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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/109758] std::abs(__float128) doesn't support NaN
Date: Sun, 07 May 2023 10:04:27 +0000	[thread overview]
Message-ID: <bug-109758-4-50Fq3iaDy2@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-109758-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109758

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
What does the committee have to do with the GCC implementation?

I guess what we could do is:
--- libstdc++-v3/include/bits/std_abs.h 2023-01-16 11:52:16.917721774 +0100
+++ libstdc++-v3/include/bits/std_abs.h 2023-05-07 12:01:03.716627026 +0200
@@ -135,7 +135,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   __extension__ inline _GLIBCXX_CONSTEXPR
   __float128
   abs(__float128 __x)
-  { return __x < 0 ? -__x : __x; }
+  {
+#if __has_builtin(__builtin_fabsf128)
+    return  __builtin_fabsf128(__x);
+#else
+    return __x < 0 ? -__x : __x;
+#endif
+  }
 #endif

 _GLIBCXX_END_NAMESPACE_VERSION
If the builtin isn't supported, perhaps we could use bit_cast if supported to
toggle the sign bit if we know where it is, but if that isn't supported either,
there is nothing we can do, as the function needs to be constexpr.

  parent reply	other threads:[~2023-05-07 10:04 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-06 17:44 [Bug libquadmath/109758] New: quadmath abs g.peterhoff@t-online.de
2023-05-06 20:33 ` [Bug libstdc++/109758] " jakub at gcc dot gnu.org
2023-05-06 22:15 ` [Bug libstdc++/109758] std::abs(__float128) doesn't support NaN redi at gcc dot gnu.org
2023-05-06 22:48 ` g.peterhoff@t-online.de
2023-05-06 22:57 ` redi at gcc dot gnu.org
2023-05-06 23:06 ` g.peterhoff@t-online.de
2023-05-06 23:09 ` redi at gcc dot gnu.org
2023-05-07  0:09 ` g.peterhoff@t-online.de
2023-05-07 10:04 ` jakub at gcc dot gnu.org [this message]
2023-05-08  8:29 ` redi at gcc dot gnu.org
2023-05-08  8:31 ` redi at gcc dot gnu.org
2023-05-08  8:47 ` jakub at gcc dot gnu.org
2023-05-08 16:40 ` redi at gcc dot gnu.org
2023-05-11 11:55 ` cvs-commit at gcc dot gnu.org
2023-05-11 11:57 ` redi at gcc dot gnu.org
2023-05-11 12:12 ` redi at gcc dot gnu.org
2023-06-01 22:44 ` cvs-commit at gcc dot gnu.org
2023-06-01 22:45 ` redi at gcc dot gnu.org
2024-03-18 14:05 ` cvs-commit at gcc dot gnu.org
2024-03-18 14:12 ` redi at gcc dot gnu.org

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