Re: [RFC][PATCH] Introduce -fdump*-folding

["Martin Liška" <mliska@suse.cz>]

On 05/09/2017 02:16 PM, Richard Biener wrote:
> On Tue, May 9, 2017 at 2:01 PM, Martin Liška <mliska@suse.cz> wrote:
>> On 05/05/2017 01:50 PM, Richard Biener wrote:
>>> On Thu, May 4, 2017 at 1:10 PM, Martin Liška <mliska@suse.cz> wrote:
>>>> On 05/04/2017 12:40 PM, Richard Biener wrote:
>>>>>
>>>>> On Thu, May 4, 2017 at 11:22 AM, Martin Liška <mliska@suse.cz> wrote:
>>>>>>
>>>>>> On 05/03/2017 12:12 PM, Richard Biener wrote:
>>>>>>>
>>>>>>>
>>>>>>> On Wed, May 3, 2017 at 10:10 AM, Martin Liška <mliska@suse.cz> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> Hello
>>>>>>>>
>>>>>>>> Last release cycle I spent quite some time with reading of IVOPTS pass
>>>>>>>> dump file. Using -fdump*-details causes to generate a lot of 'Applying
>>>>>>>> pattern'
>>>>>>>> lines, which can make reading of a dump file more complicated.
>>>>>>>>
>>>>>>>> There are stats for tramp3d with -O2 and -fdump-tree-all-details.
>>>>>>>> Percentage number
>>>>>>>> shows how many lines are of the aforementioned pattern:
>>>>>>>>
>>>>>>>>                         tramp3d-v4.cpp.164t.ivopts: 6.34%
>>>>>>>>                           tramp3d-v4.cpp.091t.ccp2: 5.04%
>>>>>>>>                       tramp3d-v4.cpp.093t.cunrolli: 4.41%
>>>>>>>>                       tramp3d-v4.cpp.129t.laddress: 3.70%
>>>>>>>>                           tramp3d-v4.cpp.032t.ccp1: 2.31%
>>>>>>>>                           tramp3d-v4.cpp.038t.evrp: 1.90%
>>>>>>>>                      tramp3d-v4.cpp.033t.forwprop1: 1.74%
>>>>>>>>                           tramp3d-v4.cpp.103t.vrp1: 1.52%
>>>>>>>>                      tramp3d-v4.cpp.124t.forwprop3: 1.31%
>>>>>>>>                           tramp3d-v4.cpp.181t.vrp2: 1.30%
>>>>>>>>                        tramp3d-v4.cpp.161t.cunroll: 1.22%
>>>>>>>>                     tramp3d-v4.cpp.027t.fixup_cfg3: 1.11%
>>>>>>>>                        tramp3d-v4.cpp.153t.ivcanon: 1.07%
>>>>>>>>                           tramp3d-v4.cpp.126t.ccp3: 0.96%
>>>>>>>>                           tramp3d-v4.cpp.143t.sccp: 0.91%
>>>>>>>>                      tramp3d-v4.cpp.185t.forwprop4: 0.82%
>>>>>>>>                            tramp3d-v4.cpp.011t.cfg: 0.74%
>>>>>>>>                      tramp3d-v4.cpp.096t.forwprop2: 0.50%
>>>>>>>>                     tramp3d-v4.cpp.019t.fixup_cfg1: 0.37%
>>>>>>>>                      tramp3d-v4.cpp.120t.phicprop1: 0.33%
>>>>>>>>                            tramp3d-v4.cpp.133t.pre: 0.32%
>>>>>>>>                      tramp3d-v4.cpp.182t.phicprop2: 0.27%
>>>>>>>>                     tramp3d-v4.cpp.170t.veclower21: 0.25%
>>>>>>>>                        tramp3d-v4.cpp.029t.einline: 0.24%
>>>>>>>>
>>>>>>>> I'm suggesting to add new TDF that will be allocated for that.
>>>>>>>> Patch can bootstrap on ppc64le-redhat-linux and survives regression
>>>>>>>> tests.
>>>>>>>>
>>>>>>>> Thoughts?
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Ok.  Soon we'll want to change dump_flags to uint64_t ...  (we have 1
>>>>>>> bit
>>>>>>> left
>>>>>>> if you allow negative dump_flags).  It'll tickle down on a lot of
>>>>>>> interfaces
>>>>>>> so introducing dump_flags_t at the same time might be a good idea.
>>>>>>
>>>>>>
>>>>>>
>>>>>> Hello.
>>>>>>
>>>>>> I've prepared patch that migrates all interfaces and introduces
>>>>>> dump_flags_t.
>>>>>
>>>>>
>>>>> Great.
>>>>>
>>>>>> I've been
>>>>>> currently testing that. Apart from that Richi requested to come up with
>>>>>> more
>>>>>> generic approach
>>>>>> of hierarchical structure of options.
>>>>>
>>>>>
>>>>> Didn't really "request" it, it's just something we eventually need to do
>>>>> when
>>>>> we run out of bits again ;)
>>>>
>>>>
>>>> I know, but it was me who came up with the idea of more fine suboptions :)
>>>>
>>>>>
>>>>>>
>>>>>> Can you please take a look at self-contained source file that shows way
>>>>>> I've
>>>>>> decided to go?
>>>>>> Another question is whether we want to implement also "aliases", where
>>>>>> for
>>>>>> instance
>>>>>> current 'all' is equal to union of couple of suboptions?
>>>>>
>>>>>
>>>>> Yeah, I think we do want -all-all-all and -foo-all to work.  Not sure
>>>>> about -all-foo-all.
>>>>
>>>>
>>>> Actually only having 'all' is quite easy to implement.
>>>>
>>>> Let's imagine following hierarchy:
>>>>
>>>> (root)
>>>> - vops
>>>> - folding
>>>>   - gimple
>>>>     - ctor
>>>>     - array_ref
>>>>     - arithmetic
>>>>   - generic
>>>>     - c
>>>>     - c++
>>>>     - ctor
>>>>     - xyz
>>>>
>>>> Then '-fdump-passname-folding-all' will be equal to
>>>> '-fdump-passname-folding'.
>>>
>>> Ok, so you envision that sub-options restrict stuff.  I thought of
>>>
>>>  -gimple
>>>    -vops
>>>  -generic
>>>    -folding
>>>
>>> so the other way around.  We do not have many options that would be RTL
>>> specific but gimple only are -vops -alias -scev -gimple -rhs-only
>>> -verbose -memsyms
>>> while RTL has -cselib. -eh sounds gimple specific.  Then there's the optgroup
>>> stuff you already saw.
>>>
>>> So it looks like a 8 bit "group id" plus 56 bits of flags would do.
>>>
>>> Yes, this implies reworking how & and | work.  For example you can't
>>> | dump-flags of different groups.
>>
>> Well, I'm not opposed to idea of converting that to way you described.
>> So, you're willing to introduce something like:
>>
>> (root)
>> - generic
>>   - eh
>>   - folding
>>   - ...
>> - gimple
>>   - vops
>>   - folding
>>    - rhs-only
>>    - ...
>>   - vops
>> - rtl
>>   - cselib
>>   - ...
>>
>> ?
> 
> Yeah.  As said the motivation was to escape the 32 (now 64) bits limitation,
> not to make the user interface into a hierarchy.
> 
> I suppose we can easily defer now given we have 32 bits available now ;)

I see. Hopefully we can live quite some time with another 32 bits and I'm going
to transform the TDF_* stuff to enum.

Martin

> 
> Richard.
> 
>>>
>>>>>
>>>>> The important thing is to make sure dump_flags_t stays POD and thus is
>>>>> eligible to be passed in register(s).  In the end we might simply come up
>>>>> with a two-level hierarchy, each 32bits (or we can even get back to 32bits
>>>>> in total with two times 16bits).
>>>>
>>>>
>>>> I'm aware of having the type as POD.
>>>>
>>>>>
>>>>> It looks you didn't actually implement this as a hierarchy though but
>>>>> still allocate from one pool of bits (so you only do a change to how
>>>>> users access this?)
>>>>
>>>>
>>>> Yep, all leaf options are mapped to a mask and all inner nodes are just
>>>> union
>>>> of suboptions. That will allow us to have 64 leaf suboptions. Reaching the
>>>> limit
>>>> we can encode the values in more sophisticated way. That however brings need
>>>> to implement more complicated '&' and '|' operators.
>>>>
>>>> I'll finish the implementation and try to migrate that to current handling.
>>>> Guess, I'm quite close.
>>>
>>> Hmm, but then there's not much advantage in suboptions (well, apart from maybe
>>> at the user-side).
>>
>> Yep, please take a look at updated version of PATCH 2/N, where I ported -fopt-info.
>> As you can see I had to explicitly define all enum values and hierarchy creation
>> of every single node.
>>
>> Martin
>>
>>>
>>>> Martin
>>>>
>>>>
>>>>>
>>>>> Thanks,
>>>>> Richard.
>>>>>
>>>>>>
>>>>>> Thanks for feedback,
>>>>>> Martin
>>>>>>
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Richard.
>>>>>>>
>>>>>>>> Martin
>>>>>>
>>>>>>
>>>>>>
>>>>
>>