//
// The LLVM Compiler Infrastructure
//
-// This file was developed by the LLVM research group and is distributed under
-// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
#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 "ValueMapper.h"
-#include "llvm/Transforms/Utils/Local.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,
- std::map<const Value*, Value*> &ValueMap,
- const char *NameSuffix, Function *F,
+ ValueToValueMapTy &VMap,
+ const Twine &NameSuffix, Function *F,
ClonedCodeInfo *CodeInfo) {
- BasicBlock *NewBB = new BasicBlock("", F);
+ BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "", F);
if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
if (II->hasName())
NewInst->setName(II->getName()+NameSuffix);
NewBB->getInstList().push_back(NewInst);
- ValueMap[II] = NewInst; // Add instruction map to value.
+ VMap[II] = NewInst; // Add instruction map to value.
- hasCalls |= isa<CallInst>(II);
+ hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
if (isa<ConstantInt>(AI->getArraySize()))
hasStaticAllocas = true;
CodeInfo->ContainsUnwinds |= isa<UnwindInst>(BB->getTerminator());
CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
- BB != &BB->getParent()->front();
+ BB != &BB->getParent()->getEntryBlock();
}
return NewBB;
}
// Clone OldFunc into NewFunc, transforming the old arguments into references to
-// ArgMap values.
+// VMap values.
//
void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
- std::map<const Value*, Value*> &ValueMap,
- std::vector<ReturnInst*> &Returns,
+ 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(ValueMap.count(I) && "No mapping from source argument specified!");
+ 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.
const BasicBlock &BB = *BI;
// Create a new basic block and copy instructions into it!
- BasicBlock *CBB = CloneBasicBlock(&BB, ValueMap, NameSuffix, NewFunc,
- CodeInfo);
- ValueMap[&BB] = CBB; // Add basic block mapping.
+ 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 ValueMap to do all the hard work.
- //
- for (Function::iterator BB = cast<BasicBlock>(ValueMap[OldFunc->begin()]),
+ // 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, ValueMap);
+ 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 ValueMap are changed to refer to their mapped value instead of the
-/// original one. If any of the arguments to the function are in the ValueMap,
-/// the arguments are deleted from the resultant function. The ValueMap is
+/// 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,
- std::map<const Value*, Value*> &ValueMap,
+Function *llvm::CloneFunction(const Function *F, ValueToValueMapTy &VMap,
+ bool ModuleLevelChanges,
ClonedCodeInfo *CodeInfo) {
- std::vector<const Type*> ArgTypes;
+ std::vector<Type*> ArgTypes;
// The user might be deleting arguments to the function by specifying them in
- // the ValueMap. If so, we need to not add the arguments to the arg ty vector
+ // 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 (ValueMap.count(I) == 0) // Haven't mapped the argument to anything yet?
+ if (VMap.count(I) == 0) // Haven't mapped the argument to anything yet?
ArgTypes.push_back(I->getType());
// Create a new function type...
ArgTypes, F->getFunctionType()->isVarArg());
// Create the new function...
- Function *NewF = new Function(FTy, F->getLinkage(), F->getName());
+ 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 (ValueMap.count(I) == 0) { // Is this argument preserved?
+ if (VMap.count(I) == 0) { // Is this argument preserved?
DestI->setName(I->getName()); // Copy the name over...
- ValueMap[I] = DestI++; // Add mapping to ValueMap
+ VMap[I] = DestI++; // Add mapping to VMap
}
- std::vector<ReturnInst*> Returns; // Ignore returns cloned...
- CloneFunctionInto(NewF, F, ValueMap, Returns, "", CodeInfo);
+ SmallVector<ReturnInst*, 8> Returns; // Ignore returns cloned.
+ CloneFunctionInto(NewF, F, VMap, ModuleLevelChanges, Returns, "", CodeInfo);
return NewF;
}
struct PruningFunctionCloner {
Function *NewFunc;
const Function *OldFunc;
- std::map<const Value*, Value*> &ValueMap;
- std::vector<ReturnInst*> &Returns;
+ ValueToValueMapTy &VMap;
+ bool ModuleLevelChanges;
+ SmallVectorImpl<ReturnInst*> &Returns;
const char *NameSuffix;
ClonedCodeInfo *CodeInfo;
-
+ const TargetData *TD;
public:
PruningFunctionCloner(Function *newFunc, const Function *oldFunc,
- std::map<const Value*, Value*> &valueMap,
- std::vector<ReturnInst*> &returns,
+ ValueToValueMapTy &valueMap,
+ bool moduleLevelChanges,
+ SmallVectorImpl<ReturnInst*> &returns,
const char *nameSuffix,
- ClonedCodeInfo *codeInfo)
- : NewFunc(newFunc), OldFunc(oldFunc), ValueMap(valueMap), Returns(returns),
- NameSuffix(nameSuffix), CodeInfo(codeInfo) {
+ 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);
+ void CloneBlock(const BasicBlock *BB,
+ std::vector<const BasicBlock*> &ToClone);
public:
/// ConstantFoldMappedInstruction - Constant fold the specified instruction,
- /// mapping its operands through ValueMap if they are available.
+ /// 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) {
- Value *&BBEntry = ValueMap[BB];
+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 = new BasicBlock();
+ 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();
+ 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)) {
- ValueMap[II] = C;
+ VMap[II] = C;
continue;
}
-
+
Instruction *NewInst = II->clone();
if (II->hasName())
NewInst->setName(II->getName()+NameSuffix);
NewBB->getInstList().push_back(NewInst);
- ValueMap[II] = NewInst; // Add instruction map to value.
+ VMap[II] = NewInst; // Add instruction map to value.
- hasCalls |= isa<CallInst>(II);
+ hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
if (isa<ConstantInt>(AI->getArraySize()))
hasStaticAllocas = 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>(BB->getTerminator());
+ 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);
-
- // Recursively clone any reachable successor blocks.
- const TerminatorInst *TI = BB->getTerminator();
- for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
- CloneBlock(TI->getSuccessor(i));
}
/// ConstantFoldMappedInstruction - Constant fold the specified instruction,
-/// mapping its operands through ValueMap if they are available.
+/// mapping its operands through VMap if they are available.
Constant *PruningFunctionCloner::
ConstantFoldMappedInstruction(const Instruction *I) {
- if (isa<BinaryOperator>(I) || isa<ShiftInst>(I)) {
- if (Constant *Op0 = dyn_cast_or_null<Constant>(MapValue(I->getOperand(0),
- ValueMap)))
- if (Constant *Op1 = dyn_cast_or_null<Constant>(MapValue(I->getOperand(1),
- ValueMap)))
- return ConstantExpr::get(I->getOpcode(), Op0, Op1);
- return 0;
- }
-
- std::vector<Constant*> Ops;
+ 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),
- ValueMap)))
+ VMap,
+ ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges)))
Ops.push_back(Op);
else
return 0; // All operands not constant!
- return ConstantFoldInstOperands(I->getOpcode(), I->getType(), Ops);
-}
+ 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 (ConstantExpr *CE = dyn_cast<ConstantExpr>(Ops[0]))
+ if (!LI->isVolatile() && CE->getOpcode() == Instruction::GetElementPtr)
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(CE->getOperand(0)))
+ if (GV->isConstant() && GV->hasDefinitiveInitializer())
+ return ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(),
+ CE);
+
+ return ConstantFoldInstOperands(I->getOpcode(), I->getType(), &Ops[0],
+ Ops.size(), 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 exactly copy of the input, it can't 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,
- std::map<const Value*, Value*> &ValueMap,
- std::vector<ReturnInst*> &Returns,
+ ValueToValueMapTy &VMap,
+ bool ModuleLevelChanges,
+ SmallVectorImpl<ReturnInst*> &Returns,
const char *NameSuffix,
- ClonedCodeInfo *CodeInfo) {
+ ClonedCodeInfo *CodeInfo,
+ const TargetData *TD,
+ Instruction *TheCall) {
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(ValueMap.count(I) && "No mapping from source argument specified!");
+ 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, ValueMap, Returns,
- NameSuffix, CodeInfo);
+
+ PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges,
+ Returns, NameSuffix, CodeInfo, TD);
// Clone the entry block, and anything recursively reachable from it.
- PFC.CloneBlock(&OldFunc->getEntryBlock());
+ 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) {
- BasicBlock *NewBB = cast_or_null<BasicBlock>(ValueMap[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 ValueMap to do all the hard work.
+ // 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)) {
- unsigned NumPreds = PN->getNumIncomingValues();
- for (; (PN = dyn_cast<PHINode>(I)); ++I) {
- for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
- if (BasicBlock *MappedBlock =
- cast<BasicBlock>(ValueMap[PN->getIncomingBlock(pred)])) {
- Value *InVal = MapValue(PN->getIncomingValue(pred), ValueMap);
- assert(InVal && "Unknown input value?");
- PN->setIncomingValue(pred, InVal);
- PN->setIncomingBlock(pred, MappedBlock);
- } else {
- PN->removeIncomingValue(pred, false);
- --pred, --e; // Revisit the next entry.
- }
- }
- }
+ // 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, ValueMap);
+ 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.
+ }
+}
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