llvm/lib/Transforms/IPO/IndMemRemoval.cpp
Victor Hernandez 13ad5aaaff Autoupgrade malloc insts to malloc calls.
Update testcases that rely on malloc insts being present.

Also prematurely remove MallocInst handling from IndMemRemoval and RaiseAllocations to help pass tests in this incremental step.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84292 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-17 00:00:19 +00:00

100 lines
3.8 KiB
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//===-- IndMemRemoval.cpp - Remove indirect allocations and frees ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file 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.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "indmemrem"
#include "llvm/Transforms/IPO.h"
#include "llvm/Pass.h"
#include "llvm/Module.h"
#include "llvm/Instructions.h"
#include "llvm/Type.h"
#include "llvm/DerivedTypes.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Target/TargetData.h"
using namespace llvm;
STATISTIC(NumBounceSites, "Number of sites modified");
STATISTIC(NumBounce , "Number of bounce functions created");
namespace {
class VISIBILITY_HIDDEN IndMemRemPass : public ModulePass {
public:
static char ID; // Pass identification, replacement for typeid
IndMemRemPass() : ModulePass(&ID) {}
virtual bool runOnModule(Module &M);
};
} // end anonymous namespace
char IndMemRemPass::ID = 0;
static RegisterPass<IndMemRemPass>
X("indmemrem","Indirect Malloc and Free Removal");
bool IndMemRemPass::runOnModule(Module &M) {
// In theory, all direct calls of malloc and free should be promoted
// to intrinsics. Therefore, 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.getFunction("free")) {
if (F->isDeclaration() && F->arg_size() == 1 && !F->use_empty()) {
Function* FN = Function::Create(F->getFunctionType(),
GlobalValue::LinkOnceAnyLinkage,
"free_llvm_bounce", &M);
BasicBlock* bb = BasicBlock::Create(M.getContext(), "entry",FN);
Instruction* R = ReturnInst::Create(M.getContext(), bb);
new FreeInst(FN->arg_begin(), R);
++NumBounce;
NumBounceSites += F->getNumUses();
F->replaceAllUsesWith(FN);
changed = true;
}
}
if (Function* F = M.getFunction("malloc")) {
if (F->isDeclaration() && F->arg_size() == 1 && !F->use_empty()) {
TargetData* TD = getAnalysisIfAvailable<TargetData>();
if (TD) {
Function* FN = Function::Create(F->getFunctionType(),
GlobalValue::LinkOnceAnyLinkage,
"malloc_llvm_bounce", &M);
F->replaceAllUsesWith(FN);
FN->setDoesNotAlias(0);
BasicBlock* bb = BasicBlock::Create(M.getContext(), "entry", FN);
const Type* IntPtrTy = TD->getIntPtrType(M.getContext());
Value* c = FN->arg_begin();
if (FN->arg_begin()->getType() != IntPtrTy)
c = CastInst::CreateIntegerCast(FN->arg_begin(), IntPtrTy, false,
"c", bb);
Value* a = CallInst::CreateMalloc(bb, IntPtrTy,
Type::getInt8Ty(M.getContext()),
c, NULL, "m");
bb->getInstList().push_back(cast<Instruction>(a));
ReturnInst::Create(M.getContext(), a, bb);
++NumBounce;
NumBounceSites += F->getNumUses();
changed = true;
}
}
}
return changed;
}
ModulePass *llvm::createIndMemRemPass() {
return new IndMemRemPass();
}