5 files changed, 53 insertions, 7 deletions

diff --git a/src/glsl/ast_function.cpp b/src/glsl/ast_function.cpp
index 803edf5a14d..ff5ecb954f0 100644
--- a/src/glsl/ast_function.cpp
+++ b/src/glsl/ast_function.cpp
@@ -1593,11 +1593,16 @@ ast_function_expression::handle_method(exec_list *instructions,
 
       if (op->type->is_array()) {
          if (op->type->is_unsized_array()) {
-            _mesa_glsl_error(&loc, state, "length called on unsized array");
-            goto fail;
+            if (!state->has_shader_storage_buffer_objects()) {
+               _mesa_glsl_error(&loc, state, "length called on unsized array"
+                                             " only available with "
+                                             "ARB_shader_storage_buffer_object");
+            }
+            /* Calculate length of an unsized array in run-time */
+            result = new(ctx) ir_expression(ir_unop_ssbo_unsized_array_length, op);
+         } else {
+            result = new(ctx) ir_constant(op->type->array_size());
          }
-
-         result = new(ctx) ir_constant(op->type->array_size());
       } else if (op->type->is_vector()) {
          if (state->ARB_shading_language_420pack_enable) {
             /* .length() returns int. */
diff --git a/src/glsl/ir.cpp b/src/glsl/ir.cpp
index b9df9761920..2c45b9edc0f 100644
--- a/src/glsl/ir.cpp
+++ b/src/glsl/ir.cpp
@@ -342,6 +342,11 @@ ir_expression::ir_expression(int op, ir_rvalue *op0)
 					   op0->type->vector_elements, 1);
       break;
 
+   case ir_unop_get_buffer_size:
+   case ir_unop_ssbo_unsized_array_length:
+      this->type = glsl_type::int_type;
+      break;
+
    default:
       assert(!"not reached: missing automatic type setup for ir_expression");
       this->type = op0->type;
@@ -571,6 +576,8 @@ static const char *const operator_strs[] = {
    "noise",
    "subroutine_to_int",
    "interpolate_at_centroid",
+   "get_buffer_size",
+   "ssbo_unsized_array_length",
    "+",
    "-",
    "*",
diff --git a/src/glsl/ir.h b/src/glsl/ir.h
index 48b6795cc09..43a2bf0ae1c 100644
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -1425,9 +1425,26 @@ enum ir_expression_operation {
    ir_unop_interpolate_at_centroid,
 
    /**
+    * Ask the driver for the total size of a buffer block.
+    *
+    * operand0 is the ir_constant buffer block index in the linked shader.
+    */
+   ir_unop_get_buffer_size,
+
+   /**
+    * Calculate length of an unsized array inside a buffer block.
+    * This opcode is going to be replaced in a lowering pass inside
+    * the linker.
+    *
+    * operand0 is the unsized array's ir_value for the calculation
+    * of its length.
+    */
+   ir_unop_ssbo_unsized_array_length,
+
+   /**
     * A sentinel marking the last of the unary operations.
     */
-   ir_last_unop = ir_unop_interpolate_at_centroid,
+   ir_last_unop = ir_unop_ssbo_unsized_array_length,
 
    ir_binop_add,
    ir_binop_sub,
diff --git a/src/glsl/ir_validate.cpp b/src/glsl/ir_validate.cpp
index 3f0dea74e27..935571ae1d6 100644
--- a/src/glsl/ir_validate.cpp
+++ b/src/glsl/ir_validate.cpp
@@ -409,6 +409,17 @@ ir_validate::visit_leave(ir_expression *ir)
       assert(ir->operands[0]->type->is_float());
       break;
 
+   case ir_unop_get_buffer_size:
+      assert(ir->type == glsl_type::int_type);
+      assert(ir->operands[0]->type == glsl_type::uint_type);
+      break;
+
+   case ir_unop_ssbo_unsized_array_length:
+      assert(ir->type == glsl_type::int_type);
+      assert(ir->operands[0]->type->is_array());
+      assert(ir->operands[0]->type->is_unsized_array());
+      break;
+
    case ir_unop_d2f:
       assert(ir->operands[0]->type->base_type == GLSL_TYPE_DOUBLE);
       assert(ir->type->base_type == GLSL_TYPE_FLOAT);
diff --git a/src/glsl/link_uniforms.cpp b/src/glsl/link_uniforms.cpp
index 238546ba22e..67a6e1bea17 100644
--- a/src/glsl/link_uniforms.cpp
+++ b/src/glsl/link_uniforms.cpp
@@ -231,9 +231,15 @@ program_resource_visitor::recursion(const glsl_type *t, char **name,
       if (record_type == NULL && t->fields.array->is_record())
          record_type = t->fields.array;
 
-      record_array_count *= t->length;
+      unsigned length = t->length;
+      /* Shader storage block unsized arrays: add subscript [0] to variable
+       * names */
+      if (t->is_unsized_array())
+         length = 1;
 
-      for (unsigned i = 0; i < t->length; i++) {
+      record_array_count *= length;
+
+      for (unsigned i = 0; i < length; i++) {
 	 size_t new_length = name_length;
 
 	 /* Append the subscript to the current variable name */