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 6766F3858C1F; Wed, 22 Mar 2023 09:11:29 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6766F3858C1F
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1679476289;
	bh=XNvNn1RmGVQOkI6GGvbW+sbxWGw6n+z90MjZy4KHTCg=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=CDaBQpQwpFcgZ/2+uNNrbABLBty5pgwby9uRfL/Uk/w3FKVCd7wc8+ZHp9Bng8VxF
	 deqWtfzgnVk3TBqmtT1R9vnFrRwWkGUVP80qsD4vhez4pAUJGqkkJjEo0KfK4dLBXU
	 uv1BzgbcbbyEK7U+gJDPQ8EasSMfBVIXmsSW4174=
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug debug/109237] csmith: another timeout with -g -O3 this time
 since r12-156-g8d4c374c4419a875
Date: Wed, 22 Mar 2023 09:11:27 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: debug
X-Bugzilla-Version: 13.0
X-Bugzilla-Keywords: compile-time-hog, needs-reduction
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenth at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-109237-4-XfEepCNCoJ@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-109237-4@http.gcc.gnu.org/bugzilla/>
References: <bug-109237-4@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=3D109237

--- Comment #9 from Richard Biener <rguenth at gcc dot gnu.org> ---
Samples: 289K of event 'cycles:u', Event count (approx.): 384226334976=20=
=20=20=20=20=20=20=20=20=20
Overhead       Samples  Command  Shared Object     Symbol=20=20=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20=20
   3.52%          9747  cc1      cc1               [.] bb_is_just_return=20=
=20=20=20=20=20=20
           #
   2.94%          8241  cc1      cc1               [.] df_note_compute=20=
=20=20=20=20=20=20=20=20
           #
   2.92%          8085  cc1      cc1               [.] init_alias_analysis=
=20=20=20=20=20
           #
   2.55%          7035  cc1      cc1               [.]
delete_trivially_dead_insns         #
   2.28%          6372  cc1      cc1               [.]
contains_no_active_insn_p           #
   2.16%          6288  cc1      cc1               [.] get_ref_base_and_ext=
ent=20
           #
   2.02%          5785  cc1      cc1               [.] ggc_set_mark=20=20=
=20=20=20=20=20=20=20=20=20=20
           #
   1.55%          4308  cc1      cc1               [.] fast_dce=20=20=20=20=
=20=20=20=20=20=20=20=20=20=20=20=20
           #

I see that bb_is_just_return is high in the profile and looking at its
implementation I wonder whether on RTL we can scan insns backwards and
stop if the last (real?) insn isn't ANY_RETURN_P ()?  Using
FOR_BB_INSNS_REVERSE puts it off the profile completely.  Will test a patch.

Similar contains_no_active_insn_p is high up in the profile and it looks
like micro-optimizing it a bit would help.  Using NONDEBUG_INSN_P to
guard the flow_active_insn_p call doesn't seem to help (but perf is always
noisy).=