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pan/bi: Lower phis to scalar 

If we don't lower phis to scalar, when we go out of SSA, we can get vector
nir_registers. In particular, we can get code like:

   r0 = vec2 r0.y, r0.x

This code looks like a move, but is in fact a swap. The trivial lowering of vec2
would not work -- the following fails to swap correctly:

   r0.x = r0.y
   r0.y = r0.x

Currently, we generate temporaries to handle these cases. It's easy to move the
complexity to NIR, though, and we'll want to scalarize phis for SSA-based RA
anyway.

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16585>
This commit is contained in:
Alyssa Rosenzweig 2022-05-18 09:42:41 -04:00 committed by Marge Bot
parent c8882ee115
commit 896dc63623
1 changed files with 1 additions and 0 deletions
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src/panfrost/bifrost/bifrost_compile.c
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@ -4256,6 +4256,7 @@ bi_optimize_nir(nir_shader *nir, unsigned gpu_id, bool is_blend)
}
NIR_PASS(progress, nir, nir_lower_alu_to_scalar, bi_scalarize_filter, NULL);
NIR_PASS(progress, nir, nir_lower_phis_to_scalar, true);
NIR_PASS(progress, nir, nir_opt_vectorize, bi_vectorize_filter, NULL);
NIR_PASS(progress, nir, nir_lower_bool_to_bitsize);