Alyssa Rosenzweig 261d48fc9b pan/mdg: Refuse to schedule CSEL.vector to SMUL
Even if we only mask a single component from the result of CSEL.vector,
in our IR we treat its semantics as vector which causes trouble with
when scheduled to a scalar unit.

The problematic bundle looks like this:

   vmul.MOV.i32 R31, TMP0.xxxx, R0.yzww
   sadd.MAX.i32 TMP0.y, R0.y, #65408
   smul.CSEL.vector.i32 R0.y, TMP0.y, #127

As the comment in midgard.h illuminates, these CSEL instructions are
actually operating per-bit, lining up with the all-1's booleans in
Midgard. The Bifrost analogue is MUX.i32.bit, not CSEL.i32. We should
probably rename the Midgard instruction to make that clear.

Anyhoo, on the scalar unit, CSEL/MUX operates on the bottom 32-bits of
its source. That's ok for the usual r31.w case, because that's secretly
replicating to its nonexistent register, I think? But that doesn't work
with the CSEL.vector (MUX.vector) form, because the condition it's
actually muxing on is r31.x, which here is R0.y, not the intended R0.x.

Rather than adding more special cases to the already overcomplicated
scheduler (for the dubious benefit of avoiding a small shaderdb
regression), just avoid scheduling CSEL.vector to smul.

With the next patch, fixes:

dEQP-GLES31.functional.draw_buffers_indexed.random.max_required_draw_buffers.1

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19763>
2022-12-01 00:52:53 +00:00
2022-11-22 19:04:13 +00:00
2022-10-20 22:52:06 +00:00
2022-01-19 15:17:17 +00:00
2022-11-21 23:09:30 +00:00

`Mesa <https://mesa3d.org>`_ - The 3D Graphics Library
======================================================


Source
------

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---------------

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