Initial reimplementation of the -strip pass, with a stub for implementing

-S


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@18440 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/StripSymbols.cpp

@@ -0,0 +1,68 @@
+//===- StripSymbols.cpp - Strip symbols and debug info from a module ------===//
+// 
+//                     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 file implements stripping symbols out of symbol tables.
+//
+// Specifically, this allows you to strip all of the symbols out of:
+//   * All functions in a module
+//   * All non-essential symbols in a module (all function symbols + all module
+//     scope symbols)
+//   * Debug information.
+//
+// Notice that:
+//   * This pass makes code much less readable, so it should only be used in
+//     situations where the 'strip' utility would be used (such as reducing 
+//     code size, and making it harder to reverse engineer code).
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/IPO.h"
+#include "llvm/Module.h"
+#include "llvm/SymbolTable.h"
+#include "llvm/Pass.h"
+using namespace llvm;
+
+namespace {
+  class StripSymbols : public ModulePass {
+    bool OnlyDebugInfo;
+  public:
+    StripSymbols(bool ODI = false) : OnlyDebugInfo(ODI) {}
+
+    virtual bool runOnModule(Module &M);
+
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.setPreservesAll();
+    }
+  };
+  RegisterOpt<StripSymbols> X("strip", "Strip all symbols from a module");
+}
+
+ModulePass *llvm::createStripSymbolsPass(bool OnlyDebugInfo) {
+  return new StripSymbols(OnlyDebugInfo);
+}
+
+
+bool StripSymbols::runOnModule(Module &M) {
+  // If we're not just stripping debug info, strip all symbols from the
+  // functions and the names from any internal globals.
+  if (!OnlyDebugInfo) {
+    for (Module::giterator I = M.gbegin(), E = M.gend(); I != E; ++I)
+      if (I->hasInternalLinkage())
+        I->setName("");     // Internal symbols can't participate in linkage
+
+    for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
+      if (I->hasInternalLinkage())
+        I->setName("");     // Internal symbols can't participate in linkage
+      I->getSymbolTable().strip();
+    }
+  }
+
+  // FIXME: implement stripping of debug info.
+  return true; 
+}