forked from OSchip/llvm-project
305 lines
9.4 KiB
C++
305 lines
9.4 KiB
C++
//===- StripSymbols.cpp - Strip symbols and debug info from a module ------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// The StripSymbols transformation implements code stripping. Specifically, it
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// can delete:
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//
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// * names for virtual registers
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// * symbols for internal globals and functions
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// * debug information
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//
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// Note that this transformation makes code much less readable, so it should
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// only be used in situations where the 'strip' utility would be used, such as
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// reducing code size or making it harder to reverse engineer code.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/IPO.h"
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#include "llvm/Constants.h"
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#include "llvm/DerivedTypes.h"
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#include "llvm/Instructions.h"
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#include "llvm/LLVMContext.h"
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#include "llvm/Module.h"
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#include "llvm/Pass.h"
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#include "llvm/Analysis/DebugInfo.h"
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#include "llvm/ValueSymbolTable.h"
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#include "llvm/TypeSymbolTable.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/ADT/SmallPtrSet.h"
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using namespace llvm;
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namespace {
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class StripSymbols : public ModulePass {
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bool OnlyDebugInfo;
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public:
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static char ID; // Pass identification, replacement for typeid
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explicit StripSymbols(bool ODI = false)
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: ModulePass(&ID), OnlyDebugInfo(ODI) {}
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virtual bool runOnModule(Module &M);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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}
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};
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class StripNonDebugSymbols : public ModulePass {
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public:
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static char ID; // Pass identification, replacement for typeid
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explicit StripNonDebugSymbols()
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: ModulePass(&ID) {}
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virtual bool runOnModule(Module &M);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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}
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};
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class StripDebugDeclare : public ModulePass {
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public:
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static char ID; // Pass identification, replacement for typeid
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explicit StripDebugDeclare()
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: ModulePass(&ID) {}
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virtual bool runOnModule(Module &M);
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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}
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};
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}
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char StripSymbols::ID = 0;
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static RegisterPass<StripSymbols>
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X("strip", "Strip all symbols from a module");
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ModulePass *llvm::createStripSymbolsPass(bool OnlyDebugInfo) {
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return new StripSymbols(OnlyDebugInfo);
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}
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char StripNonDebugSymbols::ID = 0;
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static RegisterPass<StripNonDebugSymbols>
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Y("strip-nondebug", "Strip all symbols, except dbg symbols, from a module");
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ModulePass *llvm::createStripNonDebugSymbolsPass() {
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return new StripNonDebugSymbols();
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}
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char StripDebugDeclare::ID = 0;
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static RegisterPass<StripDebugDeclare>
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Z("strip-debug-declare", "Strip all llvm.dbg.declare intrinsics");
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ModulePass *llvm::createStripDebugDeclarePass() {
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return new StripDebugDeclare();
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}
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/// OnlyUsedBy - Return true if V is only used by Usr.
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static bool OnlyUsedBy(Value *V, Value *Usr) {
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for(Value::use_iterator I = V->use_begin(), E = V->use_end(); I != E; ++I) {
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User *U = *I;
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if (U != Usr)
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return false;
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}
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return true;
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}
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static void RemoveDeadConstant(Constant *C) {
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assert(C->use_empty() && "Constant is not dead!");
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SmallPtrSet<Constant*, 4> Operands;
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for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
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if (isa<DerivedType>(C->getOperand(i)->getType()) &&
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OnlyUsedBy(C->getOperand(i), C))
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Operands.insert(cast<Constant>(C->getOperand(i)));
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if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
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if (!GV->hasLocalLinkage()) return; // Don't delete non static globals.
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GV->eraseFromParent();
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}
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else if (!isa<Function>(C))
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if (isa<CompositeType>(C->getType()))
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C->destroyConstant();
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// If the constant referenced anything, see if we can delete it as well.
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for (SmallPtrSet<Constant*, 4>::iterator OI = Operands.begin(),
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OE = Operands.end(); OI != OE; ++OI)
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RemoveDeadConstant(*OI);
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}
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// Strip the symbol table of its names.
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//
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static void StripSymtab(ValueSymbolTable &ST, bool PreserveDbgInfo) {
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for (ValueSymbolTable::iterator VI = ST.begin(), VE = ST.end(); VI != VE; ) {
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Value *V = VI->getValue();
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++VI;
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if (!isa<GlobalValue>(V) || cast<GlobalValue>(V)->hasLocalLinkage()) {
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if (!PreserveDbgInfo || !V->getName().startswith("llvm.dbg"))
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// Set name to "", removing from symbol table!
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V->setName("");
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}
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}
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}
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// Strip the symbol table of its names.
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static void StripTypeSymtab(TypeSymbolTable &ST, bool PreserveDbgInfo) {
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for (TypeSymbolTable::iterator TI = ST.begin(), E = ST.end(); TI != E; ) {
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if (PreserveDbgInfo && strncmp(TI->first.c_str(), "llvm.dbg", 8) == 0)
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++TI;
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else
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ST.remove(TI++);
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}
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}
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/// Find values that are marked as llvm.used.
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static void findUsedValues(GlobalVariable *LLVMUsed,
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SmallPtrSet<const GlobalValue*, 8> &UsedValues) {
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if (LLVMUsed == 0) return;
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UsedValues.insert(LLVMUsed);
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ConstantArray *Inits = dyn_cast<ConstantArray>(LLVMUsed->getInitializer());
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if (Inits == 0) return;
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for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
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if (GlobalValue *GV =
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dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
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UsedValues.insert(GV);
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}
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/// StripSymbolNames - Strip symbol names.
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static bool StripSymbolNames(Module &M, bool PreserveDbgInfo) {
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SmallPtrSet<const GlobalValue*, 8> llvmUsedValues;
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findUsedValues(M.getGlobalVariable("llvm.used"), llvmUsedValues);
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findUsedValues(M.getGlobalVariable("llvm.compiler.used"), llvmUsedValues);
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for (Module::global_iterator I = M.global_begin(), E = M.global_end();
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I != E; ++I) {
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if (I->hasLocalLinkage() && llvmUsedValues.count(I) == 0)
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if (!PreserveDbgInfo || !I->getName().startswith("llvm.dbg"))
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I->setName(""); // Internal symbols can't participate in linkage
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}
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for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
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if (I->hasLocalLinkage() && llvmUsedValues.count(I) == 0)
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if (!PreserveDbgInfo || !I->getName().startswith("llvm.dbg"))
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I->setName(""); // Internal symbols can't participate in linkage
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StripSymtab(I->getValueSymbolTable(), PreserveDbgInfo);
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}
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// Remove all names from types.
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StripTypeSymtab(M.getTypeSymbolTable(), PreserveDbgInfo);
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return true;
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}
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// StripDebugInfo - Strip debug info in the module if it exists.
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// To do this, we remove llvm.dbg.func.start, llvm.dbg.stoppoint, and
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// llvm.dbg.region.end calls, and any globals they point to if now dead.
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static bool StripDebugInfo(Module &M) {
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// Remove all of the calls to the debugger intrinsics, and remove them from
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// the module.
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Function *FuncStart = M.getFunction("llvm.dbg.func.start");
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Function *StopPoint = M.getFunction("llvm.dbg.stoppoint");
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Function *RegionStart = M.getFunction("llvm.dbg.region.start");
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Function *RegionEnd = M.getFunction("llvm.dbg.region.end");
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Function *Declare = M.getFunction("llvm.dbg.declare");
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if (FuncStart) {
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while (!FuncStart->use_empty()) {
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CallInst *CI = cast<CallInst>(FuncStart->use_back());
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CI->eraseFromParent();
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}
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FuncStart->eraseFromParent();
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}
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if (StopPoint) {
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while (!StopPoint->use_empty()) {
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CallInst *CI = cast<CallInst>(StopPoint->use_back());
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CI->eraseFromParent();
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}
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StopPoint->eraseFromParent();
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}
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if (RegionStart) {
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while (!RegionStart->use_empty()) {
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CallInst *CI = cast<CallInst>(RegionStart->use_back());
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CI->eraseFromParent();
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}
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RegionStart->eraseFromParent();
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}
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if (RegionEnd) {
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while (!RegionEnd->use_empty()) {
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CallInst *CI = cast<CallInst>(RegionEnd->use_back());
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CI->eraseFromParent();
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}
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RegionEnd->eraseFromParent();
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}
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if (Declare) {
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while (!Declare->use_empty()) {
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CallInst *CI = cast<CallInst>(Declare->use_back());
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CI->eraseFromParent();
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}
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Declare->eraseFromParent();
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}
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NamedMDNode *NMD = M.getNamedMetadata("llvm.dbg.gv");
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if (NMD)
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NMD->eraseFromParent();
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return true;
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}
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bool StripSymbols::runOnModule(Module &M) {
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bool Changed = false;
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Changed |= StripDebugInfo(M);
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if (!OnlyDebugInfo)
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Changed |= StripSymbolNames(M, false);
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return Changed;
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}
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bool StripNonDebugSymbols::runOnModule(Module &M) {
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return StripSymbolNames(M, true);
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}
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bool StripDebugDeclare::runOnModule(Module &M) {
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Function *Declare = M.getFunction("llvm.dbg.declare");
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std::vector<Constant*> DeadConstants;
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if (Declare) {
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while (!Declare->use_empty()) {
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CallInst *CI = cast<CallInst>(Declare->use_back());
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Value *Arg1 = CI->getOperand(1);
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Value *Arg2 = CI->getOperand(2);
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assert(CI->use_empty() && "llvm.dbg intrinsic should have void result");
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CI->eraseFromParent();
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if (Arg1->use_empty()) {
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if (Constant *C = dyn_cast<Constant>(Arg1))
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DeadConstants.push_back(C);
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else
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RecursivelyDeleteTriviallyDeadInstructions(Arg1);
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}
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if (Arg2->use_empty())
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if (Constant *C = dyn_cast<Constant>(Arg2))
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DeadConstants.push_back(C);
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}
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Declare->eraseFromParent();
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}
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while (!DeadConstants.empty()) {
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Constant *C = DeadConstants.back();
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DeadConstants.pop_back();
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if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
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if (GV->hasLocalLinkage())
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RemoveDeadConstant(GV);
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} else
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RemoveDeadConstant(C);
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}
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return true;
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}
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