[llvm] [X86] Handle shifts + and in `LowerSELECTWithCmpZero` (PR #107910)

[Simon Pilgrim via llvm-commits]

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@@ -24136,15 +24141,40 @@ static SDValue LowerSELECTWithCmpZero(SDValue CmpVal, SDValue LHS, SDValue RHS,
       return false;
     };
 
+    auto isIdentityPatternOnes = [&]() {
+      switch (LHS.getOpcode()) {
+      default:
+        break;
+      case ISD::AND:
+        if (LHS.getOperand(0) == RHS || LHS.getOperand(1) == RHS) {
+          Src1 = LHS.getOperand(LHS.getOperand(0) == RHS ? 1 : 0);
+          Src2 = RHS;
+          return true;
+        }
+        break;
+      }
+      return false;
+    };
+
     // Convert 'identity' patterns (iff X is 0 or 1):
     // SELECT (AND(X,1) == 0), Y, (OR Y, Z) -> (OR Y, (AND NEG(AND(X,1)), Z))
     // SELECT (AND(X,1) == 0), Y, (XOR Y, Z) -> (XOR Y, (AND NEG(AND(X,1)), Z))
     // SELECT (AND(X,1) == 0), Y, (ADD Y, Z) -> (ADD Y, (AND NEG(AND(X,1)), Z))
     // SELECT (AND(X,1) == 0), Y, (SUB Y, Z) -> (SUB Y, (AND NEG(AND(X,1)), Z))
-    if (!Subtarget.canUseCMOV() && isIdentityPattern()) {
-      SDValue Mask = SplatLSB();
-      SDValue And = DAG.getNode(ISD::AND, DL, VT, Mask, Src1); // Mask & z
-      return DAG.getNode(RHS.getOpcode(), DL, VT, Src2, And);  // y Op And
+    // SELECT (AND(X,1) == 0), Y, (SHL Y, Z) -> (SHL Y, (AND NEG(AND(X,1)), Z))
+    // SELECT (AND(X,1) == 0), Y, (SRA Y, Z) -> (SRA Y, (AND NEG(AND(X,1)), Z))
+    // SELECT (AND(X,1) == 0), Y, (SRL Y, Z) -> (SRL Y, (AND NEG(AND(X,1)), Z))
+    if (!Subtarget.canUseCMOV() && isIdentityPatternZero()) {
+      SDValue Mask = SplatLSB(Src1.getValueType());
+      SDValue And = DAG.getNode(ISD::AND, DL, Src1.getValueType(), Mask,
+                                Src1); // Mask & z
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RKSimon wrote:

@goldsteinn clang-format this

https://github.com/llvm/llvm-project/pull/107910