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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/113679] long long minus double with gcc -m32 produces different results than other compilers or gcc -m64
Date: Wed, 31 Jan 2024 08:53:56 +0000	[thread overview]
Message-ID: <bug-113679-4-TrzhHfhCVo@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-113679-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113679

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Yeah, it is, that is how excess precision behaves.
Due to the cast applying just to l rather than l - d it returns 0.0 with
-fexcess-precision=standard, but if you change it to (double)(l - d) then it
will return -2.0
at all optimization levels with -fexcess-precision=standard. 
-fexcess-precision=fast
behaves depending on what instructions are actually used and where the
conversions to float or double happen due to storing of expressions or
subexpressions into memory as documented.
If you don't like excess precision and have SSE2, you can use -msse2
-mfpmath=sse.

  parent reply	other threads:[~2024-01-31  8:53 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-31  8:40 [Bug c/113679] New: " dilyan.palauzov at aegee dot org
2024-01-31  8:44 ` [Bug target/113679] " pinskia at gcc dot gnu.org
2024-01-31  8:45 ` dilyan.palauzov at aegee dot org
2024-01-31  8:52 ` pinskia at gcc dot gnu.org
2024-01-31  8:53 ` jakub at gcc dot gnu.org [this message]
2024-01-31  9:58 ` dilyan.palauzov at aegee dot org
2024-01-31 10:02 ` pinskia at gcc dot gnu.org
2024-01-31 10:26 ` jakub at gcc dot gnu.org
2024-01-31 14:32 ` dilyan.palauzov at aegee dot org
2024-01-31 14:35 ` jakub at gcc dot gnu.org
2024-01-31 14:38 ` jakub at gcc dot gnu.org
2024-01-31 15:53 ` jakub at gcc dot gnu.org
2024-02-07  5:55 ` egallager at gcc dot gnu.org
2024-02-10 14:32 ` dilyan.palauzov at aegee dot org

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