Patch: Allow xstormy16-elf-gas to handle "@fptr() - @fptr()"

[Nick Clifton <nickc at redhat dot com>]

Hi Guys,

  xstormy-elf-gcc can generate an assembler expression that is the
  difference of two function pointers that looks like this:

    .howrd @fptr(foo) - @fptr(bar).

  xstormy-elf-gas however cannot handle this expression and produces a
  very strange error message (about an unrecognised case value in a
  symbol).

  The patch below adds the ability to handle this kind of expression
  to xstormy-elf-gas.

Cheers
        Nick

2003-05-12  Nick Clifton  <nickc@redhat.com>

	* config/tc-xstormy16.c (skipping_fptr): New local variable.
	(md_assemble): Reset skipping_fptr.
	(md_operand): If @fptr() is followed by a minus sign, set
	skipping_fptr and ignore the fptr.  If skipping_fptr is set and an
	@fptr is detected, ignore it and reset skipping_fptr.

Index: gas/config/tc-xstormy16.c
===================================================================
RCS file: /cvs/src/src/gas/config/tc-xstormy16.c,v
retrieving revision 1.10
diff -c -3 -p -w -r1.10 tc-xstormy16.c
*** gas/config/tc-xstormy16.c	2 May 2003 12:42:13 -0000	1.10
--- gas/config/tc-xstormy16.c	12 May 2003 09:05:33 -0000
*************** md_begin ()
*** 104,109 ****
--- 104,111 ----
    cgen_set_parse_operand_fn (gas_cgen_cpu_desc, gas_cgen_parse_operand);
  }
  
+ static bfd_boolean skipping_fptr = FALSE;
+ 
  void
  md_assemble (str)
       char * str;
*************** md_assemble (str)
*** 111,116 ****
--- 113,122 ----
    xstormy16_insn insn;
    char *    errmsg;
  
+   /* Make sure that if we had an erroneous input line which triggered
+      the skipping_fptr boolean that it does not affect following lines.  */
+   skipping_fptr = FALSE;
+ 
    /* Initialize GAS's cgen interface for a new instruction.  */
    gas_cgen_init_parse ();
  
*************** md_operand (e)
*** 154,162 ****
--- 160,187 ----
  	  goto err;
  	}
        input_line_pointer++;
+       SKIP_WHITESPACE ();
  
        if (e->X_op != O_symbol)
  	as_bad ("Not a symbolic expression");
+       else if (* input_line_pointer == '-')
+ 	/* We are computing the difference of two function pointers
+ 	   like this:
+ 
+ 	    .hword  @fptr (foo) - @fptr (bar)
+ 
+ 	  In this situation we do not want to generate O_fptr_symbol
+ 	  operands because the result is an absolute value, not a
+ 	  function pointer.
+ 
+ 	  We need to make the check here, rather than when the fixup
+ 	  is generated as the function names (foo & bar in the above
+ 	  example) might be local symbols and we want the expression
+ 	  to be evaluated now.  This kind of thing can happen when
+ 	  gcc is generating computed gotos.  */
+ 	skipping_fptr = TRUE;
+       else if (skipping_fptr)
+ 	skipping_fptr = FALSE;
        else
          e->X_op = O_fptr_symbol;
      }