gas .macro quirks, and an ARM bug

[Ulf Carlsson]

On Thu, 8 Jun 2000, Nick Clifton wrote:
> : > 2) Cannot pass a string argument with escaped characters to macros.
> : 
> : I agree that this is weird.  The macros don't support expansion of escaped
> : characters in arguments to macros.  Escaped characters are just passed on,
> : with one exception for the quote character itself.  I think the correct
> : behaviour would be to pass '\"' and '\'' on as an escaped character and not
> : treat them as argument delimiters.
> : 
> : 2000-06-07  Ulf Carlsson  <ulfc@engr.sgi.com>
> : 
> : 	* macro.c (getstring): Make it possible to escape the quote character.
> : 
> : Index: macro.c
> : ===================================================================
> : RCS file: /cvs/src/src/gas/macro.c,v
> : retrieving revision 1.7
> : diff -u -p -r1.7 macro.c
> : --- macro.c	2000/05/01 14:01:06	1.7
> : +++ macro.c	2000/06/07 21:49:26
> : @@ -312,6 +312,12 @@ getstring (idx, in, acc)
> :  		  idx++  ;
> :  		  sb_add_char (acc, in->ptr[idx++]);
> :  		}
> : +	      else if (in->ptr[idx] == '\\' && in->ptr[idx+1] == tchar)
> : +		{
> : +		  sb_add_char (acc, '\\');
> : +		  sb_add_char (acc, tchar);
> : +		  idx += 2;
> : +		}
> :  	      else
> :  		{
> :  		  if (in->ptr[idx] == tchar)
> 
> Actually this does not work since it leaves the \ character in the
> input stream rather than stripping it out.  This causes the error
> message:
> 
>   Error: Rest of line ignored. First ignored character is `\'.

No, this was intentional.  The only problem I see with the current
implementation is that you actually can't pass a `\"' through it if you really
want a quote character in your string.

        .macro  hello   narg1
                .asciiz  "\narg1"
        .endm
        hello   "a quote char: \""

This assembles into

	Contents of section .text:
	 0000 61207175 6f746520 63686172 3a202200  a quote char: ".
	Contents of section .data:

You can probably get the same effect by passing `\\"' with your patch, but I
think that's even more obscure since expansion of escape sequences usually
isn't done in arguments to macros.  The logical syntax would have been `\\\"'.

Ulf