[llvm] r360579 - TargetLowering::SimplifyDemandedBits - early-out for UNDEF ops. NFCI.
Simon Pilgrim via llvm-commits
llvm-commits at lists.llvm.org
Mon May 13 05:44:04 PDT 2019
Author: rksimon
Date: Mon May 13 05:44:03 2019
New Revision: 360579
URL: http://llvm.org/viewvc/llvm-project?rev=360579&view=rev
Log:
TargetLowering::SimplifyDemandedBits - early-out for UNDEF ops. NFCI.
Modified:
llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp?rev=360579&r1=360578&r2=360579&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/TargetLowering.cpp Mon May 13 05:44:03 2019
@@ -588,6 +588,10 @@ bool TargetLowering::SimplifyDemandedBit
// Don't know anything.
Known = KnownBits(BitWidth);
+ // Undef operand.
+ if (Op.isUndef())
+ return false;
+
if (Op.getOpcode() == ISD::Constant) {
// We know all of the bits for a constant!
Known.One = cast<ConstantSDNode>(Op)->getAPIntValue();
@@ -610,9 +614,7 @@ bool TargetLowering::SimplifyDemandedBit
DemandedElts = APInt::getAllOnesValue(NumElts);
} else if (OriginalDemandedBits == 0 || OriginalDemandedElts == 0) {
// Not demanding any bits/elts from Op.
- if (!Op.isUndef())
- return TLO.CombineTo(Op, TLO.DAG.getUNDEF(VT));
- return false;
+ return TLO.CombineTo(Op, TLO.DAG.getUNDEF(VT));
} else if (Depth == 6) { // Limit search depth.
return false;
}
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