From: Tom de Vries <vries@codesourcery.com>
To: gcc-patches@gcc.gnu.org, ebotcazou@libertysurf.fr
Cc: Maxim Kuvyrkov <maxim@codesourcery.com>,
Bernd Schmidt <bernds@codesourcery.com>
Subject: [PATCH, PR43920, 4-9/9] Cross-jumping.
Date: Thu, 31 Mar 2011 18:35:00 -0000 [thread overview]
Message-ID: <4D94C88B.4020206@codesourcery.com> (raw)
In-Reply-To: <4D94C603.7080505@codesourcery.com>
The impact of patches 4-9 of the patch set on the example from the bug
report for ARM Thumb-2 -Os is a further size reduction of 7%, from 58 to
54 bytes.
This size reduction is illustrated in this diff of the assembly
(left, without patches, size 58. right, with patches, size 54):
...
push {r3, r4, r5, r6, r7, push {r3, r4, r5, r6, r7,
mov r7, r1 mov r7, r1
mov r6, r2 mov r6, r2
movs r1, #0 movs r1, #0
movs r2, #1 movs r2, #1
mov r5, r0 mov r5, r0
bl lseek bl lseek
movs r1, #0 movs r1, #0
movs r2, #2 movs r2, #2
mov r4, r0 mov r4, r0
mov r0, r5 mov r0, r5
bl lseek bl lseek
adds r2, r4, #1 adds r2, r4, #1
beq .L3 | beq .L5
adds r3, r0, #1 adds r3, r0, #1
beq .L2 beq .L2
subs r0, r0, r4 subs r0, r0, r4
beq .L5 beq .L5
str r4, [r7, #0] str r4, [r7, #0]
str r0, [r6, #0] str r0, [r6, #0]
movs r0, #0 movs r0, #0
pop {r3, r4, r5, r6, r7, pop {r3, r4, r5, r6, r7,
.L3: <
mov r0, r4 <
pop {r3, r4, r5, r6, r7, <
.L5: .L5:
mov r0, #-1 mov r0, #-1
.L2: .L2:
pop {r3, r4, r5, r6, r7, pop {r3, r4, r5, r6, r7,
...
The patches 4-9 allows crossjumping:
- to recognize that 'mov r0, r4' and 'move r0, #-1' have the same
effect, and
- to extend the search scope past label .L2 backward to .L5, in order
to recognize that the jump to .L3 can be replaced with a jump to .L5.
Thanks,
- Tom
next prev parent reply other threads:[~2011-03-31 18:31 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-31 18:27 [PATCH, PR43920] Improve code-size optimizations Tom de Vries
2011-03-31 18:29 ` [PATCH, PR43920, 1/9] ARM specific part Tom de Vries
2011-04-01 14:46 ` Tom de Vries
2011-04-01 15:19 ` Richard Earnshaw
2011-04-01 16:06 ` Tom de Vries
2011-04-02 7:47 ` Richard Guenther
2011-04-02 17:06 ` Tom de Vries
2011-04-03 7:38 ` Richard Guenther
2011-04-03 17:03 ` Tom de Vries
[not found] ` <BANLkTikEruAfGJ392FXtasLv6-yV2tYSRQ@mail.gmail.com>
2011-04-04 12:14 ` Richard Guenther
2011-04-04 12:23 ` Rainer Orth
2011-04-05 13:35 ` Tom de Vries
2011-05-03 18:19 ` Rainer Orth
2011-04-03 18:40 ` Mike Stump
2011-03-31 18:31 ` [PATCH, PR43920, 2/9] ARM specific part - test case Tom de Vries
2011-04-01 14:47 ` Tom de Vries
2011-04-01 15:17 ` Tom de Vries
2011-04-01 15:34 ` Richard Earnshaw
2011-04-01 16:10 ` Tom de Vries
2011-04-05 10:43 ` Tom de Vries
2011-04-05 12:20 ` Richard Earnshaw
2011-04-06 10:48 ` Ramana Radhakrishnan
2011-04-06 12:29 ` Tom de Vries
2011-03-31 18:35 ` [PATCH, PR43920, 3/9] Cleanup Tom de Vries
2011-03-31 18:43 ` Jeff Law
2011-04-01 14:48 ` Tom de Vries
2011-04-01 15:15 ` Tom de Vries
2011-04-04 18:26 ` Jeff Law
2011-03-31 18:35 ` Tom de Vries [this message]
2011-03-31 18:36 ` [PATCH, PR43920, 4/9] Cross-jumping - Don't count use or clobber Tom de Vries
2011-03-31 18:40 ` Jeff Law
2011-03-31 19:09 ` Tom de Vries
2011-03-31 19:19 ` Jeff Law
2011-04-01 14:48 ` Tom de Vries
2011-04-04 19:11 ` Jeff Law
2011-03-31 18:42 ` [PATCH, PR43920, 5/9] Cross-jumping - Add missing use of return register Tom de Vries
2011-03-31 18:52 ` Jeff Law
2011-04-01 14:49 ` Tom de Vries
2011-04-04 19:11 ` Jeff Law
2011-03-31 18:44 ` [PATCH, PR43920, 6/9] Cross-jumping - Use reg-notes Tom de Vries
2011-03-31 18:56 ` Jeff Law
2011-03-31 21:25 ` Tom de Vries
2011-04-01 14:54 ` Tom de Vries
2011-04-04 16:14 ` Tom de Vries
2011-04-06 17:41 ` Jeff Law
2011-03-31 18:45 ` [PATCH, PR43920, 7/9] Cross-jumping - Extend search scope Tom de Vries
2011-03-31 18:58 ` Jeff Law
2011-04-05 11:44 ` Tom de Vries
2011-04-01 14:55 ` Tom de Vries
2011-04-05 21:45 ` Jeff Law
2011-03-31 18:46 ` [PATCH, PR43920, 8/9] Cross-jumping - Extend search scope - test case Tom de Vries
2011-03-31 19:00 ` Jeff Law
2011-04-01 14:56 ` Tom de Vries
2011-04-01 15:01 ` Jakub Jelinek
2011-04-01 15:18 ` Tom de Vries
2011-04-01 16:14 ` Tom de Vries
2011-04-05 21:46 ` Jeff Law
2011-03-31 18:56 ` [PATCH, PR43920, 9/9] Cross-jumping - Allow both directions Tom de Vries
2011-03-31 19:02 ` Jeff Law
2011-04-01 14:56 ` Tom de Vries
2011-04-05 21:46 ` Jeff Law
2011-03-31 21:16 ` [PATCH, PR43920] Improve code-size optimizations Eric Botcazou
2011-04-01 15:06 ` Tom de Vries
2011-04-01 16:06 ` Eric Botcazou
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4D94C88B.4020206@codesourcery.com \
--to=vries@codesourcery.com \
--cc=bernds@codesourcery.com \
--cc=ebotcazou@libertysurf.fr \
--cc=gcc-patches@gcc.gnu.org \
--cc=maxim@codesourcery.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).