[Mesa-dev] [PATCH] i965/fs: Follow pow(16) instructions with a NOP.

[Francisco Jerez]

Matt Turner <mattst88 at gmail.com> writes:

> On Tue, May 3, 2016 at 3:28 PM, Francisco Jerez <currojerez at riseup.net> wrote:
>> Matt Turner <mattst88 at gmail.com> writes:
>>
>>> Beginning with commit 7b208a73, Unigine Valley began hanging the GPU on
>>> Gen >= 8 platforms. This patch avoids the GPU hangs, but does not
>>> implement a full work around for the restriction (dispatch_width == 16
>>> is an imperfect proxy).
>>>
>> Sounds like for a proper fix we could just check the last instruction in
>> the assembly at the top of the generator loop and emit a NOP in cases
>> where the previous instruction is one of the affected math opcodes?
>
> If I assume correctly that you mean "so we can check if the following
> instruction has two destination registers", then yes that would be
> good.
>
Yes, of course.

> What's the best way to check that?
> inst->dst.component_size(inst->exec_size) > REG_SIZE ?

Sounds reasonable to me. :)
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