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

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

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.

+  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.

+  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).

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.

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
>>>>>>
>>>>>
>>>>
>>>
>>
>