clang  9.0.0svn
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.
112 static SmallString<32> buildSuspendPrefixStr(CGCoroData &Coro, AwaitKind Kind) {
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  SuspendBlock = RealSuspendBlock;
208  CGF.EmitBlock(RealSuspendBlock);
209  }
210 
211  // Emit the suspend point.
212  const bool IsFinalSuspend = (Kind == AwaitKind::Final);
213  llvm::Function *CoroSuspend =
214  CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_suspend);
215  auto *SuspendResult = Builder.CreateCall(
216  CoroSuspend, {SaveCall, Builder.getInt1(IsFinalSuspend)});
217 
218  // Create a switch capturing three possible continuations.
219  auto *Switch = Builder.CreateSwitch(SuspendResult, Coro.SuspendBB, 2);
220  Switch->addCase(Builder.getInt8(0), ReadyBlock);
221  Switch->addCase(Builder.getInt8(1), CleanupBlock);
222 
223  // Emit cleanup for this suspend point.
224  CGF.EmitBlock(CleanupBlock);
226 
227  // Emit await_resume expression.
228  CGF.EmitBlock(ReadyBlock);
229 
230  // Exception handling requires additional IR. If the 'await_resume' function
231  // is marked as 'noexcept', we avoid generating this additional IR.
232  CXXTryStmt *TryStmt = nullptr;
233  if (Coro.ExceptionHandler && Kind == AwaitKind::Init &&
235  Coro.ResumeEHVar =
236  CGF.CreateTempAlloca(Builder.getInt1Ty(), Prefix + Twine("resume.eh"));
237  Builder.CreateFlagStore(true, Coro.ResumeEHVar);
238 
239  auto Loc = S.getResumeExpr()->getExprLoc();
240  auto *Catch = new (CGF.getContext())
241  CXXCatchStmt(Loc, /*exDecl=*/nullptr, Coro.ExceptionHandler);
242  auto *TryBody =
243  CompoundStmt::Create(CGF.getContext(), S.getResumeExpr(), Loc, Loc);
244  TryStmt = CXXTryStmt::Create(CGF.getContext(), Loc, TryBody, Catch);
245  CGF.EnterCXXTryStmt(*TryStmt);
246  }
247 
248  LValueOrRValue Res;
249  if (forLValue)
250  Res.LV = CGF.EmitLValue(S.getResumeExpr());
251  else
252  Res.RV = CGF.EmitAnyExpr(S.getResumeExpr(), aggSlot, ignoreResult);
253 
254  if (TryStmt) {
255  Builder.CreateFlagStore(false, Coro.ResumeEHVar);
256  CGF.ExitCXXTryStmt(*TryStmt);
257  }
258 
259  return Res;
260 }
261 
263  AggValueSlot aggSlot,
264  bool ignoreResult) {
265  return emitSuspendExpression(*this, *CurCoro.Data, E,
266  CurCoro.Data->CurrentAwaitKind, aggSlot,
267  ignoreResult, /*forLValue*/false).RV;
268 }
270  AggValueSlot aggSlot,
271  bool ignoreResult) {
272  return emitSuspendExpression(*this, *CurCoro.Data, E, AwaitKind::Yield,
273  aggSlot, ignoreResult, /*forLValue*/false).RV;
274 }
275 
277  ++CurCoro.Data->CoreturnCount;
278  const Expr *RV = S.getOperand();
279  if (RV && RV->getType()->isVoidType()) {
280  // Make sure to evaluate the expression of a co_return with a void
281  // expression for side effects.
282  RunCleanupsScope cleanupScope(*this);
283  EmitIgnoredExpr(RV);
284  }
285  EmitStmt(S.getPromiseCall());
286  EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
287 }
288 
289 
290 #ifndef NDEBUG
292  const CoroutineSuspendExpr *E) {
293  const auto *RE = E->getResumeExpr();
294  // Is it possible for RE to be a CXXBindTemporaryExpr wrapping
295  // a MemberCallExpr?
296  assert(isa<CallExpr>(RE) && "unexpected suspend expression type");
297  return cast<CallExpr>(RE)->getCallReturnType(Ctx);
298 }
299 #endif
300 
301 LValue
303  assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
304  "Can't have a scalar return unless the return type is a "
305  "reference type!");
306  return emitSuspendExpression(*this, *CurCoro.Data, *E,
307  CurCoro.Data->CurrentAwaitKind, AggValueSlot::ignored(),
308  /*ignoreResult*/false, /*forLValue*/true).LV;
309 }
310 
311 LValue
313  assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
314  "Can't have a scalar return unless the return type is a "
315  "reference type!");
316  return emitSuspendExpression(*this, *CurCoro.Data, *E,
317  AwaitKind::Yield, AggValueSlot::ignored(),
318  /*ignoreResult*/false, /*forLValue*/true).LV;
319 }
320 
321 // Hunts for the parameter reference in the parameter copy/move declaration.
322 namespace {
323 struct GetParamRef : public StmtVisitor<GetParamRef> {
324 public:
325  DeclRefExpr *Expr = nullptr;
326  GetParamRef() {}
327  void VisitDeclRefExpr(DeclRefExpr *E) {
328  assert(Expr == nullptr && "multilple declref in param move");
329  Expr = E;
330  }
331  void VisitStmt(Stmt *S) {
332  for (auto *C : S->children()) {
333  if (C)
334  Visit(C);
335  }
336  }
337 };
338 }
339 
340 // This class replaces references to parameters to their copies by changing
341 // the addresses in CGF.LocalDeclMap and restoring back the original values in
342 // its destructor.
343 
344 namespace {
345  struct ParamReferenceReplacerRAII {
346  CodeGenFunction::DeclMapTy SavedLocals;
347  CodeGenFunction::DeclMapTy& LocalDeclMap;
348 
349  ParamReferenceReplacerRAII(CodeGenFunction::DeclMapTy &LocalDeclMap)
350  : LocalDeclMap(LocalDeclMap) {}
351 
352  void addCopy(DeclStmt const *PM) {
353  // Figure out what param it refers to.
354 
355  assert(PM->isSingleDecl());
356  VarDecl const*VD = static_cast<VarDecl const*>(PM->getSingleDecl());
357  Expr const *InitExpr = VD->getInit();
358  GetParamRef Visitor;
359  Visitor.Visit(const_cast<Expr*>(InitExpr));
360  assert(Visitor.Expr);
361  DeclRefExpr *DREOrig = Visitor.Expr;
362  auto *PD = DREOrig->getDecl();
363 
364  auto it = LocalDeclMap.find(PD);
365  assert(it != LocalDeclMap.end() && "parameter is not found");
366  SavedLocals.insert({ PD, it->second });
367 
368  auto copyIt = LocalDeclMap.find(VD);
369  assert(copyIt != LocalDeclMap.end() && "parameter copy is not found");
370  it->second = copyIt->getSecond();
371  }
372 
373  ~ParamReferenceReplacerRAII() {
374  for (auto&& SavedLocal : SavedLocals) {
375  LocalDeclMap.insert({SavedLocal.first, SavedLocal.second});
376  }
377  }
378  };
379 }
380 
381 // For WinEH exception representation backend needs to know what funclet coro.end
382 // belongs to. That information is passed in a funclet bundle.
386 
387  if (llvm::Instruction *EHPad = CGF.CurrentFuncletPad)
388  BundleList.emplace_back("funclet", EHPad);
389 
390  return BundleList;
391 }
392 
393 namespace {
394 // We will insert coro.end to cut any of the destructors for objects that
395 // do not need to be destroyed once the coroutine is resumed.
396 // See llvm/docs/Coroutines.rst for more details about coro.end.
397 struct CallCoroEnd final : public EHScopeStack::Cleanup {
398  void Emit(CodeGenFunction &CGF, Flags flags) override {
399  auto &CGM = CGF.CGM;
400  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
401  llvm::Function *CoroEndFn = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
402  // See if we have a funclet bundle to associate coro.end with. (WinEH)
403  auto Bundles = getBundlesForCoroEnd(CGF);
404  auto *CoroEnd = CGF.Builder.CreateCall(
405  CoroEndFn, {NullPtr, CGF.Builder.getTrue()}, Bundles);
406  if (Bundles.empty()) {
407  // Otherwise, (landingpad model), create a conditional branch that leads
408  // either to a cleanup block or a block with EH resume instruction.
409  auto *ResumeBB = CGF.getEHResumeBlock(/*cleanup=*/true);
410  auto *CleanupContBB = CGF.createBasicBlock("cleanup.cont");
411  CGF.Builder.CreateCondBr(CoroEnd, ResumeBB, CleanupContBB);
412  CGF.EmitBlock(CleanupContBB);
413  }
414  }
415 };
416 }
417 
418 namespace {
419 // Make sure to call coro.delete on scope exit.
420 struct CallCoroDelete final : public EHScopeStack::Cleanup {
421  Stmt *Deallocate;
422 
423  // Emit "if (coro.free(CoroId, CoroBegin)) Deallocate;"
424 
425  // Note: That deallocation will be emitted twice: once for a normal exit and
426  // once for exceptional exit. This usage is safe because Deallocate does not
427  // contain any declarations. The SubStmtBuilder::makeNewAndDeleteExpr()
428  // builds a single call to a deallocation function which is safe to emit
429  // multiple times.
430  void Emit(CodeGenFunction &CGF, Flags) override {
431  // Remember the current point, as we are going to emit deallocation code
432  // first to get to coro.free instruction that is an argument to a delete
433  // call.
434  BasicBlock *SaveInsertBlock = CGF.Builder.GetInsertBlock();
435 
436  auto *FreeBB = CGF.createBasicBlock("coro.free");
437  CGF.EmitBlock(FreeBB);
438  CGF.EmitStmt(Deallocate);
439 
440  auto *AfterFreeBB = CGF.createBasicBlock("after.coro.free");
441  CGF.EmitBlock(AfterFreeBB);
442 
443  // We should have captured coro.free from the emission of deallocate.
444  auto *CoroFree = CGF.CurCoro.Data->LastCoroFree;
445  if (!CoroFree) {
446  CGF.CGM.Error(Deallocate->getBeginLoc(),
447  "Deallocation expressoin does not refer to coro.free");
448  return;
449  }
450 
451  // Get back to the block we were originally and move coro.free there.
452  auto *InsertPt = SaveInsertBlock->getTerminator();
453  CoroFree->moveBefore(InsertPt);
454  CGF.Builder.SetInsertPoint(InsertPt);
455 
456  // Add if (auto *mem = coro.free) Deallocate;
457  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
458  auto *Cond = CGF.Builder.CreateICmpNE(CoroFree, NullPtr);
459  CGF.Builder.CreateCondBr(Cond, FreeBB, AfterFreeBB);
460 
461  // No longer need old terminator.
462  InsertPt->eraseFromParent();
463  CGF.Builder.SetInsertPoint(AfterFreeBB);
464  }
465  explicit CallCoroDelete(Stmt *DeallocStmt) : Deallocate(DeallocStmt) {}
466 };
467 }
468 
469 namespace {
470 struct GetReturnObjectManager {
471  CodeGenFunction &CGF;
472  CGBuilderTy &Builder;
473  const CoroutineBodyStmt &S;
474 
475  Address GroActiveFlag;
477 
478  GetReturnObjectManager(CodeGenFunction &CGF, const CoroutineBodyStmt &S)
479  : CGF(CGF), Builder(CGF.Builder), S(S), GroActiveFlag(Address::invalid()),
481 
482  // The gro variable has to outlive coroutine frame and coroutine promise, but,
483  // it can only be initialized after coroutine promise was created, thus, we
484  // split its emission in two parts. EmitGroAlloca emits an alloca and sets up
485  // cleanups. Later when coroutine promise is available we initialize the gro
486  // and sets the flag that the cleanup is now active.
487 
488  void EmitGroAlloca() {
489  auto *GroDeclStmt = dyn_cast<DeclStmt>(S.getResultDecl());
490  if (!GroDeclStmt) {
491  // If get_return_object returns void, no need to do an alloca.
492  return;
493  }
494 
495  auto *GroVarDecl = cast<VarDecl>(GroDeclStmt->getSingleDecl());
496 
497  // Set GRO flag that it is not initialized yet
498  GroActiveFlag =
499  CGF.CreateTempAlloca(Builder.getInt1Ty(), CharUnits::One(), "gro.active");
500  Builder.CreateStore(Builder.getFalse(), GroActiveFlag);
501 
502  GroEmission = CGF.EmitAutoVarAlloca(*GroVarDecl);
503 
504  // Remember the top of EHStack before emitting the cleanup.
505  auto old_top = CGF.EHStack.stable_begin();
506  CGF.EmitAutoVarCleanups(GroEmission);
507  auto top = CGF.EHStack.stable_begin();
508 
509  // Make the cleanup conditional on gro.active
510  for (auto b = CGF.EHStack.find(top), e = CGF.EHStack.find(old_top);
511  b != e; b++) {
512  if (auto *Cleanup = dyn_cast<EHCleanupScope>(&*b)) {
513  assert(!Cleanup->hasActiveFlag() && "cleanup already has active flag?");
514  Cleanup->setActiveFlag(GroActiveFlag);
515  Cleanup->setTestFlagInEHCleanup();
516  Cleanup->setTestFlagInNormalCleanup();
517  }
518  }
519  }
520 
521  void EmitGroInit() {
522  if (!GroActiveFlag.isValid()) {
523  // No Gro variable was allocated. Simply emit the call to
524  // get_return_object.
525  CGF.EmitStmt(S.getResultDecl());
526  return;
527  }
528 
529  CGF.EmitAutoVarInit(GroEmission);
530  Builder.CreateStore(Builder.getTrue(), GroActiveFlag);
531  }
532 };
533 }
534 
536  const CoroutineBodyStmt &S, Stmt *Body) {
537  CGF.EmitStmt(Body);
538  const bool CanFallthrough = CGF.Builder.GetInsertBlock();
539  if (CanFallthrough)
540  if (Stmt *OnFallthrough = S.getFallthroughHandler())
541  CGF.EmitStmt(OnFallthrough);
542 }
543 
545  auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
546  auto &TI = CGM.getContext().getTargetInfo();
547  unsigned NewAlign = TI.getNewAlign() / TI.getCharWidth();
548 
549  auto *EntryBB = Builder.GetInsertBlock();
550  auto *AllocBB = createBasicBlock("coro.alloc");
551  auto *InitBB = createBasicBlock("coro.init");
552  auto *FinalBB = createBasicBlock("coro.final");
553  auto *RetBB = createBasicBlock("coro.ret");
554 
555  auto *CoroId = Builder.CreateCall(
556  CGM.getIntrinsic(llvm::Intrinsic::coro_id),
557  {Builder.getInt32(NewAlign), NullPtr, NullPtr, NullPtr});
558  createCoroData(*this, CurCoro, CoroId);
559  CurCoro.Data->SuspendBB = RetBB;
560 
561  // Backend is allowed to elide memory allocations, to help it, emit
562  // auto mem = coro.alloc() ? 0 : ... allocation code ...;
563  auto *CoroAlloc = Builder.CreateCall(
564  CGM.getIntrinsic(llvm::Intrinsic::coro_alloc), {CoroId});
565 
566  Builder.CreateCondBr(CoroAlloc, AllocBB, InitBB);
567 
568  EmitBlock(AllocBB);
569  auto *AllocateCall = EmitScalarExpr(S.getAllocate());
570  auto *AllocOrInvokeContBB = Builder.GetInsertBlock();
571 
572  // Handle allocation failure if 'ReturnStmtOnAllocFailure' was provided.
573  if (auto *RetOnAllocFailure = S.getReturnStmtOnAllocFailure()) {
574  auto *RetOnFailureBB = createBasicBlock("coro.ret.on.failure");
575 
576  // See if allocation was successful.
577  auto *NullPtr = llvm::ConstantPointerNull::get(Int8PtrTy);
578  auto *Cond = Builder.CreateICmpNE(AllocateCall, NullPtr);
579  Builder.CreateCondBr(Cond, InitBB, RetOnFailureBB);
580 
581  // If not, return OnAllocFailure object.
582  EmitBlock(RetOnFailureBB);
583  EmitStmt(RetOnAllocFailure);
584  }
585  else {
586  Builder.CreateBr(InitBB);
587  }
588 
589  EmitBlock(InitBB);
590 
591  // Pass the result of the allocation to coro.begin.
592  auto *Phi = Builder.CreatePHI(VoidPtrTy, 2);
593  Phi->addIncoming(NullPtr, EntryBB);
594  Phi->addIncoming(AllocateCall, AllocOrInvokeContBB);
595  auto *CoroBegin = Builder.CreateCall(
596  CGM.getIntrinsic(llvm::Intrinsic::coro_begin), {CoroId, Phi});
597  CurCoro.Data->CoroBegin = CoroBegin;
598 
599  GetReturnObjectManager GroManager(*this, S);
600  GroManager.EmitGroAlloca();
601 
602  CurCoro.Data->CleanupJD = getJumpDestInCurrentScope(RetBB);
603  {
604  ParamReferenceReplacerRAII ParamReplacer(LocalDeclMap);
605  CodeGenFunction::RunCleanupsScope ResumeScope(*this);
606  EHStack.pushCleanup<CallCoroDelete>(NormalAndEHCleanup, S.getDeallocate());
607 
608  // Create parameter copies. We do it before creating a promise, since an
609  // evolution of coroutine TS may allow promise constructor to observe
610  // parameter copies.
611  for (auto *PM : S.getParamMoves()) {
612  EmitStmt(PM);
613  ParamReplacer.addCopy(cast<DeclStmt>(PM));
614  // TODO: if(CoroParam(...)) need to surround ctor and dtor
615  // for the copy, so that llvm can elide it if the copy is
616  // not needed.
617  }
618 
619  EmitStmt(S.getPromiseDeclStmt());
620 
621  Address PromiseAddr = GetAddrOfLocalVar(S.getPromiseDecl());
622  auto *PromiseAddrVoidPtr =
623  new llvm::BitCastInst(PromiseAddr.getPointer(), VoidPtrTy, "", CoroId);
624  // Update CoroId to refer to the promise. We could not do it earlier because
625  // promise local variable was not emitted yet.
626  CoroId->setArgOperand(1, PromiseAddrVoidPtr);
627 
628  // Now we have the promise, initialize the GRO
629  GroManager.EmitGroInit();
630 
631  EHStack.pushCleanup<CallCoroEnd>(EHCleanup);
632 
633  CurCoro.Data->CurrentAwaitKind = AwaitKind::Init;
634  CurCoro.Data->ExceptionHandler = S.getExceptionHandler();
635  EmitStmt(S.getInitSuspendStmt());
636  CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
637 
638  CurCoro.Data->CurrentAwaitKind = AwaitKind::Normal;
639 
640  if (CurCoro.Data->ExceptionHandler) {
641  // If we generated IR to record whether an exception was thrown from
642  // 'await_resume', then use that IR to determine whether the coroutine
643  // body should be skipped.
644  // If we didn't generate the IR (perhaps because 'await_resume' was marked
645  // as 'noexcept'), then we skip this check.
646  BasicBlock *ContBB = nullptr;
647  if (CurCoro.Data->ResumeEHVar) {
648  BasicBlock *BodyBB = createBasicBlock("coro.resumed.body");
649  ContBB = createBasicBlock("coro.resumed.cont");
650  Value *SkipBody = Builder.CreateFlagLoad(CurCoro.Data->ResumeEHVar,
651  "coro.resumed.eh");
652  Builder.CreateCondBr(SkipBody, ContBB, BodyBB);
653  EmitBlock(BodyBB);
654  }
655 
656  auto Loc = S.getBeginLoc();
657  CXXCatchStmt Catch(Loc, /*exDecl=*/nullptr,
658  CurCoro.Data->ExceptionHandler);
659  auto *TryStmt =
660  CXXTryStmt::Create(getContext(), Loc, S.getBody(), &Catch);
661 
662  EnterCXXTryStmt(*TryStmt);
663  emitBodyAndFallthrough(*this, S, TryStmt->getTryBlock());
664  ExitCXXTryStmt(*TryStmt);
665 
666  if (ContBB)
667  EmitBlock(ContBB);
668  }
669  else {
670  emitBodyAndFallthrough(*this, S, S.getBody());
671  }
672 
673  // See if we need to generate final suspend.
674  const bool CanFallthrough = Builder.GetInsertBlock();
675  const bool HasCoreturns = CurCoro.Data->CoreturnCount > 0;
676  if (CanFallthrough || HasCoreturns) {
677  EmitBlock(FinalBB);
678  CurCoro.Data->CurrentAwaitKind = AwaitKind::Final;
679  EmitStmt(S.getFinalSuspendStmt());
680  } else {
681  // We don't need FinalBB. Emit it to make sure the block is deleted.
682  EmitBlock(FinalBB, /*IsFinished=*/true);
683  }
684  }
685 
686  EmitBlock(RetBB);
687  // Emit coro.end before getReturnStmt (and parameter destructors), since
688  // resume and destroy parts of the coroutine should not include them.
689  llvm::Function *CoroEnd = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
690  Builder.CreateCall(CoroEnd, {NullPtr, Builder.getFalse()});
691 
692  if (Stmt *Ret = S.getReturnStmt())
693  EmitStmt(Ret);
694 }
695 
696 // Emit coroutine intrinsic and patch up arguments of the token type.
698  unsigned int IID) {
700  switch (IID) {
701  default:
702  break;
703  // The coro.frame builtin is replaced with an SSA value of the coro.begin
704  // intrinsic.
705  case llvm::Intrinsic::coro_frame: {
706  if (CurCoro.Data && CurCoro.Data->CoroBegin) {
707  return RValue::get(CurCoro.Data->CoroBegin);
708  }
709  CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_begin "
710  "has been used earlier in this function");
711  auto NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
712  return RValue::get(NullPtr);
713  }
714  // The following three intrinsics take a token parameter referring to a token
715  // returned by earlier call to @llvm.coro.id. Since we cannot represent it in
716  // builtins, we patch it up here.
717  case llvm::Intrinsic::coro_alloc:
718  case llvm::Intrinsic::coro_begin:
719  case llvm::Intrinsic::coro_free: {
720  if (CurCoro.Data && CurCoro.Data->CoroId) {
721  Args.push_back(CurCoro.Data->CoroId);
722  break;
723  }
724  CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_id has"
725  " been used earlier in this function");
726  // Fallthrough to the next case to add TokenNone as the first argument.
727  LLVM_FALLTHROUGH;
728  }
729  // @llvm.coro.suspend takes a token parameter. Add token 'none' as the first
730  // argument.
731  case llvm::Intrinsic::coro_suspend:
732  Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
733  break;
734  }
735  for (const Expr *Arg : E->arguments())
736  Args.push_back(EmitScalarExpr(Arg));
737 
738  llvm::Function *F = CGM.getIntrinsic(IID);
739  llvm::CallInst *Call = Builder.CreateCall(F, Args);
740 
741  // Note: The following code is to enable to emit coro.id and coro.begin by
742  // hand to experiment with coroutines in C.
743  // If we see @llvm.coro.id remember it in the CoroData. We will update
744  // coro.alloc, coro.begin and coro.free intrinsics to refer to it.
745  if (IID == llvm::Intrinsic::coro_id) {
746  createCoroData(*this, CurCoro, Call, E);
747  }
748  else if (IID == llvm::Intrinsic::coro_begin) {
749  if (CurCoro.Data)
750  CurCoro.Data->CoroBegin = Call;
751  }
752  else if (IID == llvm::Intrinsic::coro_free) {
753  // Remember the last coro_free as we need it to build the conditional
754  // deletion of the coroutine frame.
755  if (CurCoro.Data)
756  CurCoro.Data->LastCoroFree = Call;
757  }
758  return RValue::get(Call);
759 }
Expr * getReadyExpr() const
Definition: ExprCXX.h:4576
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:812
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:154
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:193
ArrayRef< Stmt const * > getParamMoves() const
Definition: StmtCXX.h:417
child_range children()
Definition: Stmt.cpp:212
static CompoundStmt * Create(const ASTContext &C, ArrayRef< Stmt *> Stmts, SourceLocation LB, SourceLocation RB)
Definition: Stmt.cpp:307
b
Definition: emmintrin.h:321
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:4574
Expr * getCommonExpr() const
Definition: ExprCXX.h:4569
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:105
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:57
AutoVarEmission EmitAutoVarAlloca(const VarDecl &var)
EmitAutoVarAlloca - Emit the alloca and debug information for a local variable.
Definition: CGDecl.cpp:1379
Represents a prototype with parameter type info, e.g.
Definition: Type.h:3704
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:1658
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:1219
CodeGenFunction::JumpDest FinalJD
Definition: CGCoroutine.cpp:62
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:1196
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:4580
arg_range arguments()
Definition: Expr.h:2712
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:215
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:4696
Expr * getOperand() const
Retrieve the operand of the &#39;co_return&#39; statement.
Definition: StmtCXX.h:480
const Decl * getSingleDecl() const
Definition: Stmt.h:1211
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:1209
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:1971
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:4609
void EmitBlock(llvm::BasicBlock *BB, bool IsFinished=false)
EmitBlock - Emit the given block.
Definition: CGStmt.cpp:450
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:4522
Expr * getResumeExpr() const
Definition: ExprCXX.h:4584
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:6610
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:2518
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:1143
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:1043
LValue - This represents an lvalue references.
Definition: CGValue.h:166
SourceLocation getBeginLoc() const LLVM_READONLY
Definition: Expr.cpp:1499
Information for lazily generating a cleanup.
Definition: EHScopeStack.h:146
Stmt * getFinalSuspendStmt() const
Definition: StmtCXX.h:392