glsl: Allow geometry shader input instance arrays to be unsized.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>

src/glsl/ast.h

@@ -908,11 +908,13 @@ class ast_interface_block : public ast_node {
 public:
    ast_interface_block(ast_type_qualifier layout,
                        const char *instance_name,
+                       bool is_array,
                        ast_expression *array_size)
    : layout(layout), block_name(NULL), instance_name(instance_name),
-     array_size(array_size)
+     is_array(is_array), array_size(array_size)
    {
-      /* empty */
+      if (!is_array)
+         assert(array_size == NULL);
    }
 
    virtual ir_rvalue *hir(exec_list *instructions,
@@ -933,13 +935,19 @@ public:
    exec_list declarations;
 
    /**
-    * Declared array size of the block instance
-    *
-    * If the block is not declared as an array, this field will be \c NULL.
+    * True if the block is declared as an array
     *
     * \note
     * A block can only be an array if it also has an instance name.  If this
-    * field is not \c NULL, ::instance_name must also not be \c NULL.
+    * field is true, ::instance_name must also not be \c NULL.
+    */
+   bool is_array;
+
+   /**
+    * Declared array size of the block instance
+    *
+    * If the block is not declared as an array or if the block instance array
+    * is unsized, this field will be \c NULL.
     */
    ast_expression *array_size;
 };

src/glsl/ast_to_hir.cpp

@@ -4409,7 +4409,34 @@ ast_interface_block::hir(exec_list *instructions,
    if (this->instance_name) {
       ir_variable *var;
 
-      if (this->array_size != NULL) {
+      if (this->is_array) {
+         /* Section 4.3.7 (Interface Blocks) of the GLSL 1.50 spec says:
+          *
+          *     For uniform blocks declared an array, each individual array
+          *     element corresponds to a separate buffer object backing one
+          *     instance of the block. As the array size indicates the number
+          *     of buffer objects needed, uniform block array declarations
+          *     must specify an array size.
+          *
+          * And a few paragraphs later:
+          *
+          *     Geometry shader input blocks must be declared as arrays and
+          *     follow the array declaration and linking rules for all
+          *     geometry shader inputs. All other input and output block
+          *     arrays must specify an array size.
+          *
+          * The upshot of this is that the only circumstance where an
+          * interface array size *doesn't* need to be specified is on a
+          * geometry shader input.
+          */
+         if (this->array_size == NULL &&
+             (state->target != geometry_shader || !this->layout.flags.q.in)) {
+            _mesa_glsl_error(&loc, state,
+                             "only geometry shader inputs may be unsized "
+                             "instance block arrays");
+
+         }
+
          const glsl_type *block_array_type =
             process_array_type(&loc, block_type, this->array_size, state);
 
@@ -4429,7 +4456,7 @@ ast_interface_block::hir(exec_list *instructions,
       /* In order to have an array size, the block must also be declared with
        * an instane name.
        */
-      assert(this->array_size == NULL);
+      assert(!this->is_array);
 
       for (unsigned i = 0; i < num_variables; i++) {
          ir_variable *var =

src/glsl/glsl_parser.yy

@@ -2243,25 +2243,22 @@ instance_name_opt:
    /* empty */
    {
       $$ = new(state) ast_interface_block(*state->default_uniform_qualifier,
-                                          NULL, NULL);
+                                          NULL, false, NULL);
    }
    | NEW_IDENTIFIER
    {
       $$ = new(state) ast_interface_block(*state->default_uniform_qualifier,
-                                          $1, NULL);
+                                          $1, false, NULL);
    }
    | NEW_IDENTIFIER '[' constant_expression ']'
    {
       $$ = new(state) ast_interface_block(*state->default_uniform_qualifier,
-                                          $1, $3);
+                                          $1, true, $3);
    }
    | NEW_IDENTIFIER '[' ']'
    {
-      _mesa_glsl_error(& @1, state,
-                       "instance block arrays must be explicitly sized");
-
       $$ = new(state) ast_interface_block(*state->default_uniform_qualifier,
-                                          $1, NULL);
+                                          $1, true, NULL);
    }
    ;