https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97623
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |needs-bisection
--- Comment #13 from Richard Biener <rguenth at gcc dot gnu.org> ---
OK, on that testcase the good news is that GCC 10 is much better than GCC 9
resulting in -O2 -fno-code-hoisting
tree PRE : 2.25 ( 50%) 0.05 ( 20%) 2.32 ( 49%)
31794 kB ( 20%)
TOTAL : 4.47 0.25 4.72
161356 kB
compared to GCC 9 where I can indeed reproduce
tree PRE : 37.81 ( 95%) 0.04 ( 13%) 37.96 ( 95%)
32604 kB ( 20%)
TOTAL : 39.63 0.30 39.99
161584 kB
suspicious are diffs in insertions and insert iterations:
Insertions: 1258
insert iterations == 3: 1
Eliminated: 1553
vs bad:
Insertions: 8616
insert iterations == 128: 1
Eliminated: 8955
I wonder what triggered this change ...
On patched trunk we're in the same ballpark as GCC 10 but without requiring
-fno-code-hoisting. The testcase is still an interesting one for PRE
(50% of the compile spent there is a bit much, even if just 2 seconds).
