/src/php-src/Zend/Optimizer/dfa_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: 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_ssa.h"
#include "zend_func_info.h"
#include "zend_call_graph.h"
#include "zend_inference.h"
#include "zend_dump.h"

#ifndef ZEND_DEBUG_DFA
# define ZEND_DEBUG_DFA ZEND_DEBUG
#endif

#if ZEND_DEBUG_DFA
# include "ssa_integrity.c"
#endif

zend_result zend_dfa_analyze_op_array(zend_op_array *op_array, zend_optimizer_ctx *ctx, zend_ssa *ssa)
{
  uint32_t build_flags;

  if (op_array->last_try_catch) {
    /* TODO: we can't analyze functions with try/catch/finally ??? */
    return FAILURE;
  }

    /* Build SSA */
  memset(ssa, 0, sizeof(zend_ssa));

  zend_build_cfg(&ctx->arena, op_array, ZEND_CFG_NO_ENTRY_PREDECESSORS, &ssa->cfg);

  if ((ssa->cfg.flags & ZEND_FUNC_INDIRECT_VAR_ACCESS)) {
    /* TODO: we can't analyze functions with indirect variable access ??? */
    return FAILURE;
  }

  zend_cfg_build_predecessors(&ctx->arena, &ssa->cfg);

  if (ctx->debug_level & ZEND_DUMP_DFA_CFG) {
    zend_dump_op_array(op_array, ZEND_DUMP_CFG, "dfa cfg", &ssa->cfg);
  }

  /* Compute Dominators Tree */
  zend_cfg_compute_dominators_tree(op_array, &ssa->cfg);

  /* Identify reducible and irreducible loops */
  zend_cfg_identify_loops(op_array, &ssa->cfg);

  if (ctx->debug_level & ZEND_DUMP_DFA_DOMINATORS) {
    zend_dump_dominators(op_array, &ssa->cfg);
  }

  build_flags = 0;
  if (ctx->debug_level & ZEND_DUMP_DFA_LIVENESS) {
    build_flags |= ZEND_SSA_DEBUG_LIVENESS;
  }
  if (ctx->debug_level & ZEND_DUMP_DFA_PHI) {
    build_flags |= ZEND_SSA_DEBUG_PHI_PLACEMENT;
  }
  if (zend_build_ssa(&ctx->arena, ctx->script, op_array, build_flags, ssa) == FAILURE) {
    return FAILURE;
  }

  if (ctx->debug_level & ZEND_DUMP_DFA_SSA) {
    zend_dump_op_array(op_array, ZEND_DUMP_SSA, "dfa ssa", ssa);
  }


  zend_ssa_compute_use_def_chains(&ctx->arena, op_array, ssa);

  zend_ssa_find_false_dependencies(op_array, ssa);

  zend_ssa_find_sccs(op_array, ssa);

  if (zend_ssa_inference(&ctx->arena, op_array, ctx->script, ssa, ctx->optimization_level) == FAILURE) {
    return FAILURE;
  }

  if (zend_ssa_escape_analysis(ctx->script, op_array, ssa) == FAILURE) {
    return FAILURE;
  }

  if (ctx->debug_level & ZEND_DUMP_DFA_SSA_VARS) {
    zend_dump_ssa_variables(op_array, ssa, 0);
  }

  return SUCCESS;
}

static void zend_ssa_remove_nops(zend_op_array *op_array, zend_ssa *ssa, zend_optimizer_ctx *ctx)
{
  zend_basic_block *blocks = ssa->cfg.blocks;
  zend_basic_block *blocks_end = blocks + ssa->cfg.blocks_count;
  zend_basic_block *b;
  zend_func_info *func_info;
  int j;
  uint32_t i = 0;
  uint32_t target = 0;
  uint32_t *shiftlist;
  ALLOCA_FLAG(use_heap);

  shiftlist = (uint32_t *)do_alloca(sizeof(uint32_t) * op_array->last, use_heap);
  memset(shiftlist, 0, sizeof(uint32_t) * op_array->last);
  /* remove empty callee_info */
  func_info = ZEND_FUNC_INFO(op_array);
  if (func_info) {
    zend_call_info **call_info = &func_info->callee_info;
    while ((*call_info)) {
      if ((*call_info)->caller_init_opline->opcode == ZEND_NOP) {
        *call_info = (*call_info)->next_callee;
      } else {
        call_info = &(*call_info)->next_callee;
      }
    }
  }

  for (b = blocks; b < blocks_end; b++) {
    if (b->flags & (ZEND_BB_REACHABLE|ZEND_BB_UNREACHABLE_FREE)) {
      if (b->len) {
        uint32_t new_start, old_end;
        while (i < b->start) {
          shiftlist[i] = i - target;
          i++;
        }

        if (b->flags & ZEND_BB_UNREACHABLE_FREE) {
          /* Only keep the FREE for the loop var */
          ZEND_ASSERT(op_array->opcodes[b->start].opcode == ZEND_FREE
              || op_array->opcodes[b->start].opcode == ZEND_FE_FREE);
          b->len = 1;
        }

        new_start = target;
        old_end = b->start + b->len;
        while (i < old_end) {
          shiftlist[i] = i - target;
          if (EXPECTED(op_array->opcodes[i].opcode != ZEND_NOP)) {
            if (i != target) {
              op_array->opcodes[target] = op_array->opcodes[i];
              ssa->ops[target] = ssa->ops[i];
              ssa->cfg.map[target] = b - blocks;
            }
            target++;
          }
          i++;
        }
        b->start = new_start;
        if (target != old_end) {
          zend_op *opline;
          zend_op *new_opline;

          b->len = target - b->start;
          opline = op_array->opcodes + old_end - 1;
          if (opline->opcode == ZEND_NOP) {
            continue;
          }

          new_opline = op_array->opcodes + target - 1;
          zend_optimizer_migrate_jump(op_array, new_opline, opline);
        }
      } else {
        b->start = target;
      }
    } else {
      b->start = target;
      b->len = 0;
    }
  }

  if (target != op_array->last) {
    /* reset rest opcodes */
    for (i = target; i < op_array->last; i++) {
      MAKE_NOP(op_array->opcodes + i);
    }

    /* update SSA variables */
    for (j = 0; j < ssa->vars_count; j++) {
      if (ssa->vars[j].definition >= 0) {
        ssa->vars[j].definition -= shiftlist[ssa->vars[j].definition];
      }
      if (ssa->vars[j].use_chain >= 0) {
        ssa->vars[j].use_chain -= shiftlist[ssa->vars[j].use_chain];
      }
    }
    for (i = 0; i < op_array->last; i++) {
      if (ssa->ops[i].op1_use_chain >= 0) {
        ssa->ops[i].op1_use_chain -= shiftlist[ssa->ops[i].op1_use_chain];
      }
      if (ssa->ops[i].op2_use_chain >= 0) {
        ssa->ops[i].op2_use_chain -= shiftlist[ssa->ops[i].op2_use_chain];
      }
      if (ssa->ops[i].res_use_chain >= 0) {
        ssa->ops[i].res_use_chain -= shiftlist[ssa->ops[i].res_use_chain];
      }
    }

    /* update branch targets */
    for (b = blocks; b < blocks_end; b++) {
      if ((b->flags & ZEND_BB_REACHABLE) && b->len != 0) {
        zend_op *opline = op_array->opcodes + b->start + b->len - 1;
        zend_optimizer_shift_jump(op_array, opline, shiftlist);
      }
    }

    /* update try/catch array */
    for (uint32_t j = 0; j < op_array->last_try_catch; j++) {
      op_array->try_catch_array[j].try_op -= shiftlist[op_array->try_catch_array[j].try_op];
      op_array->try_catch_array[j].catch_op -= shiftlist[op_array->try_catch_array[j].catch_op];
      if (op_array->try_catch_array[j].finally_op) {
        op_array->try_catch_array[j].finally_op -= shiftlist[op_array->try_catch_array[j].finally_op];
        op_array->try_catch_array[j].finally_end -= shiftlist[op_array->try_catch_array[j].finally_end];
      }
    }

    /* update call graph */
    if (func_info) {
      zend_call_info *call_info = func_info->callee_info;
      while (call_info) {
        call_info->caller_init_opline -=
          shiftlist[call_info->caller_init_opline - op_array->opcodes];
        if (call_info->caller_call_opline) {
          call_info->caller_call_opline -=
            shiftlist[call_info->caller_call_opline - op_array->opcodes];
        }
        call_info = call_info->next_callee;
      }
    }

    op_array->last = target;
  }
  free_alloca(shiftlist, use_heap);
}

static bool safe_instanceof(const zend_class_entry *ce1, const zend_class_entry *ce2) {
  if (ce1 == ce2) {
    return true;
  }
  if (!(ce1->ce_flags & ZEND_ACC_LINKED)) {
    /* This case could be generalized, similarly to unlinked_instanceof */
    return false;
  }
  return instanceof_function(ce1, ce2);
}

static inline bool can_elide_list_type(
  const zend_script *script, const zend_op_array *op_array,
  const zend_ssa_var_info *use_info, const zend_type type)
{
  const zend_type *single_type;
  /* For intersection: result==false is failure, default is success.
   * For union: result==true is success, default is failure. */
  bool is_intersection = ZEND_TYPE_IS_INTERSECTION(type);
  ZEND_TYPE_FOREACH(type, single_type) {
    if (ZEND_TYPE_HAS_LIST(*single_type)) {
      ZEND_ASSERT(!is_intersection);
      return can_elide_list_type(script, op_array, use_info, *single_type);
    }
    if (ZEND_TYPE_HAS_NAME(*single_type)) {
      zend_string *lcname = zend_string_tolower(ZEND_TYPE_NAME(*single_type));
      const zend_class_entry *ce = zend_optimizer_get_class_entry(script, op_array, lcname);
      zend_string_release(lcname);
      bool result = ce && safe_instanceof(use_info->ce, ce);
      if (result == !is_intersection) {
        return result;
      }
    }
  } ZEND_TYPE_FOREACH_END();
  return is_intersection;
}

static inline bool can_elide_return_type_check(
    const zend_script *script, zend_op_array *op_array, zend_ssa *ssa, zend_ssa_op *ssa_op) {
  zend_arg_info *arg_info = &op_array->arg_info[-1];
  zend_ssa_var_info *use_info = &ssa->var_info[ssa_op->op1_use];
  uint32_t use_type = use_info->type & (MAY_BE_ANY|MAY_BE_UNDEF);
  if (use_type & MAY_BE_REF) {
    return false;
  }

  if (use_type & MAY_BE_UNDEF) {
    use_type &= ~MAY_BE_UNDEF;
    use_type |= MAY_BE_NULL;
  }

  uint32_t disallowed_types = use_type & ~ZEND_TYPE_PURE_MASK(arg_info->type);
  if (!disallowed_types) {
    /* Only contains allowed types. */
    return true;
  }

  if (disallowed_types == MAY_BE_OBJECT && use_info->ce && ZEND_TYPE_IS_COMPLEX(arg_info->type)) {
    return can_elide_list_type(script, op_array, use_info, arg_info->type);
  }

  return false;
}

static bool opline_supports_assign_contraction(
    zend_op_array *op_array, zend_ssa *ssa, zend_op *opline, int src_var, uint32_t cv_var) {
  if (opline->opcode == ZEND_NEW) {
    /* see Zend/tests/generators/aborted_yield_during_new.phpt */
    return false;
  }

  /* Frameless calls override the return value, but the return value may overlap with the arguments. */
  switch (opline->opcode) {
    case ZEND_FRAMELESS_ICALL_3:
      if ((opline + 1)->op1_type == IS_CV && (opline + 1)->op1.var == cv_var) return false;
      ZEND_FALLTHROUGH;
    case ZEND_FRAMELESS_ICALL_2:
      if (opline->op2_type == IS_CV && opline->op2.var == cv_var) return false;
      ZEND_FALLTHROUGH;
    case ZEND_FRAMELESS_ICALL_1:
      if (opline->op1_type == IS_CV && opline->op1.var == cv_var) return false;
      return true;
  }

  if (opline->opcode == ZEND_DO_ICALL || opline->opcode == ZEND_DO_UCALL
      || opline->opcode == ZEND_DO_FCALL || opline->opcode == ZEND_DO_FCALL_BY_NAME) {
    /* Function calls may dtor the return value after it has already been written -- allow
     * direct assignment only for types where a double-dtor does not matter. */
    uint32_t type = ssa->var_info[src_var].type;
    uint32_t simple = MAY_BE_NULL|MAY_BE_FALSE|MAY_BE_TRUE|MAY_BE_LONG|MAY_BE_DOUBLE;
    return !((type & MAY_BE_ANY) & ~simple);
  }

  if (opline->opcode == ZEND_POST_INC || opline->opcode == ZEND_POST_DEC) {
    /* POST_INC/DEC write the result variable before performing the inc/dec. For $i = $i++
     * eliding the temporary variable would thus yield an incorrect result. */
    return opline->op1_type != IS_CV || opline->op1.var != cv_var;
  }

  if (opline->opcode == ZEND_INIT_ARRAY) {
    /* INIT_ARRAY initializes the result array before reading key/value. */
    return (opline->op1_type != IS_CV || opline->op1.var != cv_var)
      && (opline->op2_type != IS_CV || opline->op2.var != cv_var);
  }

  if (opline->opcode == ZEND_CAST
      && (opline->extended_value == IS_ARRAY || opline->extended_value == IS_OBJECT)) {
    /* CAST to array/object may initialize the result to an empty array/object before
     * reading the expression. */
    return opline->op1_type != IS_CV || opline->op1.var != cv_var;
  }

  if ((opline->opcode == ZEND_ASSIGN_OP
    || opline->opcode == ZEND_ASSIGN_OBJ
    || opline->opcode == ZEND_ASSIGN_DIM
    || opline->opcode == ZEND_ASSIGN_OBJ_OP
    || opline->opcode == ZEND_ASSIGN_DIM_OP)
   && opline->op1_type == IS_CV
   && opline->op1.var == cv_var
   && zend_may_throw(opline, &ssa->ops[ssa->vars[src_var].definition], op_array, ssa)) {
    return false;
  }

  return true;
}

static bool variable_defined_or_used_in_range(zend_ssa *ssa, int var, int start, int end)
{
  while (start < end) {
    const zend_ssa_op *ssa_op = &ssa->ops[start];
    if ((ssa_op->op1_def >= 0 && ssa->vars[ssa_op->op1_def].var == var) ||
      (ssa_op->op2_def >= 0 && ssa->vars[ssa_op->op2_def].var == var) ||
      (ssa_op->result_def >= 0 && ssa->vars[ssa_op->result_def].var == var) ||
      (ssa_op->op1_use >= 0 && ssa->vars[ssa_op->op1_use].var == var) ||
      (ssa_op->op2_use >= 0 && ssa->vars[ssa_op->op2_use].var == var) ||
      (ssa_op->result_use >= 0 && ssa->vars[ssa_op->result_use].var == var)
    ) {
      return true;
    }
    start++;
  }
  return false;
}

static uint32_t zend_dfa_optimize_calls(zend_op_array *op_array, zend_ssa *ssa)
{
  const zend_func_info *func_info = ZEND_FUNC_INFO(op_array);
  uint32_t removed_ops = 0;

  if (func_info->callee_info) {
    const zend_call_info *call_info = func_info->callee_info;

    do {
      zend_op *op = call_info->caller_init_opline;

      if ((op->opcode == ZEND_FRAMELESS_ICALL_2
        || (op->opcode == ZEND_FRAMELESS_ICALL_3 && (op + 1)->op1_type == IS_CONST))
       && call_info->callee_func
       && zend_string_equals_literal_ci(call_info->callee_func->common.function_name, "in_array")) {
        bool strict = false;
        bool has_opdata = op->opcode == ZEND_FRAMELESS_ICALL_3;
        ZEND_ASSERT(!call_info->is_prototype);

        if (has_opdata) {
          if (zend_is_true(CT_CONSTANT_EX(op_array, (op + 1)->op1.constant))) {
            strict = true;
          }
        }

        if (op->op2_type == IS_CONST
         && Z_TYPE_P(CT_CONSTANT_EX(op_array, op->op2.constant)) == IS_ARRAY) {
          bool ok = true;

          const HashTable *src = Z_ARRVAL_P(CT_CONSTANT_EX(op_array, op->op2.constant));
          HashTable *dst;
          zval *val, tmp;
          zend_ulong idx;

          ZVAL_TRUE(&tmp);
          dst = zend_new_array(zend_hash_num_elements(src));
          if (strict) {
            ZEND_HASH_FOREACH_VAL(src, val) {
              if (Z_TYPE_P(val) == IS_STRING) {
                zend_hash_add(dst, Z_STR_P(val), &tmp);
              } else if (Z_TYPE_P(val) == IS_LONG) {
                zend_hash_index_add(dst, Z_LVAL_P(val), &tmp);
              } else {
                zend_array_destroy(dst);
                ok = false;
                break;
              }
            } ZEND_HASH_FOREACH_END();
          } else {
            ZEND_HASH_FOREACH_VAL(src, val) {
              if (Z_TYPE_P(val) != IS_STRING || ZEND_HANDLE_NUMERIC(Z_STR_P(val), idx)) {
                zend_array_destroy(dst);
                ok = false;
                break;
              }
              zend_hash_add(dst, Z_STR_P(val), &tmp);
            } ZEND_HASH_FOREACH_END();
          }

          if (ok) {
            ZVAL_ARR(&tmp, dst);

            /* Update opcode */
            op->opcode = ZEND_IN_ARRAY;
            op->extended_value = strict;
            op->op2.constant = zend_optimizer_add_literal(op_array, &tmp);
            if (has_opdata) {
              MAKE_NOP(op + 1);
              removed_ops++;
            }
          }
        }
      }
      call_info = call_info->next_callee;
    } while (call_info);
  }

  return removed_ops;
}

static zend_always_inline void take_successor_0(zend_ssa *ssa, uint32_t block_num, zend_basic_block *block)
{
  if (block->successors_count == 2) {
    if (block->successors[1] != block->successors[0]) {
      zend_ssa_remove_predecessor(ssa, block_num, block->successors[1]);
    }
    block->successors_count = 1;
  }
}

static zend_always_inline void take_successor_1(zend_ssa *ssa, uint32_t block_num, zend_basic_block *block)
{
  if (block->successors_count == 2) {
    if (block->successors[1] != block->successors[0]) {
      zend_ssa_remove_predecessor(ssa, block_num, block->successors[0]);
      block->successors[0] = block->successors[1];
    }
    block->successors_count = 1;
  }
}

static zend_always_inline void take_successor_ex(zend_ssa *ssa, uint32_t block_num, zend_basic_block *block, int target_block)
{
  for (uint32_t i = 0; i < block->successors_count; i++) {
    if (block->successors[i] != target_block) {
      zend_ssa_remove_predecessor(ssa, block_num, block->successors[i]);
    }
  }
  block->successors[0] = target_block;
  block->successors_count = 1;
}

static void compress_block(zend_op_array *op_array, zend_basic_block *block)
{
  while (block->len > 0) {
    zend_op *opline = &op_array->opcodes[block->start + block->len - 1];

    if (opline->opcode == ZEND_NOP) {
      block->len--;
    } else {
      break;
    }
  }
}

static void replace_predecessor(zend_ssa *ssa, int block_id, int old_pred, int new_pred) {
  zend_basic_block *block = &ssa->cfg.blocks[block_id];
  int *predecessors = &ssa->cfg.predecessors[block->predecessor_offset];
  zend_ssa_phi *phi;

  int old_pred_idx = -1;
  int new_pred_idx = -1;
  for (uint32_t i = 0; i < block->predecessors_count; i++) {
    if (predecessors[i] == old_pred) {
      old_pred_idx = i;
    }
    if (predecessors[i] == new_pred) {
      new_pred_idx = i;
    }
  }

  ZEND_ASSERT(old_pred_idx != -1);
  if (new_pred_idx == -1) {
    /* If the new predecessor doesn't exist yet, simply rewire the old one */
    predecessors[old_pred_idx] = new_pred;
  } else {
    /* Otherwise, rewiring the old predecessor would make the new predecessor appear
     * twice, which violates our CFG invariants. Remove the old predecessor instead. */
    memmove(
      predecessors + old_pred_idx,
      predecessors + old_pred_idx + 1,
      sizeof(int) * (block->predecessors_count - old_pred_idx - 1)
    );

    /* Also remove the corresponding phi node entries */
    for (phi = ssa->blocks[block_id].phis; phi; phi = phi->next) {
      if (phi->pi >= 0) {
        if (phi->pi == old_pred || phi->pi == new_pred) {
          zend_ssa_rename_var_uses(
            ssa, phi->ssa_var, phi->sources[0], /* update_types */ 0);
          zend_ssa_remove_phi(ssa, phi);
        }
      } else {
        memmove(
          phi->sources + old_pred_idx,
          phi->sources + old_pred_idx + 1,
          sizeof(int) * (block->predecessors_count - old_pred_idx - 1)
        );
      }
    }

    block->predecessors_count--;
  }
}

static void zend_ssa_replace_control_link(zend_op_array *op_array, zend_ssa *ssa, int from, int to, int new_to)
{
  zend_basic_block *src = &ssa->cfg.blocks[from];
  zend_basic_block *old = &ssa->cfg.blocks[to];
  zend_basic_block *dst = &ssa->cfg.blocks[new_to];
  zend_op *opline;

  for (uint32_t i = 0; i < src->successors_count; i++) {
    if (src->successors[i] == to) {
      src->successors[i] = new_to;
    }
  }

  if (src->len > 0) {
    opline = op_array->opcodes + src->start + src->len - 1;
    switch (opline->opcode) {
      case ZEND_JMP:
      case ZEND_FAST_CALL:
        ZEND_ASSERT(ZEND_OP1_JMP_ADDR(opline) == op_array->opcodes + old->start);
        ZEND_SET_OP_JMP_ADDR(opline, opline->op1, op_array->opcodes + dst->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:
        if (ZEND_OP2_JMP_ADDR(opline) == op_array->opcodes + old->start) {
          ZEND_SET_OP_JMP_ADDR(opline, opline->op2, op_array->opcodes + dst->start);
        }
        break;
      case ZEND_CATCH:
        if (!(opline->extended_value & ZEND_LAST_CATCH)) {
          if (ZEND_OP2_JMP_ADDR(opline) == op_array->opcodes + old->start) {
            ZEND_SET_OP_JMP_ADDR(opline, opline->op2, op_array->opcodes + dst->start);
          }
        }
        break;
      case ZEND_FE_FETCH_R:
      case ZEND_FE_FETCH_RW:
        if (ZEND_OFFSET_TO_OPLINE_NUM(op_array, opline, opline->extended_value) == old->start) {
          opline->extended_value = ZEND_OPLINE_NUM_TO_OFFSET(op_array, opline, dst->start);
        }
        break;
      case ZEND_SWITCH_LONG:
      case ZEND_SWITCH_STRING:
      case ZEND_MATCH:
        {
          HashTable *jumptable = Z_ARRVAL(ZEND_OP2_LITERAL(opline));
          zval *zv;
          ZEND_HASH_FOREACH_VAL(jumptable, zv) {
            if (ZEND_OFFSET_TO_OPLINE_NUM(op_array, opline, Z_LVAL_P(zv)) == old->start) {
              Z_LVAL_P(zv) = ZEND_OPLINE_NUM_TO_OFFSET(op_array, opline, dst->start);
            }
          } ZEND_HASH_FOREACH_END();
          if (ZEND_OFFSET_TO_OPLINE_NUM(op_array, opline, opline->extended_value) == old->start) {
            opline->extended_value = ZEND_OPLINE_NUM_TO_OFFSET(op_array, opline, dst->start);
          }
          break;
        }
    }
  }

  replace_predecessor(ssa, new_to, to, from);
}

static void zend_ssa_unlink_block(zend_op_array *op_array, zend_ssa *ssa, zend_basic_block *block, uint32_t block_num)
{
  if (block->predecessors_count == 1 && ssa->blocks[block_num].phis == NULL) {
    int *predecessors;
    zend_basic_block *fe_fetch_block = NULL;

    ZEND_ASSERT(block->successors_count == 1);
    predecessors = &ssa->cfg.predecessors[block->predecessor_offset];
    if (block->predecessors_count == 1 && (block->flags & ZEND_BB_FOLLOW)) {
      zend_basic_block *pred_block = &ssa->cfg.blocks[predecessors[0]];

      if (pred_block->len > 0 && (pred_block->flags & ZEND_BB_REACHABLE)) {
        if ((op_array->opcodes[pred_block->start + pred_block->len - 1].opcode == ZEND_FE_FETCH_R
         || op_array->opcodes[pred_block->start + pred_block->len - 1].opcode == ZEND_FE_FETCH_RW)
          && op_array->opcodes[pred_block->start + pred_block->len - 1].op2_type == IS_CV) {
          fe_fetch_block = pred_block;
          }
      }
    }
    for (uint32_t i = 0; i < block->predecessors_count; i++) {
      zend_ssa_replace_control_link(op_array, ssa, predecessors[i], block_num, block->successors[0]);
    }
    zend_ssa_remove_block(op_array, ssa, block_num);
    if (fe_fetch_block && fe_fetch_block->successors[0] == fe_fetch_block->successors[1]) {
      /* The body of "foreach" loop was removed */
      int ssa_var = ssa->ops[fe_fetch_block->start + fe_fetch_block->len - 1].op2_def;
      if (ssa_var >= 0) {
        zend_ssa_remove_uses_of_var(ssa, ssa_var);
      }
    }
  }
}

static int zend_dfa_optimize_jmps(zend_op_array *op_array, zend_ssa *ssa)
{
  int removed_ops = 0;
  uint32_t block_num = 0;

  for (block_num = 1; block_num < ssa->cfg.blocks_count; block_num++) {
    zend_basic_block *block = &ssa->cfg.blocks[block_num];

    if (!(block->flags & ZEND_BB_REACHABLE)) {
      continue;
    }
    compress_block(op_array, block);
    if (block->len == 0) {
      zend_ssa_unlink_block(op_array, ssa, block, block_num);
    }
  }

  block_num = 0;
  while (block_num < ssa->cfg.blocks_count
    && !(ssa->cfg.blocks[block_num].flags & ZEND_BB_REACHABLE)) {
    block_num++;
  }
  while (block_num < ssa->cfg.blocks_count) {
    uint32_t next_block_num = block_num + 1;
    zend_basic_block *block = &ssa->cfg.blocks[block_num];
    uint32_t op_num;
    zend_op *opline;
    zend_ssa_op *ssa_op;
    bool can_follow = true;

    while (next_block_num < ssa->cfg.blocks_count
      && !(ssa->cfg.blocks[next_block_num].flags & ZEND_BB_REACHABLE)) {
      if (ssa->cfg.blocks[next_block_num].flags & ZEND_BB_UNREACHABLE_FREE) {
        can_follow = false;
      }
      next_block_num++;
    }

    if (block->len) {
      op_num = block->start + block->len - 1;
      opline = op_array->opcodes + op_num;
      ssa_op = ssa->ops + op_num;

      switch (opline->opcode) {
        case ZEND_JMP:
optimize_jmp:
          if (block->successors[0] == next_block_num && can_follow) {
            MAKE_NOP(opline);
            removed_ops++;
            goto optimize_nop;
          }
          break;
        case ZEND_JMPZ:
optimize_jmpz:
          if (opline->op1_type == IS_CONST) {
            if (zend_is_true(CT_CONSTANT_EX(op_array, opline->op1.constant))) {
              MAKE_NOP(opline);
              removed_ops++;
              take_successor_1(ssa, block_num, block);
              goto optimize_nop;
            } else {
              opline->opcode = ZEND_JMP;
              COPY_NODE(opline->op1, opline->op2);
              take_successor_0(ssa, block_num, block);
              goto optimize_jmp;
            }
          } else {
            if (block->successors[0] == next_block_num && can_follow) {
              take_successor_0(ssa, block_num, block);
              if (opline->op1_type == IS_CV && (OP1_INFO() & MAY_BE_UNDEF)) {
                opline->opcode = ZEND_CHECK_VAR;
                opline->op2.num = 0;
              } else if (opline->op1_type == IS_CV || !(OP1_INFO() & (MAY_BE_STRING|MAY_BE_ARRAY|MAY_BE_OBJECT|MAY_BE_RESOURCE|MAY_BE_REF))) {
                zend_ssa_remove_instr(ssa, opline, ssa_op);
                removed_ops++;
                goto optimize_nop;
              } else {
                opline->opcode = ZEND_FREE;
                opline->op2.num = 0;
              }
            }
          }
          break;
        case ZEND_JMPNZ:
optimize_jmpnz:
          if (opline->op1_type == IS_CONST) {
            if (zend_is_true(CT_CONSTANT_EX(op_array, opline->op1.constant))) {
              opline->opcode = ZEND_JMP;
              COPY_NODE(opline->op1, opline->op2);
              take_successor_0(ssa, block_num, block);
              goto optimize_jmp;
            } else {
              MAKE_NOP(opline);
              removed_ops++;
              take_successor_1(ssa, block_num, block);
              goto optimize_nop;
            }
          } else if (block->successors_count == 2) {
            if (block->successors[0] == next_block_num && can_follow) {
              take_successor_0(ssa, block_num, block);
              if (opline->op1_type == IS_CV && (OP1_INFO() & MAY_BE_UNDEF)) {
                opline->opcode = ZEND_CHECK_VAR;
                opline->op2.num = 0;
              } else if (opline->op1_type == IS_CV || !(OP1_INFO() & (MAY_BE_STRING|MAY_BE_ARRAY|MAY_BE_OBJECT|MAY_BE_RESOURCE|MAY_BE_REF))) {
                zend_ssa_remove_instr(ssa, opline, ssa_op);
                removed_ops++;
                goto optimize_nop;
              } else {
                opline->opcode = ZEND_FREE;
                opline->op2.num = 0;
              }
            }
          }
          break;
        case ZEND_JMPZ_EX:
          if (ssa->vars[ssa_op->result_def].use_chain < 0
              && ssa->vars[ssa_op->result_def].phi_use_chain == NULL) {
            opline->opcode = ZEND_JMPZ;
            opline->result_type = IS_UNUSED;
            zend_ssa_remove_result_def(ssa, ssa_op);
            goto optimize_jmpz;
          } else if (opline->op1_type == IS_CONST) {
            if (zend_is_true(CT_CONSTANT_EX(op_array, opline->op1.constant))) {
              opline->opcode = ZEND_BOOL;
              take_successor_1(ssa, block_num, block);
            }
          }
          break;
        case ZEND_JMPNZ_EX:
          if (ssa->vars[ssa_op->result_def].use_chain < 0
              && ssa->vars[ssa_op->result_def].phi_use_chain == NULL) {
            opline->opcode = ZEND_JMPNZ;
            opline->result_type = IS_UNUSED;
            zend_ssa_remove_result_def(ssa, ssa_op);
            goto optimize_jmpnz;
          } else if (opline->op1_type == IS_CONST) {
            if (!zend_is_true(CT_CONSTANT_EX(op_array, opline->op1.constant))) {
              opline->opcode = ZEND_BOOL;
              take_successor_1(ssa, block_num, block);
            }
          }
          break;
        case ZEND_JMP_SET:
          if (ssa->vars[ssa_op->result_def].use_chain < 0
              && ssa->vars[ssa_op->result_def].phi_use_chain == NULL) {
            opline->opcode = ZEND_JMPNZ;
            opline->result_type = IS_UNUSED;
            zend_ssa_remove_result_def(ssa, ssa_op);
            goto optimize_jmpnz;
          } else if (opline->op1_type == IS_CONST) {
            if (!zend_is_true(CT_CONSTANT_EX(op_array, opline->op1.constant))) {
              MAKE_NOP(opline);
              removed_ops++;
              take_successor_1(ssa, block_num, block);
              zend_ssa_remove_result_def(ssa, ssa_op);
              goto optimize_nop;
            }
          }
          break;
        case ZEND_COALESCE:
        {
          zend_ssa_var *var = &ssa->vars[ssa_op->result_def];
          if (opline->op1_type == IS_CONST
              && var->use_chain < 0 && var->phi_use_chain == NULL) {
            if (Z_TYPE_P(CT_CONSTANT_EX(op_array, opline->op1.constant)) == IS_NULL) {
              zend_ssa_remove_result_def(ssa, ssa_op);
              MAKE_NOP(opline);
              removed_ops++;
              take_successor_1(ssa, block_num, block);
              goto optimize_nop;
            } else {
              opline->opcode = ZEND_JMP;
              opline->result_type = IS_UNUSED;
              zend_ssa_remove_result_def(ssa, ssa_op);
              COPY_NODE(opline->op1, opline->op2);
              take_successor_0(ssa, block_num, block);
              goto optimize_jmp;
            }
          }
          break;
        }
        case ZEND_JMP_NULL:
        {
          zend_ssa_var *var = &ssa->vars[ssa_op->result_def];
          if (opline->op1_type == IS_CONST
              && var->use_chain < 0 && var->phi_use_chain == NULL) {
            if (Z_TYPE_P(CT_CONSTANT_EX(op_array, opline->op1.constant)) == IS_NULL) {
              opline->opcode = ZEND_JMP;
              opline->result_type = IS_UNUSED;
              zend_ssa_remove_result_def(ssa, ssa_op);
              COPY_NODE(opline->op1, opline->op2);
              take_successor_0(ssa, block_num, block);
              goto optimize_jmp;
            } else {
              zend_ssa_remove_result_def(ssa, ssa_op);
              MAKE_NOP(opline);
              removed_ops++;
              take_successor_1(ssa, block_num, block);
              goto optimize_nop;
            }
          }
          break;
        }
        case ZEND_SWITCH_LONG:
        case ZEND_SWITCH_STRING:
        case ZEND_MATCH:
          if (opline->op1_type == IS_CONST) {
            zval *zv = CT_CONSTANT_EX(op_array, opline->op1.constant);
            uint8_t type = Z_TYPE_P(zv);
            bool correct_type =
              (opline->opcode == ZEND_SWITCH_LONG && type == IS_LONG)
              || (opline->opcode == ZEND_SWITCH_STRING && type == IS_STRING)
              || (opline->opcode == ZEND_MATCH && (type == IS_LONG || type == IS_STRING));

            /* Switch statements have a fallback chain for loose comparison. In those
             * cases the SWITCH_* instruction is a NOP. Match does strict comparison and
             * thus jumps to the default branch on mismatched types, so we need to
             * convert MATCH to a jmp. */
            if (!correct_type && opline->opcode != ZEND_MATCH) {
              removed_ops++;
              MAKE_NOP(opline);
              opline->extended_value = 0;
              take_successor_ex(ssa, block_num, block, block->successors[block->successors_count - 1]);
              goto optimize_nop;
            }

            uint32_t target;
            if (correct_type) {
              HashTable *jmptable = Z_ARRVAL_P(CT_CONSTANT_EX(op_array, opline->op2.constant));
              zval *jmp_zv = type == IS_LONG
                ? zend_hash_index_find(jmptable, Z_LVAL_P(zv))
                : zend_hash_find(jmptable, Z_STR_P(zv));

              if (jmp_zv) {
                target = ZEND_OFFSET_TO_OPLINE_NUM(op_array, opline, Z_LVAL_P(jmp_zv));
              } else {
                target = ZEND_OFFSET_TO_OPLINE_NUM(op_array, opline, opline->extended_value);
              }
            } else {
              ZEND_ASSERT(opline->opcode == ZEND_MATCH);
              target = ZEND_OFFSET_TO_OPLINE_NUM(op_array, opline, opline->extended_value);
            }
            opline->opcode = ZEND_JMP;
            opline->extended_value = 0;
            SET_UNUSED(opline->op1);
            ZEND_SET_OP_JMP_ADDR(opline, opline->op1, op_array->opcodes + target);
            SET_UNUSED(opline->op2);
            take_successor_ex(ssa, block_num, block, ssa->cfg.map[target]);
            goto optimize_jmp;
          }
          break;
        case ZEND_NOP:
optimize_nop:
          compress_block(op_array, block);
          if (block->len == 0) {
            if (block_num > 0) {
              zend_ssa_unlink_block(op_array, ssa, block, block_num);
              /* backtrack to previous basic block */
              int backtracking_block_num = block_num;
              do {
                backtracking_block_num--;
              } while (backtracking_block_num >= 0
                && !(ssa->cfg.blocks[backtracking_block_num].flags & ZEND_BB_REACHABLE));
              if (backtracking_block_num >= 0) {
                block_num = backtracking_block_num;
                continue;
              }
            }
          }
          break;
        default:
          break;
      }
    }

    block_num = next_block_num;
  }

  return removed_ops;
}

static bool zend_dfa_try_to_replace_result(zend_op_array *op_array, zend_ssa *ssa, int def, int cv_var)
{
  int result_var = ssa->ops[def].result_def;
  uint32_t cv = EX_NUM_TO_VAR(ssa->vars[cv_var].var);

  if (result_var >= 0
   && !(ssa->var_info[cv_var].type & MAY_BE_REF)
   && ssa->vars[cv_var].alias == NO_ALIAS
   && ssa->vars[result_var].phi_use_chain == NULL
   && ssa->vars[result_var].sym_use_chain == NULL) {
    int use = ssa->vars[result_var].use_chain;

    if (use >= 0
     && zend_ssa_next_use(ssa->ops, result_var, use) < 0
     && op_array->opcodes[use].opcode != ZEND_FREE
     && op_array->opcodes[use].opcode != ZEND_SEND_VAL
     && op_array->opcodes[use].opcode != ZEND_SEND_VAL_EX
     && op_array->opcodes[use].opcode != ZEND_VERIFY_RETURN_TYPE
     && op_array->opcodes[use].opcode != ZEND_YIELD) {
      if (use > def) {
        int i = use;
        const zend_op *opline = &op_array->opcodes[use];

        while (i > def) {
          if ((opline->op1_type == IS_CV && opline->op1.var == cv)
           || (opline->op2_type == IS_CV && opline->op2.var == cv)
           || (opline->result_type == IS_CV && opline->result.var == cv)) {
            return false;
          }
          opline--;
          i--;
        }

        /* Update opcodes and reconstruct SSA */
        ssa->vars[result_var].definition = -1;
        ssa->vars[result_var].use_chain = -1;
        ssa->ops[def].result_def = -1;

        op_array->opcodes[def].result_type = IS_UNUSED;
        op_array->opcodes[def].result.var = 0;

        if (ssa->ops[use].op1_use == result_var) {
          ssa->ops[use].op1_use = cv_var;
          ssa->ops[use].op1_use_chain = ssa->vars[cv_var].use_chain;
          ssa->vars[cv_var].use_chain = use;

          op_array->opcodes[use].op1_type = IS_CV;
          op_array->opcodes[use].op1.var = cv;
        } else if (ssa->ops[use].op2_use == result_var) {
          ssa->ops[use].op2_use = cv_var;
          ssa->ops[use].op2_use_chain = ssa->vars[cv_var].use_chain;
          ssa->vars[cv_var].use_chain = use;

          op_array->opcodes[use].op2_type = IS_CV;
          op_array->opcodes[use].op2.var = cv;
        } else if (ssa->ops[use].result_use == result_var) {
          ssa->ops[use].result_use = cv_var;
          ssa->ops[use].res_use_chain = ssa->vars[cv_var].use_chain;
          ssa->vars[cv_var].use_chain = use;

          op_array->opcodes[use].result_type = IS_CV;
          op_array->opcodes[use].result.var = cv;
        }

        return true;
      }
    }
  }

  return false;
}

void zend_dfa_optimize_op_array(zend_op_array *op_array, zend_optimizer_ctx *ctx, zend_ssa *ssa, zend_call_info **call_map)
{
  if (ctx->debug_level & ZEND_DUMP_BEFORE_DFA_PASS) {
    zend_dump_op_array(op_array, ZEND_DUMP_SSA, "before dfa pass", ssa);
  }

  if (ssa->var_info) {
    int op_1;
    int v;
    int remove_nops = 0;
    zend_op *opline;
    zend_ssa_op *ssa_op;
    zval tmp;

#if ZEND_DEBUG_DFA
    ssa_verify_integrity(op_array, ssa, "before dfa");
#endif

    if (ZEND_OPTIMIZER_PASS_8 & ctx->optimization_level) {
      if (sccp_optimize_op_array(ctx, op_array, ssa, call_map)) {
        remove_nops = 1;
      }

      if (zend_dfa_optimize_jmps(op_array, ssa)) {
        remove_nops = 1;
      }

#if ZEND_DEBUG_DFA
      ssa_verify_integrity(op_array, ssa, "after sccp");
#endif
      if (ZEND_FUNC_INFO(op_array)) {
        if (zend_dfa_optimize_calls(op_array, ssa)) {
          remove_nops = 1;
        }
      }
      if (ctx->debug_level & ZEND_DUMP_AFTER_PASS_8) {
        zend_dump_op_array(op_array, ZEND_DUMP_SSA, "after sccp pass", ssa);
      }
#if ZEND_DEBUG_DFA
      ssa_verify_integrity(op_array, ssa, "after calls");
#endif
    }

    if (ZEND_OPTIMIZER_PASS_14 & ctx->optimization_level) {
      if (dce_optimize_op_array(op_array, ctx, ssa, 0)) {
        remove_nops = 1;
      }
      if (zend_dfa_optimize_jmps(op_array, ssa)) {
        remove_nops = 1;
      }
      if (ctx->debug_level & ZEND_DUMP_AFTER_PASS_14) {
        zend_dump_op_array(op_array, ZEND_DUMP_SSA, "after dce pass", ssa);
      }
#if ZEND_DEBUG_DFA
      ssa_verify_integrity(op_array, ssa, "after dce");
#endif
    }

    for (v = op_array->last_var; v < ssa->vars_count; v++) {

      op_1 = ssa->vars[v].definition;

      if (op_1 < 0) {
        continue;
      }

      opline = op_array->opcodes + op_1;
      ssa_op = &ssa->ops[op_1];

      /* Convert LONG constants to DOUBLE */
      if (ssa->var_info[v].use_as_double) {
        if (opline->opcode == ZEND_ASSIGN
         && opline->op2_type == IS_CONST
         && ssa->ops[op_1].op1_def == v
         && !RETURN_VALUE_USED(opline)
        ) {

// op_1: ASSIGN ? -> #v [use_as_double], long(?) => ASSIGN ? -> #v, double(?)

          zval *zv = CT_CONSTANT_EX(op_array, opline->op2.constant);
          ZEND_ASSERT(Z_TYPE_INFO_P(zv) == IS_LONG);
          ZVAL_DOUBLE(&tmp, zval_get_double(zv));
          opline->op2.constant = zend_optimizer_add_literal(op_array, &tmp);

        } else if (opline->opcode == ZEND_QM_ASSIGN
         && opline->op1_type == IS_CONST
        ) {

// op_1: QM_ASSIGN #v [use_as_double], long(?) => QM_ASSIGN #v, double(?)

          zval *zv = CT_CONSTANT_EX(op_array, opline->op1.constant);
          ZEND_ASSERT(Z_TYPE_INFO_P(zv) == IS_LONG);
          ZVAL_DOUBLE(&tmp, zval_get_double(zv));
          opline->op1.constant = zend_optimizer_add_literal(op_array, &tmp);
        }

      } else {
        if (opline->opcode == ZEND_ADD
         || opline->opcode == ZEND_SUB
         || opline->opcode == ZEND_MUL
         || opline->opcode == ZEND_IS_EQUAL
         || opline->opcode == ZEND_IS_NOT_EQUAL
         || opline->opcode == ZEND_IS_SMALLER
         || opline->opcode == ZEND_IS_SMALLER_OR_EQUAL
        ) {

          if (opline->op1_type == IS_CONST && opline->op2_type != IS_CONST) {
            zval *zv = CT_CONSTANT_EX(op_array, opline->op1.constant);

            if ((OP2_INFO() & MAY_BE_ANY) == MAY_BE_DOUBLE
             && Z_TYPE_INFO_P(zv) == IS_LONG) {

// op_1: #v.? = ADD long(?), #?.? [double] => #v.? = ADD double(?), #?.? [double]

              ZVAL_DOUBLE(&tmp, zval_get_double(zv));
              opline->op1.constant = zend_optimizer_add_literal(op_array, &tmp);
              zv = CT_CONSTANT_EX(op_array, opline->op1.constant);
            }
            if (opline->opcode == ZEND_ADD) {
              zv = CT_CONSTANT_EX(op_array, opline->op1.constant);

              if (((OP2_INFO() & (MAY_BE_ANY|MAY_BE_UNDEF)) == MAY_BE_LONG
                && Z_TYPE_INFO_P(zv) == IS_LONG
                && Z_LVAL_P(zv) == 0)
               || ((OP2_INFO() & (MAY_BE_ANY|MAY_BE_UNDEF)) == MAY_BE_DOUBLE
                && Z_TYPE_INFO_P(zv) == IS_DOUBLE
                && Z_DVAL_P(zv) == 0.0)) {

// op_1: #v.? = ADD 0, #?.? [double,long] => #v.? = QM_ASSIGN #?.?

                opline->opcode = ZEND_QM_ASSIGN;
                opline->op1_type = opline->op2_type;
                opline->op1.var = opline->op2.var;
                opline->op2_type = IS_UNUSED;
                opline->op2.num = 0;
                ssa->ops[op_1].op1_use = ssa->ops[op_1].op2_use;
                ssa->ops[op_1].op1_use_chain = ssa->ops[op_1].op2_use_chain;
                ssa->ops[op_1].op2_use = -1;
                ssa->ops[op_1].op2_use_chain = -1;
              }
            } else if (opline->opcode == ZEND_MUL
             && (OP2_INFO() & ((MAY_BE_ANY|MAY_BE_UNDEF)-(MAY_BE_LONG|MAY_BE_DOUBLE))) == 0) {
              zv = CT_CONSTANT_EX(op_array, opline->op1.constant);

              if ((Z_TYPE_INFO_P(zv) == IS_LONG
                && Z_LVAL_P(zv) == 2)
               || (Z_TYPE_INFO_P(zv) == IS_DOUBLE
                && Z_DVAL_P(zv) == 2.0
                && !(OP2_INFO() & MAY_BE_LONG))) {

// op_1: #v.? = MUL 2, #x.? [double,long] => #v.? = ADD #x.?, #x.?

                opline->opcode = ZEND_ADD;
                opline->op1_type = opline->op2_type;
                opline->op1.var = opline->op2.var;
                ssa->ops[op_1].op1_use = ssa->ops[op_1].op2_use;
                ssa->ops[op_1].op1_use_chain = ssa->ops[op_1].op2_use_chain;
              }
            }
          } else if (opline->op1_type != IS_CONST && opline->op2_type == IS_CONST) {
            zval *zv = CT_CONSTANT_EX(op_array, opline->op2.constant);

            if ((OP1_INFO() & MAY_BE_ANY) == MAY_BE_DOUBLE
             && Z_TYPE_INFO_P(CT_CONSTANT_EX(op_array, opline->op2.constant)) == IS_LONG) {

// op_1: #v.? = ADD #?.? [double], long(?) => #v.? = ADD #?.? [double], double(?)

              ZVAL_DOUBLE(&tmp, zval_get_double(zv));
              opline->op2.constant = zend_optimizer_add_literal(op_array, &tmp);
              zv = CT_CONSTANT_EX(op_array, opline->op2.constant);
            }
            if (opline->opcode == ZEND_ADD || opline->opcode == ZEND_SUB) {
              if (((OP1_INFO() & (MAY_BE_ANY|MAY_BE_UNDEF)) == MAY_BE_LONG
                && Z_TYPE_INFO_P(zv) == IS_LONG
                && Z_LVAL_P(zv) == 0)
               || ((OP1_INFO() & (MAY_BE_ANY|MAY_BE_UNDEF)) == MAY_BE_DOUBLE
                && Z_TYPE_INFO_P(zv) == IS_DOUBLE
                && Z_DVAL_P(zv) == 0.0)) {

// op_1: #v.? = ADD #?.? [double,long], 0 => #v.? = QM_ASSIGN #?.?

                opline->opcode = ZEND_QM_ASSIGN;
                opline->op2_type = IS_UNUSED;
                opline->op2.num = 0;
              }
            } else if (opline->opcode == ZEND_MUL
             && (OP1_INFO() & ((MAY_BE_ANY|MAY_BE_UNDEF)-(MAY_BE_LONG|MAY_BE_DOUBLE))) == 0) {
              zv = CT_CONSTANT_EX(op_array, opline->op2.constant);

              if ((Z_TYPE_INFO_P(zv) == IS_LONG
                && Z_LVAL_P(zv) == 2)
               || (Z_TYPE_INFO_P(zv) == IS_DOUBLE
                && Z_DVAL_P(zv) == 2.0
                && !(OP1_INFO() & MAY_BE_LONG))) {

// op_1: #v.? = MUL #x.? [double,long], 2 => #v.? = ADD #x.?, #x.?

                opline->opcode = ZEND_ADD;
                opline->op2_type = opline->op1_type;
                opline->op2.var = opline->op1.var;
                ssa->ops[op_1].op2_use = ssa->ops[op_1].op1_use;
                ssa->ops[op_1].op2_use_chain = ssa->ops[op_1].op1_use_chain;
              }
            }
          }
        } else if (opline->opcode == ZEND_CONCAT) {
          if (!(OP1_INFO() & MAY_BE_OBJECT)
           && !(OP2_INFO() & MAY_BE_OBJECT)) {
            opline->opcode = ZEND_FAST_CONCAT;
          }
        } else if (opline->opcode == ZEND_VERIFY_RETURN_TYPE
         && opline->op1_type != IS_CONST
         && ssa->ops[op_1].op1_def == v
         && ssa->ops[op_1].op1_use >= 0) {
          int orig_var = ssa->ops[op_1].op1_use;
          int ret = ssa->vars[v].use_chain;

          if (ssa->ops[op_1].op1_use_chain == -1
           && can_elide_return_type_check(ctx->script, op_array, ssa, &ssa->ops[op_1])) {

// op_1: VERIFY_RETURN_TYPE #orig_var.? [T] -> #v.? [T] => NOP

            zend_ssa_unlink_use_chain(ssa, op_1, orig_var);

            if (ret >= 0) {
              ssa->ops[ret].op1_use = orig_var;
              ssa->ops[ret].op1_use_chain = ssa->vars[orig_var].use_chain;
              ssa->vars[orig_var].use_chain = ret;
            }

            ssa->vars[v].definition = -1;
            ssa->vars[v].use_chain = -1;

            ssa->ops[op_1].op1_def = -1;
            ssa->ops[op_1].op1_use = -1;

            MAKE_NOP(opline);
            remove_nops = 1;
          } else if (ret >= 0
           && ssa->ops[ret].op1_use == v
           && ssa->ops[ret].op1_use_chain == -1
           && can_elide_return_type_check(ctx->script, op_array, ssa, &ssa->ops[op_1])) {

// op_1: VERIFY_RETURN_TYPE #orig_var.? [T] -> #v.? [T] => NOP

            zend_ssa_replace_use_chain(ssa, op_1, ret, orig_var);

            ssa->ops[ret].op1_use = orig_var;
            ssa->ops[ret].op1_use_chain = ssa->ops[op_1].op1_use_chain;

            ssa->vars[v].definition = -1;
            ssa->vars[v].use_chain = -1;

            ssa->ops[op_1].op1_def = -1;
            ssa->ops[op_1].op1_use = -1;

            MAKE_NOP(opline);
            remove_nops = 1;
          }
        }
      }

      if (opline->opcode == ZEND_QM_ASSIGN
       && ssa->ops[op_1].result_def == v
       && opline->op1_type & (IS_TMP_VAR|IS_VAR)
       && !(ssa->var_info[v].type & (MAY_BE_STRING|MAY_BE_ARRAY|MAY_BE_OBJECT|MAY_BE_RESOURCE|MAY_BE_REF))
      ) {

        int src_var = ssa->ops[op_1].op1_use;

        if (src_var >= 0
         && !(ssa->var_info[src_var].type & MAY_BE_REF)
         && (ssa->var_info[src_var].type & (MAY_BE_UNDEF|MAY_BE_ANY))
         && ssa->vars[src_var].definition >= 0
         && ssa->ops[ssa->vars[src_var].definition].result_def == src_var
         && ssa->ops[ssa->vars[src_var].definition].result_use < 0
         && ssa->vars[src_var].use_chain == op_1
         && ssa->ops[op_1].op1_use_chain < 0
         && !ssa->vars[src_var].phi_use_chain
         && !ssa->vars[src_var].sym_use_chain
         && opline_supports_assign_contraction(
           op_array, ssa, &op_array->opcodes[ssa->vars[src_var].definition],
           src_var, opline->result.var)
         && !variable_defined_or_used_in_range(ssa, EX_VAR_TO_NUM(opline->result.var),
            ssa->vars[src_var].definition+1, op_1)
        ) {

          int orig_var = ssa->ops[op_1].result_use;
          int op_2 = ssa->vars[src_var].definition;

// op_2: #src_var.T = OP ...                                        => #v.CV = OP ...
// op_1: QM_ASSIGN #src_var.T #orig_var.CV [undef,scalar] -> #v.CV,    NOP

          if (orig_var >= 0) {
            zend_ssa_unlink_use_chain(ssa, op_1, orig_var);
          }

          /* Reconstruct SSA */
          ssa->vars[v].definition = op_2;
          ssa->ops[op_2].result_def = v;

          ssa->vars[src_var].definition = -1;
          ssa->vars[src_var].use_chain = -1;

          ssa->ops[op_1].op1_use = -1;
          ssa->ops[op_1].op1_def = -1;
          ssa->ops[op_1].op1_use_chain = -1;
          ssa->ops[op_1].result_use = -1;
          ssa->ops[op_1].result_def = -1;
          ssa->ops[op_1].res_use_chain = -1;

          /* Update opcodes */
          op_array->opcodes[op_2].result_type = opline->result_type;
          op_array->opcodes[op_2].result.var = opline->result.var;

          MAKE_NOP(opline);
          remove_nops = 1;

          if (op_array->opcodes[op_2].opcode == ZEND_SUB
           && op_array->opcodes[op_2].op1_type == op_array->opcodes[op_2].result_type
           && op_array->opcodes[op_2].op1.var == op_array->opcodes[op_2].result.var
           && op_array->opcodes[op_2].op2_type == IS_CONST
           && Z_TYPE_P(CT_CONSTANT_EX(op_array, op_array->opcodes[op_2].op2.constant)) == IS_LONG
           && Z_LVAL_P(CT_CONSTANT_EX(op_array, op_array->opcodes[op_2].op2.constant)) == 1
           && ssa->ops[op_2].op1_use >= 0
           && !(ssa->var_info[ssa->ops[op_2].op1_use].type & (MAY_BE_FALSE|MAY_BE_TRUE|MAY_BE_STRING|MAY_BE_ARRAY|MAY_BE_OBJECT|MAY_BE_RESOURCE|MAY_BE_REF))) {

            op_array->opcodes[op_2].opcode = ZEND_PRE_DEC;
            SET_UNUSED(op_array->opcodes[op_2].op2);
            SET_UNUSED(op_array->opcodes[op_2].result);

            ssa->ops[op_2].result_def = -1;
            ssa->ops[op_2].op1_def = v;

          } else if (op_array->opcodes[op_2].opcode == ZEND_ADD
           && op_array->opcodes[op_2].op1_type == op_array->opcodes[op_2].result_type
           && op_array->opcodes[op_2].op1.var == op_array->opcodes[op_2].result.var
           && op_array->opcodes[op_2].op2_type == IS_CONST
           && Z_TYPE_P(CT_CONSTANT_EX(op_array, op_array->opcodes[op_2].op2.constant)) == IS_LONG
           && Z_LVAL_P(CT_CONSTANT_EX(op_array, op_array->opcodes[op_2].op2.constant)) == 1
           && ssa->ops[op_2].op1_use >= 0
           && !(ssa->var_info[ssa->ops[op_2].op1_use].type & (MAY_BE_FALSE|MAY_BE_TRUE|MAY_BE_STRING|MAY_BE_ARRAY|MAY_BE_OBJECT|MAY_BE_RESOURCE|MAY_BE_REF))) {

            op_array->opcodes[op_2].opcode = ZEND_PRE_INC;
            SET_UNUSED(op_array->opcodes[op_2].op2);
            SET_UNUSED(op_array->opcodes[op_2].result);

            ssa->ops[op_2].result_def = -1;
            ssa->ops[op_2].op1_def = v;

          } else if (op_array->opcodes[op_2].opcode == ZEND_ADD
           && op_array->opcodes[op_2].op2_type == op_array->opcodes[op_2].result_type
           && op_array->opcodes[op_2].op2.var == op_array->opcodes[op_2].result.var
           && op_array->opcodes[op_2].op1_type == IS_CONST
           && Z_TYPE_P(CT_CONSTANT_EX(op_array, op_array->opcodes[op_2].op1.constant)) == IS_LONG
           && Z_LVAL_P(CT_CONSTANT_EX(op_array, op_array->opcodes[op_2].op1.constant)) == 1
           && ssa->ops[op_2].op2_use >= 0
           && !(ssa->var_info[ssa->ops[op_2].op2_use].type & (MAY_BE_FALSE|MAY_BE_TRUE|MAY_BE_STRING|MAY_BE_ARRAY|MAY_BE_OBJECT|MAY_BE_RESOURCE|MAY_BE_REF))) {

            op_array->opcodes[op_2].opcode = ZEND_PRE_INC;
            op_array->opcodes[op_2].op1_type = op_array->opcodes[op_2].op2_type;
            op_array->opcodes[op_2].op1.var = op_array->opcodes[op_2].op2.var;
            SET_UNUSED(op_array->opcodes[op_2].op2);
            SET_UNUSED(op_array->opcodes[op_2].result);

            ssa->ops[op_2].result_def = -1;
            ssa->ops[op_2].op1_def = v;
            ssa->ops[op_2].op1_use = ssa->ops[op_2].op2_use;
            ssa->ops[op_2].op1_use_chain = ssa->ops[op_2].op2_use_chain;
            ssa->ops[op_2].op2_use = -1;
            ssa->ops[op_2].op2_use_chain = -1;
          }
        }
      }

      if (ssa->vars[v].var >= op_array->last_var) {
        /* skip TMP and VAR */
        continue;
      }

      if (ssa->ops[op_1].op1_def == v
       && RETURN_VALUE_USED(opline)) {
        if (opline->opcode == ZEND_ASSIGN
         || opline->opcode == ZEND_ASSIGN_OP
         || opline->opcode == ZEND_PRE_INC
         || opline->opcode == ZEND_PRE_DEC) {
          zend_dfa_try_to_replace_result(op_array, ssa, op_1, v);
        } else if (opline->opcode == ZEND_POST_INC) {
          int result_var = ssa->ops[op_1].result_def;

          if (result_var >= 0
           && (ssa->var_info[result_var].type & ((MAY_BE_ANY|MAY_BE_REF|MAY_BE_UNDEF) - (MAY_BE_LONG|MAY_BE_DOUBLE))) == 0) {
            int use = ssa->vars[result_var].use_chain;

            if (use >= 0 && op_array->opcodes[use].opcode == ZEND_IS_SMALLER
             && ssa->ops[use].op1_use == result_var
             && zend_dfa_try_to_replace_result(op_array, ssa, op_1, v)) {
              opline->opcode = ZEND_PRE_INC;
              op_array->opcodes[use].opcode = ZEND_IS_SMALLER_OR_EQUAL;
            }
          }
        } else if (opline->opcode == ZEND_POST_DEC) {
          int result_var = ssa->ops[op_1].result_def;

          if (result_var >= 0
           && (ssa->var_info[result_var].type & ((MAY_BE_ANY|MAY_BE_REF|MAY_BE_UNDEF) - (MAY_BE_LONG|MAY_BE_DOUBLE))) == 0) {
            int use = ssa->vars[result_var].use_chain;

            if (use >= 0 && op_array->opcodes[use].opcode == ZEND_IS_SMALLER
             && ssa->ops[use].op2_use == result_var
             && zend_dfa_try_to_replace_result(op_array, ssa, op_1, v)) {
              opline->opcode = ZEND_PRE_DEC;
              op_array->opcodes[use].opcode = ZEND_IS_SMALLER_OR_EQUAL;
            }
          }
        }
      }

      if (opline->opcode == ZEND_ASSIGN
       && ssa->ops[op_1].op1_def == v
       && !RETURN_VALUE_USED(opline)
      ) {
        int orig_var = ssa->ops[op_1].op1_use;

        if (orig_var >= 0
         && !(ssa->var_info[orig_var].type & (MAY_BE_STRING|MAY_BE_ARRAY|MAY_BE_OBJECT|MAY_BE_RESOURCE|MAY_BE_REF))
        ) {
          int src_var = ssa->ops[op_1].op2_use;

          if ((opline->op2_type & (IS_TMP_VAR|IS_VAR))
           && src_var >= 0
           && !(ssa->var_info[src_var].type & MAY_BE_REF)
           && (ssa->var_info[src_var].type & (MAY_BE_UNDEF|MAY_BE_ANY))
           && ssa->vars[src_var].definition >= 0
           && ssa->ops[ssa->vars[src_var].definition].result_def == src_var
           && ssa->ops[ssa->vars[src_var].definition].result_use < 0
           && ssa->vars[src_var].use_chain == op_1
           && ssa->ops[op_1].op2_use_chain < 0
           && !ssa->vars[src_var].phi_use_chain
           && !ssa->vars[src_var].sym_use_chain
           && opline_supports_assign_contraction(
             op_array, ssa, &op_array->opcodes[ssa->vars[src_var].definition],
             src_var, opline->op1.var)
           && !variable_defined_or_used_in_range(ssa, EX_VAR_TO_NUM(opline->op1.var),
              ssa->vars[src_var].definition+1, op_1)
          ) {

            int op_2 = ssa->vars[src_var].definition;

// op_2: #src_var.T = OP ...                                     => #v.CV = OP ...
// op_1: ASSIGN #orig_var.CV [undef,scalar] -> #v.CV, #src_var.T    NOP

            zend_ssa_unlink_use_chain(ssa, op_1, orig_var);
            /* Reconstruct SSA */
            ssa->vars[v].definition = op_2;
            ssa->ops[op_2].result_def = v;

            ssa->vars[src_var].definition = -1;
            ssa->vars[src_var].use_chain = -1;

            ssa->ops[op_1].op1_use = -1;
            ssa->ops[op_1].op2_use = -1;
            ssa->ops[op_1].op1_def = -1;
            ssa->ops[op_1].op1_use_chain = -1;

            /* Update opcodes */
            op_array->opcodes[op_2].result_type = opline->op1_type;
            op_array->opcodes[op_2].result.var = opline->op1.var;

            MAKE_NOP(opline);
            remove_nops = 1;

            if (op_array->opcodes[op_2].opcode == ZEND_SUB
             && op_array->opcodes[op_2].op1_type == op_array->opcodes[op_2].result_type
             && op_array->opcodes[op_2].op1.var == op_array->opcodes[op_2].result.var
             && op_array->opcodes[op_2].op2_type == IS_CONST
             && Z_TYPE_P(CT_CONSTANT_EX(op_array, op_array->opcodes[op_2].op2.constant)) == IS_LONG
             && Z_LVAL_P(CT_CONSTANT_EX(op_array, op_array->opcodes[op_2].op2.constant)) == 1
             && ssa->ops[op_2].op1_use >= 0
             && !(ssa->var_info[ssa->ops[op_2].op1_use].type & (MAY_BE_FALSE|MAY_BE_TRUE|MAY_BE_STRING|MAY_BE_ARRAY|MAY_BE_OBJECT|MAY_BE_RESOURCE|MAY_BE_REF))) {

              op_array->opcodes[op_2].opcode = ZEND_PRE_DEC;
              SET_UNUSED(op_array->opcodes[op_2].op2);
              SET_UNUSED(op_array->opcodes[op_2].result);

              ssa->ops[op_2].result_def = -1;
              ssa->ops[op_2].op1_def = v;

            } else if (op_array->opcodes[op_2].opcode == ZEND_ADD
             && op_array->opcodes[op_2].op1_type == op_array->opcodes[op_2].result_type
             && op_array->opcodes[op_2].op1.var == op_array->opcodes[op_2].result.var
             && op_array->opcodes[op_2].op2_type == IS_CONST
             && Z_TYPE_P(CT_CONSTANT_EX(op_array, op_array->opcodes[op_2].op2.constant)) == IS_LONG
             && Z_LVAL_P(CT_CONSTANT_EX(op_array, op_array->opcodes[op_2].op2.constant)) == 1
             && ssa->ops[op_2].op1_use >= 0
             && !(ssa->var_info[ssa->ops[op_2].op1_use].type & (MAY_BE_FALSE|MAY_BE_TRUE|MAY_BE_STRING|MAY_BE_ARRAY|MAY_BE_OBJECT|MAY_BE_RESOURCE|MAY_BE_REF))) {

              op_array->opcodes[op_2].opcode = ZEND_PRE_INC;
              SET_UNUSED(op_array->opcodes[op_2].op2);
              SET_UNUSED(op_array->opcodes[op_2].result);

              ssa->ops[op_2].result_def = -1;
              ssa->ops[op_2].op1_def = v;

            } else if (op_array->opcodes[op_2].opcode == ZEND_ADD
             && op_array->opcodes[op_2].op2_type == op_array->opcodes[op_2].result_type
             && op_array->opcodes[op_2].op2.var == op_array->opcodes[op_2].result.var
             && op_array->opcodes[op_2].op1_type == IS_CONST
             && Z_TYPE_P(CT_CONSTANT_EX(op_array, op_array->opcodes[op_2].op1.constant)) == IS_LONG
             && Z_LVAL_P(CT_CONSTANT_EX(op_array, op_array->opcodes[op_2].op1.constant)) == 1
             && ssa->ops[op_2].op2_use >= 0
             && !(ssa->var_info[ssa->ops[op_2].op2_use].type & (MAY_BE_FALSE|MAY_BE_TRUE|MAY_BE_STRING|MAY_BE_ARRAY|MAY_BE_OBJECT|MAY_BE_RESOURCE|MAY_BE_REF))) {

              op_array->opcodes[op_2].opcode = ZEND_PRE_INC;
              op_array->opcodes[op_2].op1_type = op_array->opcodes[op_2].op2_type;
              op_array->opcodes[op_2].op1.var = op_array->opcodes[op_2].op2.var;
              SET_UNUSED(op_array->opcodes[op_2].op2);
              SET_UNUSED(op_array->opcodes[op_2].result);

              ssa->ops[op_2].result_def = -1;
              ssa->ops[op_2].op1_def = v;
              ssa->ops[op_2].op1_use = ssa->ops[op_2].op2_use;
              ssa->ops[op_2].op1_use_chain = ssa->ops[op_2].op2_use_chain;
              ssa->ops[op_2].op2_use = -1;
              ssa->ops[op_2].op2_use_chain = -1;
            }
          } else if (opline->op2_type == IS_CONST
           || ((opline->op2_type & (IS_TMP_VAR|IS_VAR|IS_CV))
               && ssa->ops[op_1].op2_use >= 0
               && ssa->ops[op_1].op2_def < 0)
          ) {

// op_1: ASSIGN #orig_var.CV [undef,scalar] -> #v.CV, CONST|TMPVAR => QM_ASSIGN v.CV, CONST|TMPVAR

            if (ssa->ops[op_1].op1_use != ssa->ops[op_1].op2_use) {
              zend_ssa_unlink_use_chain(ssa, op_1, orig_var);
            } else {
              ssa->ops[op_1].op2_use_chain = ssa->ops[op_1].op1_use_chain;
            }

            /* Reconstruct SSA */
            ssa->ops[op_1].result_def = v;
            ssa->ops[op_1].op1_def = -1;
            ssa->ops[op_1].op1_use = ssa->ops[op_1].op2_use;
            ssa->ops[op_1].op1_use_chain = ssa->ops[op_1].op2_use_chain;
            ssa->ops[op_1].op2_use = -1;
            ssa->ops[op_1].op2_use_chain = -1;

            /* Update opcode */
            opline->result_type = opline->op1_type;
            opline->result.var = opline->op1.var;
            opline->op1_type = opline->op2_type;
            opline->op1.var = opline->op2.var;
            opline->op2_type = IS_UNUSED;
            opline->op2.var = 0;
            opline->opcode = ZEND_QM_ASSIGN;
          }
        }

      } else if (opline->opcode == ZEND_ASSIGN_OP
       && opline->extended_value == ZEND_ADD
       && ssa->ops[op_1].op1_def == v
       && opline->op2_type == IS_CONST
       && Z_TYPE_P(CT_CONSTANT_EX(op_array, opline->op2.constant)) == IS_LONG
       && Z_LVAL_P(CT_CONSTANT_EX(op_array, opline->op2.constant)) == 1
       && ssa->ops[op_1].op1_use >= 0
       && !(ssa->var_info[ssa->ops[op_1].op1_use].type & (MAY_BE_FALSE|MAY_BE_TRUE|MAY_BE_STRING|MAY_BE_ARRAY|MAY_BE_OBJECT|MAY_BE_RESOURCE|MAY_BE_REF))) {

// op_1: ASSIGN_ADD #?.CV [undef,null,int,foat] ->#v.CV, int(1) => PRE_INC #?.CV ->#v.CV

        opline->opcode = ZEND_PRE_INC;
        opline->extended_value = 0;
        SET_UNUSED(opline->op2);

      } else if (opline->opcode == ZEND_ASSIGN_OP
       && opline->extended_value == ZEND_SUB
       && ssa->ops[op_1].op1_def == v
       && opline->op2_type == IS_CONST
       && Z_TYPE_P(CT_CONSTANT_EX(op_array, opline->op2.constant)) == IS_LONG
       && Z_LVAL_P(CT_CONSTANT_EX(op_array, opline->op2.constant)) == 1
       && ssa->ops[op_1].op1_use >= 0
       && !(ssa->var_info[ssa->ops[op_1].op1_use].type & (MAY_BE_UNDEF|MAY_BE_NULL|MAY_BE_FALSE|MAY_BE_TRUE|MAY_BE_STRING|MAY_BE_ARRAY|MAY_BE_OBJECT|MAY_BE_RESOURCE|MAY_BE_REF))) {

// op_1: ASSIGN_SUB #?.CV [undef,null,int,foat] -> #v.CV, int(1) => PRE_DEC #?.CV ->#v.CV

        opline->opcode = ZEND_PRE_DEC;
        opline->extended_value = 0;
        SET_UNUSED(opline->op2);

      } else if (ssa->ops[op_1].op1_def == v
       && !RETURN_VALUE_USED(opline)
       && ssa->ops[op_1].op1_use >= 0
       && !(ssa->var_info[ssa->ops[op_1].op1_use].type & (MAY_BE_STRING|MAY_BE_ARRAY|MAY_BE_OBJECT|MAY_BE_RESOURCE|MAY_BE_REF))
       && opline->opcode == ZEND_ASSIGN_OP
       && opline->extended_value != ZEND_CONCAT) {

// op_1: ASSIGN_OP #orig_var.CV [undef,null,bool,int,double] -> #v.CV, ? => #v.CV = ADD #orig_var.CV, ?

        /* Reconstruct SSA */
        ssa->ops[op_1].result_def = ssa->ops[op_1].op1_def;
        ssa->ops[op_1].op1_def = -1;

        /* Update opcode */
        opline->opcode = opline->extended_value;
        opline->extended_value = 0;
        opline->result_type = opline->op1_type;
        opline->result.var = opline->op1.var;

      }
    }

#if ZEND_DEBUG_DFA
    ssa_verify_integrity(op_array, ssa, "after dfa");
#endif

    if (remove_nops) {
      zend_ssa_remove_nops(op_array, ssa, ctx);
#if ZEND_DEBUG_DFA
      ssa_verify_integrity(op_array, ssa, "after nop");
#endif
    }
  }

  if (ctx->debug_level & ZEND_DUMP_AFTER_DFA_PASS) {
    zend_dump_op_array(op_array, ZEND_DUMP_SSA, "after dfa pass", ssa);
  }
}

void zend_optimize_dfa(zend_op_array *op_array, zend_optimizer_ctx *ctx)
{
  void *checkpoint = zend_arena_checkpoint(ctx->arena);
  zend_ssa ssa;

  if (zend_dfa_analyze_op_array(op_array, ctx, &ssa) == FAILURE) {
    zend_arena_release(&ctx->arena, checkpoint);
    return;
  }

  zend_dfa_optimize_op_array(op_array, ctx, &ssa, NULL);

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

Coverage Report

Created: 2026-06-02 06:40