Re: macros, debug information, and parse_macro_definition

[Daniel Berlin <dberlin@dberlin.org>]

On Tuesday, April 29, 2003, at 10:55  AM, Andrew Cagney wrote:

>
>> These encodings are simple enough that I wouldn't expect them to
>> change over time.
>> I would think it more likely that there would be a bug, either in
>> gcc's encoding of them or in gdb's processing of them.  And if the
>> code is duplicated, then both locations need to be modified to fix the
>> bug -- with the attendant risk that someone will modify one and forget
>> to modify the other.  Or will modify it, but accidentally make it
>> slightly different.
>
>
>> I don't know how people would feel about having STABS have a
>> description of the encoding combined with a caveat that the DWARF
>> 2.0.0 spec is authoritative.  I would certainly prefer that the STABS
>> document remain self contained.
>
> I think this is a good strategy.  It's already a ``gcc extension'',  
> and stealing an existing (known to be working) spec is always a good 
> strategy :-)
>
> Have you thought about link time information compression?  One of the 
> complaints leveled at the macro stuff is the size of the resultant 
> debug info.

It's trivial to do macro information compression, unlike normal dwarf2 
info compression, because the macro info has no references. It is what 
it is.  With a smart algorithm (it's a bit tricky to keep the semantics 
the same after merging all the macro infos), you could simply take all 
the macro infos, merge them, make one macro info, and point all the 
debug sections at it.
I think, anyway.

>
> Andrew
>
>