On Mon, 14 Sep 2020, Jakub Jelinek wrote:
> On Mon, Sep 14, 2020 at 09:31:52AM +0200, Richard Biener wrote:
> > But does it make any noticable difference in the end? Using
>
> Yes.
>
> > bp_pack_var_len_unsigned just causes us to [u]leb encode half-bytes
> > rather than full bytes. Using hardcoded 8/16/32/64 makes it still
> > dependent on what 'int' is at maximum on the host.
> >
> > That is, I'd indeed prefer bp_pack_var_len_unsigned over hard-coding
> > 8, 16, etc., but can you share a size comparison of the bitpack?
> > I guess with bp_pack_var_len_unsigned it might shrink in half
> > compared to the current code and streaming standard -O2?
>
> So, I've tried
> --- gcc/tree-streamer-out.c.jj 2020-07-28 15:39:10.079755251 +0200
> +++ gcc/tree-streamer-out.c 2020-09-14 10:31:29.106957258 +0200
> @@ -489,7 +489,11 @@ streamer_write_tree_bitfields (struct ou
> pack_ts_translation_unit_decl_value_fields (ob, &bp, expr);
>
> if (CODE_CONTAINS_STRUCT (code, TS_OPTIMIZATION))
> +{
> +long ts = ob->main_stream->total_size;
> cl_optimization_stream_out (ob, &bp, TREE_OPTIMIZATION (expr));
> +fprintf (stderr, "total_size %ld\n", (long) (ob->main_stream->total_size -
> ts));
> +}
>
> if (CODE_CONTAINS_STRUCT (code, TS_CONSTRUCTOR))
> bp_pack_var_len_unsigned (&bp, CONSTRUCTOR_NELTS (expr));
> hack without and with the following patch on a simple small testcase with
> -O2 -flto.
> Got 574 bytes without the opc-save-gen.awk change and 454 bytes with it,
> that is ~ 21% saving on the TREE_OPTIMIZATION streaming.
OK, not spectacular but I guess good enough. So I'd say the below
patch using bp_pack_var_len_{int,unsigned} is OK.
Thanks,
Richard.
> 2020-09-14 Jakub Jelinek <ja...@redhat.com>
>
> * optc-save-gen.awk: In cl_optimization_stream_out use
> bp_pack_var_len_{int,unsigned} instead of bp_pack_value. In
> cl_optimization_stream_in use bp_unpack_var_len_{int,unsigned}
> instead of bp_unpack_value. Formatting fix.
>
> --- gcc/optc-save-gen.awk.jj 2020-09-14 09:04:35.879854156 +0200
> +++ gcc/optc-save-gen.awk 2020-09-14 10:38:47.722424942 +0200
> @@ -1257,8 +1257,10 @@ for (i = 0; i < n_opt_val; i++) {
> otype = var_opt_val_type[i];
> if (otype ~ "^const char \\**$")
> print " bp_pack_string (ob, bp, ptr->" name", true);";
> + else if (otype ~ "^unsigned")
> + print " bp_pack_var_len_unsigned (bp, ptr->" name");";
> else
> - print " bp_pack_value (bp, ptr->" name", 64);";
> + print " bp_pack_var_len_int (bp, ptr->" name");";
> }
> print " for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof
> (ptr->explicit_mask[0]); i++)";
> print " bp_pack_value (bp, ptr->explicit_mask[i], 64);";
> @@ -1274,14 +1276,15 @@ print "{";
> for (i = 0; i < n_opt_val; i++) {
> name = var_opt_val[i]
> otype = var_opt_val_type[i];
> - if (otype ~ "^const char \\**$")
> - {
> - print " ptr->" name" = bp_unpack_string (data_in, bp);";
> - print " if (ptr->" name")";
> - print " ptr->" name" = xstrdup (ptr->" name");";
> + if (otype ~ "^const char \\**$") {
> + print " ptr->" name" = bp_unpack_string (data_in, bp);";
> + print " if (ptr->" name")";
> + print " ptr->" name" = xstrdup (ptr->" name");";
> }
> + else if (otype ~ "^unsigned")
> + print " ptr->" name" = (" var_opt_val_type[i] ")
> bp_unpack_var_len_unsigned (bp);";
> else
> - print " ptr->" name" = (" var_opt_val_type[i] ") bp_unpack_value
> (bp, 64);";
> + print " ptr->" name" = (" var_opt_val_type[i] ")
> bp_unpack_var_len_int (bp);";
> }
> print " for (size_t i = 0; i < sizeof (ptr->explicit_mask) / sizeof
> (ptr->explicit_mask[0]); i++)";
> print " ptr->explicit_mask[i] = bp_unpack_value (bp, 64);";
>
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)
