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Re: gas:Reject ++ and --
- From: Jakub Jelinek <jakub at redhat dot com>
- To: Nathan Sidwell <nathan at codesourcery dot com>
- Cc: Alan Modra <amodra at bigpond dot net dot au>, binutils at sources dot redhat dot com, Michal Ostrowski <mostrows at watson dot ibm dot com>
- Date: Tue, 18 May 2004 21:35:27 +0200
- Subject: Re: gas:Reject ++ and --
- References: <40587B89.5050107@codesourcery.com> <20040416015426.GA2557@bubble.modra.org> <407FFBB1.4000804@codesourcery.com>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
On Fri, Apr 16, 2004 at 04:28:49PM +0100, Nathan Sidwell wrote:
> Alan Modra wrote:
> >On Wed, Mar 17, 2004 at 04:23:37PM +0000, Nathan Sidwell wrote:
> >
> >>the attached patch causes gas to not interpret ++ and -- as two
> >>+ or - operators in a row. The current behaviour is to allow
> >>'a ++ b' as if it was 'a + (+b)' and '++ a' as if '+(+a)'. The problem
> >
> >
> >This patch had an off-by-one error, breaking code like the following:
> Gah!, sorry
Even with this fix the ++/-- patch breaks previously working code.
E.g. Linux kernel contains:
#define MOVE_SHORTCHUNK(src, dst, offset, t0, t1) \
ldub [%src - offset - 0x02], %t0; \
ldub [%src - offset - 0x01], %t1; \
stb %t0, [%dst - offset - 0x02]; \
stb %t1, [%dst - offset - 0x01];
...
MOVE_SHORTCHUNK(o1, o0, -0x02, g2, g3)
MOVE_SHORTCHUNK(o1, o0, -0x04, g2, g3)
MOVE_SHORTCHUNK(o1, o0, -0x06, g2, g3)
MOVE_SHORTCHUNK(o1, o0, -0x08, g2, g3)
MOVE_SHORTCHUNK(o1, o0, -0x0a, g2, g3)
MOVE_SHORTCHUNK(o1, o0, -0x0c, g2, g3)
MOVE_SHORTCHUNK(o1, o0, -0x0e, g2, g3)
MOVE_SHORTCHUNK(o1, o0, -0x10, g2, g3)
...
MOVE_SHORTCHUNK(o1, o0, 0x0c, g2, g3)
MOVE_SHORTCHUNK(o1, o0, 0x0a, g2, g3)
MOVE_SHORTCHUNK(o1, o0, 0x08, g2, g3)
MOVE_SHORTCHUNK(o1, o0, 0x06, g2, g3)
MOVE_SHORTCHUNK(o1, o0, 0x04, g2, g3)
MOVE_SHORTCHUNK(o1, o0, 0x02, g2, g3)
MOVE_SHORTCHUNK(o1, o0, 0x00, g2, g3)
...
Note there wasn't ++ nor -- present in the assembly, but
ldub [%o1 - -0x02 - 0x02], %g2
Yet current CVS gas still refuses it.
Jakub