spirv, compiler: add "bool nv" to shader_info.mesh

Not knowing whether we deal with the NV or EXT extension
makes implementation difficult for Intel HW.
NV support will be dropped at some point, so
this ugliness will go away eventually.

Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Jason Ekstrand <jason.ekstrand@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18366>

src/compiler/shader_info.h

@@ -540,6 +540,9 @@ typedef struct shader_info {
          uint16_t max_vertices_out;
          uint16_t max_primitives_out;
          uint16_t primitive_type;  /* GL_POINTS, GL_LINES or GL_TRIANGLES. */
+
+         /* TODO: remove this when we stop supporting NV_mesh_shader. */
+         bool nv;
       } mesh;
    };
 } shader_info;

src/compiler/spirv/spirv_to_nir.c

@@ -4458,9 +4458,18 @@ vtn_handle_preamble_instruction(struct vtn_builder *b, SpvOp opcode,
       break;
    }
 
+   case SpvOpExtension: {
+      /* Implementing both NV_mesh_shader and EXT_mesh_shader
+       * is difficult without knowing which we're dealing with.
+       * TODO: remove this when we stop supporting NV_mesh_shader.
+       */
+      const char *ext_name = (const char *)&w[1];
+      if (strcmp(ext_name, "SPV_NV_mesh_shader") == 0)
+         b->shader->info.mesh.nv = true;
+      break;
+   }
    case SpvOpSourceExtension:
    case SpvOpSourceContinued:
-   case SpvOpExtension:
    case SpvOpModuleProcessed:
       /* Unhandled, but these are for debug so that's ok. */
       break;