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//===- PreISelIntrinsicLowering.cpp - Pre-ISel intrinsic lowering pass ----===//
//
// 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 pass implements IR lowering for the llvm.load.relative and llvm.objc.*
// intrinsics.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/PreISelIntrinsicLowering.h"
#include "llvm/Analysis/ObjCARCInstKind.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/User.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Casting.h"
using namespace llvm;
static bool lowerLoadRelative(Function &F) {
if (F.use_empty())
return false;
bool Changed = false;
Type *Int32Ty = Type::getInt32Ty(F.getContext());
Type *Int32PtrTy = Int32Ty->getPointerTo();
Type *Int8Ty = Type::getInt8Ty(F.getContext());
for (auto I = F.use_begin(), E = F.use_end(); I != E;) {
auto CI = dyn_cast<CallInst>(I->getUser());
++I;
if (!CI || CI->getCalledValue() != &F)
continue;
IRBuilder<> B(CI);
Value *OffsetPtr =
B.CreateGEP(Int8Ty, CI->getArgOperand(0), CI->getArgOperand(1));
Value *OffsetPtrI32 = B.CreateBitCast(OffsetPtr, Int32PtrTy);
Value *OffsetI32 = B.CreateAlignedLoad(Int32Ty, OffsetPtrI32, 4);
Value *ResultPtr = B.CreateGEP(Int8Ty, CI->getArgOperand(0), OffsetI32);
CI->replaceAllUsesWith(ResultPtr);
CI->eraseFromParent();
Changed = true;
}
return Changed;
}
// ObjCARC has knowledge about whether an obj-c runtime function needs to be
// always tail-called or never tail-called.
static CallInst::TailCallKind getOverridingTailCallKind(const Function &F) {
objcarc::ARCInstKind Kind = objcarc::GetFunctionClass(&F);
if (objcarc::IsAlwaysTail(Kind))
return CallInst::TCK_Tail;
else if (objcarc::IsNeverTail(Kind))
return CallInst::TCK_NoTail;
return CallInst::TCK_None;
}
static bool lowerObjCCall(Function &F, const char *NewFn,
bool setNonLazyBind = false) {
if (F.use_empty())
return false;
// If we haven't already looked up this function, check to see if the
// program already contains a function with this name.
Module *M = F.getParent();
FunctionCallee FCache = M->getOrInsertFunction(NewFn, F.getFunctionType());
if (Function *Fn = dyn_cast<Function>(FCache.getCallee())) {
Fn->setLinkage(F.getLinkage());
if (setNonLazyBind && !Fn->isWeakForLinker()) {
// If we have Native ARC, set nonlazybind attribute for these APIs for
// performance.
Fn->addFnAttr(Attribute::NonLazyBind);
}
}
CallInst::TailCallKind OverridingTCK = getOverridingTailCallKind(F);
for (auto I = F.use_begin(), E = F.use_end(); I != E;) {
auto *CI = cast<CallInst>(I->getUser());
assert(CI->getCalledFunction() && "Cannot lower an indirect call!");
++I;
IRBuilder<> Builder(CI->getParent(), CI->getIterator());
SmallVector<Value *, 8> Args(CI->arg_begin(), CI->arg_end());
CallInst *NewCI = Builder.CreateCall(FCache, Args);
NewCI->setName(CI->getName());
// Try to set the most appropriate TailCallKind based on both the current
// attributes and the ones that we could get from ObjCARC's special
// knowledge of the runtime functions.
//
// std::max respects both requirements of notail and tail here:
// * notail on either the call or from ObjCARC becomes notail
// * tail on either side is stronger than none, but not notail
CallInst::TailCallKind TCK = CI->getTailCallKind();
NewCI->setTailCallKind(std::max(TCK, OverridingTCK));
if (!CI->use_empty())
CI->replaceAllUsesWith(NewCI);
CI->eraseFromParent();
}
return true;
}
static bool lowerIntrinsics(Module &M) {
bool Changed = false;
for (Function &F : M) {
if (F.getName().startswith("llvm.load.relative.")) {
Changed |= lowerLoadRelative(F);
continue;
}
switch (F.getIntrinsicID()) {
default:
break;
case Intrinsic::objc_autorelease:
Changed |= lowerObjCCall(F, "objc_autorelease");
break;
case Intrinsic::objc_autoreleasePoolPop:
Changed |= lowerObjCCall(F, "objc_autoreleasePoolPop");
break;
case Intrinsic::objc_autoreleasePoolPush:
Changed |= lowerObjCCall(F, "objc_autoreleasePoolPush");
break;
case Intrinsic::objc_autoreleaseReturnValue:
Changed |= lowerObjCCall(F, "objc_autoreleaseReturnValue");
break;
case Intrinsic::objc_copyWeak:
Changed |= lowerObjCCall(F, "objc_copyWeak");
break;
case Intrinsic::objc_destroyWeak:
Changed |= lowerObjCCall(F, "objc_destroyWeak");
break;
case Intrinsic::objc_initWeak:
Changed |= lowerObjCCall(F, "objc_initWeak");
break;
case Intrinsic::objc_loadWeak:
Changed |= lowerObjCCall(F, "objc_loadWeak");
break;
case Intrinsic::objc_loadWeakRetained:
Changed |= lowerObjCCall(F, "objc_loadWeakRetained");
break;
case Intrinsic::objc_moveWeak:
Changed |= lowerObjCCall(F, "objc_moveWeak");
break;
case Intrinsic::objc_release:
Changed |= lowerObjCCall(F, "objc_release", true);
break;
case Intrinsic::objc_retain:
Changed |= lowerObjCCall(F, "objc_retain", true);
break;
case Intrinsic::objc_retainAutorelease:
Changed |= lowerObjCCall(F, "objc_retainAutorelease");
break;
case Intrinsic::objc_retainAutoreleaseReturnValue:
Changed |= lowerObjCCall(F, "objc_retainAutoreleaseReturnValue");
break;
case Intrinsic::objc_retainAutoreleasedReturnValue:
Changed |= lowerObjCCall(F, "objc_retainAutoreleasedReturnValue");
break;
case Intrinsic::objc_retainBlock:
Changed |= lowerObjCCall(F, "objc_retainBlock");
break;
case Intrinsic::objc_storeStrong:
Changed |= lowerObjCCall(F, "objc_storeStrong");
break;
case Intrinsic::objc_storeWeak:
Changed |= lowerObjCCall(F, "objc_storeWeak");
break;
case Intrinsic::objc_unsafeClaimAutoreleasedReturnValue:
Changed |= lowerObjCCall(F, "objc_unsafeClaimAutoreleasedReturnValue");
break;
case Intrinsic::objc_retainedObject:
Changed |= lowerObjCCall(F, "objc_retainedObject");
break;
case Intrinsic::objc_unretainedObject:
Changed |= lowerObjCCall(F, "objc_unretainedObject");
break;
case Intrinsic::objc_unretainedPointer:
Changed |= lowerObjCCall(F, "objc_unretainedPointer");
break;
case Intrinsic::objc_retain_autorelease:
Changed |= lowerObjCCall(F, "objc_retain_autorelease");
break;
case Intrinsic::objc_sync_enter:
Changed |= lowerObjCCall(F, "objc_sync_enter");
break;
case Intrinsic::objc_sync_exit:
Changed |= lowerObjCCall(F, "objc_sync_exit");
break;
}
}
return Changed;
}
namespace {
class PreISelIntrinsicLoweringLegacyPass : public ModulePass {
public:
static char ID;
PreISelIntrinsicLoweringLegacyPass() : ModulePass(ID) {}
bool runOnModule(Module &M) override { return lowerIntrinsics(M); }
};
} // end anonymous namespace
char PreISelIntrinsicLoweringLegacyPass::ID;
INITIALIZE_PASS(PreISelIntrinsicLoweringLegacyPass,
"pre-isel-intrinsic-lowering", "Pre-ISel Intrinsic Lowering",
false, false)
ModulePass *llvm::createPreISelIntrinsicLoweringPass() {
return new PreISelIntrinsicLoweringLegacyPass;
}
PreservedAnalyses PreISelIntrinsicLoweringPass::run(Module &M,
ModuleAnalysisManager &AM) {
if (!lowerIntrinsics(M))
return PreservedAnalyses::all();
else
return PreservedAnalyses::none();
}
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