[X86] combinePMULH - pull out repeated IsTruncateFree helper. NFC.

Author: RKSimon

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -53021,12 +53021,12 @@ static SDValue combinePMULH(SDValue Src, EVT VT, const SDLoc &DL,
     return SDValue();
 
   // Check if both inputs are extensions, which will be removed by truncation.
-  bool IsTruncateFree = (LHS.getOpcode() == ISD::SIGN_EXTEND ||
-                         LHS.getOpcode() == ISD::ZERO_EXTEND) &&
-                        (RHS.getOpcode() == ISD::SIGN_EXTEND ||
-                         RHS.getOpcode() == ISD::ZERO_EXTEND) &&
-                        LHS.getOperand(0).getScalarValueSizeInBits() <= 16 &&
-                        RHS.getOperand(0).getScalarValueSizeInBits() <= 16;
+  auto isOpTruncateFree = [](SDValue Op) {
+    return (Op.getOpcode() == ISD::SIGN_EXTEND ||
+            Op.getOpcode() == ISD::ZERO_EXTEND) &&
+           Op.getOperand(0).getScalarValueSizeInBits() <= 16;
+  };
+  bool IsTruncateFree = isOpTruncateFree(LHS) && isOpTruncateFree(RHS);
 
   // For AVX2+ targets, with the upper bits known zero, we can perform MULHU on
   // the (bitcasted) inputs directly, and then cheaply pack/truncate the result