[llvm] a6f35d1 - [X86] combineTargetShuffle - remove redundant INSERTPS demanded mask fold (#217576)

[via llvm-commits]

Author: Simon Pilgrim
Date: 2026-08-20T11:16:57Z
New Revision: a6f35d1c87513614baaa2f626257e8d4b8320fef

URL: https://github.com/llvm/llvm-project/commit/a6f35d1c87513614baaa2f626257e8d4b8320fef
DIFF: https://github.com/llvm/llvm-project/commit/a6f35d1c87513614baaa2f626257e8d4b8320fef.diff

LOG: [X86] combineTargetShuffle - remove redundant INSERTPS demanded mask fold (#217576)

This is handled more generally in SimplifyDemandedVectorEltsForTargetNode

Added: 
    

Modified: 
    llvm/lib/Target/X86/X86ISelLowering.cpp

Removed: 
    


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diff  --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 6144e1f0bf99d..406761eec9721 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -43797,16 +43797,6 @@ static SDValue combineTargetShuffle(SDValue N, const SDLoc &DL,
     unsigned DstIdx = (InsertPSMask >> 4) & 0x3;
     unsigned ZeroMask = InsertPSMask & 0xF;
 
-    // If we zero out all elements from Op0 then we don't need to reference it.
-    if (((ZeroMask | (1u << DstIdx)) == 0xF) && !Op0.isUndef())
-      return DAG.getNode(X86ISD::INSERTPS, DL, VT, DAG.getUNDEF(VT), Op1,
-                         DAG.getTargetConstant(InsertPSMask, DL, MVT::i8));
-
-    // If we zero out the element from Op1 then we don't need to reference it.
-    if ((ZeroMask & (1u << DstIdx)) && !Op1.isUndef())
-      return DAG.getNode(X86ISD::INSERTPS, DL, VT, Op0, DAG.getUNDEF(VT),
-                         DAG.getTargetConstant(InsertPSMask, DL, MVT::i8));
-
     // Chained inserts of the same src - prefer splat + blend.
     // TODO: Splat isn't necessary if they insert into 
diff erent v2f32 subs.
     if (Op0.getOpcode() == X86ISD::INSERTPS && Op0.getOperand(1) == Op1) {