Bug Summary

File:tools/clang/lib/CodeGen/CGCoroutine.cpp
Warning:line 87, column 21
Called C++ object pointer is null

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) {
3
Taking true branch
86 if (CurCoro.Data->CoroIdExpr)
4
Assuming the condition is true
5
Taking true branch
87 CGF.CGM.Error(CoroIdExpr->getLocStart(),
6
Called C++ object pointer is null
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?"
, "/build/llvm-toolchain-snapshot-6.0~svn318601/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 && 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);
191 }
192
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)});
199
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);
204
205 // Emit cleanup for this suspend point.
206 CGF.EmitBlock(CleanupBlock);
207 CGF.EmitBranchThroughCleanup(Coro.CleanupJD);
208
209 // Emit await_resume expression.
210 CGF.EmitBlock(ReadyBlock);
211 LValueOrRValue Res;
212 if (forLValue)
213 Res.LV = CGF.EmitLValue(S.getResumeExpr());
214 else
215 Res.RV = CGF.EmitAnyExpr(S.getResumeExpr(), aggSlot, ignoreResult);
216 return Res;
217}
218
219RValue CodeGenFunction::EmitCoawaitExpr(const CoawaitExpr &E,
220 AggValueSlot aggSlot,
221 bool ignoreResult) {
222 return emitSuspendExpression(*this, *CurCoro.Data, E,
223 CurCoro.Data->CurrentAwaitKind, aggSlot,
224 ignoreResult, /*forLValue*/false).RV;
225}
226RValue CodeGenFunction::EmitCoyieldExpr(const CoyieldExpr &E,
227 AggValueSlot aggSlot,
228 bool ignoreResult) {
229 return emitSuspendExpression(*this, *CurCoro.Data, E, AwaitKind::Yield,
230 aggSlot, ignoreResult, /*forLValue*/false).RV;
231}
232
233void 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);
240 EmitIgnoredExpr(RV);
241 }
242 EmitStmt(S.getPromiseCall());
243 EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
244}
245
246
247#ifndef NDEBUG
248static 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
252 // a MemberCallExpr?
253 assert(isa<CallExpr>(RE) && "unexpected suspend expression type")(static_cast <bool> (isa<CallExpr>(RE) &&
"unexpected suspend expression type") ? void (0) : __assert_fail
("isa<CallExpr>(RE) && \"unexpected suspend expression type\""
, "/build/llvm-toolchain-snapshot-6.0~svn318601/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 253, __extension__ __PRETTY_FUNCTION__))
;
254 return cast<CallExpr>(RE)->getCallReturnType(Ctx);
255}
256#endif
257
258LValue
259CodeGenFunction::EmitCoawaitLValue(const CoawaitExpr *E) {
260 assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&(static_cast <bool> (getCoroutineSuspendExprReturnType(
getContext(), E)->isReferenceType() && "Can't have a scalar return unless the return type is a "
"reference type!") ? void (0) : __assert_fail ("getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() && \"Can't have a scalar return unless the return type is a \" \"reference type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn318601/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 262, __extension__ __PRETTY_FUNCTION__))
261 "Can't have a scalar return unless the return type is a "(static_cast <bool> (getCoroutineSuspendExprReturnType(
getContext(), E)->isReferenceType() && "Can't have a scalar return unless the return type is a "
"reference type!") ? void (0) : __assert_fail ("getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() && \"Can't have a scalar return unless the return type is a \" \"reference type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn318601/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 262, __extension__ __PRETTY_FUNCTION__))
262 "reference type!")(static_cast <bool> (getCoroutineSuspendExprReturnType(
getContext(), E)->isReferenceType() && "Can't have a scalar return unless the return type is a "
"reference type!") ? void (0) : __assert_fail ("getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() && \"Can't have a scalar return unless the return type is a \" \"reference type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn318601/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 262, __extension__ __PRETTY_FUNCTION__))
;
263 return emitSuspendExpression(*this, *CurCoro.Data, *E,
264 CurCoro.Data->CurrentAwaitKind, AggValueSlot::ignored(),
265 /*ignoreResult*/false, /*forLValue*/true).LV;
266}
267
268LValue
269CodeGenFunction::EmitCoyieldLValue(const CoyieldExpr *E) {
270 assert(getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() &&(static_cast <bool> (getCoroutineSuspendExprReturnType(
getContext(), E)->isReferenceType() && "Can't have a scalar return unless the return type is a "
"reference type!") ? void (0) : __assert_fail ("getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() && \"Can't have a scalar return unless the return type is a \" \"reference type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn318601/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 272, __extension__ __PRETTY_FUNCTION__))
271 "Can't have a scalar return unless the return type is a "(static_cast <bool> (getCoroutineSuspendExprReturnType(
getContext(), E)->isReferenceType() && "Can't have a scalar return unless the return type is a "
"reference type!") ? void (0) : __assert_fail ("getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() && \"Can't have a scalar return unless the return type is a \" \"reference type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn318601/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 272, __extension__ __PRETTY_FUNCTION__))
272 "reference type!")(static_cast <bool> (getCoroutineSuspendExprReturnType(
getContext(), E)->isReferenceType() && "Can't have a scalar return unless the return type is a "
"reference type!") ? void (0) : __assert_fail ("getCoroutineSuspendExprReturnType(getContext(), E)->isReferenceType() && \"Can't have a scalar return unless the return type is a \" \"reference type!\""
, "/build/llvm-toolchain-snapshot-6.0~svn318601/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 272, __extension__ __PRETTY_FUNCTION__))
;
273 return emitSuspendExpression(*this, *CurCoro.Data, *E,
274 AwaitKind::Yield, AggValueSlot::ignored(),
275 /*ignoreResult*/false, /*forLValue*/true).LV;
276}
277
278// Hunts for the parameter reference in the parameter copy/move declaration.
279namespace {
280struct GetParamRef : public StmtVisitor<GetParamRef> {
281public:
282 DeclRefExpr *Expr = nullptr;
283 GetParamRef() {}
284 void VisitDeclRefExpr(DeclRefExpr *E) {
285 assert(Expr == nullptr && "multilple declref in param move")(static_cast <bool> (Expr == nullptr && "multilple declref in param move"
) ? void (0) : __assert_fail ("Expr == nullptr && \"multilple declref in param move\""
, "/build/llvm-toolchain-snapshot-6.0~svn318601/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 285, __extension__ __PRETTY_FUNCTION__))
;
286 Expr = E;
287 }
288 void VisitStmt(Stmt *S) {
289 for (auto *C : S->children()) {
290 if (C)
291 Visit(C);
292 }
293 }
294};
295}
296
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
299// its destructor.
300
301namespace {
302 struct ParamReferenceReplacerRAII {
303 CodeGenFunction::DeclMapTy SavedLocals;
304 CodeGenFunction::DeclMapTy& LocalDeclMap;
305
306 ParamReferenceReplacerRAII(CodeGenFunction::DeclMapTy &LocalDeclMap)
307 : LocalDeclMap(LocalDeclMap) {}
308
309 void addCopy(DeclStmt const *PM) {
310 // Figure out what param it refers to.
311
312 assert(PM->isSingleDecl())(static_cast <bool> (PM->isSingleDecl()) ? void (0) :
__assert_fail ("PM->isSingleDecl()", "/build/llvm-toolchain-snapshot-6.0~svn318601/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 312, __extension__ __PRETTY_FUNCTION__))
;
313 VarDecl const*VD = static_cast<VarDecl const*>(PM->getSingleDecl());
314 Expr const *InitExpr = VD->getInit();
315 GetParamRef Visitor;
316 Visitor.Visit(const_cast<Expr*>(InitExpr));
317 assert(Visitor.Expr)(static_cast <bool> (Visitor.Expr) ? void (0) : __assert_fail
("Visitor.Expr", "/build/llvm-toolchain-snapshot-6.0~svn318601/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 317, __extension__ __PRETTY_FUNCTION__))
;
318 auto *DREOrig = cast<DeclRefExpr>(Visitor.Expr);
319 auto *PD = DREOrig->getDecl();
320
321 auto it = LocalDeclMap.find(PD);
322 assert(it != LocalDeclMap.end() && "parameter is not found")(static_cast <bool> (it != LocalDeclMap.end() &&
"parameter is not found") ? void (0) : __assert_fail ("it != LocalDeclMap.end() && \"parameter is not found\""
, "/build/llvm-toolchain-snapshot-6.0~svn318601/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 322, __extension__ __PRETTY_FUNCTION__))
;
323 SavedLocals.insert({ PD, it->second });
324
325 auto copyIt = LocalDeclMap.find(VD);
326 assert(copyIt != LocalDeclMap.end() && "parameter copy is not found")(static_cast <bool> (copyIt != LocalDeclMap.end() &&
"parameter copy is not found") ? void (0) : __assert_fail ("copyIt != LocalDeclMap.end() && \"parameter copy is not found\""
, "/build/llvm-toolchain-snapshot-6.0~svn318601/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 326, __extension__ __PRETTY_FUNCTION__))
;
327 it->second = copyIt->getSecond();
328 }
329
330 ~ParamReferenceReplacerRAII() {
331 for (auto&& SavedLocal : SavedLocals) {
332 LocalDeclMap.insert({SavedLocal.first, SavedLocal.second});
333 }
334 }
335 };
336}
337
338// For WinEH exception representation backend needs to know what funclet coro.end
339// belongs to. That information is passed in a funclet bundle.
340static SmallVector<llvm::OperandBundleDef, 1>
341getBundlesForCoroEnd(CodeGenFunction &CGF) {
342 SmallVector<llvm::OperandBundleDef, 1> BundleList;
343
344 if (llvm::Instruction *EHPad = CGF.CurrentFuncletPad)
345 BundleList.emplace_back("funclet", EHPad);
346
347 return BundleList;
348}
349
350namespace {
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.
354struct CallCoroEnd final : public EHScopeStack::Cleanup {
355 void Emit(CodeGenFunction &CGF, Flags flags) override {
356 auto &CGM = CGF.CGM;
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);
370 }
371 }
372};
373}
374
375namespace {
376// Make sure to call coro.delete on scope exit.
377struct CallCoroDelete final : public EHScopeStack::Cleanup {
378 Stmt *Deallocate;
379
380 // Emit "if (coro.free(CoroId, CoroBegin)) Deallocate;"
381
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
386 // multiple times.
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
390 // call.
391 BasicBlock *SaveInsertBlock = CGF.Builder.GetInsertBlock();
392
393 auto *FreeBB = CGF.createBasicBlock("coro.free");
394 CGF.EmitBlock(FreeBB);
395 CGF.EmitStmt(Deallocate);
396
397 auto *AfterFreeBB = CGF.createBasicBlock("after.coro.free");
398 CGF.EmitBlock(AfterFreeBB);
399
400 // We should have captured coro.free from the emission of deallocate.
401 auto *CoroFree = CGF.CurCoro.Data->LastCoroFree;
402 if (!CoroFree) {
403 CGF.CGM.Error(Deallocate->getLocStart(),
404 "Deallocation expressoin does not refer to coro.free");
405 return;
406 }
407
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);
412
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);
417
418 // No longer need old terminator.
419 InsertPt->eraseFromParent();
420 CGF.Builder.SetInsertPoint(AfterFreeBB);
421 }
422 explicit CallCoroDelete(Stmt *DeallocStmt) : Deallocate(DeallocStmt) {}
423};
424}
425
426namespace {
427struct GetReturnObjectManager {
428 CodeGenFunction &CGF;
429 CGBuilderTy &Builder;
430 const CoroutineBodyStmt &S;
431
432 Address GroActiveFlag;
433 CodeGenFunction::AutoVarEmission GroEmission;
434
435 GetReturnObjectManager(CodeGenFunction &CGF, const CoroutineBodyStmt &S)
436 : CGF(CGF), Builder(CGF.Builder), S(S), GroActiveFlag(Address::invalid()),
437 GroEmission(CodeGenFunction::AutoVarEmission::invalid()) {}
438
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.
444
445 void EmitGroAlloca() {
446 auto *GroDeclStmt = dyn_cast<DeclStmt>(S.getResultDecl());
447 if (!GroDeclStmt) {
448 // If get_return_object returns void, no need to do an alloca.
449 return;
450 }
451
452 auto *GroVarDecl = cast<VarDecl>(GroDeclStmt->getSingleDecl());
453
454 // Set GRO flag that it is not initialized yet
455 GroActiveFlag =
456 CGF.CreateTempAlloca(Builder.getInt1Ty(), CharUnits::One(), "gro.active");
457 Builder.CreateStore(Builder.getFalse(), GroActiveFlag);
458
459 GroEmission = CGF.EmitAutoVarAlloca(*GroVarDecl);
460
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();
465
466 // Make the cleanup conditional on gro.active
467 for (auto b = CGF.EHStack.find(top), e = CGF.EHStack.find(old_top);
468 b != e; b++) {
469 if (auto *Cleanup = dyn_cast<EHCleanupScope>(&*b)) {
470 assert(!Cleanup->hasActiveFlag() && "cleanup already has active flag?")(static_cast <bool> (!Cleanup->hasActiveFlag() &&
"cleanup already has active flag?") ? void (0) : __assert_fail
("!Cleanup->hasActiveFlag() && \"cleanup already has active flag?\""
, "/build/llvm-toolchain-snapshot-6.0~svn318601/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 470, __extension__ __PRETTY_FUNCTION__))
;
471 Cleanup->setActiveFlag(GroActiveFlag);
472 Cleanup->setTestFlagInEHCleanup();
473 Cleanup->setTestFlagInNormalCleanup();
474 }
475 }
476 }
477
478 void EmitGroInit() {
479 if (!GroActiveFlag.isValid()) {
480 // No Gro variable was allocated. Simply emit the call to
481 // get_return_object.
482 CGF.EmitStmt(S.getResultDecl());
483 return;
484 }
485
486 CGF.EmitAutoVarInit(GroEmission);
487 Builder.CreateStore(Builder.getTrue(), GroActiveFlag);
488 }
489};
490}
491
492static void emitBodyAndFallthrough(CodeGenFunction &CGF,
493 const CoroutineBodyStmt &S, Stmt *Body) {
494 CGF.EmitStmt(Body);
495 const bool CanFallthrough = CGF.Builder.GetInsertBlock();
496 if (CanFallthrough)
497 if (Stmt *OnFallthrough = S.getFallthroughHandler())
498 CGF.EmitStmt(OnFallthrough);
499}
500
501void 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();
505
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");
511
512 auto *CoroId = Builder.CreateCall(
513 CGM.getIntrinsic(llvm::Intrinsic::coro_id),
514 {Builder.getInt32(NewAlign), NullPtr, NullPtr, NullPtr});
515 createCoroData(*this, CurCoro, CoroId);
1
Passing null pointer value via 4th parameter 'CoroIdExpr'
2
Calling 'createCoroData'
516 CurCoro.Data->SuspendBB = RetBB;
517
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});
522
523 Builder.CreateCondBr(CoroAlloc, AllocBB, InitBB);
524
525 EmitBlock(AllocBB);
526 auto *AllocateCall = EmitScalarExpr(S.getAllocate());
527 auto *AllocOrInvokeContBB = Builder.GetInsertBlock();
528
529 // Handle allocation failure if 'ReturnStmtOnAllocFailure' was provided.
530 if (auto *RetOnAllocFailure = S.getReturnStmtOnAllocFailure()) {
531 auto *RetOnFailureBB = createBasicBlock("coro.ret.on.failure");
532
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);
537
538 // If not, return OnAllocFailure object.
539 EmitBlock(RetOnFailureBB);
540 EmitStmt(RetOnAllocFailure);
541 }
542 else {
543 Builder.CreateBr(InitBB);
544 }
545
546 EmitBlock(InitBB);
547
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;
555
556 GetReturnObjectManager GroManager(*this, S);
557 GroManager.EmitGroAlloca();
558
559 CurCoro.Data->CleanupJD = getJumpDestInCurrentScope(RetBB);
560 {
561 ParamReferenceReplacerRAII ParamReplacer(LocalDeclMap);
562 CodeGenFunction::RunCleanupsScope ResumeScope(*this);
563 EHStack.pushCleanup<CallCoroDelete>(NormalAndEHCleanup, S.getDeallocate());
564
565 // Create parameter copies. We do it before creating a promise, since an
566 // evolution of coroutine TS may allow promise constructor to observe
567 // parameter copies.
568 for (auto *PM : S.getParamMoves()) {
569 EmitStmt(PM);
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
573 // not needed.
574 }
575
576 EmitStmt(S.getPromiseDeclStmt());
577
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);
584
585 // Now we have the promise, initialize the GRO
586 GroManager.EmitGroInit();
587
588 EHStack.pushCleanup<CallCoroEnd>(EHCleanup);
589
590 CurCoro.Data->CurrentAwaitKind = AwaitKind::Init;
591 EmitStmt(S.getInitSuspendStmt());
592 CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
593
594 CurCoro.Data->CurrentAwaitKind = AwaitKind::Normal;
595
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);
600
601 EnterCXXTryStmt(*TryStmt);
602 emitBodyAndFallthrough(*this, S, TryStmt->getTryBlock());
603 ExitCXXTryStmt(*TryStmt);
604 }
605 else {
606 emitBodyAndFallthrough(*this, S, S.getBody());
607 }
608
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) {
613 EmitBlock(FinalBB);
614 CurCoro.Data->CurrentAwaitKind = AwaitKind::Final;
615 EmitStmt(S.getFinalSuspendStmt());
616 } else {
617 // We don't need FinalBB. Emit it to make sure the block is deleted.
618 EmitBlock(FinalBB, /*IsFinished=*/true);
619 }
620 }
621
622 EmitBlock(RetBB);
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()});
627
628 if (Stmt *Ret = S.getReturnStmt())
629 EmitStmt(Ret);
630}
631
632// Emit coroutine intrinsic and patch up arguments of the token type.
633RValue CodeGenFunction::EmitCoroutineIntrinsic(const CallExpr *E,
634 unsigned int IID) {
635 SmallVector<llvm::Value *, 8> Args;
636 switch (IID) {
637 default:
638 break;
639 // The coro.frame builtin is replaced with an SSA value of the coro.begin
640 // intrinsic.
641 case llvm::Intrinsic::coro_frame: {
642 if (CurCoro.Data && CurCoro.Data->CoroBegin) {
643 return RValue::get(CurCoro.Data->CoroBegin);
644 }
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);
649 }
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);
658 break;
659 }
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.
663 LLVM_FALLTHROUGH[[clang::fallthrough]];
664 }
665 // @llvm.coro.suspend takes a token parameter. Add token 'none' as the first
666 // argument.
667 case llvm::Intrinsic::coro_suspend:
668 Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
669 break;
670 }
671 for (auto &Arg : E->arguments())
672 Args.push_back(EmitScalarExpr(Arg));
673
674 llvm::Value *F = CGM.getIntrinsic(IID);
675 llvm::CallInst *Call = Builder.CreateCall(F, Args);
676
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);
683 }
684 else if (IID == llvm::Intrinsic::coro_begin) {
685 if (CurCoro.Data)
686 CurCoro.Data->CoroBegin = Call;
687 }
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.
691 if (CurCoro.Data)
692 CurCoro.Data->LastCoroFree = Call;
693 }
694 return RValue::get(Call);
695}