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 08D27385828D; Tue, 12 Jul 2022 07:52:13 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 08D27385828D
From: "andrew at sifive dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/106265] RISC-V SPEC2017 507.cactu code bloat due to
 address generation
Date: Tue, 12 Jul 2022 07:52:13 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 12.1.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: andrew at sifive dot com
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: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-106265-4-ccGsT1ZFLz@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-106265-4@http.gcc.gnu.org/bugzilla/>
References: <bug-106265-4@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
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Tue, 12 Jul 2022 07:52:14 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106265

--- Comment #6 from Andrew Waterman <andrew at sifive dot com> ---
To be clear, `li rx, 4096' isn't unsupported: it's a
very-much-supported idiom for `lui rx, 1`.


On Mon, Jul 11, 2022 at 11:45 PM rguenth at gcc dot gnu.org via
Gcc-bugs <gcc-bugs@gcc.gnu.org> wrote:
>
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106265
>
> --- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
> So why do we even emit unsupported 'li 4096' and leave it to the linker to
> "optimize(?)"?  At least the cost of this should be reflected - IIRC powe=
rpc
> recently got improvements for similar cases by changing the targets rtx_c=
ost
> hook to properly const SET from CONST_INT so that CSE doesn't leave so ma=
ny
> sets from constants around.
>
> OTOH LRA rematerialization also could be the culprit, thinking rematerial=
izing
> the constant is cheaper than spilling a register holding it.=