[llvm-dev] TSAN hack on AArch64 for Android

[Dmitry Vyukov via llvm-dev]

On Tue, Aug 18, 2015 at 8:28 PM, Kostya Serebryany <kcc at google.com> wrote:
> +dvyukov
>
> On Mon, Aug 17, 2015 at 8:37 AM, Renato Golin <renato.golin at linaro.org>
> wrote:
>>
>> Folks,
>>
>> The review of patch http://reviews.llvm.org/D11532 is extremely slow
>> due to the number of hacks, left-overs and general undesired changes
>> and style that the submission has. That happens, and it's ok when the
>> overall direction the patch is going was agreed, and is acceptable as
>> generally good.
>>
>> But this is not the case.
>>
>> To wake up the elephant in the room, do we really think that adding
>> such a hack to an LLVM project for the sake of saving Android the
>> burden of carrying such hack is *acceptable*?

Hi Renato,

What exactly hack/hacks do you mean?



>> The only "reason" given to add such a hack was that, and I quote:
>>  * "what are we to do for NOW when the "proper" fix is maybe months
>> off, or possibly longer?"
>>  * "This patch will allow people to experiment with TSAN on their
>> android devices"
>>  * "don't let the perfect be the enemy of "limping along for a bit"
>>
>> So, in order to let *some* people *experiment* with TSAN on *Android*,
>> we're going to consciously make TSAN *limp along* for the foreseeable
>> future? Is that a wise price to pay for such a far fetched goal?
>>
>> The "proper" solution seems to be to fix TLS support, which:
>>  * "Ideally, this should be supported with the __thread keyword, but
>> that is not yet supported, and it is a much bigger chunk of work to
>> get it integrated into the default android cross compiler."
>>
>> So, to avoid a larger amount of work on another compiler, we're going
>> to cripple LLVM?
>>
>> I cannot see why this would *ever* be a wise decision... Please,
>> someone enlighten me.
>>
>> cheers,
>> --renato
>
>