Add a pass that renames everything with metasyntatic names. This works well after using bugpoint to reduce the confusion presented by the original names, which no longer mean what they used to.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163592 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Utils/MetaRenamer.cpp

@@ -0,0 +1,132 @@
+//===- MetaRenamer.cpp - Rename everything with metasyntatic names --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass renames everything with metasyntatic names. The intent is to use
+// this pass after bugpoint reduction to conceal the nature of the original
+// program.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Function.h"
+#include "llvm/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Type.h"
+#include "llvm/TypeFinder.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallString.h"
+
+using namespace llvm;
+
+namespace {
+
+  // This PRNG is from the ISO C spec. It is intentionally simple and
+  // unsuitable for cryptographic use. We're just looking for enough
+  // variety to surprise and delight users.
+  struct PRNG {
+    unsigned long next;
+
+    void srand(unsigned int seed) {
+      next = seed;
+    }
+
+    int rand(void) {
+      next = next * 1103515245 + 12345;
+      return (unsigned int)(next / 65536) % 32768;
+    }
+  };
+
+  struct MetaRenamer : public ModulePass {
+    static char ID; // Pass identification, replacement for typeid
+    MetaRenamer() : ModulePass(ID) {
+      initializeMetaRenamerPass(*PassRegistry::getPassRegistry());
+    }
+
+    void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.setPreservesAll();
+    }
+
+    bool runOnModule(Module &M) {
+      static const char *metaNames[] = {
+        // See http://en.wikipedia.org/wiki/Metasyntactic_variable
+        "foo", "bar", "baz", "quux", "barney", "snork", "zot", "blam", "hoge",
+        "wibble", "wobble", "widget", "wombat", "ham", "eggs", "pluto", "spam"
+      };
+
+      // Seed our PRNG with simple additive sum of ModuleID. We're looking to
+      // simply avoid always having the same function names, and we need to
+      // remain deterministic.
+      unsigned int randSeed = 0;
+      for (std::string::const_iterator I = M.getModuleIdentifier().begin(),
+           E = M.getModuleIdentifier().end(); I != E; ++I)
+        randSeed += *I;
+
+      PRNG prng;
+      prng.srand(randSeed);
+
+      // Rename all aliases
+      for (Module::alias_iterator AI = M.alias_begin(), AE = M.alias_end();
+           AI != AE; ++AI)
+        AI->setName("alias");
+
+      // Rename all global variables
+      for (Module::global_iterator GI = M.global_begin(), GE = M.global_end();
+           GI != GE; ++GI)
+        GI->setName("global");
+
+      // Rename all struct types
+      TypeFinder StructTypes;
+      StructTypes.run(M, true);
+      for (unsigned i = 0, e = StructTypes.size(); i != e; ++i) {
+        StructType *STy = StructTypes[i];
+        if (STy->isLiteral() || STy->getName().empty()) continue;
+
+        SmallString<128> NameStorage;
+        STy->setName((Twine("struct.") + metaNames[prng.rand() %
+                     array_lengthof(metaNames)]).toStringRef(NameStorage));
+      }
+
+      // Rename all functions
+      for (Module::iterator FI = M.begin(), FE = M.end();
+           FI != FE; ++FI) {
+        FI->setName(metaNames[prng.rand() % array_lengthof(metaNames)]);
+        runOnFunction(*FI);
+      }
+      return true;
+    }
+
+    bool runOnFunction(Function &F) {
+      for (Function::arg_iterator AI = F.arg_begin(), AE = F.arg_end();
+           AI != AE; ++AI)
+        if (!AI->getType()->isVoidTy())
+          AI->setName("arg");
+
+      for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
+        BB->setName("bb");
+
+        for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
+          if (!I->getType()->isVoidTy())
+            I->setName("tmp");
+      }
+      return true;
+    }
+  };
+}
+
+char MetaRenamer::ID = 0;
+INITIALIZE_PASS(MetaRenamer, "metarenamer", 
+                "Assign new names to everything", false, false)
+//===----------------------------------------------------------------------===//
+//
+// MetaRenamer - Rename everything with metasyntactic names.
+//
+ModulePass *llvm::createMetaRenamerPass() {
+  return new MetaRenamer();
+}