zend_dfg.c

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/*
   +----------------------------------------------------------------------+
   | Zend Engine, DFG - Data Flow Graph                                   |
   +----------------------------------------------------------------------+
   | Copyright (c) The PHP Group                                          |
   +----------------------------------------------------------------------+
   | This source file is subject to version 3.01 of the PHP license,      |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | https://www.php.net/license/3_01.txt                                 |
   | If you did not receive a copy of the PHP license and are unable to   |
   | obtain it through the world-wide-web, please send a note to          |
   | license@php.net so we can mail you a copy immediately.               |
   +----------------------------------------------------------------------+
   | Authors: Dmitry Stogov <dmitry@php.net>                              |
   +----------------------------------------------------------------------+
*/
 
#include "zend_compile.h"
#include "zend_dfg.h"
 
static zend_always_inline void _zend_dfg_add_use_def_op(const zend_op_array *op_array, const zend_op *opline, uint32_t build_flags, zend_bitset use, zend_bitset def) /* {{{ */
{
    uint32_t var_num;
    const zend_op *next;
 
    if (opline->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
        var_num = EX_VAR_TO_NUM(opline->op1.var);
        if (!zend_bitset_in(def, var_num)) {
            zend_bitset_incl(use, var_num);
        }
    }
    if (((opline->op2_type & (IS_VAR|IS_TMP_VAR)) != 0
      && opline->opcode != ZEND_FE_FETCH_R
      && opline->opcode != ZEND_FE_FETCH_RW)
     || (opline->op2_type == IS_CV)) {
        var_num = EX_VAR_TO_NUM(opline->op2.var);
        if (!zend_bitset_in(def, var_num)) {
            zend_bitset_incl(use, var_num);
        }
    }
    if ((build_flags & ZEND_SSA_USE_CV_RESULTS)
     && opline->result_type == IS_CV
     && opline->opcode != ZEND_RECV) {
        var_num = EX_VAR_TO_NUM(opline->result.var);
        if (!zend_bitset_in(def, var_num)) {
            zend_bitset_incl(use, var_num);
        }
    }
 
    switch (opline->opcode) {
        case ZEND_ASSIGN:
            if ((build_flags & ZEND_SSA_RC_INFERENCE) && opline->op2_type == IS_CV) {
                zend_bitset_incl(def, EX_VAR_TO_NUM(opline->op2.var));
            }
            if (opline->op1_type == IS_CV) {
add_op1_def:
                zend_bitset_incl(def, EX_VAR_TO_NUM(opline->op1.var));
            }
            break;
        case ZEND_ASSIGN_REF:
            if (opline->op2_type == IS_CV) {
                zend_bitset_incl(def, EX_VAR_TO_NUM(opline->op2.var));
            }
            if (opline->op1_type == IS_CV) {
                goto add_op1_def;
            }
            break;
        case ZEND_ASSIGN_DIM:
        case ZEND_ASSIGN_OBJ:
            next = opline + 1;
            if (next->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
                var_num = EX_VAR_TO_NUM(next->op1.var);
                if (!zend_bitset_in(def, var_num)) {
                    zend_bitset_incl(use, var_num);
                }
                if (build_flags & ZEND_SSA_RC_INFERENCE && next->op1_type == IS_CV) {
                    zend_bitset_incl(def, var_num);
                }
            }
            if (opline->op1_type == IS_CV) {
                goto add_op1_def;
            }
            break;
        case ZEND_ASSIGN_OBJ_REF:
            next = opline + 1;
            if (next->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
                var_num = EX_VAR_TO_NUM(next->op1.var);
                if (!zend_bitset_in(def, var_num)) {
                    zend_bitset_incl(use, var_num);
                }
                if (next->op1_type == IS_CV) {
                    zend_bitset_incl(def, var_num);
                }
            }
            if (opline->op1_type == IS_CV) {
                goto add_op1_def;
            }
            break;
        case ZEND_ASSIGN_STATIC_PROP:
            next = opline + 1;
            if (next->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
                var_num = EX_VAR_TO_NUM(next->op1.var);
                if (!zend_bitset_in(def, var_num)) {
                    zend_bitset_incl(use, var_num);
                }
                if ((build_flags & ZEND_SSA_RC_INFERENCE) && next->op1_type == IS_CV) {
                    zend_bitset_incl(def, var_num);
                }
            }
            break;
        case ZEND_ASSIGN_STATIC_PROP_REF:
            next = opline + 1;
            if (next->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
                var_num = EX_VAR_TO_NUM(next->op1.var);
                if (!zend_bitset_in(def, var_num)) {
                    zend_bitset_incl(use, var_num);
                }
                if (next->op1_type == IS_CV) {
                    zend_bitset_incl(def, var_num);
                }
            }
            break;
        case ZEND_ASSIGN_STATIC_PROP_OP:
        case ZEND_FRAMELESS_ICALL_3:
            next = opline + 1;
            if (next->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
                var_num = EX_VAR_TO_NUM(next->op1.var);
                if (!zend_bitset_in(def, var_num)) {
                    zend_bitset_incl(use, var_num);
                }
            }
            break;
        case ZEND_ASSIGN_DIM_OP:
        case ZEND_ASSIGN_OBJ_OP:
            next = opline + 1;
            if (next->op1_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
                var_num = EX_VAR_TO_NUM(next->op1.var);
                if (!zend_bitset_in(def, var_num)) {
                    zend_bitset_incl(use, var_num);
                }
            }
            if (opline->op1_type == IS_CV) {
                goto add_op1_def;
            }
            break;
        case ZEND_ASSIGN_OP:
        case ZEND_PRE_INC:
        case ZEND_PRE_DEC:
        case ZEND_POST_INC:
        case ZEND_POST_DEC:
        case ZEND_BIND_GLOBAL:
        case ZEND_BIND_STATIC:
        case ZEND_BIND_INIT_STATIC_OR_JMP:
        case ZEND_SEND_VAR_NO_REF:
        case ZEND_SEND_VAR_NO_REF_EX:
        case ZEND_SEND_VAR_EX:
        case ZEND_SEND_FUNC_ARG:
        case ZEND_SEND_REF:
        case ZEND_SEND_UNPACK:
        case ZEND_FE_RESET_RW:
        case ZEND_MAKE_REF:
        case ZEND_PRE_INC_OBJ:
        case ZEND_PRE_DEC_OBJ:
        case ZEND_POST_INC_OBJ:
        case ZEND_POST_DEC_OBJ:
        case ZEND_UNSET_DIM:
        case ZEND_UNSET_OBJ:
        case ZEND_FETCH_DIM_W:
        case ZEND_FETCH_DIM_RW:
        case ZEND_FETCH_DIM_FUNC_ARG:
        case ZEND_FETCH_DIM_UNSET:
        case ZEND_FETCH_LIST_W:
            if (opline->op1_type == IS_CV) {
                goto add_op1_def;
            }
            break;
        case ZEND_SEND_VAR:
        case ZEND_CAST:
        case ZEND_QM_ASSIGN:
        case ZEND_JMP_SET:
        case ZEND_COALESCE:
        case ZEND_FE_RESET_R:
            if ((build_flags & ZEND_SSA_RC_INFERENCE) && opline->op1_type == IS_CV) {
                goto add_op1_def;
            }
            break;
        case ZEND_ADD_ARRAY_UNPACK:
            var_num = EX_VAR_TO_NUM(opline->result.var);
            if (!zend_bitset_in(def, var_num)) {
                zend_bitset_incl(use, var_num);
            }
            break;
        case ZEND_ADD_ARRAY_ELEMENT:
            var_num = EX_VAR_TO_NUM(opline->result.var);
            if (!zend_bitset_in(def, var_num)) {
                zend_bitset_incl(use, var_num);
            }
            ZEND_FALLTHROUGH;
        case ZEND_INIT_ARRAY:
            if (((build_flags & ZEND_SSA_RC_INFERENCE)
                        || (opline->extended_value & ZEND_ARRAY_ELEMENT_REF))
                    && opline->op1_type == IS_CV) {
                goto add_op1_def;
            }
            break;
        case ZEND_YIELD:
            if (opline->op1_type == IS_CV
                    && ((op_array->fn_flags & ZEND_ACC_RETURN_REFERENCE)
                        || (build_flags & ZEND_SSA_RC_INFERENCE))) {
                goto add_op1_def;
            }
            break;
        case ZEND_UNSET_CV:
            goto add_op1_def;
        case ZEND_VERIFY_RETURN_TYPE:
            if (opline->op1_type & (IS_TMP_VAR|IS_VAR|IS_CV)) {
                goto add_op1_def;
            }
            break;
        case ZEND_FE_FETCH_R:
        case ZEND_FE_FETCH_RW:
#if 0
            /* This special case was handled above the switch */
            if (opline->op2_type != IS_CV) {
                op2_use = -1; /* not used */
            }
#endif
            zend_bitset_incl(def, EX_VAR_TO_NUM(opline->op2.var));
            break;
        case ZEND_BIND_LEXICAL:
            if ((opline->extended_value & ZEND_BIND_REF) || (build_flags & ZEND_SSA_RC_INFERENCE)) {
                zend_bitset_incl(def, EX_VAR_TO_NUM(opline->op2.var));
            }
            break;
        default:
            break;
    }
 
    if (opline->result_type & (IS_CV|IS_VAR|IS_TMP_VAR)) {
        zend_bitset_incl(def, EX_VAR_TO_NUM(opline->result.var));
    }
}
/* }}} */
 
ZEND_API void zend_dfg_add_use_def_op(const zend_op_array *op_array, const zend_op *opline, uint32_t build_flags, zend_bitset use, zend_bitset def) /* {{{ */
{
    _zend_dfg_add_use_def_op(op_array, opline, build_flags, use, def);
}
/* }}} */
 
void zend_build_dfg(const zend_op_array *op_array, const zend_cfg *cfg, zend_dfg *dfg, uint32_t build_flags) /* {{{ */
{
    int set_size;
    zend_basic_block *blocks = cfg->blocks;
    int blocks_count = cfg->blocks_count;
    zend_bitset tmp, def, use, in, out;
    int k;
    int j;
 
    set_size = dfg->size;
    tmp = dfg->tmp;
    def = dfg->def;
    use = dfg->use;
    in  = dfg->in;
    out = dfg->out;
 
    /* Collect "def" and "use" sets */
    for (j = 0; j < blocks_count; j++) {
        zend_op *opline, *end;
        zend_bitset b_use, b_def;
 
        if ((blocks[j].flags & ZEND_BB_REACHABLE) == 0) {
            continue;
        }
 
        opline = op_array->opcodes + blocks[j].start;
        end = opline + blocks[j].len;
        b_use = DFG_BITSET(use, set_size, j);
        b_def = DFG_BITSET(def, set_size, j);
        for (; opline < end; opline++) {
            if (opline->opcode != ZEND_OP_DATA) {
                _zend_dfg_add_use_def_op(op_array, opline, build_flags, b_use, b_def);
            }
        }
    }
 
    /* Calculate "in" and "out" sets */
    {
        uint32_t worklist_len = zend_bitset_len(blocks_count);
        zend_bitset worklist;
        ALLOCA_FLAG(use_heap);
        worklist = ZEND_BITSET_ALLOCA(worklist_len, use_heap);
        memset(worklist, 0, worklist_len * ZEND_BITSET_ELM_SIZE);
        for (j = 0; j < blocks_count; j++) {
            zend_bitset_incl(worklist, j);
        }
        while (!zend_bitset_empty(worklist, worklist_len)) {
            /* We use the last block on the worklist, because predecessors tend to be located
             * before the succeeding block, so this converges faster. */
            j = zend_bitset_last(worklist, worklist_len);
            zend_bitset_excl(worklist, j);
 
            if ((blocks[j].flags & ZEND_BB_REACHABLE) == 0) {
                continue;
            }
            if (blocks[j].successors_count != 0) {
                zend_bitset_copy(DFG_BITSET(out, set_size, j), DFG_BITSET(in, set_size, blocks[j].successors[0]), set_size);
                for (k = 1; k < blocks[j].successors_count; k++) {
                    zend_bitset_union(DFG_BITSET(out, set_size, j), DFG_BITSET(in, set_size, blocks[j].successors[k]), set_size);
                }
            } else {
                zend_bitset_clear(DFG_BITSET(out, set_size, j), set_size);
            }
            zend_bitset_union_with_difference(tmp, DFG_BITSET(use, set_size, j), DFG_BITSET(out, set_size, j), DFG_BITSET(def, set_size, j), set_size);
            if (!zend_bitset_equal(DFG_BITSET(in, set_size, j), tmp, set_size)) {
                zend_bitset_copy(DFG_BITSET(in, set_size, j), tmp, set_size);
 
                /* Add predecessors of changed block to worklist */
                {
                    int *predecessors = &cfg->predecessors[blocks[j].predecessor_offset];
                    for (k = 0; k < blocks[j].predecessors_count; k++) {
                        zend_bitset_incl(worklist, predecessors[k]);
                    }
                }
            }
        }
 
        free_alloca(worklist, use_heap);
    }
}
/* }}} */