Fix SimplifyDemandedBits' AssertZext logic to demand all the bits. It
needs to demand the high bits because it's asserting that they're zero.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105406 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 44a80d3..1cca100 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1498,13 +1498,17 @@
break;
}
case ISD::AssertZext: {
- EVT VT = cast<VTSDNode>(Op.getOperand(1))->getVT();
- APInt InMask = APInt::getLowBitsSet(BitWidth,
- VT.getSizeInBits());
- if (SimplifyDemandedBits(Op.getOperand(0), InMask & NewMask,
+ // Demand all the bits of the input that are demanded in the output.
+ // The low bits are obvious; the high bits are demanded because we're
+ // asserting that they're zero here.
+ if (SimplifyDemandedBits(Op.getOperand(0), NewMask,
KnownZero, KnownOne, TLO, Depth+1))
return true;
assert((KnownZero & KnownOne) == 0 && "Bits known to be one AND zero?");
+
+ EVT VT = cast<VTSDNode>(Op.getOperand(1))->getVT();
+ APInt InMask = APInt::getLowBitsSet(BitWidth,
+ VT.getSizeInBits());
KnownZero |= ~InMask & NewMask;
break;
}