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

[Richard Guenther <richard.guenther@gmail.com>]

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?

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
>>>
>>
>