1 //===----- CGCoroutine.cpp - Emit LLVM Code for C++ coroutines ------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This contains code dealing with C++ code generation of coroutines.
12 //===----------------------------------------------------------------------===//
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"
20 using namespace clang;
21 using namespace CodeGen;
24 using llvm::BasicBlock;
27 enum class AwaitKind { Init, Normal, Yield, Final };
28 static constexpr llvm::StringLiteral AwaitKindStr[] = {"init", "await", "yield",
32 struct clang::CodeGen::CGCoroData {
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;
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;
44 // A branch to this block is emitted when coroutine needs to suspend.
45 llvm::BasicBlock *SuspendBB = nullptr;
47 // Stores the jump destination just before the coroutine memory is freed.
48 // This is the destination that every suspend point jumps to for the cleanup
50 CodeGenFunction::JumpDest CleanupJD;
52 // Stores the jump destination just before the final suspend. The co_return
53 // statements jumps to this point after calling return_xxx promise member.
54 CodeGenFunction::JumpDest FinalJD;
56 // Stores the llvm.coro.id emitted in the function so that we can supply it
57 // as the first argument to coro.begin, coro.alloc and coro.free intrinsics.
58 // Note: llvm.coro.id returns a token that cannot be directly expressed in a
60 llvm::CallInst *CoroId = nullptr;
62 // Stores the llvm.coro.begin emitted in the function so that we can replace
63 // all coro.frame intrinsics with direct SSA value of coro.begin that returns
64 // the address of the coroutine frame of the current coroutine.
65 llvm::CallInst *CoroBegin = nullptr;
67 // Stores the last emitted coro.free for the deallocate expressions, we use it
68 // to wrap dealloc code with if(auto mem = coro.free) dealloc(mem).
69 llvm::CallInst *LastCoroFree = nullptr;
71 // If coro.id came from the builtin, remember the expression to give better
72 // diagnostic. If CoroIdExpr is nullptr, the coro.id was created by
74 CallExpr const *CoroIdExpr = nullptr;
77 // Defining these here allows to keep CGCoroData private to this file.
78 clang::CodeGen::CodeGenFunction::CGCoroInfo::CGCoroInfo() {}
79 CodeGenFunction::CGCoroInfo::~CGCoroInfo() {}
81 static void createCoroData(CodeGenFunction &CGF,
82 CodeGenFunction::CGCoroInfo &CurCoro,
83 llvm::CallInst *CoroId,
84 CallExpr const *CoroIdExpr = nullptr) {
86 if (CurCoro.Data->CoroIdExpr)
87 CGF.CGM.Error(CoroIdExpr->getLocStart(),
88 "only one __builtin_coro_id can be used in a function");
90 CGF.CGM.Error(CoroIdExpr->getLocStart(),
91 "__builtin_coro_id shall not be used in a C++ coroutine");
93 llvm_unreachable("EmitCoroutineBodyStatement called twice?");
98 CurCoro.Data = std::unique_ptr<CGCoroData>(new CGCoroData);
99 CurCoro.Data->CoroId = CoroId;
100 CurCoro.Data->CoroIdExpr = CoroIdExpr;
103 // Synthesize a pretty name for a suspend point.
104 static SmallString<32> buildSuspendPrefixStr(CGCoroData &Coro, AwaitKind Kind) {
107 case AwaitKind::Init:
108 case AwaitKind::Final:
110 case AwaitKind::Normal:
111 No = ++Coro.AwaitNum;
113 case AwaitKind::Yield:
114 No = ++Coro.YieldNum;
117 SmallString<32> Prefix(AwaitKindStr[static_cast<unsigned>(Kind)]);
119 Twine(No).toVector(Prefix);
124 // Emit suspend expression which roughly looks like:
126 // auto && x = CommonExpr();
127 // if (!x.await_ready()) {
129 // x.await_suspend(...); (*)
130 // llvm_coro_suspend(); (**)
134 // where the result of the entire expression is the result of x.await_resume()
136 // (*) If x.await_suspend return type is bool, it allows to veto a suspend:
137 // if (x.await_suspend(...))
138 // llvm_coro_suspend();
140 // (**) llvm_coro_suspend() encodes three possible continuations as
141 // a switch instruction:
143 // %where-to = call i8 @llvm.coro.suspend(...)
144 // switch i8 %where-to, label %coro.ret [ ; jump to epilogue to suspend
145 // i8 0, label %yield.ready ; go here when resumed
146 // i8 1, label %yield.cleanup ; go here when destroyed
149 // See llvm's docs/Coroutines.rst for more details.
152 struct LValueOrRValue {
157 static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Coro,
158 CoroutineSuspendExpr const &S,
159 AwaitKind Kind, AggValueSlot aggSlot,
160 bool ignoreResult, bool forLValue) {
161 auto *E = S.getCommonExpr();
164 CodeGenFunction::OpaqueValueMappingData::bind(CGF, S.getOpaqueValue(), E);
165 auto UnbindOnExit = llvm::make_scope_exit([&] { Binder.unbind(CGF); });
167 auto Prefix = buildSuspendPrefixStr(Coro, Kind);
168 BasicBlock *ReadyBlock = CGF.createBasicBlock(Prefix + Twine(".ready"));
169 BasicBlock *SuspendBlock = CGF.createBasicBlock(Prefix + Twine(".suspend"));
170 BasicBlock *CleanupBlock = CGF.createBasicBlock(Prefix + Twine(".cleanup"));
172 // If expression is ready, no need to suspend.
173 CGF.EmitBranchOnBoolExpr(S.getReadyExpr(), ReadyBlock, SuspendBlock, 0);
175 // Otherwise, emit suspend logic.
176 CGF.EmitBlock(SuspendBlock);
178 auto &Builder = CGF.Builder;
179 llvm::Function *CoroSave = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_save);
180 auto *NullPtr = llvm::ConstantPointerNull::get(CGF.CGM.Int8PtrTy);
181 auto *SaveCall = Builder.CreateCall(CoroSave, {NullPtr});
183 auto *SuspendRet = CGF.EmitScalarExpr(S.getSuspendExpr());
184 if (SuspendRet != nullptr && SuspendRet->getType()->isIntegerTy(1)) {
185 // Veto suspension if requested by bool returning await_suspend.
186 BasicBlock *RealSuspendBlock =
187 CGF.createBasicBlock(Prefix + Twine(".suspend.bool"));
188 CGF.Builder.CreateCondBr(SuspendRet, RealSuspendBlock, ReadyBlock);
189 SuspendBlock = RealSuspendBlock;
190 CGF.EmitBlock(RealSuspendBlock);
193 // Emit the suspend point.
194 const bool IsFinalSuspend = (Kind == AwaitKind::Final);
195 llvm::Function *CoroSuspend =
196 CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_suspend);
197 auto *SuspendResult = Builder.CreateCall(
198 CoroSuspend, {SaveCall, Builder.getInt1(IsFinalSuspend)});
200 // Create a switch capturing three possible continuations.
201 auto *Switch = Builder.CreateSwitch(SuspendResult, Coro.SuspendBB, 2);
202 Switch->addCase(Builder.getInt8(0), ReadyBlock);
203 Switch->addCase(Builder.getInt8(1), CleanupBlock);
205 // Emit cleanup for this suspend point.
206 CGF.EmitBlock(CleanupBlock);
207 CGF.EmitBranchThroughCleanup(Coro.CleanupJD);
209 // Emit await_resume expression.
210 CGF.EmitBlock(ReadyBlock);
213 Res.LV = CGF.EmitLValue(S.getResumeExpr());
215 Res.RV = CGF.EmitAnyExpr(S.getResumeExpr(), aggSlot, ignoreResult);
219 RValue CodeGenFunction::EmitCoawaitExpr(const CoawaitExpr &E,
220 AggValueSlot aggSlot,
222 return emitSuspendExpression(*this, *CurCoro.Data, E,
223 CurCoro.Data->CurrentAwaitKind, aggSlot,
224 ignoreResult, /*forLValue*/false).RV;
226 RValue CodeGenFunction::EmitCoyieldExpr(const CoyieldExpr &E,
227 AggValueSlot aggSlot,
229 return emitSuspendExpression(*this, *CurCoro.Data, E, AwaitKind::Yield,
230 aggSlot, ignoreResult, /*forLValue*/false).RV;
233 void CodeGenFunction::EmitCoreturnStmt(CoreturnStmt const &S) {
234 ++CurCoro.Data->CoreturnCount;
235 const Expr *RV = S.getOperand();
236 if (RV && RV->getType()->isVoidType()) {
237 // Make sure to evaluate the expression of a co_return with a void
238 // expression for side effects.
239 RunCleanupsScope cleanupScope(*this);
242 EmitStmt(S.getPromiseCall());
243 EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
248 static QualType getCoroutineSuspendExprReturnType(const ASTContext &Ctx,
249 const CoroutineSuspendExpr *E) {
250 const auto *RE = E->getResumeExpr();
251 // Is it possible for RE to be a CXXBindTemporaryExpr wrapping
253 assert(isa<CallExpr>(RE) && "unexpected suspend expression type");
254 return cast<CallExpr>(RE)->getCallReturnType(Ctx);
259 CodeGenFunction::EmitCoawaitLValue(const CoawaitExpr *E) {
260 assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
261 "Can't have a scalar return unless the return type is a "
263 return emitSuspendExpression(*this, *CurCoro.Data, *E,
264 CurCoro.Data->CurrentAwaitKind, AggValueSlot::ignored(),
265 /*ignoreResult*/false, /*forLValue*/true).LV;
269 CodeGenFunction::EmitCoyieldLValue(const CoyieldExpr *E) {
270 assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&
271 "Can't have a scalar return unless the return type is a "
273 return emitSuspendExpression(*this, *CurCoro.Data, *E,
274 AwaitKind::Yield, AggValueSlot::ignored(),
275 /*ignoreResult*/false, /*forLValue*/true).LV;
278 // Hunts for the parameter reference in the parameter copy/move declaration.
280 struct GetParamRef : public StmtVisitor<GetParamRef> {
282 DeclRefExpr *Expr = nullptr;
284 void VisitDeclRefExpr(DeclRefExpr *E) {
285 assert(Expr == nullptr && "multilple declref in param move");
288 void VisitStmt(Stmt *S) {
289 for (auto *C : S->children()) {
297 // This class replaces references to parameters to their copies by changing
298 // the addresses in CGF.LocalDeclMap and restoring back the original values in
302 struct ParamReferenceReplacerRAII {
303 CodeGenFunction::DeclMapTy SavedLocals;
304 CodeGenFunction::DeclMapTy& LocalDeclMap;
306 ParamReferenceReplacerRAII(CodeGenFunction::DeclMapTy &LocalDeclMap)
307 : LocalDeclMap(LocalDeclMap) {}
309 void addCopy(DeclStmt const *PM) {
310 // Figure out what param it refers to.
312 assert(PM->isSingleDecl());
313 VarDecl const*VD = static_cast<VarDecl const*>(PM->getSingleDecl());
314 Expr const *InitExpr = VD->getInit();
316 Visitor.Visit(const_cast<Expr*>(InitExpr));
317 assert(Visitor.Expr);
318 auto *DREOrig = cast<DeclRefExpr>(Visitor.Expr);
319 auto *PD = DREOrig->getDecl();
321 auto it = LocalDeclMap.find(PD);
322 assert(it != LocalDeclMap.end() && "parameter is not found");
323 SavedLocals.insert({ PD, it->second });
325 auto copyIt = LocalDeclMap.find(VD);
326 assert(copyIt != LocalDeclMap.end() && "parameter copy is not found");
327 it->second = copyIt->getSecond();
330 ~ParamReferenceReplacerRAII() {
331 for (auto&& SavedLocal : SavedLocals) {
332 LocalDeclMap.insert({SavedLocal.first, SavedLocal.second});
338 // For WinEH exception representation backend needs to know what funclet coro.end
339 // belongs to. That information is passed in a funclet bundle.
340 static SmallVector<llvm::OperandBundleDef, 1>
341 getBundlesForCoroEnd(CodeGenFunction &CGF) {
342 SmallVector<llvm::OperandBundleDef, 1> BundleList;
344 if (llvm::Instruction *EHPad = CGF.CurrentFuncletPad)
345 BundleList.emplace_back("funclet", EHPad);
351 // We will insert coro.end to cut any of the destructors for objects that
352 // do not need to be destroyed once the coroutine is resumed.
353 // See llvm/docs/Coroutines.rst for more details about coro.end.
354 struct CallCoroEnd final : public EHScopeStack::Cleanup {
355 void Emit(CodeGenFunction &CGF, Flags flags) override {
357 auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
358 llvm::Function *CoroEndFn = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
359 // See if we have a funclet bundle to associate coro.end with. (WinEH)
360 auto Bundles = getBundlesForCoroEnd(CGF);
361 auto *CoroEnd = CGF.Builder.CreateCall(
362 CoroEndFn, {NullPtr, CGF.Builder.getTrue()}, Bundles);
363 if (Bundles.empty()) {
364 // Otherwise, (landingpad model), create a conditional branch that leads
365 // either to a cleanup block or a block with EH resume instruction.
366 auto *ResumeBB = CGF.getEHResumeBlock(/*cleanup=*/true);
367 auto *CleanupContBB = CGF.createBasicBlock("cleanup.cont");
368 CGF.Builder.CreateCondBr(CoroEnd, ResumeBB, CleanupContBB);
369 CGF.EmitBlock(CleanupContBB);
376 // Make sure to call coro.delete on scope exit.
377 struct CallCoroDelete final : public EHScopeStack::Cleanup {
380 // Emit "if (coro.free(CoroId, CoroBegin)) Deallocate;"
382 // Note: That deallocation will be emitted twice: once for a normal exit and
383 // once for exceptional exit. This usage is safe because Deallocate does not
384 // contain any declarations. The SubStmtBuilder::makeNewAndDeleteExpr()
385 // builds a single call to a deallocation function which is safe to emit
387 void Emit(CodeGenFunction &CGF, Flags) override {
388 // Remember the current point, as we are going to emit deallocation code
389 // first to get to coro.free instruction that is an argument to a delete
391 BasicBlock *SaveInsertBlock = CGF.Builder.GetInsertBlock();
393 auto *FreeBB = CGF.createBasicBlock("coro.free");
394 CGF.EmitBlock(FreeBB);
395 CGF.EmitStmt(Deallocate);
397 auto *AfterFreeBB = CGF.createBasicBlock("after.coro.free");
398 CGF.EmitBlock(AfterFreeBB);
400 // We should have captured coro.free from the emission of deallocate.
401 auto *CoroFree = CGF.CurCoro.Data->LastCoroFree;
403 CGF.CGM.Error(Deallocate->getLocStart(),
404 "Deallocation expressoin does not refer to coro.free");
408 // Get back to the block we were originally and move coro.free there.
409 auto *InsertPt = SaveInsertBlock->getTerminator();
410 CoroFree->moveBefore(InsertPt);
411 CGF.Builder.SetInsertPoint(InsertPt);
413 // Add if (auto *mem = coro.free) Deallocate;
414 auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
415 auto *Cond = CGF.Builder.CreateICmpNE(CoroFree, NullPtr);
416 CGF.Builder.CreateCondBr(Cond, FreeBB, AfterFreeBB);
418 // No longer need old terminator.
419 InsertPt->eraseFromParent();
420 CGF.Builder.SetInsertPoint(AfterFreeBB);
422 explicit CallCoroDelete(Stmt *DeallocStmt) : Deallocate(DeallocStmt) {}
427 struct GetReturnObjectManager {
428 CodeGenFunction &CGF;
429 CGBuilderTy &Builder;
430 const CoroutineBodyStmt &S;
432 Address GroActiveFlag;
433 CodeGenFunction::AutoVarEmission GroEmission;
435 GetReturnObjectManager(CodeGenFunction &CGF, const CoroutineBodyStmt &S)
436 : CGF(CGF), Builder(CGF.Builder), S(S), GroActiveFlag(Address::invalid()),
437 GroEmission(CodeGenFunction::AutoVarEmission::invalid()) {}
439 // The gro variable has to outlive coroutine frame and coroutine promise, but,
440 // it can only be initialized after coroutine promise was created, thus, we
441 // split its emission in two parts. EmitGroAlloca emits an alloca and sets up
442 // cleanups. Later when coroutine promise is available we initialize the gro
443 // and sets the flag that the cleanup is now active.
445 void EmitGroAlloca() {
446 auto *GroDeclStmt = dyn_cast<DeclStmt>(S.getResultDecl());
448 // If get_return_object returns void, no need to do an alloca.
452 auto *GroVarDecl = cast<VarDecl>(GroDeclStmt->getSingleDecl());
454 // Set GRO flag that it is not initialized yet
456 CGF.CreateTempAlloca(Builder.getInt1Ty(), CharUnits::One(), "gro.active");
457 Builder.CreateStore(Builder.getFalse(), GroActiveFlag);
459 GroEmission = CGF.EmitAutoVarAlloca(*GroVarDecl);
461 // Remember the top of EHStack before emitting the cleanup.
462 auto old_top = CGF.EHStack.stable_begin();
463 CGF.EmitAutoVarCleanups(GroEmission);
464 auto top = CGF.EHStack.stable_begin();
466 // Make the cleanup conditional on gro.active
467 for (auto b = CGF.EHStack.find(top), e = CGF.EHStack.find(old_top);
469 if (auto *Cleanup = dyn_cast<EHCleanupScope>(&*b)) {
470 assert(!Cleanup->hasActiveFlag() && "cleanup already has active flag?");
471 Cleanup->setActiveFlag(GroActiveFlag);
472 Cleanup->setTestFlagInEHCleanup();
473 Cleanup->setTestFlagInNormalCleanup();
479 if (!GroActiveFlag.isValid()) {
480 // No Gro variable was allocated. Simply emit the call to
481 // get_return_object.
482 CGF.EmitStmt(S.getResultDecl());
486 CGF.EmitAutoVarInit(GroEmission);
487 Builder.CreateStore(Builder.getTrue(), GroActiveFlag);
492 static void emitBodyAndFallthrough(CodeGenFunction &CGF,
493 const CoroutineBodyStmt &S, Stmt *Body) {
495 const bool CanFallthrough = CGF.Builder.GetInsertBlock();
497 if (Stmt *OnFallthrough = S.getFallthroughHandler())
498 CGF.EmitStmt(OnFallthrough);
501 void CodeGenFunction::EmitCoroutineBody(const CoroutineBodyStmt &S) {
502 auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
503 auto &TI = CGM.getContext().getTargetInfo();
504 unsigned NewAlign = TI.getNewAlign() / TI.getCharWidth();
506 auto *EntryBB = Builder.GetInsertBlock();
507 auto *AllocBB = createBasicBlock("coro.alloc");
508 auto *InitBB = createBasicBlock("coro.init");
509 auto *FinalBB = createBasicBlock("coro.final");
510 auto *RetBB = createBasicBlock("coro.ret");
512 auto *CoroId = Builder.CreateCall(
513 CGM.getIntrinsic(llvm::Intrinsic::coro_id),
514 {Builder.getInt32(NewAlign), NullPtr, NullPtr, NullPtr});
515 createCoroData(*this, CurCoro, CoroId);
516 CurCoro.Data->SuspendBB = RetBB;
518 // Backend is allowed to elide memory allocations, to help it, emit
519 // auto mem = coro.alloc() ? 0 : ... allocation code ...;
520 auto *CoroAlloc = Builder.CreateCall(
521 CGM.getIntrinsic(llvm::Intrinsic::coro_alloc), {CoroId});
523 Builder.CreateCondBr(CoroAlloc, AllocBB, InitBB);
526 auto *AllocateCall = EmitScalarExpr(S.getAllocate());
527 auto *AllocOrInvokeContBB = Builder.GetInsertBlock();
529 // Handle allocation failure if 'ReturnStmtOnAllocFailure' was provided.
530 if (auto *RetOnAllocFailure = S.getReturnStmtOnAllocFailure()) {
531 auto *RetOnFailureBB = createBasicBlock("coro.ret.on.failure");
533 // See if allocation was successful.
534 auto *NullPtr = llvm::ConstantPointerNull::get(Int8PtrTy);
535 auto *Cond = Builder.CreateICmpNE(AllocateCall, NullPtr);
536 Builder.CreateCondBr(Cond, InitBB, RetOnFailureBB);
538 // If not, return OnAllocFailure object.
539 EmitBlock(RetOnFailureBB);
540 EmitStmt(RetOnAllocFailure);
543 Builder.CreateBr(InitBB);
548 // Pass the result of the allocation to coro.begin.
549 auto *Phi = Builder.CreatePHI(VoidPtrTy, 2);
550 Phi->addIncoming(NullPtr, EntryBB);
551 Phi->addIncoming(AllocateCall, AllocOrInvokeContBB);
552 auto *CoroBegin = Builder.CreateCall(
553 CGM.getIntrinsic(llvm::Intrinsic::coro_begin), {CoroId, Phi});
554 CurCoro.Data->CoroBegin = CoroBegin;
556 GetReturnObjectManager GroManager(*this, S);
557 GroManager.EmitGroAlloca();
559 CurCoro.Data->CleanupJD = getJumpDestInCurrentScope(RetBB);
561 ParamReferenceReplacerRAII ParamReplacer(LocalDeclMap);
562 CodeGenFunction::RunCleanupsScope ResumeScope(*this);
563 EHStack.pushCleanup<CallCoroDelete>(NormalAndEHCleanup, S.getDeallocate());
565 // Create parameter copies. We do it before creating a promise, since an
566 // evolution of coroutine TS may allow promise constructor to observe
568 for (auto *PM : S.getParamMoves()) {
570 ParamReplacer.addCopy(cast<DeclStmt>(PM));
571 // TODO: if(CoroParam(...)) need to surround ctor and dtor
572 // for the copy, so that llvm can elide it if the copy is
576 EmitStmt(S.getPromiseDeclStmt());
578 Address PromiseAddr = GetAddrOfLocalVar(S.getPromiseDecl());
579 auto *PromiseAddrVoidPtr =
580 new llvm::BitCastInst(PromiseAddr.getPointer(), VoidPtrTy, "", CoroId);
581 // Update CoroId to refer to the promise. We could not do it earlier because
582 // promise local variable was not emitted yet.
583 CoroId->setArgOperand(1, PromiseAddrVoidPtr);
585 // Now we have the promise, initialize the GRO
586 GroManager.EmitGroInit();
588 EHStack.pushCleanup<CallCoroEnd>(EHCleanup);
590 CurCoro.Data->CurrentAwaitKind = AwaitKind::Init;
591 EmitStmt(S.getInitSuspendStmt());
592 CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
594 CurCoro.Data->CurrentAwaitKind = AwaitKind::Normal;
596 if (auto *OnException = S.getExceptionHandler()) {
597 auto Loc = S.getLocStart();
598 CXXCatchStmt Catch(Loc, /*exDecl=*/nullptr, OnException);
599 auto *TryStmt = CXXTryStmt::Create(getContext(), Loc, S.getBody(), &Catch);
601 EnterCXXTryStmt(*TryStmt);
602 emitBodyAndFallthrough(*this, S, TryStmt->getTryBlock());
603 ExitCXXTryStmt(*TryStmt);
606 emitBodyAndFallthrough(*this, S, S.getBody());
609 // See if we need to generate final suspend.
610 const bool CanFallthrough = Builder.GetInsertBlock();
611 const bool HasCoreturns = CurCoro.Data->CoreturnCount > 0;
612 if (CanFallthrough || HasCoreturns) {
614 CurCoro.Data->CurrentAwaitKind = AwaitKind::Final;
615 EmitStmt(S.getFinalSuspendStmt());
617 // We don't need FinalBB. Emit it to make sure the block is deleted.
618 EmitBlock(FinalBB, /*IsFinished=*/true);
623 // Emit coro.end before getReturnStmt (and parameter destructors), since
624 // resume and destroy parts of the coroutine should not include them.
625 llvm::Function *CoroEnd = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
626 Builder.CreateCall(CoroEnd, {NullPtr, Builder.getFalse()});
628 if (Stmt *Ret = S.getReturnStmt())
632 // Emit coroutine intrinsic and patch up arguments of the token type.
633 RValue CodeGenFunction::EmitCoroutineIntrinsic(const CallExpr *E,
635 SmallVector<llvm::Value *, 8> Args;
639 // The coro.frame builtin is replaced with an SSA value of the coro.begin
641 case llvm::Intrinsic::coro_frame: {
642 if (CurCoro.Data && CurCoro.Data->CoroBegin) {
643 return RValue::get(CurCoro.Data->CoroBegin);
645 CGM.Error(E->getLocStart(), "this builtin expect that __builtin_coro_begin "
646 "has been used earlier in this function");
647 auto NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
648 return RValue::get(NullPtr);
650 // The following three intrinsics take a token parameter referring to a token
651 // returned by earlier call to @llvm.coro.id. Since we cannot represent it in
652 // builtins, we patch it up here.
653 case llvm::Intrinsic::coro_alloc:
654 case llvm::Intrinsic::coro_begin:
655 case llvm::Intrinsic::coro_free: {
656 if (CurCoro.Data && CurCoro.Data->CoroId) {
657 Args.push_back(CurCoro.Data->CoroId);
660 CGM.Error(E->getLocStart(), "this builtin expect that __builtin_coro_id has"
661 " been used earlier in this function");
662 // Fallthrough to the next case to add TokenNone as the first argument.
665 // @llvm.coro.suspend takes a token parameter. Add token 'none' as the first
667 case llvm::Intrinsic::coro_suspend:
668 Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
671 for (auto &Arg : E->arguments())
672 Args.push_back(EmitScalarExpr(Arg));
674 llvm::Value *F = CGM.getIntrinsic(IID);
675 llvm::CallInst *Call = Builder.CreateCall(F, Args);
677 // Note: The following code is to enable to emit coro.id and coro.begin by
678 // hand to experiment with coroutines in C.
679 // If we see @llvm.coro.id remember it in the CoroData. We will update
680 // coro.alloc, coro.begin and coro.free intrinsics to refer to it.
681 if (IID == llvm::Intrinsic::coro_id) {
682 createCoroData(*this, CurCoro, Call, E);
684 else if (IID == llvm::Intrinsic::coro_begin) {
686 CurCoro.Data->CoroBegin = Call;
688 else if (IID == llvm::Intrinsic::coro_free) {
689 // Remember the last coro_free as we need it to build the conditional
690 // deletion of the coroutine frame.
692 CurCoro.Data->LastCoroFree = Call;
694 return RValue::get(Call);