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 1D5793858025; Thu,  4 Jan 2024 16:35:17 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 1D5793858025
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1704386118;
	bh=XOd4uac1ptKIrET2jTpdnGrfSaZpeQN7WGQtTVKHozo=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=mDtHmBBpQRp9nd6pwRJTRMX5ecgbTvYNz/Y4Z0vLJ+2ghskOHzJ4uvTBAc/md70Jb
	 fuVdx+1oMYVruTXw8X46V3cnW0VZvQa19iVlSkmUUA0cXY2xHdsVVzfV29HSGNOCdp
	 +gZNkyNKMWnL4sjQvP/g0Ei6D2XT69fHcmesWkO0=
From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/110852] [14 Regression] ICE: in
 get_predictor_value, at predict.cc:2695 with -O -fno-tree-fre and
 __builtin_expect() since r14-2219-geab57b825bcc35
Date: Thu, 04 Jan 2024 16:35:08 +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: 14.0
X-Bugzilla-Keywords: ice-on-valid-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jakub at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P1
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 14.0
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-110852-4-AOCEarHikV@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-110852-4@http.gcc.gnu.org/bugzilla/>
References: <bug-110852-4@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=3D110852

--- Comment #12 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Jan Hubicka from comment #11)
> I added the early exits to handle the following case.
>=20
> a =3D b * c
>=20
> If b is prediced to 0 with predictor1, while c is predicted to 1 with
> predictor2 your version will predict a to be 0, but will merge
> predictor1 and 2 leading to lower probability than predictor1 alone.
> So the early exit will give bit higher chance for not losing
> information.

I thought the goal was to handle what is in predict-18.c, i.e.
b * __builtin_expect (c, 0)
or similar.  If it is about
__builtin_expect_with_probability (b, 42, 0.25) *
__builtin_expect_with_probability (c, 0, 0.42)
sure, my version will merge the probabilities, while you'll pick the
probability from
the 0 case.=