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 9CA873858408; Tue, 23 Jan 2024 12:32:31 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 9CA873858408
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1706013151;
	bh=3uKpSHJ6HmqjNXYLGPEGlgM6eHCXqUNrGcXM15dhYVI=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=WksP2s/cLSZvLxd+uUOsW13dK4CFuEUZQC199aPUjqxyWvJ2Uvb7jjpfRJxPzyJwr
	 R11tF60tx/i5hgvFjf8RHoMS9kulUyKzlU39rk1NhgT6AfYwfHko14wAzbYKZ74oYe
	 tVDcTbVX77AwDtAL9n0UYtTCPU5HxverUDWDBjqw=
From: "tnfchris at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/113441] [14 Regression] Fail to fold the last
 element with multiple loop
Date: Tue, 23 Jan 2024 12:32:31 +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: missed-optimization, needs-bisection
X-Bugzilla-Severity: normal
X-Bugzilla-Who: tnfchris at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
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-113441-4-1Gb3LOEQzg@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-113441-4@http.gcc.gnu.org/bugzilla/>
References: <bug-113441-4@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=3D113441

--- Comment #17 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
Ok, bisected to

g:2efe3a7de0107618397264017fb045f237764cc7 is the first bad commit
commit 2efe3a7de0107618397264017fb045f237764cc7
Author: Hao Liu <hliu@os.amperecomputing.com>
Date:   Wed Dec 6 14:52:19 2023 +0800

    tree-optimization/112774: extend the SCEV CHREC tree with a nonwrapping
flag

Before this commit we were unable to analyse the stride of the access.
After this niters seems to estimate the loop trip count at 4 and after that=
 the
logs diverge enormously.=