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Correct the value of LowBits in srem and urem handling in

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ComputeMaskedBits.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50692 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2008-05-06 00:51:48 +00:00
parent 703bfe6909
commit 23e1df8b8d
3 changed files with 18 additions and 9 deletions
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6
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
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@ -1560,7 +1560,7 @@ void SelectionDAG::ComputeMaskedBits(SDOperand Op, const APInt &Mask,
if (ConstantSDNode *Rem = dyn_cast<ConstantSDNode>(Op.getOperand(1))) { if (ConstantSDNode *Rem = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
APInt RA = Rem->getAPIntValue(); APInt RA = Rem->getAPIntValue();
if (RA.isPowerOf2() || (-RA).isPowerOf2()) { if (RA.isPowerOf2() || (-RA).isPowerOf2()) {
APInt LowBits = RA.isStrictlyPositive() ? ((RA - 1) | RA) : ~RA; APInt LowBits = RA.isStrictlyPositive() ? (RA - 1) : ~RA;
APInt Mask2 = LowBits | APInt::getSignBit(BitWidth); APInt Mask2 = LowBits | APInt::getSignBit(BitWidth);
ComputeMaskedBits(Op.getOperand(0), Mask2,KnownZero2,KnownOne2,Depth+1); ComputeMaskedBits(Op.getOperand(0), Mask2,KnownZero2,KnownOne2,Depth+1);
@ -1581,8 +1581,8 @@ void SelectionDAG::ComputeMaskedBits(SDOperand Op, const APInt &Mask,
case ISD::UREM: { case ISD::UREM: {
if (ConstantSDNode *Rem = dyn_cast<ConstantSDNode>(Op.getOperand(1))) { if (ConstantSDNode *Rem = dyn_cast<ConstantSDNode>(Op.getOperand(1))) {
APInt RA = Rem->getAPIntValue(); APInt RA = Rem->getAPIntValue();
if (RA.isStrictlyPositive() && RA.isPowerOf2()) { if (RA.isPowerOf2()) {
APInt LowBits = (RA - 1) | RA; APInt LowBits = (RA - 1);
APInt Mask2 = LowBits & Mask; APInt Mask2 = LowBits & Mask;
KnownZero |= ~LowBits & Mask; KnownZero |= ~LowBits & Mask;
ComputeMaskedBits(Op.getOperand(0), Mask2, KnownZero, KnownOne,Depth+1); ComputeMaskedBits(Op.getOperand(0), Mask2, KnownZero, KnownOne,Depth+1);

12
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -965,7 +965,7 @@ void InstCombiner::ComputeMaskedBits(Value *V, const APInt &Mask,
if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
APInt RA = Rem->getValue(); APInt RA = Rem->getValue();
if (RA.isPowerOf2() || (-RA).isPowerOf2()) { if (RA.isPowerOf2() || (-RA).isPowerOf2()) {
APInt LowBits = RA.isStrictlyPositive() ? ((RA - 1) | RA) : ~RA; APInt LowBits = RA.isStrictlyPositive() ? (RA - 1) : ~RA;
APInt Mask2 = LowBits | APInt::getSignBit(BitWidth); APInt Mask2 = LowBits | APInt::getSignBit(BitWidth);
ComputeMaskedBits(I->getOperand(0), Mask2,KnownZero2,KnownOne2,Depth+1); ComputeMaskedBits(I->getOperand(0), Mask2,KnownZero2,KnownOne2,Depth+1);
@ -986,8 +986,8 @@ void InstCombiner::ComputeMaskedBits(Value *V, const APInt &Mask,
case Instruction::URem: { case Instruction::URem: {
if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
APInt RA = Rem->getValue(); APInt RA = Rem->getValue();
if (RA.isStrictlyPositive() && RA.isPowerOf2()) { if (RA.isPowerOf2()) {
APInt LowBits = (RA - 1) | RA; APInt LowBits = (RA - 1);
APInt Mask2 = LowBits & Mask; APInt Mask2 = LowBits & Mask;
KnownZero |= ~LowBits & Mask; KnownZero |= ~LowBits & Mask;
ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne,Depth+1); ComputeMaskedBits(I->getOperand(0), Mask2, KnownZero, KnownOne,Depth+1);
@ -1728,7 +1728,7 @@ bool InstCombiner::SimplifyDemandedBits(Value *V, APInt DemandedMask,
if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
APInt RA = Rem->getValue(); APInt RA = Rem->getValue();
if (RA.isPowerOf2() || (-RA).isPowerOf2()) { if (RA.isPowerOf2() || (-RA).isPowerOf2()) {
APInt LowBits = RA.isStrictlyPositive() ? (RA - 1) | RA : ~RA; APInt LowBits = RA.isStrictlyPositive() ? (RA - 1) : ~RA;
APInt Mask2 = LowBits | APInt::getSignBit(BitWidth); APInt Mask2 = LowBits | APInt::getSignBit(BitWidth);
if (SimplifyDemandedBits(I->getOperand(0), Mask2, if (SimplifyDemandedBits(I->getOperand(0), Mask2,
LHSKnownZero, LHSKnownOne, Depth+1)) LHSKnownZero, LHSKnownOne, Depth+1))
@ -1749,8 +1749,8 @@ bool InstCombiner::SimplifyDemandedBits(Value *V, APInt DemandedMask,
case Instruction::URem: { case Instruction::URem: {
if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) { if (ConstantInt *Rem = dyn_cast<ConstantInt>(I->getOperand(1))) {
APInt RA = Rem->getValue(); APInt RA = Rem->getValue();
if (RA.isStrictlyPositive() && RA.isPowerOf2()) { if (RA.isPowerOf2()) {
APInt LowBits = (RA - 1) | RA; APInt LowBits = (RA - 1);
APInt Mask2 = LowBits & DemandedMask; APInt Mask2 = LowBits & DemandedMask;
KnownZero |= ~LowBits & DemandedMask; KnownZero |= ~LowBits & DemandedMask;
if (SimplifyDemandedBits(I->getOperand(0), Mask2, if (SimplifyDemandedBits(I->getOperand(0), Mask2,

9
test/Transforms/InstCombine/srem-simplify-bug.ll Normal file
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@ -0,0 +1,9 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {ret i1 false}
; PR2276
define i1 @f(i32 %x) {
%A = or i32 %x, 1
%B = srem i32 %A, 1
%C = icmp ne i32 %B, 0
ret i1 %C
}