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/*
* Copyright 2012, The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "ExpandVAArgPass.h"
#include <llvm/ADT/Triple.h>
#include <llvm/IR/DataLayout.h>
#include <llvm/IR/DerivedTypes.h>
#include <llvm/IR/Function.h>
#include <llvm/IR/IRBuilder.h>
#include <llvm/IR/Instructions.h>
#include <llvm/IR/Module.h>
#include <llvm/IR/Type.h>
#include <llvm/Pass.h>
class X86ExpandVAArg : public ExpandVAArgPass {
public:
virtual const char *getPassName() const {
return "X86 LLVM va_arg Instruction Expansion Pass";
}
private:
// Derivative work from clang/lib/CodeGen/TargetInfo.cpp.
virtual llvm::Value *expandVAArg(llvm::Instruction *pInst) {
llvm::Type *pty = pInst->getType();
llvm::Type *ty = pty->getContainedType(0);
llvm::Value *va_list_addr = pInst->getOperand(0);
llvm::IRBuilder<> builder(pInst);
const llvm::DataLayoutPass *dlp =
getAnalysisIfAvailable<llvm::DataLayoutPass>();
const llvm::DataLayout *dl = &dlp->getDataLayout();
llvm::Type *bp = llvm::Type::getInt8PtrTy(*mContext);
llvm::Type *bpp = bp->getPointerTo(0);
llvm::Value *va_list_addr_bpp = builder.CreateBitCast(va_list_addr,
bpp, "ap");
llvm::Value *addr = builder.CreateLoad(va_list_addr_bpp, "ap.cur");
llvm::Value *addr_typed = builder.CreateBitCast(addr, pty);
// X86-32 stack type alignment is always 4.
uint64_t offset = llvm::RoundUpToAlignment(dl->getTypeSizeInBits(ty)/8, 4);
llvm::Value *next_addr = builder.CreateGEP(addr,
llvm::ConstantInt::get(llvm::Type::getInt32Ty(*mContext), offset),
"ap.next");
builder.CreateStore(next_addr, va_list_addr_bpp);
return addr_typed;
}
}; // end X86ExpandVAArg
ExpandVAArgPass* createX86ExpandVAArgPass() {
return new X86ExpandVAArg();
}
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