lib/Transforms/IPO/StripSymbols.cpp - platform/external/llvm - Git at Google

 //===- StripSymbols.cpp - Strip symbols and debug info from a module ------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // The StripSymbols transformation implements code stripping. Specifically, it
 // can delete:
 //
 //   * names for virtual registers
 //   * symbols for internal globals and functions
 //   * debug information
 //
 // 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/Transforms/IPO.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/Constants.h"
 #include "llvm/DebugInfo.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/Instructions.h"
 #include "llvm/Module.h"
 #include "llvm/Pass.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include "llvm/TypeFinder.h"
 #include "llvm/ValueSymbolTable.h"
 using namespace llvm;

 namespace {
   class StripSymbols : public ModulePass {
     bool OnlyDebugInfo;
   public:
     static char ID; // Pass identification, replacement for typeid
     explicit StripSymbols(bool ODI = false)
       : ModulePass(ID), OnlyDebugInfo(ODI) {
         initializeStripSymbolsPass(*PassRegistry::getPassRegistry());
       }

     virtual bool runOnModule(Module &M);

     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.setPreservesAll();
     }
   };

   class StripNonDebugSymbols : public ModulePass {
   public:
     static char ID; // Pass identification, replacement for typeid
     explicit StripNonDebugSymbols()
       : ModulePass(ID) {
         initializeStripNonDebugSymbolsPass(*PassRegistry::getPassRegistry());
       }

     virtual bool runOnModule(Module &M);

     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.setPreservesAll();
     }
   };

   class StripDebugDeclare : public ModulePass {
   public:
     static char ID; // Pass identification, replacement for typeid
     explicit StripDebugDeclare()
       : ModulePass(ID) {
         initializeStripDebugDeclarePass(*PassRegistry::getPassRegistry());
       }

     virtual bool runOnModule(Module &M);

     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.setPreservesAll();
     }
   };

   class StripDeadDebugInfo : public ModulePass {
   public:
     static char ID; // Pass identification, replacement for typeid
     explicit StripDeadDebugInfo()
       : ModulePass(ID) {
         initializeStripDeadDebugInfoPass(*PassRegistry::getPassRegistry());
       }

     virtual bool runOnModule(Module &M);

     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.setPreservesAll();
     }
   };
 }

 char StripSymbols::ID = 0;
 INITIALIZE_PASS(StripSymbols, "strip",
                 "Strip all symbols from a module", false, false)

 ModulePass *llvm::createStripSymbolsPass(bool OnlyDebugInfo) {
   return new StripSymbols(OnlyDebugInfo);
 }

 char StripNonDebugSymbols::ID = 0;
 INITIALIZE_PASS(StripNonDebugSymbols, "strip-nondebug",
                 "Strip all symbols, except dbg symbols, from a module",
                 false, false)

 ModulePass *llvm::createStripNonDebugSymbolsPass() {
   return new StripNonDebugSymbols();
 }

 char StripDebugDeclare::ID = 0;
 INITIALIZE_PASS(StripDebugDeclare, "strip-debug-declare",
                 "Strip all llvm.dbg.declare intrinsics", false, false)

 ModulePass *llvm::createStripDebugDeclarePass() {
   return new StripDebugDeclare();
 }

 char StripDeadDebugInfo::ID = 0;
 INITIALIZE_PASS(StripDeadDebugInfo, "strip-dead-debug-info",
                 "Strip debug info for unused symbols", false, false)

 ModulePass *llvm::createStripDeadDebugInfoPass() {
   return new StripDeadDebugInfo();
 }

 /// OnlyUsedBy - Return true if V is only used by Usr.
 static bool OnlyUsedBy(Value *V, Value *Usr) {
   for(Value::use_iterator I = V->use_begin(), E = V->use_end(); I != E; ++I) {
     User *U = *I;
     if (U != Usr)
       return false;
   }
   return true;
 }

 static void RemoveDeadConstant(Constant *C) {
   assert(C->use_empty() && "Constant is not dead!");
   SmallPtrSet<Constant*, 4> Operands;
   for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
     if (OnlyUsedBy(C->getOperand(i), C))
       Operands.insert(cast<Constant>(C->getOperand(i)));
   if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
     if (!GV->hasLocalLinkage()) return;   // Don't delete non static globals.
     GV->eraseFromParent();
   }
   else if (!isa<Function>(C))
     if (isa<CompositeType>(C->getType()))
       C->destroyConstant();

   // If the constant referenced anything, see if we can delete it as well.
   for (SmallPtrSet<Constant*, 4>::iterator OI = Operands.begin(),
          OE = Operands.end(); OI != OE; ++OI)
     RemoveDeadConstant(*OI);
 }

 // Strip the symbol table of its names.
 //
 static void StripSymtab(ValueSymbolTable &ST, bool PreserveDbgInfo) {
   for (ValueSymbolTable::iterator VI = ST.begin(), VE = ST.end(); VI != VE; ) {
     Value *V = VI->getValue();
     ++VI;
     if (!isa<GlobalValue>(V) || cast<GlobalValue>(V)->hasLocalLinkage()) {
       if (!PreserveDbgInfo || !V->getName().startswith("llvm.dbg"))
         // Set name to "", removing from symbol table!
         V->setName("");
     }
   }
 }

 // Strip any named types of their names.
 static void StripTypeNames(Module &M, bool PreserveDbgInfo) {
   TypeFinder StructTypes;
   StructTypes.run(M, false);

   for (unsigned i = 0, e = StructTypes.size(); i != e; ++i) {
     StructType *STy = StructTypes[i];
     if (STy->isLiteral() || STy->getName().empty()) continue;

     if (PreserveDbgInfo && STy->getName().startswith("llvm.dbg"))
       continue;

     STy->setName("");
   }
 }

 /// Find values that are marked as llvm.used.
 static void findUsedValues(GlobalVariable *LLVMUsed,
                            SmallPtrSet<const GlobalValue*, 8> &UsedValues) {
   if (LLVMUsed == 0) return;
   UsedValues.insert(LLVMUsed);

   ConstantArray *Inits = dyn_cast<ConstantArray>(LLVMUsed->getInitializer());
   if (Inits == 0) return;

   for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
     if (GlobalValue *GV =
           dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
       UsedValues.insert(GV);
 }

 /// StripSymbolNames - Strip symbol names.
 static bool StripSymbolNames(Module &M, bool PreserveDbgInfo) {

   SmallPtrSet<const GlobalValue*, 8> llvmUsedValues;
   findUsedValues(M.getGlobalVariable("llvm.used"), llvmUsedValues);
   findUsedValues(M.getGlobalVariable("llvm.compiler.used"), llvmUsedValues);

   for (Module::global_iterator I = M.global_begin(), E = M.global_end();
        I != E; ++I) {
     if (I->hasLocalLinkage() && llvmUsedValues.count(I) == 0)
       if (!PreserveDbgInfo || !I->getName().startswith("llvm.dbg"))
         I->setName("");     // Internal symbols can't participate in linkage
   }

   for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
     if (I->hasLocalLinkage() && llvmUsedValues.count(I) == 0)
       if (!PreserveDbgInfo || !I->getName().startswith("llvm.dbg"))
         I->setName("");     // Internal symbols can't participate in linkage
     StripSymtab(I->getValueSymbolTable(), PreserveDbgInfo);
   }

   // Remove all names from types.
   StripTypeNames(M, PreserveDbgInfo);

   return true;
 }

 // StripDebugInfo - 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.
 static bool StripDebugInfo(Module &M) {

   bool Changed = false;

   // Remove all of the calls to the debugger intrinsics, and remove them from
   // the module.
   if (Function *Declare = M.getFunction("llvm.dbg.declare")) {
     while (!Declare->use_empty()) {
       CallInst *CI = cast<CallInst>(Declare->use_back());
       CI->eraseFromParent();
     }
     Declare->eraseFromParent();
     Changed = true;
   }

   if (Function *DbgVal = M.getFunction("llvm.dbg.value")) {
     while (!DbgVal->use_empty()) {
       CallInst *CI = cast<CallInst>(DbgVal->use_back());
       CI->eraseFromParent();
     }
     DbgVal->eraseFromParent();
     Changed = true;
   }

   for (Module::named_metadata_iterator NMI = M.named_metadata_begin(),
          NME = M.named_metadata_end(); NMI != NME;) {
     NamedMDNode *NMD = NMI;
     ++NMI;
     if (NMD->getName().startswith("llvm.dbg.")) {
       NMD->eraseFromParent();
       Changed = true;
     }
   }

   for (Module::iterator MI = M.begin(), ME = M.end(); MI != ME; ++MI)
     for (Function::iterator FI = MI->begin(), FE = MI->end(); FI != FE;
          ++FI)
       for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); BI != BE;
            ++BI) {
         if (!BI->getDebugLoc().isUnknown()) {
           Changed = true;
           BI->setDebugLoc(DebugLoc());
         }
       }

   return Changed;
 }

 bool StripSymbols::runOnModule(Module &M) {
   bool Changed = false;
   Changed |= StripDebugInfo(M);
   if (!OnlyDebugInfo)
     Changed |= StripSymbolNames(M, false);
   return Changed;
 }

 bool StripNonDebugSymbols::runOnModule(Module &M) {
   return StripSymbolNames(M, true);
 }

 bool StripDebugDeclare::runOnModule(Module &M) {

   Function *Declare = M.getFunction("llvm.dbg.declare");
   std::vector<Constant*> DeadConstants;

   if (Declare) {
     while (!Declare->use_empty()) {
       CallInst *CI = cast<CallInst>(Declare->use_back());
       Value *Arg1 = CI->getArgOperand(0);
       Value *Arg2 = CI->getArgOperand(1);
       assert(CI->use_empty() && "llvm.dbg intrinsic should have void result");
       CI->eraseFromParent();
       if (Arg1->use_empty()) {
         if (Constant *C = dyn_cast<Constant>(Arg1))
           DeadConstants.push_back(C);
         else
           RecursivelyDeleteTriviallyDeadInstructions(Arg1);
       }
       if (Arg2->use_empty())
         if (Constant *C = dyn_cast<Constant>(Arg2))
           DeadConstants.push_back(C);
     }
     Declare->eraseFromParent();
   }

   while (!DeadConstants.empty()) {
     Constant *C = DeadConstants.back();
     DeadConstants.pop_back();
     if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
       if (GV->hasLocalLinkage())
         RemoveDeadConstant(GV);
     } else
       RemoveDeadConstant(C);
   }

   return true;
 }

 /// getRealLinkageName - If special LLVM prefix that is used to inform the asm
 /// printer to not emit usual symbol prefix before the symbol name is used then
 /// return linkage name after skipping this special LLVM prefix.
 static StringRef getRealLinkageName(StringRef LinkageName) {
   char One = '\1';
   if (LinkageName.startswith(StringRef(&One, 1)))
     return LinkageName.substr(1);
   return LinkageName;
 }

 bool StripDeadDebugInfo::runOnModule(Module &M) {
   bool Changed = false;

   // Debugging infomration is encoded in llvm IR using metadata. This is designed
   // such a way that debug info for symbols preserved even if symbols are
   // optimized away by the optimizer. This special pass removes debug info for
   // such symbols.

   // llvm.dbg.gv keeps track of debug info for global variables.
   if (NamedMDNode *NMD = M.getNamedMetadata("llvm.dbg.gv")) {
     SmallVector<MDNode *, 8> MDs;
     for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
       if (DIGlobalVariable(NMD->getOperand(i)).Verify())
         MDs.push_back(NMD->getOperand(i));
       else
         Changed = true;
     NMD->eraseFromParent();
     NMD = NULL;

     for (SmallVector<MDNode *, 8>::iterator I = MDs.begin(),
            E = MDs.end(); I != E; ++I) {
       GlobalVariable *GV = DIGlobalVariable(*I).getGlobal();
       if (GV && M.getGlobalVariable(GV->getName(), true)) {
         if (!NMD)
           NMD = M.getOrInsertNamedMetadata("llvm.dbg.gv");
         NMD->addOperand(*I);
       }
       else
         Changed = true;
     }
   }

   // llvm.dbg.sp keeps track of debug info for subprograms.
   if (NamedMDNode *NMD = M.getNamedMetadata("llvm.dbg.sp")) {
     SmallVector<MDNode *, 8> MDs;
     for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
       if (DISubprogram(NMD->getOperand(i)).Verify())
         MDs.push_back(NMD->getOperand(i));
       else
         Changed = true;
     NMD->eraseFromParent();
     NMD = NULL;

     for (SmallVector<MDNode *, 8>::iterator I = MDs.begin(),
            E = MDs.end(); I != E; ++I) {
       bool FnIsLive = false;
       if (Function *F = DISubprogram(*I).getFunction())
         if (M.getFunction(F->getName()))
           FnIsLive = true;
       if (FnIsLive) {
           if (!NMD)
             NMD = M.getOrInsertNamedMetadata("llvm.dbg.sp");
           NMD->addOperand(*I);
       } else {
         // Remove llvm.dbg.lv.fnname named mdnode which may have been used
         // to hold debug info for dead function's local variables.
         StringRef FName = DISubprogram(*I).getLinkageName();
         if (FName.empty())
           FName = DISubprogram(*I).getName();
         if (NamedMDNode *LVNMD =
             M.getNamedMetadata(Twine("llvm.dbg.lv.",
                                      getRealLinkageName(FName))))
           LVNMD->eraseFromParent();
       }
     }
   }

   return Changed;
 }
	//===- StripSymbols.cpp - Strip symbols and debug info from a module ------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// The StripSymbols transformation implements code stripping. Specifically, it
	// can delete:
	//
	// * names for virtual registers
	// * symbols for internal globals and functions
	// * debug information
	//
	// 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/Transforms/IPO.h"
	#include "llvm/ADT/DenseMap.h"
	#include "llvm/ADT/SmallPtrSet.h"
	#include "llvm/Constants.h"
	#include "llvm/DebugInfo.h"
	#include "llvm/DerivedTypes.h"
	#include "llvm/Instructions.h"
	#include "llvm/Module.h"
	#include "llvm/Pass.h"
	#include "llvm/Transforms/Utils/Local.h"
	#include "llvm/TypeFinder.h"
	#include "llvm/ValueSymbolTable.h"
	using namespace llvm;

	namespace {
	class StripSymbols : public ModulePass {
	bool OnlyDebugInfo;
	public:
	static char ID; // Pass identification, replacement for typeid
	explicit StripSymbols(bool ODI = false)
	: ModulePass(ID), OnlyDebugInfo(ODI) {
	initializeStripSymbolsPass(*PassRegistry::getPassRegistry());
	}

	virtual bool runOnModule(Module &M);

	virtual void getAnalysisUsage(AnalysisUsage &AU) const {
	AU.setPreservesAll();
	}
	};

	class StripNonDebugSymbols : public ModulePass {
	public:
	static char ID; // Pass identification, replacement for typeid
	explicit StripNonDebugSymbols()
	: ModulePass(ID) {
	initializeStripNonDebugSymbolsPass(*PassRegistry::getPassRegistry());
	}

	virtual bool runOnModule(Module &M);

	virtual void getAnalysisUsage(AnalysisUsage &AU) const {
	AU.setPreservesAll();
	}
	};

	class StripDebugDeclare : public ModulePass {
	public:
	static char ID; // Pass identification, replacement for typeid
	explicit StripDebugDeclare()
	: ModulePass(ID) {
	initializeStripDebugDeclarePass(*PassRegistry::getPassRegistry());
	}

	virtual bool runOnModule(Module &M);

	virtual void getAnalysisUsage(AnalysisUsage &AU) const {
	AU.setPreservesAll();
	}
	};

	class StripDeadDebugInfo : public ModulePass {
	public:
	static char ID; // Pass identification, replacement for typeid
	explicit StripDeadDebugInfo()
	: ModulePass(ID) {
	initializeStripDeadDebugInfoPass(*PassRegistry::getPassRegistry());
	}

	virtual bool runOnModule(Module &M);

	virtual void getAnalysisUsage(AnalysisUsage &AU) const {
	AU.setPreservesAll();
	}
	};
	}

	char StripSymbols::ID = 0;
	INITIALIZE_PASS(StripSymbols, "strip",
	"Strip all symbols from a module", false, false)

	ModulePass *llvm::createStripSymbolsPass(bool OnlyDebugInfo) {
	return new StripSymbols(OnlyDebugInfo);
	}

	char StripNonDebugSymbols::ID = 0;
	INITIALIZE_PASS(StripNonDebugSymbols, "strip-nondebug",
	"Strip all symbols, except dbg symbols, from a module",
	false, false)

	ModulePass *llvm::createStripNonDebugSymbolsPass() {
	return new StripNonDebugSymbols();
	}

	char StripDebugDeclare::ID = 0;
	INITIALIZE_PASS(StripDebugDeclare, "strip-debug-declare",
	"Strip all llvm.dbg.declare intrinsics", false, false)

	ModulePass *llvm::createStripDebugDeclarePass() {
	return new StripDebugDeclare();
	}

	char StripDeadDebugInfo::ID = 0;
	INITIALIZE_PASS(StripDeadDebugInfo, "strip-dead-debug-info",
	"Strip debug info for unused symbols", false, false)

	ModulePass *llvm::createStripDeadDebugInfoPass() {
	return new StripDeadDebugInfo();
	}

	/// OnlyUsedBy - Return true if V is only used by Usr.
	static bool OnlyUsedBy(Value V, Value Usr) {
	for(Value::use_iterator I = V->use_begin(), E = V->use_end(); I != E; ++I) {
	User U = I;
	if (U != Usr)
	return false;
	}
	return true;
	}

	static void RemoveDeadConstant(Constant *C) {
	assert(C->use_empty() && "Constant is not dead!");
	SmallPtrSet<Constant*, 4> Operands;
	for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
	if (OnlyUsedBy(C->getOperand(i), C))
	Operands.insert(cast<Constant>(C->getOperand(i)));
	if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
	if (!GV->hasLocalLinkage()) return; // Don't delete non static globals.
	GV->eraseFromParent();
	}
	else if (!isa<Function>(C))
	if (isa<CompositeType>(C->getType()))
	C->destroyConstant();

	// If the constant referenced anything, see if we can delete it as well.
	for (SmallPtrSet<Constant*, 4>::iterator OI = Operands.begin(),
	OE = Operands.end(); OI != OE; ++OI)
	RemoveDeadConstant(*OI);
	}

	// Strip the symbol table of its names.
	//
	static void StripSymtab(ValueSymbolTable &ST, bool PreserveDbgInfo) {
	for (ValueSymbolTable::iterator VI = ST.begin(), VE = ST.end(); VI != VE; ) {
	Value *V = VI->getValue();
	++VI;
	if (!isa<GlobalValue>(V) \|\| cast<GlobalValue>(V)->hasLocalLinkage()) {
	if (!PreserveDbgInfo \|\| !V->getName().startswith("llvm.dbg"))
	// Set name to "", removing from symbol table!
	V->setName("");
	}
	}
	}

	// Strip any named types of their names.
	static void StripTypeNames(Module &M, bool PreserveDbgInfo) {
	TypeFinder StructTypes;
	StructTypes.run(M, false);

	for (unsigned i = 0, e = StructTypes.size(); i != e; ++i) {
	StructType *STy = StructTypes[i];
	if (STy->isLiteral() \|\| STy->getName().empty()) continue;

	if (PreserveDbgInfo && STy->getName().startswith("llvm.dbg"))
	continue;

	STy->setName("");
	}
	}

	/// Find values that are marked as llvm.used.
	static void findUsedValues(GlobalVariable *LLVMUsed,
	SmallPtrSet<const GlobalValue*, 8> &UsedValues) {
	if (LLVMUsed == 0) return;
	UsedValues.insert(LLVMUsed);

	ConstantArray *Inits = dyn_cast<ConstantArray>(LLVMUsed->getInitializer());
	if (Inits == 0) return;

	for (unsigned i = 0, e = Inits->getNumOperands(); i != e; ++i)
	if (GlobalValue *GV =
	dyn_cast<GlobalValue>(Inits->getOperand(i)->stripPointerCasts()))
	UsedValues.insert(GV);
	}

	/// StripSymbolNames - Strip symbol names.
	static bool StripSymbolNames(Module &M, bool PreserveDbgInfo) {

	SmallPtrSet<const GlobalValue*, 8> llvmUsedValues;
	findUsedValues(M.getGlobalVariable("llvm.used"), llvmUsedValues);
	findUsedValues(M.getGlobalVariable("llvm.compiler.used"), llvmUsedValues);

	for (Module::global_iterator I = M.global_begin(), E = M.global_end();
	I != E; ++I) {
	if (I->hasLocalLinkage() && llvmUsedValues.count(I) == 0)
	if (!PreserveDbgInfo \|\| !I->getName().startswith("llvm.dbg"))
	I->setName(""); // Internal symbols can't participate in linkage
	}

	for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
	if (I->hasLocalLinkage() && llvmUsedValues.count(I) == 0)
	if (!PreserveDbgInfo \|\| !I->getName().startswith("llvm.dbg"))
	I->setName(""); // Internal symbols can't participate in linkage
	StripSymtab(I->getValueSymbolTable(), PreserveDbgInfo);
	}

	// Remove all names from types.
	StripTypeNames(M, PreserveDbgInfo);

	return true;
	}

	// StripDebugInfo - 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.
	static bool StripDebugInfo(Module &M) {

	bool Changed = false;

	// Remove all of the calls to the debugger intrinsics, and remove them from
	// the module.
	if (Function *Declare = M.getFunction("llvm.dbg.declare")) {
	while (!Declare->use_empty()) {
	CallInst *CI = cast<CallInst>(Declare->use_back());
	CI->eraseFromParent();
	}
	Declare->eraseFromParent();
	Changed = true;
	}

	if (Function *DbgVal = M.getFunction("llvm.dbg.value")) {
	while (!DbgVal->use_empty()) {
	CallInst *CI = cast<CallInst>(DbgVal->use_back());
	CI->eraseFromParent();
	}
	DbgVal->eraseFromParent();
	Changed = true;
	}

	for (Module::named_metadata_iterator NMI = M.named_metadata_begin(),
	NME = M.named_metadata_end(); NMI != NME;) {
	NamedMDNode *NMD = NMI;
	++NMI;
	if (NMD->getName().startswith("llvm.dbg.")) {
	NMD->eraseFromParent();
	Changed = true;
	}
	}

	for (Module::iterator MI = M.begin(), ME = M.end(); MI != ME; ++MI)
	for (Function::iterator FI = MI->begin(), FE = MI->end(); FI != FE;
	++FI)
	for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); BI != BE;
	++BI) {
	if (!BI->getDebugLoc().isUnknown()) {
	Changed = true;
	BI->setDebugLoc(DebugLoc());
	}
	}

	return Changed;
	}

	bool StripSymbols::runOnModule(Module &M) {
	bool Changed = false;
	Changed \|= StripDebugInfo(M);
	if (!OnlyDebugInfo)
	Changed \|= StripSymbolNames(M, false);
	return Changed;
	}

	bool StripNonDebugSymbols::runOnModule(Module &M) {
	return StripSymbolNames(M, true);
	}

	bool StripDebugDeclare::runOnModule(Module &M) {

	Function *Declare = M.getFunction("llvm.dbg.declare");
	std::vector<Constant*> DeadConstants;

	if (Declare) {
	while (!Declare->use_empty()) {
	CallInst *CI = cast<CallInst>(Declare->use_back());
	Value *Arg1 = CI->getArgOperand(0);
	Value *Arg2 = CI->getArgOperand(1);
	assert(CI->use_empty() && "llvm.dbg intrinsic should have void result");
	CI->eraseFromParent();
	if (Arg1->use_empty()) {
	if (Constant *C = dyn_cast<Constant>(Arg1))
	DeadConstants.push_back(C);
	else
	RecursivelyDeleteTriviallyDeadInstructions(Arg1);
	}
	if (Arg2->use_empty())
	if (Constant *C = dyn_cast<Constant>(Arg2))
	DeadConstants.push_back(C);
	}
	Declare->eraseFromParent();
	}

	while (!DeadConstants.empty()) {
	Constant *C = DeadConstants.back();
	DeadConstants.pop_back();
	if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
	if (GV->hasLocalLinkage())
	RemoveDeadConstant(GV);
	} else
	RemoveDeadConstant(C);
	}

	return true;
	}

	/// getRealLinkageName - If special LLVM prefix that is used to inform the asm
	/// printer to not emit usual symbol prefix before the symbol name is used then
	/// return linkage name after skipping this special LLVM prefix.
	static StringRef getRealLinkageName(StringRef LinkageName) {
	char One = '\1';
	if (LinkageName.startswith(StringRef(&One, 1)))
	return LinkageName.substr(1);
	return LinkageName;
	}

	bool StripDeadDebugInfo::runOnModule(Module &M) {
	bool Changed = false;

	// Debugging infomration is encoded in llvm IR using metadata. This is designed
	// such a way that debug info for symbols preserved even if symbols are
	// optimized away by the optimizer. This special pass removes debug info for
	// such symbols.

	// llvm.dbg.gv keeps track of debug info for global variables.
	if (NamedMDNode *NMD = M.getNamedMetadata("llvm.dbg.gv")) {
	SmallVector<MDNode *, 8> MDs;
	for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
	if (DIGlobalVariable(NMD->getOperand(i)).Verify())
	MDs.push_back(NMD->getOperand(i));
	else
	Changed = true;
	NMD->eraseFromParent();
	NMD = NULL;

	for (SmallVector<MDNode *, 8>::iterator I = MDs.begin(),
	E = MDs.end(); I != E; ++I) {
	GlobalVariable GV = DIGlobalVariable(I).getGlobal();
	if (GV && M.getGlobalVariable(GV->getName(), true)) {
	if (!NMD)
	NMD = M.getOrInsertNamedMetadata("llvm.dbg.gv");
	NMD->addOperand(*I);
	}
	else
	Changed = true;
	}
	}

	// llvm.dbg.sp keeps track of debug info for subprograms.
	if (NamedMDNode *NMD = M.getNamedMetadata("llvm.dbg.sp")) {
	SmallVector<MDNode *, 8> MDs;
	for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
	if (DISubprogram(NMD->getOperand(i)).Verify())
	MDs.push_back(NMD->getOperand(i));
	else
	Changed = true;
	NMD->eraseFromParent();
	NMD = NULL;

	for (SmallVector<MDNode *, 8>::iterator I = MDs.begin(),
	E = MDs.end(); I != E; ++I) {
	bool FnIsLive = false;
	if (Function F = DISubprogram(I).getFunction())
	if (M.getFunction(F->getName()))
	FnIsLive = true;
	if (FnIsLive) {
	if (!NMD)
	NMD = M.getOrInsertNamedMetadata("llvm.dbg.sp");
	NMD->addOperand(*I);
	} else {
	// Remove llvm.dbg.lv.fnname named mdnode which may have been used
	// to hold debug info for dead function's local variables.
	StringRef FName = DISubprogram(*I).getLinkageName();
	if (FName.empty())
	FName = DISubprogram(*I).getName();
	if (NamedMDNode *LVNMD =
	M.getNamedMetadata(Twine("llvm.dbg.lv.",
	getRealLinkageName(FName))))
	LVNMD->eraseFromParent();
	}
	}
	}

	return Changed;
	}