gas: parsing source lines containing macro args

[Andrew Haley <aph at pasanda dot cygnus dot co dot uk>]

Consider a source file that looks like this:

-----------------------------------------------------------------------
        .macro  foo_macro arg0, arg1
        foo \arg0,\arg1,0
        .endm

        .vu
n1:     foo_macro %r01,%r00
n2:	foo %r01,%r00,0
-----------------------------------------------------------------------

Line n1 expands to "foo %r01,%r00,0", which is the same as line n2.

However, if there is another token on the line inside the macro, bad
things happen:

-----------------------------------------------------------------------
        .macro  foo_macro arg0, arg1
        bar foo \arg0,\arg1,0
        .endm

        .vu
n1:     foo_macro %r01,%r00
n2:	bar foo %r01,%r00,0
-----------------------------------------------------------------------

Instead of being expanded to "bar foo %r01,%r00,0", line n1 is
expanded to "bar foo%r01,%r00,0": a space has disappeared.  This
happens becase when gas is scanning Line n1, any spaces after the
second operand are ignored *unless* they occur immediately before an
operand character.  Unfortunately, in this case the space in question
is immediately before a backslash, which is not an operand character,
so the space is dropped.

My patch fixes this by outputting a space when going from State 10
(after seeing whitespace in state 9) to State 3 (after second white on
line) iff the non-whitepsace character which caused the transition was
a backslash.

I thin that this genuinely is a special case, because a backslash
should only be treated as an operand char when the backslash appears
as the first character of an operand.

Andrew.


1999-11-08  Andrew Haley  <aph@cygnus.com>

	* app.c (do_scrub_chars): When in State 10, treat backslash
	characters in the same way as as symbol characters.

Index: app.c
===================================================================
RCS file: /cvs/binutils/binutils/gas/app.c,v
retrieving revision 1.3
diff -p -r1.3 app.c
*** app.c	1999/07/11 20:19:53	1.3
--- app.c	1999/11/08 16:48:03
*************** do_scrub_chars (get, tostart, tolen)
*** 1227,1232 ****
--- 1227,1242 ----
  	    }
  	  else if (state == 10)
  	    {
+ 	      if (ch == '\\')
+ 		{
+ 		  /* Special handling for backslash: a backslash may
+ 		     be the beginning of a formal parameter (of a
+ 		     macro) following another symbol character, with
+ 		     whitespace in between.  We skipped the whitespace
+ 		     earlier, so output it now.  */
+ 		  PUT (' ');
+ 		}
+ 
  	      state = 3;
  	    }
  	  PUT (ch);