Re: [RFC] More compact (100x) -g3 .debug_macinfo (take 2)

[Richard Henderson <rth@redhat.com>]

On 07/15/2011 08:42 AM, Jakub Jelinek wrote:

> The newly added opcodes:
> DW_MACINFO_GNU_define_indirect		0xe0
> 	This opcode has two arguments, one is uleb128 lineno and the
> 	other is offset size long byte offset into .debug_str.  Except
> 	for the encoding of the string it is similar to DW_MACINFO_define.
> DW_MACINFO_GNU_undef_indirect		0xe1
> 	This opcode has two arguments, one is uleb128 lineno and the
> 	other is offset size long byte offset into .debug_str.  Except
> 	for the encoding of the string it is similar to DW_MACINFO_undef.
> DW_MACINFO_GNU_transparent_include	0xe2
> 	This opcode has a single argument, a offset size long byte offset into
> 	.debug_macinfo.  It instructs the debug info consumer that
> 	this opcode during reading should be replaced with the sequence
> 	of .debug_macinfo opcodes from the mentioned offset, up to
> 	a terminating 0 opcode (not including that 0).
> DW_MACINFO_GNU_define_opcode		0xe3
> 	This is an opcode for future extensibility through which
> 	a debugger could skip unknown opcodes.  It has 3 arguments:
> 	1 byte opcode number, uleb128 count of arguments and
> 	a count bytes long array, with a DW_FORM_* code how the
> 	argument is encoded.

I do like the new opcodes.

Elsewhere you described transparent_include as also saving state
about defined opcodes around the include.  Do you want to either
describe that or drop it?



> +	case DW_MACINFO_define:
> +	case DW_MACINFO_undef:
> +#ifdef OBJECT_FORMAT_ELF
> +	  if (!dwarf_strict
> +	      && HAVE_COMDAT_GROUP
> +	      && VEC_length (macinfo_entry, files) != 1
> +	      && i > 0
> +	      && i + 1 < length
> +	      && VEC_index (macinfo_entry, macinfo_table, i - 1)->code == 0)
> +	    {
> +	      char linebuf[sizeof (HOST_WIDE_INT) * 3 + 1];
> +	      unsigned char checksum[16];
> +	      struct md5_ctx ctx;

I'd like to see this broken out into some functions, and avoid
as much code as possible within ifdefs.  Perhaps

some_function (...)
{
#ifndef OBJECT_FORMAT_ELF
  return;
#endif
  // everything else
}

I think it also doesn't help review that there are no comments
at all, and a preponderance of description-less variable names
like "ref" and "ref2".


r~