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implement and.ll:test30 and set.ll:test21

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21712 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-05-06 01:53:19 +00:00
parent cb94575bc6
commit d152380ba8
1 changed files with 60 additions and 18 deletions
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78
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -1340,21 +1340,23 @@ static bool MaskedValueIsZero(Value *V, ConstantIntegral *Mask) {
MaskedValueIsZero(I->getOperand(1), Mask);
case Instruction::Cast: {
const Type *SrcTy = I->getOperand(0)->getType();
if (SrcTy->isIntegral()) {
if (SrcTy == Type::BoolTy)
return (Mask->getRawValue() & 1) == 0;
if (SrcTy->isInteger()) {
// (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));
}
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;
}
@ -3561,24 +3563,64 @@ Instruction *InstCombiner::visitCastInst(CastInst &CI) {
}
break;
case Instruction::SetNE:
case Instruction::SetEQ:
// We if we are just checking for a seteq of a single bit and casting it
// to an integer. If so, shift the bit to the appropriate place then
// cast to integer to avoid the comparison.
if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
// cast (X != 0) to int, cast (X == 1) to int -> X iff X has only the
// low bit set.
bool isSetNE = SrcI->getOpcode() == Instruction::SetNE;
if ((isSetNE && Op1C->getRawValue() == 0) ||
(!isSetNE && Op1C->getRawValue() == 1)) {
if (Op1C->getRawValue() == 0) {
// If the input only has the low bit set, simplify directly.
Constant *Not1 =
ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
// cast (X != 0) to int --> X if X&~1 == 0
if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
if (CI.getType() == Op0->getType())
return ReplaceInstUsesWith(CI, Op0);
else
return new CastInst(Op0, CI.getType());
}
// If the input is an and with a single bit, shift then simplify.
ConstantInt *AndRHS;
if (match(Op0, m_And(m_Value(), m_ConstantInt(AndRHS))))
if (AndRHS->getRawValue() &&
(AndRHS->getRawValue() & (AndRHS->getRawValue()-1)) == 0) {
unsigned ShiftAmt = Log2(AndRHS->getRawValue());
// Perform an unsigned shr by shiftamt. Convert input to
// unsigned if it is signed.
Value *In = Op0;
if (In->getType()->isSigned())
In = InsertNewInstBefore(new CastInst(In,
In->getType()->getUnsignedVersion(), In->getName()),CI);
// Insert the shift to put the result in the low bit.
In = InsertNewInstBefore(new ShiftInst(Instruction::Shr, In,
ConstantInt::get(Type::UByteTy, ShiftAmt),
In->getName()+".lobit"), CI);
std::cerr << "In1 = " << *Op0;
std::cerr << "In2 = " << *CI.getOperand(0);
std::cerr << "In3 = " << CI;
if (CI.getType() == In->getType())
return ReplaceInstUsesWith(CI, In);
else
return new CastInst(In, CI.getType());
}
}
}
break;
case Instruction::SetEQ:
// We if we are just checking for a seteq of a single bit and casting it
// to an integer. If so, shift the bit to the appropriate place then
// cast to integer to avoid the comparison.
if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) {
// Is Op1C a power of two or zero?
if ((Op1C->getRawValue() & Op1C->getRawValue()-1) == 0) {
// cast (X == 1) to int -> X iff X has only the low bit set.
if (Op1C->getRawValue() == 1) {
Constant *Not1 =
ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1));
if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) {
if (CI.getType() == Op0->getType())
return ReplaceInstUsesWith(CI, Op0);
else
return new CastInst(Op0, CI.getType());
}
}
}
}
break;