On Wed, Apr 26, 2017 at 3:01 PM, Bin.Cheng <amker.ch...@gmail.com> wrote:
> On Wed, Apr 26, 2017 at 2:27 PM, Richard Biener
> <richard.guent...@gmail.com> wrote:
>> On Tue, Apr 18, 2017 at 12:51 PM, Bin Cheng <bin.ch...@arm.com> wrote:
>>> Hi,
>>> This patch adds new loop constraint flags marking prologue, epilogue and
>>> versioned loops generated
>>> by vectorizer, unroller and versioning. These flags will be used in IVOPTs
>>> in order to differentiate
>>> possible hot innermost loop from others. I also plan to use them to avoid
>>> unnecessary cunroll on
>>> such loops.
>>> Is it OK?
>>
>> Hmm, it doesn't really match "constraints".
>>
>> I'd rather somehow track the "original" loop it was versioned / copied
>> from plus either a
>> "kind" (epilogue, prologue, version) or determine this from dominance
>> relationship between
>> the copy and the original loop.
> Or we generalize "constraints flags", saying to introduce general
> bit-wise flags for loop structure. Among these flags, one kind is
> constraint flags, the rest are general flags. We could also change
> boolean fields into such flags?
> I do have following patches relying on this to avoid complete unroll
> for prologue/epilogue loops.
>>
>> Thus,
>>
>> struct loop {
>> ...
>> /* If not zero the loop number this loop was copied from. */
>> unsigned clone_of;
> In this case, we need to track between different loops, which looks
> like a burden. For example, we need to make sure loop number won't be
> reused. Even more complicated, considering in extreme case that the
> original loop could be removed.
>
I will drop this one from this patch series.
Thanks,
bin
>>
>> would that help? With knowing loop relation we can also more
>> aggressively version
>> and eventually later collapse the two versions again if we can still
>> identify them and
>> they are still reasonably similar.
>>
>> Richard.
>>
>>>
>>> Thanks,
>>> bin
>>> 2017-04-11 Bin Cheng <bin.ch...@arm.com>
>>>
>>> * cfgloop.h (LOOP_C_PROLOG, LOOP_C_EPILOG, LOOP_C_VERSION): New.
>>> * tree-ssa-loop-manip.c (tree_transform_and_unroll_loop): Set
>>> LOOP_C_EPILOG for unrolled epilogue loop.
>>> (vect_do_peeling): Set LOOP_C_PROLOG and LOOP_C_EPILOG for peeled
>>> loops.
>>> (vect_loop_versioning): Set LOOP_C_VERSION for versioned loop.
