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php-src/Zend/Optimizer/zend_ssa.c
Dmitry Stogov 7496a400aa Fix SSA construction and type inference 
Fixes oss-fuzz #51476
2022-09-19 15:45:34 +03:00

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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> |
| Nikita Popov <nikic@php.net> |
+----------------------------------------------------------------------+
*/
#include "zend_compile.h"
#include "zend_dfg.h"
#include "zend_ssa.h"
#include "zend_dump.h"
#include "zend_inference.h"
#include "Optimizer/zend_optimizer_internal.h"
static bool dominates(const zend_basic_block *blocks, int a, int b) {
while (blocks[b].level > blocks[a].level) {
b = blocks[b].idom;
}
return a == b;
}
static bool will_rejoin(
const zend_cfg *cfg, const zend_dfg *dfg, const zend_basic_block *block,
int other_successor, int exclude, int var) {
int i;
for (i = 0; i < block->predecessors_count; i++) {
int predecessor = cfg->predecessors[block->predecessor_offset + i];
if (predecessor == exclude) {
continue;
}
/* The variable is changed in this predecessor,
* so we will not rejoin with the original value. */
// TODO: This should not be limited to the direct predecessor block.
if (DFG_ISSET(dfg->def, dfg->size, predecessor, var)) {
continue;
}
/* The other successor dominates this predecessor,
* so we will get the original value from it. */
if (dominates(cfg->blocks, other_successor, predecessor)) {
return 1;
}
}
return 0;
}
static bool needs_pi(const zend_op_array *op_array, zend_dfg *dfg, zend_ssa *ssa, int from, int to, int var) /* {{{ */
{
zend_basic_block *from_block, *to_block;
int other_successor;
if (!DFG_ISSET(dfg->in, dfg->size, to, var)) {
/* Variable is not live, certainly won't benefit from pi */
return 0;
}
/* Make sure that both successors of the from block aren't the same. Pi nodes are associated
* with predecessor blocks, so we can't distinguish which edge the pi belongs to. */
from_block = &ssa->cfg.blocks[from];
ZEND_ASSERT(from_block->successors_count == 2);
if (from_block->successors[0] == from_block->successors[1]) {
return 0;
}
to_block = &ssa->cfg.blocks[to];
if (to_block->predecessors_count == 1) {
/* Always place pi if one predecessor (an if branch) */
return 1;
}
/* Check whether we will rejoin with the original value coming from the other successor,
* in which case the pi node will not have an effect. */
other_successor = from_block->successors[0] == to
? from_block->successors[1] : from_block->successors[0];
return !will_rejoin(&ssa->cfg, dfg, to_block, other_successor, from, var);
}
/* }}} */
static zend_ssa_phi *add_pi(
zend_arena **arena, const zend_op_array *op_array, zend_dfg *dfg, zend_ssa *ssa,
int from, int to, int var) /* {{{ */
{
zend_ssa_phi *phi;
if (!needs_pi(op_array, dfg, ssa, from, to, var)) {
return NULL;
}
phi = zend_arena_calloc(arena, 1,
ZEND_MM_ALIGNED_SIZE(sizeof(zend_ssa_phi)) +
ZEND_MM_ALIGNED_SIZE(sizeof(int) * ssa->cfg.blocks[to].predecessors_count) +
sizeof(void*) * ssa->cfg.blocks[to].predecessors_count);
phi->sources = (int*)(((char*)phi) + ZEND_MM_ALIGNED_SIZE(sizeof(zend_ssa_phi)));
memset(phi->sources, 0xff, sizeof(int) * ssa->cfg.blocks[to].predecessors_count);
phi->use_chains = (zend_ssa_phi**)(((char*)phi->sources) + ZEND_MM_ALIGNED_SIZE(sizeof(int) * ssa->cfg.blocks[to].predecessors_count));
phi->pi = from;
phi->var = var;
phi->ssa_var = -1;
phi->next = ssa->blocks[to].phis;
ssa->blocks[to].phis = phi;
/* Block "to" now defines "var" via the pi statement, so add it to the "def" set. Note that
* this is not entirely accurate, because the pi is actually placed along the edge from->to.
* If there is a back-edge to "to" this may result in non-minimal SSA form. */
DFG_SET(dfg->def, dfg->size, to, var);
/* If there are multiple predecessors in the target block, we need to place a phi there.
* However this can (generally) not be expressed in terms of dominance frontiers, so place it
* explicitly. dfg->use here really is dfg->phi, we're reusing the set. */
if (ssa->cfg.blocks[to].predecessors_count > 1) {
DFG_SET(dfg->use, dfg->size, to, var);
}
return phi;
}
/* }}} */
static void pi_range(
zend_ssa_phi *phi, int min_var, int max_var, zend_long min, zend_long max,
char underflow, char overflow, char negative) /* {{{ */
{
zend_ssa_range_constraint *constraint = &phi->constraint.range;
constraint->min_var = min_var;
constraint->max_var = max_var;
constraint->min_ssa_var = -1;
constraint->max_ssa_var = -1;
constraint->range.min = min;
constraint->range.max = max;
constraint->range.underflow = underflow;
constraint->range.overflow = overflow;
constraint->negative = negative ? NEG_INIT : NEG_NONE;
phi->has_range_constraint = 1;
}
/* }}} */
static inline void pi_range_equals(zend_ssa_phi *phi, int var, zend_long val) {
pi_range(phi, var, var, val, val, 0, 0, 0);
}
static inline void pi_range_not_equals(zend_ssa_phi *phi, int var, zend_long val) {
pi_range(phi, var, var, val, val, 0, 0, 1);
}
static inline void pi_range_min(zend_ssa_phi *phi, int var, zend_long val) {
pi_range(phi, var, -1, val, ZEND_LONG_MAX, 0, 1, 0);
}
static inline void pi_range_max(zend_ssa_phi *phi, int var, zend_long val) {
pi_range(phi, -1, var, ZEND_LONG_MIN, val, 1, 0, 0);
}
static void pi_type_mask(zend_ssa_phi *phi, uint32_t type_mask) {
phi->has_range_constraint = 0;
phi->constraint.type.ce = NULL;
phi->constraint.type.type_mask = MAY_BE_REF|MAY_BE_RC1|MAY_BE_RCN;
phi->constraint.type.type_mask |= type_mask;
if (type_mask & MAY_BE_NULL) {
phi->constraint.type.type_mask |= MAY_BE_UNDEF;
}
}
static inline void pi_not_type_mask(zend_ssa_phi *phi, uint32_t type_mask) {
uint32_t relevant = MAY_BE_ANY|MAY_BE_ARRAY_KEY_ANY|MAY_BE_ARRAY_OF_ANY|MAY_BE_ARRAY_OF_REF;
pi_type_mask(phi, ~type_mask & relevant);
}
static inline uint32_t mask_for_type_check(uint32_t type) {
if (type & MAY_BE_ARRAY) {
return type | (MAY_BE_ARRAY_KEY_ANY|MAY_BE_ARRAY_OF_ANY|MAY_BE_ARRAY_OF_REF);
} else {
return type;
}
}
/* We can interpret $a + 5 == 0 as $a = 0 - 5, i.e. shift the adjustment to the other operand.
* This negated adjustment is what is written into the "adjustment" parameter. */
static int find_adjusted_tmp_var(const zend_op_array *op_array, uint32_t build_flags, zend_op *opline, uint32_t var_num, zend_long *adjustment) /* {{{ */
{
zend_op *op = opline;
zval *zv;
while (op != op_array->opcodes) {
op--;
if (op->result_type != IS_TMP_VAR || op->result.var != var_num) {
continue;
}
if (op->opcode == ZEND_POST_DEC) {
if (op->op1_type == IS_CV) {
*adjustment = -1;
return EX_VAR_TO_NUM(op->op1.var);
}
} else if (op->opcode == ZEND_POST_INC) {
if (op->op1_type == IS_CV) {
*adjustment = 1;
return EX_VAR_TO_NUM(op->op1.var);
}
} else if (op->opcode == ZEND_ADD) {
if (op->op1_type == IS_CV && op->op2_type == IS_CONST) {
zv = CRT_CONSTANT_EX(op_array, op, op->op2);
if (Z_TYPE_P(zv) == IS_LONG
&& Z_LVAL_P(zv) != ZEND_LONG_MIN) {
*adjustment = -Z_LVAL_P(zv);
return EX_VAR_TO_NUM(op->op1.var);
}
} else if (op->op2_type == IS_CV && op->op1_type == IS_CONST) {
zv = CRT_CONSTANT_EX(op_array, op, op->op1);
if (Z_TYPE_P(zv) == IS_LONG
&& Z_LVAL_P(zv) != ZEND_LONG_MIN) {
*adjustment = -Z_LVAL_P(zv);
return EX_VAR_TO_NUM(op->op2.var);
}
}
} else if (op->opcode == ZEND_SUB) {
if (op->op1_type == IS_CV && op->op2_type == IS_CONST) {
zv = CRT_CONSTANT_EX(op_array, op, op->op2);
if (Z_TYPE_P(zv) == IS_LONG) {
*adjustment = Z_LVAL_P(zv);
return EX_VAR_TO_NUM(op->op1.var);
}
}
}
break;
}
return -1;
}
/* }}} */
/* e-SSA construction: Pi placement (Pi is actually a Phi with single
* source and constraint).
* Order of Phis is important, Pis must be placed before Phis
*/
static void place_essa_pis(
zend_arena **arena, const zend_script *script, const zend_op_array *op_array,
uint32_t build_flags, zend_ssa *ssa, zend_dfg *dfg) /* {{{ */ {
zend_basic_block *blocks = ssa->cfg.blocks;
int j, blocks_count = ssa->cfg.blocks_count;
for (j = 0; j < blocks_count; j++) {
zend_ssa_phi *pi;
zend_op *opline = op_array->opcodes + blocks[j].start + blocks[j].len - 1;
int bt; /* successor block number if a condition is true */
int bf; /* successor block number if a condition is false */
if ((blocks[j].flags & ZEND_BB_REACHABLE) == 0 || blocks[j].len == 0) {
continue;
}
/* the last instruction of basic block is conditional branch,
* based on comparison of CV(s)
*/
switch (opline->opcode) {
case ZEND_JMPZ:
bf = blocks[j].successors[0];
bt = blocks[j].successors[1];
break;
case ZEND_JMPNZ:
bt = blocks[j].successors[0];
bf = blocks[j].successors[1];
break;
case ZEND_COALESCE:
if (opline->op1_type == IS_CV) {
int var = EX_VAR_TO_NUM(opline->op1.var);
if ((pi = add_pi(arena, op_array, dfg, ssa, j, blocks[j].successors[0], var))) {
pi_not_type_mask(pi, MAY_BE_NULL);
}
}
continue;
case ZEND_JMP_NULL:
if (opline->op1_type == IS_CV) {
int var = EX_VAR_TO_NUM(opline->op1.var);
if ((pi = add_pi(arena, op_array, dfg, ssa, j, blocks[j].successors[1], var))) {
pi_not_type_mask(pi, MAY_BE_NULL);
}
}
continue;
default:
continue;
}
/* The following patterns all inspect the opline directly before the JMPZ opcode.
* Make sure that it is part of the same block, otherwise it might not be a dominating
* assignment. */
if (blocks[j].len == 1) {
continue;
}
if (opline->op1_type == IS_TMP_VAR &&
((opline-1)->opcode == ZEND_IS_EQUAL ||
(opline-1)->opcode == ZEND_IS_NOT_EQUAL ||
(opline-1)->opcode == ZEND_IS_SMALLER ||
(opline-1)->opcode == ZEND_IS_SMALLER_OR_EQUAL) &&
opline->op1.var == (opline-1)->result.var) {
int var1 = -1;
int var2 = -1;
zend_long val1 = 0;
zend_long val2 = 0;
// long val = 0;
if ((opline-1)->op1_type == IS_CV) {
var1 = EX_VAR_TO_NUM((opline-1)->op1.var);
} else if ((opline-1)->op1_type == IS_TMP_VAR) {
var1 = find_adjusted_tmp_var(
op_array, build_flags, opline, (opline-1)->op1.var, &val2);
}
if ((opline-1)->op2_type == IS_CV) {
var2 = EX_VAR_TO_NUM((opline-1)->op2.var);
} else if ((opline-1)->op2_type == IS_TMP_VAR) {
var2 = find_adjusted_tmp_var(
op_array, build_flags, opline, (opline-1)->op2.var, &val1);
}
if (var1 >= 0 && var2 >= 0) {
if (!zend_sub_will_overflow(val1, val2) && !zend_sub_will_overflow(val2, val1)) {
zend_long tmp = val1;
val1 -= val2;
val2 -= tmp;
} else {
var1 = -1;
var2 = -1;
}
} else if (var1 >= 0 && var2 < 0) {
zend_long add_val2 = 0;
if ((opline-1)->op2_type == IS_CONST) {
zval *zv = CRT_CONSTANT_EX(op_array, (opline-1), (opline-1)->op2);
if (Z_TYPE_P(zv) == IS_LONG) {
add_val2 = Z_LVAL_P(zv);
} else {
var1 = -1;
}
} else {
var1 = -1;
}
if (!zend_add_will_overflow(val2, add_val2)) {
val2 += add_val2;
} else {
var1 = -1;
}
} else if (var1 < 0 && var2 >= 0) {
zend_long add_val1 = 0;
if ((opline-1)->op1_type == IS_CONST) {
zval *zv = CRT_CONSTANT_EX(op_array, (opline-1), (opline-1)->op1);
if (Z_TYPE_P(zv) == IS_LONG) {
add_val1 = Z_LVAL_P(CRT_CONSTANT_EX(op_array, (opline-1), (opline-1)->op1));
} else {
var2 = -1;
}
} else {
var2 = -1;
}
if (!zend_add_will_overflow(val1, add_val1)) {
val1 += add_val1;
} else {
var2 = -1;
}
}
if (var1 >= 0) {
if ((opline-1)->opcode == ZEND_IS_EQUAL) {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var1))) {
pi_range_equals(pi, var2, val2);
}
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var1))) {
pi_range_not_equals(pi, var2, val2);
}
} else if ((opline-1)->opcode == ZEND_IS_NOT_EQUAL) {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var1))) {
pi_range_equals(pi, var2, val2);
}
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var1))) {
pi_range_not_equals(pi, var2, val2);
}
} else if ((opline-1)->opcode == ZEND_IS_SMALLER) {
if (val2 > ZEND_LONG_MIN) {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var1))) {
pi_range_max(pi, var2, val2-1);
}
}
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var1))) {
pi_range_min(pi, var2, val2);
}
} else if ((opline-1)->opcode == ZEND_IS_SMALLER_OR_EQUAL) {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var1))) {
pi_range_max(pi, var2, val2);
}
if (val2 < ZEND_LONG_MAX) {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var1))) {
pi_range_min(pi, var2, val2+1);
}
}
}
}
if (var2 >= 0) {
if((opline-1)->opcode == ZEND_IS_EQUAL) {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var2))) {
pi_range_equals(pi, var1, val1);
}
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var2))) {
pi_range_not_equals(pi, var1, val1);
}
} else if ((opline-1)->opcode == ZEND_IS_NOT_EQUAL) {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var2))) {
pi_range_equals(pi, var1, val1);
}
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var2))) {
pi_range_not_equals(pi, var1, val1);
}
} else if ((opline-1)->opcode == ZEND_IS_SMALLER) {
if (val1 < ZEND_LONG_MAX) {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var2))) {
pi_range_min(pi, var1, val1+1);
}
}
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var2))) {
pi_range_max(pi, var1, val1);
}
} else if ((opline-1)->opcode == ZEND_IS_SMALLER_OR_EQUAL) {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var2))) {
pi_range_min(pi, var1, val1);
}
if (val1 > ZEND_LONG_MIN) {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var2))) {
pi_range_max(pi, var1, val1-1);
}
}
}
}
} else if (opline->op1_type == IS_TMP_VAR &&
((opline-1)->opcode == ZEND_POST_INC ||
(opline-1)->opcode == ZEND_POST_DEC) &&
opline->op1.var == (opline-1)->result.var &&
(opline-1)->op1_type == IS_CV) {
int var = EX_VAR_TO_NUM((opline-1)->op1.var);
if ((opline-1)->opcode == ZEND_POST_DEC) {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var))) {
pi_range_equals(pi, -1, -1);
}
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var))) {
pi_range_not_equals(pi, -1, -1);
}
} else if ((opline-1)->opcode == ZEND_POST_INC) {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var))) {
pi_range_equals(pi, -1, 1);
}
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var))) {
pi_range_not_equals(pi, -1, 1);
}
}
} else if (opline->op1_type == IS_TMP_VAR &&
((opline-1)->opcode == ZEND_PRE_INC ||
(opline-1)->opcode == ZEND_PRE_DEC) &&
opline->op1.var == (opline-1)->result.var &&
(opline-1)->op1_type == IS_CV) {
int var = EX_VAR_TO_NUM((opline-1)->op1.var);
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var))) {
pi_range_equals(pi, -1, 0);
}
/* speculative */
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var))) {
pi_range_not_equals(pi, -1, 0);
}
} else if (opline->op1_type == IS_TMP_VAR && (opline-1)->opcode == ZEND_TYPE_CHECK &&
opline->op1.var == (opline-1)->result.var && (opline-1)->op1_type == IS_CV) {
int var = EX_VAR_TO_NUM((opline-1)->op1.var);
uint32_t type = (opline-1)->extended_value;
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var))) {
pi_type_mask(pi, mask_for_type_check(type));
}
if (type != MAY_BE_RESOURCE) {
/* is_resource() may return false for closed resources */
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var))) {
pi_not_type_mask(pi, mask_for_type_check(type));
}
}
} else if (opline->op1_type == IS_TMP_VAR &&
((opline-1)->opcode == ZEND_IS_IDENTICAL
|| (opline-1)->opcode == ZEND_IS_NOT_IDENTICAL) &&
opline->op1.var == (opline-1)->result.var) {
int var;
zval *val;
uint32_t type_mask;
if ((opline-1)->op1_type == IS_CV && (opline-1)->op2_type == IS_CONST) {
var = EX_VAR_TO_NUM((opline-1)->op1.var);
val = CRT_CONSTANT_EX(op_array, (opline-1), (opline-1)->op2);
} else if ((opline-1)->op1_type == IS_CONST && (opline-1)->op2_type == IS_CV) {
var = EX_VAR_TO_NUM((opline-1)->op2.var);
val = CRT_CONSTANT_EX(op_array, (opline-1), (opline-1)->op1);
} else {
continue;
}
/* We're interested in === null/true/false comparisons here, because they eliminate
* a type in the false-branch. Other === VAL comparisons are unlikely to be useful. */
if (Z_TYPE_P(val) != IS_NULL && Z_TYPE_P(val) != IS_TRUE && Z_TYPE_P(val) != IS_FALSE) {
continue;
}
type_mask = _const_op_type(val);
if ((opline-1)->opcode == ZEND_IS_IDENTICAL) {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var))) {
pi_type_mask(pi, type_mask);
}
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var))) {
pi_not_type_mask(pi, type_mask);
}
} else {
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bf, var))) {
pi_type_mask(pi, type_mask);
}
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var))) {
pi_not_type_mask(pi, type_mask);
}
}
} else if (opline->op1_type == IS_TMP_VAR && (opline-1)->opcode == ZEND_INSTANCEOF &&
opline->op1.var == (opline-1)->result.var && (opline-1)->op1_type == IS_CV &&
(opline-1)->op2_type == IS_CONST) {
int var = EX_VAR_TO_NUM((opline-1)->op1.var);
zend_string *lcname = Z_STR_P(CRT_CONSTANT_EX(op_array, (opline-1), (opline-1)->op2) + 1);
zend_class_entry *ce = zend_optimizer_get_class_entry(script, op_array, lcname);
if (!ce) {
continue;
}
if ((pi = add_pi(arena, op_array, dfg, ssa, j, bt, var))) {
pi_type_mask(pi, MAY_BE_OBJECT);
pi->constraint.type.ce = ce;
}
}
}
}
/* }}} */
static zend_always_inline 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) /* {{{ */
{
const zend_op *next;
if (opline->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
ssa_ops[k].op1_use = var[EX_VAR_TO_NUM(opline->op1.var)];
//USE_SSA_VAR(op_array->last_var + opline->op1.var)
}
if (opline->op2_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
ssa_ops[k].op2_use = var[EX_VAR_TO_NUM(opline->op2.var)];
//USE_SSA_VAR(op_array->last_var + opline->op2.var)
}
if ((build_flags & ZEND_SSA_USE_CV_RESULTS)
&& opline->result_type == IS_CV
&& opline->opcode != ZEND_RECV) {
ssa_ops[k].result_use = var[EX_VAR_TO_NUM(opline->result.var)];
//USE_SSA_VAR(op_array->last_var + opline->result.var)
}
switch (opline->opcode) {
case ZEND_ASSIGN:
if ((build_flags & ZEND_SSA_RC_INFERENCE) && opline->op2_type == IS_CV) {
ssa_ops[k].op2_def = ssa_vars_count;
var[EX_VAR_TO_NUM(opline->op2.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(opline->op2.var)
}
if (opline->op1_type == IS_CV) {
add_op1_def:
ssa_ops[k].op1_def = ssa_vars_count;
var[EX_VAR_TO_NUM(opline->op1.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(opline->op1.var)
}
break;
case ZEND_ASSIGN_REF:
if (opline->op2_type == IS_CV) {
ssa_ops[k].op2_def = ssa_vars_count;
var[EX_VAR_TO_NUM(opline->op2.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(opline->op2.var)
}
if (opline->op1_type == IS_CV) {
goto add_op1_def;
}
break;
case ZEND_ASSIGN_DIM:
case ZEND_ASSIGN_OBJ:
next = opline + 1;
if (next->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
ssa_ops[k + 1].op1_use = var[EX_VAR_TO_NUM(next->op1.var)];
//USE_SSA_VAR(op_array->last_var + next->op1.var);
if (build_flags & ZEND_SSA_RC_INFERENCE && next->op1_type == IS_CV) {
ssa_ops[k + 1].op1_def = ssa_vars_count;
var[EX_VAR_TO_NUM(next->op1.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(next->op1.var)
}
}
if (opline->op1_type == IS_CV) {
ssa_ops[k].op1_def = ssa_vars_count;
var[EX_VAR_TO_NUM(opline->op1.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(opline->op1.var)
}
break;
case ZEND_ASSIGN_OBJ_REF:
if (opline->op1_type == IS_CV) {
ssa_ops[k].op1_def = ssa_vars_count;
var[EX_VAR_TO_NUM(opline->op1.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(opline->op1.var)
}
next = opline + 1;
if (next->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
ssa_ops[k + 1].op1_use = var[EX_VAR_TO_NUM(next->op1.var)];
//USE_SSA_VAR(op_array->last_var + next->op1.var);
if (next->op1_type == IS_CV) {
ssa_ops[k + 1].op1_def = ssa_vars_count;
var[EX_VAR_TO_NUM(next->op1.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(next->op1.var)
}
}
break;
case ZEND_ASSIGN_STATIC_PROP:
next = opline + 1;
if (next->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
ssa_ops[k + 1].op1_use = var[EX_VAR_TO_NUM(next->op1.var)];
//USE_SSA_VAR(op_array->last_var + next->op1.var);
if ((build_flags & ZEND_SSA_RC_INFERENCE) && next->op1_type == IS_CV) {
ssa_ops[k + 1].op1_def = ssa_vars_count;
var[EX_VAR_TO_NUM(next->op1.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(next->op1.var)
}
}
break;
case ZEND_ASSIGN_STATIC_PROP_REF:
next = opline + 1;
if (next->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
ssa_ops[k + 1].op1_use = var[EX_VAR_TO_NUM(next->op1.var)];
//USE_SSA_VAR(op_array->last_var + next->op1.var);
if (next->op1_type == IS_CV) {
ssa_ops[k + 1].op1_def = ssa_vars_count;
var[EX_VAR_TO_NUM(next->op1.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(next->op1.var)
}
}
break;
case ZEND_ASSIGN_STATIC_PROP_OP:
next = opline + 1;
if (next->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
ssa_ops[k + 1].op1_use = var[EX_VAR_TO_NUM(next->op1.var)];
//USE_SSA_VAR(op_array->last_var + next->op1.var);
}
break;
case ZEND_ASSIGN_DIM_OP:
case ZEND_ASSIGN_OBJ_OP:
if (opline->op1_type == IS_CV) {
ssa_ops[k].op1_def = ssa_vars_count;
var[EX_VAR_TO_NUM(opline->op1.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(opline->op1.var)
}
next = opline + 1;
if (next->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
ssa_ops[k + 1].op1_use = var[EX_VAR_TO_NUM(next->op1.var)];
//USE_SSA_VAR(op_array->last_var + next->op1.var);
}
break;
case ZEND_ASSIGN_OP:
case ZEND_PRE_INC:
case ZEND_PRE_DEC:
case ZEND_POST_INC:
case ZEND_POST_DEC:
case ZEND_BIND_GLOBAL:
case ZEND_BIND_STATIC:
case ZEND_SEND_VAR_NO_REF:
case ZEND_SEND_VAR_NO_REF_EX:
case ZEND_SEND_VAR_EX:
case ZEND_SEND_FUNC_ARG:
case ZEND_SEND_REF:
case ZEND_SEND_UNPACK:
case ZEND_FE_RESET_RW:
case ZEND_MAKE_REF:
case ZEND_PRE_INC_OBJ:
case ZEND_PRE_DEC_OBJ:
case ZEND_POST_INC_OBJ:
case ZEND_POST_DEC_OBJ:
case ZEND_UNSET_DIM:
case ZEND_UNSET_OBJ:
case ZEND_FETCH_DIM_W:
case ZEND_FETCH_DIM_RW:
case ZEND_FETCH_DIM_FUNC_ARG:
case ZEND_FETCH_DIM_UNSET:
case ZEND_FETCH_LIST_W:
if (opline->op1_type == IS_CV) {
goto add_op1_def;
}
break;
case ZEND_SEND_VAR:
case ZEND_CAST:
case ZEND_QM_ASSIGN:
case ZEND_JMP_SET:
case ZEND_COALESCE:
case ZEND_FE_RESET_R:
if ((build_flags & ZEND_SSA_RC_INFERENCE) && opline->op1_type == IS_CV) {
goto add_op1_def;
}
break;
case ZEND_ADD_ARRAY_UNPACK:
ssa_ops[k].result_use = var[EX_VAR_TO_NUM(opline->result.var)];
break;
case ZEND_ADD_ARRAY_ELEMENT:
ssa_ops[k].result_use = var[EX_VAR_TO_NUM(opline->result.var)];
ZEND_FALLTHROUGH;
case ZEND_INIT_ARRAY:
if (((build_flags & ZEND_SSA_RC_INFERENCE)
|| (opline->extended_value & ZEND_ARRAY_ELEMENT_REF))
&& opline->op1_type == IS_CV) {
goto add_op1_def;
}
break;
case ZEND_YIELD:
if (opline->op1_type == IS_CV
&& ((op_array->fn_flags & ZEND_ACC_RETURN_REFERENCE)
|| (build_flags & ZEND_SSA_RC_INFERENCE))) {
goto add_op1_def;
}
break;
case ZEND_UNSET_CV:
goto add_op1_def;
case ZEND_VERIFY_RETURN_TYPE:
if (opline->op1_type & (IS_TMP_VAR|IS_VAR|IS_CV)) {
goto add_op1_def;
}
break;
case ZEND_FE_FETCH_R:
case ZEND_FE_FETCH_RW:
if (opline->op2_type != IS_CV) {
ssa_ops[k].op2_use = -1; /* not used */
}
ssa_ops[k].op2_def = ssa_vars_count;
var[EX_VAR_TO_NUM(opline->op2.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(opline->op2.var)
break;
case ZEND_BIND_LEXICAL:
if ((opline->extended_value & ZEND_BIND_REF) || (build_flags & ZEND_SSA_RC_INFERENCE)) {
ssa_ops[k].op2_def = ssa_vars_count;
var[EX_VAR_TO_NUM(opline->op2.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(opline->op2.var)
}
break;
case ZEND_COPY_TMP:
if (build_flags & ZEND_SSA_RC_INFERENCE) {
ssa_ops[k].op1_def = ssa_vars_count;
var[EX_VAR_TO_NUM(opline->op1.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(opline->op1.var)
}
break;
default:
break;
}
if (opline->result_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
ssa_ops[k].result_def = ssa_vars_count;
var[EX_VAR_TO_NUM(opline->result.var)] = ssa_vars_count;
ssa_vars_count++;
//NEW_SSA_VAR(op_array->last_var + opline->result.var)
}
return ssa_vars_count;
}
/* }}} */
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) /* {{{ */
{
return _zend_ssa_rename_op(op_array, opline, k, build_flags, ssa_vars_count, ssa_ops, var);
}
/* }}} */
static zend_result zend_ssa_rename(const zend_op_array *op_array, uint32_t build_flags, zend_ssa *ssa, int *var, int n) /* {{{ */
{
zend_basic_block *blocks = ssa->cfg.blocks;
zend_ssa_block *ssa_blocks = ssa->blocks;
zend_ssa_op *ssa_ops = ssa->ops;
int ssa_vars_count = ssa->vars_count;
int i, j;
zend_op *opline, *end;
int *tmp = NULL;
ALLOCA_FLAG(use_heap = 0);
// FIXME: Can we optimize this copying out in some cases?
if (blocks[n].next_child >= 0) {
tmp = do_alloca(sizeof(int) * (op_array->last_var + op_array->T), use_heap);
memcpy(tmp, var, sizeof(int) * (op_array->last_var + op_array->T));
var = tmp;
}
if (ssa_blocks[n].phis) {
zend_ssa_phi *phi = ssa_blocks[n].phis;
do {
if (phi->ssa_var < 0) {
phi->ssa_var = ssa_vars_count;
var[phi->var] = ssa_vars_count;
ssa_vars_count++;
} else {
var[phi->var] = phi->ssa_var;
}
phi = phi->next;
} while (phi);
}
opline = op_array->opcodes + blocks[n].start;
end = opline + blocks[n].len;
for (; opline < end; opline++) {
uint32_t k = opline - op_array->opcodes;
if (opline->opcode != ZEND_OP_DATA) {
ssa_vars_count = _zend_ssa_rename_op(op_array, opline, k, build_flags, ssa_vars_count, ssa_ops, var);
}
}
zend_ssa_op *fe_fetch_ssa_op = blocks[n].len != 0
&& ((end-1)->opcode == ZEND_FE_FETCH_R || (end-1)->opcode == ZEND_FE_FETCH_RW)
&& (end-1)->op2_type == IS_CV
? &ssa_ops[blocks[n].start + blocks[n].len - 1] : NULL;
for (i = 0; i < blocks[n].successors_count; i++) {
int succ = blocks[n].successors[i];
zend_ssa_phi *p;
for (p = ssa_blocks[succ].phis; p; p = p->next) {
if (p->pi == n) {
/* e-SSA Pi */
if (p->has_range_constraint) {
if (p->constraint.range.min_var >= 0) {
p->constraint.range.min_ssa_var = var[p->constraint.range.min_var];
}
if (p->constraint.range.max_var >= 0) {
p->constraint.range.max_ssa_var = var[p->constraint.range.max_var];
}
}
for (j = 0; j < blocks[succ].predecessors_count; j++) {
p->sources[j] = var[p->var];
}
if (p->ssa_var < 0) {
p->ssa_var = ssa_vars_count;
ssa_vars_count++;
}
} else if (p->pi < 0) {
/* Normal Phi */
for (j = 0; j < blocks[succ].predecessors_count; j++)
if (ssa->cfg.predecessors[blocks[succ].predecessor_offset + j] == n) {
break;
}
ZEND_ASSERT(j < blocks[succ].predecessors_count);
p->sources[j] = var[p->var];
if (fe_fetch_ssa_op && i == 0 && p->sources[j] == fe_fetch_ssa_op->op2_def) {
/* On the exit edge of an FE_FETCH, use the pre-modification value instead. */
p->sources[j] = fe_fetch_ssa_op->op2_use;
}
}
}
for (p = ssa_blocks[succ].phis; p && (p->pi >= 0); p = p->next) {
if (p->pi == n) {
zend_ssa_phi *q = p->next;
while (q) {
if (q->pi < 0 && q->var == p->var) {
for (j = 0; j < blocks[succ].predecessors_count; j++) {
if (ssa->cfg.predecessors[blocks[succ].predecessor_offset + j] == n) {
break;
}
}
ZEND_ASSERT(j < blocks[succ].predecessors_count);
q->sources[j] = p->ssa_var;
}
q = q->next;
}
}
}
}
ssa->vars_count = ssa_vars_count;
j = blocks[n].children;
while (j >= 0) {
// FIXME: Tail call optimization?
if (zend_ssa_rename(op_array, build_flags, ssa, var, j) == FAILURE)
return FAILURE;
j = blocks[j].next_child;
}
if (tmp) {
free_alloca(tmp, use_heap);
}
return SUCCESS;
}
/* }}} */
ZEND_API zend_result zend_build_ssa(zend_arena **arena, const zend_script *script, const zend_op_array *op_array, uint32_t build_flags, zend_ssa *ssa) /* {{{ */
{
zend_basic_block *blocks = ssa->cfg.blocks;
zend_ssa_block *ssa_blocks;
int blocks_count = ssa->cfg.blocks_count;
uint32_t set_size;
zend_bitset def, in, phi;
int *var = NULL;
int i, j, k, changed;
zend_dfg dfg;
ALLOCA_FLAG(dfg_use_heap)
ALLOCA_FLAG(var_use_heap)
if ((blocks_count * (op_array->last_var + op_array->T)) > 4 * 1024 * 1024) {
/* Don't build SSA for very big functions */
return FAILURE;
}
ssa_blocks = zend_arena_calloc(arena, blocks_count, sizeof(zend_ssa_block));
ssa->blocks = ssa_blocks;
/* Compute Variable Liveness */
dfg.vars = op_array->last_var + op_array->T;
dfg.size = set_size = zend_bitset_len(dfg.vars);
dfg.tmp = do_alloca((set_size * sizeof(zend_ulong)) * (blocks_count * 4 + 1), dfg_use_heap);
memset(dfg.tmp, 0, (set_size * sizeof(zend_ulong)) * (blocks_count * 4 + 1));
dfg.def = dfg.tmp + set_size;
dfg.use = dfg.def + set_size * blocks_count;
dfg.in = dfg.use + set_size * blocks_count;
dfg.out = dfg.in + set_size * blocks_count;
zend_build_dfg(op_array, &ssa->cfg, &dfg, build_flags);
if (build_flags & ZEND_SSA_DEBUG_LIVENESS) {
zend_dump_dfg(op_array, &ssa->cfg, &dfg);
}
def = dfg.def;
in = dfg.in;
/* Reuse the "use" set, as we no longer need it */
phi = dfg.use;
zend_bitset_clear(phi, set_size * blocks_count);
/* Place e-SSA pis. This will add additional "def" points, so it must
* happen before def propagation. */
place_essa_pis(arena, script, op_array, build_flags, ssa, &dfg);
/* SSA construction, Step 1: Propagate "def" sets in merge points */
do {
changed = 0;
for (j = 0; j < blocks_count; j++) {
zend_bitset def_j = def + j * set_size, phi_j = phi + j * set_size;
if ((blocks[j].flags & ZEND_BB_REACHABLE) == 0) {
continue;
}
if (blocks[j].predecessors_count > 1) {
if (blocks[j].flags & ZEND_BB_IRREDUCIBLE_LOOP) {
/* Prevent any values from flowing into irreducible loops by
replacing all incoming values with explicit phis. The
register allocator depends on this property. */
zend_bitset_union(phi_j, in + (j * set_size), set_size);
} else {
for (k = 0; k < blocks[j].predecessors_count; k++) {
i = ssa->cfg.predecessors[blocks[j].predecessor_offset + k];
while (i != -1 && i != blocks[j].idom) {
zend_bitset_union_with_intersection(
phi_j, phi_j, def + (i * set_size), in + (j * set_size), set_size);
i = blocks[i].idom;
}
}
}
if (!zend_bitset_subset(phi_j, def_j, set_size)) {
zend_bitset_union(def_j, phi_j, set_size);
changed = 1;
}
}
}
} while (changed);
/* SSA construction, Step 2: Phi placement based on Dominance Frontiers */
var = do_alloca(sizeof(int) * (op_array->last_var + op_array->T), var_use_heap);
if (!var) {
free_alloca(dfg.tmp, dfg_use_heap);
return FAILURE;
}
for (j = 0; j < blocks_count; j++) {
if ((blocks[j].flags & ZEND_BB_REACHABLE) == 0) {
continue;
}
if (!zend_bitset_empty(phi + j * set_size, set_size)) {
ZEND_BITSET_REVERSE_FOREACH(phi + j * set_size, set_size, i) {
zend_ssa_phi *phi = zend_arena_calloc(arena, 1,
ZEND_MM_ALIGNED_SIZE(sizeof(zend_ssa_phi)) +
ZEND_MM_ALIGNED_SIZE(sizeof(int) * blocks[j].predecessors_count) +
sizeof(void*) * blocks[j].predecessors_count);
phi->sources = (int*)(((char*)phi) + ZEND_MM_ALIGNED_SIZE(sizeof(zend_ssa_phi)));
memset(phi->sources, 0xff, sizeof(int) * blocks[j].predecessors_count);
phi->use_chains = (zend_ssa_phi**)(((char*)phi->sources) + ZEND_MM_ALIGNED_SIZE(sizeof(int) * ssa->cfg.blocks[j].predecessors_count));
phi->pi = -1;
phi->var = i;
phi->ssa_var = -1;
/* Place phis after pis */
{
zend_ssa_phi **pp = &ssa_blocks[j].phis;
while (*pp) {
if ((*pp)->pi < 0) {
break;
}
pp = &(*pp)->next;
}
phi->next = *pp;
*pp = phi;
}
} ZEND_BITSET_FOREACH_END();
}
}
if (build_flags & ZEND_SSA_DEBUG_PHI_PLACEMENT) {
zend_dump_phi_placement(op_array, ssa);
}
/* SSA construction, Step 3: Renaming */
ssa->ops = zend_arena_calloc(arena, op_array->last, sizeof(zend_ssa_op));
memset(ssa->ops, 0xff, op_array->last * sizeof(zend_ssa_op));
memset(var + op_array->last_var, 0xff, op_array->T * sizeof(int));
/* Create uninitialized SSA variables for each CV */
for (j = 0; j < op_array->last_var; j++) {
var[j] = j;
}
ssa->vars_count = op_array->last_var;
if (zend_ssa_rename(op_array, build_flags, ssa, var, 0) == FAILURE) {
free_alloca(var, var_use_heap);
free_alloca(dfg.tmp, dfg_use_heap);
return FAILURE;
}
free_alloca(var, var_use_heap);
free_alloca(dfg.tmp, dfg_use_heap);
return SUCCESS;
}
/* }}} */
ZEND_API void zend_ssa_compute_use_def_chains(zend_arena **arena, const zend_op_array *op_array, zend_ssa *ssa) /* {{{ */
{
zend_ssa_var *ssa_vars;
int i;
if (!ssa->vars) {
ssa->vars = zend_arena_calloc(arena, ssa->vars_count, sizeof(zend_ssa_var));
}
ssa_vars = ssa->vars;
for (i = 0; i < op_array->last_var; i++) {
ssa_vars[i].var = i;
ssa_vars[i].scc = -1;
ssa_vars[i].definition = -1;
ssa_vars[i].use_chain = -1;
}
for (i = op_array->last_var; i < ssa->vars_count; i++) {
ssa_vars[i].var = -1;
ssa_vars[i].scc = -1;
ssa_vars[i].definition = -1;
ssa_vars[i].use_chain = -1;
}
for (i = op_array->last - 1; i >= 0; i--) {
zend_ssa_op *op = ssa->ops + i;
if (op->op1_use >= 0) {
op->op1_use_chain = ssa_vars[op->op1_use].use_chain;
ssa_vars[op->op1_use].use_chain = i;
}
if (op->op2_use >= 0 && op->op2_use != op->op1_use) {
op->op2_use_chain = ssa_vars[op->op2_use].use_chain;
ssa_vars[op->op2_use].use_chain = i;
}
if (op->result_use >= 0 && op->result_use != op->op1_use && op->result_use != op->op2_use) {
op->res_use_chain = ssa_vars[op->result_use].use_chain;
ssa_vars[op->result_use].use_chain = i;
}
if (op->op1_def >= 0) {
ssa_vars[op->op1_def].var = EX_VAR_TO_NUM(op_array->opcodes[i].op1.var);
ssa_vars[op->op1_def].definition = i;
}
if (op->op2_def >= 0) {
ssa_vars[op->op2_def].var = EX_VAR_TO_NUM(op_array->opcodes[i].op2.var);
ssa_vars[op->op2_def].definition = i;
}
if (op->result_def >= 0) {
ssa_vars[op->result_def].var = EX_VAR_TO_NUM(op_array->opcodes[i].result.var);
ssa_vars[op->result_def].definition = i;
}
}
for (i = 0; i < ssa->cfg.blocks_count; i++) {
zend_ssa_phi *phi = ssa->blocks[i].phis;
while (phi) {
phi->block = i;
ssa_vars[phi->ssa_var].var = phi->var;
ssa_vars[phi->ssa_var].definition_phi = phi;
if (phi->pi >= 0) {
zend_ssa_phi *p;
ZEND_ASSERT(phi->sources[0] >= 0);
p = ssa_vars[phi->sources[0]].phi_use_chain;
while (p && p != phi) {
p = zend_ssa_next_use_phi(ssa, phi->sources[0], p);
}
if (!p) {
phi->use_chains[0] = ssa_vars[phi->sources[0]].phi_use_chain;
ssa_vars[phi->sources[0]].phi_use_chain = phi;
}
if (phi->has_range_constraint) {
/* min and max variables can't be used together */
zend_ssa_range_constraint *constraint = &phi->constraint.range;
if (constraint->min_ssa_var >= 0) {
phi->sym_use_chain = ssa_vars[constraint->min_ssa_var].sym_use_chain;
ssa_vars[constraint->min_ssa_var].sym_use_chain = phi;
} else if (constraint->max_ssa_var >= 0) {
phi->sym_use_chain = ssa_vars[constraint->max_ssa_var].sym_use_chain;
ssa_vars[constraint->max_ssa_var].sym_use_chain = phi;
}
}
} else {
int j;
for (j = 0; j < ssa->cfg.blocks[i].predecessors_count; j++) {
zend_ssa_phi *p;
ZEND_ASSERT(phi->sources[j] >= 0);
p = ssa_vars[phi->sources[j]].phi_use_chain;
while (p && p != phi) {
p = zend_ssa_next_use_phi(ssa, phi->sources[j], p);
}
if (!p) {
phi->use_chains[j] = ssa_vars[phi->sources[j]].phi_use_chain;
ssa_vars[phi->sources[j]].phi_use_chain = phi;
}
}
}
phi = phi->next;
}
}
/* Mark indirectly accessed variables */
for (i = 0; i < op_array->last_var; i++) {
if ((ssa->cfg.flags & ZEND_FUNC_INDIRECT_VAR_ACCESS)) {
ssa_vars[i].alias = SYMTABLE_ALIAS;
} else if (zend_string_equals_literal(op_array->vars[i], "http_response_header")) {
ssa_vars[i].alias = HTTP_RESPONSE_HEADER_ALIAS;
}
}
for (i = op_array->last_var; i < ssa->vars_count; i++) {
if (ssa_vars[i].var < op_array->last_var) {
ssa_vars[i].alias = ssa_vars[ssa_vars[i].var].alias;
}
}
}
/* }}} */
void zend_ssa_unlink_use_chain(zend_ssa *ssa, int op, int var) /* {{{ */
{
if (ssa->vars[var].use_chain == op) {
ssa->vars[var].use_chain = zend_ssa_next_use(ssa->ops, var, op);
return;
}
int use = ssa->vars[var].use_chain;
while (use >= 0) {
if (ssa->ops[use].result_use == var) {
if (ssa->ops[use].res_use_chain == op) {
ssa->ops[use].res_use_chain = zend_ssa_next_use(ssa->ops, var, op);
return;
} else {
use = ssa->ops[use].res_use_chain;
}
} else if (ssa->ops[use].op1_use == var) {
if (ssa->ops[use].op1_use_chain == op) {
ssa->ops[use].op1_use_chain = zend_ssa_next_use(ssa->ops, var, op);
return;
} else {
use = ssa->ops[use].op1_use_chain;
}
} else if (ssa->ops[use].op2_use == var) {
if (ssa->ops[use].op2_use_chain == op) {
ssa->ops[use].op2_use_chain = zend_ssa_next_use(ssa->ops, var, op);
return;
} else {
use = ssa->ops[use].op2_use_chain;
}
} else {
break;
}
}
/* something wrong */
ZEND_UNREACHABLE();
}
/* }}} */
void zend_ssa_replace_use_chain(zend_ssa *ssa, int op, int new_op, int var) /* {{{ */
{
if (ssa->vars[var].use_chain == op) {
ssa->vars[var].use_chain = new_op;
return;
} else {
int use = ssa->vars[var].use_chain;
while (use >= 0) {
if (ssa->ops[use].result_use == var) {
if (ssa->ops[use].res_use_chain == op) {
ssa->ops[use].res_use_chain = new_op;
return;
} else {
use = ssa->ops[use].res_use_chain;
}
} else if (ssa->ops[use].op1_use == var) {
if (ssa->ops[use].op1_use_chain == op) {
ssa->ops[use].op1_use_chain = new_op;
return;
} else {
use = ssa->ops[use].op1_use_chain;
}
} else if (ssa->ops[use].op2_use == var) {
if (ssa->ops[use].op2_use_chain == op) {
ssa->ops[use].op2_use_chain = new_op;
return;
} else {
use = ssa->ops[use].op2_use_chain;
}
} else {
break;
}
}
}
/* something wrong */
ZEND_UNREACHABLE();
}
/* }}} */
void zend_ssa_remove_instr(zend_ssa *ssa, zend_op *opline, zend_ssa_op *ssa_op) /* {{{ */
{
if (ssa_op->result_use >= 0) {
zend_ssa_unlink_use_chain(ssa, ssa_op - ssa->ops, ssa_op->result_use);
ssa_op->result_use = -1;
ssa_op->res_use_chain = -1;
}
if (ssa_op->op1_use >= 0) {
if (ssa_op->op1_use != ssa_op->op2_use) {
zend_ssa_unlink_use_chain(ssa, ssa_op - ssa->ops, ssa_op->op1_use);
} else {
ssa_op->op2_use_chain = ssa_op->op1_use_chain;
}
ssa_op->op1_use = -1;
ssa_op->op1_use_chain = -1;
}
if (ssa_op->op2_use >= 0) {
zend_ssa_unlink_use_chain(ssa, ssa_op - ssa->ops, ssa_op->op2_use);
ssa_op->op2_use = -1;
ssa_op->op2_use_chain = -1;
}
/* We let the caller make sure that all defs are gone */
ZEND_ASSERT(ssa_op->result_def == -1);
ZEND_ASSERT(ssa_op->op1_def == -1);
ZEND_ASSERT(ssa_op->op2_def == -1);
MAKE_NOP(opline);
}
/* }}} */
static inline zend_ssa_phi **zend_ssa_next_use_phi_ptr(zend_ssa *ssa, int var, 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];
}
}
}
ZEND_UNREACHABLE();
return NULL;
}
/* }}} */
/* May be called even if source is not used in the phi (useful when removing uses in a phi
* with multiple identical operands) */
static inline void zend_ssa_remove_use_of_phi_source(zend_ssa *ssa, zend_ssa_phi *phi, int source, zend_ssa_phi *next_use_phi) /* {{{ */
{
zend_ssa_phi **cur = &ssa->vars[source].phi_use_chain;
while (*cur && *cur != phi) {
cur = zend_ssa_next_use_phi_ptr(ssa, source, *cur);
}
if (*cur) {
*cur = next_use_phi;
}
}
/* }}} */
static void zend_ssa_remove_uses_of_phi_sources(zend_ssa *ssa, zend_ssa_phi *phi) /* {{{ */
{
int source;
FOREACH_PHI_SOURCE(phi, source) {
zend_ssa_remove_use_of_phi_source(ssa, phi, source, zend_ssa_next_use_phi(ssa, source, phi));
} FOREACH_PHI_SOURCE_END();
}
/* }}} */
static void zend_ssa_remove_phi_from_block(zend_ssa *ssa, zend_ssa_phi *phi) /* {{{ */
{
zend_ssa_block *block = &ssa->blocks[phi->block];
zend_ssa_phi **cur = &block->phis;
while (*cur != phi) {
ZEND_ASSERT(*cur != NULL);
cur = &(*cur)->next;
}
*cur = (*cur)->next;
}
/* }}} */
void zend_ssa_remove_defs_of_instr(zend_ssa *ssa, zend_ssa_op *ssa_op) /* {{{ */
{
if (ssa_op->op1_def >= 0) {
zend_ssa_remove_uses_of_var(ssa, ssa_op->op1_def);
zend_ssa_remove_op1_def(ssa, ssa_op);
}
if (ssa_op->op2_def >= 0) {
zend_ssa_remove_uses_of_var(ssa, ssa_op->op2_def);
zend_ssa_remove_op2_def(ssa, ssa_op);
}
if (ssa_op->result_def >= 0) {
zend_ssa_remove_uses_of_var(ssa, ssa_op->result_def);
zend_ssa_remove_result_def(ssa, ssa_op);
}
}
/* }}} */
static inline void zend_ssa_remove_phi_source(zend_ssa *ssa, zend_ssa_phi *phi, int pred_offset, int predecessors_count) /* {{{ */
{
int j, var_num = phi->sources[pred_offset];
zend_ssa_phi *next_phi = phi->use_chains[pred_offset];
predecessors_count--;
if (pred_offset < predecessors_count) {
memmove(phi->sources + pred_offset, phi->sources + pred_offset + 1, (predecessors_count - pred_offset) * sizeof(uint32_t));
memmove(phi->use_chains + pred_offset, phi->use_chains + pred_offset + 1, (predecessors_count - pred_offset) * sizeof(zend_ssa_phi*));
}
/* Check if they same var is used in a different phi operand as well, in this case we don't
* need to adjust the use chain (but may have to move the next pointer). */
for (j = 0; j < predecessors_count; j++) {
if (phi->sources[j] == var_num) {
if (j < pred_offset) {
ZEND_ASSERT(next_phi == NULL);
} else if (j >= pred_offset) {
phi->use_chains[j] = next_phi;
}
return;
}
}
/* Variable only used in one operand, remove the phi from the use chain. */
zend_ssa_remove_use_of_phi_source(ssa, phi, var_num, next_phi);
}
/* }}} */
void zend_ssa_remove_phi(zend_ssa *ssa, zend_ssa_phi *phi) /* {{{ */
{
ZEND_ASSERT(phi->ssa_var >= 0);
ZEND_ASSERT(ssa->vars[phi->ssa_var].use_chain < 0
&& ssa->vars[phi->ssa_var].phi_use_chain == NULL);
zend_ssa_remove_uses_of_phi_sources(ssa, phi);
zend_ssa_remove_phi_from_block(ssa, phi);
ssa->vars[phi->ssa_var].definition_phi = NULL;
phi->ssa_var = -1;
}
/* }}} */
void zend_ssa_remove_uses_of_var(zend_ssa *ssa, int var_num) /* {{{ */
{
zend_ssa_var *var = &ssa->vars[var_num];
zend_ssa_phi *phi;
int use;
FOREACH_PHI_USE(var, phi) {
int i, end = NUM_PHI_SOURCES(phi);
for (i = 0; i < end; i++) {
if (phi->sources[i] == var_num) {
phi->use_chains[i] = NULL;
}
}
} FOREACH_PHI_USE_END();
var->phi_use_chain = NULL;
FOREACH_USE(var, use) {
zend_ssa_op *ssa_op = &ssa->ops[use];
if (ssa_op->op1_use == var_num) {
ssa_op->op1_use = -1;
ssa_op->op1_use_chain = -1;
}
if (ssa_op->op2_use == var_num) {
ssa_op->op2_use = -1;
ssa_op->op2_use_chain = -1;
}
if (ssa_op->result_use == var_num) {
ssa_op->result_use = -1;
ssa_op->res_use_chain = -1;
}
} FOREACH_USE_END();
var->use_chain = -1;
}
/* }}} */
void zend_ssa_remove_predecessor(zend_ssa *ssa, int from, int to) /* {{{ */
{
zend_basic_block *next_block = &ssa->cfg.blocks[to];
zend_ssa_block *next_ssa_block = &ssa->blocks[to];
zend_ssa_phi *phi;
int j;
/* Find at which predecessor offset this block is referenced */
int pred_offset = -1;
int *predecessors = &ssa->cfg.predecessors[next_block->predecessor_offset];
for (j = 0; j < next_block->predecessors_count; j++) {
if (predecessors[j] == from) {
pred_offset = j;
break;
}
}
/* If there are duplicate successors, the predecessors may have been removed in
* a previous iteration already. */
if (pred_offset == -1) {
return;
}
/* For phis in successor blocks, remove the operands associated with this block */
for (phi = next_ssa_block->phis; phi; phi = phi->next) {
if (phi->pi >= 0) {
if (phi->pi == from) {
zend_ssa_rename_var_uses(ssa, phi->ssa_var, phi->sources[0], /* update_types */ 0);
zend_ssa_remove_phi(ssa, phi);
}
} else {
ZEND_ASSERT(phi->sources[pred_offset] >= 0);
zend_ssa_remove_phi_source(ssa, phi, pred_offset, next_block->predecessors_count);
}
}
/* Remove this predecessor */
next_block->predecessors_count--;
if (pred_offset < next_block->predecessors_count) {
predecessors = &ssa->cfg.predecessors[next_block->predecessor_offset + pred_offset];
memmove(predecessors, predecessors + 1, (next_block->predecessors_count - pred_offset) * sizeof(uint32_t));
}
}
/* }}} */
void zend_ssa_remove_block(zend_op_array *op_array, zend_ssa *ssa, int i) /* {{{ */
{
zend_basic_block *block = &ssa->cfg.blocks[i];
zend_ssa_block *ssa_block = &ssa->blocks[i];
zend_ssa_phi *phi;
int j;
block->flags &= ~ZEND_BB_REACHABLE;
/* Removes phis in this block */
for (phi = ssa_block->phis; phi; phi = phi->next) {
zend_ssa_remove_uses_of_var(ssa, phi->ssa_var);
zend_ssa_remove_phi(ssa, phi);
}
/* Remove instructions in this block */
for (j = block->start; j < block->start + block->len; j++) {
if (op_array->opcodes[j].opcode == ZEND_NOP) {
continue;
}
zend_ssa_remove_defs_of_instr(ssa, &ssa->ops[j]);
zend_ssa_remove_instr(ssa, &op_array->opcodes[j], &ssa->ops[j]);
}
zend_ssa_remove_block_from_cfg(ssa, i);
}
/* }}} */
void zend_ssa_remove_block_from_cfg(zend_ssa *ssa, int i) /* {{{ */
{
zend_basic_block *block = &ssa->cfg.blocks[i];
int *predecessors;
int j, s;
for (s = 0; s < block->successors_count; s++) {
zend_ssa_remove_predecessor(ssa, i, block->successors[s]);
}
/* Remove successors of predecessors */
predecessors = &ssa->cfg.predecessors[block->predecessor_offset];
for (j = 0; j < block->predecessors_count; j++) {
if (predecessors[j] >= 0) {
zend_basic_block *prev_block = &ssa->cfg.blocks[predecessors[j]];
for (s = 0; s < prev_block->successors_count; s++) {
if (prev_block->successors[s] == i) {
memmove(prev_block->successors + s,
prev_block->successors + s + 1,
sizeof(int) * (prev_block->successors_count - s - 1));
prev_block->successors_count--;
s--;
}
}
}
}
block->successors_count = 0;
block->predecessors_count = 0;
/* Remove from dominators tree */
if (block->idom >= 0) {
j = ssa->cfg.blocks[block->idom].children;
if (j == i) {
ssa->cfg.blocks[block->idom].children = block->next_child;
} else if (j >= 0) {
while (ssa->cfg.blocks[j].next_child >= 0) {
if (ssa->cfg.blocks[j].next_child == i) {
ssa->cfg.blocks[j].next_child = block->next_child;
break;
}
j = ssa->cfg.blocks[j].next_child;
}
}
}
block->idom = -1;
block->level = -1;
block->children = -1;
block->next_child = -1;
}
/* }}} */
static void propagate_phi_type_widening(zend_ssa *ssa, int var) /* {{{ */
{
zend_ssa_phi *phi;
FOREACH_PHI_USE(&ssa->vars[var], phi) {
if (ssa->var_info[var].type & ~ssa->var_info[phi->ssa_var].type) {
ssa->var_info[phi->ssa_var].type |= ssa->var_info[var].type;
propagate_phi_type_widening(ssa, phi->ssa_var);
}
} FOREACH_PHI_USE_END();
}
/* }}} */
void zend_ssa_rename_var_uses(zend_ssa *ssa, int old, int new, bool update_types) /* {{{ */
{
zend_ssa_var *old_var = &ssa->vars[old];
zend_ssa_var *new_var = &ssa->vars[new];
int use;
zend_ssa_phi *phi;
ZEND_ASSERT(old >= 0 && new >= 0);
ZEND_ASSERT(old != new);
/* Only a no_val is both variables are */
new_var->no_val &= old_var->no_val;
/* Update ssa_op use chains */
FOREACH_USE(old_var, use) {
zend_ssa_op *ssa_op = &ssa->ops[use];
/* If the op already uses the new var, don't add the op to the use
* list again. Instead move the use_chain to the correct operand. */
bool add_to_use_chain = 1;
if (ssa_op->result_use == new) {
add_to_use_chain = 0;
} else if (ssa_op->op1_use == new) {
if (ssa_op->result_use == old) {
ssa_op->res_use_chain = ssa_op->op1_use_chain;
ssa_op->op1_use_chain = -1;
}
add_to_use_chain = 0;
} else if (ssa_op->op2_use == new) {
if (ssa_op->result_use == old) {
ssa_op->res_use_chain = ssa_op->op2_use_chain;
ssa_op->op2_use_chain = -1;
} else if (ssa_op->op1_use == old) {
ssa_op->op1_use_chain = ssa_op->op2_use_chain;
ssa_op->op2_use_chain = -1;
}
add_to_use_chain = 0;
}
/* Perform the actual renaming */
if (ssa_op->result_use == old) {
ssa_op->result_use = new;
}
if (ssa_op->op1_use == old) {
ssa_op->op1_use = new;
}
if (ssa_op->op2_use == old) {
ssa_op->op2_use = new;
}
/* Add op to use chain of new var (if it isn't already). We use the
* first use chain of (result, op1, op2) that has the new variable. */
if (add_to_use_chain) {
if (ssa_op->result_use == new) {
ssa_op->res_use_chain = new_var->use_chain;
new_var->use_chain = use;
} else if (ssa_op->op1_use == new) {
ssa_op->op1_use_chain = new_var->use_chain;
new_var->use_chain = use;
} else {
ZEND_ASSERT(ssa_op->op2_use == new);
ssa_op->op2_use_chain = new_var->use_chain;
new_var->use_chain = use;
}
}
} FOREACH_USE_END();
old_var->use_chain = -1;
/* Update phi use chains */
FOREACH_PHI_USE(old_var, phi) {
int j;
bool after_first_new_source = 0;
/* If the phi already uses the new var, find its use chain, as we may
* need to move it to a different source operand. */
zend_ssa_phi **existing_use_chain_ptr = NULL;
for (j = 0; j < ssa->cfg.blocks[phi->block].predecessors_count; j++) {
if (phi->sources[j] == new) {
existing_use_chain_ptr = &phi->use_chains[j];
break;
}
}
for (j = 0; j < ssa->cfg.blocks[phi->block].predecessors_count; j++) {
if (phi->sources[j] == new) {
after_first_new_source = 1;
} else if (phi->sources[j] == old) {
phi->sources[j] = new;
/* Either move existing use chain to this source, or add the phi
* to the phi use chain of the new variables. Do this only once. */
if (!after_first_new_source) {
if (existing_use_chain_ptr) {
phi->use_chains[j] = *existing_use_chain_ptr;
*existing_use_chain_ptr = NULL;
} else {
phi->use_chains[j] = new_var->phi_use_chain;
new_var->phi_use_chain = phi;
}
after_first_new_source = 1;
} else {
phi->use_chains[j] = NULL;
}
}
}
/* Make sure phi result types are not incorrectly narrow after renaming.
* This should not normally happen, but can occur if we DCE an assignment
* or unset and there is an improper phi-indirected use lateron. */
// TODO Alternatively we could rerun type-inference after DCE
if (update_types && (ssa->var_info[new].type & ~ssa->var_info[phi->ssa_var].type)) {
ssa->var_info[phi->ssa_var].type |= ssa->var_info[new].type;
propagate_phi_type_widening(ssa, phi->ssa_var);
}
} FOREACH_PHI_USE_END();
old_var->phi_use_chain = NULL;
}
/* }}} */
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