[Bug middle-end/77484] [6/7 Regression] Static branch predictor causes ~6-8% regression of SPEC2000 GAP

[hubicka at ucw dot cz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77484

--- Comment #20 from Jan Hubicka <hubicka at ucw dot cz> ---
Hi,
it turns out that Martin added another column to his statistics script which I
have misinterpretted.
https://gcc.opensuse.org/SPEC/CINT/sb-terbium-head-64/recent.html also shows
interesting reaction
to the change.  I will update the probabilities to correct values one by one
and let us see
how benchmarks react.  Is changing one a day enough for periodic testers to
catch up?

The hitrates on spec2k6 combined with spec v6 is as follows.
It means that indirect call should have 14%, call  67% and polymorphic call
should have oposite outcime and 59% The statistic samples are quite small and
dominated by one use, so we may diverge from those values if it seem to make
sense.

Honza


COMBINED
========
HEURISTICS                               BRANCHES  (REL)  BR. HITRATE          
 HITRATE       COVERAGE COVERAGE  (REL)
loop guard with recursion                      13   0.0%       92.31%   85.06%
/  85.06%     6672440267    6.67G   0.4%
Fortran loop preheader                         42   0.0%       97.62%   97.78%
/  99.07%        1448718    1.45M   0.0%
loop iv compare                                71   0.1%       78.87%   49.26%
/  63.89%      163168352  163.17M   0.0%
loop exit with recursion                       85   0.1%       75.29%   84.89%
/  86.96%     9873741435    9.87G   0.6%
extra loop exit                                98   0.1%       71.43%   31.39%
/  76.96%      312263024  312.26M   0.0%
recursive call                                121   0.1%       64.46%   37.55%
/  82.78%      531996473  532.00M   0.0%
Fortran repeated allocation/deallocation      392   0.4%      100.00%  100.00%
/ 100.00%            630   630.00   0.0%
guess loop iv compare                         402   0.4%       90.05%   95.82%
/  96.04%     5683151771    5.68G   0.3%
indirect call                                 425   0.4%       52.00%   14.06%
/  91.41%     3815332963    3.82G   0.2%
Fortran zero-sized array                      549   0.6%       99.64%  100.00%
/ 100.00%       20794317   20.79M   0.0%
const return                                  651   0.7%       94.93%   84.04%
/  93.18%     1067774653    1.07G   0.1%
null return                                   716   0.7%       92.18%   91.83%
/  93.39%     3421321956    3.42G   0.2%
negative return                               734   0.8%       97.14%   64.62%
/  65.01%     4744886315    4.74G   0.3%
continue                                      773   0.8%       66.11%   79.71%
/  87.43%    29089649102   29.09G   1.6%
polymorphic call                              803   0.8%       43.59%   59.05%
/  86.63%     3828555030    3.83G   0.2%
Fortran fail alloc                            944   1.0%      100.00%  100.00%
/ 100.00%         167691  167.69K   0.0%
Fortran overflow                             1237   1.3%      100.00%  100.00%
/ 100.00%       55197159   55.20M   0.0%
loop guard                                   1861   1.9%       48.90%   69.86%
/  84.62%    17979028127   17.98G   1.0%
noreturn call                                3769   3.9%       99.95%  100.00%
/ 100.00%     8175053425    8.18G   0.5%
loop exit                                    5017   5.2%       83.50%   90.01%
/  91.68%   143815212145  143.82G   8.1%
opcode values positive (on trees)            5763   6.0%       66.23%   60.41%
/  86.25%    43349211449   43.35G   2.4%
loop iterations                              6276   6.6%       99.94%   78.54%
/  78.54%   662671304506  662.67G  37.3%
early return (on trees)                      9512   9.9%       61.02%   58.05%
/  85.82%    56222551226   56.22G   3.2%
pointer (on trees)                          10969  11.5%       63.29%   75.18%
/  89.33%    23318221976   23.32G   1.3%
opcode values nonequal (on trees)           11633  12.2%       63.23%   74.53%
/  85.23%   118246028039  118.25G   6.7%
guessed loop iterations                     13631  14.2%       96.54%   92.61%
/  93.12%   417886815060  417.89G  23.5%
call                                        20747  21.7%       54.47%   67.24%
/  92.56%    50096613362   50.10G   2.8%