| //===-- 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 <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 = |
| CastInst::createInferredCast(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(); |
| } |