lib/Transforms/Instrumentation/TraceValues.cpp - platform/external/llvm - Gitiles

 //===- TraceValues.cpp - Value Tracing for debugging -------------*- C++ -*--=//
 //
 // Support for inserting LLVM code to print values at basic block and function
 // exits.
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/Transforms/Instrumentation/TraceValues.h"
 #include "llvm/GlobalVariable.h"
 #include "llvm/Constants.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/iMemory.h"
 #include "llvm/iTerminators.h"
 #include "llvm/iOther.h"
 #include "llvm/Module.h"
 #include "llvm/Pass.h"
 #include "llvm/Assembly/Writer.h"
 #include "Support/CommandLine.h"
 #include "Support/StringExtras.h"
 #include <algorithm>
 #include <sstream>
 using std::vector;
 using std::string;

 static cl::opt<bool>
 DisablePtrHashing("tracedisablehashdisable", cl::Hidden,
                   cl::desc("Disable pointer hashing"));

 static cl::list<string>
 TraceFuncName("tracefunc", cl::desc("trace only specific functions"),
               cl::value_desc("function"), cl::Hidden);

 static void TraceValuesAtBBExit(BasicBlock *BB,
                                 Function *Printf, Function* HashPtrToSeqNum,
                                 vector<Instruction*> *valuesStoredInFunction);

 // We trace a particular function if no functions to trace were specified
 // or if the function is in the specified list.
 //
 inline static bool
 TraceThisFunction(Function &func)
 {
   if (TraceFuncName.size() == 0)
     return true;

   return std::find(TraceFuncName.begin(), TraceFuncName.end(), func.getName())
                   != TraceFuncName.end();
 }


 namespace {
   struct ExternalFuncs {
     Function *PrintfFunc, *HashPtrFunc, *ReleasePtrFunc;
     Function *RecordPtrFunc, *PushOnEntryFunc, *ReleaseOnReturnFunc;
     void doInitialization(Module &M); // Add prototypes for external functions
   };

   class InsertTraceCode : public FunctionPass {
   protected:
     ExternalFuncs externalFuncs;
   public:

     // Add a prototype for runtime functions not already in the program.
     //
     bool doInitialization(Module &M);

     //--------------------------------------------------------------------------
     // Function InsertCodeToTraceValues
     //
     // Inserts tracing code for all live values at basic block and/or function
     // exits as specified by `traceBasicBlockExits' and `traceFunctionExits'.
     //
     bool doit(Function *M);

     virtual void handleBasicBlock(BasicBlock *BB, vector<Instruction*> &VI) = 0;

     // runOnFunction - This method does the work.
     //
     bool runOnFunction(Function &F);

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

   struct FunctionTracer : public InsertTraceCode {
     // Ignore basic blocks here...
     virtual void handleBasicBlock(BasicBlock *BB, vector<Instruction*> &VI) {}
   };

   struct BasicBlockTracer : public InsertTraceCode {
     // Trace basic blocks here...
     virtual void handleBasicBlock(BasicBlock *BB, vector<Instruction*> &VI) {
       TraceValuesAtBBExit(BB, externalFuncs.PrintfFunc,
                           externalFuncs.HashPtrFunc, &VI);
     }
   };

   // Register the passes...
   RegisterOpt<FunctionTracer>  X("tracem","Insert Function trace code only");
   RegisterOpt<BasicBlockTracer> Y("trace","Insert BB and Function trace code");
 } // end anonymous namespace


 Pass *createTraceValuesPassForFunction() {     // Just trace functions
   return new FunctionTracer();
 }

 Pass *createTraceValuesPassForBasicBlocks() {  // Trace BB's and functions
   return new BasicBlockTracer();
 }


 // Add a prototype for external functions used by the tracing code.
 //
 void ExternalFuncs::doInitialization(Module &M) {
   const Type *SBP = PointerType::get(Type::SByteTy);
   const FunctionType *MTy =
     FunctionType::get(Type::IntTy, vector<const Type*>(1, SBP), true);
   PrintfFunc = M.getOrInsertFunction("printf", MTy);

   // uint (sbyte*)
   const FunctionType *hashFuncTy =
     FunctionType::get(Type::UIntTy, vector<const Type*>(1, SBP), false);
   HashPtrFunc = M.getOrInsertFunction("HashPointerToSeqNum", hashFuncTy);

   // void (sbyte*)
   const FunctionType *voidSBPFuncTy =
     FunctionType::get(Type::VoidTy, vector<const Type*>(1, SBP), false);

   ReleasePtrFunc = M.getOrInsertFunction("ReleasePointerSeqNum", voidSBPFuncTy);
   RecordPtrFunc  = M.getOrInsertFunction("RecordPointer", voidSBPFuncTy);

   const FunctionType *voidvoidFuncTy =
     FunctionType::get(Type::VoidTy, vector<const Type*>(), false);

   PushOnEntryFunc = M.getOrInsertFunction("PushPointerSet", voidvoidFuncTy);
   ReleaseOnReturnFunc = M.getOrInsertFunction("ReleasePointersPopSet",
                                                voidvoidFuncTy);
 }


 // Add a prototype for external functions used by the tracing code.
 //
 bool InsertTraceCode::doInitialization(Module &M) {
   externalFuncs.doInitialization(M);
   return false;
 }


 static inline GlobalVariable *getStringRef(Module *M, const string &str) {
   // Create a constant internal string reference...
   Constant *Init = ConstantArray::get(str);

   // Create the global variable and record it in the module
   // The GV will be renamed to a unique name if needed.
   GlobalVariable *GV = new GlobalVariable(Init->getType(), true, true, Init,
                                           "trstr");
   M->getGlobalList().push_back(GV);
   return GV;
 }


 //
 // Check if this instruction has any uses outside its basic block,
 // or if it used by either a Call or Return instruction.
 //
 static inline bool LiveAtBBExit(const Instruction* I) {
   const BasicBlock *BB = I->getParent();
   for (Value::use_const_iterator U = I->use_begin(); U != I->use_end(); ++U)
     if (const Instruction *UI = dyn_cast<Instruction>(*U))
       if (UI->getParent() != BB || isa<ReturnInst>(UI))
         return true;

   return false;
 }


 static inline bool TraceThisOpCode(unsigned opCode) {
   // Explicitly test for opCodes *not* to trace so that any new opcodes will
   // be traced by default (VoidTy's are already excluded)
   //
   return (opCode  < Instruction::FirstOtherOp &&
           opCode != Instruction::Alloca &&
           opCode != Instruction::PHINode &&
           opCode != Instruction::Cast);
 }


 static bool ShouldTraceValue(const Instruction *I) {
   return
     I->getType() != Type::VoidTy && LiveAtBBExit(I) &&
     TraceThisOpCode(I->getOpcode());
 }

 static string getPrintfCodeFor(const Value *V) {
   if (V == 0) return "";
   if (V->getType()->isFloatingPoint())
     return "%g";
   else if (V->getType() == Type::LabelTy)
     return "0x%p";
   else if (isa<PointerType>(V->getType()))
     return DisablePtrHashing ? "0x%p" : "%d";
   else if (V->getType()->isIntegral() || V->getType() == Type::BoolTy)
     return "%d";

   assert(0 && "Illegal value to print out...");
   return "";
 }


 static void InsertPrintInst(Value *V,BasicBlock *BB, BasicBlock::iterator &BBI,
                             string Message,
                             Function *Printf, Function* HashPtrToSeqNum) {
   // Escape Message by replacing all % characters with %% chars.
   unsigned Offset = 0;
   while ((Offset = Message.find('%', Offset)) != string::npos) {
     Message.replace(Offset, 1, "%%");
     Offset += 2;  // Skip over the new %'s
   }

   Module *Mod = BB->getParent()->getParent();

   // Turn the marker string into a global variable...
   GlobalVariable *fmtVal = getStringRef(Mod, Message+getPrintfCodeFor(V)+"\n");

   // Turn the format string into an sbyte *
   Instruction *GEP =
     new GetElementPtrInst(fmtVal,
                           vector<Value*>(2,ConstantUInt::get(Type::UIntTy, 0)),
                           "trstr");
   BBI = ++BB->getInstList().insert(BBI, GEP);

   // Insert a call to the hash function if this is a pointer value
   if (V && isa<PointerType>(V->getType()) && !DisablePtrHashing) {
     const Type *SBP = PointerType::get(Type::SByteTy);
     if (V->getType() != SBP) {   // Cast pointer to be sbyte*
       Instruction *I = new CastInst(V, SBP, "Hash_cast");
       BBI = ++BB->getInstList().insert(BBI, I);
       V = I;
     }

     vector<Value*> HashArgs(1, V);
     V = new CallInst(HashPtrToSeqNum, HashArgs, "ptrSeqNum");
     BBI = ++BB->getInstList().insert(BBI, cast<Instruction>(V));
   }

   // Insert the first print instruction to print the string flag:
   vector<Value*> PrintArgs;
   PrintArgs.push_back(GEP);
   if (V) PrintArgs.push_back(V);
   Instruction *I = new CallInst(Printf, PrintArgs, "trace");
   BBI = ++BB->getInstList().insert(BBI, I);
 }


 static void InsertVerbosePrintInst(Value *V, BasicBlock *BB,
                                    BasicBlock::iterator &BBI,
                                    const string &Message, Function *Printf,
                                    Function* HashPtrToSeqNum) {
   std::ostringstream OutStr;
   if (V) WriteAsOperand(OutStr, V);
   InsertPrintInst(V, BB, BBI, Message+OutStr.str()+" = ",
                   Printf, HashPtrToSeqNum);
 }

 static void
 InsertReleaseInst(Value *V, BasicBlock *BB,
                   BasicBlock::iterator &BBI,
                   Function* ReleasePtrFunc) {

   const Type *SBP = PointerType::get(Type::SByteTy);
   if (V->getType() != SBP) {   // Cast pointer to be sbyte*
     Instruction *I = new CastInst(V, SBP, "RPSN_cast");
     BBI = ++BB->getInstList().insert(BBI, I);
     V = I;
   }
   vector<Value*> releaseArgs(1, V);
   Instruction *I = new CallInst(ReleasePtrFunc, releaseArgs);
   BBI = ++BB->getInstList().insert(BBI, I);
 }

 static void
 InsertRecordInst(Value *V, BasicBlock *BB,
                  BasicBlock::iterator &BBI,
                  Function* RecordPtrFunc) {
     const Type *SBP = PointerType::get(Type::SByteTy);
   if (V->getType() != SBP) {   // Cast pointer to be sbyte*
     Instruction *I = new CastInst(V, SBP, "RP_cast");
     BBI = ++BB->getInstList().insert(BBI, I);
     V = I;
   }
   vector<Value*> releaseArgs(1, V);
   Instruction *I = new CallInst(RecordPtrFunc, releaseArgs);
   BBI = ++BB->getInstList().insert(BBI, I);
 }

 static void
 InsertPushOnEntryFunc(Function *M,
                       Function* PushOnEntryFunc) {
   // Get an iterator to point to the insertion location
   BasicBlock &BB = M->getEntryNode();
   BB.getInstList().insert(BB.begin(), new CallInst(PushOnEntryFunc,
                                                    vector<Value*>()));
 }

 static void
 InsertReleaseRecordedInst(BasicBlock *BB,
                           Function* ReleaseOnReturnFunc) {
   BasicBlock::iterator BBI = --BB->end();
   BBI = ++BB->getInstList().insert(BBI, new CallInst(ReleaseOnReturnFunc,
                                                      vector<Value*>()));
 }

 // Look for alloca and free instructions. These are the ptrs to release.
 // Release the free'd pointers immediately.  Record the alloca'd pointers
 // to be released on return from the current function.
 //
 static void
 ReleasePtrSeqNumbers(BasicBlock *BB,
                      ExternalFuncs& externalFuncs) {

   for (BasicBlock::iterator II=BB->begin(); II != BB->end(); ++II) {
     if (FreeInst *FI = dyn_cast<FreeInst>(&*II))
       InsertReleaseInst(FI->getOperand(0), BB,II,externalFuncs.ReleasePtrFunc);
     else if (AllocaInst *AI = dyn_cast<AllocaInst>(&*II))
       {
         BasicBlock::iterator nextI = ++II;
         InsertRecordInst(AI, BB, nextI, externalFuncs.RecordPtrFunc);
         II = --nextI;
       }
   }
 }


 // Insert print instructions at the end of basic block BB for each value
 // computed in BB that is live at the end of BB,
 // or that is stored to memory in BB.
 // If the value is stored to memory, we load it back before printing it
 // We also return all such loaded values in the vector valuesStoredInFunction
 // for printing at the exit from the function.  (Note that in each invocation
 // of the function, this will only get the last value stored for each static
 // store instruction).
 //
 static void TraceValuesAtBBExit(BasicBlock *BB,
                                 Function *Printf, Function* HashPtrToSeqNum,
                                 vector<Instruction*> *valuesStoredInFunction) {
   // Get an iterator to point to the insertion location, which is
   // just before the terminator instruction.
   //
   BasicBlock::iterator InsertPos = --BB->end();
   assert(InsertPos->isTerminator());

   std::ostringstream OutStr;
   WriteAsOperand(OutStr, BB, false);
   InsertPrintInst(0, BB, InsertPos, "LEAVING BB:" + OutStr.str(),
                   Printf, HashPtrToSeqNum);

   // Insert a print instruction for each instruction preceding InsertPos.
   // The print instructions must go before InsertPos, so we use the
   // instruction *preceding* InsertPos to check when to terminate the loop.
   //
   if (InsertPos != BB->begin()) { // there's at least one instr before InsertPos
     BasicBlock::iterator II = BB->begin(), IEincl = InsertPos;
     --IEincl;
     do {                          // do from II up to IEincl, inclusive
       if (StoreInst *SI = dyn_cast<StoreInst>(&*II)) {
         assert(valuesStoredInFunction &&
                "Should not be printing a store instruction at function exit");
         LoadInst *LI = new LoadInst(SI->getPointerOperand(), SI->copyIndices(),
                                   "reload."+SI->getPointerOperand()->getName());
         InsertPos = ++BB->getInstList().insert(InsertPos, LI);
         valuesStoredInFunction->push_back(LI);
       }
       if (ShouldTraceValue(II))
         InsertVerbosePrintInst(II, BB, InsertPos, "  ", Printf,HashPtrToSeqNum);
     } while (II++ != IEincl);
   }
 }

 static inline void InsertCodeToShowFunctionEntry(Function &F, Function *Printf,
                                                  Function* HashPtrToSeqNum){
   // Get an iterator to point to the insertion location
   BasicBlock &BB = F.getEntryNode();
   BasicBlock::iterator BBI = BB.begin();

   std::ostringstream OutStr;
   WriteAsOperand(OutStr, &F, true);
   InsertPrintInst(0, &BB, BBI, "ENTERING FUNCTION: " + OutStr.str(),
                   Printf, HashPtrToSeqNum);

   // Now print all the incoming arguments
   unsigned ArgNo = 0;
   for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I, ++ArgNo){
     InsertVerbosePrintInst(I, &BB, BBI,
                            "  Arg #" + utostr(ArgNo) + ": ", Printf,
                            HashPtrToSeqNum);
   }
 }


 static inline void InsertCodeToShowFunctionExit(BasicBlock *BB,
                                                 Function *Printf,
                                                 Function* HashPtrToSeqNum) {
   // Get an iterator to point to the insertion location
   BasicBlock::iterator BBI = --BB->end();
   ReturnInst &Ret = cast<ReturnInst>(BB->back());

   std::ostringstream OutStr;
   WriteAsOperand(OutStr, BB->getParent(), true);
   InsertPrintInst(0, BB, BBI, "LEAVING  FUNCTION: " + OutStr.str(),
                   Printf, HashPtrToSeqNum);

   // print the return value, if any
   if (BB->getParent()->getReturnType() != Type::VoidTy)
     InsertPrintInst(Ret.getReturnValue(), BB, BBI, "  Returning: ",
                     Printf, HashPtrToSeqNum);
 }


 bool InsertTraceCode::runOnFunction(Function &F) {
   if (!TraceThisFunction(F))
     return false;

   vector<Instruction*> valuesStoredInFunction;
   vector<BasicBlock*>  exitBlocks;

   // Insert code to trace values at function entry
   InsertCodeToShowFunctionEntry(F, externalFuncs.PrintfFunc,
                                 externalFuncs.HashPtrFunc);

   // Push a pointer set for recording alloca'd pointers at entry.
   if (!DisablePtrHashing)
     InsertPushOnEntryFunc(&F, externalFuncs.PushOnEntryFunc);

   for (Function::iterator BB = F.begin(); BB != F.end(); ++BB) {
     if (isa<ReturnInst>(BB->getTerminator()))
       exitBlocks.push_back(BB); // record this as an exit block

     // Insert trace code if this basic block is interesting...
     handleBasicBlock(BB, valuesStoredInFunction);

     if (!DisablePtrHashing)          // release seq. numbers on free/ret
       ReleasePtrSeqNumbers(BB, externalFuncs);
   }

   for (unsigned i=0; i != exitBlocks.size(); ++i)
     {
       // Insert code to trace values at function exit
       InsertCodeToShowFunctionExit(exitBlocks[i], externalFuncs.PrintfFunc,
                                    externalFuncs.HashPtrFunc);

       // Release all recorded pointers before RETURN.  Do this LAST!
       if (!DisablePtrHashing)
         InsertReleaseRecordedInst(exitBlocks[i],
                                   externalFuncs.ReleaseOnReturnFunc);
     }

   return true;
 }
	//===- TraceValues.cpp - Value Tracing for debugging -------------- C++ ---=//
	//
	// Support for inserting LLVM code to print values at basic block and function
	// exits.
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/Transforms/Instrumentation/TraceValues.h"
	#include "llvm/GlobalVariable.h"
	#include "llvm/Constants.h"
	#include "llvm/DerivedTypes.h"
	#include "llvm/iMemory.h"
	#include "llvm/iTerminators.h"
	#include "llvm/iOther.h"
	#include "llvm/Module.h"
	#include "llvm/Pass.h"
	#include "llvm/Assembly/Writer.h"
	#include "Support/CommandLine.h"
	#include "Support/StringExtras.h"
	#include <algorithm>
	#include <sstream>
	using std::vector;
	using std::string;

	static cl::opt<bool>
	DisablePtrHashing("tracedisablehashdisable", cl::Hidden,
	cl::desc("Disable pointer hashing"));

	static cl::list<string>
	TraceFuncName("tracefunc", cl::desc("trace only specific functions"),
	cl::value_desc("function"), cl::Hidden);

	static void TraceValuesAtBBExit(BasicBlock *BB,
	Function Printf, Function HashPtrToSeqNum,
	vector<Instruction> valuesStoredInFunction);

	// We trace a particular function if no functions to trace were specified
	// or if the function is in the specified list.
	//
	inline static bool
	TraceThisFunction(Function &func)
	{
	if (TraceFuncName.size() == 0)
	return true;

	return std::find(TraceFuncName.begin(), TraceFuncName.end(), func.getName())
	!= TraceFuncName.end();
	}


	namespace {
	struct ExternalFuncs {
	Function PrintfFunc, HashPtrFunc, *ReleasePtrFunc;
	Function RecordPtrFunc, PushOnEntryFunc, *ReleaseOnReturnFunc;
	void doInitialization(Module &M); // Add prototypes for external functions
	};

	class InsertTraceCode : public FunctionPass {
	protected:
	ExternalFuncs externalFuncs;
	public:

	// Add a prototype for runtime functions not already in the program.
	//
	bool doInitialization(Module &M);

	//--------------------------------------------------------------------------
	// Function InsertCodeToTraceValues
	//
	// Inserts tracing code for all live values at basic block and/or function
	// exits as specified by `traceBasicBlockExits' and `traceFunctionExits'.
	//
	bool doit(Function *M);

	virtual void handleBasicBlock(BasicBlock BB, vector<Instruction> &VI) = 0;

	// runOnFunction - This method does the work.
	//
	bool runOnFunction(Function &F);

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

	struct FunctionTracer : public InsertTraceCode {
	// Ignore basic blocks here...
	virtual void handleBasicBlock(BasicBlock BB, vector<Instruction> &VI) {}
	};

	struct BasicBlockTracer : public InsertTraceCode {
	// Trace basic blocks here...
	virtual void handleBasicBlock(BasicBlock BB, vector<Instruction> &VI) {
	TraceValuesAtBBExit(BB, externalFuncs.PrintfFunc,
	externalFuncs.HashPtrFunc, &VI);
	}
	};

	// Register the passes...
	RegisterOpt<FunctionTracer> X("tracem","Insert Function trace code only");
	RegisterOpt<BasicBlockTracer> Y("trace","Insert BB and Function trace code");
	} // end anonymous namespace


	Pass *createTraceValuesPassForFunction() { // Just trace functions
	return new FunctionTracer();
	}

	Pass *createTraceValuesPassForBasicBlocks() { // Trace BB's and functions
	return new BasicBlockTracer();
	}


	// Add a prototype for external functions used by the tracing code.
	//
	void ExternalFuncs::doInitialization(Module &M) {
	const Type *SBP = PointerType::get(Type::SByteTy);
	const FunctionType *MTy =
	FunctionType::get(Type::IntTy, vector<const Type*>(1, SBP), true);
	PrintfFunc = M.getOrInsertFunction("printf", MTy);

	// uint (sbyte*)
	const FunctionType *hashFuncTy =
	FunctionType::get(Type::UIntTy, vector<const Type*>(1, SBP), false);
	HashPtrFunc = M.getOrInsertFunction("HashPointerToSeqNum", hashFuncTy);

	// void (sbyte*)
	const FunctionType *voidSBPFuncTy =
	FunctionType::get(Type::VoidTy, vector<const Type*>(1, SBP), false);

	ReleasePtrFunc = M.getOrInsertFunction("ReleasePointerSeqNum", voidSBPFuncTy);
	RecordPtrFunc = M.getOrInsertFunction("RecordPointer", voidSBPFuncTy);

	const FunctionType *voidvoidFuncTy =
	FunctionType::get(Type::VoidTy, vector<const Type*>(), false);

	PushOnEntryFunc = M.getOrInsertFunction("PushPointerSet", voidvoidFuncTy);
	ReleaseOnReturnFunc = M.getOrInsertFunction("ReleasePointersPopSet",
	voidvoidFuncTy);
	}


	// Add a prototype for external functions used by the tracing code.
	//
	bool InsertTraceCode::doInitialization(Module &M) {
	externalFuncs.doInitialization(M);
	return false;
	}


	static inline GlobalVariable getStringRef(Module M, const string &str) {
	// Create a constant internal string reference...
	Constant *Init = ConstantArray::get(str);

	// Create the global variable and record it in the module
	// The GV will be renamed to a unique name if needed.
	GlobalVariable *GV = new GlobalVariable(Init->getType(), true, true, Init,
	"trstr");
	M->getGlobalList().push_back(GV);
	return GV;
	}


	//
	// Check if this instruction has any uses outside its basic block,
	// or if it used by either a Call or Return instruction.
	//
	static inline bool LiveAtBBExit(const Instruction* I) {
	const BasicBlock *BB = I->getParent();
	for (Value::use_const_iterator U = I->use_begin(); U != I->use_end(); ++U)
	if (const Instruction UI = dyn_cast<Instruction>(U))
	if (UI->getParent() != BB \|\| isa<ReturnInst>(UI))
	return true;

	return false;
	}


	static inline bool TraceThisOpCode(unsigned opCode) {
	// Explicitly test for opCodes not to trace so that any new opcodes will
	// be traced by default (VoidTy's are already excluded)
	//
	return (opCode < Instruction::FirstOtherOp &&
	opCode != Instruction::Alloca &&
	opCode != Instruction::PHINode &&
	opCode != Instruction::Cast);
	}


	static bool ShouldTraceValue(const Instruction *I) {
	return
	I->getType() != Type::VoidTy && LiveAtBBExit(I) &&
	TraceThisOpCode(I->getOpcode());
	}

	static string getPrintfCodeFor(const Value *V) {
	if (V == 0) return "";
	if (V->getType()->isFloatingPoint())
	return "%g";
	else if (V->getType() == Type::LabelTy)
	return "0x%p";
	else if (isa<PointerType>(V->getType()))
	return DisablePtrHashing ? "0x%p" : "%d";
	else if (V->getType()->isIntegral() \|\| V->getType() == Type::BoolTy)
	return "%d";

	assert(0 && "Illegal value to print out...");
	return "";
	}


	static void InsertPrintInst(Value V,BasicBlock BB, BasicBlock::iterator &BBI,
	string Message,
	Function Printf, Function HashPtrToSeqNum) {
	// Escape Message by replacing all % characters with %% chars.
	unsigned Offset = 0;
	while ((Offset = Message.find('%', Offset)) != string::npos) {
	Message.replace(Offset, 1, "%%");
	Offset += 2; // Skip over the new %'s
	}

	Module *Mod = BB->getParent()->getParent();

	// Turn the marker string into a global variable...
	GlobalVariable *fmtVal = getStringRef(Mod, Message+getPrintfCodeFor(V)+"\n");

	// Turn the format string into an sbyte *
	Instruction *GEP =
	new GetElementPtrInst(fmtVal,
	vector<Value*>(2,ConstantUInt::get(Type::UIntTy, 0)),
	"trstr");
	BBI = ++BB->getInstList().insert(BBI, GEP);

	// Insert a call to the hash function if this is a pointer value
	if (V && isa<PointerType>(V->getType()) && !DisablePtrHashing) {
	const Type *SBP = PointerType::get(Type::SByteTy);
	if (V->getType() != SBP) { // Cast pointer to be sbyte*
	Instruction *I = new CastInst(V, SBP, "Hash_cast");
	BBI = ++BB->getInstList().insert(BBI, I);
	V = I;
	}

	vector<Value*> HashArgs(1, V);
	V = new CallInst(HashPtrToSeqNum, HashArgs, "ptrSeqNum");
	BBI = ++BB->getInstList().insert(BBI, cast<Instruction>(V));
	}

	// Insert the first print instruction to print the string flag:
	vector<Value*> PrintArgs;
	PrintArgs.push_back(GEP);
	if (V) PrintArgs.push_back(V);
	Instruction *I = new CallInst(Printf, PrintArgs, "trace");
	BBI = ++BB->getInstList().insert(BBI, I);
	}


	static void InsertVerbosePrintInst(Value V, BasicBlock BB,
	BasicBlock::iterator &BBI,
	const string &Message, Function *Printf,
	Function* HashPtrToSeqNum) {
	std::ostringstream OutStr;
	if (V) WriteAsOperand(OutStr, V);
	InsertPrintInst(V, BB, BBI, Message+OutStr.str()+" = ",
	Printf, HashPtrToSeqNum);
	}

	static void
	InsertReleaseInst(Value V, BasicBlock BB,
	BasicBlock::iterator &BBI,
	Function* ReleasePtrFunc) {

	const Type *SBP = PointerType::get(Type::SByteTy);
	if (V->getType() != SBP) { // Cast pointer to be sbyte*
	Instruction *I = new CastInst(V, SBP, "RPSN_cast");
	BBI = ++BB->getInstList().insert(BBI, I);
	V = I;
	}
	vector<Value*> releaseArgs(1, V);
	Instruction *I = new CallInst(ReleasePtrFunc, releaseArgs);
	BBI = ++BB->getInstList().insert(BBI, I);
	}

	static void
	InsertRecordInst(Value V, BasicBlock BB,
	BasicBlock::iterator &BBI,
	Function* RecordPtrFunc) {
	const Type *SBP = PointerType::get(Type::SByteTy);
	if (V->getType() != SBP) { // Cast pointer to be sbyte*
	Instruction *I = new CastInst(V, SBP, "RP_cast");
	BBI = ++BB->getInstList().insert(BBI, I);
	V = I;
	}
	vector<Value*> releaseArgs(1, V);
	Instruction *I = new CallInst(RecordPtrFunc, releaseArgs);
	BBI = ++BB->getInstList().insert(BBI, I);
	}

	static void
	InsertPushOnEntryFunc(Function *M,
	Function* PushOnEntryFunc) {
	// Get an iterator to point to the insertion location
	BasicBlock &BB = M->getEntryNode();
	BB.getInstList().insert(BB.begin(), new CallInst(PushOnEntryFunc,
	vector<Value*>()));
	}

	static void
	InsertReleaseRecordedInst(BasicBlock *BB,
	Function* ReleaseOnReturnFunc) {
	BasicBlock::iterator BBI = --BB->end();
	BBI = ++BB->getInstList().insert(BBI, new CallInst(ReleaseOnReturnFunc,
	vector<Value*>()));
	}

	// Look for alloca and free instructions. These are the ptrs to release.
	// Release the free'd pointers immediately. Record the alloca'd pointers
	// to be released on return from the current function.
	//
	static void
	ReleasePtrSeqNumbers(BasicBlock *BB,
	ExternalFuncs& externalFuncs) {

	for (BasicBlock::iterator II=BB->begin(); II != BB->end(); ++II) {
	if (FreeInst FI = dyn_cast<FreeInst>(&II))
	InsertReleaseInst(FI->getOperand(0), BB,II,externalFuncs.ReleasePtrFunc);
	else if (AllocaInst AI = dyn_cast<AllocaInst>(&II))
	{
	BasicBlock::iterator nextI = ++II;
	InsertRecordInst(AI, BB, nextI, externalFuncs.RecordPtrFunc);
	II = --nextI;
	}
	}
	}


	// Insert print instructions at the end of basic block BB for each value
	// computed in BB that is live at the end of BB,
	// or that is stored to memory in BB.
	// If the value is stored to memory, we load it back before printing it
	// We also return all such loaded values in the vector valuesStoredInFunction
	// for printing at the exit from the function. (Note that in each invocation
	// of the function, this will only get the last value stored for each static
	// store instruction).
	//
	static void TraceValuesAtBBExit(BasicBlock *BB,
	Function Printf, Function HashPtrToSeqNum,
	vector<Instruction> valuesStoredInFunction) {
	// Get an iterator to point to the insertion location, which is
	// just before the terminator instruction.
	//
	BasicBlock::iterator InsertPos = --BB->end();
	assert(InsertPos->isTerminator());

	std::ostringstream OutStr;
	WriteAsOperand(OutStr, BB, false);
	InsertPrintInst(0, BB, InsertPos, "LEAVING BB:" + OutStr.str(),
	Printf, HashPtrToSeqNum);

	// Insert a print instruction for each instruction preceding InsertPos.
	// The print instructions must go before InsertPos, so we use the
	// instruction preceding InsertPos to check when to terminate the loop.
	//
	if (InsertPos != BB->begin()) { // there's at least one instr before InsertPos
	BasicBlock::iterator II = BB->begin(), IEincl = InsertPos;
	--IEincl;
	do { // do from II up to IEincl, inclusive
	if (StoreInst SI = dyn_cast<StoreInst>(&II)) {
	assert(valuesStoredInFunction &&
	"Should not be printing a store instruction at function exit");
	LoadInst *LI = new LoadInst(SI->getPointerOperand(), SI->copyIndices(),
	"reload."+SI->getPointerOperand()->getName());
	InsertPos = ++BB->getInstList().insert(InsertPos, LI);
	valuesStoredInFunction->push_back(LI);
	}
	if (ShouldTraceValue(II))
	InsertVerbosePrintInst(II, BB, InsertPos, " ", Printf,HashPtrToSeqNum);
	} while (II++ != IEincl);
	}
	}

	static inline void InsertCodeToShowFunctionEntry(Function &F, Function *Printf,
	Function* HashPtrToSeqNum){
	// Get an iterator to point to the insertion location
	BasicBlock &BB = F.getEntryNode();
	BasicBlock::iterator BBI = BB.begin();

	std::ostringstream OutStr;
	WriteAsOperand(OutStr, &F, true);
	InsertPrintInst(0, &BB, BBI, "ENTERING FUNCTION: " + OutStr.str(),
	Printf, HashPtrToSeqNum);

	// Now print all the incoming arguments
	unsigned ArgNo = 0;
	for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I, ++ArgNo){
	InsertVerbosePrintInst(I, &BB, BBI,
	" Arg #" + utostr(ArgNo) + ": ", Printf,
	HashPtrToSeqNum);
	}
	}


	static inline void InsertCodeToShowFunctionExit(BasicBlock *BB,
	Function *Printf,
	Function* HashPtrToSeqNum) {
	// Get an iterator to point to the insertion location
	BasicBlock::iterator BBI = --BB->end();
	ReturnInst &Ret = cast<ReturnInst>(BB->back());

	std::ostringstream OutStr;
	WriteAsOperand(OutStr, BB->getParent(), true);
	InsertPrintInst(0, BB, BBI, "LEAVING FUNCTION: " + OutStr.str(),
	Printf, HashPtrToSeqNum);

	// print the return value, if any
	if (BB->getParent()->getReturnType() != Type::VoidTy)
	InsertPrintInst(Ret.getReturnValue(), BB, BBI, " Returning: ",
	Printf, HashPtrToSeqNum);
	}


	bool InsertTraceCode::runOnFunction(Function &F) {
	if (!TraceThisFunction(F))
	return false;

	vector<Instruction*> valuesStoredInFunction;
	vector<BasicBlock*> exitBlocks;

	// Insert code to trace values at function entry
	InsertCodeToShowFunctionEntry(F, externalFuncs.PrintfFunc,
	externalFuncs.HashPtrFunc);

	// Push a pointer set for recording alloca'd pointers at entry.
	if (!DisablePtrHashing)
	InsertPushOnEntryFunc(&F, externalFuncs.PushOnEntryFunc);

	for (Function::iterator BB = F.begin(); BB != F.end(); ++BB) {
	if (isa<ReturnInst>(BB->getTerminator()))
	exitBlocks.push_back(BB); // record this as an exit block

	// Insert trace code if this basic block is interesting...
	handleBasicBlock(BB, valuesStoredInFunction);

	if (!DisablePtrHashing) // release seq. numbers on free/ret
	ReleasePtrSeqNumbers(BB, externalFuncs);
	}

	for (unsigned i=0; i != exitBlocks.size(); ++i)
	{
	// Insert code to trace values at function exit
	InsertCodeToShowFunctionExit(exitBlocks[i], externalFuncs.PrintfFunc,
	externalFuncs.HashPtrFunc);

	// Release all recorded pointers before RETURN. Do this LAST!
	if (!DisablePtrHashing)
	InsertReleaseRecordedInst(exitBlocks[i],
	externalFuncs.ReleaseOnReturnFunc);
	}

	return true;
	}