[libc-commits] [libc] [libc][math] Qualify fdim funtions to constexpr (PR #194137)

[Muhammad Bassiouni via libc-commits]

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@@ -117,10 +126,17 @@ add_or_sub(InType x, InType y) {
         // volatile prevents Clang from converting tmp to OutType and then
         // immediately back to InType before negating it, resulting in double
         // rounding.
-        volatile InType tmp = y;
-        if constexpr (IsSub)
-          tmp = -tmp;
-        return cast<OutType>(tmp);
+        if (__builtin_is_constant_evaluated()) {
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bassiounix wrote:

```suggestion
        if (cpp::is_constant_evaluated()) {
```

https://github.com/llvm/llvm-project/pull/194137