[AVX512] No need to check for BWI being enabled before lowering v32i1…

…6 and v64i8 shuffles. If we get this far the types are already legal which means BWI must be enabled.

llvm-svn: 272449

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -11889,20 +11889,13 @@ static SDValue lower512BitVectorShuffle(SDValue Op, SDValue V1, SDValue V2,
   case MVT::v16i32:
     return lowerV16I32VectorShuffle(Op, V1, V2, Subtarget, DAG);
   case MVT::v32i16:
-    if (Subtarget.hasBWI())
-      return lowerV32I16VectorShuffle(Op, V1, V2, Subtarget, DAG);
-    break;
+    return lowerV32I16VectorShuffle(Op, V1, V2, Subtarget, DAG);
   case MVT::v64i8:
-    if (Subtarget.hasBWI())
-      return lowerV64I8VectorShuffle(Op, V1, V2, Subtarget, DAG);
-    break;
+    return lowerV64I8VectorShuffle(Op, V1, V2, Subtarget, DAG);
 
   default:
     llvm_unreachable("Not a valid 512-bit x86 vector type!");
   }
-
-  // Otherwise fall back on splitting.
-  return splitAndLowerVectorShuffle(DL, VT, V1, V2, Mask, DAG);
 }
 
 // Lower vXi1 vector shuffles.