From: Jan Beulich <jbeulich@suse.com>
To: Binutils <binutils@sourceware.org>
Cc: "H.J. Lu" <hjl.tools@gmail.com>
Subject: [PATCH] x86: simplify and slightly correct XCHG vs NOP checking
Date: Thu, 1 Dec 2022 10:11:50 +0100 [thread overview]
Message-ID: <35539292-53a8-292d-2f5d-f65ad02a36bb@suse.com> (raw)
For one, because of CheckRegSize, there's no need to check the size of
both (register) operands. And then in process_suffix() check opcode
space rather than the (potentially ambiguous) extension opcode.
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -6686,8 +6686,7 @@ match_template (char mnem_suffix)
&& t->opcode_modifier.opcodespace == SPACE_BASE
&& i.types[0].bitfield.instance == Accum
&& i.types[0].bitfield.dword
- && i.types[1].bitfield.instance == Accum
- && i.types[1].bitfield.dword)
+ && i.types[1].bitfield.instance == Accum)
continue;
/* xrelease mov %eax, <disp> is another special case. It must not
match the accumulator-only encoding of mov. */
@@ -7408,11 +7407,10 @@ process_suffix (void)
need rex64. */
&& ! (i.operands == 2
&& i.tm.base_opcode == 0x90
- && i.tm.extension_opcode == None
+ && i.tm.opcode_modifier.opcodespace == SPACE_BASE
&& i.types[0].bitfield.instance == Accum
&& i.types[0].bitfield.qword
- && i.types[1].bitfield.instance == Accum
- && i.types[1].bitfield.qword))
+ && i.types[1].bitfield.instance == Accum))
i.rex |= REX_W;
break;
next reply other threads:[~2022-12-01 9:12 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-01 9:11 Jan Beulich [this message]
2022-12-01 16:43 ` H.J. Lu
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=35539292-53a8-292d-2f5d-f65ad02a36bb@suse.com \
--to=jbeulich@suse.com \
--cc=binutils@sourceware.org \
--cc=hjl.tools@gmail.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).