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//===-- ObjCARC.cpp -------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements common infrastructure for libLLVMObjCARCOpts.a, which
// implements several scalar transformations over the LLVM intermediate
// representation, including the C bindings for that library.
//
//===----------------------------------------------------------------------===//
#include "ObjCARC.h"
#include "llvm/Analysis/ObjCARCUtil.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
using namespace llvm;
using namespace llvm::objcarc;
CallInst *objcarc::createCallInstWithColors(
FunctionCallee Func, ArrayRef<Value *> Args, const Twine &NameStr,
BasicBlock::iterator InsertBefore,
const DenseMap<BasicBlock *, ColorVector> &BlockColors) {
FunctionType *FTy = Func.getFunctionType();
Value *Callee = Func.getCallee();
SmallVector<OperandBundleDef, 1> OpBundles;
if (!BlockColors.empty()) {
const ColorVector &CV = BlockColors.find(InsertBefore->getParent())->second;
assert(CV.size() == 1 && "non-unique color for block!");
BasicBlock::iterator EHPad = CV.front()->getFirstNonPHIIt();
if (EHPad->isEHPad())
OpBundles.emplace_back("funclet", &*EHPad);
}
return CallInst::Create(FTy, Callee, Args, OpBundles, NameStr, InsertBefore);
}
std::pair<bool, bool>
BundledRetainClaimRVs::insertAfterInvokes(Function &F, DominatorTree *DT) {
bool Changed = false, CFGChanged = false;
for (BasicBlock &BB : F) {
auto *I = dyn_cast<InvokeInst>(BB.getTerminator());
if (!I)
continue;
if (!objcarc::hasAttachedCallOpBundle(I))
continue;
BasicBlock *DestBB = I->getNormalDest();
if (!DestBB->getSinglePredecessor()) {
assert(I->getSuccessor(0) == DestBB &&
"the normal dest is expected to be the first successor");
DestBB = SplitCriticalEdge(I, 0, CriticalEdgeSplittingOptions(DT));
CFGChanged = true;
}
// We don't have to call insertRVCallWithColors since DestBB is the normal
// destination of the invoke.
insertRVCall(DestBB->getFirstInsertionPt(), I);
Changed = true;
}
return std::make_pair(Changed, CFGChanged);
}
CallInst *BundledRetainClaimRVs::insertRVCall(BasicBlock::iterator InsertPt,
CallBase *AnnotatedCall) {
DenseMap<BasicBlock *, ColorVector> BlockColors;
return insertRVCallWithColors(InsertPt, AnnotatedCall, BlockColors);
}
CallInst *BundledRetainClaimRVs::insertRVCallWithColors(
BasicBlock::iterator InsertPt, CallBase *AnnotatedCall,
const DenseMap<BasicBlock *, ColorVector> &BlockColors) {
IRBuilder<> Builder(InsertPt->getParent(), InsertPt);
Function *Func = *objcarc::getAttachedARCFunction(AnnotatedCall);
assert(Func && "operand isn't a Function");
Type *ParamTy = Func->getArg(0)->getType();
Value *CallArg = Builder.CreateBitCast(AnnotatedCall, ParamTy);
auto *Call =
createCallInstWithColors(Func, CallArg, "", InsertPt, BlockColors);
RVCalls[Call] = AnnotatedCall;
return Call;
}
BundledRetainClaimRVs::~BundledRetainClaimRVs() {
for (auto P : RVCalls) {
if (ContractPass) {
CallBase *CB = P.second;
// At this point, we know that the annotated calls can't be tail calls
// as they are followed by marker instructions and retainRV/claimRV
// calls. Mark them as notail so that the backend knows these calls
// can't be tail calls.
if (auto *CI = dyn_cast<CallInst>(CB))
CI->setTailCallKind(CallInst::TCK_NoTail);
// We can also do one final optimization: modify the bundle in the
// annotated call, to change the bundle operand from
// objc_retainAutoreleasedReturnValue
// to:
// objc_claimAutoreleasedReturnValue
// allowing the marker to be omitted from the bundle expansion later.
//
// Note that, confusingly, ClaimRV is semantically equivalent to RetainRV,
// and only differs in that it doesn't require the marker.
// The bundle provides the guarantee that we're emitting the ClaimRV call
// adjacent to the original call, and providing that guarantee is the
// only difference between ClaimRV and RetainRV.
//
// UnsafeClaimRV has a different RC contract entirely.
// Find the clang.arc.attachedcall bundle, and rewrite its operand.
if (UseClaimRV) {
for (auto OBI : CB->bundle_op_infos()) {
auto OBU = CB->operandBundleFromBundleOpInfo(OBI);
if (OBU.getTagID() == LLVMContext::OB_clang_arc_attachedcall &&
OBU.Inputs[0] == EP.get(ARCRuntimeEntryPointKind::RetainRV)) {
CB->setOperand(OBI.Begin,
EP.get(ARCRuntimeEntryPointKind::ClaimRV));
break;
}
}
}
}
// Erase the RV call we emitted earlier: it's already in the bundle.
EraseInstruction(P.first);
}
RVCalls.clear();
}
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