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 C002F3858D32; Sun,  5 Mar 2023 12:19:04 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org C002F3858D32
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1678018744;
	bh=ePlKs+9ltgMPBA4MQ8AjaYYwMz5TklNr4KnZIgCFJRg=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=t2HEEx5InC1Mjp6LM3BTq2bfRS6TBBu8nAOR6IO11iveuqtr8kScV7m8h5mhAB+wp
	 U0Amdo60Jp4V5O6XGGs2p0qwrUvXw2qkscBi/6HZJonrB2EzynZ0quNDB6OMFYHcn7
	 jmH9VXHY6T+EJl01Czwufh4JQyG7bdm/SSR++hn0=
From: "jskumari at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/109009] Shrink Wrap missed opportunity
Date: Sun, 05 Mar 2023 12:19:04 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: rtl-optimization
X-Bugzilla-Version: unknown
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jskumari at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: jskumari at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-109009-4-NYRbg9NsxY@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-109009-4@http.gcc.gnu.org/bugzilla/>
References: <bug-109009-4@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=3D109009

--- Comment #3 from Surya Kumari Jangala <jskumari at gcc dot gnu.org> ---
For the working case:

 * Input RTL to the IRA pass:
BB2:
  set r123, r4
  set r122, r3
  set r120, compare(r123, 0)
  set r118, r122
  if r120 jump BB4 else jump BB3
BB3:
  call bar()
BB4:
  set r3, r118
  return


 * RTL after the IRA pass:
same as the input

 * RTL after reload pass:
BB2:
  set r100, compare(r4, 0)
  if r100 jump BB4 else jump BB3
BB3:
  set mem(r1+32), r3
  call bar()
  set r3, mem(r1+32)

-----------

For the failing case:

 * Input RTL to the IRA pass:
BB2:
  set r123, r4
  set r122, r3
  set r120, compare(r123, 0)
  set r118, r122
  if r120 jump BB4 else jump BB3
BB3:
  call bar()
BB4:
  set r3, r118+1
  return r3

  * RTL after IRA pass
same as the input

  * RTL after reload pass
BB2:
  set r100, compare(r4, 0)
  set r31, r3
  if r100 jump BB4 else jump BB3
BB3:
  call bar()
BB4:
  set r3, r31+1
  return r3

--------

After the IRA pass, the IR looks very similar in both the working and faili=
ng
testcases. But the reload pass produces different IR.=20
The live ranges seem to be properly split after IRA. I will be checking why=
 the
reload/LRA pass produces different IR.=