//
// 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 is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
-// This file implements stripping symbols out of symbol tables.
+// The StripSymbols transformation implements code stripping. Specifically, it
+// can delete:
+//
+// * names for virtual registers
+// * symbols for internal globals and functions
+// * debug information
//
-// 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).
+// Note that this transformation 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 or making it harder to reverse engineer code.
//
//===----------------------------------------------------------------------===//
#include "llvm/ValueSymbolTable.h"
#include "llvm/TypeSymbolTable.h"
#include "llvm/Support/Compiler.h"
+#include "llvm/ADT/SmallPtrSet.h"
using namespace llvm;
namespace {
class VISIBILITY_HIDDEN StripSymbols : public ModulePass {
bool OnlyDebugInfo;
public:
- static char ID; // Pass identifcation, replacement for typeid
- StripSymbols(bool ODI = false)
+ static char ID; // Pass identification, replacement for typeid
+ explicit StripSymbols(bool ODI = false)
: ModulePass((intptr_t)&ID), OnlyDebugInfo(ODI) {}
virtual bool runOnModule(Module &M);
AU.setPreservesAll();
}
};
-
- char StripSymbols::ID = 0;
- RegisterPass<StripSymbols> X("strip", "Strip all symbols from a module");
}
+char StripSymbols::ID = 0;
+static RegisterPass<StripSymbols>
+X("strip", "Strip all symbols from a module");
+
ModulePass *llvm::createStripSymbolsPass(bool OnlyDebugInfo) {
return new StripSymbols(OnlyDebugInfo);
}
// If we're not just stripping debug info, strip all symbols from the
// functions and the names from any internal globals.
if (!OnlyDebugInfo) {
+ SmallPtrSet<const GlobalValue*, 8> llvmUsedValues;
+ if (GlobalVariable *LLVMUsed = M.getGlobalVariable("llvm.used")) {
+ llvmUsedValues.insert(LLVMUsed);
+ // Collect values that are preserved as per explicit request.
+ // llvm.used is used to list these values.
+ if (ConstantArray *Inits =
+ dyn_cast<ConstantArray>(LLVMUsed->getInitializer())) {
+ for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i) {
+ if (GlobalValue *GV = dyn_cast<GlobalValue>(Inits->getOperand(i)))
+ llvmUsedValues.insert(GV);
+ else if (ConstantExpr *CE =
+ dyn_cast<ConstantExpr>(Inits->getOperand(i)))
+ if (CE->getOpcode() == Instruction::BitCast)
+ if (GlobalValue *GV = dyn_cast<GlobalValue>(CE->getOperand(0)))
+ llvmUsedValues.insert(GV);
+ }
+ }
+ }
+
for (Module::global_iterator I = M.global_begin(), E = M.global_end();
- I != E; ++I)
- if (I->hasInternalLinkage())
+ I != E; ++I) {
+ if (I->hasInternalLinkage() && llvmUsedValues.count(I) == 0)
I->setName(""); // Internal symbols can't participate in linkage
+ }
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
- if (I->hasInternalLinkage())
+ if (I->hasInternalLinkage() && llvmUsedValues.count(I) == 0)
I->setName(""); // Internal symbols can't participate in linkage
StripSymtab(I->getValueSymbolTable());
}