[PATCH][stage1] Support profile (BB counts and edge probabilities) in GIMPLE FE.

[Martin Liška]

On 4/8/19 11:11 AM, Richard Biener wrote:
> On Fri, Apr 5, 2019 at 2:32 PM Martin Liška <mliska@suse.cz> wrote:
>>
>> Hi.
>>
>> The patch adds support for profile for GIMPLE FE. That can be useful
>> in the future.
>>
>> Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
>>
>> Ready to be installed after stage1 opens?
> 
> Hmm, I guess to be useful we need the profile quality indicators as well
> (and think about a proper syntax here since it seems related).

I wanted to make it easy, buy yes. We should implement that.

> 
> Btw, do BB counts and edge probabilities not have a relation?

Yes, they should match. But you have optimizations that make some discrepancies.
So that I would implement support for both of them.

>  If so why
> do we need both?  In predict.c we also look at ENTRY_BLOCK->count
> so we need a place to set that as well.  We should probably set
> edge probabilities of fallthru edges properly during our "CFG build".
> 
> +    goto __BB3(44739243);
> 
> since we eventually want to add other flags this syntactically
> should maybe be goto __BB3(guessed(44739243)); and similar
> for the __BB count case (just s/count/quality/).

The syntax works for me.

> 
> The entry block count could be sticked to __GIMPLE (ssa,guessed(N))
> for example.  There's also the exit block, not sure if we ever look at
> its count, so __GIMPLE (ssa,guessed(N[,M])) might be a possibility
> if we always have the same quality here (probably not...).

I'll check it.

> 
> Otherwise thanks for trying ;)
> 
> Richard.
> 
>> Thanks,
>> Martin
>>
>> gcc/ChangeLog:
>>
>> 2019-04-05  Martin Liska  <mliska@suse.cz>
>>
>>         * gimple-pretty-print.c (dump_gimple_bb_header):
>>         Dump BB count.
>>         (pp_cfg_jump): Dump edge probability.
>>         * profile-count.h (get_raw_value): New function.
>>         (from_raw_value): Likewise.
>>
>> gcc/c/ChangeLog:
>>
>> 2019-04-05  Martin Liska  <mliska@suse.cz>
>>
>>         * gimple-parser.c (struct gimple_parser): Add frequency
>>         for gimple_parser_edge.
>>         (gimple_parser::push_edge): Add new argument frequency.
>>         (c_parser_gimple_parse_bb_spec): Parse also frequency
>>         if present.
>>         (c_parser_parse_gimple_body): Set edge probability.
>>         (c_parser_gimple_compound_statement): Consume token
>>         before calling c_parser_gimple_goto_stmt.
>>         Parse BB counts.
>>         (c_parser_gimple_statement): Pass new argument.
>>         (c_parser_gimple_goto_stmt): Likewise.
>>         (c_parser_gimple_if_stmt): Likewise.
>>
>> gcc/testsuite/ChangeLog:
>>
>> 2019-04-05  Martin Liska  <mliska@suse.cz>
>>
>>         * gcc.dg/gimplefe-37.c: New test.
>> ---
>>  gcc/c/gimple-parser.c              | 116 +++++++++++++++++++++++------
>>  gcc/gimple-pretty-print.c          |   8 ++
>>  gcc/profile-count.h                |  15 ++++
>>  gcc/testsuite/gcc.dg/gimplefe-37.c |  27 +++++++
>>  4 files changed, 144 insertions(+), 22 deletions(-)
>>  create mode 100644 gcc/testsuite/gcc.dg/gimplefe-37.c
>>
>>