Re: patch to generate align 0 for packed attributes

[Jeffrey A Law <law at cygnus dot com>]

  In message <Pine.SOL.3.91.1000727114220.23599T-100000@emperor.cygnus.com>you 
write:
  > > My first question, I'm guessing that the belief is that the MIPS assemble
  > > is automatically aligning data to their natural boundary?
  > > 
  >   In the example i mentioned, the compiled generates 
  > 
  > 	.byte 1
  > 	.half 2
  > 
  >   In the mips assembler, the .byte directive is aligned to 0 and the
  > .half directive is aligned to 1 generating the above to
  > 
  >    address    value
  >    0000	      01	.byte 1
  >    0001	      00 0200   .half 2
  > 
  > In the assembler, the directives are aligned only if .align is not zero. 
OK.  So, the MIPS assembler does auto-align on .byte/.half, etc directives
and .align 0 turns off auto alignment.  Got it.  Thanks for the code
fragments.

  > > Second, do all MIPS assemblers do this?  If not, then we need to test for
  > > it using autoconf.
To answer my own question, after peeking at the GAS sources and reading its
comments I believe that all MIPS assemblers have this behavior.


  > > Third, you didn't include any documentation on the new target macros.
  > > 
  >   Yes i realized this after i sent out the patch.
But it's not needed with the updated patch.  So I'll withdraw this objection.


  > > Fourth, I would be very leery of this code since it appears to be laying
  > > out bitfields within structures.  If you do it wrong, you'll break ABI
  > > compatibility.
  > 
  >   Yes my patch is wrong as it align's to 0 for every element of a struct. 
  > Here is the revised patch.
  > 
  > Please let me know it is okay to apply.
  > 
  > Thanks
  > Chandra
  > 
  > 
  > 	* varasm.c (output_constructor): Add .align 0 for packed vars.
This is fine.  Please install this patch.

Thanks for your patience and explaining things to me,
jeff