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[X86] Remove ANY_EXTEND special case from canReduceVMulWidth 

Removing this code doesn't affect any lit tests so it doesn't appear to be tested anymore. I assume it was when it was added, but I guess something else changed? Code coverage report also says its unused.

I mostly didn't like that it seemed to count the sign bits as if it was a sign_extend, but then set isPositive as if it was a zero_extend. It feels like we should have picked one interpretation?

Differential Revision: https://reviews.llvm.org/D54596

llvm-svn: 346995
This commit is contained in:
Craig Topper 2018-11-15 21:19:32 +00:00
parent 04f9d0a0c3
commit 22bfa99448
1 changed files with 2 additions and 18 deletions
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20
llvm/lib/Target/X86/X86ISelLowering.cpp
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@ -34337,24 +34337,8 @@ static bool canReduceVMulWidth(SDNode *N, SelectionDAG &DAG, ShrinkMode &Mode) {
for (unsigned i = 0; i < 2; i++) {
SDValue Opd = N->getOperand(i);
// DAG.ComputeNumSignBits return 1 for ISD::ANY_EXTEND, so we need to
// compute signbits for it separately.
if (Opd.getOpcode() == ISD::ANY_EXTEND) {
// For anyextend, it is safe to assume an appropriate number of leading
// sign/zero bits.
if (Opd.getOperand(0).getValueType().getVectorElementType() == MVT::i8)
SignBits[i] = 25;
else if (Opd.getOperand(0).getValueType().getVectorElementType() ==
MVT::i16)
SignBits[i] = 17;
else
return false;
IsPositive[i] = true;
} else {
SignBits[i] = DAG.ComputeNumSignBits(Opd);
if (DAG.SignBitIsZero(Opd))
IsPositive[i] = true;
}
SignBits[i] = DAG.ComputeNumSignBits(Opd);
IsPositive[i] = DAG.SignBitIsZero(Opd);
}
bool AllPositive = IsPositive[0] && IsPositive[1];