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183119cdf6
Reg2Mem for fun you can opt -reg2mem -mem2reg git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24267 91177308-0d34-0410-b5e6-96231b3b80d8
80 lines
2.7 KiB
C++
80 lines
2.7 KiB
C++
//===- Reg2Mem.cpp - Convert registers to allocas -------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file demotes all registers to memory references. It is intented to be
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// the inverse of PromoteMemoryToRegister. By converting to loads, the only
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// values live accross basic blocks are allocas and loads before phi nodes.
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// It is intended that this should make CFG hacking much easier.
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// To make later hacking easier, the entry block is split into two, such that
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// all introduced allocas and nothing else are in the entry block.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/Pass.h"
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#include "llvm/Function.h"
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#include "llvm/Module.h"
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#include "llvm/BasicBlock.h"
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#include "llvm/Instructions.h"
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#include "llvm/ADT/Statistic.h"
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#include <list>
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using namespace llvm;
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namespace {
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Statistic<> NumDemoted("reg2mem", "Number of registers demoted");
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struct RegToMem : public FunctionPass {
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bool valueEscapes(Instruction* i) {
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BasicBlock* bb = i->getParent();
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for(Value::use_iterator ii = i->use_begin(), ie = i->use_end();
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ii != ie; ++ii)
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if (cast<Instruction>(*ii)->getParent() != bb)
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return true;
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return false;
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}
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virtual bool runOnFunction(Function &F) {
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if (!F.isExternal()) {
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//give us a clean block
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BasicBlock& bbhead = F.getEntryBlock();
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bbhead.splitBasicBlock(bbhead.begin());
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//find the instructions
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std::list<Instruction*> worklist;
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for (Function::iterator ibb = F.begin(), ibe = F.end();
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ibb != ibe; ++ibb)
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for (BasicBlock::iterator iib = ibb->begin(), iie = ibb->end();
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iib != iie; ++iib) {
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if(valueEscapes(iib))
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worklist.push_front(&*iib);
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}
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//demote escaped instructions
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NumDemoted += worklist.size();
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for (std::list<Instruction*>::iterator ilb = worklist.begin(),
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ile = worklist.end(); ilb != ile; ++ilb)
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DemoteRegToStack(**ilb, false);
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return true;
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}
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return false;
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}
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};
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RegisterOpt<RegToMem> X("reg2mem", "Demote all values to stack slots");
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}
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// createDemoteRegisterToMemory - Provide an entry point to create this pass.
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//
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FunctionPass *llvm::createDemoteRegisterToMemoryPass() {
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return new RegToMem();
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}
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