Re: [GOOGLE] Report the difference between profiled and guessed or annotated branch probabilities.

[Yi Yang <ahyangyi at google dot com>]

Instead of storing percentages of the branch probabilities, store them
times REG_BR_PROB_BASE.

On Mon, Jun 30, 2014 at 3:26 PM, Yi Yang <ahyangyi@google.com> wrote:
> Fixed. (outputting only the integer percentage)
>
> On Mon, Jun 30, 2014 at 2:20 PM, Yi Yang <ahyangyi@google.com> wrote:
>> This is intermediate result, which is meant to be consumed by further
>> post-processing. For this reason I'd prefer to put a number without
>> that percentage sign.
>>
>> I'd just output (int)(probability*100000000+0.5). Does this look good
>> for you? Or maybe change that to 1000000 since six digits are more
>> than enough. I don't see a reason to intentionally drop precision
>> though.
>>
>> Note that for the actual probability, the best way to store it is to
>> store the edge count, since the probability is just
>> edge_count/bb_count. But this causes disparity in the formats of the
>> two probabilities.
>>
>> On Mon, Jun 30, 2014 at 2:12 PM, Dehao Chen <dehao@google.com> wrote:
>>> Let's use %d to replace %f (manual conversion, let's do xx%).
>>>
>>> Dehao
>>>
>>> On Mon, Jun 30, 2014 at 2:06 PM, Yi Yang <ahyangyi@google.com> wrote:
>>>> Fixed.
>>>>
>>>> Also, I spotted some warnings caused by me using "%lf"s in snprintf().
>>>> I changed these to "%f" and tested.
>>>>
>>>>
>>>> On Mon, Jun 30, 2014 at 1:49 PM, Dehao Chen <dehao@google.com> wrote:
>>>>> You don't need extra space to store file name in locus_information_t.
>>>>> Use pointer instead.
>>>>>
>>>>> Dehao
>>>>>
>>>>>
>>>>> On Mon, Jun 30, 2014 at 1:36 PM, Yi Yang <ahyangyi@google.com> wrote:
>>>>>>
>>>>>> I refactored the code and added comments. A bug (prematurely breaking
>>>>>> from a loop) was fixed during the refactoring.
>>>>>>
>>>>>> (My last mail was wrongly set to HTML instead of plain text. I
>>>>>> apologize for that.)
>>>>>>
>>>>>> 2014-06-30  Yi Yang  <ahyangyi@google.com>
>>>>>>
>>>>>>     * auto-profile.c (get_locus_information)
>>>>>>     (fill_invalid_locus_information, record_branch_prediction_results)
>>>>>>     (afdo_calculate_branch_prob, afdo_annotate_cfg): Main comparison and
>>>>>>     reporting logic.
>>>>>>     * cfg-flags.def (PREDICTED_BY_EXPECT): Add an extra flag representing
>>>>>>     an edge's probability is predicted by annotations.
>>>>>>     * predict.c (combine_predictions_for_bb): Set up the extra flag on an
>>>>>>     edge when appropriate.
>>>>>>     * common.opt (fcheck-branch-annotation)
>>>>>>     (fcheck-branch-annotation-threshold=): Add an extra GCC option to turn
>>>>>>     on report
>>>>>>
>>>>>> On Fri, Jun 27, 2014 at 3:20 PM, Xinliang David Li <davidxl@google.com> wrote:
>>>>>> > Hi Yi,
>>>>>> >
>>>>>> > 1) please add comments before new functions as documentation -- follow
>>>>>> > the coding style guideline
>>>>>> > 2) missing documenation on the new flags (pointed out by Gerald)
>>>>>> > 3) Please refactor the check code in afdo_calculate_branch_prob into a
>>>>>> > helper function
>>>>>> >
>>>>>> > 4) the change log is not needed for google branches, but if provided,
>>>>>> > the format should follow the style guide (e.g, function name in () ).
>>>>>> >
>>>>>> > David
>>>>>> >
>>>>>> >
>>>>>> > On Fri, Jun 27, 2014 at 11:07 AM, Yi Yang <ahyangyi@google.com> wrote:
>>>>>> >> Hi,
>>>>>> >>
>>>>>> >> This patch adds an option. When the option is enabled, GCC will add a
>>>>>> >> record about it in an elf section called
>>>>>> >> ".gnu.switches.text.branch.annotation" for every branch.
>>>>>> >>
>>>>>> >> gcc/
>>>>>> >>
>>>>>> >> 2014-06-27 Yi Yang <ahyangyi@google.com>
>>>>>> >>
>>>>>> >>         * auto-profile.c: Main comparison and reporting logic.
>>>>>> >>         * cfg-flags.def: Add an extra flag representing an edge's
>>>>>> >> probability is predicted by annotations.
>>>>>> >>         * predict.c: Set up the extra flag on an edge when appropriate.
>>>>>> >>         * common.opt: Add an extra GCC option to turn on this report mechanism

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