/src/php-src/Zend/Optimizer/block_pass.c

Source
/*
   +----------------------------------------------------------------------+
   | Zend OPcache                                                         |
   +----------------------------------------------------------------------+
   | Copyright © The PHP Group and Contributors.                          |
   +----------------------------------------------------------------------+
   | This source file is subject to the Modified BSD License that is      |
   | bundled with this package in the file LICENSE, and is available      |
   | through the World Wide Web at <https://www.php.net/license/>.        |
   |                                                                      |
   | SPDX-License-Identifier: BSD-3-Clause                                |
   +----------------------------------------------------------------------+
   | Authors: Andi Gutmans <andi@php.net>                                 |
   |          Zeev Suraski <zeev@php.net>                                 |
   |          Stanislav Malyshev <stas@zend.com>                          |
   |          Dmitry Stogov <dmitry@php.net>                              |
   +----------------------------------------------------------------------+
*/

#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"
#include "zend_bitset.h"
#include "zend_cfg.h"
#include "zend_dump.h"

/* Checks if a constant (like "true") may be replaced by its value */
bool zend_optimizer_get_persistent_constant(zend_string *name, zval *result, bool copy)
{
  const zend_constant *c = zend_hash_find_ptr(EG(zend_constants), name);
  if (c) {
    if ((ZEND_CONSTANT_FLAGS(c) & CONST_PERSISTENT)
     && !(ZEND_CONSTANT_FLAGS(c) & CONST_DEPRECATED)
     && (!(ZEND_CONSTANT_FLAGS(c) & CONST_NO_FILE_CACHE)
      || !(CG(compiler_options) & ZEND_COMPILE_WITH_FILE_CACHE))) {
      ZVAL_COPY_VALUE(result, &c->value);
      if (copy) {
        Z_TRY_ADDREF_P(result);
      }
      return true;
    } else {
      return false;
    }
  }

  /* Special constants null/true/false can always be substituted. */
  c = zend_get_special_const(ZSTR_VAL(name), ZSTR_LEN(name));
  if (c) {
    ZVAL_COPY_VALUE(result, &c->value);
    return true;
  }
  return false;
}

/* Data dependencies macros */

#define VAR_SOURCE(op) Tsource[VAR_NUM(op.var)]
#define SET_VAR_SOURCE(opline) Tsource[VAR_NUM(opline->result.var)] = opline

static void strip_leading_nops(const zend_op_array *op_array, zend_basic_block *b)
{
  const zend_op *opcodes = op_array->opcodes;

  do {
    b->start++;
    b->len--;
  } while (b->len > 0 && opcodes[b->start].opcode == ZEND_NOP);
}

static void strip_nops(const zend_op_array *op_array, zend_basic_block *b)
{
  uint32_t i, j;

  if (b->len == 0) {
    return;
  }

  if (op_array->opcodes[b->start].opcode == ZEND_NOP) {
    strip_leading_nops(op_array, b);
  }

  if (b->len == 0) {
    return;
  }

  /* strip the inside NOPs */
  i = j = b->start + 1;
  while (i < b->start + b->len) {
    if (op_array->opcodes[i].opcode != ZEND_NOP) {
      if (i != j) {
        op_array->opcodes[j] = op_array->opcodes[i];
      }
      j++;
    }
    i++;
  }
  b->len = j - b->start;
  while (j < i) {
    MAKE_NOP(op_array->opcodes + j);
    j++;
  }
}

static uint32_t get_const_switch_target(const zend_cfg *cfg, const zend_op_array *op_array, const zend_basic_block *block, zend_op *opline, const zval *val) {
  HashTable *jumptable = Z_ARRVAL(ZEND_OP2_LITERAL(opline));
  zval *zv;
  if ((opline->opcode == ZEND_SWITCH_LONG && Z_TYPE_P(val) != IS_LONG)
      || (opline->opcode == ZEND_SWITCH_STRING && Z_TYPE_P(val) != IS_STRING)) {
    /* fallback to next block */
    return block->successors[block->successors_count - 1];
  }
  if (opline->opcode == ZEND_MATCH && Z_TYPE_P(val) != IS_LONG && Z_TYPE_P(val) != IS_STRING) {
    /* always jump to the default arm */
    return block->successors[block->successors_count - 1];
  }
  if (Z_TYPE_P(val) == IS_LONG) {
    zv = zend_hash_index_find(jumptable, Z_LVAL_P(val));
  } else {
    ZEND_ASSERT(Z_TYPE_P(val) == IS_STRING);
    zv = zend_hash_find(jumptable, Z_STR_P(val));
  }
  if (!zv) {
    /* default */
    return block->successors[block->successors_count - (opline->opcode == ZEND_MATCH ? 1 : 2)];
  }
  return cfg->map[ZEND_OFFSET_TO_OPLINE_NUM(op_array, opline, Z_LVAL_P(zv))];
}

static void zend_optimize_block(zend_basic_block *block, zend_op_array *op_array, zend_bitset used_ext, zend_cfg *cfg, zend_op **Tsource, uint32_t *opt_count)
{
  zend_op *opline, *src;
  zend_op *end, *last_op = NULL;

  if (block->len == 0) {
    return;
  }

  if (op_array->opcodes[block->start].opcode == ZEND_NOP) {
    /* remove leading NOPs */
    strip_leading_nops(op_array, block);
  }

  opline = op_array->opcodes + block->start;
  end = opline + block->len;
  while (opline < end) {
    /* Constant Propagation: strip X = QM_ASSIGN(const) */
    if (opline->op1_type == IS_TMP_VAR &&
        opline->opcode != ZEND_FREE) {
      src = VAR_SOURCE(opline->op1);
      if (src &&
          src->opcode == ZEND_QM_ASSIGN &&
          src->op1_type == IS_CONST
      ) {
        znode_op op1 = opline->op1;
        if (opline->opcode == ZEND_VERIFY_RETURN_TYPE) {
          COPY_NODE(opline->result, opline->op1);
          COPY_NODE(opline->op1, src->op1);
          VAR_SOURCE(op1) = NULL;
          MAKE_NOP(src);
          ++(*opt_count);
        } else {
          zval c;
          ZVAL_COPY(&c, &ZEND_OP1_LITERAL(src));
          if (opline->opcode != ZEND_CASE
           && opline->opcode != ZEND_CASE_STRICT
           && opline->opcode != ZEND_FETCH_LIST_R
           && opline->opcode != ZEND_SWITCH_LONG
           && opline->opcode != ZEND_SWITCH_STRING
           && opline->opcode != ZEND_MATCH
           && opline->opcode != ZEND_MATCH_ERROR
           && zend_optimizer_update_op1_const(op_array, opline, &c)) {
            VAR_SOURCE(op1) = NULL;
            if (opline->opcode != ZEND_JMP_NULL
             && !zend_bitset_in(used_ext, VAR_NUM(src->result.var))
             /* FETCH_W with ZEND_FETCH_GLOBAL_LOCK does not free op1, which will be used again. */
             && !(opline->opcode == ZEND_FETCH_W && (opline->extended_value & ZEND_FETCH_GLOBAL_LOCK))) {
              literal_dtor(&ZEND_OP1_LITERAL(src));
              MAKE_NOP(src);
            }
            ++(*opt_count);
          } else {
            zval_ptr_dtor_nogc(&c);
          }
        }
      }
    }

    /* Constant Propagation: strip X = QM_ASSIGN(const) */
    if (opline->op2_type == IS_TMP_VAR) {
      src = VAR_SOURCE(opline->op2);
      if (src &&
          src->opcode == ZEND_QM_ASSIGN &&
          src->op1_type == IS_CONST) {

        znode_op op2 = opline->op2;
        zval c;

        ZVAL_COPY(&c, &ZEND_OP1_LITERAL(src));
        if (zend_optimizer_update_op2_const(op_array, opline, &c)) {
          VAR_SOURCE(op2) = NULL;
          if (!zend_bitset_in(used_ext, VAR_NUM(src->result.var))) {
            literal_dtor(&ZEND_OP1_LITERAL(src));
            MAKE_NOP(src);
          }
          ++(*opt_count);
        } else {
          zval_ptr_dtor_nogc(&c);
        }
      }
    }

    switch (opline->opcode) {
      case ZEND_ECHO:
        if (opline->op1_type & (IS_TMP_VAR|IS_VAR)) {
          src = VAR_SOURCE(opline->op1);
          if (src &&
              src->opcode == ZEND_CAST &&
              src->extended_value == IS_STRING) {
            /* T = CAST(X, String), ECHO(T) => NOP, ECHO(X) */
            VAR_SOURCE(opline->op1) = NULL;
            COPY_NODE(opline->op1, src->op1);
            MAKE_NOP(src);
            ++(*opt_count);
          }
        } else if (opline->op1_type == IS_CONST &&
                   Z_TYPE(ZEND_OP1_LITERAL(opline)) != IS_DOUBLE) {
          if (last_op == opline - 1) {
            /* compress consecutive ECHO's.
             * Float to string conversion may be affected by current
             * locale setting.
             */
            size_t l, old_len;

            if (Z_TYPE(ZEND_OP1_LITERAL(opline)) != IS_STRING) {
              convert_to_string(&ZEND_OP1_LITERAL(opline));
            }
            if (Z_TYPE(ZEND_OP1_LITERAL(last_op)) != IS_STRING) {
              convert_to_string(&ZEND_OP1_LITERAL(last_op));
            }
            old_len = Z_STRLEN(ZEND_OP1_LITERAL(last_op));
            l = old_len + Z_STRLEN(ZEND_OP1_LITERAL(opline));
            if (!Z_REFCOUNTED(ZEND_OP1_LITERAL(last_op))) {
              zend_string *tmp = zend_string_alloc(l, 0);
              memcpy(ZSTR_VAL(tmp), Z_STRVAL(ZEND_OP1_LITERAL(last_op)), old_len);
              Z_STR(ZEND_OP1_LITERAL(last_op)) = tmp;
            } else {
              Z_STR(ZEND_OP1_LITERAL(last_op)) = zend_string_extend(Z_STR(ZEND_OP1_LITERAL(last_op)), l, 0);
            }
            Z_TYPE_INFO(ZEND_OP1_LITERAL(last_op)) = IS_STRING_EX;
            memcpy(Z_STRVAL(ZEND_OP1_LITERAL(last_op)) + old_len, Z_STRVAL(ZEND_OP1_LITERAL(opline)), Z_STRLEN(ZEND_OP1_LITERAL(opline)));
            Z_STRVAL(ZEND_OP1_LITERAL(last_op))[l] = '\0';
            zval_ptr_dtor_nogc(&ZEND_OP1_LITERAL(opline));
            ZVAL_STR(&ZEND_OP1_LITERAL(opline), zend_new_interned_string(Z_STR(ZEND_OP1_LITERAL(last_op))));
            ZVAL_NULL(&ZEND_OP1_LITERAL(last_op));
            MAKE_NOP(last_op);
            ++(*opt_count);
          }
          last_op = opline;
        }
        break;

      case ZEND_MATCH_ERROR:
        if (opline->op1_type & (IS_TMP_VAR|IS_VAR)) {
          src = VAR_SOURCE(opline->op1);
          VAR_SOURCE(opline->op1) = NULL;
        }
        break;

      case ZEND_FREE:
        /* Note: Only remove the source if the source is local to this block.
         * If it's not local, then the other blocks successors must also eventually either FREE or consume the temporary,
         * hence removing the temporary is not safe in the general case, especially when other consumers are not FREE.
         * A FREE may not be removed without also removing the source's result, because otherwise that would cause a memory leak. */
        if (opline->extended_value == ZEND_FREE_VOID_CAST) {
          /* Keep the ZEND_FREE opcode alive. */
        } else if (opline->op1_type == IS_TMP_VAR) {
          src = VAR_SOURCE(opline->op1);
          if (src) {
            switch (src->opcode) {
              case ZEND_BOOL:
              case ZEND_BOOL_NOT:
                /* T = BOOL(X), FREE(T) => T = BOOL(X) */
                /* The remaining BOOL is removed by a separate optimization */
                /* The source is a bool, no source removals take place, so this may be done non-locally. */
                VAR_SOURCE(opline->op1) = NULL;
                MAKE_NOP(opline);
                ++(*opt_count);
                break;
              case ZEND_QM_ASSIGN:
                if (src < op_array->opcodes + block->start) {
                  break;
                }
                src->result_type = IS_UNUSED;
                VAR_SOURCE(opline->op1) = NULL;
                MAKE_NOP(opline);
                ++(*opt_count);
                if (src->op1_type & (IS_VAR|IS_TMP_VAR)) {
                  src->opcode = ZEND_FREE;
                } else if (src->op1_type == IS_CONST) {
                  MAKE_NOP(src);
                } else if (src->op1_type == IS_CV) {
                  src->opcode = ZEND_CHECK_VAR;
                  SET_UNUSED(src->result);
                }
                break;
              default:
                if (!zend_op_may_elide_result(src->opcode)) {
                  break;
                }
                if (src < op_array->opcodes + block->start) {
                  break;
                }
                src->result_type = IS_UNUSED;
                VAR_SOURCE(opline->op1) = NULL;
                MAKE_NOP(opline);
                ++(*opt_count);
                break;
            }
          }
        } else if (opline->op1_type == IS_VAR) {
          src = VAR_SOURCE(opline->op1);
          /* V = OP, FREE(V) => OP. NOP */
          if (src >= op_array->opcodes + block->start &&
              src->opcode != ZEND_FETCH_R &&
              src->opcode != ZEND_FETCH_STATIC_PROP_R &&
              src->opcode != ZEND_FETCH_DIM_R &&
              src->opcode != ZEND_FETCH_OBJ_R &&
              src->opcode != ZEND_NEW &&
              src->opcode != ZEND_FETCH_THIS) {
            src->result_type = IS_UNUSED;
            MAKE_NOP(opline);
            ++(*opt_count);
            if (src->opcode == ZEND_QM_ASSIGN) {
              if (src->op1_type & (IS_VAR|IS_TMP_VAR)) {
                src->opcode = ZEND_FREE;
              } else {
                MAKE_NOP(src);
              }
            }
          }
        }
        break;

      case ZEND_FETCH_LIST_R:
      case ZEND_FETCH_LIST_W:
        if (opline->op1_type & (IS_TMP_VAR|IS_VAR)) {
          /* LIST variable will be deleted later by FREE */
          Tsource[VAR_NUM(opline->op1.var)] = NULL;
        }
        break;

      case ZEND_SWITCH_LONG:
      case ZEND_SWITCH_STRING:
      case ZEND_MATCH:
        if (opline->op1_type & (IS_TMP_VAR|IS_VAR)) {
          /* SWITCH variable will be deleted later by FREE, so we can't optimize it */
          Tsource[VAR_NUM(opline->op1.var)] = NULL;
          break;
        }
        if (opline->op1_type == IS_CONST) {
          uint32_t target = get_const_switch_target(cfg, op_array, block, opline, &ZEND_OP1_LITERAL(opline));
          literal_dtor(&ZEND_OP1_LITERAL(opline));
          literal_dtor(&ZEND_OP2_LITERAL(opline));
          opline->opcode = ZEND_JMP;
          opline->op1_type = IS_UNUSED;
          opline->op2_type = IS_UNUSED;
          block->successors_count = 1;
          block->successors[0] = target;
        }
        break;

      case ZEND_EXT_STMT:
        if (opline->op1_type & (IS_TMP_VAR|IS_VAR)) {
          /* Variable will be deleted later by FREE, so we can't optimize it */
          Tsource[VAR_NUM(opline->op1.var)] = NULL;
          break;
        }
        break;

      case ZEND_CASE:
      case ZEND_CASE_STRICT:
      case ZEND_COPY_TMP:
        if (opline->op1_type & (IS_TMP_VAR|IS_VAR)) {
          /* Variable will be deleted later by FREE, so we can't optimize it */
          Tsource[VAR_NUM(opline->op1.var)] = NULL;
          break;
        }
        if (opline->op1_type == IS_CONST &&
            opline->op2_type == IS_CONST) {
          goto optimize_constant_binary_op;
        }
            /*
             * CASE(TRUE, X)       => BOOL(X)
             * CASE(FALSE, X)      => BOOL_NOT(X)
             */
        if (opline->op1_type == IS_CONST &&
          (Z_TYPE(ZEND_OP1_LITERAL(opline)) == IS_FALSE ||
           Z_TYPE(ZEND_OP1_LITERAL(opline)) == IS_TRUE)) {
          /* Optimization of comparison with "null" is not safe,
           * because ("0" == null) is not equal to !("0")
           */
          opline->opcode =
            ((opline->opcode != ZEND_IS_NOT_EQUAL) == ((Z_TYPE(ZEND_OP1_LITERAL(opline))) == IS_TRUE)) ?
            ZEND_BOOL : ZEND_BOOL_NOT;
          COPY_NODE(opline->op1, opline->op2);
          SET_UNUSED(opline->op2);
          ++(*opt_count);
          goto optimize_bool;
        } else if (opline->op2_type == IS_CONST &&
                   (Z_TYPE(ZEND_OP2_LITERAL(opline)) == IS_FALSE ||
                    Z_TYPE(ZEND_OP2_LITERAL(opline)) == IS_TRUE)) {
          /* Optimization of comparison with "null" is not safe,
           * because ("0" == null) is not equal to !("0")
           */
          opline->opcode =
            ((opline->opcode != ZEND_IS_NOT_EQUAL) == ((Z_TYPE(ZEND_OP2_LITERAL(opline))) == IS_TRUE)) ?
            ZEND_BOOL : ZEND_BOOL_NOT;
          SET_UNUSED(opline->op2);
          ++(*opt_count);
          goto optimize_bool;
        }
        break;

      case ZEND_IS_EQUAL:
      case ZEND_IS_NOT_EQUAL:
        if (opline->op1_type == IS_CONST &&
          opline->op2_type == IS_CONST) {
          goto optimize_constant_binary_op;
        }
        /* IS_EQ(TRUE, X)      => BOOL(X)
         * IS_EQ(FALSE, X)     => BOOL_NOT(X)
         * IS_NOT_EQ(TRUE, X)  => BOOL_NOT(X)
         * IS_NOT_EQ(FALSE, X) => BOOL(X)
         * Those optimizations are not safe if the other operand ends up being NAN
         * as BOOL/BOOL_NOT will warn, while IS_EQUAL/IS_NOT_EQUAL do not.
         */
        break;
      case ZEND_IS_IDENTICAL:
        if (opline->op1_type == IS_CONST &&
          opline->op2_type == IS_CONST) {
          goto optimize_constant_binary_op;
        }

        if (opline->op1_type == IS_CONST &&
          (Z_TYPE(ZEND_OP1_LITERAL(opline)) <= IS_TRUE && Z_TYPE(ZEND_OP1_LITERAL(opline)) >= IS_NULL)) {
          /* IS_IDENTICAL(TRUE, T)  => TYPE_CHECK(T, TRUE)
           * IS_IDENTICAL(FALSE, T) => TYPE_CHECK(T, FALSE)
           * IS_IDENTICAL(NULL, T)  => TYPE_CHECK(T, NULL)
           */
          opline->opcode = ZEND_TYPE_CHECK;
          opline->extended_value = (1 << Z_TYPE(ZEND_OP1_LITERAL(opline)));
          COPY_NODE(opline->op1, opline->op2);
          SET_UNUSED(opline->op2);
          ++(*opt_count);
          goto optimize_type_check;
        } else if (opline->op2_type == IS_CONST &&
          (Z_TYPE(ZEND_OP2_LITERAL(opline)) <= IS_TRUE && Z_TYPE(ZEND_OP2_LITERAL(opline)) >= IS_NULL)) {
          /* IS_IDENTICAL(T, TRUE)  => TYPE_CHECK(T, TRUE)
           * IS_IDENTICAL(T, FALSE) => TYPE_CHECK(T, FALSE)
           * IS_IDENTICAL(T, NULL)  => TYPE_CHECK(T, NULL)
           */
          opline->opcode = ZEND_TYPE_CHECK;
          opline->extended_value = (1 << Z_TYPE(ZEND_OP2_LITERAL(opline)));
          SET_UNUSED(opline->op2);
          ++(*opt_count);
          goto optimize_type_check;
        }
        break;
      case ZEND_TYPE_CHECK:
optimize_type_check:
        if (opline->extended_value == (1 << IS_TRUE) || opline->extended_value == (1 << IS_FALSE)) {
          if (opline->op1_type == IS_TMP_VAR &&
            !zend_bitset_in(used_ext, VAR_NUM(opline->op1.var))) {
            src = VAR_SOURCE(opline->op1);

            if (src) {
              switch (src->opcode) {
                case ZEND_BOOL:
                case ZEND_BOOL_NOT:
                  /* T = BOOL(X)     + TYPE_CHECK(T, TRUE)  -> BOOL(X), NOP
                   * T = BOOL(X)     + TYPE_CHECK(T, FALSE) -> BOOL_NOT(X), NOP
                   * T = BOOL_NOT(X) + TYPE_CHECK(T, TRUE)  -> BOOL_NOT(X), NOP
                   * T = BOOL_NOT(X) + TYPE_CHECK(T, FALSE) -> BOOL(X), NOP
                   */
                  src->opcode =
                    ((src->opcode == ZEND_BOOL) == (opline->extended_value == (1 << IS_TRUE))) ?
                    ZEND_BOOL : ZEND_BOOL_NOT;
                  COPY_NODE(src->result, opline->result);
                  SET_VAR_SOURCE(src);
                  MAKE_NOP(opline);
                  ++(*opt_count);
                  break;
              }
            }
          }
        }
        break;
  
      case ZEND_BOOL:
      case ZEND_BOOL_NOT:
      optimize_bool:
        if (opline->op1_type == IS_CONST) {
          goto optimize_const_unary_op;
        }
        if (opline->op1_type == IS_TMP_VAR &&
            !zend_bitset_in(used_ext, VAR_NUM(opline->op1.var))) {
          src = VAR_SOURCE(opline->op1);
          if (src) {
            switch (src->opcode) {
              case ZEND_BOOL_NOT:
                /* T = BOOL_NOT(X) + BOOL(T) -> NOP, BOOL_NOT(X) */
                VAR_SOURCE(opline->op1) = NULL;
                COPY_NODE(opline->op1, src->op1);
                opline->opcode = (opline->opcode == ZEND_BOOL) ? ZEND_BOOL_NOT : ZEND_BOOL;
                MAKE_NOP(src);
                ++(*opt_count);
                goto optimize_bool;
              case ZEND_BOOL:
                /* T = BOOL(X) + BOOL(T) -> NOP, BOOL(X) */
                VAR_SOURCE(opline->op1) = NULL;
                COPY_NODE(opline->op1, src->op1);
                MAKE_NOP(src);
                ++(*opt_count);
                goto optimize_bool;
              case ZEND_IS_EQUAL:
                if (opline->opcode == ZEND_BOOL_NOT) {
                  src->opcode = ZEND_IS_NOT_EQUAL;
                }
                COPY_NODE(src->result, opline->result);
                SET_VAR_SOURCE(src);
                MAKE_NOP(opline);
                ++(*opt_count);
                break;
              case ZEND_IS_NOT_EQUAL:
                if (opline->opcode == ZEND_BOOL_NOT) {
                  src->opcode = ZEND_IS_EQUAL;
                }
                COPY_NODE(src->result, opline->result);
                SET_VAR_SOURCE(src);
                MAKE_NOP(opline);
                ++(*opt_count);
                break;
              case ZEND_IS_IDENTICAL:
                if (opline->opcode == ZEND_BOOL_NOT) {
                  src->opcode = ZEND_IS_NOT_IDENTICAL;
                }
                COPY_NODE(src->result, opline->result);
                SET_VAR_SOURCE(src);
                MAKE_NOP(opline);
                ++(*opt_count);
                break;
              case ZEND_IS_NOT_IDENTICAL:
                if (opline->opcode == ZEND_BOOL_NOT) {
                  src->opcode = ZEND_IS_IDENTICAL;
                }
                COPY_NODE(src->result, opline->result);
                SET_VAR_SOURCE(src);
                MAKE_NOP(opline);
                ++(*opt_count);
                break;
              case ZEND_IS_SMALLER:
                if (opline->opcode == ZEND_BOOL_NOT) {
                  uint8_t tmp_type;
                  uint32_t tmp;

                  src->opcode = ZEND_IS_SMALLER_OR_EQUAL;
                  tmp_type = src->op1_type;
                  src->op1_type = src->op2_type;
                  src->op2_type = tmp_type;
                  tmp = src->op1.num;
                  src->op1.num = src->op2.num;
                  src->op2.num = tmp;
                }
                COPY_NODE(src->result, opline->result);
                SET_VAR_SOURCE(src);
                MAKE_NOP(opline);
                ++(*opt_count);
                break;
              case ZEND_IS_SMALLER_OR_EQUAL:
                if (opline->opcode == ZEND_BOOL_NOT) {
                  uint8_t tmp_type;
                  uint32_t tmp;

                  src->opcode = ZEND_IS_SMALLER;
                  tmp_type = src->op1_type;
                  src->op1_type = src->op2_type;
                  src->op2_type = tmp_type;
                  tmp = src->op1.num;
                  src->op1.num = src->op2.num;
                  src->op2.num = tmp;
                }
                COPY_NODE(src->result, opline->result);
                SET_VAR_SOURCE(src);
                MAKE_NOP(opline);
                ++(*opt_count);
                break;
              case ZEND_ISSET_ISEMPTY_CV:
              case ZEND_ISSET_ISEMPTY_VAR:
              case ZEND_ISSET_ISEMPTY_DIM_OBJ:
              case ZEND_ISSET_ISEMPTY_PROP_OBJ:
              case ZEND_ISSET_ISEMPTY_STATIC_PROP:
              case ZEND_INSTANCEOF:
              case ZEND_TYPE_CHECK:
              case ZEND_DEFINED:
              case ZEND_IN_ARRAY:
              case ZEND_ARRAY_KEY_EXISTS:
                if (opline->opcode == ZEND_BOOL_NOT) {
                  break;
                }
                COPY_NODE(src->result, opline->result);
                SET_VAR_SOURCE(src);
                MAKE_NOP(opline);
                ++(*opt_count);
                break;
            }
          }
        }
        break;

      case ZEND_JMPZ:
      case ZEND_JMPNZ:
          while (1) {
          if (opline->op1_type == IS_CONST) {
            ++(*opt_count);
            block->successors_count = 1;
            if (zend_is_true(&ZEND_OP1_LITERAL(opline)) ==
                (opline->opcode == ZEND_JMPZ)) {

              MAKE_NOP(opline);
              block->successors[0] = block->successors[1];
              block->len--;
              cfg->blocks[block->successors[0]].flags |= ZEND_BB_FOLLOW;
              break;
            } else {
              zend_basic_block *next = cfg->blocks + block->successors[1];

              next->flags &= ~ZEND_BB_FOLLOW;
              if (!(next->flags & (ZEND_BB_TARGET|ZEND_BB_PROTECTED))) {
                next->flags &= ~ZEND_BB_REACHABLE;
              }
              opline->opcode = ZEND_JMP;
              COPY_NODE(opline->op1, opline->op2);
              break;
            }
          } else if (opline->op1_type == IS_TMP_VAR &&
                     !zend_bitset_in(used_ext, VAR_NUM(opline->op1.var))) {
            src = VAR_SOURCE(opline->op1);
            if (src && (src->op1_type != IS_VAR)) {
              if (src->opcode == ZEND_BOOL_NOT) {
                VAR_SOURCE(opline->op1) = NULL;
                COPY_NODE(opline->op1, src->op1);
                /* T = BOOL_NOT(X) + JMPZ(T) -> NOP, JMPNZ(X) */
                opline->opcode = INV_COND(opline->opcode);
                MAKE_NOP(src);
                ++(*opt_count);
                continue;
              } else if (src->opcode == ZEND_BOOL ||
                         src->opcode == ZEND_QM_ASSIGN) {
                VAR_SOURCE(opline->op1) = NULL;
                COPY_NODE(opline->op1, src->op1);
                MAKE_NOP(src);
                ++(*opt_count);
                continue;
              }
            }
          }
          break;
        }
        break;

      case ZEND_JMPZ_EX:
      case ZEND_JMPNZ_EX:
        while (1) {
          if (opline->op1_type == IS_CONST) {
            bool is_jmpz_ex = opline->opcode == ZEND_JMPZ_EX;
            if (zend_is_true(&ZEND_OP1_LITERAL(opline)) == is_jmpz_ex) {

              ++(*opt_count);
              opline->opcode = ZEND_QM_ASSIGN;
              zval_ptr_dtor_nogc(&ZEND_OP1_LITERAL(opline));
              ZVAL_BOOL(&ZEND_OP1_LITERAL(opline), is_jmpz_ex);
              opline->op2.num = 0;
              block->successors_count = 1;
              block->successors[0] = block->successors[1];
              cfg->blocks[block->successors[0]].flags |= ZEND_BB_FOLLOW;
              break;
            }
          } else if (opline->op1_type == IS_TMP_VAR &&
                     (!zend_bitset_in(used_ext, VAR_NUM(opline->op1.var)) ||
                      opline->result.var == opline->op1.var)) {
            src = VAR_SOURCE(opline->op1);
            if (src && (src->op1_type != IS_VAR)) {
              if (src->opcode == ZEND_BOOL ||
                  src->opcode == ZEND_QM_ASSIGN) {
                VAR_SOURCE(opline->op1) = NULL;
                COPY_NODE(opline->op1, src->op1);
                MAKE_NOP(src);
                ++(*opt_count);
                continue;
              }
            }
          }
          break;
        }
        break;

      case ZEND_CONCAT:
      case ZEND_FAST_CONCAT:
        if (opline->op1_type == IS_CONST &&
            opline->op2_type == IS_CONST) {
          goto optimize_constant_binary_op;
        }

        if (opline->op2_type == IS_CONST &&
            opline->op1_type == IS_TMP_VAR) {

          src = VAR_SOURCE(opline->op1);
            if (src &&
              (src->opcode == ZEND_CONCAT ||
               src->opcode == ZEND_FAST_CONCAT) &&
              src->op2_type == IS_CONST) {
            /* compress consecutive CONCATs */
            size_t l, old_len;

            if (Z_TYPE(ZEND_OP2_LITERAL(opline)) != IS_STRING) {
              convert_to_string(&ZEND_OP2_LITERAL(opline));
            }
            if (Z_TYPE(ZEND_OP2_LITERAL(src)) != IS_STRING) {
              convert_to_string(&ZEND_OP2_LITERAL(src));
            }

            VAR_SOURCE(opline->op1) = NULL;
            COPY_NODE(opline->op1, src->op1);
            old_len = Z_STRLEN(ZEND_OP2_LITERAL(src));
            l = old_len + Z_STRLEN(ZEND_OP2_LITERAL(opline));
            if (!Z_REFCOUNTED(ZEND_OP2_LITERAL(src))) {
              zend_string *tmp = zend_string_alloc(l, 0);
              memcpy(ZSTR_VAL(tmp), Z_STRVAL(ZEND_OP2_LITERAL(src)), old_len);
              Z_STR(ZEND_OP2_LITERAL(src)) = tmp;
            } else {
              Z_STR(ZEND_OP2_LITERAL(src)) = zend_string_extend(Z_STR(ZEND_OP2_LITERAL(src)), l, 0);
            }
            Z_TYPE_INFO(ZEND_OP2_LITERAL(src)) = IS_STRING_EX;
            memcpy(Z_STRVAL(ZEND_OP2_LITERAL(src)) + old_len, Z_STRVAL(ZEND_OP2_LITERAL(opline)), Z_STRLEN(ZEND_OP2_LITERAL(opline)));
            Z_STRVAL(ZEND_OP2_LITERAL(src))[l] = '\0';
            zval_ptr_dtor_str(&ZEND_OP2_LITERAL(opline));
            ZVAL_STR(&ZEND_OP2_LITERAL(opline), zend_new_interned_string(Z_STR(ZEND_OP2_LITERAL(src))));
            ZVAL_NULL(&ZEND_OP2_LITERAL(src));
            MAKE_NOP(src);
            ++(*opt_count);
          }
        }

        if (opline->op1_type & (IS_TMP_VAR|IS_VAR)) {
          src = VAR_SOURCE(opline->op1);
          if (src &&
              src->opcode == ZEND_CAST &&
              src->extended_value == IS_STRING &&
              src->op1_type != IS_CONST) {
            /* convert T1 = CAST(STRING, X), T2 = CONCAT(T1, Y) to T2 = CONCAT(X,Y) */
            VAR_SOURCE(opline->op1) = NULL;
            COPY_NODE(opline->op1, src->op1);
            MAKE_NOP(src);
            ++(*opt_count);
          }
              }
        if (opline->op2_type & (IS_TMP_VAR|IS_VAR)) {
          src = VAR_SOURCE(opline->op2);
          if (src &&
              src->opcode == ZEND_CAST &&
              src->extended_value == IS_STRING &&
              src->op1_type != IS_CONST) {
            /* convert T1 = CAST(STRING, X), T2 = CONCAT(Y, T1) to T2 = CONCAT(Y,X) */
            VAR_SOURCE(opline->op2) = NULL;
            COPY_NODE(opline->op2, src->op1);
            MAKE_NOP(src);
            ++(*opt_count);
          }
        }
        if (opline->op1_type == IS_CONST &&
            Z_TYPE(ZEND_OP1_LITERAL(opline)) == IS_STRING &&
            Z_STRLEN(ZEND_OP1_LITERAL(opline)) == 0) {
          /* convert CONCAT('', X) => CAST(STRING, X) */
          literal_dtor(&ZEND_OP1_LITERAL(opline));
          opline->opcode = ZEND_CAST;
          opline->extended_value = IS_STRING;
          COPY_NODE(opline->op1, opline->op2);
          opline->op2_type = IS_UNUSED;
          opline->op2.var = 0;
          ++(*opt_count);
        } else if (opline->op2_type == IS_CONST &&
                 Z_TYPE(ZEND_OP2_LITERAL(opline)) == IS_STRING &&
                 Z_STRLEN(ZEND_OP2_LITERAL(opline)) == 0) {
          /* convert CONCAT(X, '') => CAST(STRING, X) */
          literal_dtor(&ZEND_OP2_LITERAL(opline));
          opline->opcode = ZEND_CAST;
          opline->extended_value = IS_STRING;
          opline->op2_type = IS_UNUSED;
          opline->op2.var = 0;
          ++(*opt_count);
        } else if (opline->opcode == ZEND_CONCAT &&
                   (opline->op1_type == IS_CONST ||
                    (opline->op1_type == IS_TMP_VAR &&
                     VAR_SOURCE(opline->op1) &&
                     (VAR_SOURCE(opline->op1)->opcode == ZEND_FAST_CONCAT ||
                      VAR_SOURCE(opline->op1)->opcode == ZEND_ROPE_END ||
                      VAR_SOURCE(opline->op1)->opcode == ZEND_FETCH_CONSTANT ||
                      VAR_SOURCE(opline->op1)->opcode == ZEND_FETCH_CLASS_CONSTANT))) &&
                   (opline->op2_type == IS_CONST ||
                    (opline->op2_type == IS_TMP_VAR &&
                     VAR_SOURCE(opline->op2) &&
                     (VAR_SOURCE(opline->op2)->opcode == ZEND_FAST_CONCAT ||
                      VAR_SOURCE(opline->op2)->opcode == ZEND_ROPE_END ||
                      VAR_SOURCE(opline->op2)->opcode == ZEND_FETCH_CONSTANT ||
                      VAR_SOURCE(opline->op2)->opcode == ZEND_FETCH_CLASS_CONSTANT)))) {
          opline->opcode = ZEND_FAST_CONCAT;
          ++(*opt_count);
        }
        break;

      case ZEND_ADD:
      case ZEND_SUB:
      case ZEND_MUL:
      case ZEND_DIV:
      case ZEND_MOD:
      case ZEND_SL:
      case ZEND_SR:
      case ZEND_IS_SMALLER:
      case ZEND_IS_SMALLER_OR_EQUAL:
      case ZEND_IS_NOT_IDENTICAL:
      case ZEND_BOOL_XOR:
      case ZEND_BW_OR:
      case ZEND_BW_AND:
      case ZEND_BW_XOR:
        if (opline->op1_type == IS_CONST &&
            opline->op2_type == IS_CONST) {
          /* evaluate constant expressions */
          zval result;

optimize_constant_binary_op:
          if (zend_optimizer_eval_binary_op(&result, opline->opcode, &ZEND_OP1_LITERAL(opline), &ZEND_OP2_LITERAL(opline)) == SUCCESS) {
            literal_dtor(&ZEND_OP1_LITERAL(opline));
            literal_dtor(&ZEND_OP2_LITERAL(opline));
            opline->opcode = ZEND_QM_ASSIGN;
            SET_UNUSED(opline->op2);
            zend_optimizer_update_op1_const(op_array, opline, &result);
            ++(*opt_count);
          }
        }
        break;

      case ZEND_BW_NOT:
        if (opline->op1_type == IS_CONST) {
          /* evaluate constant unary ops */
          zval result;

optimize_const_unary_op:
          if (zend_optimizer_eval_unary_op(&result, opline->opcode, &ZEND_OP1_LITERAL(opline)) == SUCCESS) {
            literal_dtor(&ZEND_OP1_LITERAL(opline));
            opline->opcode = ZEND_QM_ASSIGN;
            zend_optimizer_update_op1_const(op_array, opline, &result);
            ++(*opt_count);
          }
        }
        break;

      case ZEND_CAST:
        if (opline->op1_type == IS_CONST) {
          /* cast of constant operand */
          zval result;

          if (zend_optimizer_eval_cast(&result, opline->extended_value, &ZEND_OP1_LITERAL(opline)) == SUCCESS) {
            literal_dtor(&ZEND_OP1_LITERAL(opline));
            opline->opcode = ZEND_QM_ASSIGN;
            opline->extended_value = 0;
            zend_optimizer_update_op1_const(op_array, opline, &result);
            ++(*opt_count);
          }
        }
        break;

      case ZEND_STRLEN:
        if (opline->op1_type == IS_CONST) {
          zval result;

          if (zend_optimizer_eval_strlen(&result, &ZEND_OP1_LITERAL(opline)) == SUCCESS) {
            literal_dtor(&ZEND_OP1_LITERAL(opline));
            opline->opcode = ZEND_QM_ASSIGN;
            zend_optimizer_update_op1_const(op_array, opline, &result);
            ++(*opt_count);
          }
        }
        break;

      case ZEND_RETURN:
        if (opline->op1_type == IS_TMP_VAR) {
          src = VAR_SOURCE(opline->op1);
          if (src && src->opcode == ZEND_QM_ASSIGN) {
            zend_op *op = src + 1;
            bool optimize = true;

            while (op < opline) {
              if ((op->op1_type == opline->op1_type
                && op->op1.var == opline->op1.var)
               || (op->op2_type == opline->op1_type
                && op->op2.var == opline->op1.var)) {
                optimize = false;
                break;
              }
              op++;
            }

            if (optimize) {
              /* T = QM_ASSIGN(X), RETURN(T) to NOP, RETURN(X) */
              VAR_SOURCE(opline->op1) = NULL;
              COPY_NODE(opline->op1, src->op1);
              MAKE_NOP(src);
              ++(*opt_count);
            }
          }
        }
        break;

      case ZEND_QM_ASSIGN:
        if (opline->op1_type == opline->result_type &&
            opline->op1.var == opline->result.var) {
          /* strip T = QM_ASSIGN(T) */
          MAKE_NOP(opline);
          ++(*opt_count);
        } else if (opline->op1_type == IS_TMP_VAR &&
                   opline->result_type == IS_TMP_VAR &&
                   !zend_bitset_in(used_ext, VAR_NUM(opline->op1.var))) {
          /* T1 = ..., T2 = QM_ASSIGN(T1) to T2 = ..., NOP */
          src = VAR_SOURCE(opline->op1);
          if (src &&
            src->opcode != ZEND_COPY_TMP &&
            /* See gh20628_borked_live_range_calc.phpt. */
            src->opcode != ZEND_NEW &&
            src->opcode != ZEND_ADD_ARRAY_ELEMENT &&
            src->opcode != ZEND_ADD_ARRAY_UNPACK &&
            (src->opcode != ZEND_DECLARE_LAMBDA_FUNCTION ||
             src == opline -1)) {
            src->result.var = opline->result.var;
            VAR_SOURCE(opline->op1) = NULL;
            VAR_SOURCE(opline->result) = src;
            MAKE_NOP(opline);
            ++(*opt_count);
          }
        }
        break;
    }

    /* get variable source */
    if (opline->result_type & (IS_VAR|IS_TMP_VAR)) {
      SET_VAR_SOURCE(opline);
    }
    opline++;
  }
}

/* Rebuild plain (optimized) op_array from CFG */
static void assemble_code_blocks(const zend_cfg *cfg, zend_op_array *op_array, zend_optimizer_ctx *ctx)
{
  zend_basic_block *blocks = cfg->blocks;
  const zend_basic_block *end = blocks + cfg->blocks_count;
  zend_basic_block *b;
  zend_op *new_opcodes;
  zend_op *opline;
  uint32_t len = 0;

  for (b = blocks; b < end; b++) {
    if (b->len == 0) {
      continue;
    }
    if (b->flags & (ZEND_BB_REACHABLE|ZEND_BB_UNREACHABLE_FREE)) {
      opline = op_array->opcodes + b->start + b->len - 1;
      if (opline->opcode == ZEND_JMP) {
        const zend_basic_block *next = b + 1;

        while (next < end && !(next->flags & ZEND_BB_REACHABLE)) {
          next++;
        }
        if (next < end && next == blocks + b->successors[0]) {
          /* JMP to the next block - strip it */
          MAKE_NOP(opline);
          b->len--;
        }
      } else if (b->len == 1 && opline->opcode == ZEND_NOP) {
        /* skip empty block */
        b->len--;
      }
      len += b->len;
    } else {
      /* this block will not be used, delete all constants there */
      const zend_op *op = op_array->opcodes + b->start;
      const zend_op *last_op = op + b->len;
      for (; op < last_op; op++) {
        if (op->op1_type == IS_CONST) {
          literal_dtor(&ZEND_OP1_LITERAL(op));
        }
        if (op->op2_type == IS_CONST) {
          literal_dtor(&ZEND_OP2_LITERAL(op));
        }
      }
    }
  }

  new_opcodes = emalloc(len * sizeof(zend_op));
  opline = new_opcodes;

  /* Copy code of reachable blocks into a single buffer */
  for (b = blocks; b < end; b++) {
    if (b->flags & (ZEND_BB_REACHABLE|ZEND_BB_UNREACHABLE_FREE)) {
      memcpy(opline, op_array->opcodes + b->start, b->len * sizeof(zend_op));
      b->start = opline - new_opcodes;
      opline += b->len;
    }
  }

  /* adjust jump targets */
  efree(op_array->opcodes);
  op_array->opcodes = new_opcodes;
  op_array->last = len;

  for (b = blocks; b < end; b++) {
    if (!(b->flags & ZEND_BB_REACHABLE) || b->len == 0) {
      continue;
    }
    opline = op_array->opcodes + b->start + b->len - 1;
    switch (opline->opcode) {
      case ZEND_FAST_CALL:
      case ZEND_JMP:
        ZEND_SET_OP_JMP_ADDR(opline, opline->op1, new_opcodes + blocks[b->successors[0]].start);
        break;
      case ZEND_JMPZ:
      case ZEND_JMPNZ:
      case ZEND_JMPZ_EX:
      case ZEND_JMPNZ_EX:
      case ZEND_FE_RESET_R:
      case ZEND_FE_RESET_RW:
      case ZEND_JMP_SET:
      case ZEND_COALESCE:
      case ZEND_ASSERT_CHECK:
      case ZEND_JMP_NULL:
      case ZEND_BIND_INIT_STATIC_OR_JMP:
      case ZEND_JMP_FRAMELESS:
        ZEND_SET_OP_JMP_ADDR(opline, opline->op2, new_opcodes + blocks[b->successors[0]].start);
        break;
      case ZEND_CATCH:
        if (!(opline->extended_value & ZEND_LAST_CATCH)) {
          ZEND_SET_OP_JMP_ADDR(opline, opline->op2, new_opcodes + blocks[b->successors[0]].start);
        }
        break;
      case ZEND_FE_FETCH_R:
      case ZEND_FE_FETCH_RW:
        opline->extended_value = ZEND_OPLINE_TO_OFFSET(opline, new_opcodes + blocks[b->successors[0]].start);
        break;
      case ZEND_SWITCH_LONG:
      case ZEND_SWITCH_STRING:
      case ZEND_MATCH:
      {
        const HashTable *jumptable = Z_ARRVAL(ZEND_OP2_LITERAL(opline));
        zval *zv;
        uint32_t s = 0;
        ZEND_ASSERT(b->successors_count == (opline->opcode == ZEND_MATCH ? 1 : 2) + zend_hash_num_elements(jumptable));

        ZEND_HASH_FOREACH_VAL(jumptable, zv) {
          Z_LVAL_P(zv) = ZEND_OPLINE_TO_OFFSET(opline, new_opcodes + blocks[b->successors[s++]].start);
        } ZEND_HASH_FOREACH_END();
        opline->extended_value = ZEND_OPLINE_TO_OFFSET(opline, new_opcodes + blocks[b->successors[s++]].start);
        break;
      }
    }
  }

  /* adjust exception jump targets & remove unused try_catch_array entries */
  if (op_array->last_try_catch) {
    uint32_t i, j;
    uint32_t *map;
    ALLOCA_FLAG(use_heap);

    map = (uint32_t *)do_alloca(sizeof(uint32_t) * op_array->last_try_catch, use_heap);
    for (i = 0, j = 0; i< op_array->last_try_catch; i++) {
      if (blocks[cfg->map[op_array->try_catch_array[i].try_op]].flags & ZEND_BB_REACHABLE) {
        map[i] = j;
        op_array->try_catch_array[j].try_op = blocks[cfg->map[op_array->try_catch_array[i].try_op]].start;
        if (op_array->try_catch_array[i].catch_op) {
          op_array->try_catch_array[j].catch_op = blocks[cfg->map[op_array->try_catch_array[i].catch_op]].start;
        } else {
          op_array->try_catch_array[j].catch_op =  0;
        }
        if (op_array->try_catch_array[i].finally_op) {
          op_array->try_catch_array[j].finally_op = blocks[cfg->map[op_array->try_catch_array[i].finally_op]].start;
        } else {
          op_array->try_catch_array[j].finally_op =  0;
        }
        if (!op_array->try_catch_array[i].finally_end) {
          op_array->try_catch_array[j].finally_end = 0;
        } else {
          op_array->try_catch_array[j].finally_end = blocks[cfg->map[op_array->try_catch_array[i].finally_end]].start;
        }
        j++;
      }
    }
    if (i != j) {
      op_array->last_try_catch = j;
      if (j == 0) {
        efree(op_array->try_catch_array);
        op_array->try_catch_array = NULL;
      }

      if (op_array->fn_flags & ZEND_ACC_HAS_FINALLY_BLOCK) {
        zend_op *finally_opline = new_opcodes;
        const zend_op *last_finally_op = finally_opline + len;
        while (finally_opline < last_finally_op) {
          if (finally_opline->opcode == ZEND_FAST_RET &&
              finally_opline->op2.num != (uint32_t)-1 &&
              finally_opline->op2.num < j) {
            finally_opline->op2.num = map[finally_opline->op2.num];
          }
          finally_opline++;
        }
      }
    }
    free_alloca(map, use_heap);
  }

  /* rebuild map (just for printing) */
  memset(cfg->map, -1, sizeof(int) * op_array->last);
  for (uint32_t n = 0; n < cfg->blocks_count; n++) {
    if (cfg->blocks[n].flags & (ZEND_BB_REACHABLE|ZEND_BB_UNREACHABLE_FREE)) {
      cfg->map[cfg->blocks[n].start] = n;
    }
  }
}

static zend_always_inline zend_basic_block *get_target_block(const zend_cfg *cfg, const zend_basic_block *block, int n, uint32_t *opt_count)
{
  int b;
  zend_basic_block *target_block = cfg->blocks + block->successors[n];

  if (target_block->len == 0 && !(target_block->flags & ZEND_BB_PROTECTED)) {
    do {
      b = target_block->successors[0];
      target_block = cfg->blocks + b;
    } while (target_block->len == 0 && !(target_block->flags & ZEND_BB_PROTECTED));
    block->successors[n] = b;
    ++(*opt_count);
  }
  return target_block;
}

static zend_always_inline zend_basic_block *get_follow_block(const zend_cfg *cfg, const zend_basic_block *block, int n, uint32_t *opt_count)
{
  int b;
  zend_basic_block *target_block = cfg->blocks + block->successors[n];

  if (target_block->len == 0 && !(target_block->flags & ZEND_BB_PROTECTED)) {
    do {
      b = target_block->successors[0];
      target_block = cfg->blocks + b;
    } while (target_block->len == 0 && !(target_block->flags & ZEND_BB_PROTECTED));
    block->successors[n] = b;
    ++(*opt_count);
  }
  return target_block;
}

static zend_always_inline zend_basic_block *get_next_block(const zend_cfg *cfg, zend_basic_block *block)
{
  zend_basic_block *next_block = block + 1;
  const zend_basic_block *end = cfg->blocks + cfg->blocks_count;

  while (1) {
    if (next_block == end) {
      return NULL;
    } else if (next_block->flags & ZEND_BB_REACHABLE) {
      break;
    }
    next_block++;
  }
  while (next_block->len == 0 && !(next_block->flags & (ZEND_BB_TARGET|ZEND_BB_PROTECTED))) {
    next_block = cfg->blocks + next_block->successors[0];
  }
  return next_block;
}


/* we use "jmp_hitlist" to avoid infinity loops during jmp optimization */
static zend_always_inline bool in_hitlist(int target, const int *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; \
  }

static void zend_jmp_optimization(zend_basic_block *block, zend_op_array *op_array, const zend_cfg *cfg, int *jmp_hitlist, uint32_t *opt_count)
{
  /* last_op is the last opcode of the current block */
  zend_basic_block *target_block, *follow_block, *next_block;
  zend_op *last_op, *target;
  int next, jmp_hitlist_count;

  if (block->len == 0) {
    return;
  }

  last_op = op_array->opcodes + block->start + block->len - 1;
  switch (last_op->opcode) {
    case ZEND_JMP:
      jmp_hitlist_count = 0;

      target_block = get_target_block(cfg, block, 0, opt_count);
      while (target_block->len == 1) {
        target = op_array->opcodes + target_block->start;
        if (target->opcode == ZEND_JMP) {
          /* JMP L, L: JMP L1 -> JMP L1 */
          next = target_block->successors[0];
        } else {
          break;
        }
        CHECK_LOOP(next);
        block->successors[0] = next;
        ++(*opt_count);
        target_block = get_target_block(cfg, block, 0, opt_count);
      }

      next_block = get_next_block(cfg, block);
      if (target_block == next_block) {
        /* JMP(next) -> NOP */
        MAKE_NOP(last_op);
        ++(*opt_count);
        block->len--;
      } else if (target_block->len == 1) {
        target = op_array->opcodes + target_block->start;
        if ((target->opcode == ZEND_RETURN ||
                    target->opcode == ZEND_RETURN_BY_REF ||
                    target->opcode == ZEND_GENERATOR_RETURN) &&
                   !(op_array->fn_flags & ZEND_ACC_HAS_FINALLY_BLOCK)) {
          /* JMP L, L: RETURN to immediate RETURN */
          *last_op = *target;
          if (last_op->op1_type == IS_CONST) {
            zval zv;
            ZVAL_COPY(&zv, &ZEND_OP1_LITERAL(last_op));
            last_op->op1.constant = zend_optimizer_add_literal(op_array, &zv);
          }
          block->successors_count = 0;
          ++(*opt_count);
        }
      }
      break;

    case ZEND_JMP_SET:
    case ZEND_COALESCE:
    case ZEND_JMP_NULL:
      jmp_hitlist_count = 0;

      target_block = get_target_block(cfg, block, 0, opt_count);
      while (target_block->len == 1) {
        target = op_array->opcodes + target_block->start;

        if (target->opcode == ZEND_JMP) {
          /* JMP_SET(X, L), L: JMP(L2) -> JMP_SET(X, L2) */
          next = target_block->successors[0];
          CHECK_LOOP(next);
          block->successors[0] = next;
          ++(*opt_count);
        } else {
          break;
        }
        target_block = get_target_block(cfg, block, 0, opt_count);
      }
      break;

    case ZEND_JMPZ:
    case ZEND_JMPNZ:
      jmp_hitlist_count = 0;

      target_block = get_target_block(cfg, block, 0, opt_count);
      while (target_block->len == 1) {
        target = op_array->opcodes + target_block->start;

        if (target->opcode == ZEND_JMP) {
          /* JMPZ(X, L), L: JMP(L2) -> JMPZ(X, L2) */
          next = target_block->successors[0];
        } else if (target->opcode == last_op->opcode &&
                   SAME_VAR(target->op1, last_op->op1)) {
          /* JMPZ(X, L), L: JMPZ(X, L2) -> JMPZ(X, L2) */
          next = target_block->successors[0];
        } else if (target->opcode == INV_COND(last_op->opcode) &&
                   SAME_VAR(target->op1, last_op->op1)) {
          /* JMPZ(X, L), L: JMPNZ(X, L2) -> JMPZ(X, L+1) */
          next = target_block->successors[1];
        } else {
          break;
        }
        CHECK_LOOP(next);
        block->successors[0] = next;
        ++(*opt_count);
        target_block = get_target_block(cfg, block, 0, opt_count);
      }

      follow_block = get_follow_block(cfg, block, 1, opt_count);
      if (target_block == follow_block) {
        /* L: JMP[N]Z(X, L+1) -> NOP or FREE(X) */
        zend_optimizer_convert_to_free_op1(op_array, last_op);
        if (last_op->opcode == ZEND_NOP) {
          block->len--;
        }
        block->successors_count = 1;
        ++(*opt_count);
      } else if (follow_block->len == 1) {
        target = op_array->opcodes + follow_block->start;
        if (target->opcode == ZEND_JMP) {
            if (block->successors[0] == follow_block->successors[0]) {
            /* JMPZ(X,L1), JMP(L1) -> NOP, JMP(L1) */
            zend_optimizer_convert_to_free_op1(op_array, last_op);
            if (last_op->opcode == ZEND_NOP) {
              block->len--;
            }
            block->successors[0] = follow_block - cfg->blocks;
            block->successors_count = 1;
            ++(*opt_count);
            break;
          } else if (!(follow_block->flags & (ZEND_BB_TARGET | ZEND_BB_PROTECTED))) {
            next_block = get_next_block(cfg, follow_block);

            if (target_block == next_block) {
              /* JMPZ(X,L1) JMP(L2) L1: -> JMPNZ(X,L2) NOP*/

              last_op->opcode = INV_COND(last_op->opcode);

              block->successors[0] = follow_block->successors[0];
              block->successors[1] = next_block - cfg->blocks;

              follow_block->flags &= ~ZEND_BB_REACHABLE;
              MAKE_NOP(target);
              follow_block->len = 0;

              next_block->flags |= ZEND_BB_FOLLOW;

              break;
            }
          }
        }
      }
      break;

    case ZEND_JMPNZ_EX:
    case ZEND_JMPZ_EX:
      jmp_hitlist_count = 0;

      target_block = get_target_block(cfg, block, 0, opt_count);
      while (target_block->len == 1) {
        target = op_array->opcodes + target_block->start;

        if (target->opcode == ZEND_JMP) {
          /* T = JMPZ_EX(X, L), L: JMP(L2) -> T = JMPZ(X, L2) */
          next = target_block->successors[0];
        } else if (target->opcode == last_op->opcode-3 &&
                   (SAME_VAR(target->op1, last_op->result) ||
                    SAME_VAR(target->op1, last_op->op1))) {
          /* T = JMPZ_EX(X, L1), L1: JMPZ({X|T}, L2) -> T = JMPZ_EX(X, L2) */
          next = target_block->successors[0];
        } else if (target->opcode == last_op->opcode &&
                   target->result.var == last_op->result.var &&
                   (SAME_VAR(target->op1, last_op->result) ||
                    SAME_VAR(target->op1, last_op->op1))) {
          /* T = JMPZ_EX(X, L1), L1: T = JMPZ_EX({X|T}, L2) -> T = JMPZ_EX(X, L2) */
          next = target_block->successors[0];
        } else if (target->opcode == INV_EX_COND(last_op->opcode) &&
                   (SAME_VAR(target->op1, last_op->result) ||
                    SAME_VAR(target->op1, last_op->op1))) {
          /* T = JMPZ_EX(X, L1), L1: JMPNZ({X|T1}, L2) -> T = JMPZ_EX(X, L1+1) */
          next = target_block->successors[1];
        } else if (target->opcode == INV_EX_COND_EX(last_op->opcode) &&
                   target->result.var == last_op->result.var &&
                   (SAME_VAR(target->op1, last_op->result) ||
                    SAME_VAR(target->op1, last_op->op1))) {
          /* T = JMPZ_EX(X, L1), L1: T = JMPNZ_EX({X|T}, L2) -> T = JMPZ_EX(X, L1+1) */
          next = target_block->successors[1];
        } else if (target->opcode == ZEND_BOOL &&
                   (SAME_VAR(target->op1, last_op->result) ||
                    SAME_VAR(target->op1, last_op->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.                              */
          last_op->result.var = target->result.var;
          next = target_block->successors[0];
        } else {
          break;
        }
        CHECK_LOOP(next);
        block->successors[0] = next;
        ++(*opt_count);
        target_block = get_target_block(cfg, block, 0, opt_count);
      }

      follow_block = get_follow_block(cfg, block, 1, opt_count);
      if (target_block == follow_block) {
        /* L: T = JMP[N]Z_EX(X, L+1) -> T = BOOL(X) */
        last_op->opcode = ZEND_BOOL;
        last_op->op2.num = 0;
        block->successors_count = 1;
        ++(*opt_count);
        break;
      }
      break;
  }
}

/* Global data dependencies */

/* Find a set of variables which are used outside of the block where they are
 * defined. We won't apply some optimization patterns for such variables. */
static void zend_t_usage(const zend_cfg *cfg, const zend_op_array *op_array, zend_bitset used_ext, zend_optimizer_ctx *ctx)
{
  uint32_t n;
  zend_basic_block *block, *next_block;
  uint32_t var_num;
  uint32_t bitset_len;
  zend_bitset usage;
  zend_bitset defined_here;
  void *checkpoint;
  zend_op *opline, *end;


  if (op_array->T == 0) {
    /* shortcut - if no Ts, nothing to do */
    return;
  }

  checkpoint = zend_arena_checkpoint(ctx->arena);
  bitset_len = zend_bitset_len(op_array->last_var + op_array->T);
  defined_here = zend_arena_alloc(&ctx->arena, bitset_len * ZEND_BITSET_ELM_SIZE);

  zend_bitset_clear(defined_here, bitset_len);
  for (n = 1; n < cfg->blocks_count; n++) {
    block = cfg->blocks + n;

    if (!(block->flags & ZEND_BB_REACHABLE)) {
      continue;
    }

    opline = op_array->opcodes + block->start;
    end = opline + block->len;
    if (!(block->flags & ZEND_BB_FOLLOW) ||
        (block->flags & ZEND_BB_TARGET)) {
      /* Skip continuation of "extended" BB */
      zend_bitset_clear(defined_here, bitset_len);
    }

    while (opline<end) {
      if (opline->op1_type & (IS_VAR|IS_TMP_VAR)) {
        var_num = VAR_NUM(opline->op1.var);
        if (!zend_bitset_in(defined_here, var_num)) {
          zend_bitset_incl(used_ext, var_num);
        }
      }
      if (opline->op2_type == IS_VAR) {
        var_num = VAR_NUM(opline->op2.var);
        if (opline->opcode == ZEND_FE_FETCH_R ||
            opline->opcode == ZEND_FE_FETCH_RW) {
          /* these opcode use the op2 as result */
          zend_bitset_incl(defined_here, var_num);
        } else if (!zend_bitset_in(defined_here, var_num)) {
          zend_bitset_incl(used_ext, var_num);
        }
      } else if (opline->op2_type == IS_TMP_VAR) {
        var_num = VAR_NUM(opline->op2.var);
        if (!zend_bitset_in(defined_here, var_num)) {
          zend_bitset_incl(used_ext, var_num);
        }
      }

      if (opline->result_type == IS_VAR) {
        var_num = VAR_NUM(opline->result.var);
        zend_bitset_incl(defined_here, var_num);
      } else if (opline->result_type == IS_TMP_VAR) {
        var_num = VAR_NUM(opline->result.var);
        switch (opline->opcode) {
          case ZEND_ADD_ARRAY_ELEMENT:
          case ZEND_ADD_ARRAY_UNPACK:
          case ZEND_ROPE_ADD:
            /* these opcodes use the result as argument */
            if (!zend_bitset_in(defined_here, var_num)) {
              zend_bitset_incl(used_ext, var_num);
            }
            break;
          default :
            zend_bitset_incl(defined_here, var_num);
        }
      }
      opline++;
    }
  }

  if (ctx->debug_level & ZEND_DUMP_BLOCK_PASS_VARS) {
    bool printed = false;
    uint32_t i;

    for (i = op_array->last_var; i< op_array->T; i++) {
      if (zend_bitset_in(used_ext, i)) {
        if (!printed) {
          fprintf(stderr, "NON-LOCAL-VARS: %d", i);
          printed = true;
        } else {
          fprintf(stderr, ", %d", i);
        }
      }
    }
    if (printed) {
      fprintf(stderr, "\n");
    }
  }

  usage = defined_here;
  next_block = NULL;
  for (n = cfg->blocks_count; n > 0;) {
    block = cfg->blocks + (--n);

    if (!(block->flags & ZEND_BB_REACHABLE) || block->len == 0) {
      continue;
    }

    end = op_array->opcodes + block->start;
    opline = end + block->len - 1;
    if (!next_block ||
        !(next_block->flags & ZEND_BB_FOLLOW) ||
        (next_block->flags & ZEND_BB_TARGET)) {
      /* Skip continuation of "extended" BB */
      zend_bitset_copy(usage, used_ext, bitset_len);
    } else if (block->successors_count > 1) {
      zend_bitset_union(usage, used_ext, bitset_len);
    }
    next_block = block;

    while (opline >= end) {
      /* usage checks */
      if (opline->result_type & (IS_VAR|IS_TMP_VAR)) {
        if (!zend_bitset_in(usage, VAR_NUM(opline->result.var))) {
          switch (opline->opcode) {
            case ZEND_ASSIGN_OP:
            case ZEND_ASSIGN_DIM_OP:
            case ZEND_ASSIGN_OBJ_OP:
            case ZEND_ASSIGN_STATIC_PROP_OP:
            case ZEND_PRE_INC:
            case ZEND_PRE_DEC:
            case ZEND_ASSIGN:
            case ZEND_ASSIGN_REF:
            case ZEND_DO_FCALL:
            case ZEND_DO_ICALL:
            case ZEND_DO_UCALL:
            case ZEND_DO_FCALL_BY_NAME:
              opline->result_type = IS_UNUSED;
              break;
            case ZEND_POST_INC:
            case ZEND_POST_DEC:
            case ZEND_POST_INC_OBJ:
            case ZEND_POST_DEC_OBJ:
            case ZEND_POST_INC_STATIC_PROP:
            case ZEND_POST_DEC_STATIC_PROP:
              opline->opcode -= 2;
              opline->result_type = IS_UNUSED;
              break;
            case ZEND_QM_ASSIGN:
            case ZEND_BOOL:
            case ZEND_BOOL_NOT:
              zend_optimizer_convert_to_free_op1(op_array, opline);
              break;
            case ZEND_JMPZ_EX:
            case ZEND_JMPNZ_EX:
              opline->opcode -= 3;
              SET_UNUSED(opline->result);
              break;
            case ZEND_ADD_ARRAY_ELEMENT:
            case ZEND_ADD_ARRAY_UNPACK:
            case ZEND_ROPE_ADD:
              zend_bitset_incl(usage, VAR_NUM(opline->result.var));
              break;
          }
        } else {
          switch (opline->opcode) {
            case ZEND_ADD_ARRAY_ELEMENT:
            case ZEND_ADD_ARRAY_UNPACK:
            case ZEND_ROPE_ADD:
              break;
            default:
              zend_bitset_excl(usage, VAR_NUM(opline->result.var));
              break;
          }
        }
      }

      if (opline->op2_type == IS_VAR) {
        switch (opline->opcode) {
          case ZEND_FE_FETCH_R:
          case ZEND_FE_FETCH_RW:
            zend_bitset_excl(usage, VAR_NUM(opline->op2.var));
            break;
          default:
            zend_bitset_incl(usage, VAR_NUM(opline->op2.var));
            break;
        }
      } else if (opline->op2_type == IS_TMP_VAR) {
        zend_bitset_incl(usage, VAR_NUM(opline->op2.var));
      }

      if (opline->op1_type & (IS_VAR|IS_TMP_VAR)) {
        zend_bitset_incl(usage, VAR_NUM(opline->op1.var));
      }

      opline--;
    }
  }

  zend_arena_release(&ctx->arena, checkpoint);
}

static void zend_merge_blocks(const zend_op_array *op_array, const zend_cfg *cfg, uint32_t *opt_count)
{
  zend_basic_block *b, *bb;
  zend_basic_block *prev = NULL;

  for (uint32_t i = 0; i < cfg->blocks_count; i++) {
    b = cfg->blocks + i;
    if (b->flags & ZEND_BB_REACHABLE) {
      if ((b->flags & ZEND_BB_FOLLOW) &&
          !(b->flags & (ZEND_BB_TARGET | ZEND_BB_PROTECTED)) &&
          prev && prev->successors_count == 1 && prev->successors[0] == i)
      {
        zend_op *last_op = op_array->opcodes + prev->start + prev->len - 1;
        if (prev->len != 0 && last_op->opcode == ZEND_JMP) {
          MAKE_NOP(last_op);
        }

        for (bb = prev + 1; bb != b; bb++) {
          zend_op *op = op_array->opcodes + bb->start;
          const zend_op *end = op + bb->len;
          while (op < end) {
            if (op->op1_type == IS_CONST) {
              literal_dtor(&ZEND_OP1_LITERAL(op));
            }
            if (op->op2_type == IS_CONST) {
              literal_dtor(&ZEND_OP2_LITERAL(op));
            }
            MAKE_NOP(op);
            op++;
          }
          /* make block empty */
          bb->len = 0;
        }

        /* re-link */
        prev->flags |= (b->flags & ZEND_BB_EXIT);
        prev->len = b->start + b->len - prev->start;
        prev->successors_count = b->successors_count;
        if (b->successors != b->successors_storage) {
          prev->successors = b->successors;
          b->successors = b->successors_storage;
        } else {
          memcpy(prev->successors, b->successors, b->successors_count * sizeof(int));
        }

        /* unlink & make block empty and unreachable */
        b->flags = 0;
        b->len = 0;
        b->successors_count = 0;
        ++(*opt_count);
      } else {
        prev = b;
      }
    }
  }
}

#define PASSES 3

void zend_optimize_cfg(zend_op_array *op_array, zend_optimizer_ctx *ctx)
{
  zend_cfg cfg;
  zend_basic_block *blocks, *b;
  int pass;
  uint32_t bitset_len;
  zend_bitset usage;
  void *checkpoint;
  zend_op **Tsource;
  uint32_t opt_count;
  int *jmp_hitlist;

    /* Build CFG */
  checkpoint = zend_arena_checkpoint(ctx->arena);
  zend_build_cfg(&ctx->arena, op_array, 0, &cfg);

  if (cfg.blocks_count * (op_array->last_var + op_array->T) > 64 * 1024 * 1024) {
    zend_arena_release(&ctx->arena, checkpoint);
    return;
  }

  if (ctx->debug_level & ZEND_DUMP_BEFORE_BLOCK_PASS) {
    zend_dump_op_array(op_array, ZEND_DUMP_CFG, "before block pass", &cfg);
  }

  bitset_len = zend_bitset_len(op_array->last_var + op_array->T);
  Tsource = zend_arena_calloc(&ctx->arena, op_array->last_var + op_array->T, sizeof(zend_op *));
  usage = zend_arena_alloc(&ctx->arena, bitset_len * ZEND_BITSET_ELM_SIZE);
  jmp_hitlist = zend_arena_alloc(&ctx->arena, cfg.blocks_count * sizeof(int));

  blocks = cfg.blocks;
  const zend_basic_block *end = blocks + cfg.blocks_count;
  for (pass = 0; pass < PASSES; pass++) {
    opt_count = 0;

    /* Compute data dependencies */
    zend_bitset_clear(usage, bitset_len);
    zend_t_usage(&cfg, op_array, usage, ctx);

    /* optimize each basic block separately */
    for (b = blocks; b < end; b++) {
      if (!(b->flags & ZEND_BB_REACHABLE)) {
        continue;
      }
      /* we track data dependencies only inside a single basic block */
      if (!(b->flags & ZEND_BB_FOLLOW) ||
          (b->flags & ZEND_BB_TARGET)) {
        /* Skip continuation of "extended" BB */
        memset(Tsource, 0, (op_array->last_var + op_array->T) * sizeof(zend_op *));
      }
      zend_optimize_block(b, op_array, usage, &cfg, Tsource, &opt_count);
    }

    /* Eliminate NOPs */
    for (b = blocks; b < end; b++) {
      if (b->flags & ZEND_BB_UNREACHABLE_FREE) {
        /* In unreachable_free blocks only preserve loop var frees. */
        for (uint32_t i = b->start; i < b->start + b->len; i++) {
          zend_op *opline = &op_array->opcodes[i];
          if (!zend_optimizer_is_loop_var_free(opline)) {
            MAKE_NOP(opline);
          }
        }
      }
      if (b->flags & (ZEND_BB_REACHABLE|ZEND_BB_UNREACHABLE_FREE)) {
        strip_nops(op_array, b);
      }
    }

    opt_count = 0;

    /* Jump optimization for each block */
    for (b = blocks; b < end; b++) {
      if (b->flags & ZEND_BB_REACHABLE) {
        zend_jmp_optimization(b, op_array, &cfg, jmp_hitlist, &opt_count);
      }
    }

    /* Eliminate unreachable basic blocks */
    zend_cfg_remark_reachable_blocks(op_array, &cfg);

    /* Merge Blocks */
    zend_merge_blocks(op_array, &cfg, &opt_count);

    if (opt_count == 0) {
      break;
    }
  }

  assemble_code_blocks(&cfg, op_array, ctx);

  if (ctx->debug_level & ZEND_DUMP_AFTER_BLOCK_PASS) {
    zend_dump_op_array(op_array, ZEND_DUMP_CFG | ZEND_DUMP_HIDE_UNREACHABLE, "after block pass", &cfg);
  }

  /* Destroy CFG */
  zend_arena_release(&ctx->arena, checkpoint);
}

Coverage Report

Created: 2026-09-14 06:25