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Introducing a function object's flag indicating whether Arguments object should be instantiated upon call of the function.

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The Arguments object is supposed to be unnecessary if function's code:
  - doesn't reference 'arguments' identifier;
  - doesn't reference 'eval' identifier (so, it doesn't perform direct call to eval).

JerryScript-DCO-1.0-Signed-off-by: Ruben Ayrapetyan r.ayrapetyan@samsung.com
This commit is contained in:
Ruben Ayrapetyan
2015-05-26 18:14:01 +03:00
parent b1a31c8144
commit ed4ff8e5bb
3 changed files with 81 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files
jerry-core/ecma/operations/ecma-function-object.cpp
+59 -14
View File
@@ -37,48 +37,60 @@
*/
/**
* Pack 'is_strict' flag and opcode index to value
* Pack 'is_strict', 'do_instantiate_arguments_object' flags and opcode index to value
* that can be stored in an [[Code]] internal property.
*
* @return packed value
*/
static uint32_t
ecma_pack_code_internal_property_value (bool is_strict, /**< is code strict? */
bool do_instantiate_args_obj, /**< should an Arguments object be
* instantiated for the code */
opcode_counter_t opcode_idx) /**< index of first opcode */
{
uint32_t value = opcode_idx;
const uint32_t is_strict_bit_offset = (uint32_t) (sizeof (value) * JERRY_BITSINBYTE - 1);
const uint32_t do_instantiate_arguments_object_bit_offset = (uint32_t) (sizeof (value) * JERRY_BITSINBYTE - 2);
JERRY_ASSERT (((value) & (1u << is_strict_bit_offset)) == 0);
JERRY_ASSERT (((value) & (1u << do_instantiate_arguments_object_bit_offset)) == 0);
if (is_strict)
{
value |= (1u << is_strict_bit_offset);
}
if (do_instantiate_args_obj)
{
value |= (1u << do_instantiate_arguments_object_bit_offset);
}
return value;
} /* ecma_pack_code_internal_property_value */
/**
* Unpack 'is_strict' flag and opcode index from value
* Unpack 'is_strict', 'do_instantiate_arguments_object' flags and opcode index from value
* that can be stored in an [[Code]] internal property.
*
* @return opcode index
*/
static opcode_counter_t
ecma_unpack_code_internal_property_value (uint32_t value, /**< packed value */
bool* out_is_strict_p) /**< out: is code strict? */
bool* out_is_strict_p, /**< out: is code strict? */
bool* out_do_instantiate_args_obj_p) /**< should an Arguments object be
* instantiated for the code */
{
JERRY_ASSERT (out_is_strict_p != NULL);
JERRY_ASSERT (out_do_instantiate_args_obj_p != NULL);
const uint32_t is_strict_bit_offset = (uint32_t) (sizeof (value) * JERRY_BITSINBYTE - 1);
const uint32_t do_instantiate_arguments_object_bit_offset = (uint32_t) (sizeof (value) * JERRY_BITSINBYTE - 2);
bool is_strict = ((value & (1u << is_strict_bit_offset)) != 0);
*out_is_strict_p = is_strict;
*out_is_strict_p = ((value & (1u << is_strict_bit_offset)) != 0);
*out_do_instantiate_args_obj_p = ((value & (1u << do_instantiate_arguments_object_bit_offset)) != 0);
value &= ~((1u << is_strict_bit_offset) | (1u << do_instantiate_arguments_object_bit_offset));
opcode_counter_t opcode_idx = (opcode_counter_t) (value & ~(1u << is_strict_bit_offset));
return opcode_idx;
return (opcode_counter_t) value;
} /* ecma_unpack_code_internal_property_value */
/**
@@ -144,6 +156,8 @@ ecma_op_create_function_object (ecma_string_t* formal_parameter_list_p[], /**< f
ecma_length_t formal_parameters_number, /**< formal parameters list's length */
ecma_object_t *scope_p, /**< function's scope */
bool is_strict, /**< 'strict' flag */
bool do_instantiate_arguments_object, /**< should an Arguments object be instantiated
* for the function object upon call */
opcode_counter_t first_opcode_idx) /**< index of first opcode of function's body */
{
// 1., 4., 13.
@@ -185,6 +199,7 @@ ecma_op_create_function_object (ecma_string_t* formal_parameter_list_p[], /**< f
// 12.
ecma_property_t *code_prop_p = ecma_create_internal_property (f, ECMA_INTERNAL_PROPERTY_CODE);
code_prop_p->u.internal_property.value = ecma_pack_code_internal_property_value (is_strict,
do_instantiate_arguments_object,
first_opcode_idx);
// 14.
@@ -339,10 +354,11 @@ ecma_op_create_external_function_object (ecma_external_pointer_t code_p) /**< po
} /* ecma_op_create_external_function_object */
/**
* Setup variables for arguments listed in formal parameter list.
* Setup variables for arguments listed in formal parameter list,
* and, if necessary, Arguments object with 'arguments' binding.
*
* See also:
* Declaration binding instantiation (ECMA-262 v5, 10.5), block 4
* Declaration binding instantiation (ECMA-262 v5, 10.5), block 4 and 7
*
* @return completion value
* Returned value must be freed with ecma_free_completion_value
@@ -352,7 +368,10 @@ ecma_function_call_setup_args_variables (ecma_object_t *func_obj_p, /**< Functio
ecma_object_t *env_p, /**< lexical environment */
const ecma_value_t *arguments_list_p, /**< arguments list */
ecma_length_t arguments_list_len, /**< length of argument list */
bool is_strict) /**< flag indicating strict mode */
bool is_strict, /**< flag indicating strict mode */
bool do_instantiate_arguments_object) /**< flag indicating whether
* Arguments object should be
* instantiated */
{
ecma_property_t *formal_parameters_prop_p = ecma_get_internal_property (func_obj_p,
ECMA_INTERNAL_PROPERTY_FORMAL_PARAMETERS);
@@ -417,6 +436,24 @@ ecma_function_call_setup_args_variables (ecma_object_t *func_obj_p, /**< Functio
}
}
if (do_instantiate_arguments_object)
{
/*
* According to ECMA-262 v5, 10.5, the Arguments object should be instantiated
* after instantiating declared functions, and only if there is no binding named 'arguments'
* by that time.
*
* However, we can setup Arguments object and 'arguments' binding here, because:
* - instantiation of Arguments object itself doesn't have any side effects;
* - if 'arguments' is name of a declared function in current scope,
* value of the binding would be overwritten, execution would proceed in correct state.
* - declaration of function, named 'arguments', is considered to be unrecommended (and so, rare) case,
* so instantiation of Arguments object here, in general, is supposed to not affect resource consumption
* significantly.
*/
JERRY_UNIMPLEMENTED ("Instantiate Arguments object and setup 'arguments' implicit variable");
}
return ecma_make_empty_completion_value ();
} /* ecma_function_call_setup_args_variables */
@@ -543,8 +580,11 @@ ecma_op_function_call (ecma_object_t *func_obj_p, /**< Function object */
uint32_t code_prop_value = code_prop_p->u.internal_property.value;
bool is_strict;
bool do_instantiate_args_obj;
// 8.
opcode_counter_t code_first_opcode_idx = ecma_unpack_code_internal_property_value (code_prop_value, &is_strict);
opcode_counter_t code_first_opcode_idx = ecma_unpack_code_internal_property_value (code_prop_value,
&is_strict,
&do_instantiate_args_obj);
ecma_value_t this_binding;
// 1.
@@ -576,7 +616,8 @@ ecma_op_function_call (ecma_object_t *func_obj_p, /**< Function object */
local_env_p,
arguments_list_p,
arguments_list_len,
is_strict),
is_strict,
do_instantiate_args_obj),
ret_value);
ecma_completion_value_t completion = vm_run_from_pos (code_first_opcode_idx,
@@ -769,14 +810,18 @@ ecma_op_function_declaration (ecma_object_t *lex_env_p, /**< lexical environment
ecma_string_t* formal_parameter_list_p[], /**< formal parameters list */
ecma_length_t formal_parameter_list_length, /**< length of formal parameters list */
bool is_strict, /**< flag indicating if function is declared in strict mode code */
bool do_instantiate_arguments_object, /**< flag, indicating whether an Arguments object
* should be instantiated for the function object
* upon call */
bool is_configurable_bindings) /**< flag indicating whether function
is declared in eval code */
* is declared in eval code */
{
// b.
ecma_object_t *func_obj_p = ecma_op_create_function_object (formal_parameter_list_p,
formal_parameter_list_length,
lex_env_p,
is_strict,
do_instantiate_arguments_object,
function_code_opcode_idx);
// c.
jerry-core/ecma/operations/ecma-function-object.h
+2
View File
@@ -34,6 +34,7 @@ ecma_op_create_function_object (ecma_string_t* formal_parameter_list_p[],
ecma_length_t formal_parameters_number,
ecma_object_t *scope_p,
bool is_strict,
bool do_instantiate_arguments_object,
opcode_counter_t first_opcode_idx);
extern ecma_object_t*
ecma_op_create_external_function_object (ecma_external_pointer_t code_p);
@@ -60,6 +61,7 @@ ecma_op_function_declaration (ecma_object_t *lex_env_p,
ecma_string_t* formal_parameter_list_p[],
ecma_length_t formal_parameter_list_length,
bool is_strict,
bool do_instantiate_arguments_object,
bool is_configurable_bindings);
/**
jerry-core/vm/opcodes.cpp
+20
View File
@@ -443,6 +443,7 @@ function_declaration (int_data_t *int_data, /**< interpreter context */
ecma_length_t args_number) /**< number of arguments */
{
bool is_strict = int_data->is_strict;
bool do_instantiate_arguments_object = true;
const bool is_configurable_bindings = int_data->is_eval_code;
const opcode_counter_t function_code_end_oc = (opcode_counter_t) (
@@ -455,6 +456,14 @@ function_declaration (int_data_t *int_data, /**< interpreter context */
{
is_strict = true;
}
if ((scope_flags & OPCODE_SCOPE_CODE_FLAGS_NOT_REF_ARGUMENTS_IDENTIFIER)
&& (scope_flags & OPCODE_SCOPE_CODE_FLAGS_NOT_REF_EVAL_IDENTIFIER))
{
/* the code doesn't use 'arguments' identifier
* and doesn't perform direct call to eval,
* so Arguments object can't be referenced */
do_instantiate_arguments_object = false;
}
ecma_string_t *function_name_string_p = ecma_new_ecma_string_from_lit_index (function_name_lit_id);
@@ -464,6 +473,7 @@ function_declaration (int_data_t *int_data, /**< interpreter context */
args_names,
args_number,
is_strict,
do_instantiate_arguments_object,
is_configurable_bindings);
ecma_deref_ecma_string (function_name_string_p);
@@ -541,6 +551,7 @@ opfunc_func_expr_n (opcode_t opdata, /**< operation data */
fill_params_list (int_data, params_number, params_names);
bool is_strict = int_data->is_strict;
bool do_instantiate_arguments_object = true;
function_code_end_oc = (opcode_counter_t) (read_meta_opcode_counter (OPCODE_META_TYPE_FUNCTION_END,
int_data) + int_data->pos);
@@ -552,6 +563,14 @@ opfunc_func_expr_n (opcode_t opdata, /**< operation data */
{
is_strict = true;
}
if ((scope_flags & OPCODE_SCOPE_CODE_FLAGS_NOT_REF_ARGUMENTS_IDENTIFIER)
&& (scope_flags & OPCODE_SCOPE_CODE_FLAGS_NOT_REF_EVAL_IDENTIFIER))
{
/* the code doesn't use 'arguments' identifier
* and doesn't perform direct call to eval,
* so Arguments object can't be referenced */
do_instantiate_arguments_object = false;
}
ecma_object_t *scope_p;
ecma_string_t *function_name_string_p = NULL;
@@ -576,6 +595,7 @@ opfunc_func_expr_n (opcode_t opdata, /**< operation data */
params_number,
scope_p,
is_strict,
do_instantiate_arguments_object,
int_data->pos);
ret_value = set_variable_value (int_data, lit_oc,