From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugs-return-461292-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org>
Received: (qmail 10085 invoked by alias); 5 Sep 2014 12:41:35 -0000
Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm
Precedence: bulk
List-Id: <gcc-bugs.gcc.gnu.org>
List-Archive: <http://gcc.gnu.org/ml/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-help@gcc.gnu.org>
Sender: gcc-bugs-owner@gcc.gnu.org
Received: (qmail 10004 invoked by uid 48); 5 Sep 2014 12:41:26 -0000
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/55334] [4.8/4.9/5 Regression] mgrid regression (ipa-cp disables vectorization)
Date: Fri, 05 Sep 2014 12:41:00 -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: 4.8.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenth at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Priority: P2
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 4.9.2
X-Bugzilla-Flags:
X-Bugzilla-Changed-Fields:
Message-ID: <bug-55334-4-CgVjpGLMM4@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-55334-4@http.gcc.gnu.org/bugzilla/>
References: <bug-55334-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-SW-Source: 2014-09/txt/msg01126.txt.bz2

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55334

--- Comment #42 from Richard Biener <rguenth at gcc dot gnu.org> ---
With the proposed patch (with a tiny fix) I get:

(compute_affine_dependence
  stmt_a: _23 = MEM[(real(kind=8)[0:D.2444] *)&x clique 1 base 4][_20];
  stmt_b: _112 = MEM[(real(kind=8)[0:D.2444] *)&x clique 1 base 4][_111];
(analyze_overlapping_iterations
  (chrec_a = {pretmp_822 + 2, +, 1}_6)
  (chrec_b = {pretmp_850 + 1, +, 1}_6)
(analyze_siv_subscript
  siv test failed: unimplemented)
  (overlap_iterations_a = not known)
  (overlap_iterations_b = not known))
) -> dependence analysis failed

but the cases like the following work

(compute_affine_dependence
  stmt_a: _23 = MEM[(real(kind=8)[0:D.2444] *)&x clique 1 base 4][_20];
  stmt_b: _110 = MEM[(real(kind=8)[4] *)&x + 58071104B clique 1 base 3][3];
) -> no dependence

and finally

mgrid.f:191:0: note: LOOP VECTORIZED

mgrid.f:184:0: note: vectorized 1 loops in function.

and speed is back!

unpatched:

> /usr/bin/time ./a.out < mgrid.in > /dev/null
66.72user 0.05system 1:06.76elapsed 100%CPU (0avgtext+0avgdata
57804maxresident)k
0inputs+8360outputs (0major+14505minor)pagefaults 0swaps

patched:

> /usr/bin/time ./a.out < mgrid.in > /dev/null
61.90user 0.13system 1:02.16elapsed 99%CPU (0avgtext+0avgdata
57804maxresident)k
1472inputs+0outputs (9major+14496minor)pagefaults 0swaps

not sure if that is full recovery (but it's 10% and thus noticable).

I'll post the updated patch which still lacks the correctness part in the
inliner.