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php-src/Zend/Optimizer/pass3.c
Nikita Popov 0015fc9a8e Merge branch 'PHP-8.0' into PHP-8.1 
* PHP-8.0:
  Fix relative offsets when copying JMPZNZ
2021-09-27 16:20:04 +02:00

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/*
+----------------------------------------------------------------------+
| Zend OPcache |
+----------------------------------------------------------------------+
| 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: Andi Gutmans <andi@php.net> |
| Zeev Suraski <zeev@php.net> |
| Stanislav Malyshev <stas@zend.com> |
| Dmitry Stogov <dmitry@php.net> |
+----------------------------------------------------------------------+
*/
/* pass 3: (Jump optimization)
* - optimize series of JMPs
*/
#include "Optimizer/zend_optimizer.h"
#include "Optimizer/zend_optimizer_internal.h"
#include "zend_API.h"
#include "zend_constants.h"
#include "zend_execute.h"
#include "zend_vm.h"
/* we use "jmp_hitlist" to avoid infinity loops during jmp optimization */
static zend_always_inline int in_hitlist(zend_op *target, zend_op **jmp_hitlist, int jmp_hitlist_count)
{
int i;
for (i = 0; i < jmp_hitlist_count; i++) {
if (jmp_hitlist[i] == target) {
return 1;
}
}
return 0;
}
#define CHECK_LOOP(target) \
if (EXPECTED(!in_hitlist(target, jmp_hitlist, jmp_hitlist_count))) { \
jmp_hitlist[jmp_hitlist_count++] = target; \
} else { \
break; \
}
void zend_optimizer_pass3(zend_op_array *op_array, zend_optimizer_ctx *ctx)
{
zend_op *opline;
zend_op *end;
zend_op *target;
zend_op **jmp_hitlist;
int jmp_hitlist_count;
ALLOCA_FLAG(use_heap);
jmp_hitlist = (zend_op**)do_alloca(sizeof(zend_op*)*op_array->last, use_heap);
opline = op_array->opcodes;
end = opline + op_array->last;
while (opline < end) {
switch (opline->opcode) {
case ZEND_JMP:
jmp_hitlist_count = 0;
target = ZEND_OP1_JMP_ADDR(opline);
while (1) {
if (target->opcode == ZEND_JMP) {
/* convert JMP L1 ... L1: JMP L2 to JMP L2 .. L1: JMP L2 */
target = ZEND_OP1_JMP_ADDR(target);
CHECK_LOOP(target);
} else if (target->opcode == ZEND_NOP) {
target = target + 1;
} else {
break;
}
ZEND_SET_OP_JMP_ADDR(opline, opline->op1, target);
}
if (target == opline + 1) {
/* convert L: JMP L+1 to NOP */
MAKE_NOP(opline);
} else if (target->opcode == ZEND_JMPZNZ) {
/* JMP L, L: JMPZNZ L1,L2 -> JMPZNZ L1,L2 */
*opline = *target;
if (opline->op1_type == IS_CONST) {
zval zv;
ZVAL_COPY(&zv, &ZEND_OP1_LITERAL(opline));
opline->op1.constant = zend_optimizer_add_literal(op_array, &zv);
}
/* Jump addresses may be encoded as offsets, recompute them. */
ZEND_SET_OP_JMP_ADDR(opline, opline->op2, ZEND_OP2_JMP_ADDR(target));
opline->extended_value = ZEND_OPLINE_TO_OFFSET(opline,
ZEND_OFFSET_TO_OPLINE(target, target->extended_value));
goto optimize_jmpznz;
} else if ((target->opcode == ZEND_RETURN ||
target->opcode == ZEND_RETURN_BY_REF ||
target->opcode == ZEND_GENERATOR_RETURN ||
target->opcode == ZEND_EXIT) &&
!(op_array->fn_flags & ZEND_ACC_HAS_FINALLY_BLOCK)) {
/* JMP L, L: RETURN to immediate RETURN */
*opline = *target;
if (opline->op1_type == IS_CONST) {
zval zv;
ZVAL_COPY(&zv, &ZEND_OP1_LITERAL(opline));
opline->op1.constant = zend_optimizer_add_literal(op_array, &zv);
}
} else if (opline > op_array->opcodes &&
((opline-1)->opcode == ZEND_JMPZ ||
(opline-1)->opcode == ZEND_JMPNZ)) {
if (ZEND_OP2_JMP_ADDR(opline-1) == target) {
/* JMPZ(X,L1), JMP(L1) -> NOP, JMP(L1) */
if ((opline-1)->op1_type == IS_CV) {
(opline-1)->opcode = ZEND_CHECK_VAR;
(opline-1)->op2.num = 0;
} else if ((opline-1)->op1_type & (IS_TMP_VAR|IS_VAR)) {
(opline-1)->opcode = ZEND_FREE;
(opline-1)->op2.num = 0;
} else {
MAKE_NOP(opline-1);
}
} else {
/* JMPZ(X,L1), JMP(L2) -> JMPZNZ(X,L1,L2) */
if ((opline-1)->opcode == ZEND_JMPZ) {
(opline-1)->extended_value = ZEND_OPLINE_TO_OFFSET((opline-1), target);
} else {
(opline-1)->extended_value = ZEND_OPLINE_TO_OFFSET((opline-1), ZEND_OP2_JMP_ADDR(opline-1));
ZEND_SET_OP_JMP_ADDR((opline-1), (opline-1)->op2, target);
}
(opline-1)->opcode = ZEND_JMPZNZ;
}
}
break;
case ZEND_JMP_SET:
case ZEND_COALESCE:
jmp_hitlist_count = 0;
target = ZEND_OP2_JMP_ADDR(opline);
while (1) {
if (target->opcode == ZEND_JMP) {
target = ZEND_OP1_JMP_ADDR(target);
CHECK_LOOP(target);
} else if (target->opcode == ZEND_NOP) {
target = target + 1;
} else {
break;
}
ZEND_SET_OP_JMP_ADDR(opline, opline->op2, target);
}
break;
case ZEND_JMPZ:
case ZEND_JMPNZ:
jmp_hitlist_count = 0;
target = ZEND_OP2_JMP_ADDR(opline);
while (1) {
if (target->opcode == ZEND_JMP) {
/* plain JMP */
/* JMPZ(X,L1), L1: JMP(L2) => JMPZ(X,L2), L1: JMP(L2) */
target = ZEND_OP1_JMP_ADDR(target);
CHECK_LOOP(target);
} else if (target->opcode == opline->opcode &&
SAME_VAR(opline->op1, target->op1)) {
/* same opcode and same var as this opcode */
/* JMPZ(X,L1), L1: JMPZ(X,L2) => JMPZ(X,L2), L1: JMPZ(X,L2) */
target = ZEND_OP2_JMP_ADDR(target);
CHECK_LOOP(target);
} else if (target->opcode == INV_COND(opline->opcode) &&
SAME_VAR(opline->op1, target->op1)) {
/* convert JMPZ(X,L1), L1: JMPNZ(X,L2) to
JMPZ(X,L1+1) */
target = target + 1;
} else if (target->opcode == ZEND_JMPZNZ &&
SAME_VAR(opline->op1, target->op1)) {
target = (opline->opcode == ZEND_JMPZ) ?
ZEND_OP2_JMP_ADDR(target) :
ZEND_OFFSET_TO_OPLINE(target, target->extended_value);
CHECK_LOOP(target);
} else if (target->opcode == ZEND_NOP) {
target = target + 1;
} else {
break;
}
ZEND_SET_OP_JMP_ADDR(opline, opline->op2, target);
}
/* convert L: JMPZ L+1 to NOP */
if (target == opline + 1) {
if (opline->op1_type == IS_CV) {
opline->opcode = ZEND_CHECK_VAR;
opline->op2.num = 0;
} else if (opline->op1_type & (IS_TMP_VAR|IS_VAR)) {
opline->opcode = ZEND_FREE;
opline->op2.num = 0;
} else {
MAKE_NOP(opline);
}
}
break;
case ZEND_JMPZ_EX:
case ZEND_JMPNZ_EX:
jmp_hitlist_count = 0;
target = ZEND_OP2_JMP_ADDR(opline);
while (1) {
if (target->opcode == ZEND_JMP) {
/* plain JMP */
/* JMPZ_EX(X,L1), L1: JMP(L2) => JMPZ_EX(X,L2), L1: JMP(L2) */
target = ZEND_OP1_JMP_ADDR(target);
CHECK_LOOP(target);
} else if (target->opcode == opline->opcode-3 &&
(SAME_VAR(target->op1, opline->result) ||
SAME_VAR(target->op1, opline->op1))) {
/* convert T=JMPZ_EX(X,L1), L1: JMPZ(T,L2) to
JMPZ_EX(X,L2) */
target = ZEND_OP2_JMP_ADDR(target);
CHECK_LOOP(target);
} else if (target->opcode == opline->opcode &&
target->result.var == opline->result.var &&
(SAME_VAR(target->op1, opline->result) ||
SAME_VAR(target->op1, opline->op1))) {
/* convert T=JMPZ_EX(X,L1), L1: T=JMPZ_EX(T,L2) to
JMPZ_EX(X,L2) */
target = ZEND_OP2_JMP_ADDR(target);
CHECK_LOOP(target);
} else if (target->opcode == ZEND_JMPZNZ &&
(SAME_VAR(target->op1, opline->result) ||
SAME_VAR(target->op1, opline->op1))) {
/* Check for JMPZNZ with same cond variable */
target = (opline->opcode == ZEND_JMPZ_EX) ?
ZEND_OP2_JMP_ADDR(target) :
ZEND_OFFSET_TO_OPLINE(target, target->extended_value);
CHECK_LOOP(target);
} else if (target->opcode == INV_EX_COND(opline->opcode) &&
(SAME_VAR(target->op1, opline->result) ||
SAME_VAR(target->op1, opline->op1))) {
/* convert T=JMPZ_EX(X,L1), L1: JMPNZ(T,L2) to
JMPZ_EX(X,L1+1) */
target = target + 1;
} else if (target->opcode == INV_EX_COND_EX(opline->opcode) &&
target->result.var == opline->result.var &&
(SAME_VAR(target->op1, opline->result) ||
SAME_VAR(target->op1, opline->op1))) {
/* convert T=JMPZ_EX(X,L1), L1: T=JMPNZ_EX(T,L2) to
JMPZ_EX(X,L1+1) */
target = target + 1;
} else if (target->opcode == ZEND_BOOL &&
(SAME_VAR(target->op1, opline->result) ||
SAME_VAR(target->op1, opline->op1))) {
/* convert Y = JMPZ_EX(X,L1), L1: Z = BOOL(Y) to
Z = JMPZ_EX(X,L1+1) */
/* NOTE: This optimization pattern is not safe, but works, */
/* because result of JMPZ_EX instruction */
/* is not used on the following path and */
/* should be used once on the branch path. */
/* */
/* The pattern works well only if jumps processed in */
/* direct order, otherwise it breaks JMPZ_EX */
/* sequences too early. */
opline->result.var = target->result.var;
target = target + 1;
CHECK_LOOP(target);
} else if (target->opcode == ZEND_NOP) {
target = target + 1;
} else {
break;
}
ZEND_SET_OP_JMP_ADDR(opline, opline->op2, target);
}
/* convert L: T = JMPZ_EX X,L+1 to T = BOOL(X) */
if (target == opline + 1) {
opline->opcode = ZEND_BOOL;
opline->op2.num = 0;
}
break;
case ZEND_JMPZNZ:
optimize_jmpznz:
jmp_hitlist_count = 0;
target = ZEND_OP2_JMP_ADDR(opline);
while (1) {
if (target->opcode == ZEND_JMP) {
/* JMPZNZ(X,L1,L2), L1: JMP(L3) => JMPZNZ(X,L3,L2), L1: JMP(L3) */
target = ZEND_OP1_JMP_ADDR(target);
CHECK_LOOP(target);
} else if ((target->opcode == ZEND_JMPZ || target->opcode == ZEND_JMPZNZ) &&
SAME_VAR(target->op1, opline->op1)) {
/* JMPZNZ(X, L1, L2), L1: JMPZ(X, L3) -> JMPZNZ(X, L3, L2) */
target = ZEND_OP2_JMP_ADDR(target);
CHECK_LOOP(target);
} else if (target->opcode == ZEND_JMPNZ &&
SAME_VAR(target->op1, opline->op1)) {
/* JMPZNZ(X, L1, L2), L1: X = JMPNZ(X, L3) -> JMPZNZ(X, L1+1, L2) */
target = target + 1;
} else if (target->opcode == ZEND_NOP) {
target = target + 1;
} else {
break;
}
ZEND_SET_OP_JMP_ADDR(opline, opline->op2, target);
}
jmp_hitlist_count = 0;
target = ZEND_OFFSET_TO_OPLINE(opline, opline->extended_value);
while (1) {
if (target->opcode == ZEND_JMP) {
/* JMPZNZ(X,L1,L2), L2: JMP(L3) => JMPZNZ(X,L1,L3), L2: JMP(L3) */
target = ZEND_OP1_JMP_ADDR(target);
CHECK_LOOP(target);
} else if (target->opcode == ZEND_JMPNZ &&
SAME_VAR(target->op1, opline->op1)) {
/* JMPZNZ(X, L1, L2), L1: X = JMPNZ(X, L3) -> JMPZNZ(X, L1+1, L2) */
target = ZEND_OP2_JMP_ADDR(target);
CHECK_LOOP(target);
} else if (target->opcode == ZEND_JMPZ &&
SAME_VAR(target->op1, opline->op1)) {
/* JMPZNZ(X, L1, L2), L1: JMPZ(X, L3) -> JMPZNZ(X, L3, L2) */
target = target + 1;
} else if (target->opcode == ZEND_JMPZNZ &&
SAME_VAR(target->op1, opline->op1)) {
/* JMPZNZ(X, L1, L2), L1: JMPZ(X, L3) -> JMPZNZ(X, L3, L2) */
target = ZEND_OFFSET_TO_OPLINE(target, target->extended_value);
CHECK_LOOP(target);
} else if (target->opcode == ZEND_NOP) {
target = target + 1;
} else {
break;
}
opline->extended_value = ZEND_OPLINE_TO_OFFSET(opline, target);
}
if (ZEND_OP2_JMP_ADDR(opline) == target &&
!(opline->op1_type & (IS_VAR|IS_TMP_VAR))) {
/* JMPZNZ(?,L,L) -> JMP(L) */
opline->opcode = ZEND_JMP;
ZEND_SET_OP_JMP_ADDR(opline, opline->op1, target);
SET_UNUSED(opline->op1);
SET_UNUSED(opline->op2);
opline->extended_value = 0;
}
/* Don't convert JMPZNZ back to JMPZ/JMPNZ, because the
following JMP is not removed yet. */
break;
}
opline++;
}
free_alloca(jmp_hitlist, use_heap);
}
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