Bug Summary

File:tools/clang/lib/CodeGen/CGCoroutine.cpp
Warning:line 191, column 5
Value stored to 'SuspendBlock' is never read

Annotated Source Code

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
20using namespace clang;
21using namespace CodeGen;
22
23using llvm::Value;
24using llvm::BasicBlock;
25
26namespace {
27enum class AwaitKind { Init, Normal, Yield, Final };
28static constexpr llvm::StringLiteral AwaitKindStr[] = {"init", "await", "yield",
29 "final"};
30}
31
32struct 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;
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 // 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
49 // branch.
50 CodeGenFunction::JumpDest CleanupJD;
51
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;
55
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
59 // builtin.
60 llvm::CallInst *CoroId = nullptr;
61
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;
66
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;
70
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
73 // EmitCoroutineBody.
74 CallExpr const *CoroIdExpr = nullptr;
75};
76
77// Defining these here allows to keep CGCoroData private to this file.
78clang::CodeGen::CodeGenFunction::CGCoroInfo::CGCoroInfo() {}
79CodeGenFunction::CGCoroInfo::~CGCoroInfo() {}
80
81static void createCoroData(CodeGenFunction &CGF,
82 CodeGenFunction::CGCoroInfo &CurCoro,
83 llvm::CallInst *CoroId,
84 CallExpr const *CoroIdExpr = nullptr) {
85 if (CurCoro.Data) {
86 if (CurCoro.Data->CoroIdExpr)
87 CGF.CGM.Error(CoroIdExpr->getLocStart(),
88 "only one __builtin_coro_id can be used in a function");
89 else if (CoroIdExpr)
90 CGF.CGM.Error(CoroIdExpr->getLocStart(),
91 "__builtin_coro_id shall not be used in a C++ coroutine");
92 else
93 llvm_unreachable("EmitCoroutineBodyStatement called twice?")::llvm::llvm_unreachable_internal("EmitCoroutineBodyStatement called twice?"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 93);
94
95 return;
96 }
97
98 CurCoro.Data = std::unique_ptr<CGCoroData>(new CGCoroData);
99 CurCoro.Data->CoroId = CoroId;
100 CurCoro.Data->CoroIdExpr = CoroIdExpr;
101}
102
103// Synthesize a pretty name for a suspend point.
104static SmallString<32> buildSuspendPrefixStr(CGCoroData &Coro, AwaitKind Kind) {
105 unsigned No = 0;
106 switch (Kind) {
107 case AwaitKind::Init:
108 case AwaitKind::Final:
109 break;
110 case AwaitKind::Normal:
111 No = ++Coro.AwaitNum;
112 break;
113 case AwaitKind::Yield:
114 No = ++Coro.YieldNum;
115 break;
116 }
117 SmallString<32> Prefix(AwaitKindStr[static_cast<unsigned>(Kind)]);
118 if (No > 1) {
119 Twine(No).toVector(Prefix);
120 }
121 return Prefix;
122}
123
124// Emit suspend expression which roughly looks like:
125//
126// auto && x = CommonExpr();
127// if (!x.await_ready()) {
128// llvm_coro_save();
129// x.await_suspend(...); (*)
130// llvm_coro_suspend(); (**)
131// }
132// x.await_resume();
133//
134// where the result of the entire expression is the result of x.await_resume()
135//
136// (*) If x.await_suspend return type is bool, it allows to veto a suspend:
137// if (x.await_suspend(...))
138// llvm_coro_suspend();
139//
140// (**) llvm_coro_suspend() encodes three possible continuations as
141// a switch instruction:
142//
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
147// ]
148//
149// See llvm's docs/Coroutines.rst for more details.
150//
151namespace {
152 struct LValueOrRValue {
153 LValue LV;
154 RValue RV;
155 };
156}
157static 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();
162
163 auto Binder =
164 CodeGenFunction::OpaqueValueMappingData::bind(CGF, S.getOpaqueValue(), E);
165 auto UnbindOnExit = llvm::make_scope_exit([&] { Binder.unbind(CGF); });
166
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"));
171
172 // If expression is ready, no need to suspend.
173 CGF.EmitBranchOnBoolExpr(S.getReadyExpr(), ReadyBlock, SuspendBlock, 0);
174
175 // Otherwise, emit suspend logic.
176 CGF.EmitBlock(SuspendBlock);
177
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});
182
183 auto *SuspendRet = CGF.EmitScalarExpr(S.getSuspendExpr());
184 if (SuspendRet != nullptr) {
185 // Veto suspension if requested by bool returning await_suspend.
186 assert(SuspendRet->getType()->isIntegerTy(1) &&((SuspendRet->getType()->isIntegerTy(1) && "Sema should have already checked that it is void or bool"
) ? static_cast<void> (0) : __assert_fail ("SuspendRet->getType()->isIntegerTy(1) && \"Sema should have already checked that it is void or bool\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 187, __PRETTY_FUNCTION__))
187 "Sema should have already checked that it is void or bool")((SuspendRet->getType()->isIntegerTy(1) && "Sema should have already checked that it is void or bool"
) ? static_cast<void> (0) : __assert_fail ("SuspendRet->getType()->isIntegerTy(1) && \"Sema should have already checked that it is void or bool\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 187, __PRETTY_FUNCTION__));
188 BasicBlock *RealSuspendBlock =
189 CGF.createBasicBlock(Prefix + Twine(".suspend.bool"));
190 CGF.Builder.CreateCondBr(SuspendRet, RealSuspendBlock, ReadyBlock);
191 SuspendBlock = RealSuspendBlock;
Value stored to 'SuspendBlock' is never read
192 CGF.EmitBlock(RealSuspendBlock);
193 }
194
195 // Emit the suspend point.
196 const bool IsFinalSuspend = (Kind == AwaitKind::Final);
197 llvm::Function *CoroSuspend =
198 CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_suspend);
199 auto *SuspendResult = Builder.CreateCall(
200 CoroSuspend, {SaveCall, Builder.getInt1(IsFinalSuspend)});
201
202 // Create a switch capturing three possible continuations.
203 auto *Switch = Builder.CreateSwitch(SuspendResult, Coro.SuspendBB, 2);
204 Switch->addCase(Builder.getInt8(0), ReadyBlock);
205 Switch->addCase(Builder.getInt8(1), CleanupBlock);
206
207 // Emit cleanup for this suspend point.
208 CGF.EmitBlock(CleanupBlock);
209 CGF.EmitBranchThroughCleanup(Coro.CleanupJD);
210
211 // Emit await_resume expression.
212 CGF.EmitBlock(ReadyBlock);
213 LValueOrRValue Res;
214 if (forLValue)
215 Res.LV = CGF.EmitLValue(S.getResumeExpr());
216 else
217 Res.RV = CGF.EmitAnyExpr(S.getResumeExpr(), aggSlot, ignoreResult);
218 return Res;
219}
220
221RValue CodeGenFunction::EmitCoawaitExpr(const CoawaitExpr &E,
222 AggValueSlot aggSlot,
223 bool ignoreResult) {
224 return emitSuspendExpression(*this, *CurCoro.Data, E,
225 CurCoro.Data->CurrentAwaitKind, aggSlot,
226 ignoreResult, /*forLValue*/false).RV;
227}
228RValue CodeGenFunction::EmitCoyieldExpr(const CoyieldExpr &E,
229 AggValueSlot aggSlot,
230 bool ignoreResult) {
231 return emitSuspendExpression(*this, *CurCoro.Data, E, AwaitKind::Yield,
232 aggSlot, ignoreResult, /*forLValue*/false).RV;
233}
234
235void CodeGenFunction::EmitCoreturnStmt(CoreturnStmt const &S) {
236 ++CurCoro.Data->CoreturnCount;
237 EmitStmt(S.getPromiseCall());
238 EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
239}
240
241
242#ifndef NDEBUG
243static QualType getCoroutineSuspendExprReturnType(const ASTContext &Ctx,
244 const CoroutineSuspendExpr *E) {
245 const auto *RE = E->getResumeExpr();
246 // Is it possible for RE to be a CXXBindTemporaryExpr wrapping
247 // a MemberCallExpr?
248 assert(isa<CallExpr>(RE) && "unexpected suspend expression type")((isa<CallExpr>(RE) && "unexpected suspend expression type"
) ? static_cast<void> (0) : __assert_fail ("isa<CallExpr>(RE) && \"unexpected suspend expression type\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 248, __PRETTY_FUNCTION__));
249 return cast<CallExpr>(RE)->getCallReturnType(Ctx);
250}
251#endif
252
253LValue
254CodeGenFunction::EmitCoawaitLValue(const CoawaitExpr *E) {
255 assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&((getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType
() && "Can't have a scalar return unless the return type is a "
"reference type!") ? static_cast<void> (0) : __assert_fail
("getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() && \"Can't have a scalar return unless the return type is a \" \"reference type!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 257, __PRETTY_FUNCTION__))
256 "Can't have a scalar return unless the return type is a "((getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType
() && "Can't have a scalar return unless the return type is a "
"reference type!") ? static_cast<void> (0) : __assert_fail
("getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() && \"Can't have a scalar return unless the return type is a \" \"reference type!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 257, __PRETTY_FUNCTION__))
257 "reference type!")((getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType
() && "Can't have a scalar return unless the return type is a "
"reference type!") ? static_cast<void> (0) : __assert_fail
("getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() && \"Can't have a scalar return unless the return type is a \" \"reference type!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 257, __PRETTY_FUNCTION__));
258 return emitSuspendExpression(*this, *CurCoro.Data, *E,
259 CurCoro.Data->CurrentAwaitKind, AggValueSlot::ignored(),
260 /*ignoreResult*/false, /*forLValue*/true).LV;
261}
262
263LValue
264CodeGenFunction::EmitCoyieldLValue(const CoyieldExpr *E) {
265 assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&((getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType
() && "Can't have a scalar return unless the return type is a "
"reference type!") ? static_cast<void> (0) : __assert_fail
("getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() && \"Can't have a scalar return unless the return type is a \" \"reference type!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 267, __PRETTY_FUNCTION__))
266 "Can't have a scalar return unless the return type is a "((getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType
() && "Can't have a scalar return unless the return type is a "
"reference type!") ? static_cast<void> (0) : __assert_fail
("getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() && \"Can't have a scalar return unless the return type is a \" \"reference type!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 267, __PRETTY_FUNCTION__))
267 "reference type!")((getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType
() && "Can't have a scalar return unless the return type is a "
"reference type!") ? static_cast<void> (0) : __assert_fail
("getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() && \"Can't have a scalar return unless the return type is a \" \"reference type!\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 267, __PRETTY_FUNCTION__));
268 return emitSuspendExpression(*this, *CurCoro.Data, *E,
269 AwaitKind::Yield, AggValueSlot::ignored(),
270 /*ignoreResult*/false, /*forLValue*/true).LV;
271}
272
273// Hunts for the parameter reference in the parameter copy/move declaration.
274namespace {
275struct GetParamRef : public StmtVisitor<GetParamRef> {
276public:
277 DeclRefExpr *Expr = nullptr;
278 GetParamRef() {}
279 void VisitDeclRefExpr(DeclRefExpr *E) {
280 assert(Expr == nullptr && "multilple declref in param move")((Expr == nullptr && "multilple declref in param move"
) ? static_cast<void> (0) : __assert_fail ("Expr == nullptr && \"multilple declref in param move\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 280, __PRETTY_FUNCTION__));
281 Expr = E;
282 }
283 void VisitStmt(Stmt *S) {
284 for (auto *C : S->children()) {
285 if (C)
286 Visit(C);
287 }
288 }
289};
290}
291
292// This class replaces references to parameters to their copies by changing
293// the addresses in CGF.LocalDeclMap and restoring back the original values in
294// its destructor.
295
296namespace {
297 struct ParamReferenceReplacerRAII {
298 CodeGenFunction::DeclMapTy SavedLocals;
299 CodeGenFunction::DeclMapTy& LocalDeclMap;
300
301 ParamReferenceReplacerRAII(CodeGenFunction::DeclMapTy &LocalDeclMap)
302 : LocalDeclMap(LocalDeclMap) {}
303
304 void addCopy(DeclStmt const *PM) {
305 // Figure out what param it refers to.
306
307 assert(PM->isSingleDecl())((PM->isSingleDecl()) ? static_cast<void> (0) : __assert_fail
("PM->isSingleDecl()", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 307, __PRETTY_FUNCTION__));
308 VarDecl const*VD = static_cast<VarDecl const*>(PM->getSingleDecl());
309 Expr const *InitExpr = VD->getInit();
310 GetParamRef Visitor;
311 Visitor.Visit(const_cast<Expr*>(InitExpr));
312 assert(Visitor.Expr)((Visitor.Expr) ? static_cast<void> (0) : __assert_fail
("Visitor.Expr", "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 312, __PRETTY_FUNCTION__));
313 auto *DREOrig = cast<DeclRefExpr>(Visitor.Expr);
314 auto *PD = DREOrig->getDecl();
315
316 auto it = LocalDeclMap.find(PD);
317 assert(it != LocalDeclMap.end() && "parameter is not found")((it != LocalDeclMap.end() && "parameter is not found"
) ? static_cast<void> (0) : __assert_fail ("it != LocalDeclMap.end() && \"parameter is not found\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 317, __PRETTY_FUNCTION__));
318 SavedLocals.insert({ PD, it->second });
319
320 auto copyIt = LocalDeclMap.find(VD);
321 assert(copyIt != LocalDeclMap.end() && "parameter copy is not found")((copyIt != LocalDeclMap.end() && "parameter copy is not found"
) ? static_cast<void> (0) : __assert_fail ("copyIt != LocalDeclMap.end() && \"parameter copy is not found\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 321, __PRETTY_FUNCTION__));
322 it->second = copyIt->getSecond();
323 }
324
325 ~ParamReferenceReplacerRAII() {
326 for (auto&& SavedLocal : SavedLocals) {
327 LocalDeclMap.insert({SavedLocal.first, SavedLocal.second});
328 }
329 }
330 };
331}
332
333// For WinEH exception representation backend needs to know what funclet coro.end
334// belongs to. That information is passed in a funclet bundle.
335static SmallVector<llvm::OperandBundleDef, 1>
336getBundlesForCoroEnd(CodeGenFunction &CGF) {
337 SmallVector<llvm::OperandBundleDef, 1> BundleList;
338
339 if (llvm::Instruction *EHPad = CGF.CurrentFuncletPad)
340 BundleList.emplace_back("funclet", EHPad);
341
342 return BundleList;
343}
344
345namespace {
346// We will insert coro.end to cut any of the destructors for objects that
347// do not need to be destroyed once the coroutine is resumed.
348// See llvm/docs/Coroutines.rst for more details about coro.end.
349struct CallCoroEnd final : public EHScopeStack::Cleanup {
350 void Emit(CodeGenFunction &CGF, Flags flags) override {
351 auto &CGM = CGF.CGM;
352 auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
353 llvm::Function *CoroEndFn = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
354 // See if we have a funclet bundle to associate coro.end with. (WinEH)
355 auto Bundles = getBundlesForCoroEnd(CGF);
356 auto *CoroEnd = CGF.Builder.CreateCall(
357 CoroEndFn, {NullPtr, CGF.Builder.getTrue()}, Bundles);
358 if (Bundles.empty()) {
359 // Otherwise, (landingpad model), create a conditional branch that leads
360 // either to a cleanup block or a block with EH resume instruction.
361 auto *ResumeBB = CGF.getEHResumeBlock(/*cleanup=*/true);
362 auto *CleanupContBB = CGF.createBasicBlock("cleanup.cont");
363 CGF.Builder.CreateCondBr(CoroEnd, ResumeBB, CleanupContBB);
364 CGF.EmitBlock(CleanupContBB);
365 }
366 }
367};
368}
369
370namespace {
371// Make sure to call coro.delete on scope exit.
372struct CallCoroDelete final : public EHScopeStack::Cleanup {
373 Stmt *Deallocate;
374
375 // Emit "if (coro.free(CoroId, CoroBegin)) Deallocate;"
376
377 // Note: That deallocation will be emitted twice: once for a normal exit and
378 // once for exceptional exit. This usage is safe because Deallocate does not
379 // contain any declarations. The SubStmtBuilder::makeNewAndDeleteExpr()
380 // builds a single call to a deallocation function which is safe to emit
381 // multiple times.
382 void Emit(CodeGenFunction &CGF, Flags) override {
383 // Remember the current point, as we are going to emit deallocation code
384 // first to get to coro.free instruction that is an argument to a delete
385 // call.
386 BasicBlock *SaveInsertBlock = CGF.Builder.GetInsertBlock();
387
388 auto *FreeBB = CGF.createBasicBlock("coro.free");
389 CGF.EmitBlock(FreeBB);
390 CGF.EmitStmt(Deallocate);
391
392 auto *AfterFreeBB = CGF.createBasicBlock("after.coro.free");
393 CGF.EmitBlock(AfterFreeBB);
394
395 // We should have captured coro.free from the emission of deallocate.
396 auto *CoroFree = CGF.CurCoro.Data->LastCoroFree;
397 if (!CoroFree) {
398 CGF.CGM.Error(Deallocate->getLocStart(),
399 "Deallocation expressoin does not refer to coro.free");
400 return;
401 }
402
403 // Get back to the block we were originally and move coro.free there.
404 auto *InsertPt = SaveInsertBlock->getTerminator();
405 CoroFree->moveBefore(InsertPt);
406 CGF.Builder.SetInsertPoint(InsertPt);
407
408 // Add if (auto *mem = coro.free) Deallocate;
409 auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
410 auto *Cond = CGF.Builder.CreateICmpNE(CoroFree, NullPtr);
411 CGF.Builder.CreateCondBr(Cond, FreeBB, AfterFreeBB);
412
413 // No longer need old terminator.
414 InsertPt->eraseFromParent();
415 CGF.Builder.SetInsertPoint(AfterFreeBB);
416 }
417 explicit CallCoroDelete(Stmt *DeallocStmt) : Deallocate(DeallocStmt) {}
418};
419}
420
421namespace {
422struct GetReturnObjectManager {
423 CodeGenFunction &CGF;
424 CGBuilderTy &Builder;
425 const CoroutineBodyStmt &S;
426
427 Address GroActiveFlag;
428 CodeGenFunction::AutoVarEmission GroEmission;
429
430 GetReturnObjectManager(CodeGenFunction &CGF, const CoroutineBodyStmt &S)
431 : CGF(CGF), Builder(CGF.Builder), S(S), GroActiveFlag(Address::invalid()),
432 GroEmission(CodeGenFunction::AutoVarEmission::invalid()) {}
433
434 // The gro variable has to outlive coroutine frame and coroutine promise, but,
435 // it can only be initialized after coroutine promise was created, thus, we
436 // split its emission in two parts. EmitGroAlloca emits an alloca and sets up
437 // cleanups. Later when coroutine promise is available we initialize the gro
438 // and sets the flag that the cleanup is now active.
439
440 void EmitGroAlloca() {
441 auto *GroDeclStmt = dyn_cast<DeclStmt>(S.getResultDecl());
442 if (!GroDeclStmt) {
443 // If get_return_object returns void, no need to do an alloca.
444 return;
445 }
446
447 auto *GroVarDecl = cast<VarDecl>(GroDeclStmt->getSingleDecl());
448
449 // Set GRO flag that it is not initialized yet
450 GroActiveFlag =
451 CGF.CreateTempAlloca(Builder.getInt1Ty(), CharUnits::One(), "gro.active");
452 Builder.CreateStore(Builder.getFalse(), GroActiveFlag);
453
454 GroEmission = CGF.EmitAutoVarAlloca(*GroVarDecl);
455
456 // Remember the top of EHStack before emitting the cleanup.
457 auto old_top = CGF.EHStack.stable_begin();
458 CGF.EmitAutoVarCleanups(GroEmission);
459 auto top = CGF.EHStack.stable_begin();
460
461 // Make the cleanup conditional on gro.active
462 for (auto b = CGF.EHStack.find(top), e = CGF.EHStack.find(old_top);
463 b != e; b++) {
464 if (auto *Cleanup = dyn_cast<EHCleanupScope>(&*b)) {
465 assert(!Cleanup->hasActiveFlag() && "cleanup already has active flag?")((!Cleanup->hasActiveFlag() && "cleanup already has active flag?"
) ? static_cast<void> (0) : __assert_fail ("!Cleanup->hasActiveFlag() && \"cleanup already has active flag?\""
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn306458/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 465, __PRETTY_FUNCTION__));
466 Cleanup->setActiveFlag(GroActiveFlag);
467 Cleanup->setTestFlagInEHCleanup();
468 Cleanup->setTestFlagInNormalCleanup();
469 }
470 }
471 }
472
473 void EmitGroInit() {
474 if (!GroActiveFlag.isValid()) {
475 // No Gro variable was allocated. Simply emit the call to
476 // get_return_object.
477 CGF.EmitStmt(S.getResultDecl());
478 return;
479 }
480
481 CGF.EmitAutoVarInit(GroEmission);
482 Builder.CreateStore(Builder.getTrue(), GroActiveFlag);
483 }
484};
485}
486
487static void emitBodyAndFallthrough(CodeGenFunction &CGF,
488 const CoroutineBodyStmt &S, Stmt *Body) {
489 CGF.EmitStmt(Body);
490 const bool CanFallthrough = CGF.Builder.GetInsertBlock();
491 if (CanFallthrough)
492 if (Stmt *OnFallthrough = S.getFallthroughHandler())
493 CGF.EmitStmt(OnFallthrough);
494}
495
496void CodeGenFunction::EmitCoroutineBody(const CoroutineBodyStmt &S) {
497 auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
498 auto &TI = CGM.getContext().getTargetInfo();
499 unsigned NewAlign = TI.getNewAlign() / TI.getCharWidth();
500
501 auto *EntryBB = Builder.GetInsertBlock();
502 auto *AllocBB = createBasicBlock("coro.alloc");
503 auto *InitBB = createBasicBlock("coro.init");
504 auto *FinalBB = createBasicBlock("coro.final");
505 auto *RetBB = createBasicBlock("coro.ret");
506
507 auto *CoroId = Builder.CreateCall(
508 CGM.getIntrinsic(llvm::Intrinsic::coro_id),
509 {Builder.getInt32(NewAlign), NullPtr, NullPtr, NullPtr});
510 createCoroData(*this, CurCoro, CoroId);
511 CurCoro.Data->SuspendBB = RetBB;
512
513 // Backend is allowed to elide memory allocations, to help it, emit
514 // auto mem = coro.alloc() ? 0 : ... allocation code ...;
515 auto *CoroAlloc = Builder.CreateCall(
516 CGM.getIntrinsic(llvm::Intrinsic::coro_alloc), {CoroId});
517
518 Builder.CreateCondBr(CoroAlloc, AllocBB, InitBB);
519
520 EmitBlock(AllocBB);
521 auto *AllocateCall = EmitScalarExpr(S.getAllocate());
522 auto *AllocOrInvokeContBB = Builder.GetInsertBlock();
523
524 // Handle allocation failure if 'ReturnStmtOnAllocFailure' was provided.
525 if (auto *RetOnAllocFailure = S.getReturnStmtOnAllocFailure()) {
526 auto *RetOnFailureBB = createBasicBlock("coro.ret.on.failure");
527
528 // See if allocation was successful.
529 auto *NullPtr = llvm::ConstantPointerNull::get(Int8PtrTy);
530 auto *Cond = Builder.CreateICmpNE(AllocateCall, NullPtr);
531 Builder.CreateCondBr(Cond, InitBB, RetOnFailureBB);
532
533 // If not, return OnAllocFailure object.
534 EmitBlock(RetOnFailureBB);
535 EmitStmt(RetOnAllocFailure);
536 }
537 else {
538 Builder.CreateBr(InitBB);
539 }
540
541 EmitBlock(InitBB);
542
543 // Pass the result of the allocation to coro.begin.
544 auto *Phi = Builder.CreatePHI(VoidPtrTy, 2);
545 Phi->addIncoming(NullPtr, EntryBB);
546 Phi->addIncoming(AllocateCall, AllocOrInvokeContBB);
547 auto *CoroBegin = Builder.CreateCall(
548 CGM.getIntrinsic(llvm::Intrinsic::coro_begin), {CoroId, Phi});
549 CurCoro.Data->CoroBegin = CoroBegin;
550
551 GetReturnObjectManager GroManager(*this, S);
552 GroManager.EmitGroAlloca();
553
554 CurCoro.Data->CleanupJD = getJumpDestInCurrentScope(RetBB);
555 {
556 ParamReferenceReplacerRAII ParamReplacer(LocalDeclMap);
557 CodeGenFunction::RunCleanupsScope ResumeScope(*this);
558 EHStack.pushCleanup<CallCoroDelete>(NormalAndEHCleanup, S.getDeallocate());
559
560 // Create parameter copies. We do it before creating a promise, since an
561 // evolution of coroutine TS may allow promise constructor to observe
562 // parameter copies.
563 for (auto *PM : S.getParamMoves()) {
564 EmitStmt(PM);
565 ParamReplacer.addCopy(cast<DeclStmt>(PM));
566 // TODO: if(CoroParam(...)) need to surround ctor and dtor
567 // for the copy, so that llvm can elide it if the copy is
568 // not needed.
569 }
570
571 EmitStmt(S.getPromiseDeclStmt());
572
573 Address PromiseAddr = GetAddrOfLocalVar(S.getPromiseDecl());
574 auto *PromiseAddrVoidPtr =
575 new llvm::BitCastInst(PromiseAddr.getPointer(), VoidPtrTy, "", CoroId);
576 // Update CoroId to refer to the promise. We could not do it earlier because
577 // promise local variable was not emitted yet.
578 CoroId->setArgOperand(1, PromiseAddrVoidPtr);
579
580 // Now we have the promise, initialize the GRO
581 GroManager.EmitGroInit();
582
583 EHStack.pushCleanup<CallCoroEnd>(EHCleanup);
584
585 CurCoro.Data->CurrentAwaitKind = AwaitKind::Init;
586 EmitStmt(S.getInitSuspendStmt());
587 CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
588
589 CurCoro.Data->CurrentAwaitKind = AwaitKind::Normal;
590
591 if (auto *OnException = S.getExceptionHandler()) {
592 auto Loc = S.getLocStart();
593 CXXCatchStmt Catch(Loc, /*exDecl=*/nullptr, OnException);
594 auto *TryStmt = CXXTryStmt::Create(getContext(), Loc, S.getBody(), &Catch);
595
596 EnterCXXTryStmt(*TryStmt);
597 emitBodyAndFallthrough(*this, S, TryStmt->getTryBlock());
598 ExitCXXTryStmt(*TryStmt);
599 }
600 else {
601 emitBodyAndFallthrough(*this, S, S.getBody());
602 }
603
604 // See if we need to generate final suspend.
605 const bool CanFallthrough = Builder.GetInsertBlock();
606 const bool HasCoreturns = CurCoro.Data->CoreturnCount > 0;
607 if (CanFallthrough || HasCoreturns) {
608 EmitBlock(FinalBB);
609 CurCoro.Data->CurrentAwaitKind = AwaitKind::Final;
610 EmitStmt(S.getFinalSuspendStmt());
611 } else {
612 // We don't need FinalBB. Emit it to make sure the block is deleted.
613 EmitBlock(FinalBB, /*IsFinished=*/true);
614 }
615 }
616
617 EmitBlock(RetBB);
618 // Emit coro.end before getReturnStmt (and parameter destructors), since
619 // resume and destroy parts of the coroutine should not include them.
620 llvm::Function *CoroEnd = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
621 Builder.CreateCall(CoroEnd, {NullPtr, Builder.getFalse()});
622
623 if (Stmt *Ret = S.getReturnStmt())
624 EmitStmt(Ret);
625}
626
627// Emit coroutine intrinsic and patch up arguments of the token type.
628RValue CodeGenFunction::EmitCoroutineIntrinsic(const CallExpr *E,
629 unsigned int IID) {
630 SmallVector<llvm::Value *, 8> Args;
631 switch (IID) {
632 default:
633 break;
634 // The coro.frame builtin is replaced with an SSA value of the coro.begin
635 // intrinsic.
636 case llvm::Intrinsic::coro_frame: {
637 if (CurCoro.Data && CurCoro.Data->CoroBegin) {
638 return RValue::get(CurCoro.Data->CoroBegin);
639 }
640 CGM.Error(E->getLocStart(), "this builtin expect that __builtin_coro_begin "
641 "has been used earlier in this function");
642 auto NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
643 return RValue::get(NullPtr);
644 }
645 // The following three intrinsics take a token parameter referring to a token
646 // returned by earlier call to @llvm.coro.id. Since we cannot represent it in
647 // builtins, we patch it up here.
648 case llvm::Intrinsic::coro_alloc:
649 case llvm::Intrinsic::coro_begin:
650 case llvm::Intrinsic::coro_free: {
651 if (CurCoro.Data && CurCoro.Data->CoroId) {
652 Args.push_back(CurCoro.Data->CoroId);
653 break;
654 }
655 CGM.Error(E->getLocStart(), "this builtin expect that __builtin_coro_id has"
656 " been used earlier in this function");
657 // Fallthrough to the next case to add TokenNone as the first argument.
658 LLVM_FALLTHROUGH[[clang::fallthrough]];
659 }
660 // @llvm.coro.suspend takes a token parameter. Add token 'none' as the first
661 // argument.
662 case llvm::Intrinsic::coro_suspend:
663 Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
664 break;
665 }
666 for (auto &Arg : E->arguments())
667 Args.push_back(EmitScalarExpr(Arg));
668
669 llvm::Value *F = CGM.getIntrinsic(IID);
670 llvm::CallInst *Call = Builder.CreateCall(F, Args);
671
672 // Note: The following code is to enable to emit coro.id and coro.begin by
673 // hand to experiment with coroutines in C.
674 // If we see @llvm.coro.id remember it in the CoroData. We will update
675 // coro.alloc, coro.begin and coro.free intrinsics to refer to it.
676 if (IID == llvm::Intrinsic::coro_id) {
677 createCoroData(*this, CurCoro, Call, E);
678 }
679 else if (IID == llvm::Intrinsic::coro_begin) {
680 if (CurCoro.Data)
681 CurCoro.Data->CoroBegin = Call;
682 }
683 else if (IID == llvm::Intrinsic::coro_free) {
684 // Remember the last coro_free as we need it to build the conditional
685 // deletion of the coroutine frame.
686 if (CurCoro.Data)
687 CurCoro.Data->LastCoroFree = Call;
688 }
689 return RValue::get(Call);
690}