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//===- 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/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/Pass.h"
#include "llvm/ValueSymbolTable.h"
#include "llvm/TypeSymbolTable.h"
#include "llvm/Support/Compiler.h"
using namespace llvm;
namespace {
class VISIBILITY_HIDDEN StripSymbols : public ModulePass {
bool OnlyDebugInfo;
public:
static const int ID; // Pass identifcation, replacement for typeid
StripSymbols(bool ODI = false)
: ModulePass((intptr_t)&ID), OnlyDebugInfo(ODI) {}
virtual bool runOnModule(Module &M);
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
}
};
const int StripSymbols::ID = 0;
RegisterPass<StripSymbols> X("strip", "Strip all symbols from a module");
}
ModulePass *llvm::createStripSymbolsPass(bool OnlyDebugInfo) {
return new StripSymbols(OnlyDebugInfo);
}
static void RemoveDeadConstant(Constant *C) {
assert(C->use_empty() && "Constant is not dead!");
std::vector<Constant*> Operands;
for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
if (isa<DerivedType>(C->getOperand(i)->getType()) &&
C->getOperand(i)->hasOneUse())
Operands.push_back(C->getOperand(i));
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
if (!GV->hasInternalLinkage()) return; // Don't delete non static globals.
GV->eraseFromParent();
}
else if (!isa<Function>(C))
C->destroyConstant();
// If the constant referenced anything, see if we can delete it as well.
while (!Operands.empty()) {
RemoveDeadConstant(Operands.back());
Operands.pop_back();
}
}
// Strip the symbol table of its names.
//
static void StripSymtab(ValueSymbolTable &ST) {
for (ValueSymbolTable::iterator VI = ST.begin(), VE = ST.end(); VI != VE; ) {
Value *V = VI->getValue();
++VI;
if (!isa<GlobalValue>(V) || cast<GlobalValue>(V)->hasInternalLinkage()) {
// Set name to "", removing from symbol table!
V->setName("");
}
}
}
// Strip the symbol table of its names.
static void StripTypeSymtab(TypeSymbolTable &ST) {
for (TypeSymbolTable::iterator TI = ST.begin(), E = ST.end(); TI != E; )
ST.remove(TI++);
}
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::global_iterator I = M.global_begin(), E = M.global_end();
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
StripSymtab(I->getValueSymbolTable());
}
// Remove all names from types.
StripTypeSymtab(M.getTypeSymbolTable());
}
// Strip debug info in the module if it exists. To do this, we remove
// llvm.dbg.func.start, llvm.dbg.stoppoint, and llvm.dbg.region.end calls, and
// any globals they point to if now dead.
Function *FuncStart = M.getFunction("llvm.dbg.func.start");
Function *StopPoint = M.getFunction("llvm.dbg.stoppoint");
Function *RegionStart = M.getFunction("llvm.dbg.region.start");
Function *RegionEnd = M.getFunction("llvm.dbg.region.end");
Function *Declare = M.getFunction("llvm.dbg.declare");
if (!FuncStart && !StopPoint && !RegionStart && !RegionEnd && !Declare)
return true;
std::vector<GlobalVariable*> DeadGlobals;
// Remove all of the calls to the debugger intrinsics, and remove them from
// the module.
if (FuncStart) {
while (!FuncStart->use_empty()) {
CallInst *CI = cast<CallInst>(FuncStart->use_back());
Value *Arg = CI->getOperand(1);
assert(CI->use_empty() && "llvm.dbg intrinsic should have void result");
CI->eraseFromParent();
if (Arg->use_empty())
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Arg))
DeadGlobals.push_back(GV);
}
FuncStart->eraseFromParent();
}
if (StopPoint) {
while (!StopPoint->use_empty()) {
CallInst *CI = cast<CallInst>(StopPoint->use_back());
Value *Arg = CI->getOperand(3);
assert(CI->use_empty() && "llvm.dbg intrinsic should have void result");
CI->eraseFromParent();
if (Arg->use_empty())
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Arg))
DeadGlobals.push_back(GV);
}
StopPoint->eraseFromParent();
}
if (RegionStart) {
while (!RegionStart->use_empty()) {
CallInst *CI = cast<CallInst>(RegionStart->use_back());
Value *Arg = CI->getOperand(1);
assert(CI->use_empty() && "llvm.dbg intrinsic should have void result");
CI->eraseFromParent();
if (Arg->use_empty())
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Arg))
DeadGlobals.push_back(GV);
}
RegionStart->eraseFromParent();
}
if (RegionEnd) {
while (!RegionEnd->use_empty()) {
CallInst *CI = cast<CallInst>(RegionEnd->use_back());
Value *Arg = CI->getOperand(1);
assert(CI->use_empty() && "llvm.dbg intrinsic should have void result");
CI->eraseFromParent();
if (Arg->use_empty())
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Arg))
DeadGlobals.push_back(GV);
}
RegionEnd->eraseFromParent();
}
if (Declare) {
while (!Declare->use_empty()) {
CallInst *CI = cast<CallInst>(Declare->use_back());
Value *Arg = CI->getOperand(2);
assert(CI->use_empty() && "llvm.dbg intrinsic should have void result");
CI->eraseFromParent();
if (Arg->use_empty())
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Arg))
DeadGlobals.push_back(GV);
}
Declare->eraseFromParent();
}
// Finally, delete any internal globals that were only used by the debugger
// intrinsics.
while (!DeadGlobals.empty()) {
GlobalVariable *GV = DeadGlobals.back();
DeadGlobals.pop_back();
if (GV->hasInternalLinkage())
RemoveDeadConstant(GV);
}
return true;
}
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