third_party/LLVM/lib/Transforms/Utils/CloneFunction.cpp - SwiftShader - Git at Google

 //===- CloneFunction.cpp - Clone a function into another function ---------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file implements the CloneFunctionInto interface, which is used as the
 // low-level function cloner.  This is used by the CloneFunction and function
 // inliner to do the dirty work of copying the body of a function around.
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/Transforms/Utils/Cloning.h"
 #include "llvm/Constants.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/Instructions.h"
 #include "llvm/IntrinsicInst.h"
 #include "llvm/GlobalVariable.h"
 #include "llvm/Function.h"
 #include "llvm/LLVMContext.h"
 #include "llvm/Metadata.h"
 #include "llvm/Support/CFG.h"
 #include "llvm/Transforms/Utils/ValueMapper.h"
 #include "llvm/Analysis/ConstantFolding.h"
 #include "llvm/Analysis/DebugInfo.h"
 #include "llvm/ADT/SmallVector.h"
 #include <map>
 using namespace llvm;

 // CloneBasicBlock - See comments in Cloning.h
 BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB,
                                   ValueToValueMapTy &VMap,
                                   const Twine &NameSuffix, Function *F,
                                   ClonedCodeInfo *CodeInfo) {
   BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "", F);
   if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);

   bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;

   // Loop over all instructions, and copy them over.
   for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end();
        II != IE; ++II) {
     Instruction *NewInst = II->clone();
     if (II->hasName())
       NewInst->setName(II->getName()+NameSuffix);
     NewBB->getInstList().push_back(NewInst);
     VMap[II] = NewInst;                // Add instruction map to value.

     hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
     if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
       if (isa<ConstantInt>(AI->getArraySize()))
         hasStaticAllocas = true;
       else
         hasDynamicAllocas = true;
     }
   }

   if (CodeInfo) {
     CodeInfo->ContainsCalls          |= hasCalls;
     CodeInfo->ContainsUnwinds        |= isa<UnwindInst>(BB->getTerminator());
     CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
     CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
                                         BB != &BB->getParent()->getEntryBlock();
   }
   return NewBB;
 }

 // Clone OldFunc into NewFunc, transforming the old arguments into references to
 // VMap values.
 //
 void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
                              ValueToValueMapTy &VMap,
                              bool ModuleLevelChanges,
                              SmallVectorImpl<ReturnInst*> &Returns,
                              const char *NameSuffix, ClonedCodeInfo *CodeInfo) {
   assert(NameSuffix && "NameSuffix cannot be null!");

 #ifndef NDEBUG
   for (Function::const_arg_iterator I = OldFunc->arg_begin(),
        E = OldFunc->arg_end(); I != E; ++I)
     assert(VMap.count(I) && "No mapping from source argument specified!");
 #endif

   // Clone any attributes.
   if (NewFunc->arg_size() == OldFunc->arg_size())
     NewFunc->copyAttributesFrom(OldFunc);
   else {
     //Some arguments were deleted with the VMap. Copy arguments one by one
     for (Function::const_arg_iterator I = OldFunc->arg_begin(),
            E = OldFunc->arg_end(); I != E; ++I)
       if (Argument* Anew = dyn_cast<Argument>(VMap[I]))
         Anew->addAttr( OldFunc->getAttributes()
                        .getParamAttributes(I->getArgNo() + 1));
     NewFunc->setAttributes(NewFunc->getAttributes()
                            .addAttr(0, OldFunc->getAttributes()
                                      .getRetAttributes()));
     NewFunc->setAttributes(NewFunc->getAttributes()
                            .addAttr(~0, OldFunc->getAttributes()
                                      .getFnAttributes()));

   }

   // Loop over all of the basic blocks in the function, cloning them as
   // appropriate.  Note that we save BE this way in order to handle cloning of
   // recursive functions into themselves.
   //
   for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
        BI != BE; ++BI) {
     const BasicBlock &BB = *BI;

     // Create a new basic block and copy instructions into it!
     BasicBlock *CBB = CloneBasicBlock(&BB, VMap, NameSuffix, NewFunc, CodeInfo);
     VMap[&BB] = CBB;                       // Add basic block mapping.

     if (ReturnInst *RI = dyn_cast<ReturnInst>(CBB->getTerminator()))
       Returns.push_back(RI);
   }

   // Loop over all of the instructions in the function, fixing up operand
   // references as we go.  This uses VMap to do all the hard work.
   for (Function::iterator BB = cast<BasicBlock>(VMap[OldFunc->begin()]),
          BE = NewFunc->end(); BB != BE; ++BB)
     // Loop over all instructions, fixing each one as we find it...
     for (BasicBlock::iterator II = BB->begin(); II != BB->end(); ++II)
       RemapInstruction(II, VMap,
                        ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
 }

 /// CloneFunction - Return a copy of the specified function, but without
 /// embedding the function into another module.  Also, any references specified
 /// in the VMap are changed to refer to their mapped value instead of the
 /// original one.  If any of the arguments to the function are in the VMap,
 /// the arguments are deleted from the resultant function.  The VMap is
 /// updated to include mappings from all of the instructions and basicblocks in
 /// the function from their old to new values.
 ///
 Function *llvm::CloneFunction(const Function *F, ValueToValueMapTy &VMap,
                               bool ModuleLevelChanges,
                               ClonedCodeInfo *CodeInfo) {
   std::vector<Type*> ArgTypes;

   // The user might be deleting arguments to the function by specifying them in
   // the VMap.  If so, we need to not add the arguments to the arg ty vector
   //
   for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
        I != E; ++I)
     if (VMap.count(I) == 0)  // Haven't mapped the argument to anything yet?
       ArgTypes.push_back(I->getType());

   // Create a new function type...
   FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(),
                                     ArgTypes, F->getFunctionType()->isVarArg());

   // Create the new function...
   Function *NewF = Function::Create(FTy, F->getLinkage(), F->getName());

   // Loop over the arguments, copying the names of the mapped arguments over...
   Function::arg_iterator DestI = NewF->arg_begin();
   for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
        I != E; ++I)
     if (VMap.count(I) == 0) {   // Is this argument preserved?
       DestI->setName(I->getName()); // Copy the name over...
       VMap[I] = DestI++;        // Add mapping to VMap
     }

   SmallVector<ReturnInst*, 8> Returns;  // Ignore returns cloned.
   CloneFunctionInto(NewF, F, VMap, ModuleLevelChanges, Returns, "", CodeInfo);
   return NewF;
 }


 namespace {
   /// PruningFunctionCloner - This class is a private class used to implement
   /// the CloneAndPruneFunctionInto method.
   struct PruningFunctionCloner {
     Function *NewFunc;
     const Function *OldFunc;
     ValueToValueMapTy &VMap;
     bool ModuleLevelChanges;
     SmallVectorImpl<ReturnInst*> &Returns;
     const char *NameSuffix;
     ClonedCodeInfo *CodeInfo;
     const TargetData *TD;
   public:
     PruningFunctionCloner(Function *newFunc, const Function *oldFunc,
                           ValueToValueMapTy &valueMap,
                           bool moduleLevelChanges,
                           SmallVectorImpl<ReturnInst*> &returns,
                           const char *nameSuffix,
                           ClonedCodeInfo *codeInfo,
                           const TargetData *td)
     : NewFunc(newFunc), OldFunc(oldFunc),
       VMap(valueMap), ModuleLevelChanges(moduleLevelChanges),
       Returns(returns), NameSuffix(nameSuffix), CodeInfo(codeInfo), TD(td) {
     }

     /// CloneBlock - The specified block is found to be reachable, clone it and
     /// anything that it can reach.
     void CloneBlock(const BasicBlock *BB,
                     std::vector<const BasicBlock*> &ToClone);

   public:
     /// ConstantFoldMappedInstruction - Constant fold the specified instruction,
     /// mapping its operands through VMap if they are available.
     Constant *ConstantFoldMappedInstruction(const Instruction *I);
   };
 }

 /// CloneBlock - The specified block is found to be reachable, clone it and
 /// anything that it can reach.
 void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
                                        std::vector<const BasicBlock*> &ToClone){
   TrackingVH<Value> &BBEntry = VMap[BB];

   // Have we already cloned this block?
   if (BBEntry) return;

   // Nope, clone it now.
   BasicBlock *NewBB;
   BBEntry = NewBB = BasicBlock::Create(BB->getContext());
   if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);

   bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;

   // Loop over all instructions, and copy them over, DCE'ing as we go.  This
   // loop doesn't include the terminator.
   for (BasicBlock::const_iterator II = BB->begin(), IE = --BB->end();
        II != IE; ++II) {
     // If this instruction constant folds, don't bother cloning the instruction,
     // instead, just add the constant to the value map.
     if (Constant *C = ConstantFoldMappedInstruction(II)) {
       VMap[II] = C;
       continue;
     }

     Instruction *NewInst = II->clone();
     if (II->hasName())
       NewInst->setName(II->getName()+NameSuffix);
     NewBB->getInstList().push_back(NewInst);
     VMap[II] = NewInst;                // Add instruction map to value.

     hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
     if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
       if (isa<ConstantInt>(AI->getArraySize()))
         hasStaticAllocas = true;
       else
         hasDynamicAllocas = true;
     }
   }

   // Finally, clone over the terminator.
   const TerminatorInst *OldTI = BB->getTerminator();
   bool TerminatorDone = false;
   if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
     if (BI->isConditional()) {
       // If the condition was a known constant in the callee...
       ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
       // Or is a known constant in the caller...
       if (Cond == 0) {
         Value *V = VMap[BI->getCondition()];
         Cond = dyn_cast_or_null<ConstantInt>(V);
       }

       // Constant fold to uncond branch!
       if (Cond) {
         BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue());
         VMap[OldTI] = BranchInst::Create(Dest, NewBB);
         ToClone.push_back(Dest);
         TerminatorDone = true;
       }
     }
   } else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
     // If switching on a value known constant in the caller.
     ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
     if (Cond == 0) { // Or known constant after constant prop in the callee...
       Value *V = VMap[SI->getCondition()];
       Cond = dyn_cast_or_null<ConstantInt>(V);
     }
     if (Cond) {     // Constant fold to uncond branch!
       BasicBlock *Dest = SI->getSuccessor(SI->findCaseValue(Cond));
       VMap[OldTI] = BranchInst::Create(Dest, NewBB);
       ToClone.push_back(Dest);
       TerminatorDone = true;
     }
   }

   if (!TerminatorDone) {
     Instruction *NewInst = OldTI->clone();
     if (OldTI->hasName())
       NewInst->setName(OldTI->getName()+NameSuffix);
     NewBB->getInstList().push_back(NewInst);
     VMap[OldTI] = NewInst;             // Add instruction map to value.

     // Recursively clone any reachable successor blocks.
     const TerminatorInst *TI = BB->getTerminator();
     for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
       ToClone.push_back(TI->getSuccessor(i));
   }

   if (CodeInfo) {
     CodeInfo->ContainsCalls          |= hasCalls;
     CodeInfo->ContainsUnwinds        |= isa<UnwindInst>(OldTI);
     CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
     CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
       BB != &BB->getParent()->front();
   }

   if (ReturnInst *RI = dyn_cast<ReturnInst>(NewBB->getTerminator()))
     Returns.push_back(RI);
 }

 /// ConstantFoldMappedInstruction - Constant fold the specified instruction,
 /// mapping its operands through VMap if they are available.
 Constant *PruningFunctionCloner::
 ConstantFoldMappedInstruction(const Instruction *I) {
   SmallVector<Constant*, 8> Ops;
   for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
     if (Constant *Op = dyn_cast_or_null<Constant>(MapValue(I->getOperand(i),
                                                            VMap,
                   ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges)))
       Ops.push_back(Op);
     else
       return 0;  // All operands not constant!

   if (const CmpInst *CI = dyn_cast<CmpInst>(I))
     return ConstantFoldCompareInstOperands(CI->getPredicate(), Ops[0], Ops[1],
                                            TD);

   if (const LoadInst *LI = dyn_cast<LoadInst>(I))
     if (!LI->isVolatile())
       return ConstantFoldLoadFromConstPtr(Ops[0], TD);

   return ConstantFoldInstOperands(I->getOpcode(), I->getType(), Ops, TD);
 }

 /// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto,
 /// except that it does some simple constant prop and DCE on the fly.  The
 /// effect of this is to copy significantly less code in cases where (for
 /// example) a function call with constant arguments is inlined, and those
 /// constant arguments cause a significant amount of code in the callee to be
 /// dead.  Since this doesn't produce an exact copy of the input, it can't be
 /// used for things like CloneFunction or CloneModule.
 void llvm::CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
                                      ValueToValueMapTy &VMap,
                                      bool ModuleLevelChanges,
                                      SmallVectorImpl<ReturnInst*> &Returns,
                                      const char *NameSuffix,
                                      ClonedCodeInfo *CodeInfo,
                                      const TargetData *TD,
                                      Instruction *TheCall) {
   assert(NameSuffix && "NameSuffix cannot be null!");

 #ifndef NDEBUG
   for (Function::const_arg_iterator II = OldFunc->arg_begin(),
        E = OldFunc->arg_end(); II != E; ++II)
     assert(VMap.count(II) && "No mapping from source argument specified!");
 #endif

   PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges,
                             Returns, NameSuffix, CodeInfo, TD);

   // Clone the entry block, and anything recursively reachable from it.
   std::vector<const BasicBlock*> CloneWorklist;
   CloneWorklist.push_back(&OldFunc->getEntryBlock());
   while (!CloneWorklist.empty()) {
     const BasicBlock *BB = CloneWorklist.back();
     CloneWorklist.pop_back();
     PFC.CloneBlock(BB, CloneWorklist);
   }

   // Loop over all of the basic blocks in the old function.  If the block was
   // reachable, we have cloned it and the old block is now in the value map:
   // insert it into the new function in the right order.  If not, ignore it.
   //
   // Defer PHI resolution until rest of function is resolved.
   SmallVector<const PHINode*, 16> PHIToResolve;
   for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
        BI != BE; ++BI) {
     Value *V = VMap[BI];
     BasicBlock *NewBB = cast_or_null<BasicBlock>(V);
     if (NewBB == 0) continue;  // Dead block.

     // Add the new block to the new function.
     NewFunc->getBasicBlockList().push_back(NewBB);

     // Loop over all of the instructions in the block, fixing up operand
     // references as we go.  This uses VMap to do all the hard work.
     //
     BasicBlock::iterator I = NewBB->begin();

     DebugLoc TheCallDL;
     if (TheCall)
       TheCallDL = TheCall->getDebugLoc();

     // Handle PHI nodes specially, as we have to remove references to dead
     // blocks.
     if (PHINode *PN = dyn_cast<PHINode>(I)) {
       // Skip over all PHI nodes, remembering them for later.
       BasicBlock::const_iterator OldI = BI->begin();
       for (; (PN = dyn_cast<PHINode>(I)); ++I, ++OldI)
         PHIToResolve.push_back(cast<PHINode>(OldI));
     }

     // Otherwise, remap the rest of the instructions normally.
     for (; I != NewBB->end(); ++I)
       RemapInstruction(I, VMap,
                        ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
   }

   // Defer PHI resolution until rest of function is resolved, PHI resolution
   // requires the CFG to be up-to-date.
   for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
     const PHINode *OPN = PHIToResolve[phino];
     unsigned NumPreds = OPN->getNumIncomingValues();
     const BasicBlock *OldBB = OPN->getParent();
     BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]);

     // Map operands for blocks that are live and remove operands for blocks
     // that are dead.
     for (; phino != PHIToResolve.size() &&
          PHIToResolve[phino]->getParent() == OldBB; ++phino) {
       OPN = PHIToResolve[phino];
       PHINode *PN = cast<PHINode>(VMap[OPN]);
       for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
         Value *V = VMap[PN->getIncomingBlock(pred)];
         if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) {
           Value *InVal = MapValue(PN->getIncomingValue(pred),
                                   VMap,
                         ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
           assert(InVal && "Unknown input value?");
           PN->setIncomingValue(pred, InVal);
           PN->setIncomingBlock(pred, MappedBlock);
         } else {
           PN->removeIncomingValue(pred, false);
           --pred, --e;  // Revisit the next entry.
         }
       }
     }

     // The loop above has removed PHI entries for those blocks that are dead
     // and has updated others.  However, if a block is live (i.e. copied over)
     // but its terminator has been changed to not go to this block, then our
     // phi nodes will have invalid entries.  Update the PHI nodes in this
     // case.
     PHINode *PN = cast<PHINode>(NewBB->begin());
     NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
     if (NumPreds != PN->getNumIncomingValues()) {
       assert(NumPreds < PN->getNumIncomingValues());
       // Count how many times each predecessor comes to this block.
       std::map<BasicBlock*, unsigned> PredCount;
       for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
            PI != E; ++PI)
         --PredCount[*PI];

       // Figure out how many entries to remove from each PHI.
       for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
         ++PredCount[PN->getIncomingBlock(i)];

       // At this point, the excess predecessor entries are positive in the
       // map.  Loop over all of the PHIs and remove excess predecessor
       // entries.
       BasicBlock::iterator I = NewBB->begin();
       for (; (PN = dyn_cast<PHINode>(I)); ++I) {
         for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(),
              E = PredCount.end(); PCI != E; ++PCI) {
           BasicBlock *Pred     = PCI->first;
           for (unsigned NumToRemove = PCI->second; NumToRemove; --NumToRemove)
             PN->removeIncomingValue(Pred, false);
         }
       }
     }

     // If the loops above have made these phi nodes have 0 or 1 operand,
     // replace them with undef or the input value.  We must do this for
     // correctness, because 0-operand phis are not valid.
     PN = cast<PHINode>(NewBB->begin());
     if (PN->getNumIncomingValues() == 0) {
       BasicBlock::iterator I = NewBB->begin();
       BasicBlock::const_iterator OldI = OldBB->begin();
       while ((PN = dyn_cast<PHINode>(I++))) {
         Value *NV = UndefValue::get(PN->getType());
         PN->replaceAllUsesWith(NV);
         assert(VMap[OldI] == PN && "VMap mismatch");
         VMap[OldI] = NV;
         PN->eraseFromParent();
         ++OldI;
       }
     }
     // NOTE: We cannot eliminate single entry phi nodes here, because of
     // VMap.  Single entry phi nodes can have multiple VMap entries
     // pointing at them.  Thus, deleting one would require scanning the VMap
     // to update any entries in it that would require that.  This would be
     // really slow.
   }

   // Now that the inlined function body has been fully constructed, go through
   // and zap unconditional fall-through branches.  This happen all the time when
   // specializing code: code specialization turns conditional branches into
   // uncond branches, and this code folds them.
   Function::iterator I = cast<BasicBlock>(VMap[&OldFunc->getEntryBlock()]);
   while (I != NewFunc->end()) {
     BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator());
     if (!BI || BI->isConditional()) { ++I; continue; }

     // Note that we can't eliminate uncond branches if the destination has
     // single-entry PHI nodes.  Eliminating the single-entry phi nodes would
     // require scanning the VMap to update any entries that point to the phi
     // node.
     BasicBlock *Dest = BI->getSuccessor(0);
     if (!Dest->getSinglePredecessor() || isa<PHINode>(Dest->begin())) {
       ++I; continue;
     }

     // We know all single-entry PHI nodes in the inlined function have been
     // removed, so we just need to splice the blocks.
     BI->eraseFromParent();

     // Make all PHI nodes that referred to Dest now refer to I as their source.
     Dest->replaceAllUsesWith(I);

     // Move all the instructions in the succ to the pred.
     I->getInstList().splice(I->end(), Dest->getInstList());

     // Remove the dest block.
     Dest->eraseFromParent();

     // Do not increment I, iteratively merge all things this block branches to.
   }
 }
	//===- CloneFunction.cpp - Clone a function into another function ---------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//
	//
	// This file implements the CloneFunctionInto interface, which is used as the
	// low-level function cloner. This is used by the CloneFunction and function
	// inliner to do the dirty work of copying the body of a function around.
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/Transforms/Utils/Cloning.h"
	#include "llvm/Constants.h"
	#include "llvm/DerivedTypes.h"
	#include "llvm/Instructions.h"
	#include "llvm/IntrinsicInst.h"
	#include "llvm/GlobalVariable.h"
	#include "llvm/Function.h"
	#include "llvm/LLVMContext.h"
	#include "llvm/Metadata.h"
	#include "llvm/Support/CFG.h"
	#include "llvm/Transforms/Utils/ValueMapper.h"
	#include "llvm/Analysis/ConstantFolding.h"
	#include "llvm/Analysis/DebugInfo.h"
	#include "llvm/ADT/SmallVector.h"
	#include <map>
	using namespace llvm;

	// CloneBasicBlock - See comments in Cloning.h
	BasicBlock llvm::CloneBasicBlock(const BasicBlock BB,
	ValueToValueMapTy &VMap,
	const Twine &NameSuffix, Function *F,
	ClonedCodeInfo *CodeInfo) {
	BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "", F);
	if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);

	bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;

	// Loop over all instructions, and copy them over.
	for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end();
	II != IE; ++II) {
	Instruction *NewInst = II->clone();
	if (II->hasName())
	NewInst->setName(II->getName()+NameSuffix);
	NewBB->getInstList().push_back(NewInst);
	VMap[II] = NewInst; // Add instruction map to value.

	hasCalls \|= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
	if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
	if (isa<ConstantInt>(AI->getArraySize()))
	hasStaticAllocas = true;
	else
	hasDynamicAllocas = true;
	}
	}

	if (CodeInfo) {
	CodeInfo->ContainsCalls \|= hasCalls;
	CodeInfo->ContainsUnwinds \|= isa<UnwindInst>(BB->getTerminator());
	CodeInfo->ContainsDynamicAllocas \|= hasDynamicAllocas;
	CodeInfo->ContainsDynamicAllocas \|= hasStaticAllocas &&
	BB != &BB->getParent()->getEntryBlock();
	}
	return NewBB;
	}

	// Clone OldFunc into NewFunc, transforming the old arguments into references to
	// VMap values.
	//
	void llvm::CloneFunctionInto(Function NewFunc, const Function OldFunc,
	ValueToValueMapTy &VMap,
	bool ModuleLevelChanges,
	SmallVectorImpl<ReturnInst*> &Returns,
	const char NameSuffix, ClonedCodeInfo CodeInfo) {
	assert(NameSuffix && "NameSuffix cannot be null!");

	#ifndef NDEBUG
	for (Function::const_arg_iterator I = OldFunc->arg_begin(),
	E = OldFunc->arg_end(); I != E; ++I)
	assert(VMap.count(I) && "No mapping from source argument specified!");
	#endif

	// Clone any attributes.
	if (NewFunc->arg_size() == OldFunc->arg_size())
	NewFunc->copyAttributesFrom(OldFunc);
	else {
	//Some arguments were deleted with the VMap. Copy arguments one by one
	for (Function::const_arg_iterator I = OldFunc->arg_begin(),
	E = OldFunc->arg_end(); I != E; ++I)
	if (Argument* Anew = dyn_cast<Argument>(VMap[I]))
	Anew->addAttr( OldFunc->getAttributes()
	.getParamAttributes(I->getArgNo() + 1));
	NewFunc->setAttributes(NewFunc->getAttributes()
	.addAttr(0, OldFunc->getAttributes()
	.getRetAttributes()));
	NewFunc->setAttributes(NewFunc->getAttributes()
	.addAttr(~0, OldFunc->getAttributes()
	.getFnAttributes()));

	}

	// Loop over all of the basic blocks in the function, cloning them as
	// appropriate. Note that we save BE this way in order to handle cloning of
	// recursive functions into themselves.
	//
	for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
	BI != BE; ++BI) {
	const BasicBlock &BB = *BI;

	// Create a new basic block and copy instructions into it!
	BasicBlock *CBB = CloneBasicBlock(&BB, VMap, NameSuffix, NewFunc, CodeInfo);
	VMap[&BB] = CBB; // Add basic block mapping.

	if (ReturnInst *RI = dyn_cast<ReturnInst>(CBB->getTerminator()))
	Returns.push_back(RI);
	}

	// Loop over all of the instructions in the function, fixing up operand
	// references as we go. This uses VMap to do all the hard work.
	for (Function::iterator BB = cast<BasicBlock>(VMap[OldFunc->begin()]),
	BE = NewFunc->end(); BB != BE; ++BB)
	// Loop over all instructions, fixing each one as we find it...
	for (BasicBlock::iterator II = BB->begin(); II != BB->end(); ++II)
	RemapInstruction(II, VMap,
	ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
	}

	/// CloneFunction - Return a copy of the specified function, but without
	/// embedding the function into another module. Also, any references specified
	/// in the VMap are changed to refer to their mapped value instead of the
	/// original one. If any of the arguments to the function are in the VMap,
	/// the arguments are deleted from the resultant function. The VMap is
	/// updated to include mappings from all of the instructions and basicblocks in
	/// the function from their old to new values.
	///
	Function llvm::CloneFunction(const Function F, ValueToValueMapTy &VMap,
	bool ModuleLevelChanges,
	ClonedCodeInfo *CodeInfo) {
	std::vector<Type*> ArgTypes;

	// The user might be deleting arguments to the function by specifying them in
	// the VMap. If so, we need to not add the arguments to the arg ty vector
	//
	for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
	I != E; ++I)
	if (VMap.count(I) == 0) // Haven't mapped the argument to anything yet?
	ArgTypes.push_back(I->getType());

	// Create a new function type...
	FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(),
	ArgTypes, F->getFunctionType()->isVarArg());

	// Create the new function...
	Function *NewF = Function::Create(FTy, F->getLinkage(), F->getName());

	// Loop over the arguments, copying the names of the mapped arguments over...
	Function::arg_iterator DestI = NewF->arg_begin();
	for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
	I != E; ++I)
	if (VMap.count(I) == 0) { // Is this argument preserved?
	DestI->setName(I->getName()); // Copy the name over...
	VMap[I] = DestI++; // Add mapping to VMap
	}

	SmallVector<ReturnInst*, 8> Returns; // Ignore returns cloned.
	CloneFunctionInto(NewF, F, VMap, ModuleLevelChanges, Returns, "", CodeInfo);
	return NewF;
	}



	namespace {
	/// PruningFunctionCloner - This class is a private class used to implement
	/// the CloneAndPruneFunctionInto method.
	struct PruningFunctionCloner {
	Function *NewFunc;
	const Function *OldFunc;
	ValueToValueMapTy &VMap;
	bool ModuleLevelChanges;
	SmallVectorImpl<ReturnInst*> &Returns;
	const char *NameSuffix;
	ClonedCodeInfo *CodeInfo;
	const TargetData *TD;
	public:
	PruningFunctionCloner(Function newFunc, const Function oldFunc,
	ValueToValueMapTy &valueMap,
	bool moduleLevelChanges,
	SmallVectorImpl<ReturnInst*> &returns,
	const char *nameSuffix,
	ClonedCodeInfo *codeInfo,
	const TargetData *td)
	: NewFunc(newFunc), OldFunc(oldFunc),
	VMap(valueMap), ModuleLevelChanges(moduleLevelChanges),
	Returns(returns), NameSuffix(nameSuffix), CodeInfo(codeInfo), TD(td) {
	}

	/// CloneBlock - The specified block is found to be reachable, clone it and
	/// anything that it can reach.
	void CloneBlock(const BasicBlock *BB,
	std::vector<const BasicBlock*> &ToClone);

	public:
	/// ConstantFoldMappedInstruction - Constant fold the specified instruction,
	/// mapping its operands through VMap if they are available.
	Constant ConstantFoldMappedInstruction(const Instruction I);
	};
	}

	/// CloneBlock - The specified block is found to be reachable, clone it and
	/// anything that it can reach.
	void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
	std::vector<const BasicBlock*> &ToClone){
	TrackingVH<Value> &BBEntry = VMap[BB];

	// Have we already cloned this block?
	if (BBEntry) return;

	// Nope, clone it now.
	BasicBlock *NewBB;
	BBEntry = NewBB = BasicBlock::Create(BB->getContext());
	if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);

	bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;

	// Loop over all instructions, and copy them over, DCE'ing as we go. This
	// loop doesn't include the terminator.
	for (BasicBlock::const_iterator II = BB->begin(), IE = --BB->end();
	II != IE; ++II) {
	// If this instruction constant folds, don't bother cloning the instruction,
	// instead, just add the constant to the value map.
	if (Constant *C = ConstantFoldMappedInstruction(II)) {
	VMap[II] = C;
	continue;
	}

	Instruction *NewInst = II->clone();
	if (II->hasName())
	NewInst->setName(II->getName()+NameSuffix);
	NewBB->getInstList().push_back(NewInst);
	VMap[II] = NewInst; // Add instruction map to value.

	hasCalls \|= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
	if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
	if (isa<ConstantInt>(AI->getArraySize()))
	hasStaticAllocas = true;
	else
	hasDynamicAllocas = true;
	}
	}

	// Finally, clone over the terminator.
	const TerminatorInst *OldTI = BB->getTerminator();
	bool TerminatorDone = false;
	if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
	if (BI->isConditional()) {
	// If the condition was a known constant in the callee...
	ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
	// Or is a known constant in the caller...
	if (Cond == 0) {
	Value *V = VMap[BI->getCondition()];
	Cond = dyn_cast_or_null<ConstantInt>(V);
	}

	// Constant fold to uncond branch!
	if (Cond) {
	BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue());
	VMap[OldTI] = BranchInst::Create(Dest, NewBB);
	ToClone.push_back(Dest);
	TerminatorDone = true;
	}
	}
	} else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
	// If switching on a value known constant in the caller.
	ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
	if (Cond == 0) { // Or known constant after constant prop in the callee...
	Value *V = VMap[SI->getCondition()];
	Cond = dyn_cast_or_null<ConstantInt>(V);
	}
	if (Cond) { // Constant fold to uncond branch!
	BasicBlock *Dest = SI->getSuccessor(SI->findCaseValue(Cond));
	VMap[OldTI] = BranchInst::Create(Dest, NewBB);
	ToClone.push_back(Dest);
	TerminatorDone = true;
	}
	}

	if (!TerminatorDone) {
	Instruction *NewInst = OldTI->clone();
	if (OldTI->hasName())
	NewInst->setName(OldTI->getName()+NameSuffix);
	NewBB->getInstList().push_back(NewInst);
	VMap[OldTI] = NewInst; // Add instruction map to value.

	// Recursively clone any reachable successor blocks.
	const TerminatorInst *TI = BB->getTerminator();
	for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
	ToClone.push_back(TI->getSuccessor(i));
	}

	if (CodeInfo) {
	CodeInfo->ContainsCalls \|= hasCalls;
	CodeInfo->ContainsUnwinds \|= isa<UnwindInst>(OldTI);
	CodeInfo->ContainsDynamicAllocas \|= hasDynamicAllocas;
	CodeInfo->ContainsDynamicAllocas \|= hasStaticAllocas &&
	BB != &BB->getParent()->front();
	}

	if (ReturnInst *RI = dyn_cast<ReturnInst>(NewBB->getTerminator()))
	Returns.push_back(RI);
	}

	/// ConstantFoldMappedInstruction - Constant fold the specified instruction,
	/// mapping its operands through VMap if they are available.
	Constant *PruningFunctionCloner::
	ConstantFoldMappedInstruction(const Instruction *I) {
	SmallVector<Constant*, 8> Ops;
	for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
	if (Constant *Op = dyn_cast_or_null<Constant>(MapValue(I->getOperand(i),
	VMap,
	ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges)))
	Ops.push_back(Op);
	else
	return 0; // All operands not constant!

	if (const CmpInst *CI = dyn_cast<CmpInst>(I))
	return ConstantFoldCompareInstOperands(CI->getPredicate(), Ops[0], Ops[1],
	TD);

	if (const LoadInst *LI = dyn_cast<LoadInst>(I))
	if (!LI->isVolatile())
	return ConstantFoldLoadFromConstPtr(Ops[0], TD);

	return ConstantFoldInstOperands(I->getOpcode(), I->getType(), Ops, TD);
	}

	/// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto,
	/// except that it does some simple constant prop and DCE on the fly. The
	/// effect of this is to copy significantly less code in cases where (for
	/// example) a function call with constant arguments is inlined, and those
	/// constant arguments cause a significant amount of code in the callee to be
	/// dead. Since this doesn't produce an exact copy of the input, it can't be
	/// used for things like CloneFunction or CloneModule.
	void llvm::CloneAndPruneFunctionInto(Function NewFunc, const Function OldFunc,
	ValueToValueMapTy &VMap,
	bool ModuleLevelChanges,
	SmallVectorImpl<ReturnInst*> &Returns,
	const char *NameSuffix,
	ClonedCodeInfo *CodeInfo,
	const TargetData *TD,
	Instruction *TheCall) {
	assert(NameSuffix && "NameSuffix cannot be null!");

	#ifndef NDEBUG
	for (Function::const_arg_iterator II = OldFunc->arg_begin(),
	E = OldFunc->arg_end(); II != E; ++II)
	assert(VMap.count(II) && "No mapping from source argument specified!");
	#endif

	PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges,
	Returns, NameSuffix, CodeInfo, TD);

	// Clone the entry block, and anything recursively reachable from it.
	std::vector<const BasicBlock*> CloneWorklist;
	CloneWorklist.push_back(&OldFunc->getEntryBlock());
	while (!CloneWorklist.empty()) {
	const BasicBlock *BB = CloneWorklist.back();
	CloneWorklist.pop_back();
	PFC.CloneBlock(BB, CloneWorklist);
	}

	// Loop over all of the basic blocks in the old function. If the block was
	// reachable, we have cloned it and the old block is now in the value map:
	// insert it into the new function in the right order. If not, ignore it.
	//
	// Defer PHI resolution until rest of function is resolved.
	SmallVector<const PHINode*, 16> PHIToResolve;
	for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
	BI != BE; ++BI) {
	Value *V = VMap[BI];
	BasicBlock *NewBB = cast_or_null<BasicBlock>(V);
	if (NewBB == 0) continue; // Dead block.

	// Add the new block to the new function.
	NewFunc->getBasicBlockList().push_back(NewBB);

	// Loop over all of the instructions in the block, fixing up operand
	// references as we go. This uses VMap to do all the hard work.
	//
	BasicBlock::iterator I = NewBB->begin();

	DebugLoc TheCallDL;
	if (TheCall)
	TheCallDL = TheCall->getDebugLoc();

	// Handle PHI nodes specially, as we have to remove references to dead
	// blocks.
	if (PHINode *PN = dyn_cast<PHINode>(I)) {
	// Skip over all PHI nodes, remembering them for later.
	BasicBlock::const_iterator OldI = BI->begin();
	for (; (PN = dyn_cast<PHINode>(I)); ++I, ++OldI)
	PHIToResolve.push_back(cast<PHINode>(OldI));
	}

	// Otherwise, remap the rest of the instructions normally.
	for (; I != NewBB->end(); ++I)
	RemapInstruction(I, VMap,
	ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
	}

	// Defer PHI resolution until rest of function is resolved, PHI resolution
	// requires the CFG to be up-to-date.
	for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
	const PHINode *OPN = PHIToResolve[phino];
	unsigned NumPreds = OPN->getNumIncomingValues();
	const BasicBlock *OldBB = OPN->getParent();
	BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]);

	// Map operands for blocks that are live and remove operands for blocks
	// that are dead.
	for (; phino != PHIToResolve.size() &&
	PHIToResolve[phino]->getParent() == OldBB; ++phino) {
	OPN = PHIToResolve[phino];
	PHINode *PN = cast<PHINode>(VMap[OPN]);
	for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
	Value *V = VMap[PN->getIncomingBlock(pred)];
	if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) {
	Value *InVal = MapValue(PN->getIncomingValue(pred),
	VMap,
	ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
	assert(InVal && "Unknown input value?");
	PN->setIncomingValue(pred, InVal);
	PN->setIncomingBlock(pred, MappedBlock);
	} else {
	PN->removeIncomingValue(pred, false);
	--pred, --e; // Revisit the next entry.
	}
	}
	}

	// The loop above has removed PHI entries for those blocks that are dead
	// and has updated others. However, if a block is live (i.e. copied over)
	// but its terminator has been changed to not go to this block, then our
	// phi nodes will have invalid entries. Update the PHI nodes in this
	// case.
	PHINode *PN = cast<PHINode>(NewBB->begin());
	NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
	if (NumPreds != PN->getNumIncomingValues()) {
	assert(NumPreds < PN->getNumIncomingValues());
	// Count how many times each predecessor comes to this block.
	std::map<BasicBlock*, unsigned> PredCount;
	for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
	PI != E; ++PI)
	--PredCount[*PI];

	// Figure out how many entries to remove from each PHI.
	for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
	++PredCount[PN->getIncomingBlock(i)];

	// At this point, the excess predecessor entries are positive in the
	// map. Loop over all of the PHIs and remove excess predecessor
	// entries.
	BasicBlock::iterator I = NewBB->begin();
	for (; (PN = dyn_cast<PHINode>(I)); ++I) {
	for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(),
	E = PredCount.end(); PCI != E; ++PCI) {
	BasicBlock *Pred = PCI->first;
	for (unsigned NumToRemove = PCI->second; NumToRemove; --NumToRemove)
	PN->removeIncomingValue(Pred, false);
	}
	}
	}

	// If the loops above have made these phi nodes have 0 or 1 operand,
	// replace them with undef or the input value. We must do this for
	// correctness, because 0-operand phis are not valid.
	PN = cast<PHINode>(NewBB->begin());
	if (PN->getNumIncomingValues() == 0) {
	BasicBlock::iterator I = NewBB->begin();
	BasicBlock::const_iterator OldI = OldBB->begin();
	while ((PN = dyn_cast<PHINode>(I++))) {
	Value *NV = UndefValue::get(PN->getType());
	PN->replaceAllUsesWith(NV);
	assert(VMap[OldI] == PN && "VMap mismatch");
	VMap[OldI] = NV;
	PN->eraseFromParent();
	++OldI;
	}
	}
	// NOTE: We cannot eliminate single entry phi nodes here, because of
	// VMap. Single entry phi nodes can have multiple VMap entries
	// pointing at them. Thus, deleting one would require scanning the VMap
	// to update any entries in it that would require that. This would be
	// really slow.
	}

	// Now that the inlined function body has been fully constructed, go through
	// and zap unconditional fall-through branches. This happen all the time when
	// specializing code: code specialization turns conditional branches into
	// uncond branches, and this code folds them.
	Function::iterator I = cast<BasicBlock>(VMap[&OldFunc->getEntryBlock()]);
	while (I != NewFunc->end()) {
	BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator());
	if (!BI \|\| BI->isConditional()) { ++I; continue; }

	// Note that we can't eliminate uncond branches if the destination has
	// single-entry PHI nodes. Eliminating the single-entry phi nodes would
	// require scanning the VMap to update any entries that point to the phi
	// node.
	BasicBlock *Dest = BI->getSuccessor(0);
	if (!Dest->getSinglePredecessor() \|\| isa<PHINode>(Dest->begin())) {
	++I; continue;
	}

	// We know all single-entry PHI nodes in the inlined function have been
	// removed, so we just need to splice the blocks.
	BI->eraseFromParent();

	// Make all PHI nodes that referred to Dest now refer to I as their source.
	Dest->replaceAllUsesWith(I);

	// Move all the instructions in the succ to the pred.
	I->getInstList().splice(I->end(), Dest->getInstList());

	// Remove the dest block.
	Dest->eraseFromParent();

	// Do not increment I, iteratively merge all things this block branches to.
	}
	}