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