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/EHPersonalities.h" 26 #include "llvm/Analysis/ObjCARCAnalysisUtils.h" 27 #include "llvm/Analysis/ObjCARCUtil.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 /// 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. 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> 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 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 Instruction *InsertBefore, 103 const DenseMap<BasicBlock *, ColorVector> &BlockColors); 104 105 class BundledRetainClaimRVs { 106 public: 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(Instruction *InsertPt, CallBase *AnnotatedCall); 117 118 /// Insert a retainRV/claimRV call with colors. 119 CallInst *insertRVCallWithColors( 120 Instruction *InsertPt, CallBase *AnnotatedCall, 121 const DenseMap<BasicBlock *, ColorVector> &BlockColors); 122 123 /// See if an instruction is a bundled retainRV/claimRV call. 124 bool contains(const Instruction *I) const { 125 if (auto *CI = dyn_cast<CallInst>(I)) 126 return RVCalls.count(CI); 127 return false; 128 } 129 130 /// Remove a retainRV/claimRV call entirely. 131 void eraseInst(CallInst *CI) { 132 auto It = RVCalls.find(CI); 133 if (It != RVCalls.end()) { 134 // Remove call to @llvm.objc.clang.arc.noop.use. 135 for (auto U = It->second->user_begin(), E = It->second->user_end(); U != E; ++U) 136 if (auto *CI = dyn_cast<CallInst>(*U)) 137 if (CI->getIntrinsicID() == Intrinsic::objc_clang_arc_noop_use) { 138 CI->eraseFromParent(); 139 break; 140 } 141 142 auto *NewCall = CallBase::removeOperandBundle( 143 It->second, LLVMContext::OB_clang_arc_attachedcall, It->second); 144 NewCall->copyMetadata(*It->second); 145 It->second->replaceAllUsesWith(NewCall); 146 It->second->eraseFromParent(); 147 RVCalls.erase(It); 148 } 149 EraseInstruction(CI); 150 } 151 152 private: 153 /// A map of inserted retainRV/claimRV calls to annotated calls/invokes. 154 DenseMap<CallInst *, CallBase *> RVCalls; 155 156 bool ContractPass; 157 }; 158 159 } // end namespace objcarc 160 } // end namespace llvm 161 162 #endif 163