Mesa (main): nir_to_tgsi: Don't vectorize 64-bit instructions, to keep virgl happy.

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Module: Mesa
Branch: main
Commit: eaf6e3d3af62b231499bde49ad879d22d0825bff
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=eaf6e3d3af62b231499bde49ad879d22d0825bff

Author: Emma Anholt <emma at anholt.net>
Date:   Fri Oct  8 11:51:48 2021 -0700

nir_to_tgsi: Don't vectorize 64-bit instructions, to keep virgl happy.

virglrenderer makes invalid shaders when faced with vector 64-bit
instructions, which GLSL-to-TGSI never produced.  While this doesn't fix
everything, it does get more tests running, and virgl probably the primary
consumer of 64-bit TGSI.  virgl may be deprecating its host 64-bit
support, at which point we can drop this workaround.

Reviewed-by: Gert Wollny <gert.wollny at collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15014>

---

 src/gallium/auxiliary/nir/nir_to_tgsi.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/gallium/auxiliary/nir/nir_to_tgsi.c b/src/gallium/auxiliary/nir/nir_to_tgsi.c
index 2d00e5cc5db..b55ca318efe 100644
--- a/src/gallium/auxiliary/nir/nir_to_tgsi.c
+++ b/src/gallium/auxiliary/nir/nir_to_tgsi.c
@@ -2990,14 +2990,18 @@ ntt_should_vectorize_instr(const nir_instr *instr, void *data)
       break;
    }
 
-   unsigned num_components = alu->dest.dest.ssa.num_components;
-
    int src_bit_size = nir_src_bit_size(alu->src[0].src);
    int dst_bit_size = nir_dest_bit_size(alu->dest.dest);
 
    if (src_bit_size == 64 || dst_bit_size == 64) {
-      if (num_components > 1)
-         return false;
+      /* Avoid vectorizing 64-bit instructions at all.  Despite tgsi.rst
+       * claiming support, virglrenderer generates bad shaders on the host when
+       * presented with them.  Maybe we can make virgl avoid tickling the
+       * virglrenderer bugs, but given that glsl-to-TGSI didn't generate vector
+       * 64-bit instrs in the first place, I don't see much reason to care about
+       * this.
+       */
+      return false;
    }
 
    return true;