[X86] canonicalizeShuffleWithOp - pull out repeated flag settings to IsMergeableWithShuffle lambda. NFC.

Prep work before tweaking the flags in a future patch.

Author: RKSimon

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -41598,10 +41598,10 @@ static SDValue canonicalizeShuffleWithOp(SDValue N, SelectionDAG &DAG,
       if (TLI.isBinOp(SrcOpcode) && IsSafeToMoveShuffle(N0, SrcOpcode)) {
         SDValue Op00 = peekThroughOneUseBitcasts(N0.getOperand(0));
         SDValue Op01 = peekThroughOneUseBitcasts(N0.getOperand(1));
-        if (IsMergeableWithShuffle(Op00, Opc != X86ISD::VPERMI,
-                                   Opc != X86ISD::PSHUFB) ||
-            IsMergeableWithShuffle(Op01, Opc != X86ISD::VPERMI,
-                                   Opc != X86ISD::PSHUFB)) {
+        bool FoldShuf = Opc != X86ISD::VPERMI;
+        bool FoldLoad = Opc != X86ISD::PSHUFB;
+        if (IsMergeableWithShuffle(Op00, FoldShuf, FoldLoad) ||
+            IsMergeableWithShuffle(Op01, FoldShuf, FoldLoad)) {
           SDValue LHS, RHS;
           Op00 = DAG.getBitcast(ShuffleVT, Op00);
           Op01 = DAG.getBitcast(ShuffleVT, Op01);