For 20001226-1.c at -O3, i get:
Execution times (seconds)
tree VRP : 11.32 (10%) usr 0.08 ( 9%) sys 11.68 (10%) wall
3194 kB ( 8%) ggc
tree operand scan : 28.39 (26%) usr 0.17 (18%) sys 29.00 (25%) wall
2722 kB ( 7%) dominance frontiers : 35.35 (32%) usr 0.13 (14%) sys 36.18
(31%) wall 0 kB ( 0%) ggc
TOTAL : 110.77 0.92 116.23
38719 kB
gprof shows that all but one of the calls to compute dominance frontiers come
from update_ssa (probably because people are using TODO_update_ssa instead of
TODO_update_ssa_no_phi).
The operand scan time is also mostly update_ssa, checking for modified
statements
--
Summary: update_ssa very very very slow
Product: gcc
Version: 4.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: dberlin at gcc dot gnu dot org
CC: gcc-bugs at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=23902
