https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98863
--- Comment #45 from Richard Biener <rguenth at gcc dot gnu.org> ---
perf profile from non-bootstrapped, release checking enabled lto1 for ltrans34
on a 3900X (so plenty of L3):
Samples: 1M of event 'cycles:u', Event count (approx.): 1572289976832
Overhead Samples Command Shared Object Symbol
7.10% 96925 lto1-ltrans lto1 [.] bitmap_and_into
#
6.37% 87172 lto1-ltrans lto1 [.]
bitmap_list_insert_element_after #
5.84% 80125 lto1-ltrans lto1 [.] bitmap_set_bit
#
5.71% 78151 lto1-ltrans lto1 [.] bitmap_ior_into
#
5.70% 78041 lto1-ltrans lto1 [.] bitmap_bit_p
#
3.71% 50632 lto1-ltrans lto1 [.] bitmap_and
#
3.48% 47914 lto1-ltrans lto1 [.] df_count_refs
#
2.87% 39504 lto1-ltrans lto1 [.]
lra_create_live_ranges_1 #
2.45% 33656 lto1-ltrans lto1 [.] bitmap_elt_ior
#
2.39% 32794 lto1-ltrans lto1 [.]
pre_and_rev_post_order_compute_fn #
2.34% 32200 lto1-ltrans lto1 [.] update_pseudo_point
#
2.03% 27707 lto1-ltrans lto1 [.] bitmap_ior_and_compl
#
1.79% 24445 lto1-ltrans lto1 [.]
bitmap_and_compl_into #
1.52% 20804 lto1-ltrans lto1 [.] df_worklist_dataflow
#
1.45% 19838 lto1-ltrans lto1 [.] bitmap_copy
#
1.35% 18690 lto1-ltrans lto1 [.]
get_immediate_dominator #
1.32% 18127 lto1-ltrans lto1 [.] update_ssa
#
1.26% 17562 lto1-ltrans lto1 [.]
determine_value_range #
1.09% 14873 lto1-ltrans lto1 [.]
rewrite_update_dom_walker::before_dom_children #
1.08% 14777 lto1-ltrans lto1 [.] compute_idf
#
1.05% 14349 lto1-ltrans lto1 [.]
compute_dominance_frontiers #
0.94% 12956 lto1-ltrans libc-2.26.so [.]
__memset_avx2_unaligned_erms #
at some point I wondered why keeping DF_LIVE around pays off, but we don't
have an easy knob to disable it at -O2. Not many passes need LIVE, most
do with LR.
