From edc108765e71795755efcf7be479e3bcdd7b7ecf Mon Sep 17 00:00:00 2001
From: Timothy Arceri <timothy.arceri@collabora.com>
Date: Sat, 6 Feb 2016 09:30:00 +1100
Subject: [PATCH] mesa: compute sampler index in ir_to_mesa rather than using
 UniformHash

The aim of this is to work towards removing UniformHash from the program
struct so that we don't need to hold onto it in memory and pass it around
outside the linker.

Reviewed-by: Dave Airlie <airlied@redhat.com>
---
 src/mesa/program/ir_to_mesa.cpp | 81 +++++++++++++++++++++++++++++++--
 1 file changed, 78 insertions(+), 3 deletions(-)

diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp
index 68cc4a5e0cd..f2902c9f863 100644
--- a/src/mesa/program/ir_to_mesa.cpp
+++ b/src/mesa/program/ir_to_mesa.cpp
@@ -1539,6 +1539,82 @@ get_assignment_lhs(ir_dereference *ir, ir_to_mesa_visitor *v)
    return dst_reg(v->result);
 }
 
+/* Calculate the sampler index and also calculate the base uniform location
+ * for struct members.
+ */
+static void
+calc_sampler_offsets(struct gl_shader_program *prog, ir_dereference *deref,
+                     unsigned *offset, unsigned *array_elements,
+                     unsigned *location)
+{
+   if (deref->ir_type == ir_type_dereference_variable)
+      return;
+
+   switch (deref->ir_type) {
+   case ir_type_dereference_array: {
+      ir_dereference_array *deref_arr = deref->as_dereference_array();
+      ir_constant *array_index =
+         deref_arr->array_index->constant_expression_value();
+
+      if (!array_index) {
+	 /* GLSL 1.10 and 1.20 allowed variable sampler array indices,
+	  * while GLSL 1.30 requires that the array indices be
+	  * constant integer expressions.  We don't expect any driver
+	  * to actually work with a really variable array index, so
+	  * all that would work would be an unrolled loop counter that ends
+	  * up being constant above.
+	  */
+	 ralloc_strcat(&prog->InfoLog,
+		       "warning: Variable sampler array index unsupported.\n"
+		       "This feature of the language was removed in GLSL 1.20 "
+		       "and is unlikely to be supported for 1.10 in Mesa.\n");
+      } else {
+         *offset += array_index->value.u[0] * *array_elements;
+      }
+
+      *array_elements *= deref_arr->array->type->length;
+
+      calc_sampler_offsets(prog, deref_arr->array->as_dereference(),
+                           offset, array_elements, location);
+      break;
+   }
+
+   case ir_type_dereference_record: {
+      ir_dereference_record *deref_record = deref->as_dereference_record();
+      unsigned field_index =
+         deref_record->record->type->field_index(deref_record->field);
+      *location +=
+         deref_record->record->type->record_location_offset(field_index);
+      calc_sampler_offsets(prog, deref_record->record->as_dereference(),
+                           offset, array_elements, location);
+      break;
+   }
+
+   default:
+      unreachable("Invalid deref type");
+      break;
+   }
+}
+
+static int
+get_sampler_uniform_value(class ir_dereference *sampler,
+                          struct gl_shader_program *shader_program,
+                          const struct gl_program *prog)
+{
+   GLuint shader = _mesa_program_enum_to_shader_stage(prog->Target);
+   ir_variable *var = sampler->variable_referenced();
+   unsigned location = var->data.location;
+   unsigned array_elements = 1;
+   unsigned offset = 0;
+
+   calc_sampler_offsets(shader_program, sampler, &offset, &array_elements,
+                        &location);
+
+   assert(shader_program->UniformStorage[location].opaque[shader].active);
+   return shader_program->UniformStorage[location].opaque[shader].index +
+          offset;
+}
+
 /**
  * Process the condition of a conditional assignment
  *
@@ -1988,9 +2064,8 @@ ir_to_mesa_visitor::visit(ir_texture *ir)
    if (ir->shadow_comparitor)
       inst->tex_shadow = GL_TRUE;
 
-   inst->sampler = _mesa_get_sampler_uniform_value(ir->sampler,
-						   this->shader_program,
-						   this->prog);
+   inst->sampler = get_sampler_uniform_value(ir->sampler, shader_program,
+                                             prog);
 
    switch (sampler_type->sampler_dimensionality) {
    case GLSL_SAMPLER_DIM_1D:
-- 
2.30.2