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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/103559] Can't optimize away < 0 check on sqrt
Date: Thu, 30 Mar 2023 11:41:23 +0000	[thread overview]
Message-ID: <bug-103559-4-B3vGs6YKL7@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-103559-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103559

--- Comment #11 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Actually, I was just misreading the tree dumps, we use hw insn for x u>= 0.0,
which
is UNGE_EXPR, so it is true if x is NAN or GE_EXPR, or as described in the
tree-call-cdce.cc comment:
        y = sqrt (x);
     ==>
        if (__builtin_isless (x, 0))
          y =  sqrt (x);
        else
          y = IFN_SQRT (x);
So we don't need to inspect anything on the libc sides, we already use the hw
insn even for NANs.
All we need to do is to use the ranger in tree-call-cdce.cc or perhaps later,
and fold the x UNGE_EXPR 0.0 into true whenever frange says so (i.e. that the
range is a subset
of [-0.0, +INF] NAN).

      parent reply	other threads:[~2023-03-30 11:41 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-04 20:58 [Bug tree-optimization/103559] New: " llvm at rifkin dot dev
2021-12-04 21:01 ` [Bug tree-optimization/103559] " pinskia at gcc dot gnu.org
2021-12-04 21:34 ` pinskia at gcc dot gnu.org
2021-12-04 21:38 ` pinskia at gcc dot gnu.org
2021-12-04 21:43 ` pinskia at gcc dot gnu.org
2021-12-05 11:38 ` vanyacpp at gmail dot com
2023-03-29 17:46 ` aldyh at gcc dot gnu.org
2023-03-29 18:34 ` llvm at rifkin dot dev
2023-03-29 18:39 ` jakub at gcc dot gnu.org
2023-03-30 10:40 ` xry111 at gcc dot gnu.org
2023-03-30 10:48 ` jakub at gcc dot gnu.org
2023-03-30 10:53 ` xry111 at gcc dot gnu.org
2023-03-30 11:41 ` jakub at gcc dot gnu.org [this message]

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