From: Chad <chad.page@gmail.com>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] Performance bug in tcg/i386 output:
Date: Sun, 8 Nov 2009 09:47:30 -0800 [thread overview]
Message-ID: <f784f5260911080947s732fa25bj1251778a7d91447f@mail.gmail.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 417 bytes --]
Running qemu[-i386] with -d out_asm and looking at qemu.out shows this
test/j**/jmp pattern repeatedly:
0xb1aa40f6: test %ecx,%ecx
0xb1aa40f8: jne 0xb1aa4115
0xb1aa40fe: jmp 0xb1aa4103
0xb1aa4103: mov $0xc0bf,%eax
Therefore there's a bug in the tcg generator creating many unnecessary
jmps. It might get optimized out by the CPU, but it might not and it bloats
the asm output in any case...
- Chad
[-- Attachment #2: Type: text/html, Size: 455 bytes --]
next reply other threads:[~2009-11-08 17:47 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-08 17:47 Chad [this message]
2009-11-08 17:56 ` [Qemu-devel] Performance bug in tcg/i386 output: Laurent Desnogues
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=f784f5260911080947s732fa25bj1251778a7d91447f@mail.gmail.com \
--to=chad.page@gmail.com \
--cc=qemu-devel@nongnu.org \
/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 NNTP newsgroup(s).