https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80960
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to work| |4.3.4
Known to fail| |4.8.5
--- Comment #23 from Richard Biener <rguenth at gcc dot gnu.org> ---
So now I see
> /usr/bin/time gfortran-4.3 t.f90 -fdefault-integer-8 -O2 -ftime-report
combiner : 0.25 ( 2%) usr 0.00 ( 0%) sys 0.24 ( 2%) wall
9947 kB ( 5%) ggc
TOTAL : 15.43 0.21 15.65
220667 kB
15.59user 0.24system 0:15.84elapsed 99%CPU (0avgtext+0avgdata
607492maxresident)k
0inputs+0outputs (0major+164981minor)pagefaults 0swaps
> /usr/bin/time gfortran-4.8 t.f90 -fdefault-integer-8 -O2 -ftime-report
combiner : 90.22 (48%) usr 1.07 (63%) sys 91.33 (48%) wall
1757344 kB (88%) ggc
TOTAL : 188.29 1.70 190.04
2000994 kB
188.43user 1.73system 3:10.21elapsed 99%CPU (0avgtext+0avgdata
6523136maxresident)k
0inputs+0outputs (0major+1727565minor)pagefaults 0swaps
> /usr/bin/time gfortran-7 t.f90 -fdefault-integer-8 -O2 -fno-checking
> -ftime-report
combiner : 67.18 (64%) usr 0.56 (60%) sys 67.76 (64%) wall
2701121 kB (60%) ggc
TOTAL : 105.40 0.93 106.36
4530486 kB
105.54user 0.99system 1:46.58elapsed 99%CPU (0avgtext+0avgdata
3297696maxresident)k
48248inputs+0outputs (7major+835050minor)pagefaults 0swaps
> /usr/bin/time gfortran-10 t.f90 -fdefault-integer-8 -O2 -fno-checking
> -ftime-report
combiner : 0.24 ( 0%) 0.00 ( 0%) 0.22 ( 0%)
10376 kB ( 1%)
TOTAL : 52.02 0.49 52.52
1876905 kB
52.16user 0.52system 0:52.71elapsed 99%CPU (0avgtext+0avgdata
1831392maxresident)k
55032inputs+0outputs (8major+539965minor)pagefaults 0swaps
(that combine number prevails on trunk as well, I can't spot any code
that disables combine on large BBs so not sure what goes on here)
At least clearly GCC 4.8.5 is bad as well and there's clear progression
on both memory use and compile-time, still not up to the level of GCC 4.3.
Interestingly memory-wise it all points to RTL DSE (GCC 10), likely
because of DF. Eventually post-reload we can simplify some things...
dead store elim2 : 6.90 ( 12%) 0.20 ( 27%) 7.12 ( 12%)
1641076 kB ( 87%)
