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php-src/Zend/Optimizer/escape_analysis.c
Niels Dossche f21947a7ae
Merge branch 'PHP-8.2' into PHP-8.3 
* PHP-8.2:
  Fix GH-15028: Memory leak in ext/phar/stream.c
  Fix GH-15023: Memory leak in Zend/zend_ini.c
  Fix GH-15020: Memory leak in Zend/Optimizer/escape_analysis.c
2024-07-19 14:59:44 +02:00

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/*
+----------------------------------------------------------------------+
| Zend OPcache, Escape Analysis |
+----------------------------------------------------------------------+
| Copyright (c) The PHP Group |
+----------------------------------------------------------------------+
| This source file is subject to version 3.01 of the PHP license, |
| that is bundled with this package in the file LICENSE, and is |
| available through the world-wide-web at the following url: |
| https://www.php.net/license/3_01.txt |
| If you did not receive a copy of the PHP license and are unable to |
| obtain it through the world-wide-web, please send a note to |
| license@php.net so we can mail you a copy immediately. |
+----------------------------------------------------------------------+
| Authors: Dmitry Stogov <dmitry@php.net> |
+----------------------------------------------------------------------+
*/
#include "Optimizer/zend_optimizer.h"
#include "Optimizer/zend_optimizer_internal.h"
#include "zend_bitset.h"
#include "zend_cfg.h"
#include "zend_ssa.h"
#include "zend_inference.h"
#include "zend_dump.h"
/*
* T. Kotzmann and H. Mossenbock. Escape analysis in the context of dynamic
* compilation and deoptimization. In Proceedings of the International
* Conference on Virtual Execution Environments, pages 111-120, Chicago,
* June 2005
*/
static zend_always_inline void union_find_init(int *parent, int *size, int count) /* {{{ */
{
int i;
for (i = 0; i < count; i++) {
parent[i] = i;
size[i] = 1;
}
}
/* }}} */
static zend_always_inline int union_find_root(int *parent, int i) /* {{{ */
{
int p = parent[i];
while (i != p) {
p = parent[p];
parent[i] = p;
i = p;
p = parent[i];
}
return i;
}
/* }}} */
static zend_always_inline void union_find_unite(int *parent, int *size, int i, int j) /* {{{ */
{
int r1 = union_find_root(parent, i);
int r2 = union_find_root(parent, j);
if (r1 != r2) {
if (size[r1] < size[r2]) {
parent[r1] = r2;
size[r2] += size[r1];
} else {
parent[r2] = r1;
size[r1] += size[r2];
}
}
}
/* }}} */
static zend_result zend_build_equi_escape_sets(int *parent, zend_op_array *op_array, zend_ssa *ssa) /* {{{ */
{
zend_ssa_var *ssa_vars = ssa->vars;
int ssa_vars_count = ssa->vars_count;
zend_ssa_phi *p;
int i, j;
int *size;
ALLOCA_FLAG(use_heap)
size = do_alloca(sizeof(int) * ssa_vars_count, use_heap);
if (!size) {
return FAILURE;
}
union_find_init(parent, size, ssa_vars_count);
for (i = 0; i < ssa_vars_count; i++) {
if (ssa_vars[i].definition_phi) {
p = ssa_vars[i].definition_phi;
if (p->pi >= 0) {
union_find_unite(parent, size, i, p->sources[0]);
} else {
for (j = 0; j < ssa->cfg.blocks[p->block].predecessors_count; j++) {
union_find_unite(parent, size, i, p->sources[j]);
}
}
} else if (ssa_vars[i].definition >= 0) {
int def = ssa_vars[i].definition;
zend_ssa_op *op = ssa->ops + def;
zend_op *opline = op_array->opcodes + def;
if (op->op1_def >= 0) {
if (op->op1_use >= 0) {
if (opline->opcode != ZEND_ASSIGN) {
union_find_unite(parent, size, op->op1_def, op->op1_use);
}
}
if (opline->opcode == ZEND_ASSIGN && op->op2_use >= 0) {
union_find_unite(parent, size, op->op1_def, op->op2_use);
}
}
if (op->op2_def >= 0) {
if (op->op2_use >= 0) {
union_find_unite(parent, size, op->op2_def, op->op2_use);
}
}
if (op->result_def >= 0) {
if (op->result_use >= 0) {
if (opline->opcode != ZEND_QM_ASSIGN) {
union_find_unite(parent, size, op->result_def, op->result_use);
}
}
if (opline->opcode == ZEND_QM_ASSIGN && op->op1_use >= 0) {
union_find_unite(parent, size, op->result_def, op->op1_use);
}
if (opline->opcode == ZEND_ASSIGN && op->op2_use >= 0) {
union_find_unite(parent, size, op->result_def, op->op2_use);
}
if (opline->opcode == ZEND_ASSIGN && op->op1_def >= 0) {
union_find_unite(parent, size, op->result_def, op->op1_def);
}
}
}
}
for (i = 0; i < ssa_vars_count; i++) {
parent[i] = union_find_root(parent, i);
}
free_alloca(size, use_heap);
return SUCCESS;
}
/* }}} */
static bool is_allocation_def(zend_op_array *op_array, zend_ssa *ssa, int def, int var, const zend_script *script) /* {{{ */
{
zend_ssa_op *ssa_op = ssa->ops + def;
zend_op *opline = op_array->opcodes + def;
if (ssa_op->result_def == var) {
switch (opline->opcode) {
case ZEND_INIT_ARRAY:
return 1;
case ZEND_NEW: {
/* objects with destructors should escape */
zend_class_entry *ce = zend_optimizer_get_class_entry_from_op1(
script, op_array, opline);
uint32_t forbidden_flags =
/* These flags will always cause an exception */
ZEND_ACC_IMPLICIT_ABSTRACT_CLASS | ZEND_ACC_EXPLICIT_ABSTRACT_CLASS
| ZEND_ACC_INTERFACE | ZEND_ACC_TRAIT;
if (ce
&& !ce->parent
&& !ce->create_object
&& ce->default_object_handlers->get_constructor == zend_std_get_constructor
&& ce->default_object_handlers->dtor_obj == zend_objects_destroy_object
&& !ce->constructor
&& !ce->destructor
&& !ce->__get
&& !ce->__set
&& !(ce->ce_flags & forbidden_flags)
&& (ce->ce_flags & ZEND_ACC_CONSTANTS_UPDATED)) {
return 1;
}
break;
}
case ZEND_QM_ASSIGN:
if (opline->op1_type == IS_CONST
&& Z_TYPE_P(CRT_CONSTANT(opline->op1)) == IS_ARRAY) {
return 1;
}
if (opline->op1_type == IS_CV && (OP1_INFO() & MAY_BE_ARRAY)) {
return 1;
}
break;
case ZEND_ASSIGN:
if (opline->op1_type == IS_CV && (OP1_INFO() & MAY_BE_ARRAY)) {
return 1;
}
break;
}
} else if (ssa_op->op1_def == var) {
switch (opline->opcode) {
case ZEND_ASSIGN:
if (opline->op2_type == IS_CONST
&& Z_TYPE_P(CRT_CONSTANT(opline->op2)) == IS_ARRAY) {
return 1;
}
if (opline->op2_type == IS_CV && (OP2_INFO() & MAY_BE_ARRAY)) {
return 1;
}
break;
case ZEND_ASSIGN_DIM:
if (OP1_INFO() & (MAY_BE_UNDEF | MAY_BE_NULL | MAY_BE_FALSE)) {
/* implicit object/array allocation */
return 1;
}
break;
}
}
return 0;
}
/* }}} */
static bool is_local_def(zend_op_array *op_array, zend_ssa *ssa, int def, int var, const zend_script *script) /* {{{ */
{
zend_ssa_op *op = ssa->ops + def;
zend_op *opline = op_array->opcodes + def;
if (op->result_def == var) {
switch (opline->opcode) {
case ZEND_INIT_ARRAY:
case ZEND_ADD_ARRAY_ELEMENT:
case ZEND_QM_ASSIGN:
case ZEND_ASSIGN:
return 1;
case ZEND_NEW: {
/* objects with destructors should escape */
zend_class_entry *ce = zend_optimizer_get_class_entry_from_op1(
script, op_array, opline);
if (ce
&& !ce->create_object
&& ce->default_object_handlers->get_constructor == zend_std_get_constructor
&& ce->default_object_handlers->dtor_obj == zend_objects_destroy_object
&& !ce->constructor
&& !ce->destructor
&& !ce->__get
&& !ce->__set
&& !ce->parent) {
return 1;
}
break;
}
}
} else if (op->op1_def == var) {
switch (opline->opcode) {
case ZEND_ASSIGN:
case ZEND_ASSIGN_DIM:
case ZEND_ASSIGN_OBJ:
case ZEND_ASSIGN_OBJ_REF:
case ZEND_ASSIGN_DIM_OP:
case ZEND_ASSIGN_OBJ_OP:
case ZEND_PRE_INC_OBJ:
case ZEND_PRE_DEC_OBJ:
case ZEND_POST_INC_OBJ:
case ZEND_POST_DEC_OBJ:
return 1;
}
}
return 0;
}
/* }}} */
static bool is_escape_use(zend_op_array *op_array, zend_ssa *ssa, int use, int var) /* {{{ */
{
zend_ssa_op *ssa_op = ssa->ops + use;
zend_op *opline = op_array->opcodes + use;
if (ssa_op->op1_use == var) {
switch (opline->opcode) {
case ZEND_ASSIGN:
/* no_val */
break;
case ZEND_QM_ASSIGN:
if (opline->op1_type == IS_CV) {
if (OP1_INFO() & MAY_BE_OBJECT) {
/* object aliasing */
return 1;
}
}
break;
case ZEND_ISSET_ISEMPTY_DIM_OBJ:
case ZEND_ISSET_ISEMPTY_PROP_OBJ:
case ZEND_FETCH_DIM_R:
case ZEND_FETCH_OBJ_R:
case ZEND_FETCH_DIM_IS:
case ZEND_FETCH_OBJ_IS:
break;
case ZEND_ASSIGN_OP:
return 1;
case ZEND_ASSIGN_DIM_OP:
case ZEND_ASSIGN_OBJ_OP:
case ZEND_ASSIGN_STATIC_PROP_OP:
case ZEND_ASSIGN_DIM:
case ZEND_ASSIGN_OBJ:
case ZEND_ASSIGN_OBJ_REF:
break;
case ZEND_PRE_INC_OBJ:
case ZEND_PRE_DEC_OBJ:
case ZEND_POST_INC_OBJ:
case ZEND_POST_DEC_OBJ:
break;
case ZEND_INIT_ARRAY:
case ZEND_ADD_ARRAY_ELEMENT:
if (opline->extended_value & ZEND_ARRAY_ELEMENT_REF) {
return 1;
}
if (OP1_INFO() & MAY_BE_OBJECT) {
/* object aliasing */
return 1;
}
/* reference dependencies processed separately */
break;
case ZEND_OP_DATA:
if ((opline-1)->opcode != ZEND_ASSIGN_DIM
&& (opline-1)->opcode != ZEND_ASSIGN_OBJ) {
return 1;
}
if (OP1_INFO() & MAY_BE_OBJECT) {
/* object aliasing */
return 1;
}
opline--;
ssa_op--;
if (opline->op1_type != IS_CV
|| (OP1_INFO() & MAY_BE_REF)
|| (ssa_op->op1_def >= 0 && ssa->vars[ssa_op->op1_def].alias)) {
/* assignment into escaping structure */
return 1;
}
/* reference dependencies processed separately */
break;
default:
return 1;
}
}
if (ssa_op->op2_use == var) {
switch (opline->opcode) {
case ZEND_ASSIGN:
if (opline->op1_type != IS_CV
|| (OP1_INFO() & MAY_BE_REF)
|| (ssa_op->op1_def >= 0 && ssa->vars[ssa_op->op1_def].alias)) {
/* assignment into escaping variable */
return 1;
}
if (opline->op2_type == IS_CV || opline->result_type != IS_UNUSED) {
if (OP2_INFO() & MAY_BE_OBJECT) {
/* object aliasing */
return 1;
}
}
break;
default:
return 1;
}
}
if (ssa_op->result_use == var) {
switch (opline->opcode) {
case ZEND_ASSIGN:
case ZEND_QM_ASSIGN:
case ZEND_INIT_ARRAY:
case ZEND_ADD_ARRAY_ELEMENT:
break;
default:
return 1;
}
}
return 0;
}
/* }}} */
zend_result zend_ssa_escape_analysis(const zend_script *script, zend_op_array *op_array, zend_ssa *ssa) /* {{{ */
{
zend_ssa_var *ssa_vars = ssa->vars;
int ssa_vars_count = ssa->vars_count;
int i, root, use;
int *ees;
bool has_allocations;
int num_non_escaped;
ALLOCA_FLAG(use_heap)
if (!ssa_vars) {
return SUCCESS;
}
has_allocations = 0;
for (i = op_array->last_var; i < ssa_vars_count; i++) {
if (ssa_vars[i].definition >= 0
&& (ssa->var_info[i].type & (MAY_BE_ARRAY|MAY_BE_OBJECT))
&& is_allocation_def(op_array, ssa, ssa_vars[i].definition, i, script)) {
has_allocations = 1;
break;
}
}
if (!has_allocations) {
return SUCCESS;
}
/* 1. Build EES (Equi-Escape Sets) */
ees = do_alloca(sizeof(int) * ssa_vars_count, use_heap);
if (!ees) {
return FAILURE;
}
if (zend_build_equi_escape_sets(ees, op_array, ssa) == FAILURE) {
free_alloca(ees, use_heap);
return FAILURE;
}
/* 2. Identify Allocations */
num_non_escaped = 0;
for (i = op_array->last_var; i < ssa_vars_count; i++) {
root = ees[i];
if (ssa_vars[root].escape_state > ESCAPE_STATE_NO_ESCAPE) {
/* already escape. skip */
} else if (ssa_vars[i].alias && (ssa->var_info[i].type & MAY_BE_REF)) {
if (ssa_vars[root].escape_state == ESCAPE_STATE_NO_ESCAPE) {
num_non_escaped--;
}
ssa_vars[root].escape_state = ESCAPE_STATE_GLOBAL_ESCAPE;
} else if (ssa_vars[i].definition >= 0
&& (ssa->var_info[i].type & (MAY_BE_ARRAY|MAY_BE_OBJECT))) {
if (!is_local_def(op_array, ssa, ssa_vars[i].definition, i, script)) {
if (ssa_vars[root].escape_state == ESCAPE_STATE_NO_ESCAPE) {
num_non_escaped--;
}
ssa_vars[root].escape_state = ESCAPE_STATE_GLOBAL_ESCAPE;
} else if (ssa_vars[root].escape_state == ESCAPE_STATE_UNKNOWN
&& is_allocation_def(op_array, ssa, ssa_vars[i].definition, i, script)) {
ssa_vars[root].escape_state = ESCAPE_STATE_NO_ESCAPE;
num_non_escaped++;
}
}
}
/* 3. Mark escaped EES */
if (num_non_escaped) {
for (i = 0; i < ssa_vars_count; i++) {
if (ssa_vars[i].use_chain >= 0) {
root = ees[i];
if (ssa_vars[root].escape_state == ESCAPE_STATE_NO_ESCAPE) {
FOREACH_USE(ssa_vars + i, use) {
if (is_escape_use(op_array, ssa, use, i)) {
ssa_vars[root].escape_state = ESCAPE_STATE_GLOBAL_ESCAPE;
num_non_escaped--;
if (num_non_escaped == 0) {
i = ssa_vars_count;
}
break;
}
} FOREACH_USE_END();
}
}
}
}
/* 4. Process referential dependencies */
if (num_non_escaped) {
bool changed;
do {
changed = 0;
for (i = 0; i < ssa_vars_count; i++) {
if (ssa_vars[i].use_chain >= 0) {
root = ees[i];
if (ssa_vars[root].escape_state == ESCAPE_STATE_NO_ESCAPE) {
FOREACH_USE(ssa_vars + i, use) {
zend_ssa_op *op = ssa->ops + use;
zend_op *opline = op_array->opcodes + use;
int enclosing_root;
if (opline->opcode == ZEND_OP_DATA &&
((opline-1)->opcode == ZEND_ASSIGN_DIM ||
(opline-1)->opcode == ZEND_ASSIGN_OBJ ||
(opline-1)->opcode == ZEND_ASSIGN_OBJ_REF) &&
op->op1_use == i &&
(op-1)->op1_use >= 0) {
enclosing_root = ees[(op-1)->op1_use];
} else if ((opline->opcode == ZEND_INIT_ARRAY ||
opline->opcode == ZEND_ADD_ARRAY_ELEMENT) &&
op->op1_use == i &&
op->result_def >= 0) {
enclosing_root = ees[op->result_def];
} else {
continue;
}
if (ssa_vars[enclosing_root].escape_state == ESCAPE_STATE_UNKNOWN ||
ssa_vars[enclosing_root].escape_state > ssa_vars[root].escape_state) {
if (ssa_vars[enclosing_root].escape_state == ESCAPE_STATE_UNKNOWN) {
ssa_vars[root].escape_state = ESCAPE_STATE_GLOBAL_ESCAPE;
} else {
ssa_vars[root].escape_state = ssa_vars[enclosing_root].escape_state;
}
if (ssa_vars[root].escape_state == ESCAPE_STATE_GLOBAL_ESCAPE) {
num_non_escaped--;
if (num_non_escaped == 0) {
changed = 0;
} else {
changed = 1;
}
break;
} else {
changed = 1;
}
}
} FOREACH_USE_END();
}
}
}
} while (changed);
}
/* 5. Propagate values of escape sets to variables */
for (i = 0; i < ssa_vars_count; i++) {
root = ees[i];
if (i != root) {
ssa_vars[i].escape_state = ssa_vars[root].escape_state;
}
}
free_alloca(ees, use_heap);
return SUCCESS;
}
/* }}} */
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