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

 //===- LevelRaise.cpp - Code to change LLVM to higher level -----------------=//
 //
 // This file implements the 'raising' part of the LevelChange API.  This is
 // useful because, in general, it makes the LLVM code terser and easier to
 // analyze.
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/Transforms/LevelChange.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include "TransformInternals.h"
 #include "llvm/iOther.h"
 #include "llvm/iMemory.h"
 #include "llvm/Pass.h"
 #include "llvm/ConstantHandling.h"
 #include "llvm/Analysis/Expressions.h"
 #include "llvm/Analysis/Verifier.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "Support/STLExtras.h"
 #include "Support/StatisticReporter.h"
 #include "Support/CommandLine.h"
 #include <algorithm>
 using std::cerr;

 // StartInst - This enables the -raise-start-inst=foo option to cause the level
 // raising pass to start at instruction "foo", which is immensely useful for
 // debugging!
 //
 static cl::opt<std::string>
 StartInst("raise-start-inst", cl::Hidden, cl::value_desc("inst name"),
        cl::desc("Start raise pass at the instruction with the specified name"));

 static Statistic<>
 NumLoadStorePeepholes("raise\t\t- Number of load/store peepholes");

 static Statistic<>
 NumGEPInstFormed("raise\t\t- Number of other getelementptr's formed");

 static Statistic<>
 NumExprTreesConv("raise\t\t- Number of expression trees converted");

 static Statistic<>
 NumCastOfCast("raise\t\t- Number of cast-of-self removed");

 static Statistic<>
 NumDCEorCP("raise\t\t- Number of insts DCEd or constprop'd");


 #define PRINT_PEEPHOLE(ID, NUM, I)            \
   DEBUG(std::cerr << "Inst P/H " << ID << "[" << NUM << "] " << I)

 #define PRINT_PEEPHOLE1(ID, I1) do { PRINT_PEEPHOLE(ID, 0, I1); } while (0)
 #define PRINT_PEEPHOLE2(ID, I1, I2) \
   do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); } while (0)
 #define PRINT_PEEPHOLE3(ID, I1, I2, I3) \
   do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); \
        PRINT_PEEPHOLE(ID, 2, I3); } while (0)
 #define PRINT_PEEPHOLE4(ID, I1, I2, I3, I4) \
   do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); \
        PRINT_PEEPHOLE(ID, 2, I3); PRINT_PEEPHOLE(ID, 3, I4); } while (0)


 // isReinterpretingCast - Return true if the cast instruction specified will
 // cause the operand to be "reinterpreted".  A value is reinterpreted if the
 // cast instruction would cause the underlying bits to change.
 //
 static inline bool isReinterpretingCast(const CastInst *CI) {
   return!CI->getOperand(0)->getType()->isLosslesslyConvertableTo(CI->getType());
 }


 // Peephole optimize the following instructions:
 // %t1 = cast ? to x *
 // %t2 = add x * %SP, %t1              ;; Constant must be 2nd operand
 //
 // Into: %t3 = getelementptr {<...>} * %SP, <element indices>
 //       %t2 = cast <eltype> * %t3 to {<...>}*
 //
 static bool HandleCastToPointer(BasicBlock::iterator BI,
                                 const PointerType *DestPTy) {
   CastInst &CI = cast<CastInst>(*BI);
   if (CI.use_empty()) return false;

   // Scan all of the uses, looking for any uses that are not add
   // instructions.  If we have non-adds, do not make this transformation.
   //
   for (Value::use_iterator I = CI.use_begin(), E = CI.use_end();
        I != E; ++I) {
     if (BinaryOperator *BO = dyn_cast<BinaryOperator>(*I)) {
       if (BO->getOpcode() != Instruction::Add ||
           // Avoid add sbyte* %X, %X cases...
           BO->getOperand(0) == BO->getOperand(1))
         return false;
     } else {
       return false;
     }
   }

   std::vector<Value*> Indices;
   Value *Src = CI.getOperand(0);
   const Type *Result = ConvertableToGEP(DestPTy, Src, Indices, &BI);
   if (Result == 0) return false;  // Not convertable...

   PRINT_PEEPHOLE2("cast-add-to-gep:in", Src, CI);

   // If we have a getelementptr capability... transform all of the
   // add instruction uses into getelementptr's.
   while (!CI.use_empty()) {
     BinaryOperator *I = cast<BinaryOperator>(*CI.use_begin());
     assert(I->getOpcode() == Instruction::Add && I->getNumOperands() == 2 &&
            "Use is not a valid add instruction!");

     // Get the value added to the cast result pointer...
     Value *OtherPtr = I->getOperand((I->getOperand(0) == &CI) ? 1 : 0);

     Instruction *GEP = new GetElementPtrInst(OtherPtr, Indices, I->getName());
     PRINT_PEEPHOLE1("cast-add-to-gep:i", I);

     if (GEP->getType() == I->getType()) {
       // Replace the old add instruction with the shiny new GEP inst
       ReplaceInstWithInst(I, GEP);
     } else {
       // If the type produced by the gep instruction differs from the original
       // add instruction type, insert a cast now.
       //

       // Insert the GEP instruction before the old add instruction...
       I->getParent()->getInstList().insert(I, GEP);

       PRINT_PEEPHOLE1("cast-add-to-gep:o", GEP);
       GEP = new CastInst(GEP, I->getType());

       // Replace the old add instruction with the shiny new GEP inst
       ReplaceInstWithInst(I, GEP);
     }

     PRINT_PEEPHOLE1("cast-add-to-gep:o", GEP);
   }
   return true;
 }

 // Peephole optimize the following instructions:
 // %t1 = cast ulong <const int> to {<...>} *
 // %t2 = add {<...>} * %SP, %t1              ;; Constant must be 2nd operand
 //
 //    or
 // %t1 = cast {<...>}* %SP to int*
 // %t5 = cast ulong <const int> to int*
 // %t2 = add int* %t1, %t5                   ;; int is same size as field
 //
 // Into: %t3 = getelementptr {<...>} * %SP, <element indices>
 //       %t2 = cast <eltype> * %t3 to {<...>}*
 //
 static bool PeepholeOptimizeAddCast(BasicBlock *BB, BasicBlock::iterator &BI,
                                     Value *AddOp1, CastInst *AddOp2) {
   const CompositeType *CompTy;
   Value *OffsetVal = AddOp2->getOperand(0);
   Value *SrcPtr;  // Of type pointer to struct...

   if ((CompTy = getPointedToComposite(AddOp1->getType()))) {
     SrcPtr = AddOp1;                      // Handle the first case...
   } else if (CastInst *AddOp1c = dyn_cast<CastInst>(AddOp1)) {
     SrcPtr = AddOp1c->getOperand(0);      // Handle the second case...
     CompTy = getPointedToComposite(SrcPtr->getType());
   }

   // Only proceed if we have detected all of our conditions successfully...
   if (!CompTy || !SrcPtr || !OffsetVal->getType()->isIntegral())
     return false;

   std::vector<Value*> Indices;
   if (!ConvertableToGEP(SrcPtr->getType(), OffsetVal, Indices, &BI))
     return false;  // Not convertable... perhaps next time

   if (getPointedToComposite(AddOp1->getType())) {  // case 1
     PRINT_PEEPHOLE2("add-to-gep1:in", AddOp2, *BI);
   } else {
     PRINT_PEEPHOLE3("add-to-gep2:in", AddOp1, AddOp2, *BI);
   }

   GetElementPtrInst *GEP = new GetElementPtrInst(SrcPtr, Indices,
                                                  AddOp2->getName());
   BI = ++BB->getInstList().insert(BI, GEP);

   Instruction *NCI = new CastInst(GEP, AddOp1->getType());
   ReplaceInstWithInst(BB->getInstList(), BI, NCI);
   PRINT_PEEPHOLE2("add-to-gep:out", GEP, NCI);
   return true;
 }

 static bool PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI) {
   Instruction *I = BI;

   if (CastInst *CI = dyn_cast<CastInst>(I)) {
     Value       *Src    = CI->getOperand(0);
     Instruction *SrcI   = dyn_cast<Instruction>(Src); // Nonnull if instr source
     const Type  *DestTy = CI->getType();

     // Peephole optimize the following instruction:
     // %V2 = cast <ty> %V to <ty>
     //
     // Into: <nothing>
     //
     if (DestTy == Src->getType()) {   // Check for a cast to same type as src!!
       PRINT_PEEPHOLE1("cast-of-self-ty", CI);
       CI->replaceAllUsesWith(Src);
       if (!Src->hasName() && CI->hasName()) {
         std::string Name = CI->getName();
         CI->setName("");
         Src->setName(Name, BB->getParent()->getSymbolTable());
       }

       // DCE the instruction now, to avoid having the iterative version of DCE
       // have to worry about it.
       //
       BI = BB->getInstList().erase(BI);

       ++NumCastOfCast;
       return true;
     }

     // Check to see if it's a cast of an instruction that does not depend on the
     // specific type of the operands to do it's job.
     if (!isReinterpretingCast(CI)) {
       ValueTypeCache ConvertedTypes;

       // Check to see if we can convert the source of the cast to match the
       // destination type of the cast...
       //
       ConvertedTypes[CI] = CI->getType();  // Make sure the cast doesn't change
       if (ExpressionConvertableToType(Src, DestTy, ConvertedTypes)) {
         PRINT_PEEPHOLE3("CAST-SRC-EXPR-CONV:in ", Src, CI, BB->getParent());

         DEBUG(cerr << "\nCONVERTING SRC EXPR TYPE:\n");
         { // ValueMap must be destroyed before function verified!
           ValueMapCache ValueMap;
           Value *E = ConvertExpressionToType(Src, DestTy, ValueMap);

           if (Constant *CPV = dyn_cast<Constant>(E))
             CI->replaceAllUsesWith(CPV);

           PRINT_PEEPHOLE1("CAST-SRC-EXPR-CONV:out", E);
           DEBUG(cerr << "DONE CONVERTING SRC EXPR TYPE: \n" << BB->getParent());
         }

         DEBUG(assert(verifyFunction(*BB->getParent()) == false &&
                      "Function broken!"));
         BI = BB->begin();  // Rescan basic block.  BI might be invalidated.
         ++NumExprTreesConv;
         return true;
       }

       // Check to see if we can convert the users of the cast value to match the
       // source type of the cast...
       //
       ConvertedTypes.clear();
       ConvertedTypes[Src] = Src->getType();  // Make sure the source doesn't change type
       if (ValueConvertableToType(CI, Src->getType(), ConvertedTypes)) {
         PRINT_PEEPHOLE3("CAST-DEST-EXPR-CONV:in ", Src, CI, BB->getParent());

         DEBUG(cerr << "\nCONVERTING EXPR TYPE:\n");
         { // ValueMap must be destroyed before function verified!
           ValueMapCache ValueMap;
           ConvertValueToNewType(CI, Src, ValueMap);  // This will delete CI!
         }

         PRINT_PEEPHOLE1("CAST-DEST-EXPR-CONV:out", Src);
         DEBUG(cerr << "DONE CONVERTING EXPR TYPE: \n\n" << BB->getParent());

         DEBUG(assert(verifyFunction(*BB->getParent()) == false &&
                      "Function broken!"));
         BI = BB->begin();  // Rescan basic block.  BI might be invalidated.
         ++NumExprTreesConv;
         return true;
       }
     }

     // Otherwise find out it this cast is a cast to a pointer type, which is
     // then added to some other pointer, then loaded or stored through.  If
     // so, convert the add into a getelementptr instruction...
     //
     if (const PointerType *DestPTy = dyn_cast<PointerType>(DestTy)) {
       if (HandleCastToPointer(BI, DestPTy)) {
         BI = BB->begin();  // Rescan basic block.  BI might be invalidated.
         ++NumGEPInstFormed;
         return true;
       }
     }

     // Check to see if we are casting from a structure pointer to a pointer to
     // the first element of the structure... to avoid munching other peepholes,
     // we only let this happen if there are no add uses of the cast.
     //
     // Peephole optimize the following instructions:
     // %t1 = cast {<...>} * %StructPtr to <ty> *
     //
     // Into: %t2 = getelementptr {<...>} * %StructPtr, <0, 0, 0, ...>
     //       %t1 = cast <eltype> * %t1 to <ty> *
     //
     if (const CompositeType *CTy = getPointedToComposite(Src->getType()))
       if (const PointerType *DestPTy = dyn_cast<PointerType>(DestTy)) {

         // Loop over uses of the cast, checking for add instructions.  If an add
         // exists, this is probably a part of a more complex GEP, so we don't
         // want to mess around with the cast.
         //
         bool HasAddUse = false;
         for (Value::use_iterator I = CI->use_begin(), E = CI->use_end();
              I != E; ++I)
           if (isa<Instruction>(*I) &&
               cast<Instruction>(*I)->getOpcode() == Instruction::Add) {
             HasAddUse = true; break;
           }

         // If it doesn't have an add use, check to see if the dest type is
         // losslessly convertable to one of the types in the start of the struct
         // type.
         //
         if (!HasAddUse) {
           const Type *DestPointedTy = DestPTy->getElementType();
           unsigned Depth = 1;
           const CompositeType *CurCTy = CTy;
           const Type *ElTy = 0;

           // Build the index vector, full of all zeros
           std::vector<Value*> Indices;
           Indices.push_back(ConstantUInt::get(Type::UIntTy, 0));
           while (CurCTy && !isa<PointerType>(CurCTy)) {
             if (const StructType *CurSTy = dyn_cast<StructType>(CurCTy)) {
               // Check for a zero element struct type... if we have one, bail.
               if (CurSTy->getElementTypes().size() == 0) break;

               // Grab the first element of the struct type, which must lie at
               // offset zero in the struct.
               //
               ElTy = CurSTy->getElementTypes()[0];
             } else {
               ElTy = cast<ArrayType>(CurCTy)->getElementType();
             }

             // Insert a zero to index through this type...
             Indices.push_back(ConstantUInt::get(CurCTy->getIndexType(), 0));

             // Did we find what we're looking for?
             if (ElTy->isLosslesslyConvertableTo(DestPointedTy)) break;

             // Nope, go a level deeper.
             ++Depth;
             CurCTy = dyn_cast<CompositeType>(ElTy);
             ElTy = 0;
           }

           // Did we find what we were looking for? If so, do the transformation
           if (ElTy) {
             PRINT_PEEPHOLE1("cast-for-first:in", CI);

             // Insert the new T cast instruction... stealing old T's name
             GetElementPtrInst *GEP = new GetElementPtrInst(Src, Indices,
                                                            CI->getName());
             CI->setName("");
             BI = ++BB->getInstList().insert(BI, GEP);

             // Make the old cast instruction reference the new GEP instead of
             // the old src value.
             //
             CI->setOperand(0, GEP);

             PRINT_PEEPHOLE2("cast-for-first:out", GEP, CI);
             ++NumGEPInstFormed;
             return true;
           }
         }
       }

   } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
     Value *Val     = SI->getOperand(0);
     Value *Pointer = SI->getPointerOperand();

     // Peephole optimize the following instructions:
     // %t = cast <T1>* %P to <T2> * ;; If T1 is losslessly convertable to T2
     // store <T2> %V, <T2>* %t
     //
     // Into:
     // %t = cast <T2> %V to <T1>
     // store <T1> %t2, <T1>* %P
     //
     // Note: This is not taken care of by expr conversion because there might
     // not be a cast available for the store to convert the incoming value of.
     // This code is basically here to make sure that pointers don't have casts
     // if possible.
     //
     if (CastInst *CI = dyn_cast<CastInst>(Pointer))
       if (Value *CastSrc = CI->getOperand(0)) // CSPT = CastSrcPointerType
         if (const PointerType *CSPT = dyn_cast<PointerType>(CastSrc->getType()))
           // convertable types?
           if (Val->getType()->isLosslesslyConvertableTo(CSPT->getElementType()) &&
               !SI->hasIndices()) {      // No subscripts yet!
             PRINT_PEEPHOLE3("st-src-cast:in ", Pointer, Val, SI);

             // Insert the new T cast instruction... stealing old T's name
             CastInst *NCI = new CastInst(Val, CSPT->getElementType(),
                                          CI->getName());
             CI->setName("");
             BI = ++BB->getInstList().insert(BI, NCI);

             // Replace the old store with a new one!
             ReplaceInstWithInst(BB->getInstList(), BI,
                                 SI = new StoreInst(NCI, CastSrc));
             PRINT_PEEPHOLE3("st-src-cast:out", NCI, CastSrc, SI);
             ++NumLoadStorePeepholes;
             return true;
           }

   } else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
     Value *Pointer = LI->getOperand(0);
     const Type *PtrElType =
       cast<PointerType>(Pointer->getType())->getElementType();

     // Peephole optimize the following instructions:
     // %Val = cast <T1>* to <T2>*    ;; If T1 is losslessly convertable to T2
     // %t = load <T2>* %P
     //
     // Into:
     // %t = load <T1>* %P
     // %Val = cast <T1> to <T2>
     //
     // Note: This is not taken care of by expr conversion because there might
     // not be a cast available for the store to convert the incoming value of.
     // This code is basically here to make sure that pointers don't have casts
     // if possible.
     //
     if (CastInst *CI = dyn_cast<CastInst>(Pointer))
       if (Value *CastSrc = CI->getOperand(0)) // CSPT = CastSrcPointerType
         if (const PointerType *CSPT = dyn_cast<PointerType>(CastSrc->getType()))
           // convertable types?
           if (PtrElType->isLosslesslyConvertableTo(CSPT->getElementType()) &&
               !LI->hasIndices()) {      // No subscripts yet!
             PRINT_PEEPHOLE2("load-src-cast:in ", Pointer, LI);

             // Create the new load instruction... loading the pre-casted value
             LoadInst *NewLI = new LoadInst(CastSrc, LI->getName());

             // Insert the new T cast instruction... stealing old T's name
             CastInst *NCI = new CastInst(NewLI, LI->getType(), CI->getName());
             BI = ++BB->getInstList().insert(BI, NewLI);

             // Replace the old store with a new one!
             ReplaceInstWithInst(BB->getInstList(), BI, NCI);
             PRINT_PEEPHOLE3("load-src-cast:out", NCI, CastSrc, NewLI);
             ++NumLoadStorePeepholes;
             return true;
           }

   } else if (I->getOpcode() == Instruction::Add &&
              isa<CastInst>(I->getOperand(1))) {

     if (PeepholeOptimizeAddCast(BB, BI, I->getOperand(0),
                                 cast<CastInst>(I->getOperand(1)))) {
       ++NumGEPInstFormed;
       return true;
     }
   }

   return false;
 }


 static bool DoRaisePass(Function &F) {
   bool Changed = false;
   for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB)
     for (BasicBlock::iterator BI = BB->begin(); BI != BB->end();) {
       DEBUG(cerr << "Processing: " << *BI);
       if (dceInstruction(BI) || doConstantPropogation(BI)) {
         Changed = true;
         ++NumDCEorCP;
         DEBUG(cerr << "***\t\t^^-- DeadCode Elinated!\n");
       } else if (PeepholeOptimize(BB, BI)) {
         Changed = true;
       } else {
         ++BI;
       }
     }

   return Changed;
 }


 // RaisePointerReferences::doit - Raise a function representation to a higher
 // level.
 //
 static bool doRPR(Function &F) {
   DEBUG(cerr << "\n\n\nStarting to work on Function '" << F.getName() << "'\n");

   // Insert casts for all incoming pointer pointer values that are treated as
   // arrays...
   //
   bool Changed = false, LocalChange;


   // If the StartInst option was specified, then Peephole optimize that
   // instruction first if it occurs in this function.
   //
   if (!StartInst.empty()) {
     for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB)
       for (BasicBlock::iterator BI = BB->begin(); BI != BB->end(); ++BI)
         if (BI->getName() == StartInst) {
           bool SavedDebug = DebugFlag;  // Save the DEBUG() controlling flag.
           DebugFlag = true;             // Turn on DEBUG's
           Changed |= PeepholeOptimize(BB, BI);
           DebugFlag = SavedDebug;       // Restore DebugFlag to previous state
         }
   }

   do {
     DEBUG(cerr << "Looping: \n" << F);

     // Iterate over the function, refining it, until it converges on a stable
     // state
     LocalChange = false;
     while (DoRaisePass(F)) LocalChange = true;
     Changed |= LocalChange;

   } while (LocalChange);

   return Changed;
 }

 namespace {
   struct RaisePointerReferences : public FunctionPass {
     const char *getPassName() const { return "Raise Pointer References"; }

     virtual bool runOnFunction(Function &F) { return doRPR(F); }

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

 Pass *createRaisePointerReferencesPass() {
   return new RaisePointerReferences();
 }
	//===- LevelRaise.cpp - Code to change LLVM to higher level -----------------=//
	//
	// This file implements the 'raising' part of the LevelChange API. This is
	// useful because, in general, it makes the LLVM code terser and easier to
	// analyze.
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/Transforms/LevelChange.h"
	#include "llvm/Transforms/Utils/Local.h"
	#include "TransformInternals.h"
	#include "llvm/iOther.h"
	#include "llvm/iMemory.h"
	#include "llvm/Pass.h"
	#include "llvm/ConstantHandling.h"
	#include "llvm/Analysis/Expressions.h"
	#include "llvm/Analysis/Verifier.h"
	#include "llvm/Transforms/Utils/BasicBlockUtils.h"
	#include "Support/STLExtras.h"
	#include "Support/StatisticReporter.h"
	#include "Support/CommandLine.h"
	#include <algorithm>
	using std::cerr;

	// StartInst - This enables the -raise-start-inst=foo option to cause the level
	// raising pass to start at instruction "foo", which is immensely useful for
	// debugging!
	//
	static cl::opt<std::string>
	StartInst("raise-start-inst", cl::Hidden, cl::value_desc("inst name"),
	cl::desc("Start raise pass at the instruction with the specified name"));

	static Statistic<>
	NumLoadStorePeepholes("raise\t\t- Number of load/store peepholes");

	static Statistic<>
	NumGEPInstFormed("raise\t\t- Number of other getelementptr's formed");

	static Statistic<>
	NumExprTreesConv("raise\t\t- Number of expression trees converted");

	static Statistic<>
	NumCastOfCast("raise\t\t- Number of cast-of-self removed");

	static Statistic<>
	NumDCEorCP("raise\t\t- Number of insts DCEd or constprop'd");


	#define PRINT_PEEPHOLE(ID, NUM, I) \
	DEBUG(std::cerr << "Inst P/H " << ID << "[" << NUM << "] " << I)

	#define PRINT_PEEPHOLE1(ID, I1) do { PRINT_PEEPHOLE(ID, 0, I1); } while (0)
	#define PRINT_PEEPHOLE2(ID, I1, I2) \
	do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); } while (0)
	#define PRINT_PEEPHOLE3(ID, I1, I2, I3) \
	do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); \
	PRINT_PEEPHOLE(ID, 2, I3); } while (0)
	#define PRINT_PEEPHOLE4(ID, I1, I2, I3, I4) \
	do { PRINT_PEEPHOLE(ID, 0, I1); PRINT_PEEPHOLE(ID, 1, I2); \
	PRINT_PEEPHOLE(ID, 2, I3); PRINT_PEEPHOLE(ID, 3, I4); } while (0)


	// isReinterpretingCast - Return true if the cast instruction specified will
	// cause the operand to be "reinterpreted". A value is reinterpreted if the
	// cast instruction would cause the underlying bits to change.
	//
	static inline bool isReinterpretingCast(const CastInst *CI) {
	return!CI->getOperand(0)->getType()->isLosslesslyConvertableTo(CI->getType());
	}


	// Peephole optimize the following instructions:
	// %t1 = cast ? to x *
	// %t2 = add x * %SP, %t1 ;; Constant must be 2nd operand
	//
	// Into: %t3 = getelementptr {<...>} * %SP, <element indices>
	// %t2 = cast <eltype> * %t3 to {<...>}*
	//
	static bool HandleCastToPointer(BasicBlock::iterator BI,
	const PointerType *DestPTy) {
	CastInst &CI = cast<CastInst>(*BI);
	if (CI.use_empty()) return false;

	// Scan all of the uses, looking for any uses that are not add
	// instructions. If we have non-adds, do not make this transformation.
	//
	for (Value::use_iterator I = CI.use_begin(), E = CI.use_end();
	I != E; ++I) {
	if (BinaryOperator BO = dyn_cast<BinaryOperator>(I)) {
	if (BO->getOpcode() != Instruction::Add \|\|
	// Avoid add sbyte* %X, %X cases...
	BO->getOperand(0) == BO->getOperand(1))
	return false;
	} else {
	return false;
	}
	}

	std::vector<Value*> Indices;
	Value *Src = CI.getOperand(0);
	const Type *Result = ConvertableToGEP(DestPTy, Src, Indices, &BI);
	if (Result == 0) return false; // Not convertable...

	PRINT_PEEPHOLE2("cast-add-to-gep:in", Src, CI);

	// If we have a getelementptr capability... transform all of the
	// add instruction uses into getelementptr's.
	while (!CI.use_empty()) {
	BinaryOperator I = cast<BinaryOperator>(CI.use_begin());
	assert(I->getOpcode() == Instruction::Add && I->getNumOperands() == 2 &&
	"Use is not a valid add instruction!");

	// Get the value added to the cast result pointer...
	Value *OtherPtr = I->getOperand((I->getOperand(0) == &CI) ? 1 : 0);

	Instruction *GEP = new GetElementPtrInst(OtherPtr, Indices, I->getName());
	PRINT_PEEPHOLE1("cast-add-to-gep:i", I);

	if (GEP->getType() == I->getType()) {
	// Replace the old add instruction with the shiny new GEP inst
	ReplaceInstWithInst(I, GEP);
	} else {
	// If the type produced by the gep instruction differs from the original
	// add instruction type, insert a cast now.
	//

	// Insert the GEP instruction before the old add instruction...
	I->getParent()->getInstList().insert(I, GEP);

	PRINT_PEEPHOLE1("cast-add-to-gep:o", GEP);
	GEP = new CastInst(GEP, I->getType());

	// Replace the old add instruction with the shiny new GEP inst
	ReplaceInstWithInst(I, GEP);
	}

	PRINT_PEEPHOLE1("cast-add-to-gep:o", GEP);
	}
	return true;
	}

	// Peephole optimize the following instructions:
	// %t1 = cast ulong <const int> to {<...>} *
	// %t2 = add {<...>} * %SP, %t1 ;; Constant must be 2nd operand
	//
	// or
	// %t1 = cast {<...>}* %SP to int*
	// %t5 = cast ulong <const int> to int*
	// %t2 = add int* %t1, %t5 ;; int is same size as field
	//
	// Into: %t3 = getelementptr {<...>} * %SP, <element indices>
	// %t2 = cast <eltype> * %t3 to {<...>}*
	//
	static bool PeepholeOptimizeAddCast(BasicBlock *BB, BasicBlock::iterator &BI,
	Value AddOp1, CastInst AddOp2) {
	const CompositeType *CompTy;
	Value *OffsetVal = AddOp2->getOperand(0);
	Value *SrcPtr; // Of type pointer to struct...

	if ((CompTy = getPointedToComposite(AddOp1->getType()))) {
	SrcPtr = AddOp1; // Handle the first case...
	} else if (CastInst *AddOp1c = dyn_cast<CastInst>(AddOp1)) {
	SrcPtr = AddOp1c->getOperand(0); // Handle the second case...
	CompTy = getPointedToComposite(SrcPtr->getType());
	}

	// Only proceed if we have detected all of our conditions successfully...
	if (!CompTy \|\| !SrcPtr \|\| !OffsetVal->getType()->isIntegral())
	return false;

	std::vector<Value*> Indices;
	if (!ConvertableToGEP(SrcPtr->getType(), OffsetVal, Indices, &BI))
	return false; // Not convertable... perhaps next time

	if (getPointedToComposite(AddOp1->getType())) { // case 1
	PRINT_PEEPHOLE2("add-to-gep1:in", AddOp2, *BI);
	} else {
	PRINT_PEEPHOLE3("add-to-gep2:in", AddOp1, AddOp2, *BI);
	}

	GetElementPtrInst *GEP = new GetElementPtrInst(SrcPtr, Indices,
	AddOp2->getName());
	BI = ++BB->getInstList().insert(BI, GEP);

	Instruction *NCI = new CastInst(GEP, AddOp1->getType());
	ReplaceInstWithInst(BB->getInstList(), BI, NCI);
	PRINT_PEEPHOLE2("add-to-gep:out", GEP, NCI);
	return true;
	}

	static bool PeepholeOptimize(BasicBlock *BB, BasicBlock::iterator &BI) {
	Instruction *I = BI;

	if (CastInst *CI = dyn_cast<CastInst>(I)) {
	Value *Src = CI->getOperand(0);
	Instruction *SrcI = dyn_cast<Instruction>(Src); // Nonnull if instr source
	const Type *DestTy = CI->getType();

	// Peephole optimize the following instruction:
	// %V2 = cast <ty> %V to <ty>
	//
	// Into: <nothing>
	//
	if (DestTy == Src->getType()) { // Check for a cast to same type as src!!
	PRINT_PEEPHOLE1("cast-of-self-ty", CI);
	CI->replaceAllUsesWith(Src);
	if (!Src->hasName() && CI->hasName()) {
	std::string Name = CI->getName();
	CI->setName("");
	Src->setName(Name, BB->getParent()->getSymbolTable());
	}

	// DCE the instruction now, to avoid having the iterative version of DCE
	// have to worry about it.
	//
	BI = BB->getInstList().erase(BI);

	++NumCastOfCast;
	return true;
	}

	// Check to see if it's a cast of an instruction that does not depend on the
	// specific type of the operands to do it's job.
	if (!isReinterpretingCast(CI)) {
	ValueTypeCache ConvertedTypes;

	// Check to see if we can convert the source of the cast to match the
	// destination type of the cast...
	//
	ConvertedTypes[CI] = CI->getType(); // Make sure the cast doesn't change
	if (ExpressionConvertableToType(Src, DestTy, ConvertedTypes)) {
	PRINT_PEEPHOLE3("CAST-SRC-EXPR-CONV:in ", Src, CI, BB->getParent());

	DEBUG(cerr << "\nCONVERTING SRC EXPR TYPE:\n");
	{ // ValueMap must be destroyed before function verified!
	ValueMapCache ValueMap;
	Value *E = ConvertExpressionToType(Src, DestTy, ValueMap);

	if (Constant *CPV = dyn_cast<Constant>(E))
	CI->replaceAllUsesWith(CPV);

	PRINT_PEEPHOLE1("CAST-SRC-EXPR-CONV:out", E);
	DEBUG(cerr << "DONE CONVERTING SRC EXPR TYPE: \n" << BB->getParent());
	}

	DEBUG(assert(verifyFunction(*BB->getParent()) == false &&
	"Function broken!"));
	BI = BB->begin(); // Rescan basic block. BI might be invalidated.
	++NumExprTreesConv;
	return true;
	}

	// Check to see if we can convert the users of the cast value to match the
	// source type of the cast...
	//
	ConvertedTypes.clear();
	ConvertedTypes[Src] = Src->getType(); // Make sure the source doesn't change type
	if (ValueConvertableToType(CI, Src->getType(), ConvertedTypes)) {
	PRINT_PEEPHOLE3("CAST-DEST-EXPR-CONV:in ", Src, CI, BB->getParent());

	DEBUG(cerr << "\nCONVERTING EXPR TYPE:\n");
	{ // ValueMap must be destroyed before function verified!
	ValueMapCache ValueMap;
	ConvertValueToNewType(CI, Src, ValueMap); // This will delete CI!
	}

	PRINT_PEEPHOLE1("CAST-DEST-EXPR-CONV:out", Src);
	DEBUG(cerr << "DONE CONVERTING EXPR TYPE: \n\n" << BB->getParent());

	DEBUG(assert(verifyFunction(*BB->getParent()) == false &&
	"Function broken!"));
	BI = BB->begin(); // Rescan basic block. BI might be invalidated.
	++NumExprTreesConv;
	return true;
	}
	}

	// Otherwise find out it this cast is a cast to a pointer type, which is
	// then added to some other pointer, then loaded or stored through. If
	// so, convert the add into a getelementptr instruction...
	//
	if (const PointerType *DestPTy = dyn_cast<PointerType>(DestTy)) {
	if (HandleCastToPointer(BI, DestPTy)) {
	BI = BB->begin(); // Rescan basic block. BI might be invalidated.
	++NumGEPInstFormed;
	return true;
	}
	}

	// Check to see if we are casting from a structure pointer to a pointer to
	// the first element of the structure... to avoid munching other peepholes,
	// we only let this happen if there are no add uses of the cast.
	//
	// Peephole optimize the following instructions:
	// %t1 = cast {<...>} * %StructPtr to <ty> *
	//
	// Into: %t2 = getelementptr {<...>} * %StructPtr, <0, 0, 0, ...>
	// %t1 = cast <eltype> * %t1 to <ty> *
	//
	if (const CompositeType *CTy = getPointedToComposite(Src->getType()))
	if (const PointerType *DestPTy = dyn_cast<PointerType>(DestTy)) {

	// Loop over uses of the cast, checking for add instructions. If an add
	// exists, this is probably a part of a more complex GEP, so we don't
	// want to mess around with the cast.
	//
	bool HasAddUse = false;
	for (Value::use_iterator I = CI->use_begin(), E = CI->use_end();
	I != E; ++I)
	if (isa<Instruction>(*I) &&
	cast<Instruction>(*I)->getOpcode() == Instruction::Add) {
	HasAddUse = true; break;
	}

	// If it doesn't have an add use, check to see if the dest type is
	// losslessly convertable to one of the types in the start of the struct
	// type.
	//
	if (!HasAddUse) {
	const Type *DestPointedTy = DestPTy->getElementType();
	unsigned Depth = 1;
	const CompositeType *CurCTy = CTy;
	const Type *ElTy = 0;

	// Build the index vector, full of all zeros
	std::vector<Value*> Indices;
	Indices.push_back(ConstantUInt::get(Type::UIntTy, 0));
	while (CurCTy && !isa<PointerType>(CurCTy)) {
	if (const StructType *CurSTy = dyn_cast<StructType>(CurCTy)) {
	// Check for a zero element struct type... if we have one, bail.
	if (CurSTy->getElementTypes().size() == 0) break;

	// Grab the first element of the struct type, which must lie at
	// offset zero in the struct.
	//
	ElTy = CurSTy->getElementTypes()[0];
	} else {
	ElTy = cast<ArrayType>(CurCTy)->getElementType();
	}

	// Insert a zero to index through this type...
	Indices.push_back(ConstantUInt::get(CurCTy->getIndexType(), 0));

	// Did we find what we're looking for?
	if (ElTy->isLosslesslyConvertableTo(DestPointedTy)) break;

	// Nope, go a level deeper.
	++Depth;
	CurCTy = dyn_cast<CompositeType>(ElTy);
	ElTy = 0;
	}

	// Did we find what we were looking for? If so, do the transformation
	if (ElTy) {
	PRINT_PEEPHOLE1("cast-for-first:in", CI);

	// Insert the new T cast instruction... stealing old T's name
	GetElementPtrInst *GEP = new GetElementPtrInst(Src, Indices,
	CI->getName());
	CI->setName("");
	BI = ++BB->getInstList().insert(BI, GEP);

	// Make the old cast instruction reference the new GEP instead of
	// the old src value.
	//
	CI->setOperand(0, GEP);

	PRINT_PEEPHOLE2("cast-for-first:out", GEP, CI);
	++NumGEPInstFormed;
	return true;
	}
	}
	}

	} else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
	Value *Val = SI->getOperand(0);
	Value *Pointer = SI->getPointerOperand();

	// Peephole optimize the following instructions:
	// %t = cast <T1>* %P to <T2> * ;; If T1 is losslessly convertable to T2
	// store <T2> %V, <T2>* %t
	//
	// Into:
	// %t = cast <T2> %V to <T1>
	// store <T1> %t2, <T1>* %P
	//
	// Note: This is not taken care of by expr conversion because there might
	// not be a cast available for the store to convert the incoming value of.
	// This code is basically here to make sure that pointers don't have casts
	// if possible.
	//
	if (CastInst *CI = dyn_cast<CastInst>(Pointer))
	if (Value *CastSrc = CI->getOperand(0)) // CSPT = CastSrcPointerType
	if (const PointerType *CSPT = dyn_cast<PointerType>(CastSrc->getType()))
	// convertable types?
	if (Val->getType()->isLosslesslyConvertableTo(CSPT->getElementType()) &&
	!SI->hasIndices()) { // No subscripts yet!
	PRINT_PEEPHOLE3("st-src-cast:in ", Pointer, Val, SI);

	// Insert the new T cast instruction... stealing old T's name
	CastInst *NCI = new CastInst(Val, CSPT->getElementType(),
	CI->getName());
	CI->setName("");
	BI = ++BB->getInstList().insert(BI, NCI);

	// Replace the old store with a new one!
	ReplaceInstWithInst(BB->getInstList(), BI,
	SI = new StoreInst(NCI, CastSrc));
	PRINT_PEEPHOLE3("st-src-cast:out", NCI, CastSrc, SI);
	++NumLoadStorePeepholes;
	return true;
	}

	} else if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
	Value *Pointer = LI->getOperand(0);
	const Type *PtrElType =
	cast<PointerType>(Pointer->getType())->getElementType();

	// Peephole optimize the following instructions:
	// %Val = cast <T1>* to <T2>* ;; If T1 is losslessly convertable to T2
	// %t = load <T2>* %P
	//
	// Into:
	// %t = load <T1>* %P
	// %Val = cast <T1> to <T2>
	//
	// Note: This is not taken care of by expr conversion because there might
	// not be a cast available for the store to convert the incoming value of.
	// This code is basically here to make sure that pointers don't have casts
	// if possible.
	//
	if (CastInst *CI = dyn_cast<CastInst>(Pointer))
	if (Value *CastSrc = CI->getOperand(0)) // CSPT = CastSrcPointerType
	if (const PointerType *CSPT = dyn_cast<PointerType>(CastSrc->getType()))
	// convertable types?
	if (PtrElType->isLosslesslyConvertableTo(CSPT->getElementType()) &&
	!LI->hasIndices()) { // No subscripts yet!
	PRINT_PEEPHOLE2("load-src-cast:in ", Pointer, LI);

	// Create the new load instruction... loading the pre-casted value
	LoadInst *NewLI = new LoadInst(CastSrc, LI->getName());

	// Insert the new T cast instruction... stealing old T's name
	CastInst *NCI = new CastInst(NewLI, LI->getType(), CI->getName());
	BI = ++BB->getInstList().insert(BI, NewLI);

	// Replace the old store with a new one!
	ReplaceInstWithInst(BB->getInstList(), BI, NCI);
	PRINT_PEEPHOLE3("load-src-cast:out", NCI, CastSrc, NewLI);
	++NumLoadStorePeepholes;
	return true;
	}

	} else if (I->getOpcode() == Instruction::Add &&
	isa<CastInst>(I->getOperand(1))) {

	if (PeepholeOptimizeAddCast(BB, BI, I->getOperand(0),
	cast<CastInst>(I->getOperand(1)))) {
	++NumGEPInstFormed;
	return true;
	}
	}

	return false;
	}




	static bool DoRaisePass(Function &F) {
	bool Changed = false;
	for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB)
	for (BasicBlock::iterator BI = BB->begin(); BI != BB->end();) {
	DEBUG(cerr << "Processing: " << *BI);
	if (dceInstruction(BI) \|\| doConstantPropogation(BI)) {
	Changed = true;
	++NumDCEorCP;
	DEBUG(cerr << "***\t\t^^-- DeadCode Elinated!\n");
	} else if (PeepholeOptimize(BB, BI)) {
	Changed = true;
	} else {
	++BI;
	}
	}

	return Changed;
	}


	// RaisePointerReferences::doit - Raise a function representation to a higher
	// level.
	//
	static bool doRPR(Function &F) {
	DEBUG(cerr << "\n\n\nStarting to work on Function '" << F.getName() << "'\n");

	// Insert casts for all incoming pointer pointer values that are treated as
	// arrays...
	//
	bool Changed = false, LocalChange;


	// If the StartInst option was specified, then Peephole optimize that
	// instruction first if it occurs in this function.
	//
	if (!StartInst.empty()) {
	for (Function::iterator BB = F.begin(), BBE = F.end(); BB != BBE; ++BB)
	for (BasicBlock::iterator BI = BB->begin(); BI != BB->end(); ++BI)
	if (BI->getName() == StartInst) {
	bool SavedDebug = DebugFlag; // Save the DEBUG() controlling flag.
	DebugFlag = true; // Turn on DEBUG's
	Changed \|= PeepholeOptimize(BB, BI);
	DebugFlag = SavedDebug; // Restore DebugFlag to previous state
	}
	}

	do {
	DEBUG(cerr << "Looping: \n" << F);

	// Iterate over the function, refining it, until it converges on a stable
	// state
	LocalChange = false;
	while (DoRaisePass(F)) LocalChange = true;
	Changed \|= LocalChange;

	} while (LocalChange);

	return Changed;
	}

	namespace {
	struct RaisePointerReferences : public FunctionPass {
	const char *getPassName() const { return "Raise Pointer References"; }

	virtual bool runOnFunction(Function &F) { return doRPR(F); }

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

	Pass *createRaisePointerReferencesPass() {
	return new RaisePointerReferences();
	}