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zend_inference.c
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/*
+----------------------------------------------------------------------+
| Zend Engine, e-SSA based Type & Range Inference |
+----------------------------------------------------------------------+
| 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 |
| [email protected] so we can mail you a copy immediately. |
+----------------------------------------------------------------------+
| Authors: Dmitry Stogov <[email protected]> |
+----------------------------------------------------------------------+
*/
#include "zend_compile.h"
#include "zend_generators.h"
#include "zend_inference.h"
#include "zend_func_info.h"
#include "zend_call_graph.h"
#include "zend_closures.h"
#include "zend_worklist.h"
#include "zend_optimizer_internal.h"
/* The used range inference algorithm is described in:
* V. Campos, R. Rodrigues, I. de Assis Costa and F. Pereira.
* "Speed and Precision in Range Analysis", SBLP'12.
*
* There are a couple degrees of freedom, we use:
* * Propagation on SCCs.
* * e-SSA for live range splitting.
* * Only intra-procedural inference.
* * Widening with warmup passes, but without jump sets.
*/
/* Whether to handle symbolic range constraints */
#define SYM_RANGE
/* Whether to handle negative range constraints */
/* Negative range inference is buggy, so disabled for now */
#undef NEG_RANGE
/* Number of warmup passes to use prior to widening */
#define RANGE_WARMUP_PASSES 16
/* Logging for range inference in general */
#if 0
#define LOG_SSA_RANGE(...) fprintf(stderr, __VA_ARGS__)
#else
#define LOG_SSA_RANGE(...)
#endif
/* Logging for negative range constraints */
#if 0
#define LOG_NEG_RANGE(...) fprintf(stderr, __VA_ARGS__)
#else
#define LOG_NEG_RANGE(...)
#endif
/* Pop elements in unspecified order from worklist until it is empty */
#define WHILE_WORKLIST(worklist, len, i) do { \
bool _done = 0; \
while (!_done) { \
_done = 1; \
ZEND_BITSET_FOREACH(worklist, len, i) { \
zend_bitset_excl(worklist, i); \
_done = 0;
#define WHILE_WORKLIST_END() \
} ZEND_BITSET_FOREACH_END(); \
} \
} while (0)
#ifdef SYM_RANGE
# define STORE_CURRENT_SYM recursion_stack[recursion_stack_idx].current_sym = sym_p
#else
# define STORE_CURRENT_SYM
#endif
#define CHECK_SCC_VAR(var2) \
do { \
if (!ssa->vars[var2].no_val) { \
if (dfs[var2] < 0) { \
/* Need to come back from "recursion" */ \
recursion_stack[recursion_stack_idx].var = var; \
recursion_stack[recursion_stack_idx].current_use = use; \
recursion_stack[recursion_stack_idx].current_phi = p; \
STORE_CURRENT_SYM; \
recursion_stack_idx++; \
/* "Recurse" on next var */ \
var = var2; \
use = ssa->vars[var].use_chain; \
p = ssa->vars[var].phi_use_chain; \
sym_p = ssa->vars[var].sym_use_chain; \
dfs[var] = *index; \
(*index)++; \
root[var] = var; \
goto recurse; \
} \
/* Because the use, p, sym_p variables will remain the same from the last iteration,
* this will correctly execute after coming back from the "recursion". */ \
if (ssa->vars[var2].scc < 0 && dfs[root[var]] >= dfs[root[var2]]) { \
root[var] = root[var2]; \
} \
} \
} while (0)
#define CHECK_SCC_ENTRY(var2) \
do { \
if (ssa->vars[var2].scc != ssa->vars[var].scc) { \
ssa->vars[var2].scc_entry = 1; \
} \
} while (0)
#define ADD_SCC_VAR(_var) \
do { \
if (ssa->vars[_var].scc == scc && \
!(ssa->var_info[_var].type & MAY_BE_REF)) { \
zend_bitset_incl(worklist, _var); \
} \
} while (0)
#define ADD_SCC_VAR_1(_var) \
do { \
if (ssa->vars[_var].scc == scc && \
!(ssa->var_info[_var].type & MAY_BE_REF) && \
!zend_bitset_in(visited, _var)) { \
zend_bitset_incl(worklist, _var); \
} \
} while (0)
#define FOR_EACH_DEFINED_VAR(line, MACRO) \
do { \
if (ssa->ops[line].op1_def >= 0) { \
MACRO(ssa->ops[line].op1_def); \
} \
if (ssa->ops[line].op2_def >= 0) { \
MACRO(ssa->ops[line].op2_def); \
} \
if (ssa->ops[line].result_def >= 0) { \
MACRO(ssa->ops[line].result_def); \
} \
if (op_array->opcodes[line].opcode == ZEND_OP_DATA) { \
if (ssa->ops[line-1].op1_def >= 0) { \
MACRO(ssa->ops[line-1].op1_def); \
} \
if (ssa->ops[line-1].op2_def >= 0) { \
MACRO(ssa->ops[line-1].op2_def); \
} \
if (ssa->ops[line-1].result_def >= 0) { \
MACRO(ssa->ops[line-1].result_def); \
} \
} else if ((uint32_t)line+1 < op_array->last && \
op_array->opcodes[line+1].opcode == ZEND_OP_DATA) { \
if (ssa->ops[line+1].op1_def >= 0) { \
MACRO(ssa->ops[line+1].op1_def); \
} \
if (ssa->ops[line+1].op2_def >= 0) { \
MACRO(ssa->ops[line+1].op2_def); \
} \
if (ssa->ops[line+1].result_def >= 0) { \
MACRO(ssa->ops[line+1].result_def); \
} \
} \
} while (0)
#define FOR_EACH_VAR_USAGE_EX(_var, MACRO) \
do { \
while (use >= 0) { \
FOR_EACH_DEFINED_VAR(use, MACRO); \
use = zend_ssa_next_use(ssa->ops, _var, use); \
} \
while (p) { \
MACRO(p->ssa_var); \
p = zend_ssa_next_use_phi(ssa, _var, p); \
} \
} while (0)
#define FOR_EACH_VAR_USAGE(_var, MACRO) \
do { \
int use = ssa->vars[_var].use_chain; \
zend_ssa_phi *p = ssa->vars[_var].phi_use_chain; \
FOR_EACH_VAR_USAGE_EX(_var, MACRO); \
} while (0)
static inline bool add_will_overflow(zend_long a, zend_long b) {
return (b > 0 && a > ZEND_LONG_MAX - b)
|| (b < 0 && a < ZEND_LONG_MIN - b);
}
#if 0
static inline bool sub_will_overflow(zend_long a, zend_long b) {
return (b > 0 && a < ZEND_LONG_MIN + b)
|| (b < 0 && a > ZEND_LONG_MAX + b);
}
#endif
typedef struct {
int var;
int current_use;
const zend_ssa_phi *current_phi;
#ifdef SYM_RANGE
const zend_ssa_phi *current_sym;
#endif
} scc_recursion_entry;
static void zend_ssa_check_scc_var(const zend_op_array *op_array, zend_ssa *ssa, int var, int *index, int *dfs, int *root, zend_worklist_stack *stack) /* {{{ */
{
ALLOCA_FLAG(recursion_stack_use_heap);
/* Manual recursion stack that tracks to which variable the recursion should "return" to.
* The number of elements cannot be greater than the variable count because every time a variable is visited it is marked and won't be visited again.
* Each recursion consists of three/four stack elements: (variable, current use chain iterator, current phi node iterator, optionally current sym use chain iterator). */
scc_recursion_entry *recursion_stack = do_alloca(sizeof(scc_recursion_entry) * ssa->vars_count, recursion_stack_use_heap);
uint32_t recursion_stack_idx = 1;
dfs[var] = *index;
(*index)++;
root[var] = var;
recursion_stack[0].var = var;
recursion_stack[0].current_use = ssa->vars[var].use_chain;
recursion_stack[0].current_phi = ssa->vars[var].phi_use_chain;
#ifdef SYM_RANGE
recursion_stack[0].current_sym = ssa->vars[var].sym_use_chain;
#endif
do {
recursion_stack_idx--;
var = recursion_stack[recursion_stack_idx].var;
int use = recursion_stack[recursion_stack_idx].current_use;
const zend_ssa_phi *p = recursion_stack[recursion_stack_idx].current_phi;
#ifdef SYM_RANGE
const zend_ssa_phi *sym_p = recursion_stack[recursion_stack_idx].current_sym;
#endif
recurse:;
FOR_EACH_VAR_USAGE_EX(var, CHECK_SCC_VAR);
#ifdef SYM_RANGE
/* Process symbolic control-flow constraints */
while (sym_p) {
CHECK_SCC_VAR(sym_p->ssa_var);
sym_p = sym_p->sym_use_chain;
}
#endif
if (root[var] == var) {
ssa->vars[var].scc = ssa->sccs;
while (stack->len > 0) {
int var2 = zend_worklist_stack_peek(stack);
if (dfs[var2] <= dfs[var]) {
break;
}
zend_worklist_stack_pop(stack);
ssa->vars[var2].scc = ssa->sccs;
}
ssa->sccs++;
} else {
zend_worklist_stack_push(stack, var);
}
} while (recursion_stack_idx > 0);
free_alloca(recursion_stack, recursion_stack_use_heap);
}
/* }}} */
ZEND_API int zend_ssa_find_sccs(const zend_op_array *op_array, zend_ssa *ssa) /* {{{ */
{
int index = 0, *dfs, *root;
zend_worklist_stack stack;
int j;
ALLOCA_FLAG(dfs_use_heap)
ALLOCA_FLAG(root_use_heap)
ALLOCA_FLAG(stack_use_heap)
dfs = do_alloca(sizeof(int) * ssa->vars_count, dfs_use_heap);
memset(dfs, -1, sizeof(int) * ssa->vars_count);
root = do_alloca(sizeof(int) * ssa->vars_count, root_use_heap);
ZEND_WORKLIST_STACK_ALLOCA(&stack, ssa->vars_count, stack_use_heap);
/* Find SCCs using Tarjan's algorithm. */
for (j = 0; j < ssa->vars_count; j++) {
if (!ssa->vars[j].no_val && dfs[j] < 0) {
zend_ssa_check_scc_var(op_array, ssa, j, &index, dfs, root, &stack);
}
}
/* Revert SCC order. This results in a topological order. */
for (j = 0; j < ssa->vars_count; j++) {
if (ssa->vars[j].scc >= 0) {
ssa->vars[j].scc = ssa->sccs - (ssa->vars[j].scc + 1);
}
}
for (j = 0; j < ssa->vars_count; j++) {
if (ssa->vars[j].scc >= 0) {
int var = j;
if (root[j] == j) {
ssa->vars[j].scc_entry = 1;
}
FOR_EACH_VAR_USAGE(var, CHECK_SCC_ENTRY);
}
}
ZEND_WORKLIST_STACK_FREE_ALLOCA(&stack, stack_use_heap);
free_alloca(root, root_use_heap);
free_alloca(dfs, dfs_use_heap);
return SUCCESS;
}
/* }}} */
ZEND_API int zend_ssa_find_false_dependencies(const zend_op_array *op_array, zend_ssa *ssa) /* {{{ */
{
zend_ssa_var *ssa_vars = ssa->vars;
zend_ssa_op *ssa_ops = ssa->ops;
int ssa_vars_count = ssa->vars_count;
zend_bitset worklist;
int i, j, use;
zend_ssa_phi *p;
ALLOCA_FLAG(use_heap);
if (!op_array->function_name || !ssa->vars || !ssa->ops) {
return SUCCESS;
}
worklist = do_alloca(sizeof(zend_ulong) * zend_bitset_len(ssa_vars_count), use_heap);
memset(worklist, 0, sizeof(zend_ulong) * zend_bitset_len(ssa_vars_count));
for (i = 0; i < ssa_vars_count; i++) {
ssa_vars[i].no_val = 1; /* mark as unused */
use = ssa->vars[i].use_chain;
while (use >= 0) {
if (!zend_ssa_is_no_val_use(&op_array->opcodes[use], &ssa->ops[use], i)) {
ssa_vars[i].no_val = 0; /* used directly */
zend_bitset_incl(worklist, i);
break;
}
use = zend_ssa_next_use(ssa_ops, i, use);
}
}
WHILE_WORKLIST(worklist, zend_bitset_len(ssa_vars_count), i) {
if (ssa_vars[i].definition_phi) {
/* mark all possible sources as used */
p = ssa_vars[i].definition_phi;
if (p->pi >= 0) {
if (ssa_vars[p->sources[0]].no_val) {
ssa_vars[p->sources[0]].no_val = 0; /* used indirectly */
zend_bitset_incl(worklist, p->sources[0]);
}
} else {
for (j = 0; j < ssa->cfg.blocks[p->block].predecessors_count; j++) {
ZEND_ASSERT(p->sources[j] >= 0);
if (ssa->vars[p->sources[j]].no_val) {
ssa_vars[p->sources[j]].no_val = 0; /* used indirectly */
zend_bitset_incl(worklist, p->sources[j]);
}
}
}
}
} WHILE_WORKLIST_END();
free_alloca(worklist, use_heap);
return SUCCESS;
}
/* }}} */
/* From "Hacker's Delight" */
zend_ulong minOR(zend_ulong a, zend_ulong b, zend_ulong c, zend_ulong d)
{
zend_ulong m, temp;
m = Z_UL(1) << (sizeof(zend_ulong) * 8 - 1);
while (m != 0) {
if (~a & c & m) {
temp = (a | m) & -m;
if (temp <= b) {
a = temp;
break;
}
} else if (a & ~c & m) {
temp = (c | m) & -m;
if (temp <= d) {
c = temp;
break;
}
}
m = m >> 1;
}
return a | c;
}
zend_ulong maxOR(zend_ulong a, zend_ulong b, zend_ulong c, zend_ulong d)
{
zend_ulong m, temp;
m = Z_UL(1) << (sizeof(zend_ulong) * 8 - 1);
while (m != 0) {
if (b & d & m) {
temp = (b - m) | (m - 1);
if (temp >= a) {
b = temp;
break;
}
temp = (d - m) | (m - 1);
if (temp >= c) {
d = temp;
break;
}
}
m = m >> 1;
}
return b | d;
}
zend_ulong minAND(zend_ulong a, zend_ulong b, zend_ulong c, zend_ulong d)
{
zend_ulong m, temp;
m = Z_UL(1) << (sizeof(zend_ulong) * 8 - 1);
while (m != 0) {
if (~a & ~c & m) {
temp = (a | m) & -m;
if (temp <= b) {
a = temp;
break;
}
temp = (c | m) & -m;
if (temp <= d) {
c = temp;
break;
}
}
m = m >> 1;
}
return a & c;
}
zend_ulong maxAND(zend_ulong a, zend_ulong b, zend_ulong c, zend_ulong d)
{
zend_ulong m, temp;
m = Z_UL(1) << (sizeof(zend_ulong) * 8 - 1);
while (m != 0) {
if (b & ~d & m) {
temp = (b | ~m) | (m - 1);
if (temp >= a) {
b = temp;
break;
}
} else if (~b & d & m) {
temp = (d | ~m) | (m - 1);
if (temp >= c) {
d = temp;
break;
}
}
m = m >> 1;
}
return b & d;
}
zend_ulong minXOR(zend_ulong a, zend_ulong b, zend_ulong c, zend_ulong d)
{
return minAND(a, b, ~d, ~c) | minAND(~b, ~a, c, d);
}
zend_ulong maxXOR(zend_ulong a, zend_ulong b, zend_ulong c, zend_ulong d)
{
return maxOR(0, maxAND(a, b, ~d, ~c), 0, maxAND(~b, ~a, c, d));
}
/* Based on "Hacker's Delight" */
/*
0: + + + + 0 0 0 0 => 0 0 + min/max
2: + + - + 0 0 1 0 => 1 0 ? min(a,b,c,-1)/max(a,b,0,d)
3: + + - - 0 0 1 1 => 1 1 - min/max
8: - + + + 1 0 0 0 => 1 0 ? min(a,-1,b,d)/max(0,b,c,d)
a: - + - + 1 0 1 0 => 1 0 ? MIN(a,c)/max(0,b,0,d)
b: - + - - 1 0 1 1 => 1 1 - c/-1
c: - - + + 1 1 0 0 => 1 1 - min/max
e: - - - + 1 1 1 0 => 1 1 - a/-1
f - - - - 1 1 1 1 => 1 1 - min/max
*/
static void zend_ssa_range_or(zend_long a, zend_long b, zend_long c, zend_long d, zend_ssa_range *tmp)
{
int x = ((a < 0) ? 8 : 0) |
((b < 0) ? 4 : 0) |
((c < 0) ? 2 : 0) |
((d < 0) ? 1 : 0);
switch (x) {
case 0x0:
case 0x3:
case 0xc:
case 0xf:
tmp->min = minOR(a, b, c, d);
tmp->max = maxOR(a, b, c, d);
break;
case 0x2:
tmp->min = minOR(a, b, c, -1);
tmp->max = maxOR(a, b, 0, d);
break;
case 0x8:
tmp->min = minOR(a, -1, c, d);
tmp->max = maxOR(0, b, c, d);
break;
case 0xa:
tmp->min = MIN(a, c);
tmp->max = maxOR(0, b, 0, d);
break;
case 0xb:
tmp->min = c;
tmp->max = -1;
break;
case 0xe:
tmp->min = a;
tmp->max = -1;
break;
}
}
/*
0: + + + + 0 0 0 0 => 0 0 + min/max
2: + + - + 0 0 1 0 => 0 0 + 0/b
3: + + - - 0 0 1 1 => 0 0 + min/max
8: - + + + 1 0 0 0 => 0 0 + 0/d
a: - + - + 1 0 1 0 => 1 0 ? min(a,-1,c,-1)/NAX(b,d)
b: - + - - 1 0 1 1 => 1 0 ? min(a,-1,c,d)/max(0,b,c,d)
c: - - + + 1 1 0 0 => 1 1 - min/max
e: - - - + 1 1 1 0 => 1 0 ? min(a,b,c,-1)/max(a,b,0,d)
f - - - - 1 1 1 1 => 1 1 - min/max
*/
static void zend_ssa_range_and(zend_long a, zend_long b, zend_long c, zend_long d, zend_ssa_range *tmp)
{
int x = ((a < 0) ? 8 : 0) |
((b < 0) ? 4 : 0) |
((c < 0) ? 2 : 0) |
((d < 0) ? 1 : 0);
switch (x) {
case 0x0:
case 0x3:
case 0xc:
case 0xf:
tmp->min = minAND(a, b, c, d);
tmp->max = maxAND(a, b, c, d);
break;
case 0x2:
tmp->min = 0;
tmp->max = b;
break;
case 0x8:
tmp->min = 0;
tmp->max = d;
break;
case 0xa:
tmp->min = minAND(a, -1, c, -1);
tmp->max = MAX(b, d);
break;
case 0xb:
tmp->min = minAND(a, -1, c, d);
tmp->max = maxAND(0, b, c, d);
break;
case 0xe:
tmp->min = minAND(a, b, c, -1);
tmp->max = maxAND(a, b, 0, d);
break;
}
}
static inline bool zend_abs_range(
zend_long min, zend_long max, zend_long *abs_min, zend_long *abs_max) {
if (min == ZEND_LONG_MIN) {
/* Cannot take absolute value of LONG_MIN */
return 0;
}
if (min >= 0) {
*abs_min = min;
*abs_max = max;
} else if (max <= 0) {
*abs_min = -max;
*abs_max = -min;
} else {
/* Range crossing zero */
*abs_min = 0;
*abs_max = MAX(max, -min);
}
return 1;
}
static inline zend_long safe_shift_left(zend_long n, zend_long s) {
return (zend_long) ((zend_ulong) n << (zend_ulong) s);
}
static inline bool shift_left_overflows(zend_long n, zend_long s) {
/* This considers shifts that shift in the sign bit to be overflowing as well */
if (n >= 0) {
return s >= SIZEOF_ZEND_LONG * 8 - 1 || safe_shift_left(n, s) < n;
} else {
return s >= SIZEOF_ZEND_LONG * 8 || safe_shift_left(n, s) > n;
}
}
/* If b does not divide a exactly, return the two adjacent values between which the real result
* lies. */
static void float_div(zend_long a, zend_long b, zend_long *r1, zend_long *r2) {
*r1 = *r2 = a / b;
if (a % b != 0) {
if (*r2 < 0) {
(*r2)--;
} else {
(*r2)++;
}
}
}
static int zend_inference_calc_binary_op_range(
const zend_op_array *op_array, zend_ssa *ssa,
zend_op *opline, zend_ssa_op *ssa_op, zend_uchar opcode, zend_ssa_range *tmp) {
zend_long op1_min, op2_min, op1_max, op2_max, t1, t2, t3, t4;
switch (opcode) {
case ZEND_ADD:
if (OP1_HAS_RANGE() && OP2_HAS_RANGE()) {
op1_min = OP1_MIN_RANGE();
op2_min = OP2_MIN_RANGE();
op1_max = OP1_MAX_RANGE();
op2_max = OP2_MAX_RANGE();
if (OP1_RANGE_UNDERFLOW() ||
OP2_RANGE_UNDERFLOW() ||
zend_add_will_overflow(op1_min, op2_min)) {
tmp->underflow = 1;
tmp->min = ZEND_LONG_MIN;
} else {
tmp->min = op1_min + op2_min;
}
if (OP1_RANGE_OVERFLOW() ||
OP2_RANGE_OVERFLOW() ||
zend_add_will_overflow(op1_max, op2_max)) {
tmp->overflow = 1;
tmp->max = ZEND_LONG_MAX;
} else {
tmp->max = op1_max + op2_max;
}
return 1;
}
break;
case ZEND_SUB:
if (OP1_HAS_RANGE() && OP2_HAS_RANGE()) {
op1_min = OP1_MIN_RANGE();
op2_min = OP2_MIN_RANGE();
op1_max = OP1_MAX_RANGE();
op2_max = OP2_MAX_RANGE();
if (OP1_RANGE_UNDERFLOW() ||
OP2_RANGE_OVERFLOW() ||
zend_sub_will_overflow(op1_min, op2_max)) {
tmp->underflow = 1;
tmp->min = ZEND_LONG_MIN;
} else {
tmp->min = op1_min - op2_max;
}
if (OP1_RANGE_OVERFLOW() ||
OP2_RANGE_UNDERFLOW() ||
zend_sub_will_overflow(op1_max, op2_min)) {
tmp->overflow = 1;
tmp->max = ZEND_LONG_MAX;
} else {
tmp->max = op1_max - op2_min;
}
return 1;
}
break;
case ZEND_MUL:
if (OP1_HAS_RANGE() && OP2_HAS_RANGE()) {
double dummy;
zend_long t1_overflow, t2_overflow, t3_overflow, t4_overflow;
op1_min = OP1_MIN_RANGE();
op2_min = OP2_MIN_RANGE();
op1_max = OP1_MAX_RANGE();
op2_max = OP2_MAX_RANGE();
/* Suppress uninit variable warnings, these will only be used if the overflow
* flags are all false. */
t1 = t2 = t3 = t4 = 0;
ZEND_SIGNED_MULTIPLY_LONG(op1_min, op2_min, t1, dummy, t1_overflow);
ZEND_SIGNED_MULTIPLY_LONG(op1_min, op2_max, t2, dummy, t2_overflow);
ZEND_SIGNED_MULTIPLY_LONG(op1_max, op2_min, t3, dummy, t3_overflow);
ZEND_SIGNED_MULTIPLY_LONG(op1_max, op2_max, t4, dummy, t4_overflow);
(void) dummy;
// FIXME: more careful overflow checks?
if (OP1_RANGE_UNDERFLOW() || OP2_RANGE_UNDERFLOW() ||
OP1_RANGE_OVERFLOW() || OP2_RANGE_OVERFLOW() ||
t1_overflow || t2_overflow || t3_overflow || t4_overflow
) {
tmp->underflow = 1;
tmp->overflow = 1;
tmp->min = ZEND_LONG_MIN;
tmp->max = ZEND_LONG_MAX;
} else {
tmp->min = MIN(MIN(t1, t2), MIN(t3, t4));
tmp->max = MAX(MAX(t1, t2), MAX(t3, t4));
}
return 1;
}
break;
case ZEND_DIV:
if (OP1_HAS_RANGE() && OP2_HAS_RANGE()) {
op1_min = OP1_MIN_RANGE();
op2_min = OP2_MIN_RANGE();
op1_max = OP1_MAX_RANGE();
op2_max = OP2_MAX_RANGE();
/* If op2 crosses zero, then floating point values close to zero might be
* possible, which will result in arbitrarily large results (overflow). Also
* avoid dividing LONG_MIN by -1, which is UB. */
if (OP1_RANGE_UNDERFLOW() || OP2_RANGE_UNDERFLOW() ||
OP1_RANGE_OVERFLOW() || OP2_RANGE_OVERFLOW() ||
(op2_min <= 0 && op2_max >= 0) ||
(op1_min == ZEND_LONG_MIN && op2_max == -1)
) {
tmp->underflow = 1;
tmp->overflow = 1;
tmp->min = ZEND_LONG_MIN;
tmp->max = ZEND_LONG_MAX;
} else {
zend_long t1_, t2_, t3_, t4_;
float_div(op1_min, op2_min, &t1, &t1_);
float_div(op1_min, op2_max, &t2, &t2_);
float_div(op1_max, op2_min, &t3, &t3_);
float_div(op1_max, op2_max, &t4, &t4_);
tmp->min = MIN(MIN(MIN(t1, t2), MIN(t3, t4)), MIN(MIN(t1_, t2_), MIN(t3_, t4_)));
tmp->max = MAX(MAX(MAX(t1, t2), MAX(t3, t4)), MAX(MAX(t1_, t2_), MAX(t3_, t4_)));
}
return 1;
}
break;
case ZEND_MOD:
if (OP1_HAS_RANGE() && OP2_HAS_RANGE()) {
if (OP1_RANGE_UNDERFLOW() ||
OP2_RANGE_UNDERFLOW() ||
OP1_RANGE_OVERFLOW() ||
OP2_RANGE_OVERFLOW()) {
tmp->min = ZEND_LONG_MIN;
tmp->max = ZEND_LONG_MAX;
} else {
zend_long op2_abs_min, op2_abs_max;
op1_min = OP1_MIN_RANGE();
op2_min = OP2_MIN_RANGE();
op1_max = OP1_MAX_RANGE();
op2_max = OP2_MAX_RANGE();
if (!zend_abs_range(op2_min, op2_max, &op2_abs_min, &op2_abs_max)) {
break;
}
if (op2_abs_max == 0) {
/* Always modulus by zero, nothing we can do */
break;
}
if (op2_abs_min == 0) {
/* Ignore the modulus by zero case, which will throw */
op2_abs_min++;
}
if (op1_min >= 0) {
tmp->min = op1_max < op2_abs_min ? op1_min : 0;
tmp->max = MIN(op1_max, op2_abs_max - 1);
} else if (op1_max <= 0) {
tmp->min = MAX(op1_min, -op2_abs_max + 1);
tmp->max = op1_min > -op2_abs_min ? op1_max : 0;
} else {
tmp->min = MAX(op1_min, -op2_abs_max + 1);
tmp->max = MIN(op1_max, op2_abs_max - 1);
}
}
return 1;
}
break;
case ZEND_SL:
if (OP1_HAS_RANGE() && OP2_HAS_RANGE()) {
if (OP1_RANGE_UNDERFLOW() ||
OP2_RANGE_UNDERFLOW() ||
OP1_RANGE_OVERFLOW() ||
OP2_RANGE_OVERFLOW()) {
tmp->min = ZEND_LONG_MIN;
tmp->max = ZEND_LONG_MAX;
} else {
op1_min = OP1_MIN_RANGE();
op2_min = OP2_MIN_RANGE();
op1_max = OP1_MAX_RANGE();
op2_max = OP2_MAX_RANGE();
/* Shifts by negative numbers will throw, ignore them */
if (op2_min < 0) {
op2_min = 0;
}
if (op2_max < 0) {
op2_max = 0;
}
if (shift_left_overflows(op1_min, op2_max)
|| shift_left_overflows(op1_max, op2_max)) {
tmp->min = ZEND_LONG_MIN;
tmp->max = ZEND_LONG_MAX;
} else {
t1 = safe_shift_left(op1_min, op2_min);
t2 = safe_shift_left(op1_min, op2_max);
t3 = safe_shift_left(op1_max, op2_min);
t4 = safe_shift_left(op1_max, op2_max);
tmp->min = MIN(MIN(t1, t2), MIN(t3, t4));
tmp->max = MAX(MAX(t1, t2), MAX(t3, t4));
}
}
return 1;
}
break;
case ZEND_SR:
if (OP1_HAS_RANGE() && OP2_HAS_RANGE()) {
if (OP1_RANGE_UNDERFLOW() ||
OP2_RANGE_UNDERFLOW() ||
OP1_RANGE_OVERFLOW() ||
OP2_RANGE_OVERFLOW()) {
tmp->min = ZEND_LONG_MIN;
tmp->max = ZEND_LONG_MAX;
} else {
op1_min = OP1_MIN_RANGE();
op2_min = OP2_MIN_RANGE();
op1_max = OP1_MAX_RANGE();
op2_max = OP2_MAX_RANGE();
/* Shifts by negative numbers will throw, ignore them */
if (op2_min < 0) {
op2_min = 0;
}
if (op2_max < 0) {
op2_max = 0;
}
/* Shifts by more than the integer size will be 0 or -1 */
if (op2_min >= SIZEOF_ZEND_LONG * 8) {
op2_min = SIZEOF_ZEND_LONG * 8 - 1;
}
if (op2_max >= SIZEOF_ZEND_LONG * 8) {
op2_max = SIZEOF_ZEND_LONG * 8 - 1;
}
t1 = op1_min >> op2_min;
t2 = op1_min >> op2_max;
t3 = op1_max >> op2_min;
t4 = op1_max >> op2_max;
tmp->min = MIN(MIN(t1, t2), MIN(t3, t4));
tmp->max = MAX(MAX(t1, t2), MAX(t3, t4));
}
return 1;
}
break;
case ZEND_BW_OR:
if (OP1_HAS_RANGE() && OP2_HAS_RANGE()) {
if (OP1_RANGE_UNDERFLOW() ||
OP2_RANGE_UNDERFLOW() ||
OP1_RANGE_OVERFLOW() ||
OP2_RANGE_OVERFLOW()) {
tmp->min = ZEND_LONG_MIN;
tmp->max = ZEND_LONG_MAX;
} else {
op1_min = OP1_MIN_RANGE();
op2_min = OP2_MIN_RANGE();
op1_max = OP1_MAX_RANGE();
op2_max = OP2_MAX_RANGE();
zend_ssa_range_or(op1_min, op1_max, op2_min, op2_max, tmp);
}
return 1;
}
break;
case ZEND_BW_AND:
if (OP1_HAS_RANGE() && OP2_HAS_RANGE()) {
if (OP1_RANGE_UNDERFLOW() ||
OP2_RANGE_UNDERFLOW() ||
OP1_RANGE_OVERFLOW() ||
OP2_RANGE_OVERFLOW()) {
tmp->min = ZEND_LONG_MIN;
tmp->max = ZEND_LONG_MAX;
} else {
op1_min = OP1_MIN_RANGE();
op2_min = OP2_MIN_RANGE();
op1_max = OP1_MAX_RANGE();
op2_max = OP2_MAX_RANGE();
zend_ssa_range_and(op1_min, op1_max, op2_min, op2_max, tmp);
}
return 1;
}
break;
case ZEND_BW_XOR:
// TODO
break;
EMPTY_SWITCH_DEFAULT_CASE()
}
return 0;
}
static int zend_inference_calc_range(const zend_op_array *op_array, zend_ssa *ssa, int var, int widening, int narrowing, zend_ssa_range *tmp)
{
uint32_t line;
zend_op *opline;
zend_ssa_op *ssa_op;
if (ssa->vars[var].definition_phi) {
zend_ssa_phi *p = ssa->vars[var].definition_phi;
int i;
tmp->underflow = 0;
tmp->min = ZEND_LONG_MAX;
tmp->max = ZEND_LONG_MIN;
tmp->overflow = 0;
if (p->pi >= 0 && p->has_range_constraint) {
zend_ssa_range_constraint *constraint = &p->constraint.range;
if (constraint->negative) {
int src1 = p->sources[0];
if (ssa->var_info[src1].has_range) {
*tmp = ssa->var_info[src1].range;
if (constraint->range.min == constraint->range.max
&& !constraint->range.underflow
&& !constraint->range.overflow
&& p->constraint.range.min_ssa_var < 0
&& p->constraint.range.max_ssa_var < 0
&& ssa->vars[src1].definition >= 0) {
/* Check for constrained induction variable */
line = ssa->vars[src1].definition;
opline = op_array->opcodes + line;
switch (opline->opcode) {
case ZEND_PRE_DEC:
case ZEND_POST_DEC:
if (!tmp->underflow) {
zend_ssa_phi *p = ssa->vars[ssa->ops[line].op1_use].definition_phi;
if (p && p->pi < 0
&& ssa->cfg.blocks[p->block].predecessors_count == 2
&& p->sources[1] == var
&& ssa->var_info[p->sources[0]].has_range
&& ssa->var_info[p->sources[0]].range.min > constraint->range.max) {
tmp->min = constraint->range.max + 1;
}
}
break;
case ZEND_PRE_INC:
case ZEND_POST_INC:
if (!tmp->overflow) {
zend_ssa_phi *p = ssa->vars[ssa->ops[line].op1_use].definition_phi;
if (p && p->pi < 0
&& ssa->cfg.blocks[p->block].predecessors_count == 2
&& p->sources[1] == var
&& ssa->var_info[p->sources[0]].has_range
&& ssa->var_info[p->sources[0]].range.max < constraint->range.min) {
tmp->max = constraint->range.min - 1;
}
}
break;
}
}
} else if (narrowing) {
tmp->underflow = 1;
tmp->min = ZEND_LONG_MIN;
tmp->max = ZEND_LONG_MAX;
tmp->overflow = 1;
}
#ifdef NEG_RANGE
if (constraint->min_ssa_var < 0 &&
constraint->max_ssa_var < 0 &&
ssa->var_info[p->ssa_var].has_range) {
LOG_NEG_RANGE("%s() #%d [%ld..%ld] -> [%ld..%ld]?\n",
ZSTR_VAL(op_array->function_name),
p->ssa_var,
ssa->var_info[p->ssa_var].range.min,
ssa->var_info[p->ssa_var].range.max,
tmp->min,
tmp->max);
if (constraint->negative == NEG_USE_LT &&
tmp->max >= constraint->range.min) {
tmp->overflow = 0;
tmp->max = constraint->range.min - 1;
LOG_NEG_RANGE(" => [%ld..%ld]\n", tmp->min, tmp->max);
} else if (constraint->negative == NEG_USE_GT &&
tmp->min <= constraint->range.max) {
tmp->underflow = 0;
tmp->min = constraint->range.max + 1;
LOG_NEG_RANGE(" => [%ld..%ld]\n", tmp->min, tmp->max);
}
}
#endif
} else if (ssa->var_info[p->sources[0]].has_range) {