v3d/tex: use TMUSLOD register if possible

TMUSLOD register is the same that TMUS but having the same effect that
setting disable_autolod on the TMU configuration parameter 2.

So using that register is potentially more efficient, as in several
cases we would be able to skip writing P2.

One case where we can't use it is for texture cube maps, as we need to
use TMUSCM.

v2: don't put a comment in the middle of the conditions (Iago)

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4962>

diff --git a/src/broadcom/compiler/v3d40_tex.c b/src/broadcom/compiler/v3d40_tex.c
index 2996313e518ebce5060b86596c587cfef5439a98..7af14baf12722200ef45d417297573359f4911ad 100644 (file)
--- a/src/broadcom/compiler/v3d40_tex.c
+++ b/src/broadcom/compiler/v3d40_tex.c
@@ -123,8 +123,15 @@ v3d40_vir_emit_tex(struct v3d_compile *c, nir_tex_instr *instr)
                                       ntq_get_src(c, instr->src[i].src, 0),
                                       &tmu_writes);
 
-                        if (instr->op != nir_texop_txf)
+                        /* With texel fetch automatic LOD is already disabled,
+                         * and disable_autolod must not be enabled. For
+                         * non-cubes we can use the register TMUSLOD, that
+                         * implicitly sets disable_autolod.
+                         */
+                        if (instr->op != nir_texop_txf &&
+                            instr->sampler_dim == GLSL_SAMPLER_DIM_CUBE) {
                                 p2_unpacked.disable_autolod = true;
+                        }
                         break;
 
                 case nir_tex_src_comparator:
@@ -267,6 +274,8 @@ v3d40_vir_emit_tex(struct v3d_compile *c, nir_tex_instr *instr)
                 vir_TMU_WRITE(c, V3D_QPU_WADDR_TMUSF, s, &tmu_writes);
         } else if (instr->sampler_dim == GLSL_SAMPLER_DIM_CUBE) {
                 vir_TMU_WRITE(c, V3D_QPU_WADDR_TMUSCM, s, &tmu_writes);
+        } else if (instr->op == nir_texop_txl) {
+                vir_TMU_WRITE(c, V3D_QPU_WADDR_TMUSLOD, s, &tmu_writes);
         } else {
                 vir_TMU_WRITE(c, V3D_QPU_WADDR_TMUS, s, &tmu_writes);
         }