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/*
+----------------------------------------------------------------------+
| Zend Engine, SSA - Static Single Assignment Form |
+----------------------------------------------------------------------+
| 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> |
+----------------------------------------------------------------------+
*/
#ifndef ZEND_SSA_H
#define ZEND_SSA_H
#include "zend_optimizer.h"
#include "zend_cfg.h"
typedef struct _zend_ssa_range {
zend_long min;
zend_long max;
bool underflow;
bool overflow;
} zend_ssa_range;
typedef enum _zend_ssa_negative_lat {
NEG_NONE = 0,
NEG_INIT = 1,
NEG_INVARIANT = 2,
NEG_USE_LT = 3,
NEG_USE_GT = 4,
NEG_UNKNOWN = 5
} zend_ssa_negative_lat;
/* Special kind of SSA Phi function used in eSSA */
typedef struct _zend_ssa_range_constraint {
zend_ssa_range range; /* simple range constraint */
int min_var;
int max_var;
int min_ssa_var; /* ((min_var>0) ? MIN(ssa_var) : 0) + range.min */
int max_ssa_var; /* ((max_var>0) ? MAX(ssa_var) : 0) + range.max */
zend_ssa_negative_lat negative;
} zend_ssa_range_constraint;
typedef struct _zend_ssa_type_constraint {
uint32_t type_mask; /* Type mask to intersect with */
zend_class_entry *ce; /* Class entry for instanceof constraints */
} zend_ssa_type_constraint;
typedef union _zend_ssa_pi_constraint {
zend_ssa_range_constraint range;
zend_ssa_type_constraint type;
} zend_ssa_pi_constraint;
/* SSA Phi - ssa_var = Phi(source0, source1, ...sourceN) */
typedef struct _zend_ssa_phi zend_ssa_phi;
struct _zend_ssa_phi {
zend_ssa_phi *next; /* next Phi in the same BB */
int pi; /* if >= 0 this is actually a e-SSA Pi */
zend_ssa_pi_constraint constraint; /* e-SSA Pi constraint */
int var; /* Original CV, VAR or TMP variable index */
int ssa_var; /* SSA variable index */
int block; /* current BB index */
int visited : 1; /* flag to avoid recursive processing */
int has_range_constraint : 1;
zend_ssa_phi **use_chains;
zend_ssa_phi *sym_use_chain;
int *sources; /* Array of SSA IDs that produce this var.
As many as this block has
predecessors. */
};
typedef struct _zend_ssa_block {
zend_ssa_phi *phis;
} zend_ssa_block;
typedef struct _zend_ssa_op {
int op1_use;
int op2_use;
int result_use;
int op1_def;
int op2_def;
int result_def;
int op1_use_chain;
int op2_use_chain;
int res_use_chain;
} zend_ssa_op;
typedef enum _zend_ssa_alias_kind {
NO_ALIAS,
SYMTABLE_ALIAS,
HTTP_RESPONSE_HEADER_ALIAS
} zend_ssa_alias_kind;
typedef enum _zend_ssa_escape_state {
ESCAPE_STATE_UNKNOWN,
ESCAPE_STATE_NO_ESCAPE,
ESCAPE_STATE_FUNCTION_ESCAPE,
ESCAPE_STATE_GLOBAL_ESCAPE
} zend_ssa_escape_state;
typedef struct _zend_ssa_var {
int var; /* original var number; op.var for CVs and following numbers for VARs and TMP_VARs */
int scc; /* strongly connected component */
int definition; /* opcode that defines this value */
zend_ssa_phi *definition_phi; /* phi that defines this value */
int use_chain; /* uses of this value, linked through opN_use_chain */
zend_ssa_phi *phi_use_chain; /* uses of this value in Phi, linked through use_chain */
zend_ssa_phi *sym_use_chain; /* uses of this value in Pi constraints */
unsigned int no_val : 1; /* value doesn't matter (used as op1 in ZEND_ASSIGN) */
unsigned int scc_entry : 1;
unsigned int alias : 2; /* value may be changed indirectly */
unsigned int escape_state : 2;
} zend_ssa_var;
typedef struct _zend_ssa_var_info {
uint32_t type; /* inferred type (see zend_inference.h) */
zend_ssa_range range;
zend_class_entry *ce;
unsigned int has_range : 1;
unsigned int is_instanceof : 1; /* 0 - class == "ce", 1 - may be child of "ce" */
unsigned int recursive : 1;
unsigned int use_as_double : 1;
unsigned int delayed_fetch_this : 1;
unsigned int avoid_refcounting : 1;
unsigned int guarded_reference : 1;
unsigned int indirect_reference : 1; /* IS_INDIRECT returned by FETCH_DIM_W/FETCH_OBJ_W */
} zend_ssa_var_info;
typedef struct _zend_ssa {
zend_cfg cfg; /* control flow graph */
int vars_count; /* number of SSA variables */
int sccs; /* number of SCCs */
zend_ssa_block *blocks; /* array of SSA blocks */
zend_ssa_op *ops; /* array of SSA instructions */
zend_ssa_var *vars; /* use/def chain of SSA variables */
zend_ssa_var_info *var_info;
} zend_ssa;
BEGIN_EXTERN_C()
ZEND_API int zend_build_ssa(zend_arena **arena, const zend_script *script, const zend_op_array *op_array, uint32_t build_flags, zend_ssa *ssa);
ZEND_API int zend_ssa_compute_use_def_chains(zend_arena **arena, const zend_op_array *op_array, zend_ssa *ssa);
ZEND_API int zend_ssa_rename_op(const zend_op_array *op_array, const zend_op *opline, uint32_t k, uint32_t build_flags, int ssa_vars_count, zend_ssa_op *ssa_ops, int *var);
int zend_ssa_unlink_use_chain(zend_ssa *ssa, int op, int var);
void zend_ssa_remove_predecessor(zend_ssa *ssa, int from, int to);
void zend_ssa_remove_defs_of_instr(zend_ssa *ssa, zend_ssa_op *ssa_op);
void zend_ssa_remove_instr(zend_ssa *ssa, zend_op *opline, zend_ssa_op *ssa_op);
void zend_ssa_remove_phi(zend_ssa *ssa, zend_ssa_phi *phi);
void zend_ssa_remove_uses_of_var(zend_ssa *ssa, int var_num);
void zend_ssa_remove_block(zend_op_array *op_array, zend_ssa *ssa, int b);
void zend_ssa_rename_var_uses(zend_ssa *ssa, int old_var, int new_var, bool update_types);
void zend_ssa_remove_block_from_cfg(zend_ssa *ssa, int b);
static zend_always_inline void _zend_ssa_remove_def(zend_ssa_var *var)
{
ZEND_ASSERT(var->definition >= 0);
ZEND_ASSERT(var->use_chain < 0);
ZEND_ASSERT(!var->phi_use_chain);
var->definition = -1;
}
static zend_always_inline void zend_ssa_remove_result_def(zend_ssa *ssa, zend_ssa_op *ssa_op)
{
zend_ssa_var *var = &ssa->vars[ssa_op->result_def];
_zend_ssa_remove_def(var);
ssa_op->result_def = -1;
}
static zend_always_inline void zend_ssa_remove_op1_def(zend_ssa *ssa, zend_ssa_op *ssa_op)
{
zend_ssa_var *var = &ssa->vars[ssa_op->op1_def];
_zend_ssa_remove_def(var);
ssa_op->op1_def = -1;
}
static zend_always_inline void zend_ssa_remove_op2_def(zend_ssa *ssa, zend_ssa_op *ssa_op)
{
zend_ssa_var *var = &ssa->vars[ssa_op->op2_def];
_zend_ssa_remove_def(var);
ssa_op->op2_def = -1;
}
END_EXTERN_C()
static zend_always_inline int zend_ssa_next_use(const zend_ssa_op *ssa_op, int var, int use)
{
ssa_op += use;
if (ssa_op->op1_use == var) {
return ssa_op->op1_use_chain;
} else if (ssa_op->op2_use == var) {
return ssa_op->op2_use_chain;
} else {
return ssa_op->res_use_chain;
}
}
static zend_always_inline zend_ssa_phi* zend_ssa_next_use_phi(const zend_ssa *ssa, int var, const zend_ssa_phi *p)
{
if (p->pi >= 0) {
return p->use_chains[0];
} else {
int j;
for (j = 0; j < ssa->cfg.blocks[p->block].predecessors_count; j++) {
if (p->sources[j] == var) {
return p->use_chains[j];
}
}
}
return NULL;
}
static zend_always_inline bool zend_ssa_is_no_val_use(const zend_op *opline, const zend_ssa_op *ssa_op, int var)
{
if (opline->opcode == ZEND_ASSIGN
|| opline->opcode == ZEND_UNSET_CV
|| opline->opcode == ZEND_BIND_GLOBAL
|| opline->opcode == ZEND_BIND_STATIC) {
return ssa_op->op1_use == var && ssa_op->op2_use != var;
}
if (opline->opcode == ZEND_FE_FETCH_R || opline->opcode == ZEND_FE_FETCH_RW) {
return ssa_op->op2_use == var && ssa_op->op1_use != var;
}
if (ssa_op->result_use == var
&& opline->opcode != ZEND_ADD_ARRAY_ELEMENT
&& opline->opcode != ZEND_ADD_ARRAY_UNPACK) {
return ssa_op->op1_use != var && ssa_op->op2_use != var;
}
return 0;
}
static zend_always_inline void zend_ssa_rename_defs_of_instr(zend_ssa *ssa, zend_ssa_op *ssa_op) {
/* Rename def to use if possible. Mark variable as not defined otherwise. */
if (ssa_op->op1_def >= 0) {
if (ssa_op->op1_use >= 0) {
zend_ssa_rename_var_uses(ssa, ssa_op->op1_def, ssa_op->op1_use, 1);
}
ssa->vars[ssa_op->op1_def].definition = -1;
ssa_op->op1_def = -1;
}
if (ssa_op->op2_def >= 0) {
if (ssa_op->op2_use >= 0) {
zend_ssa_rename_var_uses(ssa, ssa_op->op2_def, ssa_op->op2_use, 1);
}
ssa->vars[ssa_op->op2_def].definition = -1;
ssa_op->op2_def = -1;
}
if (ssa_op->result_def >= 0) {
if (ssa_op->result_use >= 0) {
zend_ssa_rename_var_uses(ssa, ssa_op->result_def, ssa_op->result_use, 1);
}
ssa->vars[ssa_op->result_def].definition = -1;
ssa_op->result_def = -1;
}
}
#define NUM_PHI_SOURCES(phi) \
((phi)->pi >= 0 ? 1 : (ssa->cfg.blocks[(phi)->block].predecessors_count))
/* FOREACH_USE and FOREACH_PHI_USE explicitly support "continue"
* and changing the use chain of the current element */
#define FOREACH_USE(var, use) do { \
int _var_num = (var) - ssa->vars, next; \
for (use = (var)->use_chain; use >= 0; use = next) { \
next = zend_ssa_next_use(ssa->ops, _var_num, use);
#define FOREACH_USE_END() \
} \
} while (0)
#define FOREACH_PHI_USE(var, phi) do { \
int _var_num = (var) - ssa->vars; \
zend_ssa_phi *next_phi; \
for (phi = (var)->phi_use_chain; phi; phi = next_phi) { \
next_phi = zend_ssa_next_use_phi(ssa, _var_num, phi);
#define FOREACH_PHI_USE_END() \
} \
} while (0)
#define FOREACH_PHI_SOURCE(phi, source) do { \
zend_ssa_phi *_phi = (phi); \
int _i, _end = NUM_PHI_SOURCES(phi); \
for (_i = 0; _i < _end; _i++) { \
ZEND_ASSERT(_phi->sources[_i] >= 0); \
source = _phi->sources[_i];
#define FOREACH_PHI_SOURCE_END() \
} \
} while (0)
#define FOREACH_PHI(phi) do { \
int _i; \
for (_i = 0; _i < ssa->cfg.blocks_count; _i++) { \
phi = ssa->blocks[_i].phis; \
for (; phi; phi = phi->next) {
#define FOREACH_PHI_END() \
} \
} \
} while (0)
#define FOREACH_BLOCK(block) do { \
int _i; \
for (_i = 0; _i < ssa->cfg.blocks_count; _i++) { \
(block) = &ssa->cfg.blocks[_i]; \
if (!((block)->flags & ZEND_BB_REACHABLE)) { \
continue; \
}
#define FOREACH_BLOCK_END() \
} \
} while (0)
/* Does not support "break" */
#define FOREACH_INSTR_NUM(i) do { \
zend_basic_block *_block; \
FOREACH_BLOCK(_block) { \
uint32_t _end = _block->start + _block->len; \
for ((i) = _block->start; (i) < _end; (i)++) {
#define FOREACH_INSTR_NUM_END() \
} \
} FOREACH_BLOCK_END(); \
} while (0)
#endif /* ZEND_SSA_H */