151 lines
4.3 KiB
C++
151 lines
4.3 KiB
C++
//===- MetaRenamer.cpp - Rename everything with metasyntatic names --------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This pass renames everything with metasyntatic names. The intent is to use
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// this pass after bugpoint reduction to conceal the nature of the original
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// program.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/IPO.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/IR/DerivedTypes.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/Type.h"
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#include "llvm/IR/TypeFinder.h"
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#include "llvm/Pass.h"
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using namespace llvm;
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namespace {
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// This PRNG is from the ISO C spec. It is intentionally simple and
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// unsuitable for cryptographic use. We're just looking for enough
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// variety to surprise and delight users.
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struct PRNG {
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unsigned long next;
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void srand(unsigned int seed) {
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next = seed;
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}
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int rand() {
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next = next * 1103515245 + 12345;
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return (unsigned int)(next / 65536) % 32768;
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}
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};
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static const char *const metaNames[] = {
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// See http://en.wikipedia.org/wiki/Metasyntactic_variable
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"foo", "bar", "baz", "quux", "barney", "snork", "zot", "blam", "hoge",
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"wibble", "wobble", "widget", "wombat", "ham", "eggs", "pluto", "spam"
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};
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struct Renamer {
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Renamer(unsigned int seed) {
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prng.srand(seed);
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}
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const char *newName() {
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return metaNames[prng.rand() % array_lengthof(metaNames)];
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}
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PRNG prng;
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};
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struct MetaRenamer : public ModulePass {
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static char ID; // Pass identification, replacement for typeid
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MetaRenamer() : ModulePass(ID) {
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initializeMetaRenamerPass(*PassRegistry::getPassRegistry());
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}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesAll();
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}
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bool runOnModule(Module &M) override {
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// Seed our PRNG with simple additive sum of ModuleID. We're looking to
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// simply avoid always having the same function names, and we need to
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// remain deterministic.
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unsigned int randSeed = 0;
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for (auto C : M.getModuleIdentifier())
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randSeed += C;
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Renamer renamer(randSeed);
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// Rename all aliases
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for (auto AI = M.alias_begin(), AE = M.alias_end(); AI != AE; ++AI) {
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StringRef Name = AI->getName();
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if (Name.startswith("llvm.") || (!Name.empty() && Name[0] == 1))
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continue;
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AI->setName("alias");
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}
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// Rename all global variables
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for (auto GI = M.global_begin(), GE = M.global_end(); GI != GE; ++GI) {
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StringRef Name = GI->getName();
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if (Name.startswith("llvm.") || (!Name.empty() && Name[0] == 1))
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continue;
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GI->setName("global");
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}
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// Rename all struct types
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TypeFinder StructTypes;
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StructTypes.run(M, true);
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for (StructType *STy : StructTypes) {
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if (STy->isLiteral() || STy->getName().empty()) continue;
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SmallString<128> NameStorage;
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STy->setName((Twine("struct.") +
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renamer.newName()).toStringRef(NameStorage));
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}
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// Rename all functions
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for (auto &F : M) {
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StringRef Name = F.getName();
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if (Name.startswith("llvm.") || (!Name.empty() && Name[0] == 1))
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continue;
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F.setName(renamer.newName());
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runOnFunction(F);
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}
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return true;
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}
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bool runOnFunction(Function &F) {
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for (auto AI = F.arg_begin(), AE = F.arg_end(); AI != AE; ++AI)
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if (!AI->getType()->isVoidTy())
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AI->setName("arg");
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for (auto &BB : F) {
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BB.setName("bb");
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for (auto &I : BB)
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if (!I.getType()->isVoidTy())
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I.setName("tmp");
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}
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return true;
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}
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};
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}
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char MetaRenamer::ID = 0;
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INITIALIZE_PASS(MetaRenamer, "metarenamer",
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"Assign new names to everything", false, false)
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//===----------------------------------------------------------------------===//
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//
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// MetaRenamer - Rename everything with metasyntactic names.
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//
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ModulePass *llvm::createMetaRenamerPass() {
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return new MetaRenamer();
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}
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