[llvm-commits] [LLVMdev] [PATCH] Refactoring the DFA generator

[Ivan Llopard]

Hi Anshu,

I don't have commit access. It applies correctly on trunk, I've just 
checked it. Could you please commit it?

Ivan

On 26/06/2012 04:44, adasgupt at codeaurora.org wrote:
> Hi Ivan,
>
> Sorry, I should have been more explicit in my last email. The patch looks
> good to me. Please check that it applies on trunk and go ahead and commit.
>
> Thanks
> -Anshu
>
>
>
>> Hi Anshu,
>>
>> Just in case you have forgotten this thread ;-). Is this patch ok to
>> commit or does it not apply to trunk properly ?
>> I can fix it if that's the problem.
>>
>> Ivan
>>
>> On 20/06/2012 19:33, Anshuman Dasgupta wrote:
>>>> Thanks for reviewing this. I added a top comment for AddInsnClass
>>> and I fixed the violation of column numbers.
>>>
>>> Great. Looks good to me.
>>>
>>>> IMO, it wil be nice to keep it alive for performance comparisons.
>>> Given the overall performance
>>>> is rather determined by transition searches on the current state,
>>> for small DFA tables may not be a win
>>>> and it may still be the case for greater ones.
>>> I agree; let's keep it around for now.
>>>
>>> -Anshu
>>>
>>> ---
>>> Qualcomm Innovation Center, Inc is a member of the Code Aurora Forum
>>>
>>>
>>>
>>> On 6/18/2012 3:47 AM, Ivan Llopard wrote:
>>>> Hi Anshu,
>>>>
>>>> Thanks for reviewing this. I added a top comment for AddInsnClass and
>>>> I fixed the violation of column numbers.
>>>>
>>>> On 15/06/2012 21:31, Anshuman Dasgupta wrote:
>>>>> Hi Ivan,
>>>>>
>>>>> The patch looks good to me. I have a couple of minor comments:
>>>>>
>>>>> +void State::AddInsnClass(unsigned InsnClass,
>>>>> Add a top level comment describing the function
>>>>>
>>>>> +  std::map<State*, std::set<Transition*, ltTransition>, ltState>
>>>>> stateTransitions;
>>>>> You should be able to use SmallSet here. Also, this line exceeds 80
>>>>> columns.
>>>> I tried but SmallSet is not iterable. SmallSetPtr could be useful
>>>> here but it doesn't allow custom sorting.
>>>>
>>>>>
>>>>> On a related note, is the CachedTable mechanism in DFAPacketizer.h
>>>>> useful for your architecture? Currently the DFA generator generates
>>>>> one table for a given architecture. I had originally added the
>>>>> CachedTable mechanism since for a given compilation and subtarget,
>>>>> the DFA only uses the subset of the states and transitions. Using a
>>>>> "cache" made sense. At one point, I'd like to change the code so
>>>>> that it can generate one DFA for every subtarget and remove the
>>>>> CachedTable mechanism. Given the size of the DFA for your
>>>>> architecture, however, it may make sense to keep it around even if
>>>>> it generates separate tables for each subtarget.
>>>> I liked the cachedtable idea but I can't tell you if it's really
>>>> useful in our case, I didn't make any performance tests in that regard.
>>>> IMO, it wil be nice to keep it alive for performance comparisons.
>>>> Given the overall performance is rather determined by transition
>>>> searches on the current state, for small DFA tables may not be a win
>>>> and it may still be the case for greater ones. We have a huge number
>>>> of states but the number of distinct itineraries, or maximum possible
>>>> transitions, remains quite small (11, it wasn't 13, my mistake).
>>>>
>>>> Ivan
>>>>
>>>>> Thanks
>>>>> -Anshu
>>>>>
>>>>> ---
>>>>> Qualcomm Innovation Center, Inc is a member of the Code Aurora Forum
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> On 6/14/2012 8:22 AM, Ivan Llopard wrote:
>>>>>> Hi,
>>>>>>
>>>>>> I've refactored the DFA generator in TableGen because it takes too
>>>>>> much time to build the table of our BE and I'd like to share it.
>>>>>> We have 15 functional units and 13 different itineraries which, in
>>>>>> the worst case, can produce 13! states. Fortunately, many of those
>>>>>> states are reused :-) but it still takes up to 11min to build the
>>>>>> entire table. This patch reduces the build time to 5min, giving a
>>>>>> speed-up factor greater than 2.
>>>>>>
>>>>>> It contains small changes:
>>>>>> - Transitions are stored in a set for quicker searches
>>>>>> - canAddInsnClass() API is split in two API's:
>>>>>>    - canAddInsnClass() which perform a quick verification about the
>>>>>> possibility of having new states for a given InsnClass
>>>>>>    - AddInsnClass() performs the actual computation of possible
>>>>>> states.
>>>>>>
>>>>>> I've regenerated the DFA table of Hexagon and all seems to be ok.
>>>>>>
>>>>>> What do you think about these changes ?
>>>>>>
>>>>>>
>>>>>> Ivan
>>>>>>
>>>>>>
>>>>>> _______________________________________________
>>>>>> llvm-commits mailing list
>>>>>> llvm-commits at cs.uiuc.edu
>>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>>>>
>>>
>