140 lines · cpp
1//===-- ObjCARC.cpp -------------------------------------------------------===//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-exception6//7//===----------------------------------------------------------------------===//8//9// This file implements common infrastructure for libLLVMObjCARCOpts.a, which10// implements several scalar transformations over the LLVM intermediate11// representation, including the C bindings for that library.12//13//===----------------------------------------------------------------------===//14 15#include "ObjCARC.h"16#include "llvm/Analysis/ObjCARCUtil.h"17#include "llvm/IR/IRBuilder.h"18#include "llvm/IR/Instructions.h"19#include "llvm/Transforms/Utils/BasicBlockUtils.h"20 21using namespace llvm;22using namespace llvm::objcarc;23 24CallInst *objcarc::createCallInstWithColors(25 FunctionCallee Func, ArrayRef<Value *> Args, const Twine &NameStr,26 BasicBlock::iterator InsertBefore,27 const DenseMap<BasicBlock *, ColorVector> &BlockColors) {28 FunctionType *FTy = Func.getFunctionType();29 Value *Callee = Func.getCallee();30 SmallVector<OperandBundleDef, 1> OpBundles;31 32 if (!BlockColors.empty()) {33 const ColorVector &CV = BlockColors.find(InsertBefore->getParent())->second;34 assert(CV.size() == 1 && "non-unique color for block!");35 BasicBlock::iterator EHPad = CV.front()->getFirstNonPHIIt();36 if (EHPad->isEHPad())37 OpBundles.emplace_back("funclet", &*EHPad);38 }39 40 return CallInst::Create(FTy, Callee, Args, OpBundles, NameStr, InsertBefore);41}42 43std::pair<bool, bool>44BundledRetainClaimRVs::insertAfterInvokes(Function &F, DominatorTree *DT) {45 bool Changed = false, CFGChanged = false;46 47 for (BasicBlock &BB : F) {48 auto *I = dyn_cast<InvokeInst>(BB.getTerminator());49 50 if (!I)51 continue;52 53 if (!objcarc::hasAttachedCallOpBundle(I))54 continue;55 56 BasicBlock *DestBB = I->getNormalDest();57 58 if (!DestBB->getSinglePredecessor()) {59 assert(I->getSuccessor(0) == DestBB &&60 "the normal dest is expected to be the first successor");61 DestBB = SplitCriticalEdge(I, 0, CriticalEdgeSplittingOptions(DT));62 CFGChanged = true;63 }64 65 // We don't have to call insertRVCallWithColors since DestBB is the normal66 // destination of the invoke.67 insertRVCall(DestBB->getFirstInsertionPt(), I);68 Changed = true;69 }70 71 return std::make_pair(Changed, CFGChanged);72}73 74CallInst *BundledRetainClaimRVs::insertRVCall(BasicBlock::iterator InsertPt,75 CallBase *AnnotatedCall) {76 DenseMap<BasicBlock *, ColorVector> BlockColors;77 return insertRVCallWithColors(InsertPt, AnnotatedCall, BlockColors);78}79 80CallInst *BundledRetainClaimRVs::insertRVCallWithColors(81 BasicBlock::iterator InsertPt, CallBase *AnnotatedCall,82 const DenseMap<BasicBlock *, ColorVector> &BlockColors) {83 IRBuilder<> Builder(InsertPt->getParent(), InsertPt);84 Function *Func = *objcarc::getAttachedARCFunction(AnnotatedCall);85 assert(Func && "operand isn't a Function");86 Type *ParamTy = Func->getArg(0)->getType();87 Value *CallArg = Builder.CreateBitCast(AnnotatedCall, ParamTy);88 auto *Call =89 createCallInstWithColors(Func, CallArg, "", InsertPt, BlockColors);90 RVCalls[Call] = AnnotatedCall;91 return Call;92}93 94BundledRetainClaimRVs::~BundledRetainClaimRVs() {95 for (auto P : RVCalls) {96 if (ContractPass) {97 CallBase *CB = P.second;98 // At this point, we know that the annotated calls can't be tail calls99 // as they are followed by marker instructions and retainRV/claimRV100 // calls. Mark them as notail so that the backend knows these calls101 // can't be tail calls.102 if (auto *CI = dyn_cast<CallInst>(CB))103 CI->setTailCallKind(CallInst::TCK_NoTail);104 105 // We can also do one final optimization: modify the bundle in the106 // annotated call, to change the bundle operand from107 // objc_retainAutoreleasedReturnValue108 // to:109 // objc_claimAutoreleasedReturnValue110 // allowing the marker to be omitted from the bundle expansion later.111 //112 // Note that, confusingly, ClaimRV is semantically equivalent to RetainRV,113 // and only differs in that it doesn't require the marker.114 // The bundle provides the guarantee that we're emitting the ClaimRV call115 // adjacent to the original call, and providing that guarantee is the116 // only difference between ClaimRV and RetainRV.117 //118 // UnsafeClaimRV has a different RC contract entirely.119 120 // Find the clang.arc.attachedcall bundle, and rewrite its operand.121 if (UseClaimRV) {122 for (auto OBI : CB->bundle_op_infos()) {123 auto OBU = CB->operandBundleFromBundleOpInfo(OBI);124 if (OBU.getTagID() == LLVMContext::OB_clang_arc_attachedcall &&125 OBU.Inputs[0] == EP.get(ARCRuntimeEntryPointKind::RetainRV)) {126 CB->setOperand(OBI.Begin,127 EP.get(ARCRuntimeEntryPointKind::ClaimRV));128 break;129 }130 }131 }132 }133 134 // Erase the RV call we emitted earlier: it's already in the bundle.135 EraseInstruction(P.first);136 }137 138 RVCalls.clear();139}140