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Re: Override arm-elf-as comment char


> There seems to be a conflict in the arm-elf-as syntax. gas/config/tc-arm.c
> has '@' listed as a comment character. Unfortunately gas/config/obj-elf.c
> requires the use of '@' in order to specify @nobits or @progbits options to
> the .section pseudo-op.
> 
> I've pored over gas/app.c, but can't find any way to escape the '@' so it
> gets passed through.
> 
> This should be fixed, otherwise it's impossible to mark sections as
> equivalent to the BSS. But what should give? Presumably '@' is a comment
> character for compatibility with the ARM SDT? So should we instead change
> app.c to allow the escape any character?
> 

When I originally ported gas to the ARM it was designed to be 
substantially compatible with the assembler for RISC iX (Acorn's Unix 
port).  This used @ as the assembler comment character (it had other 
wierdnesses too, such as the way .align was implemented).  This was the 
format that gcc was generating for a.out targets.  Of course, since then a 
large amount of assembler has been written that assumes that @ is the 
comment char, so I doubt it would be feasible to change it now, even for 
just elf ports.

I've seen other similar problems in the past; netbsd has a .type directive 
which normally expects @<function-name> as an argument; the solution 
adopted was to use a different character in .type rather than try to hack 
the assembler not to introduce a comment for some uses of @.

ARM SDT compatibility is not an issue.  The syntax used by the SDT 
assembler is, unfortunately, completely different from that used in gas 
and not very compatible with the way gas is designed.

Richard


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