[llvm] 19ee264 - [DAG] SimplifyDemandedBits - update (or (and X, C1), (and (or X, Y), C2)) fold with sd_match (#216012)

[via llvm-commits]

Author: Simon Pilgrim
Date: 2026-08-13T14:39:06Z
New Revision: 19ee26437bee27f96ddbeec222e5a2eb2c4530a7

URL: https://github.com/llvm/llvm-project/commit/19ee26437bee27f96ddbeec222e5a2eb2c4530a7
DIFF: https://github.com/llvm/llvm-project/commit/19ee26437bee27f96ddbeec222e5a2eb2c4530a7.diff

LOG: [DAG] SimplifyDemandedBits - update (or (and X, C1), (and (or X, Y), C2)) fold with sd_match (#216012)

Cleanup some nasty commutation matching code by using sd_match

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index d85bdcadab68f..97c998b6b842c 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1642,28 +1642,16 @@ bool TargetLowering::SimplifyDemandedBits(
 
     // (or (and X, C1), (and (or X, Y), C2)) -> (or (and X, C1|C2), (and Y, C2))
     // TODO: Use SimplifyMultipleUseDemandedBits to peek through masks.
-    if (Op0.getOpcode() == ISD::AND && Op1.getOpcode() == ISD::AND &&
-        Op0->hasOneUse() && Op1->hasOneUse()) {
-      // Attempt to match all commutations - m_c_Or would've been useful!
-      for (int I = 0; I != 2; ++I) {
-        SDValue X = Op.getOperand(I).getOperand(0);
-        SDValue C1 = Op.getOperand(I).getOperand(1);
-        SDValue Alt = Op.getOperand(1 - I).getOperand(0);
-        SDValue C2 = Op.getOperand(1 - I).getOperand(1);
-        if (Alt.getOpcode() == ISD::OR) {
-          for (int J = 0; J != 2; ++J) {
-            if (X == Alt.getOperand(J)) {
-              SDValue Y = Alt.getOperand(1 - J);
-              if (SDValue C12 = TLO.DAG.FoldConstantArithmetic(ISD::OR, dl, VT,
-                                                               {C1, C2})) {
-                SDValue MaskX = TLO.DAG.getNode(ISD::AND, dl, VT, X, C12);
-                SDValue MaskY = TLO.DAG.getNode(ISD::AND, dl, VT, Y, C2);
-                return TLO.CombineTo(
-                    Op, TLO.DAG.getNode(ISD::OR, dl, VT, MaskX, MaskY));
-              }
-            }
-          }
-        }
+    SDValue X, Y, C1, C2;
+    if (sd_match(Op, m_Or(m_OneUse(m_And(m_Value(X), m_Value(C1))),
+                          m_OneUse(m_And(m_Or(m_Deferred(X), m_Value(Y)),
+                                         m_Value(C2)))))) {
+      if (SDValue C12 =
+              TLO.DAG.FoldConstantArithmetic(ISD::OR, dl, VT, {C1, C2})) {
+        SDValue MaskX = TLO.DAG.getNode(ISD::AND, dl, VT, X, C12);
+        SDValue MaskY = TLO.DAG.getNode(ISD::AND, dl, VT, Y, C2);
+        return TLO.CombineTo(Op,
+                             TLO.DAG.getNode(ISD::OR, dl, VT, MaskX, MaskY));
       }
     }