[clang] [clang] Add builtins for `add` with `nuw` and/or `nsw` (PR #130354)

[Nikolas Klauser via cfe-commits]

================
@@ -5037,6 +5037,66 @@ def ArithmeticFence : LangBuiltin<"ALL_LANGUAGES"> {
   let Prototype = "void(...)";
 }
 
+class SNUWTemplate :
+  Template<["int",      "long int",  "long long int"],
+           ["_nuw",     "l_nuw",     "ll_nuw"]>;
+
+class SNSWTemplate :
+  Template<["int",      "long int",  "long long int"],
+           ["_nsw",     "l_nsw",     "ll_nsw"]>;
+
+class SNXWTemplate :
+  Template<["int",      "long int",  "long long int"],
+           ["_nuw_nsw", "l_nuw_nsw", "ll_nuw_nsw"]>;
+
+def SAddNUW : Builtin, SNUWTemplate {
+  let Spellings = ["__builtin_sadd"];
+  let Attributes = [NoThrow];
+  let Prototype = "T(T const, T const)";
----------------
philnik777 wrote:

```suggestion
  let Prototype = "T(T, T)";
```
These don't do anything anyways, so we might as well drop them.

https://github.com/llvm/llvm-project/pull/130354