From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id 7510E3857B8B; Tue,  8 Nov 2022 15:34:03 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 7510E3857B8B
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1667921643;
	bh=MIj0qkw0az8RL6ju+U4Y3wFmj02aATMQdRhUdOYbOAc=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=Ra94xT/D9YbiNjzsii0yDcHxbeDXzNyc45dkqIlNsRxPGw9QfQJcxGwzKORdCUfBo
	 xSwXXuwqko6xrY8z0pBBGNUFTTyt4Z3gElZhpH30aXiNzlzY4qOgW/+up/sJ07M/R5
	 VuStUuw7UWFTHvHnuduYVbFsG5BPTWlo6/Wdq+FQ=
From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/107569] [13 Regression] Failure to optimize
 std::isfinite since r13-3596
Date: Tue, 08 Nov 2022 15:34:02 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 13.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jakub at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P1
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 13.0
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-107569-4-eZT1cFuyLX@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-107569-4@http.gcc.gnu.org/bugzilla/>
References: <bug-107569-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107569

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
__builtin_isfinite (x) is implemented as
~UNGT_EXPR<ABS_EXPR<x>, DBL_MAX>.
So, if we have:
  _3 =3D ABS_EXPR <x_2(D)>;
  _4 =3D _3 u> 1.79769313486231570814527423731704356798070567525844996599e+=
308;
  _5 =3D ~_4;
  return _5;
for assume function, we should start with [1,1] assumption on _5, that impl=
ies
_4 [0,0], and from UNGT_EXPR being false, we should derive that
_3 is [-inf, 1.79769313486231570814527423731704356798070567525844996599e+30=
8]
and not NaN (if any operand is NaN, UNGT_EXPR is true, it stands for unorde=
red
or greater).
And from _3 being [-inf,
1.79769313486231570814527423731704356798070567525844996599e+308] not NaN
we should derive that x_2(D) is
[-1.79769313486231570814527423731704356798070567525844996599e+308,
1.79769313486231570814527423731704356798070567525844996599e+308] not NaN
(aka finite number).=