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3e15bf33e0
Due to darwin gcc bug, one version of darwin linker coalesces static const int, which defauts PassID based pass identification. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36652 91177308-0d34-0410-b5e6-96231b3b80d8
90 lines
3.3 KiB
C++
90 lines
3.3 KiB
C++
//===-- IndMemRemoval.cpp - Remove indirect allocations and frees ----------===//
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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 pass finds places where memory allocation functions may escape into
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// indirect land. Some transforms are much easier (aka possible) only if free
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// or malloc are not called indirectly.
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// Thus find places where the address of memory functions are taken and construct
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// bounce functions with direct calls of those functions.
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//
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//===----------------------------------------------------------------------===//
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#define DEBUG_TYPE "indmemrem"
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#include "llvm/Transforms/IPO.h"
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#include "llvm/Pass.h"
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#include "llvm/Module.h"
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#include "llvm/Instructions.h"
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#include "llvm/Type.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Support/Compiler.h"
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using namespace llvm;
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STATISTIC(NumBounceSites, "Number of sites modified");
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STATISTIC(NumBounce , "Number of bounce functions created");
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namespace {
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class VISIBILITY_HIDDEN IndMemRemPass : public ModulePass {
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public:
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static const char ID; // Pass identifcation, replacement for typeid
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IndMemRemPass() : ModulePass((intptr_t)&ID) {}
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virtual bool runOnModule(Module &M);
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};
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const char IndMemRemPass::ID = 0;
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RegisterPass<IndMemRemPass> X("indmemrem","Indirect Malloc and Free Removal");
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} // end anonymous namespace
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bool IndMemRemPass::runOnModule(Module &M) {
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//in Theory, all direct calls of malloc and free should be promoted
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//to intrinsics. Therefor, this goes through and finds where the
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//address of free or malloc are taken and replaces those with bounce
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//functions, ensuring that all malloc and free that might happen
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//happen through intrinsics.
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bool changed = false;
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if (Function* F = M.getFunction("free")) {
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assert(F->isDeclaration() && "free not external?");
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if (!F->use_empty()) {
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Function* FN = new Function(F->getFunctionType(),
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GlobalValue::LinkOnceLinkage,
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"free_llvm_bounce", &M);
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BasicBlock* bb = new BasicBlock("entry",FN);
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Instruction* R = new ReturnInst(bb);
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new FreeInst(FN->arg_begin(), R);
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++NumBounce;
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NumBounceSites += F->getNumUses();
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F->replaceAllUsesWith(FN);
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changed = true;
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}
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}
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if (Function* F = M.getFunction("malloc")) {
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assert(F->isDeclaration() && "malloc not external?");
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if (!F->use_empty()) {
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Function* FN = new Function(F->getFunctionType(),
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GlobalValue::LinkOnceLinkage,
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"malloc_llvm_bounce", &M);
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BasicBlock* bb = new BasicBlock("entry",FN);
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Instruction* c = CastInst::createIntegerCast(
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FN->arg_begin(), Type::Int32Ty, false, "c", bb);
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Instruction* a = new MallocInst(Type::Int8Ty, c, "m", bb);
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new ReturnInst(a, bb);
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++NumBounce;
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NumBounceSites += F->getNumUses();
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F->replaceAllUsesWith(FN);
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changed = true;
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}
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}
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return changed;
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}
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ModulePass *llvm::createIndMemRemPass() {
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return new IndMemRemPass();
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}
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