On Sun, Oct 7, 2012 at 11:27 PM, Steven Bosscher <stevenb....@gmail.com> wrote:
> On Sun, Oct 7, 2012 at 5:59 PM, Vladimir Makarov wrote:
>> The following patch speeds LRA up more on PR54146. Below times for
>> compilation of the test on gcc17.fsffrance.org (an AMD machine):
>>
>> Before:
>> real=1214.71 user=1192.05 system=22.48
>> After:
>> real=1144.37 user=1124.31 system=20.11
>
> Hi Vlad,
>
> The next bottle-neck in my timings is in
> lra-eliminate.c:lra_eliminate(), in this loop:
>
> FOR_EACH_BB (bb)
> FOR_BB_INSNS_SAFE (bb, insn, temp)
> {
> if (bitmap_bit_p (&insns_with_changed_offsets, INSN_UID (insn)))
> process_insn_for_elimination (insn, final_p);
> }
>
> The problem is in bitmap_bit_p. Random access to a large bitmap can be
> very slow.
>
> I'm playing with a patch to expand the insns_with_changed_offsets
> bitmap to an sbitmap, and will send a patch if this works better.
Or make insns_with_changed_offsets a VEC of insns (or a pointer-set).
Richard.
> Ciao!
> Steven
