[Bug middle-end/52066] New: IRA and reginfo initialization too expensive

[Bug middle-end/52066] New: IRA and reginfo initialization too expensive

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52066

             Bug #: 52066
           Summary: IRA and reginfo initialization too expensive
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: jakub@gcc.gnu.org


On compilation of an empty file, we spend almost half of the runtime on
IRA and reginfo cost initialization.

Inlining reg_class_subset_p and reg_classes_intersect_p gives us at least tiny
part of compile time back, at the cost of some small code growth.
For --enable-checking=release x86_64-linux cc1:

~/timing --drop 20 -c 2500 ./cc1.vanilla empty.c -quiet
Strip out best and worst 500 realtime results
minimum: 0.006243475 sec real / 0.000018634 sec CPU
maximum: 0.032220578 sec real / 0.000203440 sec CPU
average: 0.006542800 sec real / 0.000036352 sec CPU
stdev  : 0.000050402 sec real / 0.000004406 sec CPU
~/timing --drop 20 -c 2500 ./cc1 empty.c -quiet
Strip out best and worst 500 realtime results
minimum: 0.006115241 sec real / 0.000017569 sec CPU
maximum: 0.033226603 sec real / 0.000197238 sec CPU
average: 0.006384943 sec real / 0.000036349 sec CPU
stdev  : 0.000049180 sec real / 0.000004284 sec CPU

readelf -WS cc1{.vanilla,} | grep '\text'
  [12] .text             PROGBITS        00000000004b21a0 0b21a0 78e7b4 00  AX 
0   0 16
  [12] .text             PROGBITS        00000000004b21a0 0b21a0 78ed34 00  AX 
0   0 16

[Bug middle-end/52066] IRA and reginfo initialization too expensive

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52066

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-01-31 13:09:39 UTC ---
Created attachment 26531
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26531
patch

Patch to inline them.  Quite ugly, but I can't use extern inline
__attribute__((gnu_inline)), because it uses static inline functions, and
unfortunately some callers of these functions can't include hard-reg-set.h
(targhooks.c).

[Bug middle-end/52066] IRA and reginfo initialization too expensive

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52066

--- Comment #2 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-01-31 13:21:23 UTC ---
PR44440?

[Bug middle-end/52066] IRA and reginfo initialization too expensive

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52066

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-01-31 14:54:32 UTC ---
Created attachment 26535
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26535
i386 patch

Incremental patch to speed up i386 *CLASS_P macros.  I agree it isn't as clean
as defining them using the subsets (now used just in rtl checking during
initialization), but seems to be faster.  Timing with both patches:

~/timing --drop 20 -c 2500 ./cc1 empty.c -quiet
Strip out best and worst 500 realtime results
minimum: 0.006076317 sec real / 0.000018264 sec CPU
maximum: 0.034520375 sec real / 0.000205298 sec CPU
average: 0.006284155 sec real / 0.000036616 sec CPU
stdev  : 0.000048897 sec real / 0.000004400 sec CPU

  [12] .text             PROGBITS        00000000004b21a0 0b21a0 78e774 00  AX 
0   0 16

(i.e. it completely undoes all the code growth by the first patch).

[Bug middle-end/52066] IRA and reginfo initialization too expensive

[steven at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52066

Steven Bosscher <steven at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |steven at gcc dot gnu.org

--- Comment #4 from Steven Bosscher <steven at gcc dot gnu.org> 2012-10-09 20:46:39 UTC ---
(In reply to comment #1)
> Patch to inline them.  Quite ugly, but I can't use extern inline
> __attribute__((gnu_inline)), because it uses static inline functions, and
> unfortunately some callers of these functions can't include hard-reg-set.h
> (targhooks.c).

Huh, if it's ok to know about reg-classes in targhooks, why is it not also OK
to know about HARD_REG_SET?