> On Thu, May 26, 2011 at 12:45 PM, Jan Hubicka <hubi...@ucw.cz> wrote: > >> > >> This looks all very hackish with no immediate benefit mostly because > >> of the use of lto_output_string. I think what you should do instead > >> is split up lto_output_string_with_length into the piece that streams > >> the string itself to the string-stream and returns an index into it > >> and the piece streaming the index to the specified stream. Then you > >> can simply bitpack that index and the two int line / column fields. > > > > Hmm, I plan to optimize string streaming (since we always stream one uleb to > > set it is non-NULL that can be easilly handled by assigining NULL string > > index > > 0). How precisely you however suggest to bitpack line/column and string > > offset > > together? > > Similar to how you suggested, stream bits for a changed flag but > instead of finishing the bitpack simply stream HOST_BITS_PER_INT > bits for line (if changed), colunn (if changed) and file string index (if > changed and the index is 'int'). > > I mostly want to avoid the split between the changed bits and the > data output, esp. breaking the bitpack.
Well, that won't get me for < 1 byte overhead when location is unchanged or unknown (that is true for about half of cases in my stats). Additionally HOST_BITS_PER_INT is host sensitive and wasteful compared to ulebs here as the line numbers, file indexes and columns are all usually small numbers, so they ought to fit in 16, 8 and 8 bits most of time. So we would end up in need of inventing something like uleb in bitpack? Honza
