[libc++] simplify the midpoint function

[rilysh]

Right now we've a nested ternary for the midpoint function, but this can be simplified a bit more, using if statements. This also slightly increases the readability of that function.

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[llvmbot]

@llvm/pr-subscribers-libcxx

Author: None (rilysh)

Changes

Right now we've a nested ternary for the midpoint function, but this can be simplified a bit more, using if..else. This also slightly increases the readability of that function.

---

Full diff: https://github.com/llvm/llvm-project/pull/81717.diff

1 Files Affected:

• (modified) libcxx/include/__numeric/midpoint.h (+10-8)

diff --git a/libcxx/include/__numeric/midpoint.h b/libcxx/include/__numeric/midpoint.h
index 5d715c21d8eaca..4232610ce27be4 100644
--- a/libcxx/include/__numeric/midpoint.h
+++ b/libcxx/include/__numeric/midpoint.h
@@ -67,14 +67,16 @@ template <class _Fp>
 _LIBCPP_HIDE_FROM_ABI constexpr enable_if_t<is_floating_point_v<_Fp>, _Fp> midpoint(_Fp __a, _Fp __b) noexcept {
   constexpr _Fp __lo = numeric_limits<_Fp>::min() * 2;
   constexpr _Fp __hi = numeric_limits<_Fp>::max() / 2;
-  return std::__fp_abs(__a) <= __hi && std::__fp_abs(__b) <= __hi
-           ? // typical case: overflow is impossible
-             (__a + __b) / 2
-           :                                             // always correctly rounded
-             std::__fp_abs(__a) < __lo ? __a + __b / 2 : // not safe to halve a
-                 std::__fp_abs(__b) < __lo ? __a / 2 + __b
-                                           : // not safe to halve b
-                 __a / 2 + __b / 2;          // otherwise correctly rounded
+
+  // typical case: overflow is impossible
+  if (std::__fp_abs(__a) <= __hi && std::__fp_abs(__b) <= __hi)
+    return (__a + __b) / 2; // always correctly rounded
+  else if (std::__fp_abs(__a) < __lo)
+    return __a + __b / 2; // not safe to halve a
+  else if (std::__fp_abs(__b) < __lo)
+    return __a / 2 + __b; // not safe to halve b
+  else
+    return __a / 2 + __b / 2; // otherwise correctly rounded
 }
 
 #endif // _LIBCPP_STD_VER >= 20

[philnik777]

Is this doing anything other than making the code more readable?

[rilysh]

Is this doing anything other than making the code more readable?

No. It isn't doing anything more than the title says.

[mordante]

Thanks for working on this, it indeed improves readability.

[mordante]

Thanks for your contribution, LGTM!

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