[Bug 93840] [i965] Compiler backend uses too much stack with Alien: Isolation

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=93840

--- Comment #37 from Darius Spitznagel <d.spitznagel at goodbytez.de> ---
(In reply to Eero Tamminen from comment #36)
> (In reply to _archuser_ from comment #34)
> > by disabling the shader prewarmer in
> > ~/.local/share/feral-interactive/AlienIsolation/preferences
> > (EnableShaderWarmer / EnableShaderWarmerPredraw = 0) the game starts and is
> > playable (very fast load times, bad hickups as in game shaders are compiled
> > on the fly?)
> > The prewarmer seems to compile all shaders for the game in one go, maybe
> > that is a reason for such a huge running shader program ?
> 
> By using those options, the game starts very quickly on SKL too, and there
> are no crashes during startup or short gameplay (just more stuttering during
> actual gameplay due to on-demand shader compilation).
> 
> As it starts fine without dummy version of pthread_attr_setstacksize(), 
> none of those mega compute shaders is needed / used during startup or early
> gameplay.
> 
> I wonder at which place in the game they're actually used...

Good news:)
But the real question is, how this problem can be solved in the manner of "out
of the box experience" on intel i965?
I don't know if feral is using a shaderwarmer for more games. The ones I have
beside Alien: Isolation work without any "tricks".

Maybe Alex Smith from feral who is involved in radv development could give more
insight?
It would be interesting to know if the shaderwarmer is also a problem for other
mesa drivers like radeon, radeonsi, nouveau...?

This report is now over 1 year old and thanks to _archuser_ there is now a
workaround for intel.

I'am happy that I can compile new versions of Mesa now without Matts patch as
it seems it will never go upstream and does not work with Skylake.

For me this report/issue can be closed, but I would of cource prefer an "out of
the box experience" solution for intel users.
There is definitely somewhere a problem with huge/massive shaderprograms (maybe
simply a misbehavior) on i965.

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