On 11/14/23 03:38, Lehua Ding wrote:
This is perfectly fine, the code inside the live_subreg problem has a
branch that goes through similar logic to live_reg if it finds no
subreg inside the program. Then when the optimization level is less
than 2, it doesn't track the subreg. By the way, I'd like to ask you
if you have certain programs where RA has a big impact on compilation
time to offer? Or any suggestions about it?
I've analyzed effect of your patches to -O2 compilation time on
compilation of some old version of combine.c. The total GCC compilation
time increased by about 3%. I used x86_64 release mode compiler. Here
are my more detail findings:
RA compile time increased by 43%.
54% of this increase is due df_analyze time increase and 38% is due to
overall ira_color increase (assign_hard_reg execution time increased in
50 times but still such big increase is 1/3 of overall ira_color increase).
The rest (about 10%) of overall RA increase is mostly LRA increase due
to lra_create_live_ranges.
To see where 6% GCC compilation time increase on SPEC2017 is spent would
be more interesting but it needs a lot of time for analysis.
