Bug Summary

File:tools/clang/lib/CodeGen/CGCoroutine.cpp
Warning:line 207, column 5
Value stored to 'SuspendBlock' is never read

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name CGCoroutine.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mthread-model posix -relaxed-aliasing -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -momit-leaf-frame-pointer -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-9/lib/clang/9.0.0 -D CLANG_VENDOR="Debian " -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-9~svn362543/build-llvm/tools/clang/lib/CodeGen -I /build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen -I /build/llvm-toolchain-snapshot-9~svn362543/tools/clang/include -I /build/llvm-toolchain-snapshot-9~svn362543/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-9~svn362543/build-llvm/include -I /build/llvm-toolchain-snapshot-9~svn362543/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/include/clang/9.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-9/lib/clang/9.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++11 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-9~svn362543/build-llvm/tools/clang/lib/CodeGen -fdebug-prefix-map=/build/llvm-toolchain-snapshot-9~svn362543=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fobjc-runtime=gcc -fno-common -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -o /tmp/scan-build-2019-06-05-060531-1271-1 -x c++ /build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp -faddrsig
1//===----- CGCoroutine.cpp - Emit LLVM Code for C++ coroutines ------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This contains code dealing with C++ code generation of coroutines.
10//
11//===----------------------------------------------------------------------===//
12
13#include "CGCleanup.h"
14#include "CodeGenFunction.h"
15#include "llvm/ADT/ScopeExit.h"
16#include "clang/AST/StmtCXX.h"
17#include "clang/AST/StmtVisitor.h"
18
19using namespace clang;
20using namespace CodeGen;
21
22using llvm::Value;
23using llvm::BasicBlock;
24
25namespace {
26enum class AwaitKind { Init, Normal, Yield, Final };
27static constexpr llvm::StringLiteral AwaitKindStr[] = {"init", "await", "yield",
28 "final"};
29}
30
31struct clang::CodeGen::CGCoroData {
32 // What is the current await expression kind and how many
33 // await/yield expressions were encountered so far.
34 // These are used to generate pretty labels for await expressions in LLVM IR.
35 AwaitKind CurrentAwaitKind = AwaitKind::Init;
36 unsigned AwaitNum = 0;
37 unsigned YieldNum = 0;
38
39 // How many co_return statements are in the coroutine. Used to decide whether
40 // we need to add co_return; equivalent at the end of the user authored body.
41 unsigned CoreturnCount = 0;
42
43 // A branch to this block is emitted when coroutine needs to suspend.
44 llvm::BasicBlock *SuspendBB = nullptr;
45
46 // The promise type's 'unhandled_exception' handler, if it defines one.
47 Stmt *ExceptionHandler = nullptr;
48
49 // A temporary i1 alloca that stores whether 'await_resume' threw an
50 // exception. If it did, 'true' is stored in this variable, and the coroutine
51 // body must be skipped. If the promise type does not define an exception
52 // handler, this is null.
53 llvm::Value *ResumeEHVar = nullptr;
54
55 // Stores the jump destination just before the coroutine memory is freed.
56 // This is the destination that every suspend point jumps to for the cleanup
57 // branch.
58 CodeGenFunction::JumpDest CleanupJD;
59
60 // Stores the jump destination just before the final suspend. The co_return
61 // statements jumps to this point after calling return_xxx promise member.
62 CodeGenFunction::JumpDest FinalJD;
63
64 // Stores the llvm.coro.id emitted in the function so that we can supply it
65 // as the first argument to coro.begin, coro.alloc and coro.free intrinsics.
66 // Note: llvm.coro.id returns a token that cannot be directly expressed in a
67 // builtin.
68 llvm::CallInst *CoroId = nullptr;
69
70 // Stores the llvm.coro.begin emitted in the function so that we can replace
71 // all coro.frame intrinsics with direct SSA value of coro.begin that returns
72 // the address of the coroutine frame of the current coroutine.
73 llvm::CallInst *CoroBegin = nullptr;
74
75 // Stores the last emitted coro.free for the deallocate expressions, we use it
76 // to wrap dealloc code with if(auto mem = coro.free) dealloc(mem).
77 llvm::CallInst *LastCoroFree = nullptr;
78
79 // If coro.id came from the builtin, remember the expression to give better
80 // diagnostic. If CoroIdExpr is nullptr, the coro.id was created by
81 // EmitCoroutineBody.
82 CallExpr const *CoroIdExpr = nullptr;
83};
84
85// Defining these here allows to keep CGCoroData private to this file.
86clang::CodeGen::CodeGenFunction::CGCoroInfo::CGCoroInfo() {}
87CodeGenFunction::CGCoroInfo::~CGCoroInfo() {}
88
89static void createCoroData(CodeGenFunction &CGF,
90 CodeGenFunction::CGCoroInfo &CurCoro,
91 llvm::CallInst *CoroId,
92 CallExpr const *CoroIdExpr = nullptr) {
93 if (CurCoro.Data) {
94 if (CurCoro.Data->CoroIdExpr)
95 CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
96 "only one __builtin_coro_id can be used in a function");
97 else if (CoroIdExpr)
98 CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
99 "__builtin_coro_id shall not be used in a C++ coroutine");
100 else
101 llvm_unreachable("EmitCoroutineBodyStatement called twice?")::llvm::llvm_unreachable_internal("EmitCoroutineBodyStatement called twice?"
, "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 101);
102
103 return;
104 }
105
106 CurCoro.Data = std::unique_ptr<CGCoroData>(new CGCoroData);
107 CurCoro.Data->CoroId = CoroId;
108 CurCoro.Data->CoroIdExpr = CoroIdExpr;
109}
110
111// Synthesize a pretty name for a suspend point.
112static SmallString<32> buildSuspendPrefixStr(CGCoroData &Coro, AwaitKind Kind) {
113 unsigned No = 0;
114 switch (Kind) {
115 case AwaitKind::Init:
116 case AwaitKind::Final:
117 break;
118 case AwaitKind::Normal:
119 No = ++Coro.AwaitNum;
120 break;
121 case AwaitKind::Yield:
122 No = ++Coro.YieldNum;
123 break;
124 }
125 SmallString<32> Prefix(AwaitKindStr[static_cast<unsigned>(Kind)]);
126 if (No > 1) {
127 Twine(No).toVector(Prefix);
128 }
129 return Prefix;
130}
131
132static bool memberCallExpressionCanThrow(const Expr *E) {
133 if (const auto *CE = dyn_cast<CXXMemberCallExpr>(E))
134 if (const auto *Proto =
135 CE->getMethodDecl()->getType()->getAs<FunctionProtoType>())
136 if (isNoexceptExceptionSpec(Proto->getExceptionSpecType()) &&
137 Proto->canThrow() == CT_Cannot)
138 return false;
139 return true;
140}
141
142// Emit suspend expression which roughly looks like:
143//
144// auto && x = CommonExpr();
145// if (!x.await_ready()) {
146// llvm_coro_save();
147// x.await_suspend(...); (*)
148// llvm_coro_suspend(); (**)
149// }
150// x.await_resume();
151//
152// where the result of the entire expression is the result of x.await_resume()
153//
154// (*) If x.await_suspend return type is bool, it allows to veto a suspend:
155// if (x.await_suspend(...))
156// llvm_coro_suspend();
157//
158// (**) llvm_coro_suspend() encodes three possible continuations as
159// a switch instruction:
160//
161// %where-to = call i8 @llvm.coro.suspend(...)
162// switch i8 %where-to, label %coro.ret [ ; jump to epilogue to suspend
163// i8 0, label %yield.ready ; go here when resumed
164// i8 1, label %yield.cleanup ; go here when destroyed
165// ]
166//
167// See llvm's docs/Coroutines.rst for more details.
168//
169namespace {
170 struct LValueOrRValue {
171 LValue LV;
172 RValue RV;
173 };
174}
175static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Coro,
176 CoroutineSuspendExpr const &S,
177 AwaitKind Kind, AggValueSlot aggSlot,
178 bool ignoreResult, bool forLValue) {
179 auto *E = S.getCommonExpr();
180
181 auto Binder =
182 CodeGenFunction::OpaqueValueMappingData::bind(CGF, S.getOpaqueValue(), E);
183 auto UnbindOnExit = llvm::make_scope_exit([&] { Binder.unbind(CGF); });
184
185 auto Prefix = buildSuspendPrefixStr(Coro, Kind);
186 BasicBlock *ReadyBlock = CGF.createBasicBlock(Prefix + Twine(".ready"));
187 BasicBlock *SuspendBlock = CGF.createBasicBlock(Prefix + Twine(".suspend"));
188 BasicBlock *CleanupBlock = CGF.createBasicBlock(Prefix + Twine(".cleanup"));
189
190 // If expression is ready, no need to suspend.
191 CGF.EmitBranchOnBoolExpr(S.getReadyExpr(), ReadyBlock, SuspendBlock, 0);
192
193 // Otherwise, emit suspend logic.
194 CGF.EmitBlock(SuspendBlock);
195
196 auto &Builder = CGF.Builder;
197 llvm::Function *CoroSave = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_save);
198 auto *NullPtr = llvm::ConstantPointerNull::get(CGF.CGM.Int8PtrTy);
199 auto *SaveCall = Builder.CreateCall(CoroSave, {NullPtr});
200
201 auto *SuspendRet = CGF.EmitScalarExpr(S.getSuspendExpr());
202 if (SuspendRet != nullptr && SuspendRet->getType()->isIntegerTy(1)) {
203 // Veto suspension if requested by bool returning await_suspend.
204 BasicBlock *RealSuspendBlock =
205 CGF.createBasicBlock(Prefix + Twine(".suspend.bool"));
206 CGF.Builder.CreateCondBr(SuspendRet, RealSuspendBlock, ReadyBlock);
207 SuspendBlock = RealSuspendBlock;
Value stored to 'SuspendBlock' is never read
208 CGF.EmitBlock(RealSuspendBlock);
209 }
210
211 // Emit the suspend point.
212 const bool IsFinalSuspend = (Kind == AwaitKind::Final);
213 llvm::Function *CoroSuspend =
214 CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_suspend);
215 auto *SuspendResult = Builder.CreateCall(
216 CoroSuspend, {SaveCall, Builder.getInt1(IsFinalSuspend)});
217
218 // Create a switch capturing three possible continuations.
219 auto *Switch = Builder.CreateSwitch(SuspendResult, Coro.SuspendBB, 2);
220 Switch->addCase(Builder.getInt8(0), ReadyBlock);
221 Switch->addCase(Builder.getInt8(1), CleanupBlock);
222
223 // Emit cleanup for this suspend point.
224 CGF.EmitBlock(CleanupBlock);
225 CGF.EmitBranchThroughCleanup(Coro.CleanupJD);
226
227 // Emit await_resume expression.
228 CGF.EmitBlock(ReadyBlock);
229
230 // Exception handling requires additional IR. If the 'await_resume' function
231 // is marked as 'noexcept', we avoid generating this additional IR.
232 CXXTryStmt *TryStmt = nullptr;
233 if (Coro.ExceptionHandler && Kind == AwaitKind::Init &&
234 memberCallExpressionCanThrow(S.getResumeExpr())) {
235 Coro.ResumeEHVar =
236 CGF.CreateTempAlloca(Builder.getInt1Ty(), Prefix + Twine("resume.eh"));
237 Builder.CreateFlagStore(true, Coro.ResumeEHVar);
238
239 auto Loc = S.getResumeExpr()->getExprLoc();
240 auto *Catch = new (CGF.getContext())
241 CXXCatchStmt(Loc, /*exDecl=*/nullptr, Coro.ExceptionHandler);
242 auto *TryBody =
243 CompoundStmt::Create(CGF.getContext(), S.getResumeExpr(), Loc, Loc);
244 TryStmt = CXXTryStmt::Create(CGF.getContext(), Loc, TryBody, Catch);
245 CGF.EnterCXXTryStmt(*TryStmt);
246 }
247
248 LValueOrRValue Res;
249 if (forLValue)
250 Res.LV = CGF.EmitLValue(S.getResumeExpr());
251 else
252 Res.RV = CGF.EmitAnyExpr(S.getResumeExpr(), aggSlot, ignoreResult);
253
254 if (TryStmt) {
255 Builder.CreateFlagStore(false, Coro.ResumeEHVar);
256 CGF.ExitCXXTryStmt(*TryStmt);
257 }
258
259 return Res;
260}
261
262RValue CodeGenFunction::EmitCoawaitExpr(const CoawaitExpr &E,
263 AggValueSlot aggSlot,
264 bool ignoreResult) {
265 return emitSuspendExpression(*this, *CurCoro.Data, E,
266 CurCoro.Data->CurrentAwaitKind, aggSlot,
267 ignoreResult, /*forLValue*/false).RV;
268}
269RValue CodeGenFunction::EmitCoyieldExpr(const CoyieldExpr &E,
270 AggValueSlot aggSlot,
271 bool ignoreResult) {
272 return emitSuspendExpression(*this, *CurCoro.Data, E, AwaitKind::Yield,
273 aggSlot, ignoreResult, /*forLValue*/false).RV;
274}
275
276void CodeGenFunction::EmitCoreturnStmt(CoreturnStmt const &S) {
277 ++CurCoro.Data->CoreturnCount;
278 const Expr *RV = S.getOperand();
279 if (RV && RV->getType()->isVoidType()) {
280 // Make sure to evaluate the expression of a co_return with a void
281 // expression for side effects.
282 RunCleanupsScope cleanupScope(*this);
283 EmitIgnoredExpr(RV);
284 }
285 EmitStmt(S.getPromiseCall());
286 EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
287}
288
289
290#ifndef NDEBUG
291static QualType getCoroutineSuspendExprReturnType(const ASTContext &Ctx,
292 const CoroutineSuspendExpr *E) {
293 const auto *RE = E->getResumeExpr();
294 // Is it possible for RE to be a CXXBindTemporaryExpr wrapping
295 // a MemberCallExpr?
296 assert(isa<CallExpr>(RE) && "unexpected suspend expression type")((isa<CallExpr>(RE) && "unexpected suspend expression type"
) ? static_cast<void> (0) : __assert_fail ("isa<CallExpr>(RE) && \"unexpected suspend expression type\""
, "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 296, __PRETTY_FUNCTION__));
297 return cast<CallExpr>(RE)->getCallReturnType(Ctx);
298}
299#endif
300
301LValue
302CodeGenFunction::EmitCoawaitLValue(const CoawaitExpr *E) {
303 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!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 305, __PRETTY_FUNCTION__))
304 "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!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 305, __PRETTY_FUNCTION__))
305 "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!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 305, __PRETTY_FUNCTION__));
306 return emitSuspendExpression(*this, *CurCoro.Data, *E,
307 CurCoro.Data->CurrentAwaitKind, AggValueSlot::ignored(),
308 /*ignoreResult*/false, /*forLValue*/true).LV;
309}
310
311LValue
312CodeGenFunction::EmitCoyieldLValue(const CoyieldExpr *E) {
313 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!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 315, __PRETTY_FUNCTION__))
314 "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!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 315, __PRETTY_FUNCTION__))
315 "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!\""
, "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 315, __PRETTY_FUNCTION__));
316 return emitSuspendExpression(*this, *CurCoro.Data, *E,
317 AwaitKind::Yield, AggValueSlot::ignored(),
318 /*ignoreResult*/false, /*forLValue*/true).LV;
319}
320
321// Hunts for the parameter reference in the parameter copy/move declaration.
322namespace {
323struct GetParamRef : public StmtVisitor<GetParamRef> {
324public:
325 DeclRefExpr *Expr = nullptr;
326 GetParamRef() {}
327 void VisitDeclRefExpr(DeclRefExpr *E) {
328 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\""
, "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 328, __PRETTY_FUNCTION__));
329 Expr = E;
330 }
331 void VisitStmt(Stmt *S) {
332 for (auto *C : S->children()) {
333 if (C)
334 Visit(C);
335 }
336 }
337};
338}
339
340// This class replaces references to parameters to their copies by changing
341// the addresses in CGF.LocalDeclMap and restoring back the original values in
342// its destructor.
343
344namespace {
345 struct ParamReferenceReplacerRAII {
346 CodeGenFunction::DeclMapTy SavedLocals;
347 CodeGenFunction::DeclMapTy& LocalDeclMap;
348
349 ParamReferenceReplacerRAII(CodeGenFunction::DeclMapTy &LocalDeclMap)
350 : LocalDeclMap(LocalDeclMap) {}
351
352 void addCopy(DeclStmt const *PM) {
353 // Figure out what param it refers to.
354
355 assert(PM->isSingleDecl())((PM->isSingleDecl()) ? static_cast<void> (0) : __assert_fail
("PM->isSingleDecl()", "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 355, __PRETTY_FUNCTION__));
356 VarDecl const*VD = static_cast<VarDecl const*>(PM->getSingleDecl());
357 Expr const *InitExpr = VD->getInit();
358 GetParamRef Visitor;
359 Visitor.Visit(const_cast<Expr*>(InitExpr));
360 assert(Visitor.Expr)((Visitor.Expr) ? static_cast<void> (0) : __assert_fail
("Visitor.Expr", "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 360, __PRETTY_FUNCTION__));
361 DeclRefExpr *DREOrig = Visitor.Expr;
362 auto *PD = DREOrig->getDecl();
363
364 auto it = LocalDeclMap.find(PD);
365 assert(it != LocalDeclMap.end() && "parameter is not found")((it != LocalDeclMap.end() && "parameter is not found"
) ? static_cast<void> (0) : __assert_fail ("it != LocalDeclMap.end() && \"parameter is not found\""
, "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 365, __PRETTY_FUNCTION__));
366 SavedLocals.insert({ PD, it->second });
367
368 auto copyIt = LocalDeclMap.find(VD);
369 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\""
, "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 369, __PRETTY_FUNCTION__));
370 it->second = copyIt->getSecond();
371 }
372
373 ~ParamReferenceReplacerRAII() {
374 for (auto&& SavedLocal : SavedLocals) {
375 LocalDeclMap.insert({SavedLocal.first, SavedLocal.second});
376 }
377 }
378 };
379}
380
381// For WinEH exception representation backend needs to know what funclet coro.end
382// belongs to. That information is passed in a funclet bundle.
383static SmallVector<llvm::OperandBundleDef, 1>
384getBundlesForCoroEnd(CodeGenFunction &CGF) {
385 SmallVector<llvm::OperandBundleDef, 1> BundleList;
386
387 if (llvm::Instruction *EHPad = CGF.CurrentFuncletPad)
388 BundleList.emplace_back("funclet", EHPad);
389
390 return BundleList;
391}
392
393namespace {
394// We will insert coro.end to cut any of the destructors for objects that
395// do not need to be destroyed once the coroutine is resumed.
396// See llvm/docs/Coroutines.rst for more details about coro.end.
397struct CallCoroEnd final : public EHScopeStack::Cleanup {
398 void Emit(CodeGenFunction &CGF, Flags flags) override {
399 auto &CGM = CGF.CGM;
400 auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
401 llvm::Function *CoroEndFn = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
402 // See if we have a funclet bundle to associate coro.end with. (WinEH)
403 auto Bundles = getBundlesForCoroEnd(CGF);
404 auto *CoroEnd = CGF.Builder.CreateCall(
405 CoroEndFn, {NullPtr, CGF.Builder.getTrue()}, Bundles);
406 if (Bundles.empty()) {
407 // Otherwise, (landingpad model), create a conditional branch that leads
408 // either to a cleanup block or a block with EH resume instruction.
409 auto *ResumeBB = CGF.getEHResumeBlock(/*cleanup=*/true);
410 auto *CleanupContBB = CGF.createBasicBlock("cleanup.cont");
411 CGF.Builder.CreateCondBr(CoroEnd, ResumeBB, CleanupContBB);
412 CGF.EmitBlock(CleanupContBB);
413 }
414 }
415};
416}
417
418namespace {
419// Make sure to call coro.delete on scope exit.
420struct CallCoroDelete final : public EHScopeStack::Cleanup {
421 Stmt *Deallocate;
422
423 // Emit "if (coro.free(CoroId, CoroBegin)) Deallocate;"
424
425 // Note: That deallocation will be emitted twice: once for a normal exit and
426 // once for exceptional exit. This usage is safe because Deallocate does not
427 // contain any declarations. The SubStmtBuilder::makeNewAndDeleteExpr()
428 // builds a single call to a deallocation function which is safe to emit
429 // multiple times.
430 void Emit(CodeGenFunction &CGF, Flags) override {
431 // Remember the current point, as we are going to emit deallocation code
432 // first to get to coro.free instruction that is an argument to a delete
433 // call.
434 BasicBlock *SaveInsertBlock = CGF.Builder.GetInsertBlock();
435
436 auto *FreeBB = CGF.createBasicBlock("coro.free");
437 CGF.EmitBlock(FreeBB);
438 CGF.EmitStmt(Deallocate);
439
440 auto *AfterFreeBB = CGF.createBasicBlock("after.coro.free");
441 CGF.EmitBlock(AfterFreeBB);
442
443 // We should have captured coro.free from the emission of deallocate.
444 auto *CoroFree = CGF.CurCoro.Data->LastCoroFree;
445 if (!CoroFree) {
446 CGF.CGM.Error(Deallocate->getBeginLoc(),
447 "Deallocation expressoin does not refer to coro.free");
448 return;
449 }
450
451 // Get back to the block we were originally and move coro.free there.
452 auto *InsertPt = SaveInsertBlock->getTerminator();
453 CoroFree->moveBefore(InsertPt);
454 CGF.Builder.SetInsertPoint(InsertPt);
455
456 // Add if (auto *mem = coro.free) Deallocate;
457 auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
458 auto *Cond = CGF.Builder.CreateICmpNE(CoroFree, NullPtr);
459 CGF.Builder.CreateCondBr(Cond, FreeBB, AfterFreeBB);
460
461 // No longer need old terminator.
462 InsertPt->eraseFromParent();
463 CGF.Builder.SetInsertPoint(AfterFreeBB);
464 }
465 explicit CallCoroDelete(Stmt *DeallocStmt) : Deallocate(DeallocStmt) {}
466};
467}
468
469namespace {
470struct GetReturnObjectManager {
471 CodeGenFunction &CGF;
472 CGBuilderTy &Builder;
473 const CoroutineBodyStmt &S;
474
475 Address GroActiveFlag;
476 CodeGenFunction::AutoVarEmission GroEmission;
477
478 GetReturnObjectManager(CodeGenFunction &CGF, const CoroutineBodyStmt &S)
479 : CGF(CGF), Builder(CGF.Builder), S(S), GroActiveFlag(Address::invalid()),
480 GroEmission(CodeGenFunction::AutoVarEmission::invalid()) {}
481
482 // The gro variable has to outlive coroutine frame and coroutine promise, but,
483 // it can only be initialized after coroutine promise was created, thus, we
484 // split its emission in two parts. EmitGroAlloca emits an alloca and sets up
485 // cleanups. Later when coroutine promise is available we initialize the gro
486 // and sets the flag that the cleanup is now active.
487
488 void EmitGroAlloca() {
489 auto *GroDeclStmt = dyn_cast<DeclStmt>(S.getResultDecl());
490 if (!GroDeclStmt) {
491 // If get_return_object returns void, no need to do an alloca.
492 return;
493 }
494
495 auto *GroVarDecl = cast<VarDecl>(GroDeclStmt->getSingleDecl());
496
497 // Set GRO flag that it is not initialized yet
498 GroActiveFlag =
499 CGF.CreateTempAlloca(Builder.getInt1Ty(), CharUnits::One(), "gro.active");
500 Builder.CreateStore(Builder.getFalse(), GroActiveFlag);
501
502 GroEmission = CGF.EmitAutoVarAlloca(*GroVarDecl);
503
504 // Remember the top of EHStack before emitting the cleanup.
505 auto old_top = CGF.EHStack.stable_begin();
506 CGF.EmitAutoVarCleanups(GroEmission);
507 auto top = CGF.EHStack.stable_begin();
508
509 // Make the cleanup conditional on gro.active
510 for (auto b = CGF.EHStack.find(top), e = CGF.EHStack.find(old_top);
511 b != e; b++) {
512 if (auto *Cleanup = dyn_cast<EHCleanupScope>(&*b)) {
513 assert(!Cleanup->hasActiveFlag() && "cleanup already has active flag?")((!Cleanup->hasActiveFlag() && "cleanup already has active flag?"
) ? static_cast<void> (0) : __assert_fail ("!Cleanup->hasActiveFlag() && \"cleanup already has active flag?\""
, "/build/llvm-toolchain-snapshot-9~svn362543/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 513, __PRETTY_FUNCTION__));
514 Cleanup->setActiveFlag(GroActiveFlag);
515 Cleanup->setTestFlagInEHCleanup();
516 Cleanup->setTestFlagInNormalCleanup();
517 }
518 }
519 }
520
521 void EmitGroInit() {
522 if (!GroActiveFlag.isValid()) {
523 // No Gro variable was allocated. Simply emit the call to
524 // get_return_object.
525 CGF.EmitStmt(S.getResultDecl());
526 return;
527 }
528
529 CGF.EmitAutoVarInit(GroEmission);
530 Builder.CreateStore(Builder.getTrue(), GroActiveFlag);
531 }
532};
533}
534
535static void emitBodyAndFallthrough(CodeGenFunction &CGF,
536 const CoroutineBodyStmt &S, Stmt *Body) {
537 CGF.EmitStmt(Body);
538 const bool CanFallthrough = CGF.Builder.GetInsertBlock();
539 if (CanFallthrough)
540 if (Stmt *OnFallthrough = S.getFallthroughHandler())
541 CGF.EmitStmt(OnFallthrough);
542}
543
544void CodeGenFunction::EmitCoroutineBody(const CoroutineBodyStmt &S) {
545 auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
546 auto &TI = CGM.getContext().getTargetInfo();
547 unsigned NewAlign = TI.getNewAlign() / TI.getCharWidth();
548
549 auto *EntryBB = Builder.GetInsertBlock();
550 auto *AllocBB = createBasicBlock("coro.alloc");
551 auto *InitBB = createBasicBlock("coro.init");
552 auto *FinalBB = createBasicBlock("coro.final");
553 auto *RetBB = createBasicBlock("coro.ret");
554
555 auto *CoroId = Builder.CreateCall(
556 CGM.getIntrinsic(llvm::Intrinsic::coro_id),
557 {Builder.getInt32(NewAlign), NullPtr, NullPtr, NullPtr});
558 createCoroData(*this, CurCoro, CoroId);
559 CurCoro.Data->SuspendBB = RetBB;
560
561 // Backend is allowed to elide memory allocations, to help it, emit
562 // auto mem = coro.alloc() ? 0 : ... allocation code ...;
563 auto *CoroAlloc = Builder.CreateCall(
564 CGM.getIntrinsic(llvm::Intrinsic::coro_alloc), {CoroId});
565
566 Builder.CreateCondBr(CoroAlloc, AllocBB, InitBB);
567
568 EmitBlock(AllocBB);
569 auto *AllocateCall = EmitScalarExpr(S.getAllocate());
570 auto *AllocOrInvokeContBB = Builder.GetInsertBlock();
571
572 // Handle allocation failure if 'ReturnStmtOnAllocFailure' was provided.
573 if (auto *RetOnAllocFailure = S.getReturnStmtOnAllocFailure()) {
574 auto *RetOnFailureBB = createBasicBlock("coro.ret.on.failure");
575
576 // See if allocation was successful.
577 auto *NullPtr = llvm::ConstantPointerNull::get(Int8PtrTy);
578 auto *Cond = Builder.CreateICmpNE(AllocateCall, NullPtr);
579 Builder.CreateCondBr(Cond, InitBB, RetOnFailureBB);
580
581 // If not, return OnAllocFailure object.
582 EmitBlock(RetOnFailureBB);
583 EmitStmt(RetOnAllocFailure);
584 }
585 else {
586 Builder.CreateBr(InitBB);
587 }
588
589 EmitBlock(InitBB);
590
591 // Pass the result of the allocation to coro.begin.
592 auto *Phi = Builder.CreatePHI(VoidPtrTy, 2);
593 Phi->addIncoming(NullPtr, EntryBB);
594 Phi->addIncoming(AllocateCall, AllocOrInvokeContBB);
595 auto *CoroBegin = Builder.CreateCall(
596 CGM.getIntrinsic(llvm::Intrinsic::coro_begin), {CoroId, Phi});
597 CurCoro.Data->CoroBegin = CoroBegin;
598
599 GetReturnObjectManager GroManager(*this, S);
600 GroManager.EmitGroAlloca();
601
602 CurCoro.Data->CleanupJD = getJumpDestInCurrentScope(RetBB);
603 {
604 ParamReferenceReplacerRAII ParamReplacer(LocalDeclMap);
605 CodeGenFunction::RunCleanupsScope ResumeScope(*this);
606 EHStack.pushCleanup<CallCoroDelete>(NormalAndEHCleanup, S.getDeallocate());
607
608 // Create parameter copies. We do it before creating a promise, since an
609 // evolution of coroutine TS may allow promise constructor to observe
610 // parameter copies.
611 for (auto *PM : S.getParamMoves()) {
612 EmitStmt(PM);
613 ParamReplacer.addCopy(cast<DeclStmt>(PM));
614 // TODO: if(CoroParam(...)) need to surround ctor and dtor
615 // for the copy, so that llvm can elide it if the copy is
616 // not needed.
617 }
618
619 EmitStmt(S.getPromiseDeclStmt());
620
621 Address PromiseAddr = GetAddrOfLocalVar(S.getPromiseDecl());
622 auto *PromiseAddrVoidPtr =
623 new llvm::BitCastInst(PromiseAddr.getPointer(), VoidPtrTy, "", CoroId);
624 // Update CoroId to refer to the promise. We could not do it earlier because
625 // promise local variable was not emitted yet.
626 CoroId->setArgOperand(1, PromiseAddrVoidPtr);
627
628 // Now we have the promise, initialize the GRO
629 GroManager.EmitGroInit();
630
631 EHStack.pushCleanup<CallCoroEnd>(EHCleanup);
632
633 CurCoro.Data->CurrentAwaitKind = AwaitKind::Init;
634 CurCoro.Data->ExceptionHandler = S.getExceptionHandler();
635 EmitStmt(S.getInitSuspendStmt());
636 CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
637
638 CurCoro.Data->CurrentAwaitKind = AwaitKind::Normal;
639
640 if (CurCoro.Data->ExceptionHandler) {
641 // If we generated IR to record whether an exception was thrown from
642 // 'await_resume', then use that IR to determine whether the coroutine
643 // body should be skipped.
644 // If we didn't generate the IR (perhaps because 'await_resume' was marked
645 // as 'noexcept'), then we skip this check.
646 BasicBlock *ContBB = nullptr;
647 if (CurCoro.Data->ResumeEHVar) {
648 BasicBlock *BodyBB = createBasicBlock("coro.resumed.body");
649 ContBB = createBasicBlock("coro.resumed.cont");
650 Value *SkipBody = Builder.CreateFlagLoad(CurCoro.Data->ResumeEHVar,
651 "coro.resumed.eh");
652 Builder.CreateCondBr(SkipBody, ContBB, BodyBB);
653 EmitBlock(BodyBB);
654 }
655
656 auto Loc = S.getBeginLoc();
657 CXXCatchStmt Catch(Loc, /*exDecl=*/nullptr,
658 CurCoro.Data->ExceptionHandler);
659 auto *TryStmt =
660 CXXTryStmt::Create(getContext(), Loc, S.getBody(), &Catch);
661
662 EnterCXXTryStmt(*TryStmt);
663 emitBodyAndFallthrough(*this, S, TryStmt->getTryBlock());
664 ExitCXXTryStmt(*TryStmt);
665
666 if (ContBB)
667 EmitBlock(ContBB);
668 }
669 else {
670 emitBodyAndFallthrough(*this, S, S.getBody());
671 }
672
673 // See if we need to generate final suspend.
674 const bool CanFallthrough = Builder.GetInsertBlock();
675 const bool HasCoreturns = CurCoro.Data->CoreturnCount > 0;
676 if (CanFallthrough || HasCoreturns) {
677 EmitBlock(FinalBB);
678 CurCoro.Data->CurrentAwaitKind = AwaitKind::Final;
679 EmitStmt(S.getFinalSuspendStmt());
680 } else {
681 // We don't need FinalBB. Emit it to make sure the block is deleted.
682 EmitBlock(FinalBB, /*IsFinished=*/true);
683 }
684 }
685
686 EmitBlock(RetBB);
687 // Emit coro.end before getReturnStmt (and parameter destructors), since
688 // resume and destroy parts of the coroutine should not include them.
689 llvm::Function *CoroEnd = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
690 Builder.CreateCall(CoroEnd, {NullPtr, Builder.getFalse()});
691
692 if (Stmt *Ret = S.getReturnStmt())
693 EmitStmt(Ret);
694}
695
696// Emit coroutine intrinsic and patch up arguments of the token type.
697RValue CodeGenFunction::EmitCoroutineIntrinsic(const CallExpr *E,
698 unsigned int IID) {
699 SmallVector<llvm::Value *, 8> Args;
700 switch (IID) {
701 default:
702 break;
703 // The coro.frame builtin is replaced with an SSA value of the coro.begin
704 // intrinsic.
705 case llvm::Intrinsic::coro_frame: {
706 if (CurCoro.Data && CurCoro.Data->CoroBegin) {
707 return RValue::get(CurCoro.Data->CoroBegin);
708 }
709 CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_begin "
710 "has been used earlier in this function");
711 auto NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
712 return RValue::get(NullPtr);
713 }
714 // The following three intrinsics take a token parameter referring to a token
715 // returned by earlier call to @llvm.coro.id. Since we cannot represent it in
716 // builtins, we patch it up here.
717 case llvm::Intrinsic::coro_alloc:
718 case llvm::Intrinsic::coro_begin:
719 case llvm::Intrinsic::coro_free: {
720 if (CurCoro.Data && CurCoro.Data->CoroId) {
721 Args.push_back(CurCoro.Data->CoroId);
722 break;
723 }
724 CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_id has"
725 " been used earlier in this function");
726 // Fallthrough to the next case to add TokenNone as the first argument.
727 LLVM_FALLTHROUGH[[clang::fallthrough]];
728 }
729 // @llvm.coro.suspend takes a token parameter. Add token 'none' as the first
730 // argument.
731 case llvm::Intrinsic::coro_suspend:
732 Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
733 break;
734 }
735 for (const Expr *Arg : E->arguments())
736 Args.push_back(EmitScalarExpr(Arg));
737
738 llvm::Function *F = CGM.getIntrinsic(IID);
739 llvm::CallInst *Call = Builder.CreateCall(F, Args);
740
741 // Note: The following code is to enable to emit coro.id and coro.begin by
742 // hand to experiment with coroutines in C.
743 // If we see @llvm.coro.id remember it in the CoroData. We will update
744 // coro.alloc, coro.begin and coro.free intrinsics to refer to it.
745 if (IID == llvm::Intrinsic::coro_id) {
746 createCoroData(*this, CurCoro, Call, E);
747 }
748 else if (IID == llvm::Intrinsic::coro_begin) {
749 if (CurCoro.Data)
750 CurCoro.Data->CoroBegin = Call;
751 }
752 else if (IID == llvm::Intrinsic::coro_free) {
753 // Remember the last coro_free as we need it to build the conditional
754 // deletion of the coroutine frame.
755 if (CurCoro.Data)
756 CurCoro.Data->LastCoroFree = Call;
757 }
758 return RValue::get(Call);
759}