glsl: add resize_tes_inputs() to the nir linker

We will switch from the GLSL IR version to this in a following patch.

Acked-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/28538>

src/compiler/glsl/gl_nir_link_varyings.c

@@ -565,6 +565,94 @@ check_location_aliasing(struct explicit_location_info explicit_locations[][4],
    return true;
 }
 
+static void
+resize_input_array(nir_shader *shader, struct gl_shader_program *prog,
+                   unsigned stage, unsigned num_vertices)
+{
+   nir_foreach_shader_in_variable(var, shader) {
+      if (!glsl_type_is_array(var->type) || var->data.patch)
+         continue;
+
+      unsigned size = glsl_array_size(var->type);
+
+      if (stage == MESA_SHADER_GEOMETRY) {
+         /* Generate a link error if the shader has declared this array with
+          * an incorrect size.
+          */
+         if (!var->data.implicit_sized_array &&
+             size != -1 && size != num_vertices) {
+            linker_error(prog, "size of array %s declared as %u, "
+                         "but number of input vertices is %u\n",
+                         var->name, size, num_vertices);
+            break;
+         }
+
+         /* Generate a link error if the shader attempts to access an input
+          * array using an index too large for its actual size assigned at
+          * link time.
+          */
+         if (var->data.max_array_access >= (int)num_vertices) {
+            linker_error(prog, "%s shader accesses element %i of "
+                         "%s, but only %i input vertices\n",
+                         _mesa_shader_stage_to_string(stage),
+                         var->data.max_array_access, var->name, num_vertices);
+            break;
+         }
+      }
+
+      var->type = glsl_array_type(var->type->fields.array, num_vertices, 0);
+      var->data.max_array_access = num_vertices - 1;
+   }
+
+   nir_fixup_deref_types(shader);
+}
+
+/**
+ * Resize tessellation evaluation per-vertex inputs to the size of
+ * tessellation control per-vertex outputs.
+ */
+void
+resize_tes_inputs(const struct gl_constants *consts,
+                  struct gl_shader_program *prog)
+{
+   if (prog->_LinkedShaders[MESA_SHADER_TESS_EVAL] == NULL)
+      return;
+
+   struct gl_linked_shader *tcs = prog->_LinkedShaders[MESA_SHADER_TESS_CTRL];
+   struct gl_linked_shader *tes = prog->_LinkedShaders[MESA_SHADER_TESS_EVAL];
+
+   /* If no control shader is present, then the TES inputs are statically
+    * sized to MaxPatchVertices; the actual size of the arrays won't be
+    * known until draw time.
+    */
+   const int num_vertices = tcs
+      ? tcs->Program->info.tess.tcs_vertices_out
+      : consts->MaxPatchVertices;
+
+   resize_input_array(tes->Program->nir, prog, MESA_SHADER_TESS_EVAL,
+                      num_vertices);
+   if (tcs) {
+      /* Convert the gl_PatchVerticesIn system value into a constant, since
+       * the value is known at this point.
+       */
+      nir_variable *var =
+         nir_find_variable_with_location(tes->Program->nir,
+                                         nir_var_system_value,
+                                         SYSTEM_VALUE_VERTICES_IN);
+      if (var) {
+         var->data.location = 0;
+         var->data.explicit_location = false;
+         var->data.mode = nir_var_mem_constant;
+
+         nir_constant *val = rzalloc(var, nir_constant);
+         val->values[0].i32 = num_vertices;
+         var->constant_initializer = val;
+
+         nir_fixup_deref_modes(tes->Program->nir);
+      }
+   }
+}
+
 static bool
 validate_explicit_variable_location(const struct gl_constants *consts,
                                     struct explicit_location_info explicit_locations[][4],

src/compiler/glsl/gl_nir_link_varyings.h

@@ -216,6 +216,10 @@ xfb_decl_is_varying(const struct xfb_decl *xfb_decl)
    return !xfb_decl->next_buffer_separator && !xfb_decl->skip_components;
 }
 
+void
+resize_tes_inputs(const struct gl_constants *consts,
+                  struct gl_shader_program *prog);
+
 bool
 gl_assign_attribute_or_color_locations(const struct gl_constants *consts,
                                        struct gl_shader_program *prog);