Bug Summary

File:tools/clang/lib/CodeGen/CGCoroutine.cpp
Warning:line 53, 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 "CodeGenFunction.h"
15#include "clang/AST/StmtCXX.h"
16
17using namespace clang;
18using namespace CodeGen;
19
20namespace clang {
21namespace CodeGen {
22
23struct CGCoroData {
24
25 // Stores the jump destination just before the final suspend. Coreturn
26 // statements jumps to this point after calling return_xxx promise member.
27 CodeGenFunction::JumpDest FinalJD;
28
29 unsigned CoreturnCount = 0;
30
31 // Stores the llvm.coro.id emitted in the function so that we can supply it
32 // as the first argument to coro.begin, coro.alloc and coro.free intrinsics.
33 // Note: llvm.coro.id returns a token that cannot be directly expressed in a
34 // builtin.
35 llvm::CallInst *CoroId = nullptr;
36 // If coro.id came from the builtin, remember the expression to give better
37 // diagnostic. If CoroIdExpr is nullptr, the coro.id was created by
38 // EmitCoroutineBody.
39 CallExpr const *CoroIdExpr = nullptr;
40};
41}
42}
43
44clang::CodeGen::CodeGenFunction::CGCoroInfo::CGCoroInfo() {}
45CodeGenFunction::CGCoroInfo::~CGCoroInfo() {}
46
47static void createCoroData(CodeGenFunction &CGF,
48 CodeGenFunction::CGCoroInfo &CurCoro,
49 llvm::CallInst *CoroId,
50 CallExpr const *CoroIdExpr = nullptr) {
51 if (CurCoro.Data) {
3
Taking true branch
52 if (CurCoro.Data->CoroIdExpr)
4
Assuming the condition is true
5
Taking true branch
53 CGF.CGM.Error(CoroIdExpr->getLocStart(),
6
Called C++ object pointer is null
54 "only one __builtin_coro_id can be used in a function");
55 else if (CoroIdExpr)
56 CGF.CGM.Error(CoroIdExpr->getLocStart(),
57 "__builtin_coro_id shall not be used in a C++ coroutine");
58 else
59 llvm_unreachable("EmitCoroutineBodyStatement called twice?")::llvm::llvm_unreachable_internal("EmitCoroutineBodyStatement called twice?"
, "/tmp/buildd/llvm-toolchain-snapshot-5.0~svn298304/tools/clang/lib/CodeGen/CGCoroutine.cpp"
, 59)
;
60
61 return;
62 }
63
64 CurCoro.Data = std::unique_ptr<CGCoroData>(new CGCoroData);
65 CurCoro.Data->CoroId = CoroId;
66 CurCoro.Data->CoroIdExpr = CoroIdExpr;
67}
68
69void CodeGenFunction::EmitCoreturnStmt(CoreturnStmt const &S) {
70 ++CurCoro.Data->CoreturnCount;
71 EmitStmt(S.getPromiseCall());
72 EmitBranchThroughCleanup(CurCoro.Data->FinalJD);
73}
74
75void CodeGenFunction::EmitCoroutineBody(const CoroutineBodyStmt &S) {
76 auto *NullPtr = llvm::ConstantPointerNull::get(Builder.getInt8PtrTy());
77 auto &TI = CGM.getContext().getTargetInfo();
78 unsigned NewAlign = TI.getNewAlign() / TI.getCharWidth();
79
80 auto *FinalBB = createBasicBlock("coro.final");
81
82 auto *CoroId = Builder.CreateCall(
83 CGM.getIntrinsic(llvm::Intrinsic::coro_id),
84 {Builder.getInt32(NewAlign), NullPtr, NullPtr, NullPtr});
85 createCoroData(*this, CurCoro, CoroId);
1
Passing null pointer value via 4th parameter 'CoroIdExpr'
2
Calling 'createCoroData'
86
87 EmitScalarExpr(S.getAllocate());
88
89 // FIXME: Setup cleanup scopes.
90
91 EmitStmt(S.getPromiseDeclStmt());
92
93 CurCoro.Data->FinalJD = getJumpDestInCurrentScope(FinalBB);
94
95 // FIXME: Emit initial suspend and more before the body.
96
97 EmitStmt(S.getBody());
98
99 // See if we need to generate final suspend.
100 const bool CanFallthrough = Builder.GetInsertBlock();
101 const bool HasCoreturns = CurCoro.Data->CoreturnCount > 0;
102 if (CanFallthrough || HasCoreturns) {
103 EmitBlock(FinalBB);
104 // FIXME: Emit final suspend.
105 }
106 EmitStmt(S.getDeallocate());
107
108 // FIXME: Emit return for the coroutine return object.
109}
110
111// Emit coroutine intrinsic and patch up arguments of the token type.
112RValue CodeGenFunction::EmitCoroutineIntrinsic(const CallExpr *E,
113 unsigned int IID) {
114 SmallVector<llvm::Value *, 8> Args;
115 switch (IID) {
116 default:
117 break;
118 // The following three intrinsics take a token parameter referring to a token
119 // returned by earlier call to @llvm.coro.id. Since we cannot represent it in
120 // builtins, we patch it up here.
121 case llvm::Intrinsic::coro_alloc:
122 case llvm::Intrinsic::coro_begin:
123 case llvm::Intrinsic::coro_free: {
124 if (CurCoro.Data && CurCoro.Data->CoroId) {
125 Args.push_back(CurCoro.Data->CoroId);
126 break;
127 }
128 CGM.Error(E->getLocStart(), "this builtin expect that __builtin_coro_id has"
129 " been used earlier in this function");
130 // Fallthrough to the next case to add TokenNone as the first argument.
131 }
132 // @llvm.coro.suspend takes a token parameter. Add token 'none' as the first
133 // argument.
134 case llvm::Intrinsic::coro_suspend:
135 Args.push_back(llvm::ConstantTokenNone::get(getLLVMContext()));
136 break;
137 }
138 for (auto &Arg : E->arguments())
139 Args.push_back(EmitScalarExpr(Arg));
140
141 llvm::Value *F = CGM.getIntrinsic(IID);
142 llvm::CallInst *Call = Builder.CreateCall(F, Args);
143
144 // If we see @llvm.coro.id remember it in the CoroData. We will update
145 // coro.alloc, coro.begin and coro.free intrinsics to refer to it.
146 if (IID == llvm::Intrinsic::coro_id) {
147 createCoroData(*this, CurCoro, Call, E);
148 }
149 return RValue::get(Call);
150}