Re: -fdump-passes -fenable-xxx=func_name_list

[Xinliang David Li <davidxl@google.com>]

On Wed, Jun 1, 2011 at 12:29 PM, Richard Guenther
<richard.guenther@gmail.com> wrote:
> On Wed, Jun 1, 2011 at 6:16 PM, Xinliang David Li <davidxl@google.com> wrote:
>> On Wed, Jun 1, 2011 at 1:51 AM, Richard Guenther
>> <richard.guenther@gmail.com> wrote:
>>> On Wed, Jun 1, 2011 at 1:34 AM, Xinliang David Li <davidxl@google.com> wrote:
>>>> The following patch implements the a new option that dumps gcc PASS
>>>> configuration. The sample output is attached.  There is one
>>>> limitation: some placeholder passes that are named with '*xxx' are
>>>> note registered thus they are not listed. They are not important as
>>>> they can not be turned on/off anyway.
>>>>
>>>> The patch also enhanced -fenable-xxx and -fdisable-xx to allow a list
>>>> of function assembler names to be specified.
>>>>
>>>> Ok for trunk?
>>>
>>> Please split the patch.
>>>
>>> I'm not too happy how you dump the pass configuration.  Why not simply,
>>> at a _single_ place, walk the pass tree?  Instead of doing pieces of it
>>> at pass execution time when it's not already dumped - that really looks
>>> gross.
>>
>> Yes, that was the original plan -- but it has problems
>> 1) the dumper needs to know the root pass lists -- which can change
>> frequently -- it can be a long term maintanance burden;
>> 2) the centralized dumper needs to be done after option processing
>> 3) not sure if gate functions have any side effects or have dependencies on cfun
>>
>> The proposed solutions IMHO is not that intrusive -- just three hooks
>> to do the dumping and tracking indentation.
>
> Well, if you have a CU that is empty or optimized to nothing at some point
> you will not get a complete pass list.  I suppose optimize attributes might
> also confuse output.  Your solution might not be that intrusive
> but it is still ugly.  I don't see 1) as an issue, for 2) you can just call the
> dumping from toplev_main before calling do_compile (), 3) gate functions
> shouldn't have side-effects, but as they could gate on optimize_for_speed ()
> your option summary output will be bogus anyway.
>
> So - what is the output intended for if it isn't reliable?

This needs to be cleaned up at some point -- the gate function should
behave the same for all functions and per-function decisions need to
be pushed down to the executor body.  I will try to rework the patch
as you suggested to see if there are problems.

David


>
> Richard.
>
>>>
>>> The documentation should also link this option to the -fenable/disable
>>> options as obviously the pass names in that dump are those to be
>>> used for those flags (and not readily available anywhere else).
>>
>> Ok.
>>
>>>
>>> I also think that it would be way more useful to note in the individual
>>> dump files the functions (at the place they would usually appear) that
>>> have the pass explicitly enabled/disabled.
>>
>> Ok -- for ipa passes or tree/rtl passes where all functions are
>> explicitly disabled.
>>
>> Thanks,
>>
>> David
>>
>>>
>>> Richard.
>>>
>>>> Thanks,
>>>>
>>>> David
>>>>
>>>
>>
>