1 //===- SymbolStripping.cpp - Strip symbols for functions and modules ------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements stripping symbols out of symbol tables.
12 // Specifically, this allows you to strip all of the symbols out of:
13 // * All functions in a module
14 // * All non-essential symbols in a module (all function symbols + all module
18 // * This pass makes code much less readable, so it should only be used in
19 // situations where the 'strip' utility would be used (such as reducing
20 // code size, and making it harder to reverse engineer code).
22 //===----------------------------------------------------------------------===//
24 #include "llvm/Transforms/Scalar.h"
25 #include "llvm/Module.h"
26 #include "llvm/SymbolTable.h"
27 #include "llvm/Pass.h"
30 static bool StripSymbolTable(SymbolTable &SymTab) {
31 bool RemovedSymbol = false;
33 for (SymbolTable::iterator I = SymTab.begin(); I != SymTab.end();) {
34 // Removing items from the plane can cause the plane itself to get deleted.
35 // If this happens, make sure we incremented our plane iterator already!
36 std::map<const std::string, Value *> &Plane = (I++)->second;
38 SymbolTable::type_iterator B = Plane.begin(), Bend = Plane.end();
39 while (B != Bend) { // Found nonempty type plane!
42 if (isa<Constant>(V) || isa<Type>(V)) {
43 SymTab.type_remove(B++);
47 if (!isa<GlobalValue>(V) || cast<GlobalValue>(V)->hasInternalLinkage()){
48 // Set name to "", removing from symbol table!
49 V->setName("", &SymTab);
60 struct SymbolStripping : public FunctionPass {
61 virtual bool runOnFunction(Function &F) {
62 return StripSymbolTable(F.getSymbolTable());
64 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
68 RegisterOpt<SymbolStripping> X("strip", "Strip symbols from functions");
70 struct FullSymbolStripping : public SymbolStripping {
71 virtual bool doInitialization(Module &M) {
72 return StripSymbolTable(M.getSymbolTable());
75 RegisterOpt<FullSymbolStripping> Y("mstrip",
76 "Strip symbols from module and functions");
79 Pass *llvm::createSymbolStrippingPass() {
80 return new SymbolStripping();
83 Pass *llvm::createFullSymbolStrippingPass() {
84 return new FullSymbolStripping();