ACPI_MODULE_NAME ("dsutils")
+/*******************************************************************************
+ *
+ * FUNCTION: acpi_ds_clear_implicit_return
+ *
+ * PARAMETERS: walk_state - Current State
+ *
+ * RETURN: None.
+ *
+ * DESCRIPTION: Clear and remove a reference on an implicit return value. Used
+ * to delete "stale" return values (if enabled, the return value
+ * from every operator is saved at least momentarily, in case the
+ * parent method exits.)
+ *
+ ******************************************************************************/
+
+void
+acpi_ds_clear_implicit_return (
+ struct acpi_walk_state *walk_state)
+{
+ ACPI_FUNCTION_NAME ("ds_clear_implicit_return");
+
+
+ /*
+ * Slack must be enabled for this feature
+ */
+ if (!acpi_gbl_enable_interpreter_slack) {
+ return;
+ }
+
+ if (walk_state->implicit_return_obj) {
+ /*
+ * Delete any "stale" implicit return. However, in
+ * complex statements, the implicit return value can be
+ * bubbled up several levels.
+ */
+ ACPI_DEBUG_PRINT ((ACPI_DB_DISPATCH,
+ "Removing reference on stale implicit return obj %p\n",
+ walk_state->implicit_return_obj));
+
+ acpi_ut_remove_reference (walk_state->implicit_return_obj);
+ walk_state->implicit_return_obj = NULL;
+ }
+}
+
+
#ifndef ACPI_NO_METHOD_EXECUTION
+/*******************************************************************************
+ *
+ * FUNCTION: acpi_ds_do_implicit_return
+ *
+ * PARAMETERS: return_desc - The return value
+ * walk_state - Current State
+ * add_reference - True if a reference should be added to the
+ * return object
+ *
+ * RETURN: TRUE if implicit return enabled, FALSE otherwise
+ *
+ * DESCRIPTION: Implements the optional "implicit return". We save the result
+ * of every ASL operator and control method invocation in case the
+ * parent method exit. Before storing a new return value, we
+ * delete the previous return value.
+ *
+ ******************************************************************************/
+
+u8
+acpi_ds_do_implicit_return (
+ union acpi_operand_object *return_desc,
+ struct acpi_walk_state *walk_state,
+ u8 add_reference)
+{
+ ACPI_FUNCTION_NAME ("ds_do_implicit_return");
+
+
+ /*
+ * Slack must be enabled for this feature, and we must
+ * have a valid return object
+ */
+ if ((!acpi_gbl_enable_interpreter_slack) ||
+ (!return_desc)) {
+ return (FALSE);
+ }
+
+ ACPI_DEBUG_PRINT ((ACPI_DB_DISPATCH,
+ "Result %p will be implicitly returned; Prev=%p\n",
+ return_desc,
+ walk_state->implicit_return_obj));
+
+ /*
+ * Delete any "stale" implicit return value first. However, in
+ * complex statements, the implicit return value can be
+ * bubbled up several levels, so we don't clear the value if it
+ * is the same as the return_desc.
+ */
+ if (walk_state->implicit_return_obj) {
+ if (walk_state->implicit_return_obj == return_desc) {
+ return (TRUE);
+ }
+ acpi_ds_clear_implicit_return (walk_state);
+ }
+
+ /* Save the implicit return value, add a reference if requested */
+
+ walk_state->implicit_return_obj = return_desc;
+ if (add_reference) {
+ acpi_ut_add_reference (return_desc);
+ }
+
+ return (TRUE);
+}
+
+
/*******************************************************************************
*
* FUNCTION: acpi_ds_is_result_used
{
const struct acpi_opcode_info *parent_info;
-
ACPI_FUNCTION_TRACE_PTR ("ds_is_result_used", op);
}
/*
+ * We know that this operator is not a
+ * Return() operator (would not come here.) The following code is the
+ * optional support for a so-called "implicit return". Some AML code
+ * assumes that the last value of the method is "implicitly" returned
+ * to the caller. Just save the last result as the return value.
+ * NOTE: this is optional because the ASL language does not actually
+ * support this behavior.
+ */
+ acpi_ds_do_implicit_return (walk_state->result_obj, walk_state, TRUE);
+
+ /*
+ * Now determine if the parent will use the result
+ *
* If there is no parent, or the parent is a scope_op, we are executing
* at the method level. An executing method typically has no parent,
* since each method is parsed separately. A method invoked externally
*/
if ((!op->common.parent) ||
(op->common.parent->common.aml_opcode == AML_SCOPE_OP)) {
- /*
- * If this is the last statement in the method, we know it is not a
- * Return() operator (would not come here.) The following code is the
- * optional support for a so-called "implicit return". Some AML code
- * assumes that the last value of the method is "implicitly" returned
- * to the caller. Just save the last result as the return value.
- * NOTE: this is optional because the ASL language does not actually
- * support this behavior.
- */
- if ((acpi_gbl_enable_interpreter_slack) &&
- (walk_state->parser_state.aml >= walk_state->parser_state.aml_end)) {
- ACPI_DEBUG_PRINT ((ACPI_DB_DISPATCH,
- "Result of [%s] will be implicitly returned\n",
- acpi_ps_get_opcode_name (op->common.aml_opcode)));
-
- /* Use the top of the result stack as the implicit return value */
-
- walk_state->return_desc = walk_state->results->results.obj_desc[0];
- return_VALUE (TRUE);
- }
-
/* No parent, the return value cannot possibly be used */
+ ACPI_DEBUG_PRINT ((ACPI_DB_DISPATCH, "At Method level, result of [%s] not used\n",
+ acpi_ps_get_opcode_name (op->common.aml_opcode)));
return_VALUE (FALSE);
}
}
if (!acpi_ds_is_result_used (op, walk_state)) {
- /*
- * Must pop the result stack (obj_desc should be equal to result_obj)
- */
+ /* Must pop the result stack (obj_desc should be equal to result_obj) */
+
status = acpi_ds_result_pop (&obj_desc, walk_state);
if (ACPI_SUCCESS (status)) {
acpi_ut_remove_reference (result_obj);
ACPI_FUNCTION_TRACE_PTR ("ds_clear_operands", walk_state);
- /*
- * Remove a reference on each operand on the stack
- */
+ /* Remove a reference on each operand on the stack */
+
for (i = 0; i < walk_state->num_operands; i++) {
/*
* Remove a reference to all operands, including both
return_ACPI_STATUS (status);
}
- /*
- * All prefixes have been handled, and the name is
- * in name_string
- */
-
+ /* All prefixes have been handled, and the name is in name_string */
/*
* Special handling for buffer_field declarations. This is a deferred
*
* FUNCTION: acpi_ds_create_operands
*
- * PARAMETERS: first_arg - First argument of a parser argument tree
+ * PARAMETERS: walk_state - Current state
+ * first_arg - First argument of a parser argument tree
*
* RETURN: Status
*
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