glsl: Add parser/compiler support for unsized array's length()

The unsized array length is computed with the following formula:

array.length() =
   max((buffer_object_size - offset_of_array) / stride_of_array, 0)

Of these, only the buffer size needs to be provided by the backends, the
frontend already knows the values of the two other variables.

This patch identifies the cases where we need to get the length of an
unsized array, injecting ir_unop_ssbo_unsized_array_length expressions
that will be lowered (in a later patch) to inject the formula mentioned
above.

It also adds the ir_unop_get_buffer_size expression that drivers will
implement to provide the buffer length.

v2:
- Do not define a triop that will force backends to implement the
  entire formula, they should only need to provide the buffer size
  since the other values are known by the frontend (Curro).

v3:
- Call state->has_shader_storage_buffer_objects() in ast_function.cpp instead
  of using state->ARB_shader_storage_buffer_object_enable (Tapani).

Signed-off-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>

diff --git a/src/glsl/ast_function.cpp b/src/glsl/ast_function.cpp
index 803edf5a14d68883dfa6de5f4688427f85067d90..ff5ecb954f01d121e90f4ec808484da5a4682e32 100644 (file)
--- 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 b9df9761920f07f542b695c2c54b09be9863a0c7..2c45b9edc0f88cf5976d1baeb7a8d8d72dee2ca8 100644 (file)
--- 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 48b6795cc0988ea7403c03412db8e66e2d22a981..43a2bf0ae1cd3d2850f18dacf15318812d4d8451 100644 (file)
--- a/src/glsl/ir.h
+++ b/src/glsl/ir.h
@@ -1424,10 +1424,27 @@ 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 3f0dea74e27b76f844a3da9c296e75d7d12b1f72..935571ae1d652b5d3f9256f922d44caef1db5579 100644 (file)
--- 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 238546ba22ec8053ad5da4be9b2c8827a5ba66bb..67a6e1bea170fb53c5d4673919e6e45cb81411ab 100644 (file)
--- 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 */

diff --git a/src/mesa/drivers/dri/i965/brw_fs_channel_expressions.cpp b/src/mesa/drivers/dri/i965/brw_fs_channel_expressions.cpp
index a8883a35ef296f38ff11c9e9ac2f332b81de9a5b..277b6cc3a60e5beaef0e7e94f4d96f182ae43e27 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_fs_channel_expressions.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_channel_expressions.cpp
@@ -379,6 +379,7 @@ ir_channel_expressions_visitor::visit_leave(ir_assignment *ir)
    }
 
    case ir_binop_ubo_load:
+   case ir_unop_get_buffer_size:
       unreachable("not yet supported");
 
    case ir_triop_fma:
@@ -430,6 +431,7 @@ ir_channel_expressions_visitor::visit_leave(ir_assignment *ir)
    case ir_triop_vector_insert:
    case ir_quadop_bitfield_insert:
    case ir_quadop_vector:
+   case ir_unop_ssbo_unsized_array_length:
       unreachable("should have been lowered");
 
    case ir_unop_unpack_half_2x16_split_x:

diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
index ac086a72eb1b275d23ffa39aa02250d63ecfbeed..3443e5cb7594052103aebb2c2c5eca3f9baeb1e7 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
@@ -1585,6 +1585,10 @@ vec4_visitor::visit(ir_expression *ir)
       emit(MOV(result_dst, op[0]));
       break;
 
+   case ir_unop_ssbo_unsized_array_length:
+      unreachable("not reached: should be handled by lower_ubo_reference");
+      break;
+
    case ir_binop_add:
       emit(ADD(result_dst, op[0], op[1]));
       break;
@@ -1791,6 +1795,10 @@ vec4_visitor::visit(ir_expression *ir)
       emit(RNDE(result_dst, op[0]));
       break;
 
+   case ir_unop_get_buffer_size:
+      unreachable("not reached: not implemented");
+      break;
+
    case ir_binop_min:
       emit_minmax(BRW_CONDITIONAL_L, result_dst, op[0], op[1]);
       break;

diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp
index afb400f714cbe8b20916b0cab2543be30dd21071..4201a80cf620440e6683f0bb7d518fb2cb3a70b0 100644 (file)
--- a/src/mesa/program/ir_to_mesa.cpp
+++ b/src/mesa/program/ir_to_mesa.cpp
@@ -1344,9 +1344,11 @@ ir_to_mesa_visitor::visit(ir_expression *ir)
    case ir_unop_dFdy_coarse:
    case ir_unop_dFdy_fine:
    case ir_unop_subroutine_to_int:
+   case ir_unop_get_buffer_size:
       assert(!"not supported");
       break;
 
+   case ir_unop_ssbo_unsized_array_length:
    case ir_quadop_vector:
       /* This operation should have already been handled.
        */

diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index 5896f6518b50b54df3ab89270a1dc15b36499b07..633e90ffa3874cf1fa7eb72214bcd8bf03b31613 100644 (file)
--- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -2217,10 +2217,15 @@ glsl_to_tgsi_visitor::visit(ir_expression *ir)
    case ir_triop_vector_insert:
    case ir_binop_carry:
    case ir_binop_borrow:
+   case ir_unop_ssbo_unsized_array_length:
       /* This operation is not supported, or should have already been handled.
        */
       assert(!"Invalid ir opcode in glsl_to_tgsi_visitor::visit()");
       break;
+
+   case ir_unop_get_buffer_size:
+      assert(!"Not implemented yet");
+      break;
    }
 
    this->result = result_src;