[llvm] r360579 - TargetLowering::SimplifyDemandedBits - early-out for UNDEF ops. NFCI.

[Simon Pilgrim via llvm-commits]

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;
   }