-fdump-passes -fenable-xxx=func_name_list

Xinliang David Li davidxl@google.com
Mon Jun 6 16:00:00 GMT 2011


On Mon, Jun 6, 2011 at 4:38 AM, Richard Guenther
<richard.guenther@gmail.com> wrote:
> On Thu, Jun 2, 2011 at 9:12 AM, Xinliang David Li <davidxl@google.com> wrote:
>> This is the version of the patch that walks through pass lists.
>>
>> Ok with this one?
>
> +/* Dump all optimization passes.  */
> +
> +void
> +dump_passes (void)
> +{
> +  struct cgraph_node *n, *node = NULL;
> +  tree save_fndecl = current_function_decl;
> +
> +  fprintf (stderr, "MAX_UID = %d\n", cgraph_max_uid);
>
> this isn't accurate info - cloning can cause more cgraph nodes to
> appear (it also looks completely unrelated to dump_passes ...).
> Please drop it.

Ok.


>
> +  create_pass_tab();
> +  gcc_assert (pass_tab);
>
> you have quite many asserts of this kind - we don't want them when
> the previous stmt as in this case indicates everything is ok.

ok.

>
> +  push_cfun (DECL_STRUCT_FUNCTION (node->decl));
>
> this has side-effects, I'm not sure we want this here.  Why do you
> need it?  Probably because of
>
> +  is_really_on = override_gate_status (pass, current_function_decl, is_on);
>
> ?  But that is dependent on the function given which should have no
> effect (unless it is overridden globally in which case override_gate_status
> and friends should deal with a NULL cfun).

As we discussed, currently some pass gate functions depend on per node
information -- those checks need to be pushed into execute functions.
I would like to clean those up later -- at which time, the push/pop
can be removed.

>
> I don't understand why you need another table mapping pass to name
> when pass->name is available and the info is trivially re-constructible.

This is needed as the pass->name is not the canonicalized name (i.e.,
not with number suffix etc), so the extra mapping from id to
normalized name is needed.

Thanks,

David

>
> Thanks,
> Richard.
>
>> David
>>
>> On Wed, Jun 1, 2011 at 12:45 PM, Xinliang David Li <davidxl@google.com> wrote:
>>> 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
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>



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