llvm-project/llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp

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//===-- PreISelIntrinsicLowering.cpp - Pre-ISel intrinsic lowering pass ---===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass implements IR lowering for the llvm.load.relative intrinsic.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/PreISelIntrinsicLowering.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/Pass.h"
using namespace llvm;
namespace {
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(OffsetPtrI32, 4);
Value *ResultPtr = B.CreateGEP(Int8Ty, CI->getArgOperand(0), OffsetI32);
CI->replaceAllUsesWith(ResultPtr);
CI->eraseFromParent();
Changed = true;
}
return Changed;
}
bool lowerIntrinsics(Module &M) {
bool Changed = false;
for (Function &F : M) {
if (F.getName().startswith("llvm.load.relative."))
Changed |= lowerLoadRelative(F);
}
return Changed;
}
class PreISelIntrinsicLoweringLegacyPass : public ModulePass {
public:
static char ID;
PreISelIntrinsicLoweringLegacyPass() : ModulePass(ID) {}
bool runOnModule(Module &M) { return lowerIntrinsics(M); }
};
char PreISelIntrinsicLoweringLegacyPass::ID;
}
INITIALIZE_PASS(PreISelIntrinsicLoweringLegacyPass,
"pre-isel-intrinsic-lowering", "Pre-ISel Intrinsic Lowering",
false, false)
namespace llvm {
ModulePass *createPreISelIntrinsicLoweringPass() {
return new PreISelIntrinsicLoweringLegacyPass;
}
PreservedAnalyses PreISelIntrinsicLoweringPass::run(Module &M,
ModuleAnalysisManager &AM) {
if (!lowerIntrinsics(M))
return PreservedAnalyses::all();
else
return PreservedAnalyses::none();
}
} // End llvm namespace