[llvm] [SDAG] Harden assumption in getMemsetStringVal (PR #126207)

[Matt Arsenault via llvm-commits]

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@@ -8015,16 +8015,8 @@ static SDValue getMemsetStringVal(EVT VT, const SDLoc &dl, SelectionDAG &DAG,
   if (Slice.Array == nullptr) {
     if (VT.isInteger())
       return DAG.getConstant(0, dl, VT);
-    if (VT == MVT::f32 || VT == MVT::f64 || VT == MVT::f128)
+    if (VT.isFloatingPoint())
       return DAG.getConstantFP(0.0, dl, VT);
-    if (VT.isVector()) {
-      unsigned NumElts = VT.getVectorNumElements();
-      MVT EltVT = (VT.getVectorElementType() == MVT::f32) ? MVT::i32 : MVT::i64;
-      return DAG.getNode(ISD::BITCAST, dl, VT,
-                         DAG.getConstant(0, dl,
-                                         EVT::getVectorVT(*DAG.getContext(),
-                                                          EltVT, NumElts)));
-    }
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arsenm wrote:

I mean instead of having this unreachable case 

https://github.com/llvm/llvm-project/pull/126207