Bug Summary

File:tools/clang/lib/CodeGen/CGCoroutine.cpp
Warning:line 208, column 5
Value stored to 'SuspendBlock' is never read

Annotated Source Code

Press '?' to see keyboard shortcuts

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 -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-8/lib/clang/8.0.0 -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/tools/clang/lib/CodeGen -I /build/llvm-toolchain-snapshot-8~svn345461/tools/clang/lib/CodeGen -I /build/llvm-toolchain-snapshot-8~svn345461/tools/clang/include -I /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-8~svn345461/build-llvm/include -I /build/llvm-toolchain-snapshot-8~svn345461/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/8.0.0/include/ -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-8/lib/clang/8.0.0/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-8~svn345461/build-llvm/tools/clang/lib/CodeGen -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -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-2018-10-27-211344-32123-1 -x c++ /build/llvm-toolchain-snapshot-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp -faddrsig
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 // The promise type's 'unhandled_exception' handler, if it defines one.
48 Stmt *ExceptionHandler = nullptr;
49
50 // A temporary i1 alloca that stores whether 'await_resume' threw an
51 // exception. If it did, 'true' is stored in this variable, and the coroutine
52 // body must be skipped. If the promise type does not define an exception
53 // handler, this is null.
54 llvm::Value *ResumeEHVar = nullptr;
55
56 // Stores the jump destination just before the coroutine memory is freed.
57 // This is the destination that every suspend point jumps to for the cleanup
58 // branch.
59 CodeGenFunction::JumpDest CleanupJD;
60
61 // Stores the jump destination just before the final suspend. The co_return
62 // statements jumps to this point after calling return_xxx promise member.
63 CodeGenFunction::JumpDest FinalJD;
64
65 // Stores the llvm.coro.id emitted in the function so that we can supply it
66 // as the first argument to coro.begin, coro.alloc and coro.free intrinsics.
67 // Note: llvm.coro.id returns a token that cannot be directly expressed in a
68 // builtin.
69 llvm::CallInst *CoroId = nullptr;
70
71 // Stores the llvm.coro.begin emitted in the function so that we can replace
72 // all coro.frame intrinsics with direct SSA value of coro.begin that returns
73 // the address of the coroutine frame of the current coroutine.
74 llvm::CallInst *CoroBegin = nullptr;
75
76 // Stores the last emitted coro.free for the deallocate expressions, we use it
77 // to wrap dealloc code with if(auto mem = coro.free) dealloc(mem).
78 llvm::CallInst *LastCoroFree = nullptr;
79
80 // If coro.id came from the builtin, remember the expression to give better
81 // diagnostic. If CoroIdExpr is nullptr, the coro.id was created by
82 // EmitCoroutineBody.
83 CallExpr const *CoroIdExpr = nullptr;
84};
85
86// Defining these here allows to keep CGCoroData private to this file.
87clang::CodeGen::CodeGenFunction::CGCoroInfo::CGCoroInfo() {}
88CodeGenFunction::CGCoroInfo::~CGCoroInfo() {}
89
90static void createCoroData(CodeGenFunction &CGF,
91 CodeGenFunction::CGCoroInfo &CurCoro,
92 llvm::CallInst *CoroId,
93 CallExpr const *CoroIdExpr = nullptr) {
94 if (CurCoro.Data) {
95 if (CurCoro.Data->CoroIdExpr)
96 CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
97 "only one __builtin_coro_id can be used in a function");
98 else if (CoroIdExpr)
99 CGF.CGM.Error(CoroIdExpr->getBeginLoc(),
100 "__builtin_coro_id shall not be used in a C++ coroutine");
101 else
102 llvm_unreachable("EmitCoroutineBodyStatement called twice?")::llvm::llvm_unreachable_internal("EmitCoroutineBodyStatement called twice?"
, "/build/llvm-toolchain-snapshot-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 102)
;
103
104 return;
105 }
106
107 CurCoro.Data = std::unique_ptr<CGCoroData>(new CGCoroData);
108 CurCoro.Data->CoroId = CoroId;
109 CurCoro.Data->CoroIdExpr = CoroIdExpr;
110}
111
112// Synthesize a pretty name for a suspend point.
113static SmallString<32> buildSuspendPrefixStr(CGCoroData &Coro, AwaitKind Kind) {
114 unsigned No = 0;
115 switch (Kind) {
116 case AwaitKind::Init:
117 case AwaitKind::Final:
118 break;
119 case AwaitKind::Normal:
120 No = ++Coro.AwaitNum;
121 break;
122 case AwaitKind::Yield:
123 No = ++Coro.YieldNum;
124 break;
125 }
126 SmallString<32> Prefix(AwaitKindStr[static_cast<unsigned>(Kind)]);
127 if (No > 1) {
128 Twine(No).toVector(Prefix);
129 }
130 return Prefix;
131}
132
133static bool memberCallExpressionCanThrow(const Expr *E) {
134 if (const auto *CE = dyn_cast<CXXMemberCallExpr>(E))
135 if (const auto *Proto =
136 CE->getMethodDecl()->getType()->getAs<FunctionProtoType>())
137 if (isNoexceptExceptionSpec(Proto->getExceptionSpecType()) &&
138 Proto->canThrow() == CT_Cannot)
139 return false;
140 return true;
141}
142
143// Emit suspend expression which roughly looks like:
144//
145// auto && x = CommonExpr();
146// if (!x.await_ready()) {
147// llvm_coro_save();
148// x.await_suspend(...); (*)
149// llvm_coro_suspend(); (**)
150// }
151// x.await_resume();
152//
153// where the result of the entire expression is the result of x.await_resume()
154//
155// (*) If x.await_suspend return type is bool, it allows to veto a suspend:
156// if (x.await_suspend(...))
157// llvm_coro_suspend();
158//
159// (**) llvm_coro_suspend() encodes three possible continuations as
160// a switch instruction:
161//
162// %where-to = call i8 @llvm.coro.suspend(...)
163// switch i8 %where-to, label %coro.ret [ ; jump to epilogue to suspend
164// i8 0, label %yield.ready ; go here when resumed
165// i8 1, label %yield.cleanup ; go here when destroyed
166// ]
167//
168// See llvm's docs/Coroutines.rst for more details.
169//
170namespace {
171 struct LValueOrRValue {
172 LValue LV;
173 RValue RV;
174 };
175}
176static LValueOrRValue emitSuspendExpression(CodeGenFunction &CGF, CGCoroData &Coro,
177 CoroutineSuspendExpr const &S,
178 AwaitKind Kind, AggValueSlot aggSlot,
179 bool ignoreResult, bool forLValue) {
180 auto *E = S.getCommonExpr();
181
182 auto Binder =
183 CodeGenFunction::OpaqueValueMappingData::bind(CGF, S.getOpaqueValue(), E);
184 auto UnbindOnExit = llvm::make_scope_exit([&] { Binder.unbind(CGF); });
185
186 auto Prefix = buildSuspendPrefixStr(Coro, Kind);
187 BasicBlock *ReadyBlock = CGF.createBasicBlock(Prefix + Twine(".ready"));
188 BasicBlock *SuspendBlock = CGF.createBasicBlock(Prefix + Twine(".suspend"));
189 BasicBlock *CleanupBlock = CGF.createBasicBlock(Prefix + Twine(".cleanup"));
190
191 // If expression is ready, no need to suspend.
192 CGF.EmitBranchOnBoolExpr(S.getReadyExpr(), ReadyBlock, SuspendBlock, 0);
193
194 // Otherwise, emit suspend logic.
195 CGF.EmitBlock(SuspendBlock);
196
197 auto &Builder = CGF.Builder;
198 llvm::Function *CoroSave = CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_save);
199 auto *NullPtr = llvm::ConstantPointerNull::get(CGF.CGM.Int8PtrTy);
200 auto *SaveCall = Builder.CreateCall(CoroSave, {NullPtr});
201
202 auto *SuspendRet = CGF.EmitScalarExpr(S.getSuspendExpr());
203 if (SuspendRet != nullptr && SuspendRet->getType()->isIntegerTy(1)) {
204 // Veto suspension if requested by bool returning await_suspend.
205 BasicBlock *RealSuspendBlock =
206 CGF.createBasicBlock(Prefix + Twine(".suspend.bool"));
207 CGF.Builder.CreateCondBr(SuspendRet, RealSuspendBlock, ReadyBlock);
208 SuspendBlock = RealSuspendBlock;
Value stored to 'SuspendBlock' is never read
209 CGF.EmitBlock(RealSuspendBlock);
210 }
211
212 // Emit the suspend point.
213 const bool IsFinalSuspend = (Kind == AwaitKind::Final);
214 llvm::Function *CoroSuspend =
215 CGF.CGM.getIntrinsic(llvm::Intrinsic::coro_suspend);
216 auto *SuspendResult = Builder.CreateCall(
217 CoroSuspend, {SaveCall, Builder.getInt1(IsFinalSuspend)});
218
219 // Create a switch capturing three possible continuations.
220 auto *Switch = Builder.CreateSwitch(SuspendResult, Coro.SuspendBB, 2);
221 Switch->addCase(Builder.getInt8(0), ReadyBlock);
222 Switch->addCase(Builder.getInt8(1), CleanupBlock);
223
224 // Emit cleanup for this suspend point.
225 CGF.EmitBlock(CleanupBlock);
226 CGF.EmitBranchThroughCleanup(Coro.CleanupJD);
227
228 // Emit await_resume expression.
229 CGF.EmitBlock(ReadyBlock);
230
231 // Exception handling requires additional IR. If the 'await_resume' function
232 // is marked as 'noexcept', we avoid generating this additional IR.
233 CXXTryStmt *TryStmt = nullptr;
234 if (Coro.ExceptionHandler && Kind == AwaitKind::Init &&
235 memberCallExpressionCanThrow(S.getResumeExpr())) {
236 Coro.ResumeEHVar =
237 CGF.CreateTempAlloca(Builder.getInt1Ty(), Prefix + Twine("resume.eh"));
238 Builder.CreateFlagStore(true, Coro.ResumeEHVar);
239
240 auto Loc = S.getResumeExpr()->getExprLoc();
241 auto *Catch = new (CGF.getContext())
242 CXXCatchStmt(Loc, /*exDecl=*/nullptr, Coro.ExceptionHandler);
243 auto *TryBody =
244 CompoundStmt::Create(CGF.getContext(), S.getResumeExpr(), Loc, Loc);
245 TryStmt = CXXTryStmt::Create(CGF.getContext(), Loc, TryBody, Catch);
246 CGF.EnterCXXTryStmt(*TryStmt);
247 }
248
249 LValueOrRValue Res;
250 if (forLValue)
251 Res.LV = CGF.EmitLValue(S.getResumeExpr());
252 else
253 Res.RV = CGF.EmitAnyExpr(S.getResumeExpr(), aggSlot, ignoreResult);
254
255 if (TryStmt) {
256 Builder.CreateFlagStore(false, Coro.ResumeEHVar);
257 CGF.ExitCXXTryStmt(*TryStmt);
258 }
259
260 return Res;
261}
262
263RValue CodeGenFunction::EmitCoawaitExpr(const CoawaitExpr &E,
264 AggValueSlot aggSlot,
265 bool ignoreResult) {
266 return emitSuspendExpression(*this, *CurCoro.Data, E,
267 CurCoro.Data->CurrentAwaitKind, aggSlot,
268 ignoreResult, /*forLValue*/false).RV;
269}
270RValue CodeGenFunction::EmitCoyieldExpr(const CoyieldExpr &E,
271 AggValueSlot aggSlot,
272 bool ignoreResult) {
273 return emitSuspendExpression(*this, *CurCoro.Data, E, AwaitKind::Yield,
274 aggSlot, ignoreResult, /*forLValue*/false).RV;
275}
276
277void CodeGenFunction::EmitCoreturnStmt(CoreturnStmt const &S) {
278 ++CurCoro.Data->CoreturnCount;
279 const Expr *RV = S.getOperand();
280 if (RV && RV->getType()->isVoidType()) {
281 // Make sure to evaluate the expression of a co_return with a void
282 // expression for side effects.
283 RunCleanupsScope cleanupScope(*this);
284 EmitIgnoredExpr(RV);
285 }
286 EmitStmt(S.getPromiseCall());
287 EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
288}
289
290
291#ifndef NDEBUG
292static QualType getCoroutineSuspendExprReturnType(const ASTContext &Ctx,
293 const CoroutineSuspendExpr *E) {
294 const auto *RE = E->getResumeExpr();
295 // Is it possible for RE to be a CXXBindTemporaryExpr wrapping
296 // a MemberCallExpr?
297 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-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 297, __PRETTY_FUNCTION__))
;
298 return cast<CallExpr>(RE)->getCallReturnType(Ctx);
299}
300#endif
301
302LValue
303CodeGenFunction::EmitCoawaitLValue(const CoawaitExpr *E) {
304 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-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 306, __PRETTY_FUNCTION__))
305 "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-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 306, __PRETTY_FUNCTION__))
306 "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-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 306, __PRETTY_FUNCTION__))
;
307 return emitSuspendExpression(*this, *CurCoro.Data, *E,
308 CurCoro.Data->CurrentAwaitKind, AggValueSlot::ignored(),
309 /*ignoreResult*/false, /*forLValue*/true).LV;
310}
311
312LValue
313CodeGenFunction::EmitCoyieldLValue(const CoyieldExpr *E) {
314 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-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 316, __PRETTY_FUNCTION__))
315 "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-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 316, __PRETTY_FUNCTION__))
316 "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-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 316, __PRETTY_FUNCTION__))
;
317 return emitSuspendExpression(*this, *CurCoro.Data, *E,
318 AwaitKind::Yield, AggValueSlot::ignored(),
319 /*ignoreResult*/false, /*forLValue*/true).LV;
320}
321
322// Hunts for the parameter reference in the parameter copy/move declaration.
323namespace {
324struct GetParamRef : public StmtVisitor<GetParamRef> {
325public:
326 DeclRefExpr *Expr = nullptr;
327 GetParamRef() {}
328 void VisitDeclRefExpr(DeclRefExpr *E) {
329 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-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 329, __PRETTY_FUNCTION__))
;
330 Expr = E;
331 }
332 void VisitStmt(Stmt *S) {
333 for (auto *C : S->children()) {
334 if (C)
335 Visit(C);
336 }
337 }
338};
339}
340
341// This class replaces references to parameters to their copies by changing
342// the addresses in CGF.LocalDeclMap and restoring back the original values in
343// its destructor.
344
345namespace {
346 struct ParamReferenceReplacerRAII {
347 CodeGenFunction::DeclMapTy SavedLocals;
348 CodeGenFunction::DeclMapTy& LocalDeclMap;
349
350 ParamReferenceReplacerRAII(CodeGenFunction::DeclMapTy &LocalDeclMap)
351 : LocalDeclMap(LocalDeclMap) {}
352
353 void addCopy(DeclStmt const *PM) {
354 // Figure out what param it refers to.
355
356 assert(PM->isSingleDecl())((PM->isSingleDecl()) ? static_cast<void> (0) : __assert_fail
("PM->isSingleDecl()", "/build/llvm-toolchain-snapshot-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 356, __PRETTY_FUNCTION__))
;
357 VarDecl const*VD = static_cast<VarDecl const*>(PM->getSingleDecl());
358 Expr const *InitExpr = VD->getInit();
359 GetParamRef Visitor;
360 Visitor.Visit(const_cast<Expr*>(InitExpr));
361 assert(Visitor.Expr)((Visitor.Expr) ? static_cast<void> (0) : __assert_fail
("Visitor.Expr", "/build/llvm-toolchain-snapshot-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 361, __PRETTY_FUNCTION__))
;
362 DeclRefExpr *DREOrig = Visitor.Expr;
363 auto *PD = DREOrig->getDecl();
364
365 auto it = LocalDeclMap.find(PD);
366 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-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 366, __PRETTY_FUNCTION__))
;
367 SavedLocals.insert({ PD, it->second });
368
369 auto copyIt = LocalDeclMap.find(VD);
370 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-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 370, __PRETTY_FUNCTION__))
;
371 it->second = copyIt->getSecond();
372 }
373
374 ~ParamReferenceReplacerRAII() {
375 for (auto&& SavedLocal : SavedLocals) {
376 LocalDeclMap.insert({SavedLocal.first, SavedLocal.second});
377 }
378 }
379 };
380}
381
382// For WinEH exception representation backend needs to know what funclet coro.end
383// belongs to. That information is passed in a funclet bundle.
384static SmallVector<llvm::OperandBundleDef, 1>
385getBundlesForCoroEnd(CodeGenFunction &CGF) {
386 SmallVector<llvm::OperandBundleDef, 1> BundleList;
387
388 if (llvm::Instruction *EHPad = CGF.CurrentFuncletPad)
389 BundleList.emplace_back("funclet", EHPad);
390
391 return BundleList;
392}
393
394namespace {
395// We will insert coro.end to cut any of the destructors for objects that
396// do not need to be destroyed once the coroutine is resumed.
397// See llvm/docs/Coroutines.rst for more details about coro.end.
398struct CallCoroEnd final : public EHScopeStack::Cleanup {
399 void Emit(CodeGenFunction &CGF, Flags flags) override {
400 auto &CGM = CGF.CGM;
401 auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
402 llvm::Function *CoroEndFn = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
403 // See if we have a funclet bundle to associate coro.end with. (WinEH)
404 auto Bundles = getBundlesForCoroEnd(CGF);
405 auto *CoroEnd = CGF.Builder.CreateCall(
406 CoroEndFn, {NullPtr, CGF.Builder.getTrue()}, Bundles);
407 if (Bundles.empty()) {
408 // Otherwise, (landingpad model), create a conditional branch that leads
409 // either to a cleanup block or a block with EH resume instruction.
410 auto *ResumeBB = CGF.getEHResumeBlock(/*cleanup=*/true);
411 auto *CleanupContBB = CGF.createBasicBlock("cleanup.cont");
412 CGF.Builder.CreateCondBr(CoroEnd, ResumeBB, CleanupContBB);
413 CGF.EmitBlock(CleanupContBB);
414 }
415 }
416};
417}
418
419namespace {
420// Make sure to call coro.delete on scope exit.
421struct CallCoroDelete final : public EHScopeStack::Cleanup {
422 Stmt *Deallocate;
423
424 // Emit "if (coro.free(CoroId, CoroBegin)) Deallocate;"
425
426 // Note: That deallocation will be emitted twice: once for a normal exit and
427 // once for exceptional exit. This usage is safe because Deallocate does not
428 // contain any declarations. The SubStmtBuilder::makeNewAndDeleteExpr()
429 // builds a single call to a deallocation function which is safe to emit
430 // multiple times.
431 void Emit(CodeGenFunction &CGF, Flags) override {
432 // Remember the current point, as we are going to emit deallocation code
433 // first to get to coro.free instruction that is an argument to a delete
434 // call.
435 BasicBlock *SaveInsertBlock = CGF.Builder.GetInsertBlock();
436
437 auto *FreeBB = CGF.createBasicBlock("coro.free");
438 CGF.EmitBlock(FreeBB);
439 CGF.EmitStmt(Deallocate);
440
441 auto *AfterFreeBB = CGF.createBasicBlock("after.coro.free");
442 CGF.EmitBlock(AfterFreeBB);
443
444 // We should have captured coro.free from the emission of deallocate.
445 auto *CoroFree = CGF.CurCoro.Data->LastCoroFree;
446 if (!CoroFree) {
447 CGF.CGM.Error(Deallocate->getBeginLoc(),
448 "Deallocation expressoin does not refer to coro.free");
449 return;
450 }
451
452 // Get back to the block we were originally and move coro.free there.
453 auto *InsertPt = SaveInsertBlock->getTerminator();
454 CoroFree->moveBefore(InsertPt);
455 CGF.Builder.SetInsertPoint(InsertPt);
456
457 // Add if (auto *mem = coro.free) Deallocate;
458 auto *NullPtr = llvm::ConstantPointerNull::get(CGF.Int8PtrTy);
459 auto *Cond = CGF.Builder.CreateICmpNE(CoroFree, NullPtr);
460 CGF.Builder.CreateCondBr(Cond, FreeBB, AfterFreeBB);
461
462 // No longer need old terminator.
463 InsertPt->eraseFromParent();
464 CGF.Builder.SetInsertPoint(AfterFreeBB);
465 }
466 explicit CallCoroDelete(Stmt *DeallocStmt) : Deallocate(DeallocStmt) {}
467};
468}
469
470namespace {
471struct GetReturnObjectManager {
472 CodeGenFunction &CGF;
473 CGBuilderTy &Builder;
474 const CoroutineBodyStmt &S;
475
476 Address GroActiveFlag;
477 CodeGenFunction::AutoVarEmission GroEmission;
478
479 GetReturnObjectManager(CodeGenFunction &CGF, const CoroutineBodyStmt &S)
480 : CGF(CGF), Builder(CGF.Builder), S(S), GroActiveFlag(Address::invalid()),
481 GroEmission(CodeGenFunction::AutoVarEmission::invalid()) {}
482
483 // The gro variable has to outlive coroutine frame and coroutine promise, but,
484 // it can only be initialized after coroutine promise was created, thus, we
485 // split its emission in two parts. EmitGroAlloca emits an alloca and sets up
486 // cleanups. Later when coroutine promise is available we initialize the gro
487 // and sets the flag that the cleanup is now active.
488
489 void EmitGroAlloca() {
490 auto *GroDeclStmt = dyn_cast<DeclStmt>(S.getResultDecl());
491 if (!GroDeclStmt) {
492 // If get_return_object returns void, no need to do an alloca.
493 return;
494 }
495
496 auto *GroVarDecl = cast<VarDecl>(GroDeclStmt->getSingleDecl());
497
498 // Set GRO flag that it is not initialized yet
499 GroActiveFlag =
500 CGF.CreateTempAlloca(Builder.getInt1Ty(), CharUnits::One(), "gro.active");
501 Builder.CreateStore(Builder.getFalse(), GroActiveFlag);
502
503 GroEmission = CGF.EmitAutoVarAlloca(*GroVarDecl);
504
505 // Remember the top of EHStack before emitting the cleanup.
506 auto old_top = CGF.EHStack.stable_begin();
507 CGF.EmitAutoVarCleanups(GroEmission);
508 auto top = CGF.EHStack.stable_begin();
509
510 // Make the cleanup conditional on gro.active
511 for (auto b = CGF.EHStack.find(top), e = CGF.EHStack.find(old_top);
512 b != e; b++) {
513 if (auto *Cleanup = dyn_cast<EHCleanupScope>(&*b)) {
514 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-8~svn345461/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 514, __PRETTY_FUNCTION__))
;
515 Cleanup->setActiveFlag(GroActiveFlag);
516 Cleanup->setTestFlagInEHCleanup();
517 Cleanup->setTestFlagInNormalCleanup();
518 }
519 }
520 }
521
522 void EmitGroInit() {
523 if (!GroActiveFlag.isValid()) {
524 // No Gro variable was allocated. Simply emit the call to
525 // get_return_object.
526 CGF.EmitStmt(S.getResultDecl());
527 return;
528 }
529
530 CGF.EmitAutoVarInit(GroEmission);
531 Builder.CreateStore(Builder.getTrue(), GroActiveFlag);
532 }
533};
534}
535
536static void emitBodyAndFallthrough(CodeGenFunction &CGF,
537 const CoroutineBodyStmt &S, Stmt *Body) {
538 CGF.EmitStmt(Body);
539 const bool CanFallthrough = CGF.Builder.GetInsertBlock();
540 if (CanFallthrough)
541 if (Stmt *OnFallthrough = S.getFallthroughHandler())
542 CGF.EmitStmt(OnFallthrough);
543}
544
545void CodeGenFunction::EmitCoroutineBody(const CoroutineBodyStmt &S) {
546 auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
547 auto &TI = CGM.getContext().getTargetInfo();
548 unsigned NewAlign = TI.getNewAlign() / TI.getCharWidth();
549
550 auto *EntryBB = Builder.GetInsertBlock();
551 auto *AllocBB = createBasicBlock("coro.alloc");
552 auto *InitBB = createBasicBlock("coro.init");
553 auto *FinalBB = createBasicBlock("coro.final");
554 auto *RetBB = createBasicBlock("coro.ret");
555
556 auto *CoroId = Builder.CreateCall(
557 CGM.getIntrinsic(llvm::Intrinsic::coro_id),
558 {Builder.getInt32(NewAlign), NullPtr, NullPtr, NullPtr});
559 createCoroData(*this, CurCoro, CoroId);
560 CurCoro.Data->SuspendBB = RetBB;
561
562 // Backend is allowed to elide memory allocations, to help it, emit
563 // auto mem = coro.alloc() ? 0 : ... allocation code ...;
564 auto *CoroAlloc = Builder.CreateCall(
565 CGM.getIntrinsic(llvm::Intrinsic::coro_alloc), {CoroId});
566
567 Builder.CreateCondBr(CoroAlloc, AllocBB, InitBB);
568
569 EmitBlock(AllocBB);
570 auto *AllocateCall = EmitScalarExpr(S.getAllocate());
571 auto *AllocOrInvokeContBB = Builder.GetInsertBlock();
572
573 // Handle allocation failure if 'ReturnStmtOnAllocFailure' was provided.
574 if (auto *RetOnAllocFailure = S.getReturnStmtOnAllocFailure()) {
575 auto *RetOnFailureBB = createBasicBlock("coro.ret.on.failure");
576
577 // See if allocation was successful.
578 auto *NullPtr = llvm::ConstantPointerNull::get(Int8PtrTy);
579 auto *Cond = Builder.CreateICmpNE(AllocateCall, NullPtr);
580 Builder.CreateCondBr(Cond, InitBB, RetOnFailureBB);
581
582 // If not, return OnAllocFailure object.
583 EmitBlock(RetOnFailureBB);
584 EmitStmt(RetOnAllocFailure);
585 }
586 else {
587 Builder.CreateBr(InitBB);
588 }
589
590 EmitBlock(InitBB);
591
592 // Pass the result of the allocation to coro.begin.
593 auto *Phi = Builder.CreatePHI(VoidPtrTy, 2);
594 Phi->addIncoming(NullPtr, EntryBB);
595 Phi->addIncoming(AllocateCall, AllocOrInvokeContBB);
596 auto *CoroBegin = Builder.CreateCall(
597 CGM.getIntrinsic(llvm::Intrinsic::coro_begin), {CoroId, Phi});
598 CurCoro.Data->CoroBegin = CoroBegin;
599
600 GetReturnObjectManager GroManager(*this, S);
601 GroManager.EmitGroAlloca();
602
603 CurCoro.Data->CleanupJD = getJumpDestInCurrentScope(RetBB);
604 {
605 ParamReferenceReplacerRAII ParamReplacer(LocalDeclMap);
606 CodeGenFunction::RunCleanupsScope ResumeScope(*this);
607 EHStack.pushCleanup<CallCoroDelete>(NormalAndEHCleanup, S.getDeallocate());
608
609 // Create parameter copies. We do it before creating a promise, since an
610 // evolution of coroutine TS may allow promise constructor to observe
611 // parameter copies.
612 for (auto *PM : S.getParamMoves()) {
613 EmitStmt(PM);
614 ParamReplacer.addCopy(cast<DeclStmt>(PM));
615 // TODO: if(CoroParam(...)) need to surround ctor and dtor
616 // for the copy, so that llvm can elide it if the copy is
617 // not needed.
618 }
619
620 EmitStmt(S.getPromiseDeclStmt());
621
622 Address PromiseAddr = GetAddrOfLocalVar(S.getPromiseDecl());
623 auto *PromiseAddrVoidPtr =
624 new llvm::BitCastInst(PromiseAddr.getPointer(), VoidPtrTy, "", CoroId);
625 // Update CoroId to refer to the promise. We could not do it earlier because
626 // promise local variable was not emitted yet.
627 CoroId->setArgOperand(1, PromiseAddrVoidPtr);
628
629 // Now we have the promise, initialize the GRO
630 GroManager.EmitGroInit();
631
632 EHStack.pushCleanup<CallCoroEnd>(EHCleanup);
633
634 CurCoro.Data->CurrentAwaitKind = AwaitKind::Init;
635 CurCoro.Data->ExceptionHandler = S.getExceptionHandler();
636 EmitStmt(S.getInitSuspendStmt());
637 CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
638
639 CurCoro.Data->CurrentAwaitKind = AwaitKind::Normal;
640
641 if (CurCoro.Data->ExceptionHandler) {
642 // If we generated IR to record whether an exception was thrown from
643 // 'await_resume', then use that IR to determine whether the coroutine
644 // body should be skipped.
645 // If we didn't generate the IR (perhaps because 'await_resume' was marked
646 // as 'noexcept'), then we skip this check.
647 BasicBlock *ContBB = nullptr;
648 if (CurCoro.Data->ResumeEHVar) {
649 BasicBlock *BodyBB = createBasicBlock("coro.resumed.body");
650 ContBB = createBasicBlock("coro.resumed.cont");
651 Value *SkipBody = Builder.CreateFlagLoad(CurCoro.Data->ResumeEHVar,
652 "coro.resumed.eh");
653 Builder.CreateCondBr(SkipBody, ContBB, BodyBB);
654 EmitBlock(BodyBB);
655 }
656
657 auto Loc = S.getBeginLoc();
658 CXXCatchStmt Catch(Loc, /*exDecl=*/nullptr,
659 CurCoro.Data->ExceptionHandler);
660 auto *TryStmt =
661 CXXTryStmt::Create(getContext(), Loc, S.getBody(), &Catch);
662
663 EnterCXXTryStmt(*TryStmt);
664 emitBodyAndFallthrough(*this, S, TryStmt->getTryBlock());
665 ExitCXXTryStmt(*TryStmt);
666
667 if (ContBB)
668 EmitBlock(ContBB);
669 }
670 else {
671 emitBodyAndFallthrough(*this, S, S.getBody());
672 }
673
674 // See if we need to generate final suspend.
675 const bool CanFallthrough = Builder.GetInsertBlock();
676 const bool HasCoreturns = CurCoro.Data->CoreturnCount > 0;
677 if (CanFallthrough || HasCoreturns) {
678 EmitBlock(FinalBB);
679 CurCoro.Data->CurrentAwaitKind = AwaitKind::Final;
680 EmitStmt(S.getFinalSuspendStmt());
681 } else {
682 // We don't need FinalBB. Emit it to make sure the block is deleted.
683 EmitBlock(FinalBB, /*IsFinished=*/true);
684 }
685 }
686
687 EmitBlock(RetBB);
688 // Emit coro.end before getReturnStmt (and parameter destructors), since
689 // resume and destroy parts of the coroutine should not include them.
690 llvm::Function *CoroEnd = CGM.getIntrinsic(llvm::Intrinsic::coro_end);
691 Builder.CreateCall(CoroEnd, {NullPtr, Builder.getFalse()});
692
693 if (Stmt *Ret = S.getReturnStmt())
694 EmitStmt(Ret);
695}
696
697// Emit coroutine intrinsic and patch up arguments of the token type.
698RValue CodeGenFunction::EmitCoroutineIntrinsic(const CallExpr *E,
699 unsigned int IID) {
700 SmallVector<llvm::Value *, 8> Args;
701 switch (IID) {
702 default:
703 break;
704 // The coro.frame builtin is replaced with an SSA value of the coro.begin
705 // intrinsic.
706 case llvm::Intrinsic::coro_frame: {
707 if (CurCoro.Data && CurCoro.Data->CoroBegin) {
708 return RValue::get(CurCoro.Data->CoroBegin);
709 }
710 CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_begin "
711 "has been used earlier in this function");
712 auto NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
713 return RValue::get(NullPtr);
714 }
715 // The following three intrinsics take a token parameter referring to a token
716 // returned by earlier call to @llvm.coro.id. Since we cannot represent it in
717 // builtins, we patch it up here.
718 case llvm::Intrinsic::coro_alloc:
719 case llvm::Intrinsic::coro_begin:
720 case llvm::Intrinsic::coro_free: {
721 if (CurCoro.Data && CurCoro.Data->CoroId) {
722 Args.push_back(CurCoro.Data->CoroId);
723 break;
724 }
725 CGM.Error(E->getBeginLoc(), "this builtin expect that __builtin_coro_id has"
726 " been used earlier in this function");
727 // Fallthrough to the next case to add TokenNone as the first argument.
728 LLVM_FALLTHROUGH[[clang::fallthrough]];
729 }
730 // @llvm.coro.suspend takes a token parameter. Add token 'none' as the first
731 // argument.
732 case llvm::Intrinsic::coro_suspend:
733 Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
734 break;
735 }
736 for (auto &Arg : E->arguments())
737 Args.push_back(EmitScalarExpr(Arg));
738
739 llvm::Value *F = CGM.getIntrinsic(IID);
740 llvm::CallInst *Call = Builder.CreateCall(F, Args);
741
742 // Note: The following code is to enable to emit coro.id and coro.begin by
743 // hand to experiment with coroutines in C.
744 // If we see @llvm.coro.id remember it in the CoroData. We will update
745 // coro.alloc, coro.begin and coro.free intrinsics to refer to it.
746 if (IID == llvm::Intrinsic::coro_id) {
747 createCoroData(*this, CurCoro, Call, E);
748 }
749 else if (IID == llvm::Intrinsic::coro_begin) {
750 if (CurCoro.Data)
751 CurCoro.Data->CoroBegin = Call;
752 }
753 else if (IID == llvm::Intrinsic::coro_free) {
754 // Remember the last coro_free as we need it to build the conditional
755 // deletion of the coroutine frame.
756 if (CurCoro.Data)
757 CurCoro.Data->LastCoroFree = Call;
758 }
759 return RValue::get(Call);
760}