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archived-php-src/Zend/Optimizer/escape_analysis.c
Nikita Popov 83be073abe Move optimizer into core 
This only moves the files, adjusts the build system, exports APIs
and does minor fixups to make sure the code builds.

This does not yet try to make the optimizer usable independently
of opcache.

Closes GH-6642.
2021-01-28 10:38:25 +01:00

540 lines
14 KiB
C
Raw Blame History

/*
+----------------------------------------------------------------------+
| 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: |
| http://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 "php.h"
#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 int 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 inline zend_class_entry *get_class_entry(const zend_script *script, zend_string *lcname) /* {{{ */
{
zend_class_entry *ce = script ? zend_hash_find_ptr(&script->class_table, lcname) : NULL;
if (ce) {
return ce;
}
ce = zend_hash_find_ptr(CG(class_table), lcname);
if (ce && ce->type == ZEND_INTERNAL_CLASS) {
return ce;
}
return NULL;
}
/* }}} */
static int 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 */
if (opline->op1_type == IS_CONST) {
zend_class_entry *ce = get_class_entry(script, Z_STR_P(CRT_CONSTANT(opline->op1)+1));
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->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 int 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 */
if (opline->op1_type == IS_CONST) {
zend_class_entry *ce = get_class_entry(script, Z_STR_P(CRT_CONSTANT(opline->op1)+1));
if (ce && !ce->create_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 int 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;
}
/* }}} */
int 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) != SUCCESS) {
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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