llvm/lib/Transforms/IPO/IndMemRemoval.cpp
Reid Spencer 3ed469ccd7 For PR786:
Turn on -Wunused and -Wno-unused-parameter. Clean up most of the resulting
fall out by removing unused variables. Remaining warnings have to do with
unused functions (I didn't want to delete code without review) and unused
variables in generated code. Maintainers should clean up the remaining
issues when they see them. All changes pass DejaGnu tests and Olden.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31380 91177308-0d34-0410-b5e6-96231b3b80d8
2006-11-02 20:25:50 +00:00

93 lines
3.1 KiB
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//===-- IndMemRemoval.cpp - Remove indirect allocations and frees ----------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass finds places where memory allocation functions may escape into
// indirect land. Some transforms are much easier (aka possible) only if free
// or malloc are not called indirectly.
// Thus find places where the address of memory functions are taken and construct
// bounce functions with direct calls of those functions.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/IPO.h"
#include "llvm/Pass.h"
#include "llvm/Module.h"
#include "llvm/Function.h"
#include "llvm/Instructions.h"
#include "llvm/Type.h"
#include "llvm/Support/Debug.h"
#include "llvm/ADT/Statistic.h"
#include <fstream>
#include <iostream>
#include <set>
using namespace llvm;
namespace {
Statistic<> NumBounceSites("indmemrem", "Number of sites modified");
Statistic<> NumBounce ("indmemrem", "Number of bounce functions created");
class IndMemRemPass : public ModulePass {
public:
IndMemRemPass();
virtual bool runOnModule(Module &M);
};
RegisterPass<IndMemRemPass> X("indmemrem","Indirect Malloc and Free Removal");
} // end anonymous namespace
IndMemRemPass::IndMemRemPass()
{
}
bool IndMemRemPass::runOnModule(Module &M) {
//in Theory, all direct calls of malloc and free should be promoted
//to intrinsics. Therefor, this goes through and finds where the
//address of free or malloc are taken and replaces those with bounce
//functions, ensuring that all malloc and free that might happen
//happen through intrinsics.
bool changed = false;
if (Function* F = M.getNamedFunction("free")) {
assert(F->isExternal() && "free not external?");
if (!F->use_empty()) {
Function* FN = new Function(F->getFunctionType(),
GlobalValue::LinkOnceLinkage,
"free_llvm_bounce", &M);
BasicBlock* bb = new BasicBlock("entry",FN);
Instruction* R = new ReturnInst(bb);
new FreeInst(FN->arg_begin(), R);
++NumBounce;
NumBounceSites += F->getNumUses();
F->replaceAllUsesWith(FN);
changed = true;
}
}
if (Function* F = M.getNamedFunction("malloc")) {
assert(F->isExternal() && "malloc not external?");
if (!F->use_empty()) {
Function* FN = new Function(F->getFunctionType(),
GlobalValue::LinkOnceLinkage,
"malloc_llvm_bounce", &M);
BasicBlock* bb = new BasicBlock("entry",FN);
Instruction* c = new CastInst(FN->arg_begin(), Type::UIntTy, "c", bb);
Instruction* a = new MallocInst(Type::SByteTy, c, "m", bb);
new ReturnInst(a, bb);
++NumBounce;
NumBounceSites += F->getNumUses();
F->replaceAllUsesWith(FN);
changed = true;
}
}
return changed;
}
ModulePass *llvm::createIndMemRemPass() {
return new IndMemRemPass();
}