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This is a bulk commit that implements the following primary improvements: 

* We can now fold cast instructions into select instructions that
    have at least one constant operand.
  * We now optimize expressions more aggressively based on bits that are
    known to be zero.  These optimizations occur a lot in code that uses
    bitfields even in simple ways.
  * We now turn more cast-cast sequences into AND instructions.  Before we
    would only do this if it if all types were unsigned.  Now only the
    middle type needs to be unsigned (guaranteeing a zero extend).
  * We transform sign extensions into zero extensions in several cases.

This corresponds to these test/Regression/Transforms/InstCombine testcases:
  2004-11-22-Missed-and-fold.ll
  and.ll: test28-29
  cast.ll: test21-24
  and-or-and.ll
  cast-cast-to-and.ll
  zeroext-and-reduce.ll

llvm-svn: 19220
This commit is contained in:
Chris Lattner 2005-01-01 16:22:27 +00:00
parent da15d4ba49
commit 86102b8ad5
1 changed files with 268 additions and 78 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

324
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -486,31 +486,60 @@ struct AddMaskingAnd {
}
};
static Value *FoldOperationIntoSelectOperand(Instruction &BI, Value *SO,
static Value *FoldOperationIntoSelectOperand(Instruction &I, Value *SO,
InstCombiner *IC) {
if (isa<CastInst>(I)) {
if (Constant *SOC = dyn_cast<Constant>(SO))
return ConstantExpr::getCast(SOC, I.getType());
return IC->InsertNewInstBefore(new CastInst(SO, I.getType(),
SO->getName() + ".cast"), I);
}
// Figure out if the constant is the left or the right argument.
bool ConstIsRHS = isa<Constant>(BI.getOperand(1));
Constant *ConstOperand = cast<Constant>(BI.getOperand(ConstIsRHS));
bool ConstIsRHS = isa<Constant>(I.getOperand(1));
Constant *ConstOperand = cast<Constant>(I.getOperand(ConstIsRHS));
if (Constant *SOC = dyn_cast<Constant>(SO)) {
if (ConstIsRHS)
return ConstantExpr::get(BI.getOpcode(), SOC, ConstOperand);
return ConstantExpr::get(BI.getOpcode(), ConstOperand, SOC);
return ConstantExpr::get(I.getOpcode(), SOC, ConstOperand);
return ConstantExpr::get(I.getOpcode(), ConstOperand, SOC);
}
Value *Op0 = SO, *Op1 = ConstOperand;
if (!ConstIsRHS)
std::swap(Op0, Op1);
Instruction *New;
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&BI))
New = BinaryOperator::create(BO->getOpcode(), Op0, Op1);
else if (ShiftInst *SI = dyn_cast<ShiftInst>(&BI))
New = new ShiftInst(SI->getOpcode(), Op0, Op1);
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
New = BinaryOperator::create(BO->getOpcode(), Op0, Op1,SO->getName()+".op");
else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
New = new ShiftInst(SI->getOpcode(), Op0, Op1, SO->getName()+".sh");
else {
assert(0 && "Unknown binary instruction type!");
abort();
}
return IC->InsertNewInstBefore(New, BI);
return IC->InsertNewInstBefore(New, I);
}
// FoldOpIntoSelect - Given an instruction with a select as one operand and a
// constant as the other operand, try to fold the binary operator into the
// select arguments. This also works for Cast instructions, which obviously do
// not have a second operand.
static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
InstCombiner *IC) {
// Don't modify shared select instructions
if (!SI->hasOneUse()) return 0;
Value *TV = SI->getOperand(1);
Value *FV = SI->getOperand(2);
if (isa<Constant>(TV) || isa<Constant>(FV)) {
Value *SelectTrueVal = FoldOperationIntoSelectOperand(Op, TV, IC);
Value *SelectFalseVal = FoldOperationIntoSelectOperand(Op, FV, IC);
return new SelectInst(SI->getCondition(), SelectTrueVal,
SelectFalseVal);
}
return 0;
}
@ -555,26 +584,6 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
return ReplaceInstUsesWith(I, NewPN);
}
// FoldBinOpIntoSelect - Given an instruction with a select as one operand and a
// constant as the other operand, try to fold the binary operator into the
// select arguments.
static Instruction *FoldBinOpIntoSelect(Instruction &BI, SelectInst *SI,
InstCombiner *IC) {
// Don't modify shared select instructions
if (!SI->hasOneUse()) return 0;
Value *TV = SI->getOperand(1);
Value *FV = SI->getOperand(2);
if (isa<Constant>(TV) || isa<Constant>(FV)) {
Value *SelectTrueVal = FoldOperationIntoSelectOperand(BI, TV, IC);
Value *SelectFalseVal = FoldOperationIntoSelectOperand(BI, FV, IC);
return new SelectInst(SI->getCondition(), SelectTrueVal,
SelectFalseVal);
}
return 0;
}
Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
bool Changed = SimplifyCommutative(I);
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
@ -667,10 +676,9 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
}
}
// Try to fold constant add into select arguments.
if (SelectInst *SI = dyn_cast<SelectInst>(LHS))
if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
return R;
}
@ -761,7 +769,7 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
// Try to fold constant sub into select arguments.
if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
return R;
if (isa<PHINode>(Op0))
@ -889,7 +897,7 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
// Try to fold constant mul into select arguments.
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
return R;
if (isa<PHINode>(Op0))
@ -990,7 +998,7 @@ Instruction *InstCombiner::visitDiv(BinaryOperator &I) {
if (!RHS->isNullValue()) {
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
return R;
if (isa<PHINode>(Op0))
if (Instruction *NV = FoldOpIntoPhi(I))
@ -1066,7 +1074,7 @@ Instruction *InstCombiner::visitRem(BinaryOperator &I) {
if (!RHS->isNullValue()) {
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
return R;
if (isa<PHINode>(Op0))
if (Instruction *NV = FoldOpIntoPhi(I))
@ -1251,6 +1259,70 @@ struct FoldSetCCLogical {
};
/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero. We use
/// this predicate to simplify operations downstream. V and Mask are known to
/// be the same type.
static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask) {
if (isa<UndefValue>(V) || Mask->isNullValue())
return true;
if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V))
return ConstantExpr::getAnd(CI, Mask)->isNullValue();
if (Instruction *I = dyn_cast<Instruction>(V)) {
switch (I->getOpcode()) {
case Instruction::And:
// (X & C1) & C2 == 0 iff C1 & C2 == 0.
if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(I->getOperand(1)))
if (ConstantExpr::getAnd(CI, Mask)->isNullValue())
return true;
break;
case Instruction::Cast: {
const Type *SrcTy = I->getOperand(0)->getType();
if (SrcTy->isIntegral()) {
// (cast <ty> X to int) & C2 == 0 iff <ty> could not have contained C2.
if (SrcTy->isUnsigned() && // Only handle zero ext.
ConstantExpr::getCast(Mask, SrcTy)->isNullValue())
return true;
// If this is a noop cast, recurse.
if (SrcTy != Type::BoolTy)
if ((SrcTy->isSigned() && SrcTy->getUnsignedVersion() ==I->getType()) ||
SrcTy->getSignedVersion() == I->getType()) {
Constant *NewMask =
ConstantExpr::getCast(Mask, I->getOperand(0)->getType());
return MaskedValueIsZero(I->getOperand(0),
cast<ConstantIntegral>(NewMask));
}
}
break;
}
case Instruction::Shl:
// (shl X, C1) & C2 == 0 iff (-1 << C1) & C2 == 0
if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1))) {
Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType());
C1 = ConstantExpr::getShl(C1, SA);
C1 = ConstantExpr::getAnd(C1, Mask);
if (C1->isNullValue())
return true;
}
break;
case Instruction::Shr:
// (ushr X, C1) & C2 == 0 iff (-1 >> C1) & C2 == 0
if (ConstantUInt *SA = dyn_cast<ConstantUInt>(I->getOperand(1)))
if (I->getType()->isUnsigned()) {
Constant *C1 = ConstantIntegral::getAllOnesValue(I->getType());
C1 = ConstantExpr::getShr(C1, SA);
C1 = ConstantExpr::getAnd(C1, Mask);
if (C1->isNullValue())
return true;
}
break;
}
}
return false;
}
// OptAndOp - This handles expressions of the form ((val OP C1) & C2). Where
// the Op parameter is 'OP', OpRHS is 'C1', and AndRHS is 'C2'. Op is
// guaranteed to be either a shift instruction or a binary operator.
@ -1265,10 +1337,7 @@ Instruction *InstCombiner::OptAndOp(Instruction *Op,
switch (Op->getOpcode()) {
case Instruction::Xor:
if (Together->isNullValue()) {
// (X ^ C1) & C2 --> (X & C2) iff (C1&C2) == 0
return BinaryOperator::createAnd(X, AndRHS);
} else if (Op->hasOneUse()) {
if (Op->hasOneUse()) {
// (X ^ C1) & C2 --> (X & C2) ^ (C1&C2)
std::string OpName = Op->getName(); Op->setName("");
Instruction *And = BinaryOperator::createAnd(X, AndRHS, OpName);
@ -1277,10 +1346,6 @@ Instruction *InstCombiner::OptAndOp(Instruction *Op,
}
break;
case Instruction::Or:
// (X | C1) & C2 --> X & C2 iff C1 & C1 == 0
if (Together->isNullValue())
return BinaryOperator::createAnd(X, AndRHS);
else {
if (Together == AndRHS) // (X | C) & C --> C
return ReplaceInstUsesWith(TheAnd, AndRHS);
@ -1291,7 +1356,6 @@ Instruction *InstCombiner::OptAndOp(Instruction *Op,
InsertNewInstBefore(Or, TheAnd);
return BinaryOperator::createAnd(Or, AndRHS);
}
}
break;
case Instruction::Add:
if (Op->hasOneUse()) {
@ -1445,27 +1509,103 @@ Instruction *InstCombiner::visitAnd(BinaryOperator &I) {
if (isa<UndefValue>(Op1)) // X & undef -> 0
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
// and X, X = X and X, 0 == 0
if (Op0 == Op1 || Op1 == Constant::getNullValue(I.getType()))
// and X, X = X
if (Op0 == Op1)
return ReplaceInstUsesWith(I, Op1);
// and X, -1 == X
if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
if (RHS->isAllOnesValue())
if (ConstantIntegral *AndRHS = dyn_cast<ConstantIntegral>(Op1)) {
if (AndRHS->isAllOnesValue()) // and X, -1 == X
return ReplaceInstUsesWith(I, Op0);
if (MaskedValueIsZero(Op0, AndRHS)) // LHS & RHS == 0
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
// If the mask is not masking out any bits, there is no reason to do the
// and in the first place.
if (MaskedValueIsZero(Op0,
cast<ConstantIntegral>(ConstantExpr::getNot(AndRHS))))
return ReplaceInstUsesWith(I, Op0);
// Optimize a variety of ((val OP C1) & C2) combinations...
if (isa<BinaryOperator>(Op0) || isa<ShiftInst>(Op0)) {
Instruction *Op0I = cast<Instruction>(Op0);
Value *X = Op0I->getOperand(0);
Value *Op0LHS = Op0I->getOperand(0);
Value *Op0RHS = Op0I->getOperand(1);
switch (Op0I->getOpcode()) {
case Instruction::Xor:
case Instruction::Or:
// (X ^ V) & C2 --> (X & C2) iff (V & C2) == 0
// (X | V) & C2 --> (X & C2) iff (V & C2) == 0
if (MaskedValueIsZero(Op0LHS, AndRHS))
return BinaryOperator::createAnd(Op0RHS, AndRHS);
if (MaskedValueIsZero(Op0RHS, AndRHS))
return BinaryOperator::createAnd(Op0LHS, AndRHS);
break;
case Instruction::And:
// (X & V) & C2 --> 0 iff (V & C2) == 0
if (MaskedValueIsZero(Op0LHS, AndRHS) ||
MaskedValueIsZero(Op0RHS, AndRHS))
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
break;
}
if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1)))
if (Instruction *Res = OptAndOp(Op0I, Op0CI, RHS, I))
if (Instruction *Res = OptAndOp(Op0I, Op0CI, AndRHS, I))
return Res;
} else if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
const Type *SrcTy = CI->getOperand(0)->getType();
// If this is an integer sign or zero extension instruction.
if (SrcTy->isIntegral() &&
SrcTy->getPrimitiveSize() < CI->getType()->getPrimitiveSize()) {
if (SrcTy->isUnsigned()) {
// See if this and is clearing out bits that are known to be zero
// anyway (due to the zero extension).
Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
Constant *Result = ConstantExpr::getAnd(Mask, AndRHS);
if (Result == Mask) // The "and" isn't doing anything, remove it.
return ReplaceInstUsesWith(I, CI);
if (Result != AndRHS) { // Reduce the and RHS constant.
I.setOperand(1, Result);
return &I;
}
} else {
if (CI->hasOneUse() && SrcTy->isInteger()) {
// We can only do this if all of the sign bits brought in are masked
// out. Compute this by first getting 0000011111, then inverting
// it.
Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy);
Mask = ConstantExpr::getZeroExtend(Mask, CI->getType());
Mask = ConstantExpr::getNot(Mask); // 1's in the new bits.
if (ConstantExpr::getAnd(Mask, AndRHS)->isNullValue()) {
// If the and is clearing all of the sign bits, change this to a
// zero extension cast. To do this, cast the cast input to
// unsigned, then to the requested size.
Value *CastOp = CI->getOperand(0);
Instruction *NC =
new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
CI->getName()+".uns");
NC = InsertNewInstBefore(NC, I);
// Finally, insert a replacement for CI.
NC = new CastInst(NC, CI->getType(), CI->getName());
CI->setName("");
NC = InsertNewInstBefore(NC, I);
WorkList.push_back(CI); // Delete CI later.
I.setOperand(0, NC);
return &I; // The AND operand was modified.
}
}
}
}
}
// Try to fold constant and into select arguments.
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
return R;
if (isa<PHINode>(Op0))
if (Instruction *NV = FoldOpIntoPhi(I))
@ -1599,8 +1739,11 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
// or X, -1 == -1
if (ConstantIntegral *RHS = dyn_cast<ConstantIntegral>(Op1)) {
if (RHS->isAllOnesValue())
return ReplaceInstUsesWith(I, Op1);
// If X is known to only contain bits that already exist in RHS, just
// replace this instruction with RHS directly.
if (MaskedValueIsZero(Op0,
cast<ConstantIntegral>(ConstantExpr::getNot(RHS))))
return ReplaceInstUsesWith(I, RHS);
ConstantInt *C1; Value *X;
// (X & C1) | C2 --> (X | C2) & (C1|C2)
@ -1622,7 +1765,7 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
// Try to fold constant and into select arguments.
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
return R;
if (isa<PHINode>(Op0))
if (Instruction *NV = FoldOpIntoPhi(I))
@ -1840,7 +1983,7 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
// Try to fold constant and into select arguments.
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
return R;
if (isa<PHINode>(Op0))
if (Instruction *NV = FoldOpIntoPhi(I))
@ -2671,7 +2814,7 @@ Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
// Try to fold constant and into select arguments.
if (isa<Constant>(Op0))
if (SelectInst *SI = dyn_cast<SelectInst>(Op1))
if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
return R;
if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(Op1)) {
@ -2697,15 +2840,48 @@ Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
// Try to fold constant and into select arguments.
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldBinOpIntoSelect(I, SI, this))
if (Instruction *R = FoldOpIntoSelect(I, SI, this))
return R;
if (isa<PHINode>(Op0))
if (Instruction *NV = FoldOpIntoPhi(I))
return NV;
if (Op0->hasOneUse()) {
// If this is a SHL of a sign-extending cast, see if we can turn the input
// into a zero extending cast (a simple strength reduction).
if (CastInst *CI = dyn_cast<CastInst>(Op0)) {
const Type *SrcTy = CI->getOperand(0)->getType();
if (isLeftShift && SrcTy->isInteger() && SrcTy->isSigned() &&
SrcTy->getPrimitiveSize() < CI->getType()->getPrimitiveSize()) {
// We can change it to a zero extension if we are shifting out all of
// the sign extended bits. To check this, form a mask of all of the
// sign extend bits, then shift them left and see if we have anything
// left.
Constant *Mask = ConstantIntegral::getAllOnesValue(SrcTy); // 1111
Mask = ConstantExpr::getZeroExtend(Mask, CI->getType()); // 00001111
Mask = ConstantExpr::getNot(Mask); // 1's in the sign bits: 11110000
if (ConstantExpr::getShl(Mask, CUI)->isNullValue()) {
// If the shift is nuking all of the sign bits, change this to a
// zero extension cast. To do this, cast the cast input to
// unsigned, then to the requested size.
Value *CastOp = CI->getOperand(0);
Instruction *NC =
new CastInst(CastOp, CastOp->getType()->getUnsignedVersion(),
CI->getName()+".uns");
NC = InsertNewInstBefore(NC, I);
// Finally, insert a replacement for CI.
NC = new CastInst(NC, CI->getType(), CI->getName());
CI->setName("");
NC = InsertNewInstBefore(NC, I);
WorkList.push_back(CI); // Delete CI later.
I.setOperand(0, NC);
return &I; // The SHL operand was modified.
}
}
}
// If the operand is an bitwise operator with a constant RHS, and the
// shift is the only use, we can pull it out of the shift.
if (Op0->hasOneUse())
if (BinaryOperator *Op0BO = dyn_cast<BinaryOperator>(Op0))
if (ConstantInt *Op0C = dyn_cast<ConstantInt>(Op0BO->getOperand(1))) {
bool isValid = true; // Valid only for And, Or, Xor
@ -2749,6 +2925,7 @@ Instruction *InstCombiner::visitShiftInst(ShiftInst &I) {
NewRHS);
}
}
}
// If this is a shift of a shift, see if we can fold the two together...
if (ShiftInst *Op0SI = dyn_cast<ShiftInst>(Op0))
@ -2926,9 +3103,10 @@ Instruction *InstCombiner::visitCastInst(CastInst &CI) {
// If casting the result of another cast instruction, try to eliminate this
// one!
//
if (CastInst *CSrc = dyn_cast<CastInst>(Src)) {
if (isEliminableCastOfCast(CSrc->getOperand(0)->getType(),
CSrc->getType(), CI.getType(), TD)) {
if (CastInst *CSrc = dyn_cast<CastInst>(Src)) { // A->B->C cast
Value *A = CSrc->getOperand(0);
if (isEliminableCastOfCast(A->getType(), CSrc->getType(),
CI.getType(), TD)) {
// This instruction now refers directly to the cast's src operand. This
// has a good chance of making CSrc dead.
CI.setOperand(0, CSrc->getOperand(0));
@ -2938,15 +3116,24 @@ Instruction *InstCombiner::visitCastInst(CastInst &CI) {
// If this is an A->B->A cast, and we are dealing with integral types, try
// to convert this into a logical 'and' instruction.
//
if (CSrc->getOperand(0)->getType() == CI.getType() &&
if (A->getType()->isInteger() &&
CI.getType()->isInteger() && CSrc->getType()->isInteger() &&
CI.getType()->isUnsigned() && CSrc->getType()->isUnsigned() &&
CSrc->getType()->getPrimitiveSize() < CI.getType()->getPrimitiveSize()){
CSrc->getType()->isUnsigned() && // B->A cast must zero extend
CSrc->getType()->getPrimitiveSize() < CI.getType()->getPrimitiveSize()&&
A->getType()->getPrimitiveSize() == CI.getType()->getPrimitiveSize()) {
assert(CSrc->getType() != Type::ULongTy &&
"Cannot have type bigger than ulong!");
uint64_t AndValue = (1ULL << CSrc->getType()->getPrimitiveSize()*8)-1;
Constant *AndOp = ConstantUInt::get(CI.getType(), AndValue);
return BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
Constant *AndOp = ConstantUInt::get(A->getType()->getUnsignedVersion(),
AndValue);
AndOp = ConstantExpr::getCast(AndOp, A->getType());
Instruction *And = BinaryOperator::createAnd(CSrc->getOperand(0), AndOp);
if (And->getType() != CI.getType()) {
And->setName(CSrc->getName()+".mask");
InsertNewInstBefore(And, CI);
And = new CastInst(And, CI.getType());
}
return And;
}
}
@ -3001,6 +3188,9 @@ Instruction *InstCombiner::visitCastInst(CastInst &CI) {
}
}
if (SelectInst *SI = dyn_cast<SelectInst>(Src))
if (Instruction *NV = FoldOpIntoSelect(CI, SI, this))
return NV;
if (isa<PHINode>(Src))
if (Instruction *NV = FoldOpIntoPhi(CI))
return NV;