1//===- ObjCARC.h - ObjC ARC Optimization --------------*- C++ -*-----------===//
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/// \file
9/// This file defines common definitions/declarations used by the ObjC ARC
10/// Optimizer. ARC stands for Automatic Reference Counting and is a system for
11/// managing reference counts for objects in Objective C.
12///
13/// WARNING: This file knows about certain library functions. It recognizes them
14/// by name, and hardwires knowledge of their semantics.
15///
16/// WARNING: This file knows about how certain Objective-C library functions are
17/// used. Naive LLVM IR transformations which would otherwise be
18/// behavior-preserving may break these assumptions.
19///
20//===----------------------------------------------------------------------===//
21
22#ifndef LLVM_LIB_TRANSFORMS_OBJCARC_OBJCARC_H
23#define LLVM_LIB_TRANSFORMS_OBJCARC_OBJCARC_H
24
25#include "ARCRuntimeEntryPoints.h"
26#include "llvm/Analysis/ObjCARCAnalysisUtils.h"
27#include "llvm/Analysis/ObjCARCUtil.h"
28#include "llvm/IR/EHPersonalities.h"
29#include "llvm/Transforms/Utils/Local.h"
30
31namespace llvm {
32namespace objcarc {
33
34/// Erase the given instruction.
35///
36/// Many ObjC calls return their argument verbatim,
37/// so if it's such a call and the return value has users, replace them with the
38/// argument value.
39///
40static inline void EraseInstruction(Instruction *CI) {
41 Value *OldArg = cast<CallInst>(Val: CI)->getArgOperand(i: 0);
42
43 bool Unused = CI->use_empty();
44
45 if (!Unused) {
46 // Replace the return value with the argument.
47 assert((IsForwarding(GetBasicARCInstKind(CI)) ||
48 (IsNoopOnNull(GetBasicARCInstKind(CI)) &&
49 IsNullOrUndef(OldArg->stripPointerCasts()))) &&
50 "Can't delete non-forwarding instruction with users!");
51 CI->replaceAllUsesWith(V: OldArg);
52 }
53
54 CI->eraseFromParent();
55
56 if (Unused)
57 RecursivelyDeleteTriviallyDeadInstructions(V: OldArg);
58}
59
60/// If Inst is a ReturnRV and its operand is a call or invoke, return the
61/// operand. Otherwise return null.
62static inline const Instruction *getreturnRVOperand(const Instruction &Inst,
63 ARCInstKind Class) {
64 if (Class != ARCInstKind::RetainRV)
65 return nullptr;
66
67 const auto *Opnd = Inst.getOperand(i: 0)->stripPointerCasts();
68 if (const auto *C = dyn_cast<CallInst>(Val: Opnd))
69 return C;
70 return dyn_cast<InvokeInst>(Val: Opnd);
71}
72
73/// Return the list of PHI nodes that are equivalent to PN.
74template<class PHINodeTy, class VectorTy>
75void getEquivalentPHIs(PHINodeTy &PN, VectorTy &PHIList) {
76 auto *BB = PN.getParent();
77 for (auto &P : BB->phis()) {
78 if (&P == &PN) // Do not add PN to the list.
79 continue;
80 unsigned I = 0, E = PN.getNumIncomingValues();
81 for (; I < E; ++I) {
82 auto *BB = PN.getIncomingBlock(I);
83 auto *PNOpnd = PN.getIncomingValue(I)->stripPointerCasts();
84 auto *POpnd = P.getIncomingValueForBlock(BB)->stripPointerCasts();
85 if (PNOpnd != POpnd)
86 break;
87 }
88 if (I == E)
89 PHIList.push_back(&P);
90 }
91}
92
93static inline MDString *getRVInstMarker(Module &M) {
94 const char *MarkerKey = getRVMarkerModuleFlagStr();
95 return dyn_cast_or_null<MDString>(Val: M.getModuleFlag(Key: MarkerKey));
96}
97
98/// Create a call instruction with the correct funclet token. This should be
99/// called instead of calling CallInst::Create directly unless the call is
100/// going to be removed from the IR before WinEHPrepare.
101CallInst *createCallInstWithColors(
102 FunctionCallee Func, ArrayRef<Value *> Args, const Twine &NameStr,
103 BasicBlock::iterator InsertBefore,
104 const DenseMap<BasicBlock *, ColorVector> &BlockColors);
105
106class BundledRetainClaimRVs {
107public:
108 BundledRetainClaimRVs(ARCRuntimeEntryPoints &EP, bool ContractPass,
109 bool UseClaimRV)
110 : EP(EP), ContractPass(ContractPass), UseClaimRV(UseClaimRV) {}
111 ~BundledRetainClaimRVs();
112
113 /// Insert a retainRV/claimRV call to the normal destination blocks of invokes
114 /// with operand bundle "clang.arc.attachedcall". If the edge to the normal
115 /// destination block is a critical edge, split it.
116 std::pair<bool, bool> insertAfterInvokes(Function &F, DominatorTree *DT);
117
118 /// Insert a retainRV/claimRV call.
119 CallInst *insertRVCall(BasicBlock::iterator InsertPt,
120 CallBase *AnnotatedCall);
121
122 /// Insert a retainRV/claimRV call with colors.
123 CallInst *insertRVCallWithColors(
124 BasicBlock::iterator InsertPt, CallBase *AnnotatedCall,
125 const DenseMap<BasicBlock *, ColorVector> &BlockColors);
126
127 /// See if an instruction is a bundled retainRV/claimRV call.
128 bool contains(const Instruction *I) const {
129 if (auto *CI = dyn_cast<CallInst>(Val: I))
130 return RVCalls.count(Val: CI);
131 return false;
132 }
133
134 /// Remove a retainRV/claimRV call entirely.
135 void eraseInst(CallInst *CI) {
136 auto It = RVCalls.find(Val: CI);
137 if (It != RVCalls.end()) {
138 // Remove call to @llvm.objc.clang.arc.noop.use.
139 for (User *U : It->second->users())
140 if (auto *CI = dyn_cast<CallInst>(Val: U))
141 if (CI->getIntrinsicID() == Intrinsic::objc_clang_arc_noop_use) {
142 CI->eraseFromParent();
143 break;
144 }
145
146 auto *NewCall = CallBase::removeOperandBundle(
147 CB: It->second, ID: LLVMContext::OB_clang_arc_attachedcall,
148 InsertPt: It->second->getIterator());
149 NewCall->copyMetadata(SrcInst: *It->second);
150 It->second->replaceAllUsesWith(V: NewCall);
151 It->second->eraseFromParent();
152 RVCalls.erase(I: It);
153 }
154 EraseInstruction(CI);
155 }
156
157private:
158 /// A map of inserted retainRV/claimRV calls to annotated calls/invokes.
159 DenseMap<CallInst *, CallBase *> RVCalls;
160
161 ARCRuntimeEntryPoints &EP;
162 bool ContractPass;
163 bool UseClaimRV;
164};
165
166} // end namespace objcarc
167} // end namespace llvm
168
169#endif
170