[PATCH] D15537: limit the number of instructions per block examined by dead store elimination

[Xinliang David Li via llvm-commits]

On Thu, Aug 25, 2016 at 9:50 AM, Daniel Berlin <dberlin at dberlin.org> wrote:
> If folks are willing to actually commit to fixing this on a near-term
> timeline (and it sounds like the answer was "yes"), i'm okay with this
> patch.
>

Yes, moving DSE to MemorySSA will be one of the near term item I plan to push.

David


> If i've got that wrong, we really should explore other solutions (like
> caching).
>
>
> On Tue, Aug 23, 2016 at 4:47 PM, Philip Reames <listmail at philipreames.com>
> wrote:
>>
>> FYI, I'm going to defer to Danny on the choice to move forward with this
>> patch or an alternate.  I feel he's in the best position to assess the
>> overall timeline for MemorySSA.
>>
>>
>> On 08/23/2016 01:35 PM, Xinliang David Li wrote:
>>>
>>> On Tue, Aug 23, 2016 at 1:20 PM, Daniel Berlin <dberlin at dberlin.org>
>>> wrote:
>>>>>
>>>>> While implementing caching is possible, I think we should avoid
>>>>> reinventing the wheel in memorySSA, but to keep the fix as simple as
>>>>> possible.  The new limit can be adjusted higher as its meaning has
>>>>> changed.
>>>>
>>>>
>>>> I'd be more okay with your last argument if you were going to commit to
>>>> rewriting this pass to MemorySSA.
>>>> :)
>>>
>>> Definitely committed -- no question about it :)  I don't think we have
>>> any choice actually, but patches like this do allow buy us more time
>>> to do so.
>>>
>>>
>>>> If we have no-one committed to moving the pass, and no plans to
>>>> implement
>>>> caching, i guess my answer is "hope that someone will move this to
>>>> MemorySSA
>>>> one day is not a strategy".
>>>
>>> that is right.
>>>
>>> For this patch, I considered it high priority because there are so
>>> many people got hit by the same issue again and again. The most recent
>>> clang hanging problem in building chromium is a recent example.
>>>
>>> David
>>>
>>>>
>>
>