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Re: Fix dumping of branch predictor hitrates


On Sun, Apr 17, 2016 at 9:13 AM, Jan Hubicka <hubicka@ucw.cz> wrote:
> Hi,
> this patch fixes infrastructure used by branch prediction code to collect
> information about prediction hitrates that is needed to verify their
> performance.
>
> We used to read profile first and then do profile estimation, nowdays passes
> are run in the opposite order. Because dumping happens during estimation, we
> no longer get the information.  This patch simply re-runs the branch prediction
> w/o modifying the profile when -fdump-ipa-profile is used.
>
> Profile estimation and maintenance code was not very actively developed
> in recent years and there are some dead ends. This stage 1 I would like to fix
> them, update the APIs to be more robust and use sreals instaed of fixedpoint
> arithmetics.
>
> Bootstrapped/regtested x86_64-linux, comitted.
>
> Honza
>
>         * predict.c (combine_predictions_for_bb): Add dry_run parmaeter.
>         (tree_estimate_probability): Likewise.
>         (pass_profile::execute): Update.
>         (report_predictor_hitrates): New function.
>         * profile.c (compute_branch_probabilities): Use it.
>         * predict.h (report_predictor_hitrates): Declare.
>
>         * analyze_brprob: Update comment.

This caused:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70706


-- 
H.J.


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