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Introduce parser-time optimization that replaces a function's local variables with registers.

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JerryScript-DCO-1.0-Signed-off-by: Ruben Ayrapetyan r.ayrapetyan@samsung.com
This commit is contained in:
Ruben Ayrapetyan
2015-08-21 14:19:04 +03:00
parent 91aecc3bd0
commit 5b9ce05491
11 changed files with 360 additions and 65 deletions
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jerry-core/parser/js/parser.cpp
+85 -6
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@@ -63,7 +63,7 @@ STATIC_STACK (scopes, scopes_tree)
static operand parse_expression (bool, jsp_eval_ret_store_t);
static void parse_statement (jsp_label_t *outermost_stmt_label_p);
static operand parse_assignment_expression (bool);
static void parse_source_element_list (bool);
static void parse_source_element_list (bool, bool);
static operand parse_argument_list (varg_list_type, operand, operand *);
static bool
@@ -404,7 +404,7 @@ parse_property_assignment (void)
jsp_label_t *masked_label_set_p = jsp_label_mask_set ();
parse_source_element_list (false);
parse_source_element_list (false, true);
jsp_label_restore_set (masked_label_set_p);
@@ -677,7 +677,7 @@ parse_function_declaration (void)
bool was_in_function = inside_function;
inside_function = true;
parse_source_element_list (false);
parse_source_element_list (false, true);
next_token_must_be (TOK_CLOSE_BRACE);
@@ -743,7 +743,7 @@ parse_function_expression (void)
jsp_label_t *masked_label_set_p = jsp_label_mask_set ();
parse_source_element_list (false);
parse_source_element_list (false, true);
jsp_label_restore_set (masked_label_set_p);
@@ -2965,7 +2965,10 @@ check_directive_prologue_for_use_strict ()
* ;
*/
static void
parse_source_element_list (bool is_global) /**< flag, indicating that we parsing global context */
parse_source_element_list (bool is_global, /**< flag, indicating that we parsing global context */
bool is_try_replace_local_vars_with_regs) /**< flag, indicating whether
* to try moving local function
* variables to registers */
{
const token_type end_tt = is_global ? TOK_EOF : TOK_CLOSE_BRACE;
@@ -3014,8 +3017,69 @@ parse_source_element_list (bool is_global) /**< flag, indicating that we parsing
{
scope_flags = (opcode_scope_code_flags_t) (scope_flags | OPCODE_SCOPE_CODE_FLAGS_NOT_REF_EVAL_IDENTIFIER);
}
rewrite_scope_code_flags (scope_code_flags_oc, scope_flags);
#ifdef CONFIG_PARSER_ENABLE_PARSE_TIME_BYTE_CODE_OPTIMIZER
if (is_try_replace_local_vars_with_regs
&& fe_scope_tree->type == SCOPE_TYPE_FUNCTION)
{
bool may_replace_vars_with_regs = (!inside_eval
&& !fe_scope_tree->ref_eval /* 'eval' can reference variables in a way,
* that can't be figured out through static
* analysis */
&& !fe_scope_tree->ref_arguments /* 'arguments' variable, if declared,
* should not be moved to a register,
* as it is currently declared in
* function's lexical environment
* (generally, the problem is the same,
* as with function's arguments) */
&& !fe_scope_tree->contains_with /* 'with' create new lexical environment
* and so can change way identifier
* is evaluated */
&& !fe_scope_tree->contains_try /* same for 'catch' */
&& !fe_scope_tree->contains_delete /* 'delete' handles variable's names,
* not values */
&& !fe_scope_tree->contains_functions); /* nested functions can reference
* variables of current function */
if (may_replace_vars_with_regs)
{
/* no subscopes, as no function declarations / eval etc. in the scope */
JERRY_ASSERT (fe_scope_tree->t.children_num == 0);
bool are_all_vars_replaced = true;
for (vm_instr_counter_t var_decl_pos = 0;
var_decl_pos < fe_scope_tree->var_decls_cout;
var_decl_pos++)
{
op_meta *om_p = (op_meta *) linked_list_element (fe_scope_tree->var_decls, var_decl_pos);
if (!dumper_try_replace_var_with_reg (fe_scope_tree, om_p))
{
are_all_vars_replaced = false;
}
}
if (are_all_vars_replaced)
{
/*
* All local variables were replaced with registers, so variable declarations could be removed.
*
* TODO:
* Support removal of a particular variable declaration, without removing the whole list.
*/
linked_list_free (fe_scope_tree->var_decls);
fe_scope_tree->var_decls = linked_list_init (sizeof (op_meta));
fe_scope_tree->var_decls_cout = 0;
}
}
}
#else /* CONFIG_PARSER_ENABLE_PARSE_TIME_BYTE_CODE_OPTIMIZER */
(void) is_try_replace_local_vars_with_regs;
#endif /* !CONFIG_PARSER_ENABLE_PARSE_TIME_BYTE_CODE_OPTIMIZER */
rewrite_reg_var_decl ();
dumper_finish_scope ();
} /* parse_source_element_list */
@@ -3087,7 +3151,22 @@ parser_parse_program (const jerry_api_char_t *source_p, /**< source code buffer
lexer_set_strict_mode (scopes_tree_strict_mode (STACK_TOP (scopes)));
skip_newlines ();
parse_source_element_list (true);
/*
* We don't try to perform replacement of local variables with registers for global code, eval code,
* and code of dynamically constructed functions.
*
* For global and eval code the replacement can be connected with side effects,
* that currently can only be figured out in runtime. For example, a variable
* can be redefined as accessor property of the Global object.
*
* For dynamically constructed functions replacement is not performed due to missing
* information about argument names (the names array is not passed to parser_parse_program).
* This could be solved by providing general way to iterate argument names during the optimization,
* or by expanding the optimization to run-time. In the second case, argument values could also
* be moved to registers.
*/
parse_source_element_list (true, false);
skip_newlines ();
JERRY_ASSERT (token_is (TOK_EOF));