clang  7.0.0svn
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->getLocStart(),
97  "only one __builtin_coro_id can be used in a function");
98  else if (CoroIdExpr)
99  CGF.CGM.Error(CoroIdExpr->getLocStart(),
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.
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 // Emit suspend expression which roughly looks like:
134 //
135 // auto && x = CommonExpr();
136 // if (!x.await_ready()) {
137 // llvm_coro_save();
138 // x.await_suspend(...); (*)
139 // llvm_coro_suspend(); (**)
140 // }
141 // x.await_resume();
142 //
143 // where the result of the entire expression is the result of x.await_resume()
144 //
145 // (*) If x.await_suspend return type is bool, it allows to veto a suspend:
146 // if (x.await_suspend(...))
147 // llvm_coro_suspend();
148 //
149 // (**) llvm_coro_suspend() encodes three possible continuations as
150 // a switch instruction:
151 //
152 // %where-to = call i8 @llvm.coro.suspend(...)
153 // switch i8 %where-to, label %coro.ret [ ; jump to epilogue to suspend
154 // i8 0, label %yield.ready ; go here when resumed
155 // i8 1, label %yield.cleanup ; go here when destroyed
156 // ]
157 //
158 // See llvm's docs/Coroutines.rst for more details.
159 //
160 namespace {
161  struct LValueOrRValue {
162  LValue LV;
163  RValue RV;
164  };
165 }
166 static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Coro,
167  CoroutineSuspendExpr const &S,
168  AwaitKind Kind, AggValueSlot aggSlot,
169  bool ignoreResult, bool forLValue) {
170  auto *E = S.getCommonExpr();
171 
172  auto Binder =
174  auto UnbindOnExit = llvm::make_scope_exit([&] { Binder.unbind(CGF); });
175 
176  auto Prefix = buildSuspendPrefixStr(Coro, Kind);
177  BasicBlock *ReadyBlock = CGF.createBasicBlock(Prefix + Twine(".ready"));
178  BasicBlock *SuspendBlock = CGF.createBasicBlock(Prefix + Twine(".suspend"));
179  BasicBlock *CleanupBlock = CGF.createBasicBlock(Prefix + Twine(".cleanup"));
180 
181  // If expression is ready, no need to suspend.
182  CGF.EmitBranchOnBoolExpr(S.getReadyExpr(), ReadyBlock, SuspendBlock, 0);
183 
184  // Otherwise, emit suspend logic.
185  CGF.EmitBlock(SuspendBlock);
186 
187  auto &Builder = CGF.Builder;
188  llvm::Function *CoroSave = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_save);
189  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.CGM.Int8PtrTy);
190  auto *SaveCall = Builder.CreateCall(CoroSave, {NullPtr});
191 
192  auto *SuspendRet = CGF.EmitScalarExpr(S.getSuspendExpr());
193  if (SuspendRet != nullptr && SuspendRet->getType()->isIntegerTy(1)) {
194  // Veto suspension if requested by bool returning await_suspend.
195  BasicBlock *RealSuspendBlock =
196  CGF.createBasicBlock(Prefix + Twine(".suspend.bool"));
197  CGF.Builder.CreateCondBr(SuspendRet, RealSuspendBlock, ReadyBlock);
198  SuspendBlock = RealSuspendBlock;
199  CGF.EmitBlock(RealSuspendBlock);
200  }
201 
202  // Emit the suspend point.
203  const bool IsFinalSuspend = (Kind == AwaitKind::Final);
204  llvm::Function *CoroSuspend =
205  CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_suspend);
206  auto *SuspendResult = Builder.CreateCall(
207  CoroSuspend, {SaveCall, Builder.getInt1(IsFinalSuspend)});
208 
209  // Create a switch capturing three possible continuations.
210  auto *Switch = Builder.CreateSwitch(SuspendResult, Coro.SuspendBB, 2);
211  Switch->addCase(Builder.getInt8(0), ReadyBlock);
212  Switch->addCase(Builder.getInt8(1), CleanupBlock);
213 
214  // Emit cleanup for this suspend point.
215  CGF.EmitBlock(CleanupBlock);
217 
218  // Emit await_resume expression.
219  CGF.EmitBlock(ReadyBlock);
220  CXXTryStmt *TryStmt = nullptr;
221  if (Coro.ExceptionHandler && Kind == AwaitKind::Init) {
222  Coro.ResumeEHVar =
223  CGF.CreateTempAlloca(Builder.getInt1Ty(), Prefix + Twine("resume.eh"));
224  Builder.CreateFlagStore(true, Coro.ResumeEHVar);
225 
226  auto Loc = S.getResumeExpr()->getExprLoc();
227  auto *Catch = new (CGF.getContext())
228  CXXCatchStmt(Loc, /*exDecl=*/nullptr, Coro.ExceptionHandler);
229  auto *TryBody =
230  CompoundStmt::Create(CGF.getContext(), S.getResumeExpr(), Loc, Loc);
231  TryStmt = CXXTryStmt::Create(CGF.getContext(), Loc, TryBody, Catch);
232  CGF.EnterCXXTryStmt(*TryStmt);
233  }
234 
235  LValueOrRValue Res;
236  if (forLValue)
237  Res.LV = CGF.EmitLValue(S.getResumeExpr());
238  else
239  Res.RV = CGF.EmitAnyExpr(S.getResumeExpr(), aggSlot, ignoreResult);
240 
241  if (TryStmt) {
242  Builder.CreateFlagStore(false, Coro.ResumeEHVar);
243  CGF.ExitCXXTryStmt(*TryStmt);
244  }
245 
246  return Res;
247 }
248 
250  AggValueSlot aggSlot,
251  bool ignoreResult) {
252  return emitSuspendExpression(*this, *CurCoro.Data, E,
253  CurCoro.Data->CurrentAwaitKind, aggSlot,
254  ignoreResult, /*forLValue*/false).RV;
255 }
257  AggValueSlot aggSlot,
258  bool ignoreResult) {
259  return emitSuspendExpression(*this, *CurCoro.Data, E, AwaitKind::Yield,
260  aggSlot, ignoreResult, /*forLValue*/false).RV;
261 }
262 
264  ++CurCoro.Data->CoreturnCount;
265  const Expr *RV = S.getOperand();
266  if (RV && RV->getType()->isVoidType()) {
267  // Make sure to evaluate the expression of a co_return with a void
268  // expression for side effects.
269  RunCleanupsScope cleanupScope(*this);
270  EmitIgnoredExpr(RV);
271  }
272  EmitStmt(S.getPromiseCall());
273  EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
274 }
275 
276 
277 #ifndef NDEBUG
279  const CoroutineSuspendExpr *E) {
280  const auto *RE = E->getResumeExpr();
281  // Is it possible for RE to be a CXXBindTemporaryExpr wrapping
282  // a MemberCallExpr?
283  assert(isa<CallExpr>(RE) && "unexpected suspend expression type");
284  return cast<CallExpr>(RE)->getCallReturnType(Ctx);
285 }
286 #endif
287 
288 LValue
290  assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
291  "Can't have a scalar return unless the return type is a "
292  "reference type!");
293  return emitSuspendExpression(*this, *CurCoro.Data, *E,
294  CurCoro.Data->CurrentAwaitKind, AggValueSlot::ignored(),
295  /*ignoreResult*/false, /*forLValue*/true).LV;
296 }
297 
298 LValue
300  assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
301  "Can't have a scalar return unless the return type is a "
302  "reference type!");
303  return emitSuspendExpression(*this, *CurCoro.Data, *E,
304  AwaitKind::Yield, AggValueSlot::ignored(),
305  /*ignoreResult*/false, /*forLValue*/true).LV;
306 }
307 
308 // Hunts for the parameter reference in the parameter copy/move declaration.
309 namespace {
310 struct GetParamRef : public StmtVisitor<GetParamRef> {
311 public:
312  DeclRefExpr *Expr = nullptr;
313  GetParamRef() {}
314  void VisitDeclRefExpr(DeclRefExpr *E) {
315  assert(Expr == nullptr && "multilple declref in param move");
316  Expr = E;
317  }
318  void VisitStmt(Stmt *S) {
319  for (auto *C : S->children()) {
320  if (C)
321  Visit(C);
322  }
323  }
324 };
325 }
326 
327 // This class replaces references to parameters to their copies by changing
328 // the addresses in CGF.LocalDeclMap and restoring back the original values in
329 // its destructor.
330 
331 namespace {
332  struct ParamReferenceReplacerRAII {
333  CodeGenFunction::DeclMapTy SavedLocals;
334  CodeGenFunction::DeclMapTy& LocalDeclMap;
335 
336  ParamReferenceReplacerRAII(CodeGenFunction::DeclMapTy &LocalDeclMap)
337  : LocalDeclMap(LocalDeclMap) {}
338 
339  void addCopy(DeclStmt const *PM) {
340  // Figure out what param it refers to.
341 
342  assert(PM->isSingleDecl());
343  VarDecl const*VD = static_cast<VarDecl const*>(PM->getSingleDecl());
344  Expr const *InitExpr = VD->getInit();
345  GetParamRef Visitor;
346  Visitor.Visit(const_cast<Expr*>(InitExpr));
347  assert(Visitor.Expr);
348  DeclRefExpr *DREOrig = Visitor.Expr;
349  auto *PD = DREOrig->getDecl();
350 
351  auto it = LocalDeclMap.find(PD);
352  assert(it != LocalDeclMap.end() && "parameter is not found");
353  SavedLocals.insert({ PD, it->second });
354 
355  auto copyIt = LocalDeclMap.find(VD);
356  assert(copyIt != LocalDeclMap.end() && "parameter copy is not found");
357  it->second = copyIt->getSecond();
358  }
359 
360  ~ParamReferenceReplacerRAII() {
361  for (auto&& SavedLocal : SavedLocals) {
362  LocalDeclMap.insert({SavedLocal.first, SavedLocal.second});
363  }
364  }
365  };
366 }
367 
368 // For WinEH exception representation backend needs to know what funclet coro.end
369 // belongs to. That information is passed in a funclet bundle.
373 
374  if (llvm::Instruction *EHPad = CGF.CurrentFuncletPad)
375  BundleList.emplace_back("funclet", EHPad);
376 
377  return BundleList;
378 }
379 
380 namespace {
381 // We will insert coro.end to cut any of the destructors for objects that
382 // do not need to be destroyed once the coroutine is resumed.
383 // See llvm/docs/Coroutines.rst for more details about coro.end.
384 struct CallCoroEnd final : public EHScopeStack::Cleanup {
385  void Emit(CodeGenFunction &CGF, Flags flags) override {
386  auto &CGM = CGF.CGM;
387  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
388  llvm::Function *CoroEndFn = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
389  // See if we have a funclet bundle to associate coro.end with. (WinEH)
390  auto Bundles = getBundlesForCoroEnd(CGF);
391  auto *CoroEnd = CGF.Builder.CreateCall(
392  CoroEndFn, {NullPtr, CGF.Builder.getTrue()}, Bundles);
393  if (Bundles.empty()) {
394  // Otherwise, (landingpad model), create a conditional branch that leads
395  // either to a cleanup block or a block with EH resume instruction.
396  auto *ResumeBB = CGF.getEHResumeBlock(/*cleanup=*/true);
397  auto *CleanupContBB = CGF.createBasicBlock("cleanup.cont");
398  CGF.Builder.CreateCondBr(CoroEnd, ResumeBB, CleanupContBB);
399  CGF.EmitBlock(CleanupContBB);
400  }
401  }
402 };
403 }
404 
405 namespace {
406 // Make sure to call coro.delete on scope exit.
407 struct CallCoroDelete final : public EHScopeStack::Cleanup {
408  Stmt *Deallocate;
409 
410  // Emit "if (coro.free(CoroId, CoroBegin)) Deallocate;"
411 
412  // Note: That deallocation will be emitted twice: once for a normal exit and
413  // once for exceptional exit. This usage is safe because Deallocate does not
414  // contain any declarations. The SubStmtBuilder::makeNewAndDeleteExpr()
415  // builds a single call to a deallocation function which is safe to emit
416  // multiple times.
417  void Emit(CodeGenFunction &CGF, Flags) override {
418  // Remember the current point, as we are going to emit deallocation code
419  // first to get to coro.free instruction that is an argument to a delete
420  // call.
421  BasicBlock *SaveInsertBlock = CGF.Builder.GetInsertBlock();
422 
423  auto *FreeBB = CGF.createBasicBlock("coro.free");
424  CGF.EmitBlock(FreeBB);
425  CGF.EmitStmt(Deallocate);
426 
427  auto *AfterFreeBB = CGF.createBasicBlock("after.coro.free");
428  CGF.EmitBlock(AfterFreeBB);
429 
430  // We should have captured coro.free from the emission of deallocate.
431  auto *CoroFree = CGF.CurCoro.Data->LastCoroFree;
432  if (!CoroFree) {
433  CGF.CGM.Error(Deallocate->getLocStart(),
434  "Deallocation expressoin does not refer to coro.free");
435  return;
436  }
437 
438  // Get back to the block we were originally and move coro.free there.
439  auto *InsertPt = SaveInsertBlock->getTerminator();
440  CoroFree->moveBefore(InsertPt);
441  CGF.Builder.SetInsertPoint(InsertPt);
442 
443  // Add if (auto *mem = coro.free) Deallocate;
444  auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
445  auto *Cond = CGF.Builder.CreateICmpNE(CoroFree, NullPtr);
446  CGF.Builder.CreateCondBr(Cond, FreeBB, AfterFreeBB);
447 
448  // No longer need old terminator.
449  InsertPt->eraseFromParent();
450  CGF.Builder.SetInsertPoint(AfterFreeBB);
451  }
452  explicit CallCoroDelete(Stmt *DeallocStmt) : Deallocate(DeallocStmt) {}
453 };
454 }
455 
456 namespace {
457 struct GetReturnObjectManager {
458  CodeGenFunction &CGF;
459  CGBuilderTy &Builder;
460  const CoroutineBodyStmt &S;
461 
462  Address GroActiveFlag;
464 
465  GetReturnObjectManager(CodeGenFunction &CGF, const CoroutineBodyStmt &S)
466  : CGF(CGF), Builder(CGF.Builder), S(S), GroActiveFlag(Address::invalid()),
468 
469  // The gro variable has to outlive coroutine frame and coroutine promise, but,
470  // it can only be initialized after coroutine promise was created, thus, we
471  // split its emission in two parts. EmitGroAlloca emits an alloca and sets up
472  // cleanups. Later when coroutine promise is available we initialize the gro
473  // and sets the flag that the cleanup is now active.
474 
475  void EmitGroAlloca() {
476  auto *GroDeclStmt = dyn_cast<DeclStmt>(S.getResultDecl());
477  if (!GroDeclStmt) {
478  // If get_return_object returns void, no need to do an alloca.
479  return;
480  }
481 
482  auto *GroVarDecl = cast<VarDecl>(GroDeclStmt->getSingleDecl());
483 
484  // Set GRO flag that it is not initialized yet
485  GroActiveFlag =
486  CGF.CreateTempAlloca(Builder.getInt1Ty(), CharUnits::One(), "gro.active");
487  Builder.CreateStore(Builder.getFalse(), GroActiveFlag);
488 
489  GroEmission = CGF.EmitAutoVarAlloca(*GroVarDecl);
490 
491  // Remember the top of EHStack before emitting the cleanup.
492  auto old_top = CGF.EHStack.stable_begin();
493  CGF.EmitAutoVarCleanups(GroEmission);
494  auto top = CGF.EHStack.stable_begin();
495 
496  // Make the cleanup conditional on gro.active
497  for (auto b = CGF.EHStack.find(top), e = CGF.EHStack.find(old_top);
498  b != e; b++) {
499  if (auto *Cleanup = dyn_cast<EHCleanupScope>(&*b)) {
500  assert(!Cleanup->hasActiveFlag() && "cleanup already has active flag?");
501  Cleanup->setActiveFlag(GroActiveFlag);
502  Cleanup->setTestFlagInEHCleanup();
503  Cleanup->setTestFlagInNormalCleanup();
504  }
505  }
506  }
507 
508  void EmitGroInit() {
509  if (!GroActiveFlag.isValid()) {
510  // No Gro variable was allocated. Simply emit the call to
511  // get_return_object.
512  CGF.EmitStmt(S.getResultDecl());
513  return;
514  }
515 
516  CGF.EmitAutoVarInit(GroEmission);
517  Builder.CreateStore(Builder.getTrue(), GroActiveFlag);
518  }
519 };
520 }
521 
523  const CoroutineBodyStmt &S, Stmt *Body) {
524  CGF.EmitStmt(Body);
525  const bool CanFallthrough = CGF.Builder.GetInsertBlock();
526  if (CanFallthrough)
527  if (Stmt *OnFallthrough = S.getFallthroughHandler())
528  CGF.EmitStmt(OnFallthrough);
529 }
530 
532  auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
533  auto &TI = CGM.getContext().getTargetInfo();
534  unsigned NewAlign = TI.getNewAlign() / TI.getCharWidth();
535 
536  auto *EntryBB = Builder.GetInsertBlock();
537  auto *AllocBB = createBasicBlock("coro.alloc");
538  auto *InitBB = createBasicBlock("coro.init");
539  auto *FinalBB = createBasicBlock("coro.final");
540  auto *RetBB = createBasicBlock("coro.ret");
541 
542  auto *CoroId = Builder.CreateCall(
543  CGM.getIntrinsic(llvm::Intrinsic::coro_id),
544  {Builder.getInt32(NewAlign), NullPtr, NullPtr, NullPtr});
545  createCoroData(*this, CurCoro, CoroId);
546  CurCoro.Data->SuspendBB = RetBB;
547 
548  // Backend is allowed to elide memory allocations, to help it, emit
549  // auto mem = coro.alloc() ? 0 : ... allocation code ...;
550  auto *CoroAlloc = Builder.CreateCall(
551  CGM.getIntrinsic(llvm::Intrinsic::coro_alloc), {CoroId});
552 
553  Builder.CreateCondBr(CoroAlloc, AllocBB, InitBB);
554 
555  EmitBlock(AllocBB);
556  auto *AllocateCall = EmitScalarExpr(S.getAllocate());
557  auto *AllocOrInvokeContBB = Builder.GetInsertBlock();
558 
559  // Handle allocation failure if 'ReturnStmtOnAllocFailure' was provided.
560  if (auto *RetOnAllocFailure = S.getReturnStmtOnAllocFailure()) {
561  auto *RetOnFailureBB = createBasicBlock("coro.ret.on.failure");
562 
563  // See if allocation was successful.
564  auto *NullPtr = llvm::ConstantPointerNull::get(Int8PtrTy);
565  auto *Cond = Builder.CreateICmpNE(AllocateCall, NullPtr);
566  Builder.CreateCondBr(Cond, InitBB, RetOnFailureBB);
567 
568  // If not, return OnAllocFailure object.
569  EmitBlock(RetOnFailureBB);
570  EmitStmt(RetOnAllocFailure);
571  }
572  else {
573  Builder.CreateBr(InitBB);
574  }
575 
576  EmitBlock(InitBB);
577 
578  // Pass the result of the allocation to coro.begin.
579  auto *Phi = Builder.CreatePHI(VoidPtrTy, 2);
580  Phi->addIncoming(NullPtr, EntryBB);
581  Phi->addIncoming(AllocateCall, AllocOrInvokeContBB);
582  auto *CoroBegin = Builder.CreateCall(
583  CGM.getIntrinsic(llvm::Intrinsic::coro_begin), {CoroId, Phi});
584  CurCoro.Data->CoroBegin = CoroBegin;
585 
586  GetReturnObjectManager GroManager(*this, S);
587  GroManager.EmitGroAlloca();
588 
589  CurCoro.Data->CleanupJD = getJumpDestInCurrentScope(RetBB);
590  {
591  ParamReferenceReplacerRAII ParamReplacer(LocalDeclMap);
592  CodeGenFunction::RunCleanupsScope ResumeScope(*this);
593  EHStack.pushCleanup<CallCoroDelete>(NormalAndEHCleanup, S.getDeallocate());
594 
595  // Create parameter copies. We do it before creating a promise, since an
596  // evolution of coroutine TS may allow promise constructor to observe
597  // parameter copies.
598  for (auto *PM : S.getParamMoves()) {
599  EmitStmt(PM);
600  ParamReplacer.addCopy(cast<DeclStmt>(PM));
601  // TODO: if(CoroParam(...)) need to surround ctor and dtor
602  // for the copy, so that llvm can elide it if the copy is
603  // not needed.
604  }
605 
606  EmitStmt(S.getPromiseDeclStmt());
607 
608  Address PromiseAddr = GetAddrOfLocalVar(S.getPromiseDecl());
609  auto *PromiseAddrVoidPtr =
610  new llvm::BitCastInst(PromiseAddr.getPointer(), VoidPtrTy, "", CoroId);
611  // Update CoroId to refer to the promise. We could not do it earlier because
612  // promise local variable was not emitted yet.
613  CoroId->setArgOperand(1, PromiseAddrVoidPtr);
614 
615  // Now we have the promise, initialize the GRO
616  GroManager.EmitGroInit();
617 
618  EHStack.pushCleanup<CallCoroEnd>(EHCleanup);
619 
620  CurCoro.Data->CurrentAwaitKind = AwaitKind::Init;
621  CurCoro.Data->ExceptionHandler = S.getExceptionHandler();
622  EmitStmt(S.getInitSuspendStmt());
623  CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
624 
625  CurCoro.Data->CurrentAwaitKind = AwaitKind::Normal;
626 
627  if (CurCoro.Data->ExceptionHandler) {
628  BasicBlock *BodyBB = createBasicBlock("coro.resumed.body");
629  BasicBlock *ContBB = createBasicBlock("coro.resumed.cont");
630  Value *SkipBody =
631  Builder.CreateFlagLoad(CurCoro.Data->ResumeEHVar, "coro.resumed.eh");
632  Builder.CreateCondBr(SkipBody, ContBB, BodyBB);
633  EmitBlock(BodyBB);
634 
635  auto Loc = S.getLocStart();
636  CXXCatchStmt Catch(Loc, /*exDecl=*/nullptr,
637  CurCoro.Data->ExceptionHandler);
638  auto *TryStmt =
639  CXXTryStmt::Create(getContext(), Loc, S.getBody(), &Catch);
640 
641  EnterCXXTryStmt(*TryStmt);
642  emitBodyAndFallthrough(*this, S, TryStmt->getTryBlock());
643  ExitCXXTryStmt(*TryStmt);
644 
645  EmitBlock(ContBB);
646  }
647  else {
648  emitBodyAndFallthrough(*this, S, S.getBody());
649  }
650 
651  // See if we need to generate final suspend.
652  const bool CanFallthrough = Builder.GetInsertBlock();
653  const bool HasCoreturns = CurCoro.Data->CoreturnCount > 0;
654  if (CanFallthrough || HasCoreturns) {
655  EmitBlock(FinalBB);
656  CurCoro.Data->CurrentAwaitKind = AwaitKind::Final;
657  EmitStmt(S.getFinalSuspendStmt());
658  } else {
659  // We don't need FinalBB. Emit it to make sure the block is deleted.
660  EmitBlock(FinalBB, /*IsFinished=*/true);
661  }
662  }
663 
664  EmitBlock(RetBB);
665  // Emit coro.end before getReturnStmt (and parameter destructors), since
666  // resume and destroy parts of the coroutine should not include them.
667  llvm::Function *CoroEnd = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
668  Builder.CreateCall(CoroEnd, {NullPtr, Builder.getFalse()});
669 
670  if (Stmt *Ret = S.getReturnStmt())
671  EmitStmt(Ret);
672 }
673 
674 // Emit coroutine intrinsic and patch up arguments of the token type.
676  unsigned int IID) {
678  switch (IID) {
679  default:
680  break;
681  // The coro.frame builtin is replaced with an SSA value of the coro.begin
682  // intrinsic.
683  case llvm::Intrinsic::coro_frame: {
684  if (CurCoro.Data && CurCoro.Data->CoroBegin) {
685  return RValue::get(CurCoro.Data->CoroBegin);
686  }
687  CGM.Error(E->getLocStart(), "this builtin expect that __builtin_coro_begin "
688  "has been used earlier in this function");
689  auto NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
690  return RValue::get(NullPtr);
691  }
692  // The following three intrinsics take a token parameter referring to a token
693  // returned by earlier call to @llvm.coro.id. Since we cannot represent it in
694  // builtins, we patch it up here.
695  case llvm::Intrinsic::coro_alloc:
696  case llvm::Intrinsic::coro_begin:
697  case llvm::Intrinsic::coro_free: {
698  if (CurCoro.Data && CurCoro.Data->CoroId) {
699  Args.push_back(CurCoro.Data->CoroId);
700  break;
701  }
702  CGM.Error(E->getLocStart(), "this builtin expect that __builtin_coro_id has"
703  " been used earlier in this function");
704  // Fallthrough to the next case to add TokenNone as the first argument.
705  LLVM_FALLTHROUGH;
706  }
707  // @llvm.coro.suspend takes a token parameter. Add token 'none' as the first
708  // argument.
709  case llvm::Intrinsic::coro_suspend:
710  Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
711  break;
712  }
713  for (auto &Arg : E->arguments())
714  Args.push_back(EmitScalarExpr(Arg));
715 
716  llvm::Value *F = CGM.getIntrinsic(IID);
717  llvm::CallInst *Call = Builder.CreateCall(F, Args);
718 
719  // Note: The following code is to enable to emit coro.id and coro.begin by
720  // hand to experiment with coroutines in C.
721  // If we see @llvm.coro.id remember it in the CoroData. We will update
722  // coro.alloc, coro.begin and coro.free intrinsics to refer to it.
723  if (IID == llvm::Intrinsic::coro_id) {
724  createCoroData(*this, CurCoro, Call, E);
725  }
726  else if (IID == llvm::Intrinsic::coro_begin) {
727  if (CurCoro.Data)
728  CurCoro.Data->CoroBegin = Call;
729  }
730  else if (IID == llvm::Intrinsic::coro_free) {
731  // Remember the last coro_free as we need it to build the conditional
732  // deletion of the coroutine frame.
733  if (CurCoro.Data)
734  CurCoro.Data->LastCoroFree = Call;
735  }
736  return RValue::get(Call);
737 }
Expr * getReadyExpr() const
Definition: ExprCXX.h:4277
void EmitCoroutineBody(const CoroutineBodyStmt &S)
A (possibly-)qualified type.
Definition: Type.h:654
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
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...
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:150
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:227
static CompoundStmt * Create(const ASTContext &C, ArrayRef< Stmt *> Stmts, SourceLocation LB, SourceLocation RB)
Definition: Stmt.cpp:317
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:4275
Expr * getCommonExpr() const
Definition: ExprCXX.h:4270
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:1045
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)
Expr - This represents one expression.
Definition: Expr.h:106
void EmitAutoVarInit(const AutoVarEmission &emission)
Definition: CGDecl.cpp:1325
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:128
SourceLocation getLocStart() const LLVM_READONLY
Definition: StmtCXX.h:403
ValueDecl * getDecl()
Definition: Expr.h:1057
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:499
An aggregate value slot.
Definition: CGValue.h:437
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:4281
arg_range arguments()
Definition: Expr.h:2336
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:491
Represents a &#39;co_yield&#39; expression.
Definition: ExprCXX.h:4391
Expr * getOperand() const
Retrieve the operand of the &#39;co_return&#39; statement.
Definition: StmtCXX.h:456
const Decl * getSingleDecl() const
Definition: Stmt.h:516
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:512
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:1564
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:4308
SourceLocation getLocStart() const LLVM_READONLY
Definition: Expr.cpp:1327
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:4223
Expr * getResumeExpr() const
Definition: ExprCXX.h:4285
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:6275
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:1199
CallExpr - Represents a function call (C99 6.5.2.2, C++ [expr.call]).
Definition: Expr.h:2242
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:972
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:1039
LValue - This represents an lvalue references.
Definition: CGValue.h:167
Information for lazily generating a cleanup.
Definition: EHScopeStack.h:147
Stmt * getFinalSuspendStmt() const
Definition: StmtCXX.h:374