Re: [PATCH] Fix for PR64081 in RTL loop unroller

[Jeff Law <law@redhat.com>]

On 01/15/15 09:36, Zamyatin, Igor wrote:
>>
>> On 01/13/15 11:01, Zamyatin, Igor wrote:
>>>>
>>>> Is it really sufficient here to verify that all the defs are on latch
>>>> predecessors, what about the case where there is a predecessor
>>>> without a def.  How do you guarantee domination in that case?
>>>>
>>>> ISTM that given the structure for the code you're writing that you'd
>>>> want to verify that in the event of multiple definitions that all of
>>>> them appear on immediate predecessors of the latch *and* that each
>>>> immediate predecessor has a definition.
>>>
>>> Yes, do you think it's better to check exactly immediate predecessors?
>> I'd use the same structure that you have in iv_get_reaching_def.  If there
>> was a reasonable way to factor that test into a single function and call it from
>> both places that would be even better.
>
> Not sure it's possible to merge DF_REG_DEF_CHAIN walk and DF_REF_CHAIN walk...
OK.  Just use the same overall structure if we can't pull the test out 
into a single function that could be called from both places.

jeff