From: "Jan Beulich" <JBeulich@suse.com>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: <binutils@sourceware.org>
Subject: Re: [committed, PATCH] PR binutis/18386: callw with 0x66 prefix incorrectly disassembled in 64-bit mode
Date: Mon, 11 May 2015 07:28:00 -0000 [thread overview]
Message-ID: <555076520200007800078B8F@mail.emea.novell.com> (raw)
In-Reply-To: <20150509135213.GA720@gmail.com>
>>> On 09.05.15 at 15:52, <hjl.tools@gmail.com> wrote:
> The operand size prefix (0x66) is ignored for 32-bit PC-relative call,
> jmp and jcc in 64-bit mode.
Now that's again a change that should have been discussed
before committing: While it is correct for the Intel implementation
of x86-64, it isn't for AMD's original (and I'd tend to say that the
latter is more correct, since afaik there's nowhere that exceptions
are being made for the meaning of the operand size prefix).
Apart from that I find it odd that you mention only 32-bit PC-relative
branches when the same behavioral difference also applies to 8-bit
displacement ones as well as near branches to absolute addresses
(including returns). And of course there are more differences
elsewhere. Perhaps this should be hidden behind an option to
select the flavor, defaulting (imo) to the original AMD behavior.
Jan
next prev parent reply other threads:[~2015-05-11 7:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-09 13:52 H.J. Lu
2015-05-11 7:28 ` Jan Beulich [this message]
2015-05-11 11:04 ` H.J. Lu
2015-05-11 11:29 ` Jan Beulich
2015-05-11 12:40 ` H.J. Lu
2015-05-11 13:22 ` Jan Beulich
2015-05-11 13:33 ` H.J. Lu
2015-05-12 9:42 ` Jan Beulich
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