Another problem with "Recommit r265547, and r265610,r265639,r265657"

[Mikael Holmén via llvm-commits]

Hi Wei,

On 05/09/2016 05:44 PM, Wei Mi wrote:
>>> Instruction with a tied operand is not triviallyRematerializable so
>>> the problem shouldn't appear either. If that problem still exists with
>>> your patch in RegisterCoalescer, we need to look deeply into what is
>>> wrong there to come up a better fix.
>>
>>
>> The problem still exists if only using my fix in RegisterCoalescer.
>>
>> However, if applying your patch http://reviews.llvm.org/D19486 it goes away.
>> Do you intend to push that?
>>
>> For a while I thought your patch wouldn't be necessary with the
>> RegisterCoalescer change, but maybe it is for the tied-operand case then?
>>
>> Thanks,
>> Mikael
>>
>
> I plan to push http://reviews.llvm.org/D19486 but change the
> triviallyRematerializable condition to an assertion, i.e., I expect no
> instruction entering DeadRemat will be non-triviallyRematerializable.
>
> For the tied-operand case, could you send me a debug trace like you
> sent last time, I can look at how a non-triviallyRematerializable inst
> makes its way to DeadRemat.

For sure!

I attached a run when it crashed with -debug -print-before-all 
-print-after-all. I also added a few printouts of my own. Note that this 
is run with -O3, not -O0 which I used to see the other problem.

Hope you can make something out of it.

Thanks,
Mikael

>
> Thanks,
> Wei.
>
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