glsl ubo/ssbo: Move common code into lower_buffer_access::setup_buffer_access

This code will also be usable by the pass to lower shared variables.

Note, that *const_offset is adjusted by setup_buffer_access so it must
be initialized before calling setup_buffer_access.

v2:
 * Add comment for lower_buffer_access::setup_buffer_access

Signed-off-by: Jordan Justen <[email protected]>
Reviewed-by: Iago Toral Quiroga <[email protected]>
Reviewed-by: Kristian Høgsberg <[email protected]>

1 files changed, 177 insertions, 0 deletions

diff --git a/src/glsl/lower_buffer_access.cpp b/src/glsl/lower_buffer_access.cpp
index 0f5ba17bbf9..7e9d516d74a 100644
--- a/src/glsl/lower_buffer_access.cpp
+++ b/src/glsl/lower_buffer_access.cpp
@@ -303,4 +303,181 @@ lower_buffer_access::is_dereferenced_thing_row_major(const ir_rvalue *deref)
    return false;
 }
 
+/**
+ * This function initializes various values that will be used later by
+ * emit_access when actually emitting loads or stores.
+ *
+ * Note: const_offset is an input as well as an output, clients must
+ * initialize it to the offset of the variable in the underlying block, and
+ * this function will adjust it by adding the constant offset of the member
+ * being accessed into that variable.
+ */
+void
+lower_buffer_access::setup_buffer_access(void *mem_ctx,
+                                         ir_variable *var,
+                                         ir_rvalue *deref,
+                                         ir_rvalue **offset,
+                                         unsigned *const_offset,
+                                         bool *row_major,
+                                         int *matrix_columns,
+                                         unsigned packing)
+{
+   *offset = new(mem_ctx) ir_constant(0u);
+   *row_major = is_dereferenced_thing_row_major(deref);
+   *matrix_columns = 1;
+
+   /* Calculate the offset to the start of the region of the UBO
+    * dereferenced by *rvalue.  This may be a variable offset if an
+    * array dereference has a variable index.
+    */
+   while (deref) {
+      switch (deref->ir_type) {
+      case ir_type_dereference_variable: {
+         deref = NULL;
+         break;
+      }
+
+      case ir_type_dereference_array: {
+         ir_dereference_array *deref_array = (ir_dereference_array *) deref;
+         unsigned array_stride;
+         if (deref_array->array->type->is_vector()) {
+            /* We get this when storing or loading a component out of a vector
+             * with a non-constant index. This happens for v[i] = f where v is
+             * a vector (or m[i][j] = f where m is a matrix). If we don't
+             * lower that here, it gets turned into v = vector_insert(v, i,
+             * f), which loads the entire vector, modifies one component and
+             * then write the entire thing back.  That breaks if another
+             * thread or SIMD channel is modifying the same vector.
+             */
+            array_stride = 4;
+            if (deref_array->array->type->is_double())
+               array_stride *= 2;
+         } else if (deref_array->array->type->is_matrix() && *row_major) {
+            /* When loading a vector out of a row major matrix, the
+             * step between the columns (vectors) is the size of a
+             * float, while the step between the rows (elements of a
+             * vector) is handled below in emit_ubo_loads.
+             */
+            array_stride = 4;
+            if (deref_array->array->type->is_double())
+               array_stride *= 2;
+            *matrix_columns = deref_array->array->type->matrix_columns;
+         } else if (deref_array->type->without_array()->is_interface()) {
+            /* We're processing an array dereference of an interface instance
+             * array. The thing being dereferenced *must* be a variable
+             * dereference because interfaces cannot be embedded in other
+             * types. In terms of calculating the offsets for the lowering
+             * pass, we don't care about the array index. All elements of an
+             * interface instance array will have the same offsets relative to
+             * the base of the block that backs them.
+             */
+            deref = deref_array->array->as_dereference();
+            break;
+         } else {
+            /* Whether or not the field is row-major (because it might be a
+             * bvec2 or something) does not affect the array itself. We need
+             * to know whether an array element in its entirety is row-major.
+             */
+            const bool array_row_major =
+               is_dereferenced_thing_row_major(deref_array);
+
+            /* The array type will give the correct interface packing
+             * information
+             */
+            if (packing == GLSL_INTERFACE_PACKING_STD430) {
+               array_stride = deref_array->type->std430_array_stride(array_row_major);
+            } else {
+               array_stride = deref_array->type->std140_size(array_row_major);
+               array_stride = glsl_align(array_stride, 16);
+            }
+         }
+
+         ir_rvalue *array_index = deref_array->array_index;
+         if (array_index->type->base_type == GLSL_TYPE_INT)
+            array_index = i2u(array_index);
+
+         ir_constant *const_index =
+            array_index->constant_expression_value(NULL);
+         if (const_index) {
+            *const_offset += array_stride * const_index->value.u[0];
+         } else {
+            *offset = add(*offset,
+                          mul(array_index,
+                              new(mem_ctx) ir_constant(array_stride)));
+         }
+         deref = deref_array->array->as_dereference();
+         break;
+      }
+
+      case ir_type_dereference_record: {
+         ir_dereference_record *deref_record = (ir_dereference_record *) deref;
+         const glsl_type *struct_type = deref_record->record->type;
+         unsigned intra_struct_offset = 0;
+
+         for (unsigned int i = 0; i < struct_type->length; i++) {
+            const glsl_type *type = struct_type->fields.structure[i].type;
+
+            ir_dereference_record *field_deref = new(mem_ctx)
+               ir_dereference_record(deref_record->record,
+                                     struct_type->fields.structure[i].name);
+            const bool field_row_major =
+               is_dereferenced_thing_row_major(field_deref);
+
+            ralloc_free(field_deref);
+
+            unsigned field_align = 0;
+
+            if (packing == GLSL_INTERFACE_PACKING_STD430)
+               field_align = type->std430_base_alignment(field_row_major);
+            else
+               field_align = type->std140_base_alignment(field_row_major);
+
+            intra_struct_offset = glsl_align(intra_struct_offset, field_align);
+
+            if (strcmp(struct_type->fields.structure[i].name,
+                       deref_record->field) == 0)
+               break;
+
+            if (packing == GLSL_INTERFACE_PACKING_STD430)
+               intra_struct_offset += type->std430_size(field_row_major);
+            else
+               intra_struct_offset += type->std140_size(field_row_major);
+
+            /* If the field just examined was itself a structure, apply rule
+             * #9:
+             *
+             *     "The structure may have padding at the end; the base offset
+             *     of the member following the sub-structure is rounded up to
+             *     the next multiple of the base alignment of the structure."
+             */
+            if (type->without_array()->is_record()) {
+               intra_struct_offset = glsl_align(intra_struct_offset,
+                                                field_align);
+
+            }
+         }
+
+         *const_offset += intra_struct_offset;
+         deref = deref_record->record->as_dereference();
+         break;
+      }
+
+      case ir_type_swizzle: {
+         ir_swizzle *deref_swizzle = (ir_swizzle *) deref;
+
+         assert(deref_swizzle->mask.num_components == 1);
+
+         *const_offset += deref_swizzle->mask.x * sizeof(int);
+         deref = deref_swizzle->val->as_dereference();
+         break;
+      }
+
+      default:
+         assert(!"not reached");
+         deref = NULL;
+         break;
+      }
+   }
+}
+
 } /* namespace lower_buffer_access */