[X86] combineConcatVectorOps - add missing VT/Subtarget checks for MOV*DUP concatenation folds.

Author: RKSimon

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -58012,7 +58012,8 @@ static SDValue combineConcatVectorOps(const SDLoc &DL, MVT VT,
     case X86ISD::MOVDDUP:
     case X86ISD::MOVSHDUP:
     case X86ISD::MOVSLDUP: {
-      if (!IsSplat)
+      if (!IsSplat && (VT.is256BitVector() ||
+                       (VT.is512BitVector() && Subtarget.useAVX512Regs())))
         return DAG.getNode(Op0.getOpcode(), DL, VT,
                            ConcatSubOperand(VT, Ops, 0));
       break;