From: Robert Lipe <robertl@dgii.com>
To: Ian Lance Taylor <ian@cygnus.com>
Cc: gas2@cygnus.com, law@cygnus.com
Subject: Re: pushl computed immediate address on 2.8.1
Date: Fri, 02 Jan 1998 13:26:00 -0000 [thread overview]
Message-ID: <19980102152547.25804@dgii.com> (raw)
In-Reply-To: <199801022106.QAA01775@subrogation.cygnus.com>
> pushl $.LC0@GOTOFF(%ebx)
> seems to assemble just like
> pushl $LC0
>
> This happens because when gas sees the '$', it passes the rest of the
> line to the expression parsing code. The expression parser doesn't
> recognize the '@', so it just returns .LC0. gas then fails to notice
> that part of the line wasn't parsed.
That sounds like a perfectly reasonable explanation.
> Does this sound right at all? Should GAS error on this?
> It sounds wrong, and I'll change gas to emit an error.
This exercise wasn't entirely academic. EGCS (and presumably GCC)
actually will emit this construct. So, although I agree it is the
right thing to do for the assembler to complain about this, be
prepared that doing so will "break" those tools.
Of course, they never _really_ worked right, but the output would
actually give the desired results in some cases. We'll probably
hear that GAS "broke" the compiler for a while, but in reality, I
think this is a healthy thing and will help expose the real problem
in the x86 part of the compilers.
Thank you, Ian.
RJL
next prev parent reply other threads:[~1998-01-02 13:26 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-01-02 12:41 Robert Lipe
1998-01-02 13:06 ` Ian Lance Taylor
1998-01-02 13:26 ` Robert Lipe [this message]
1998-01-09 20:42 ` H.J. Lu
1998-01-09 23:02 ` Robert Lipe
1998-01-10 14:25 ` H.J. Lu
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