[Bug 93840] [i965] Alien: Isolation fails with GL_ARB_compute_shader enabled

[bugzilla-daemon at freedesktop.org]

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

Matt Turner <mattst88 at gmail.com> changed:

           What    |Removed                     |Added
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                 CC|                            |mattst88 at gmail.com

--- Comment #14 from Matt Turner <mattst88 at gmail.com> ---
Created attachment 126122
  --> https://bugs.freedesktop.org/attachment.cgi?id=126122&action=edit
patch

(In reply to Darius Spitznagel from comment #1)
> Created attachment 121746 [details]
> Alien: Isolation GDB log

The memset() at line 935 of
a4cff18:src/mesa/drivers/dri/i965/brw_schedule_instructions.cpp is

>   memset(last_grf_write, 0, sizeof(last_grf_write));

The backtrace shows

#1  0x00007fffe79015fe in memset (__len=482688, __ch=0, __dest=0x7fffa216e550)
at /usr/include/x86_64-linux-gnu/bits/string3.h:84

__len=482688?!

last_grf_write is sized as

>   schedule_node *last_grf_write[grf_count * 16];

and 482688 / 16 is 30168. So we have 30168 virtual registers?!

I would very much like to see this shader... could you try to capture it with
MESA_SHADER_CAPTURE_PATH=/tmp/alienisolation [...] (after making that
directory)? It will write shaders to the directory, and I would expect the last
one it writes to be the one causing the trouble. :)



I expect the attached patch will fix it, though I'm not sure it's exactly what
we want to do. (Of course capture the shaders without this patch)

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