[clang] [Clang] Add float type support to __builtin_reduce_add and __builtin_reduce_multipy (PR #120367)

[Farzon Lotfi via cfe-commits]

================
@@ -1754,6 +1755,17 @@ static bool interp__builtin_vector_reduce(InterpState &S, CodePtr OpPC,
   PrimType ElemT = *S.getContext().classify(ElemType);
   unsigned NumElems = Arg.getNumElems();
 
+  if (ElemType->isRealFloatingType()) {
+    if (ID != Builtin::BI__builtin_reduce_add &&
+        ID != Builtin::BI__builtin_reduce_mul)
+      llvm_unreachable("Only reduce_add and reduce_mul are supported for "
----------------
farzonl wrote:

Context the float case was exposed by the changes in SemaChecking.cpp which allowed `reduce_add` and `reduce_mul`  to operate on floating point vectors. The remaining reduce builtins `Builtin::BI__builtin_reduce_xor, `Builtin::BI__builtin_reduce_or`, and `Builtin::BI__builtin_reduce_and` are not reachable here because the integer checks in SemaChecking.cpp  still apply to them. So yes this branch should be unreachable for all non `reduce_add` and `reduce_mul` reduction cases.

https://github.com/llvm/llvm-project/pull/120367