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Re: [PATCH][RFC] bitpacking rewrite
- From: Jan Hubicka <hubicka at ucw dot cz>
- To: Richard Guenther <rguenther at suse dot de>
- Cc: gcc-patches at gcc dot gnu dot org, Jan Hubicka <jh at suse dot de>, Diego Novillo <dnovillo at google dot com>
- Date: Sat, 12 Jun 2010 17:07:00 +0200
- Subject: Re: [PATCH][RFC] bitpacking rewrite
- References: <alpine.LNX.2.00.1006121402060.1429@zhemvz.fhfr.qr>
>
> The following preliminary patch rewrites bitpacking to happen
> word-by-word and on the stack (well, in the preliminary form
> only on the stack after inlining).
>
> Comments?
I like the change. Probably instead of bp/bp_s game, I would go with
adding &bp to every caller, but I do not care.
> + static inline void
> + bp_pack_value (struct bitpack_d *bp, bitpack_word_t val, unsigned nbits)
> + {
> + bitpack_word_t word = bp->word;
> + int pos = bp->pos;
> + /* If val does not fit into the current bitpack word switch to the
> + next one. */
> + if (pos + nbits > BITS_PER_BITPACK_WORD)
> + {
> + lto_output_uleb128_stream ((struct lto_output_stream *) bp->stream, word);
Hehe, I never got to idea that one can actually output the bitpack when it overflows
first word ;)
I guess you want to add some checking asserts that nbits does not exceed BITS_PER_BITPACK_WORD.
So next step would be to optimize ulebs/slebs, right? :)
Honza