[DAG] MaskedVectorIsZero - don't bother with (-1).isSubsetOf mask che…

…ck. NFC. Just use KnownBits::isZero() to ensure all the bits are known zero.
llvm · Jul 24, 2022 · 0708771 · 0708771
1 parent e82d49b
commit 0708771
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Showing 2 changed files with 4 additions and 5 deletions.
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2529,8 +2529,7 @@ bool SelectionDAG::MaskedValueIsZero(SDValue V, const APInt &Mask,
 /// DemandedElts.  We use this predicate to simplify operations downstream.
 bool SelectionDAG::MaskedVectorIsZero(SDValue V, const APInt &DemandedElts,
                                       unsigned Depth /* = 0 */) const {
-  APInt Mask = APInt::getAllOnes(V.getScalarValueSizeInBits());
-  return Mask.isSubsetOf(computeKnownBits(V, DemandedElts, Depth).Zero);
+  return computeKnownBits(V, DemandedElts, Depth).isZero();
 }
 
 /// MaskedValueIsAllOnes - Return true if '(Op & Mask) == Mask'.

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -37522,8 +37522,8 @@ static bool matchBinaryShuffle(MVT MaskVT, ArrayRef<int> Mask,
       break;
     }
     if (IsBlend) {
-      if (DAG.computeKnownBits(V1, DemandedZeroV1).isZero() &&
-          DAG.computeKnownBits(V2, DemandedZeroV2).isZero()) {
+      if (DAG.MaskedVectorIsZero(V1, DemandedZeroV1) &&
+          DAG.MaskedVectorIsZero(V2, DemandedZeroV2)) {
         Shuffle = ISD::OR;
         SrcVT = DstVT = MaskVT.changeTypeToInteger();
         return true;
@@ -41191,7 +41191,7 @@ bool X86TargetLowering::SimplifyDemandedVectorEltsForTargetNode(
     SDValue Src = Op.getOperand(0);
     APInt DemandedUpperElts = DemandedElts;
     DemandedUpperElts.clearLowBits(1);
-    if (TLO.DAG.computeKnownBits(Src, DemandedUpperElts, Depth + 1).isZero())
+    if (TLO.DAG.MaskedVectorIsZero(Src, DemandedUpperElts, Depth + 1))
       return TLO.CombineTo(Op, Src);
     break;
   }