an alloca and inserts it into the entry block if ArraySize is nullptr...
Definition: CGExpr.cpp:106
Stmt * getReturnStmt() const
Definition: StmtCXX.h:395
static QualType getCoroutineSuspendExprReturnType(const ASTContext &Ctx, const CoroutineSuspendExpr *E)
bool isValid() const
Definition: Address.h:36
static CharUnits One()
One - Construct a CharUnits quantity of one.
Definition: CharUnits.h:58
AutoVarEmission EmitAutoVarAlloca(const VarDecl &var)
EmitAutoVarAlloca - Emit the alloca and debug information for a local variable.
Definition: CGDecl.cpp:1119
Represents a prototype with parameter type info, e.g.
Definition: Type.h:3550
RValue - This trivial value class is used to represent the result of an expression that is evaluated...
Definition: CGValue.h:39
static SmallVector< llvm::OperandBundleDef, 1 > getBundlesForCoroEnd(CodeGenFunction &CGF)
static SmallString< 32 > buildSuspendPrefixStr(CGCoroData &Coro, AwaitKind Kind)
This represents one expression.
Definition: Expr.h:105
void EmitAutoVarInit(const AutoVarEmission &emission)
Definition: CGDecl.cpp:1399
static Address invalid()
Definition: Address.h:35
Enters a new scope for capturing cleanups, all of which will be executed once the scope is exited...
CXXTryStmt - A C++ try block, including all handlers.
Definition: StmtCXX.h:65
QualType getType() const
Definition: Expr.h:127
ValueDecl * getDecl()
Definition: Expr.h:1056
CodeGenFunction::JumpDest FinalJD
Definition: CGCoroutine.cpp:63
Kind
static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Coro, CoroutineSuspendExpr const &S, AwaitKind Kind, AggValueSlot aggSlot, bool ignoreResult, bool forLValue)
RValue EmitCoroutineIntrinsic(const CallExpr *E, unsigned int IID)
DeclStmt - Adaptor class for mixing declarations with statements and expressions. ...
Definition: Stmt.h:505
An aggregate value slot.
Definition: CGValue.h:437
SourceLocation getBeginLoc() const LLVM_READONLY
Definition: StmtCXX.h:403
CodeGenFunction::JumpDest CleanupJD
Definition: CGCoroutine.cpp:59
void EmitStmt(const Stmt *S, ArrayRef< const Attr *> Attrs=None)
EmitStmt - Emit the code for the statement.
Definition: CGStmt.cpp:48
StmtVisitor - This class implements a simple visitor for Stmt subclasses.
Definition: StmtVisitor.h:186
Expr * getSuspendExpr() const
Definition: ExprCXX.h:4315
arg_range arguments()
Definition: Expr.h:2379
An aligned address.
Definition: Address.h:25
llvm::BasicBlock * SuspendBB
Definition: CGCoroutine.cpp:45
llvm::BasicBlock * getEHResumeBlock(bool isCleanup)
llvm::Instruction * CurrentFuncletPad
void Error(SourceLocation loc, StringRef error)
Emit a general error that something can&#39;t be done.
SourceLocation getExprLoc() const LLVM_READONLY
getExprLoc - Return the preferred location for the arrow when diagnosing a problem with a generic exp...
Definition: Expr.cpp:216
llvm::Value * EmitScalarExpr(const Expr *E, bool IgnoreResultAssign=false)
EmitScalarExpr - Emit the computation of the specified expression of LLVM scalar type, returning the result.
Dataflow Directional Tag Classes.
Stmt * getReturnStmtOnAllocFailure() const
Definition: StmtCXX.h:396
Expr * getAllocate() const
Definition: StmtCXX.h:385
static AggValueSlot ignored()
ignored - Returns an aggregate value slot indicating that the aggregate value is being ignored...
Definition: CGValue.h:499
Represents a &#39;co_yield&#39; expression.
Definition: ExprCXX.h:4423
Expr * getOperand() const
Retrieve the operand of the &#39;co_return&#39; statement.
Definition: StmtCXX.h:456
const Decl * getSingleDecl() const
Definition: Stmt.h:522
llvm::Function * getIntrinsic(unsigned IID, ArrayRef< llvm::Type *> Tys=None)
Stmt * getInitSuspendStmt() const
Definition: StmtCXX.h:371
llvm::StoreInst * CreateStore(llvm::Value *Val, Address Addr, bool IsVolatile=false)
Definition: CGBuilder.h:108
AwaitKind
Definition: CGCoroutine.cpp:27
bool isSingleDecl() const
isSingleDecl - This method returns true if this DeclStmt refers to a single Decl. ...
Definition: Stmt.h:518
void EmitCoreturnStmt(const CoreturnStmt &S)
static void emitBodyAndFallthrough(CodeGenFunction &CGF, const CoroutineBodyStmt &S, Stmt *Body)
llvm::DenseMap< const Decl *, Address > DeclMapTy
void EmitAutoVarCleanups(const AutoVarEmission &emission)
Definition: CGDecl.cpp:1600
static void createCoroData(CodeGenFunction &CGF, CodeGenFunction::CGCoroInfo &CurCoro, llvm::CallInst *CoroId, CallExpr const *CoroIdExpr=nullptr)
Definition: CGCoroutine.cpp:90
Represents the body of a coroutine.
Definition: StmtCXX.h:299
Represents a &#39;co_await&#39; expression.
Definition: ExprCXX.h:4340
void EmitBlock(llvm::BasicBlock *BB, bool IsFinished=false)
EmitBlock - Emit the given block.
Definition: CGStmt.cpp:445
void EnterCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock=false)
Represents an expression that might suspend coroutine execution; either a co_await or co_yield expres...
Definition: ExprCXX.h:4257
Expr * getResumeExpr() const
Definition: ExprCXX.h:4319
static OpaqueValueMappingData bind(CodeGenFunction &CGF, const OpaqueValueExpr *ov, const Expr *e)
Expr * getPromiseCall() const
Retrieve the promise call that results from this &#39;co_return&#39; statement.
Definition: StmtCXX.h:461
LValue EmitCoawaitLValue(const CoawaitExpr *E)
bool isVoidType() const
Definition: Type.h:6404
Stmt * getFallthroughHandler() const
Definition: StmtCXX.h:381
static CXXTryStmt * Create(const ASTContext &C, SourceLocation tryLoc, Stmt *tryBlock, ArrayRef< Stmt *> handlers)
Definition: StmtCXX.cpp:26
CXXCatchStmt - This represents a C++ catch block.
Definition: StmtCXX.h:29
LValue EmitLValue(const Expr *E)
EmitLValue - Emit code to compute a designator that specifies the location of the expression...
Definition: CGExpr.cpp:1232
CallExpr - Represents a function call (C99 6.5.2.2, C++ [expr.call]).
Definition: Expr.h:2285
Stmt * getBody() const
Retrieve the body of the coroutine as written.
Definition: StmtCXX.h:360
A reference to a declared variable, function, enum, etc.
Definition: Expr.h:971
static RValue get(llvm::Value *V)
Definition: CGValue.h:86
void ExitCXXTryStmt(const CXXTryStmt &S, bool IsFnTryBlock=false)
void EmitBranchThroughCleanup(JumpDest Dest)
EmitBranchThroughCleanup - Emit a branch from the current insert block through the normal cleanup han...
Definition: CGCleanup.cpp:1050
LValue - This represents an lvalue references.
Definition: CGValue.h:167
SourceLocation getBeginLoc() const LLVM_READONLY
Definition: Expr.cpp:1361
Information for lazily generating a cleanup.
Definition: EHScopeStack.h:147
Stmt * getFinalSuspendStmt() const
Definition: StmtCXX.h:374