[Mesa-dev] [PATCH v2 1/4] nir: set default lod to texture opcodes that needed it but don't provide it

[Samuel Iglesias Gonsálvez]

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
---
 src/compiler/nir/nir_lower_tex.c | 68 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/src/compiler/nir/nir_lower_tex.c b/src/compiler/nir/nir_lower_tex.c
index 65681decb1c..d3380710405 100644
--- a/src/compiler/nir/nir_lower_tex.c
+++ b/src/compiler/nir/nir_lower_tex.c
@@ -717,6 +717,52 @@ linearize_srgb_result(nir_builder *b, nir_tex_instr *tex)
                                   result->parent_instr);
 }
 
+static void
+set_default_lod(nir_builder *b, nir_tex_instr *tex)
+{
+   b->cursor = nir_before_instr(&tex->instr);
+
+   /* We are going to emit the same texture but adding a default LOD.
+    */
+   int num_srcs = tex->num_srcs + 1;
+   nir_tex_instr *new = nir_tex_instr_create(b->shader, num_srcs);
+
+   new->op = tex->op;
+   new->sampler_dim = tex->sampler_dim;
+   new->texture_index = tex->texture_index;
+   new->dest_type = tex->dest_type;
+   new->is_array = tex->is_array;
+   new->is_shadow = tex->is_shadow;
+   new->is_new_style_shadow = tex->is_new_style_shadow;
+   new->sampler_index = tex->sampler_index;
+   new->texture = nir_deref_var_clone(tex->texture, new);
+   new->sampler = nir_deref_var_clone(tex->sampler, new);
+   new->coord_components = tex->coord_components;
+
+   nir_ssa_dest_init(&new->instr, &new->dest, 4, 32, NULL);
+
+   int src_num = 0;
+   for (int i = 0; i < tex->num_srcs; i++) {
+      nir_src_copy(&new->src[src_num].src, &tex->src[i].src, new);
+      new->src[src_num].src_type = tex->src[i].src_type;
+      src_num++;
+   }
+
+   new->src[src_num].src = nir_src_for_ssa(nir_imm_int(b, 0));
+   new->src[src_num].src_type = nir_tex_src_lod;
+   src_num++;
+
+   assert(src_num == num_srcs);
+
+   nir_ssa_dest_init(&new->instr, &new->dest,
+                     tex->dest.ssa.num_components, 32, NULL);
+   nir_builder_instr_insert(b, &new->instr);
+
+   nir_ssa_def_rewrite_uses(&tex->dest.ssa, nir_src_for_ssa(&new->dest.ssa));
+
+   nir_instr_remove(&tex->instr);
+}
+
 static bool
 nir_lower_tex_block(nir_block *block, nir_builder *b,
                     const nir_lower_tex_options *options)
@@ -813,6 +859,28 @@ nir_lower_tex_block(nir_block *block, nir_builder *b,
          progress = true;
          continue;
       }
+
+      /* 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 (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->stage != MESA_SHADER_FRAGMENT)) {
+         int i;
+         bool has_lod = false;
+         for (i = 0; i < tex->num_srcs; i++) {
+            if (tex->src[i].src_type == nir_tex_src_lod) {
+               has_lod = true;
+               break;
+            }
+         }
+
+         if (!has_lod) {
+            set_default_lod(b, tex);
+            progress = true;
+            continue;
+         }
+      }
    }
 
    return progress;
-- 
2.14.2