Mesa (master): nir: Don't set LOD=0 for compute shader that has derivative group

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Module: Mesa
Branch: master
Commit: fcbc5ccaae6e606e68199c838e23545b4283b788
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=fcbc5ccaae6e606e68199c838e23545b4283b788

Author: Caio Marcelo de Oliveira Filho <caio.oliveira at intel.com>
Date:   Fri Apr  5 16:04:40 2019 -0700

nir: Don't set LOD=0 for compute shader that has derivative group

When using NV_compute_shader_derivatives to set a derivative group,
a compute shader supports texture with implicit LOD calculation, so
don't set an explicit LOD.

Note if the extension is used but the derivative group is not
specified, it will default to LOD=0 as before.

Reviewed-by: Jason Ekstrand <jason at jlekstrand.net>

---

 src/compiler/nir/nir_lower_tex.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/src/compiler/nir/nir_lower_tex.c b/src/compiler/nir/nir_lower_tex.c
index eee1b3105d5..54db7b761cb 100644
--- a/src/compiler/nir/nir_lower_tex.c
+++ b/src/compiler/nir/nir_lower_tex.c
@@ -1111,14 +1111,18 @@ nir_lower_tex_block(nir_block *block, nir_builder *b,
          continue;
       }
 
+      bool shader_supports_implicit_lod =
+         b->shader->info.stage == MESA_SHADER_FRAGMENT ||
+         (b->shader->info.stage == MESA_SHADER_COMPUTE &&
+          b->shader->info.cs.derivative_group != DERIVATIVE_GROUP_NONE);
+
       /* TXF, TXS and TXL require a LOD but not everything we implement using those
        * three opcodes provides one.  Provide a default LOD of 0.
        */
       if ((nir_tex_instr_src_index(tex, nir_tex_src_lod) == -1) &&
           (tex->op == nir_texop_txf || tex->op == nir_texop_txs ||
            tex->op == nir_texop_txl || tex->op == nir_texop_query_levels ||
-           (tex->op == nir_texop_tex &&
-            b->shader->info.stage != MESA_SHADER_FRAGMENT))) {
+           (tex->op == nir_texop_tex && !shader_supports_implicit_lod))) {
          b->cursor = nir_before_instr(&tex->instr);
          nir_tex_instr_add_src(tex, nir_tex_src_lod, nir_src_for_ssa(nir_imm_int(b, 0)));
          progress = true;