clang  10.0.0svn
CGCoroutine.cpp
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1 //===----- CGCoroutine.cpp - Emit LLVM Code for C++ coroutines ------------===//
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 dealing with C++ code generation of coroutines.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "CGCleanup.h"
14 #include "CodeGenFunction.h"
15 #include "llvm/ADT/ScopeExit.h"
16 #include "clang/AST/StmtCXX.h"
17 #include "clang/AST/StmtVisitor.h"
18 
19 using namespace clang;
20 using namespace CodeGen;
21 
22 using llvm::Value;
23 using llvm::BasicBlock;
24 
25 namespace {
26 enum class AwaitKind { Init, Normal, Yield, Final };
27 static constexpr llvm::StringLiteral AwaitKindStr[] = {"init", "await", "yield",
28  "final"};
29 }
30 
32  // What is the current await expression kind and how many
33  // await/yield expressions were encountered so far.
34  // These are used to generate pretty labels for await expressions in LLVM IR.
35  AwaitKind CurrentAwaitKind = AwaitKind::Init;
36  unsigned AwaitNum = 0;
37  unsigned YieldNum = 0;
38 
39  // How many co_return statements are in the coroutine. Used to decide whether
40  // we need to add co_return; equivalent at the end of the user authored body.
41  unsigned CoreturnCount = 0;
42 
43  // A branch to this block is emitted when coroutine needs to suspend.
44  llvm::BasicBlock *SuspendBB = nullptr;
45 
46  // The promise type's 'unhandled_exception' handler, if it defines one.
47  Stmt *ExceptionHandler = nullptr;
48 
49  // A temporary i1 alloca that stores whether 'await_resume' threw an
50  // exception. If it did, 'true' is stored in this variable, and the coroutine
51  // body must be skipped. If the promise type does not define an exception
52  // handler, this is null.
53  llvm::Value *ResumeEHVar = nullptr;
54 
55  // Stores the jump destination just before the coroutine memory is freed.
56  // This is the destination that every suspend point jumps to for the cleanup
57  // branch.
59 
60  // Stores the jump destination just before the final suspend. The co_return
61  // statements jumps to this point after calling return_xxx promise member.
63 
64  // Stores the llvm.coro.id emitted in the function so that we can supply it
65  // as the first argument to coro.begin, coro.alloc and coro.free intrinsics.
66  // Note: llvm.coro.id returns a token that cannot be directly expressed in a
67  // builtin.
68  llvm::CallInst *CoroId = nullptr;
69 
70  // Stores the llvm.coro.begin emitted in the function so that we can replace
71  // all coro.frame intrinsics with direct SSA value of coro.begin that returns
72  // the address of the coroutine frame of the current coroutine.
73  llvm::CallInst *CoroBegin = nullptr;
74 
75  // Stores the last emitted coro.free for the deallocate expressions, we use it
76  // to wrap dealloc code with if(auto mem = coro.free) dealloc(mem).
77  llvm::CallInst *LastCoroFree = nullptr;
78 
79  // If coro.id came from the builtin, remember the expression to give better
80  // diagnostic. If CoroIdExpr is nullptr, the coro.id was created by
81  // EmitCoroutineBody.
82  CallExpr const *CoroIdExpr = nullptr;
83 };
84 
85 // Defining these here allows to keep CGCoroData private to this file.
88 
91  llvm::CallInst *CoroId,
92  CallExpr const *CoroIdExpr = nullptr) {
93  if (CurCoro.Data) {
94  if (CurCoro.Data->CoroIdExpr)
95  CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
96  "only one __builtin_coro_id can be used in a function");
97  else if (CoroIdExpr)
98  CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
99  "__builtin_coro_id shall not be used in a C++ coroutine");
100  else
101  llvm_unreachable("EmitCoroutineBodyStatement called twice?");
102 
103  return;
104  }
105 
106  CurCoro.Data = std::unique_ptr<CGCoroData>(new CGCoroData);
107  CurCoro.Data->CoroId = CoroId;
108  CurCoro.Data->CoroIdExpr = CoroIdExpr;
109 }
110 
111 // Synthesize a pretty name for a suspend point.
113  unsigned No = 0;
114  switch (Kind) {
115  case AwaitKind::Init:
116  case AwaitKind::Final:
117  break;
118  case AwaitKind::Normal:
119  No = ++Coro.AwaitNum;
120  break;
121  case AwaitKind::Yield:
122  No = ++Coro.YieldNum;
123  break;
124  }
125  SmallString<32> Prefix(AwaitKindStr[static_cast<unsigned>(Kind)]);
126  if (No > 1) {
127  Twine(No).toVector(Prefix);
128  }
129  return Prefix;
130 }
131 
132 static bool memberCallExpressionCanThrow(const Expr *E) {
133  if (const auto *CE = dyn_cast<CXXMemberCallExpr>(E))
134  if (const auto *Proto =
135  CE->getMethodDecl()->getType()->getAs<FunctionProtoType>())
136  if (isNoexceptExceptionSpec(Proto->getExceptionSpecType()) &&
137  Proto->canThrow() == CT_Cannot)
138  return false;
139  return true;
140 }
141 
142 // Emit suspend expression which roughly looks like:
143 //
144 // auto && x = CommonExpr();
145 // if (!x.await_ready()) {
146 // llvm_coro_save();
147 // x.await_suspend(...); (*)
148 // llvm_coro_suspend(); (**)
149 // }
150 // x.await_resume();
151 //
152 // where the result of the entire expression is the result of x.await_resume()
153 //
154 // (*) If x.await_suspend return type is bool, it allows to veto a suspend:
155 // if (x.await_suspend(...))
156 // llvm_coro_suspend();
157 //
158 // (**) llvm_coro_suspend() encodes three possible continuations as
159 // a switch instruction:
160 //
161 // %where-to = call i8 @llvm.coro.suspend(...)
162 // switch i8 %where-to, label %coro.ret [ ; jump to epilogue to suspend
163 // i8 0, label %yield.ready ; go here when resumed
164 // i8 1, label %yield.cleanup ; go here when destroyed
165 // ]
166 //
167 // See llvm's docs/Coroutines.rst for more details.
168 //
169 namespace {
170  struct LValueOrRValue {
171  LValue LV;
172  RValue RV;
173  };
174 }
175 static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Coro,
176  CoroutineSuspendExpr const &S,
177  AwaitKind Kind, AggValueSlot aggSlot,
178  bool ignoreResult, bool forLValue) {
179  auto *E = S.getCommonExpr();
180 
181  auto Binder =
183  auto UnbindOnExit = llvm::make_scope_exit([&] { Binder.unbind(CGF); });
184 
185  auto Prefix = buildSuspendPrefixStr(Coro, Kind);
186  BasicBlock *ReadyBlock = CGF.createBasicBlock(Prefix + Twine(".ready"));
187  BasicBlock *SuspendBlock = CGF.createBasicBlock(Prefix + Twine(".suspend"));
188  BasicBlock *CleanupBlock = CGF.createBasicBlock(Prefix + Twine(".cleanup"));
189 
190  // If expression is ready, no need to suspend.
191  CGF.EmitBranchOnBoolExpr(S.getReadyExpr(), ReadyBlock, SuspendBlock, 0);
192 
193  // Otherwise, emit suspend logic.
194  CGF.EmitBlock(SuspendBlock);
195 
196  auto &Builder = CGF.Builder;
197  llvm::Function *CoroSave = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_save);
198  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.CGM.Int8PtrTy);
199  auto *SaveCall = Builder.CreateCall(CoroSave, {NullPtr});
200 
201  auto *SuspendRet = CGF.EmitScalarExpr(S.getSuspendExpr());
202  if (SuspendRet != nullptr && SuspendRet->getType()->isIntegerTy(1)) {
203  // Veto suspension if requested by bool returning await_suspend.
204  BasicBlock *RealSuspendBlock =
205  CGF.createBasicBlock(Prefix + Twine(".suspend.bool"));
206  CGF.Builder.CreateCondBr(SuspendRet, RealSuspendBlock, ReadyBlock);
207  CGF.EmitBlock(RealSuspendBlock);
208  }
209 
210  // Emit the suspend point.
211  const bool IsFinalSuspend = (Kind == AwaitKind::Final);
212  llvm::Function *CoroSuspend =
213  CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_suspend);
214  auto *SuspendResult = Builder.CreateCall(
215  CoroSuspend, {SaveCall, Builder.getInt1(IsFinalSuspend)});
216 
217  // Create a switch capturing three possible continuations.
218  auto *Switch = Builder.CreateSwitch(SuspendResult, Coro.SuspendBB, 2);
219  Switch->addCase(Builder.getInt8(0), ReadyBlock);
220  Switch->addCase(Builder.getInt8(1), CleanupBlock);
221 
222  // Emit cleanup for this suspend point.
223  CGF.EmitBlock(CleanupBlock);
225 
226  // Emit await_resume expression.
227  CGF.EmitBlock(ReadyBlock);
228 
229  // Exception handling requires additional IR. If the 'await_resume' function
230  // is marked as 'noexcept', we avoid generating this additional IR.
231  CXXTryStmt *TryStmt = nullptr;
232  if (Coro.ExceptionHandler && Kind == AwaitKind::Init &&
234  Coro.ResumeEHVar =
235  CGF.CreateTempAlloca(Builder.getInt1Ty(), Prefix + Twine("resume.eh"));
236  Builder.CreateFlagStore(true, Coro.ResumeEHVar);
237 
238  auto Loc = S.getResumeExpr()->getExprLoc();
239  auto *Catch = new (CGF.getContext())
240  CXXCatchStmt(Loc, /*exDecl=*/nullptr, Coro.ExceptionHandler);
241  auto *TryBody =
242  CompoundStmt::Create(CGF.getContext(), S.getResumeExpr(), Loc, Loc);
243  TryStmt = CXXTryStmt::Create(CGF.getContext(), Loc, TryBody, Catch);
244  CGF.EnterCXXTryStmt(*TryStmt);
245  }
246 
247  LValueOrRValue Res;
248  if (forLValue)
249  Res.LV = CGF.EmitLValue(S.getResumeExpr());
250  else
251  Res.RV = CGF.EmitAnyExpr(S.getResumeExpr(), aggSlot, ignoreResult);
252 
253  if (TryStmt) {
254  Builder.CreateFlagStore(false, Coro.ResumeEHVar);
255  CGF.ExitCXXTryStmt(*TryStmt);
256  }
257 
258  return Res;
259 }
260 
262  AggValueSlot aggSlot,
263  bool ignoreResult) {
264  return emitSuspendExpression(*this, *CurCoro.Data, E,
265  CurCoro.Data->CurrentAwaitKind, aggSlot,
266  ignoreResult, /*forLValue*/false).RV;
267 }
269  AggValueSlot aggSlot,
270  bool ignoreResult) {
271  return emitSuspendExpression(*this, *CurCoro.Data, E, AwaitKind::Yield,
272  aggSlot, ignoreResult, /*forLValue*/false).RV;
273 }
274 
276  ++CurCoro.Data->CoreturnCount;
277  const Expr *RV = S.getOperand();
278  if (RV && RV->getType()->isVoidType()) {
279  // Make sure to evaluate the expression of a co_return with a void
280  // expression for side effects.
281  RunCleanupsScope cleanupScope(*this);
282  EmitIgnoredExpr(RV);
283  }
284  EmitStmt(S.getPromiseCall());
285  EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
286 }
287 
288 
289 #ifndef NDEBUG
291  const CoroutineSuspendExpr *E) {
292  const auto *RE = E->getResumeExpr();
293  // Is it possible for RE to be a CXXBindTemporaryExpr wrapping
294  // a MemberCallExpr?
295  assert(isa<CallExpr>(RE) && "unexpected suspend expression type");
296  return cast<CallExpr>(RE)->getCallReturnType(Ctx);
297 }
298 #endif
299 
300 LValue
302  assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
303  "Can't have a scalar return unless the return type is a "
304  "reference type!");
305  return emitSuspendExpression(*this, *CurCoro.Data, *E,
306  CurCoro.Data->CurrentAwaitKind, AggValueSlot::ignored(),
307  /*ignoreResult*/false, /*forLValue*/true).LV;
308 }
309 
310 LValue
312  assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
313  "Can't have a scalar return unless the return type is a "
314  "reference type!");
315  return emitSuspendExpression(*this, *CurCoro.Data, *E,
316  AwaitKind::Yield, AggValueSlot::ignored(),
317  /*ignoreResult*/false, /*forLValue*/true).LV;
318 }
319 
320 // Hunts for the parameter reference in the parameter copy/move declaration.
321 namespace {
322 struct GetParamRef : public StmtVisitor<GetParamRef> {
323 public:
324  DeclRefExpr *Expr = nullptr;
325  GetParamRef() {}
326  void VisitDeclRefExpr(DeclRefExpr *E) {
327  assert(Expr == nullptr && "multilple declref in param move");
328  Expr = E;
329  }
330  void VisitStmt(Stmt *S) {
331  for (auto *C : S->children()) {
332  if (C)
333  Visit(C);
334  }
335  }
336 };
337 }
338 
339 // This class replaces references to parameters to their copies by changing
340 // the addresses in CGF.LocalDeclMap and restoring back the original values in
341 // its destructor.
342 
343 namespace {
344  struct ParamReferenceReplacerRAII {
345  CodeGenFunction::DeclMapTy SavedLocals;
346  CodeGenFunction::DeclMapTy& LocalDeclMap;
347 
348  ParamReferenceReplacerRAII(CodeGenFunction::DeclMapTy &LocalDeclMap)
349  : LocalDeclMap(LocalDeclMap) {}
350 
351  void addCopy(DeclStmt const *PM) {
352  // Figure out what param it refers to.
353 
354  assert(PM->isSingleDecl());
355  VarDecl const*VD = static_cast<VarDecl const*>(PM->getSingleDecl());
356  Expr const *InitExpr = VD->getInit();
357  GetParamRef Visitor;
358  Visitor.Visit(const_cast<Expr*>(InitExpr));
359  assert(Visitor.Expr);
360  DeclRefExpr *DREOrig = Visitor.Expr;
361  auto *PD = DREOrig->getDecl();
362 
363  auto it = LocalDeclMap.find(PD);
364  assert(it != LocalDeclMap.end() && "parameter is not found");
365  SavedLocals.insert({ PD, it->second });
366 
367  auto copyIt = LocalDeclMap.find(VD);
368  assert(copyIt != LocalDeclMap.end() && "parameter copy is not found");
369  it->second = copyIt->getSecond();
370  }
371 
372  ~ParamReferenceReplacerRAII() {
373  for (auto&& SavedLocal : SavedLocals) {
374  LocalDeclMap.insert({SavedLocal.first, SavedLocal.second});
375  }
376  }
377  };
378 }
379 
380 // For WinEH exception representation backend needs to know what funclet coro.end
381 // belongs to. That information is passed in a funclet bundle.
385 
386  if (llvm::Instruction *EHPad = CGF.CurrentFuncletPad)
387  BundleList.emplace_back("funclet", EHPad);
388 
389  return BundleList;
390 }
391 
392 namespace {
393 // We will insert coro.end to cut any of the destructors for objects that
394 // do not need to be destroyed once the coroutine is resumed.
395 // See llvm/docs/Coroutines.rst for more details about coro.end.
396 struct CallCoroEnd final : public EHScopeStack::Cleanup {
397  void Emit(CodeGenFunction &CGF, Flags flags) override {
398  auto &CGM = CGF.CGM;
399  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
400  llvm::Function *CoroEndFn = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
401  // See if we have a funclet bundle to associate coro.end with. (WinEH)
402  auto Bundles = getBundlesForCoroEnd(CGF);
403  auto *CoroEnd = CGF.Builder.CreateCall(
404  CoroEndFn, {NullPtr, CGF.Builder.getTrue()}, Bundles);
405  if (Bundles.empty()) {
406  // Otherwise, (landingpad model), create a conditional branch that leads
407  // either to a cleanup block or a block with EH resume instruction.
408  auto *ResumeBB = CGF.getEHResumeBlock(/*isCleanup=*/true);
409  auto *CleanupContBB = CGF.createBasicBlock("cleanup.cont");
410  CGF.Builder.CreateCondBr(CoroEnd, ResumeBB, CleanupContBB);
411  CGF.EmitBlock(CleanupContBB);
412  }
413  }
414 };
415 }
416 
417 namespace {
418 // Make sure to call coro.delete on scope exit.
419 struct CallCoroDelete final : public EHScopeStack::Cleanup {
420  Stmt *Deallocate;
421 
422  // Emit "if (coro.free(CoroId, CoroBegin)) Deallocate;"
423 
424  // Note: That deallocation will be emitted twice: once for a normal exit and
425  // once for exceptional exit. This usage is safe because Deallocate does not
426  // contain any declarations. The SubStmtBuilder::makeNewAndDeleteExpr()
427  // builds a single call to a deallocation function which is safe to emit
428  // multiple times.
429  void Emit(CodeGenFunction &CGF, Flags) override {
430  // Remember the current point, as we are going to emit deallocation code
431  // first to get to coro.free instruction that is an argument to a delete
432  // call.
433  BasicBlock *SaveInsertBlock = CGF.Builder.GetInsertBlock();
434 
435  auto *FreeBB = CGF.createBasicBlock("coro.free");
436  CGF.EmitBlock(FreeBB);
437  CGF.EmitStmt(Deallocate);
438 
439  auto *AfterFreeBB = CGF.createBasicBlock("after.coro.free");
440  CGF.EmitBlock(AfterFreeBB);
441 
442  // We should have captured coro.free from the emission of deallocate.
443  auto *CoroFree = CGF.CurCoro.Data->LastCoroFree;
444  if (!CoroFree) {
445  CGF.CGM.Error(Deallocate->getBeginLoc(),
446  "Deallocation expressoin does not refer to coro.free");
447  return;
448  }
449 
450  // Get back to the block we were originally and move coro.free there.
451  auto *InsertPt = SaveInsertBlock->getTerminator();
452  CoroFree->moveBefore(InsertPt);
453  CGF.Builder.SetInsertPoint(InsertPt);
454 
455  // Add if (auto *mem = coro.free) Deallocate;
456  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
457  auto *Cond = CGF.Builder.CreateICmpNE(CoroFree, NullPtr);
458  CGF.Builder.CreateCondBr(Cond, FreeBB, AfterFreeBB);
459 
460  // No longer need old terminator.
461  InsertPt->eraseFromParent();
462  CGF.Builder.SetInsertPoint(AfterFreeBB);
463  }
464  explicit CallCoroDelete(Stmt *DeallocStmt) : Deallocate(DeallocStmt) {}
465 };
466 }
467 
468 namespace {
469 struct GetReturnObjectManager {
470  CodeGenFunction &CGF;
471  CGBuilderTy &Builder;
472  const CoroutineBodyStmt &S;
473 
474  Address GroActiveFlag;
476 
477  GetReturnObjectManager(CodeGenFunction &CGF, const CoroutineBodyStmt &S)
478  : CGF(CGF), Builder(CGF.Builder), S(S), GroActiveFlag(Address::invalid()),
480 
481  // The gro variable has to outlive coroutine frame and coroutine promise, but,
482  // it can only be initialized after coroutine promise was created, thus, we
483  // split its emission in two parts. EmitGroAlloca emits an alloca and sets up
484  // cleanups. Later when coroutine promise is available we initialize the gro
485  // and sets the flag that the cleanup is now active.
486 
487  void EmitGroAlloca() {
488  auto *GroDeclStmt = dyn_cast<DeclStmt>(S.getResultDecl());
489  if (!GroDeclStmt) {
490  // If get_return_object returns void, no need to do an alloca.
491  return;
492  }
493 
494  auto *GroVarDecl = cast<VarDecl>(GroDeclStmt->getSingleDecl());
495 
496  // Set GRO flag that it is not initialized yet
497  GroActiveFlag =
498  CGF.CreateTempAlloca(Builder.getInt1Ty(), CharUnits::One(), "gro.active");
499  Builder.CreateStore(Builder.getFalse(), GroActiveFlag);
500 
501  GroEmission = CGF.EmitAutoVarAlloca(*GroVarDecl);
502 
503  // Remember the top of EHStack before emitting the cleanup.
504  auto old_top = CGF.EHStack.stable_begin();
505  CGF.EmitAutoVarCleanups(GroEmission);
506  auto top = CGF.EHStack.stable_begin();
507 
508  // Make the cleanup conditional on gro.active
509  for (auto b = CGF.EHStack.find(top), e = CGF.EHStack.find(old_top);
510  b != e; b++) {
511  if (auto *Cleanup = dyn_cast<EHCleanupScope>(&*b)) {
512  assert(!Cleanup->hasActiveFlag() && "cleanup already has active flag?");
513  Cleanup->setActiveFlag(GroActiveFlag);
514  Cleanup->setTestFlagInEHCleanup();
515  Cleanup->setTestFlagInNormalCleanup();
516  }
517  }
518  }
519 
520  void EmitGroInit() {
521  if (!GroActiveFlag.isValid()) {
522  // No Gro variable was allocated. Simply emit the call to
523  // get_return_object.
524  CGF.EmitStmt(S.getResultDecl());
525  return;
526  }
527 
528  CGF.EmitAutoVarInit(GroEmission);
529  Builder.CreateStore(Builder.getTrue(), GroActiveFlag);
530  }
531 };
532 }
533 
535  const CoroutineBodyStmt &S, Stmt *Body) {
536  CGF.EmitStmt(Body);
537  const bool CanFallthrough = CGF.Builder.GetInsertBlock();
538  if (CanFallthrough)
539  if (Stmt *OnFallthrough = S.getFallthroughHandler())
540  CGF.EmitStmt(OnFallthrough);
541 }
542 
544  auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
545  auto &TI = CGM.getContext().getTargetInfo();
546  unsigned NewAlign = TI.getNewAlign() / TI.getCharWidth();
547 
548  auto *EntryBB = Builder.GetInsertBlock();
549  auto *AllocBB = createBasicBlock("coro.alloc");
550  auto *InitBB = createBasicBlock("coro.init");
551  auto *FinalBB = createBasicBlock("coro.final");
552  auto *RetBB = createBasicBlock("coro.ret");
553 
554  auto *CoroId = Builder.CreateCall(
555  CGM.getIntrinsic(llvm::Intrinsic::coro_id),
556  {Builder.getInt32(NewAlign), NullPtr, NullPtr, NullPtr});
557  createCoroData(*this, CurCoro, CoroId);
558  CurCoro.Data->SuspendBB = RetBB;
559 
560  // Backend is allowed to elide memory allocations, to help it, emit
561  // auto mem = coro.alloc() ? 0 : ... allocation code ...;
562  auto *CoroAlloc = Builder.CreateCall(
563  CGM.getIntrinsic(llvm::Intrinsic::coro_alloc), {CoroId});
564 
565  Builder.CreateCondBr(CoroAlloc, AllocBB, InitBB);
566 
567  EmitBlock(AllocBB);
568  auto *AllocateCall = EmitScalarExpr(S.getAllocate());
569  auto *AllocOrInvokeContBB = Builder.GetInsertBlock();
570 
571  // Handle allocation failure if 'ReturnStmtOnAllocFailure' was provided.
572  if (auto *RetOnAllocFailure = S.getReturnStmtOnAllocFailure()) {
573  auto *RetOnFailureBB = createBasicBlock("coro.ret.on.failure");
574 
575  // See if allocation was successful.
576  auto *NullPtr = llvm::ConstantPointerNull::get(Int8PtrTy);
577  auto *Cond = Builder.CreateICmpNE(AllocateCall, NullPtr);
578  Builder.CreateCondBr(Cond, InitBB, RetOnFailureBB);
579 
580  // If not, return OnAllocFailure object.
581  EmitBlock(RetOnFailureBB);
582  EmitStmt(RetOnAllocFailure);
583  }
584  else {
585  Builder.CreateBr(InitBB);
586  }
587 
588  EmitBlock(InitBB);
589 
590  // Pass the result of the allocation to coro.begin.
591  auto *Phi = Builder.CreatePHI(VoidPtrTy, 2);
592  Phi->addIncoming(NullPtr, EntryBB);
593  Phi->addIncoming(AllocateCall, AllocOrInvokeContBB);
594  auto *CoroBegin = Builder.CreateCall(
595  CGM.getIntrinsic(llvm::Intrinsic::coro_begin), {CoroId, Phi});
596  CurCoro.Data->CoroBegin = CoroBegin;
597 
598  GetReturnObjectManager GroManager(*this, S);
599  GroManager.EmitGroAlloca();
600 
601  CurCoro.Data->CleanupJD = getJumpDestInCurrentScope(RetBB);
602  {
603  ParamReferenceReplacerRAII ParamReplacer(LocalDeclMap);
604  CodeGenFunction::RunCleanupsScope ResumeScope(*this);
605  EHStack.pushCleanup<CallCoroDelete>(NormalAndEHCleanup, S.getDeallocate());
606 
607  // Create parameter copies. We do it before creating a promise, since an
608  // evolution of coroutine TS may allow promise constructor to observe
609  // parameter copies.
610  for (auto *PM : S.getParamMoves()) {
611  EmitStmt(PM);
612  ParamReplacer.addCopy(cast<DeclStmt>(PM));
613  // TODO: if(CoroParam(...)) need to surround ctor and dtor
614  // for the copy, so that llvm can elide it if the copy is
615  // not needed.
616  }
617 
618  EmitStmt(S.getPromiseDeclStmt());
619 
620  Address PromiseAddr = GetAddrOfLocalVar(S.getPromiseDecl());
621  auto *PromiseAddrVoidPtr =
622  new llvm::BitCastInst(PromiseAddr.getPointer(), VoidPtrTy, "", CoroId);
623  // Update CoroId to refer to the promise. We could not do it earlier because
624  // promise local variable was not emitted yet.
625  CoroId->setArgOperand(1, PromiseAddrVoidPtr);
626 
627  // Now we have the promise, initialize the GRO
628  GroManager.EmitGroInit();
629 
630  EHStack.pushCleanup<CallCoroEnd>(EHCleanup);
631 
632  CurCoro.Data->CurrentAwaitKind = AwaitKind::Init;
633  CurCoro.Data->ExceptionHandler = S.getExceptionHandler();
634  EmitStmt(S.getInitSuspendStmt());
635  CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
636 
637  CurCoro.Data->CurrentAwaitKind = AwaitKind::Normal;
638 
639  if (CurCoro.Data->ExceptionHandler) {
640  // If we generated IR to record whether an exception was thrown from
641  // 'await_resume', then use that IR to determine whether the coroutine
642  // body should be skipped.
643  // If we didn't generate the IR (perhaps because 'await_resume' was marked
644  // as 'noexcept'), then we skip this check.
645  BasicBlock *ContBB = nullptr;
646  if (CurCoro.Data->ResumeEHVar) {
647  BasicBlock *BodyBB = createBasicBlock("coro.resumed.body");
648  ContBB = createBasicBlock("coro.resumed.cont");
649  Value *SkipBody = Builder.CreateFlagLoad(CurCoro.Data->ResumeEHVar,
650  "coro.resumed.eh");
651  Builder.CreateCondBr(SkipBody, ContBB, BodyBB);
652  EmitBlock(BodyBB);
653  }
654 
655  auto Loc = S.getBeginLoc();
656  CXXCatchStmt Catch(Loc, /*exDecl=*/nullptr,
657  CurCoro.Data->ExceptionHandler);
658  auto *TryStmt =
659  CXXTryStmt::Create(getContext(), Loc, S.getBody(), &Catch);
660 
661  EnterCXXTryStmt(*TryStmt);
662  emitBodyAndFallthrough(*this, S, TryStmt->getTryBlock());
663  ExitCXXTryStmt(*TryStmt);
664 
665  if (ContBB)
666  EmitBlock(ContBB);
667  }
668  else {
669  emitBodyAndFallthrough(*this, S, S.getBody());
670  }
671 
672  // See if we need to generate final suspend.
673  const bool CanFallthrough = Builder.GetInsertBlock();
674  const bool HasCoreturns = CurCoro.Data->CoreturnCount > 0;
675  if (CanFallthrough || HasCoreturns) {
676  EmitBlock(FinalBB);
677  CurCoro.Data->CurrentAwaitKind = AwaitKind::Final;
678  EmitStmt(S.getFinalSuspendStmt());
679  } else {
680  // We don't need FinalBB. Emit it to make sure the block is deleted.
681  EmitBlock(FinalBB, /*IsFinished=*/true);
682  }
683  }
684 
685  EmitBlock(RetBB);
686  // Emit coro.end before getReturnStmt (and parameter destructors), since
687  // resume and destroy parts of the coroutine should not include them.
688  llvm::Function *CoroEnd = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
689  Builder.CreateCall(CoroEnd, {NullPtr, Builder.getFalse()});
690 
691  if (Stmt *Ret = S.getReturnStmt())
692  EmitStmt(Ret);
693 }
694 
695 // Emit coroutine intrinsic and patch up arguments of the token type.
697  unsigned int IID) {
699  switch (IID) {
700  default:
701  break;
702  // The coro.frame builtin is replaced with an SSA value of the coro.begin
703  // intrinsic.
704  case llvm::Intrinsic::coro_frame: {
705  if (CurCoro.Data && CurCoro.Data->CoroBegin) {
706  return RValue::get(CurCoro.Data->CoroBegin);
707  }
708  CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_begin "
709  "has been used earlier in this function");
710  auto NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
711  return RValue::get(NullPtr);
712  }
713  // The following three intrinsics take a token parameter referring to a token
714  // returned by earlier call to @llvm.coro.id. Since we cannot represent it in
715  // builtins, we patch it up here.
716  case llvm::Intrinsic::coro_alloc:
717  case llvm::Intrinsic::coro_begin:
718  case llvm::Intrinsic::coro_free: {
719  if (CurCoro.Data && CurCoro.Data->CoroId) {
720  Args.push_back(CurCoro.Data->CoroId);
721  break;
722  }
723  CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_id has"
724  " been used earlier in this function");
725  // Fallthrough to the next case to add TokenNone as the first argument.
726  LLVM_FALLTHROUGH;
727  }
728  // @llvm.coro.suspend takes a token parameter. Add token 'none' as the first
729  // argument.
730  case llvm::Intrinsic::coro_suspend:
731  Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
732  break;
733  }
734  for (const Expr *Arg : E->arguments())
735  Args.push_back(EmitScalarExpr(Arg));
736 
737  llvm::Function *F = CGM.getIntrinsic(IID);
738  llvm::CallInst *Call = Builder.CreateCall(F, Args);
739 
740  // Note: The following code is to enable to emit coro.id and coro.begin by
741  // hand to experiment with coroutines in C.
742  // If we see @llvm.coro.id remember it in the CoroData. We will update
743  // coro.alloc, coro.begin and coro.free intrinsics to refer to it.
744  if (IID == llvm::Intrinsic::coro_id) {
745  createCoroData(*this, CurCoro, Call, E);
746  }
747  else if (IID == llvm::Intrinsic::coro_begin) {
748  if (CurCoro.Data)
749  CurCoro.Data->CoroBegin = Call;
750  }
751  else if (IID == llvm::Intrinsic::coro_free) {
752  // Remember the last coro_free as we need it to build the conditional
753  // deletion of the coroutine frame.
754  if (CurCoro.Data)
755  CurCoro.Data->LastCoroFree = Call;
756  }
757  return RValue::get(Call);
758 }
Expr * getReadyExpr() const
Definition: ExprCXX.h:4582
void EmitCoroutineBody(const CoroutineBodyStmt &S)
A (possibly-)qualified type.
Definition: Type.h:643
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:456
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:382
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:590
stable_iterator stable_begin() const
Create a stable reference to the top of the EH stack.
Definition: EHScopeStack.h:378
Stmt * getExceptionHandler() const
Definition: StmtCXX.h:396
Expr * getDeallocate() const
Definition: StmtCXX.h:406
Represents a variable declaration or definition.
Definition: Decl.h:827
Stmt * getResultDecl() const
Definition: StmtCXX.h:412
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:160
VarDecl * getPromiseDecl() const
Definition: StmtCXX.h:385
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:80
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:417
child_range children()
Definition: Stmt.cpp:223
static CompoundStmt * Create(const ASTContext &C, ArrayRef< Stmt *> Stmts, SourceLocation LB, SourceLocation RB)
Definition: Stmt.cpp:318
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:4580
Expr * getCommonExpr() const
Definition: ExprCXX.h:4575
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:413
static QualType getCoroutineSuspendExprReturnType(const ASTContext &Ctx, const CoroutineSuspendExpr *E)
bool isValid() const
Definition: Address.h:35
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:1375
Represents a prototype with parameter type info, e.g.
Definition: Type.h:3725
RValue - This trivial value class is used to represent the result of an expression that is evaluated...
Definition: CGValue.h:38
static SmallVector< llvm::OperandBundleDef, 1 > getBundlesForCoroEnd(CodeGenFunction &CGF)
static SmallString< 32 > buildSuspendPrefixStr(CGCoroData &Coro, AwaitKind Kind)
This represents one expression.
Definition: Expr.h:108
void EmitAutoVarInit(const AutoVarEmission &emission)
Definition: CGDecl.cpp:1742
static Address invalid()
Definition: Address.h:34
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:68
QualType getType() const
Definition: Expr.h:137
ValueDecl * getDecl()
Definition: Expr.h:1222
CodeGenFunction::JumpDest FinalJD
Definition: CGCoroutine.cpp:62
Kind
static bool Ret(InterpState &S, CodePtr &PC, APValue &Result)
Definition: Interp.cpp:34
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:1203
An aggregate value slot.
Definition: CGValue.h:436
SourceLocation getBeginLoc() const LLVM_READONLY
Definition: StmtCXX.h:421
CodeGenFunction::JumpDest CleanupJD
Definition: CGCoroutine.cpp:58
void EmitStmt(const Stmt *S, ArrayRef< const Attr *> Attrs=None)
EmitStmt - Emit the code for the statement.
Definition: CGStmt.cpp:44
StmtVisitor - This class implements a simple visitor for Stmt subclasses.
Definition: StmtVisitor.h:182
Expr * getSuspendExpr() const
Definition: ExprCXX.h:4586
arg_range arguments()
Definition: Expr.h:2714
An aligned address.
Definition: Address.h:24
llvm::BasicBlock * SuspendBB
Definition: CGCoroutine.cpp:44
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:221
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:414
Expr * getAllocate() const
Definition: StmtCXX.h:403
static AggValueSlot ignored()
ignored - Returns an aggregate value slot indicating that the aggregate value is being ignored...
Definition: CGValue.h:498
Represents a &#39;co_yield&#39; expression.
Definition: ExprCXX.h:4702
Expr * getOperand() const
Retrieve the operand of the &#39;co_return&#39; statement.
Definition: StmtCXX.h:480
const Decl * getSingleDecl() const
Definition: Stmt.h:1218
llvm::Function * getIntrinsic(unsigned IID, ArrayRef< llvm::Type *> Tys=None)
Stmt * getInitSuspendStmt() const
Definition: StmtCXX.h:389
llvm::StoreInst * CreateStore(llvm::Value *Val, Address Addr, bool IsVolatile=false)
Definition: CGBuilder.h:107
AwaitKind
Definition: CGCoroutine.cpp:26
bool isSingleDecl() const
isSingleDecl - This method returns true if this DeclStmt refers to a single Decl. ...
Definition: Stmt.h:1216
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:1978
static void createCoroData(CodeGenFunction &CGF, CodeGenFunction::CGCoroInfo &CurCoro, llvm::CallInst *CoroId, CallExpr const *CoroIdExpr=nullptr)
Definition: CGCoroutine.cpp:89
Represents the body of a coroutine.
Definition: StmtCXX.h:317
Represents a &#39;co_await&#39; expression.
Definition: ExprCXX.h:4615
void EmitBlock(llvm::BasicBlock *BB, bool IsFinished=false)
EmitBlock - Emit the given block.
Definition: CGStmt.cpp:461
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:4528
Expr * getResumeExpr() const
Definition: ExprCXX.h:4590
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:485
LValue EmitCoawaitLValue(const CoawaitExpr *E)
bool isVoidType() const
Definition: Type.h:6650
Stmt * getFallthroughHandler() const
Definition: StmtCXX.h:399
static CXXTryStmt * Create(const ASTContext &C, SourceLocation tryLoc, Stmt *tryBlock, ArrayRef< Stmt *> handlers)
Definition: StmtCXX.cpp:25
CXXCatchStmt - This represents a C++ catch block.
Definition: StmtCXX.h:28
LValue EmitLValue(const Expr *E)
EmitLValue - Emit code to compute a designator that specifies the location of the expression...
Definition: CGExpr.cpp:1243
CallExpr - Represents a function call (C99 6.5.2.2, C++ [expr.call]).
Definition: Expr.h:2521
Stmt * getBody() const
Retrieve the body of the coroutine as written.
Definition: StmtCXX.h:378
A reference to a declared variable, function, enum, etc.
Definition: Expr.h:1146
static RValue get(llvm::Value *V)
Definition: CGValue.h:85
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:1044
LValue - This represents an lvalue references.
Definition: CGValue.h:166
SourceLocation getBeginLoc() const LLVM_READONLY
Definition: Expr.cpp:1528
Information for lazily generating a cleanup.
Definition: EHScopeStack.h:146
Stmt * getFinalSuspendStmt() const
Definition: StmtCXX.h:392