https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54052
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rguenth at gcc dot gnu.org,
| |rsandifo at gcc dot gnu.org
Summary|g++ takes excessive time in |[11/12/13/14 Regression]
|opt and generate phase; can |g++ takes excessive time in
|lead to Segmentation Fault |opt and generate phase; can
|when not enough memory |lead to Segmentation Fault
|available |when not enough memory
| |available
Last reconfirmed|2018-09-18 00:00:00 |2024-2-16
Target Milestone|--- |11.5
--- Comment #10 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 14:
-O0 800MB in 10s
-O1 1.2GB in 30min (!)
SSA construction (rtl_ssa::function_info::place_phis) takes forever.
forward prop :1669.98 ( 95%)
combiner : 34.80 ( 2%)
TOTAL :1749.78
unsurprisingly -fno-forward-propagate helps a lot, compile-time down to 76s.
GCC 11 seems to be similarly slow, stopped after some minutes,
-fno-forward-propagate helps as well (63s).
GCC 10 (no RTL SSA):
-O1 1GB in 70s
dominance frontiers : 13.69 ( 19%)
combiner : 36.62 ( 50%)
so there's at least a big regression from GCC 10 here.
The testcase might be a bit large to work with and I didn't profile but
for -O1 we need some "fix" here, even if it might be simply giving up
for some CFG + nregs characteristics that makes things blow up here.
