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From: "law at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/91645] Missed optimization with sqrt(x*x)
Date: Sat, 03 Sep 2022 17:33:08 +0000	[thread overview]
Message-ID: <bug-91645-4-lX4Tf4xkGa@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-91645-4@http.gcc.gnu.org/bugzilla/>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91645

--- Comment #8 from Jeffrey A. Law <law at gcc dot gnu.org> ---
First, there's magic bits which turn a standard sqrt call into something like

if (exceptional condition)
  call libm's sqrt
else
  use hardware sqrt

The primary goal is to get errno set properly for those exceptional conditions.
 That code (tree-ssa-math-opts.cc?) can be updated to query the range to
determine if the exceptional conditions can happen.  Essentially that
eliminates the need for -fno-math-errno.

That may be enough for targets with real sqrt instructions.  More work is
likely needed for targets that use an estimator + correction steps.

  parent reply	other threads:[~2022-09-03 17:33 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <bug-91645-4@http.gcc.gnu.org/bugzilla/>
2022-09-03 16:08 ` aldyh at gcc dot gnu.org
2022-09-03 17:33 ` law at gcc dot gnu.org [this message]
2023-03-29 17:40 ` aldyh at gcc dot gnu.org
2023-03-29 17:46 ` aldyh at gcc dot gnu.org
2023-03-30 11:50 ` jakub at gcc dot gnu.org
2023-03-30 13:03 ` jakub at gcc dot gnu.org
2023-03-30 13:30 ` jakub at gcc dot gnu.org
2023-03-31 11:43 ` cvs-commit at gcc dot gnu.org

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