[Bug middle-end/110489] Slow building virtual.c.i from p11-kit

["rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110489

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-06-30
           Assignee|unassigned at gcc dot gnu.org      |rguenth at gcc dot gnu.org

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Samples: 45K of event 'cycles', Event count (approx.): 51356148788              
Overhead       Samples  Command  Shared Object       Symbol                     
   2.57%          1169  cc1      libc-2.31.so        [.] _int_malloc
   1.54%           700  cc1      cc1                 [.] bitmap_set_bit
   1.52%           692  cc1      libc-2.31.so        [.] malloc
   1.32%           602  cc1      libc-2.31.so        [.] _int_free
   1.31%           598  cc1      cc1                 [.] record_reg_classes
   1.04%           476  cc1      cc1                 [.] constrain_operands
   0.81%           368  cc1      cc1                 [.] solve_constraints
   0.79%           360  cc1      cc1                 [.] cse_insn
   0.78%           357  cc1      cc1                 [.] ggc_internal_alloc
   0.76%           347  cc1      libc-2.31.so        [.] free
   0.73%           330  cc1      cc1                 [.] statistics_fini_pass

it's pointing at things I've seen multiple times, but I think investigating
why memory allocation is so high up in the profile would be good.  There
are some users like dom_info::dom_init which hit hard on the allocator
without good reason but then it's only few per function but as seen this
testcase has many of them.  Likewise ipa_sra_summarize_function seems to
have 99% cost in memory allocation.  Doing more on-demand initialization
might help here.

I have a patch for the statistics_finish_pass hit.