function 的声明

<?php
function test()
{
    echo "abc";
}

test();
?>

结论:

一 编译

a.对 函数声明进行词法分析和语法分析：在语法分析中的函数zend_do_begin_function_declaration 作用是： 初始化zend_op_array,填充 function_name ,line_start ,设定相应opcode:ZEND_DECLARE_FUNCTION, 以key为function_name, value为 zend_op_array，存入CG(function_table)中;zend_do_end_function_declaration作用为： 填充zend_op_array中的line_end

b.对 函数调用进行词法分析和语法分析： 语法分析中的函数 zend_do_begin_function_call 作用是：将函数名转化为小写，zend_do_end_function_call中设定opcode:ZEND_DO_FCALL, op1为function_name,op2为no use

二 执行

c.执行a中的hanlder ZEND_DECLARE_FUNCTION,如果函数名重复出现，则报错

d.执行b中的handler ZEND_DO_FCALL ,

1)词法分析，提取function 关键字

<ST_IN_SCRIPTING>"function" {
    return T_FUNCTION;
        }

2)语法分析，每一个字符串表达式后面跟着一个方法，此方法是用来生成opcode

function:
　　T_FUNCTION { $$.u.op.opline_num = CG(zend_lineno); }
;

unticked_function_declaration_statement:
　　function is_reference T_STRING { zend_do_begin_function_declaration(&$, &$, , $.op_type, NULL TSRMLS_CC); }
          '(' parameter_list ')' '{' inner_statement_list '}' { zend_do_end_function_declaration(&$ TSRMLS_CC); }
;

parameter_list:
　　non_empty_parameter_list
   |    /* empty */
;

//用来处理参数
non_empty_parameter_list:
        optional_class_type T_VARIABLE                { $$.op_type = IS_UNUSED; $$.u.op.num=; zend_do_receive_arg(ZEND_RECV, &$, &$$, NULL, &$,  TSRMLS_CC); } //$$.u.op.num=1 说明是第一个参数，也只存在一个参数
    |    optional_class_type '&' T_VARIABLE            { $$.op_type = IS_UNUSED; $$.u.op.num=; zend_do_receive_arg(ZEND_RECV, &$, &$$, NULL, &$,  TSRMLS_CC); } //这种方法已经取消了，估计是向下兼容
    |    optional_class_type '&' T_VARIABLE '=' static_scalar            { $$.op_type = IS_UNUSED; $$.u.op.num=; zend_do_receive_arg(ZEND_RECV_INIT, &$, &$$, &$, &$,  TSRMLS_CC); }
    |    optional_class_type T_VARIABLE '=' static_scalar                { $$.op_type = IS_UNUSED; $$.u.op.num=; zend_do_receive_arg(ZEND_RECV_INIT, &$, &$$, &$, &$,  TSRMLS_CC); }
    |    non_empty_parameter_list ',' optional_class_type T_VARIABLE     { $$=$; $$.u.op.num++; zend_do_receive_arg(ZEND_RECV, &$, &$$, NULL, &$,  TSRMLS_CC); } // $$.u.op.num++递增，多个参数，用逗号分隔
    |    non_empty_parameter_list ',' optional_class_type '&' T_VARIABLE    { $$=$; $$.u.op.num++; zend_do_receive_arg(ZEND_RECV, &$, &$$, NULL, &$,  TSRMLS_CC); }
    |    non_empty_parameter_list ',' optional_class_type '&' T_VARIABLE     '=' static_scalar { $$=$; $$.u.op.num++; zend_do_receive_arg(ZEND_RECV_INIT, &$, &$$, &$, &$,  TSRMLS_CC); }
    |    non_empty_parameter_list ',' optional_class_type T_VARIABLE '=' static_scalar     { $$=$; $$.u.op.num++; zend_do_receive_arg(ZEND_RECV_INIT, &$, &$$, &$, &$,  TSRMLS_CC); }
;

对函数头进行语法分析 ，主要 往zend_op_array中填充信息，比如 函数开始行号

void zend_do_begin_function_declaration(znode *function_token, znode *function_name, int is_method, int return_reference, znode *fn_flags_znode TSRMLS_DC) /* {{{ */
        {
                zend_op_array op_array;
                char *name = function_name->u.constant.value.str.val;
                int name_len = function_name->u.constant.value.str.len;
                int function_begin_line = function_token->u.op.opline_num;
                zend_uint fn_flags;
                const char *lcname;
                zend_bool orig_interactive;
                ALLOCA_FLAG(use_heap)

                if (is_method) {
                        //忽略，这是针对类方法的

                        fn_flags = Z_LVAL(fn_flags_znode->u.constant); /* must be done *after* the above check */
                } else {
                        fn_flags = ;
                }
                if ((fn_flags & ZEND_ACC_STATIC) && (fn_flags & ZEND_ACC_ABSTRACT) && !(CG(active_class_entry)->ce_flags & ZEND_ACC_INTERFACE)) {
                        zend_error(E_STRICT, "Static function %s%s%s() should not be abstract", is_method ? CG(active_class_entry)->name : "", is_method ? "::" : "", Z_STRVAL(function_name->u.constant));
                }

                function_token->u.op_array = CG(active_op_array);//保存之前的CG(active_op_array),zend_do_end_funciton_declaration函数里将恢复CG(active_op_array)

                orig_interactive = CG(interactive);
                CG(interactive) = ;
                init_op_array(&op_array, ZEND_USER_FUNCTION, INITIAL_OP_ARRAY_SIZE TSRMLS_CC);
                CG(interactive) = orig_interactive;

               op_array.function_name = name; //填充functio_name字段

if (return_reference) {
                        op_array.fn_flags |= ZEND_ACC_RETURN_REFERENCE;
                }
                op_array.fn_flags |= fn_flags;

                op_array.scope = is_method?CG(active_class_entry):NULL;
                op_array.prototype = NULL;

                op_array.line_start = zend_get_compiled_lineno(TSRMLS_C); //填充 函数首行行号

                if (is_method) {
                     //忽略，这是针对类方法的处理

                } else {
                        zend_op *opline = get_next_op(CG(active_op_array) TSRMLS_CC);
                        zval key;

                        if (CG(current_namespace)) { //针对命名空间的
                                /* Prefix function name with current namespace name */
                                znode tmp;

                                tmp.u.constant = *CG(current_namespace);
                                zval_copy_ctor(&tmp.u.constant);
                                zend_do_build_namespace_name(&tmp, &tmp, function_name TSRMLS_CC);
                                op_array.function_name = Z_STRVAL(tmp.u.constant);
                                name_len = Z_STRLEN(tmp.u.constant);
                                lcname = zend_str_tolower_dup(Z_STRVAL(tmp.u.constant), name_len);
                        } else {

                                lcname = zend_str_tolower_dup(name, name_len); //函数名设置为小写
                        }

                        opline->opcode = ZEND_DECLARE_FUNCTION; //设置执行时的handler,在这里，如果函数名重复出现，会提示 已声明过函数了
                        opline->op1_type = IS_CONST;
                        build_runtime_defined_function_key(&key, lcname, name_len TSRMLS_CC);
                        opline->op1.constant = zend_add_literal(CG(active_op_array), &key TSRMLS_CC); //将key存入到zend_op_array中的literals中，他本身是个数组，即op1.constant是键，值是key
                        Z_HASH_P(&CONSTANT(opline->op1.constant)) = zend_hash_func(Z_STRVAL(CONSTANT(opline->op1.constant)), Z_STRLEN(CONSTANT(opline->op1.constant)));
                        opline->op2_type = IS_CONST;
                        LITERAL_STRINGL(opline->op2, lcname, name_len, ); //opline->op2.constant设置为 literals数组中的键,值为lcname
                        CALCULATE_LITERAL_HASH(opline->op2.constant);
                        opline->extended_value = ZEND_DECLARE_FUNCTION;

                        //放入CG中函数符号表，上面的key为 \0函数名文件名称，不知道为什么这样写？为什么不把函数名 直接存入 函数符号表？
                        zend_hash_quick_update(CG(function_table), Z_STRVAL(key), Z_STRLEN(key), Z_HASH_P(&CONSTANT(opline->op1.constant)), &op_array, sizeof(zend_op_array), (void **) &CG(active_op_array));
                        zend_stack_push(&CG(context_stack), (void *) &CG(context), sizeof(CG(context)));
                        zend_init_compiler_context(TSRMLS_C);
                }

                //忽略

                }
        }

ZEND_API char *zend_str_tolower_copy(char *dest, const char *source, unsigned int length) /* {{{ */
{
    register unsigned char *str = (unsigned char*)source;
    register unsigned char *result = (unsigned char*)dest;
    register unsigned char *end = str + length;

    while (str < end) {
        *result++ = zend_tolower((int)*str++);
    }
    *result = '\0';

    return dest;
}
/* }}} */

ZEND_API char *zend_str_tolower_dup(const char *source, unsigned int length) /* {{{ */
{
    return zend_str_tolower_copy((char *)emalloc(length+), source, length);
}

static void build_runtime_defined_function_key(zval *result, const char *name, int name_length TSRMLS_DC) /* {{{ */
{
    char char_pos_buf[];
    uint char_pos_len;
    const char *filename;

    char_pos_len = zend_sprintf(char_pos_buf, "%p", LANG_SCNG(yy_text));
    if (CG(active_op_array)->filename) {
        filename = CG(active_op_array)->filename;
    } else {
        filename = "-";
    }

    /* NULL, name length, filename length, last accepting char position length */
    result->value.str.len = +name_length+strlen(filename)+char_pos_len;

     /* must be binary safe */
     result->value.str.val = (char *) safe_emalloc(result->value.str.len, , );
     result->value.str.val[] = '\0';
     sprintf(result->value.str.val+, "%s%s%s", name, filename, char_pos_buf);

    result->type = IS_STRING;
    Z_SET_REFCOUNT_P(result, );
}

static inline void zend_insert_literal(zend_op_array *op_array, const zval *zv, int literal_position TSRMLS_DC) /* {{{ */
{
    if (Z_TYPE_P(zv) == IS_STRING || Z_TYPE_P(zv) == IS_CONSTANT) {
        zval *z = (zval*)zv;
        Z_STRVAL_P(z) = (char*)zend_new_interned_string(Z_STRVAL_P(zv), Z_STRLEN_P(zv) + ,  TSRMLS_CC);
    }
    CONSTANT_EX(op_array, literal_position) = *zv;
    Z_SET_REFCOUNT(CONSTANT_EX(op_array, literal_position), );
    Z_SET_ISREF(CONSTANT_EX(op_array, literal_position));
    op_array->literals[literal_position].hash_value = ;
    op_array->literals[literal_position].cache_slot = -;
}
/* }}} */

/* Is used while compiling a function, using the context to keep track
   of an approximate size to avoid to relocate to often.
   Literals are truncated to actual size in the second compiler pass (pass_two()). */
int  zend_add_literal(zend_op_array *op_array, const zval *zv TSRMLS_DC) /* {{{ */
{
    int i = op_array->last_literal;
    op_array->last_literal++;
    if (i >= CG(context).literals_size) {
        while (i >= CG(context).literals_size) {
            CG(context).literals_size += ; /* FIXME */
        }
        op_array->literals = (zend_literal*)erealloc(op_array->literals, CG(context).literals_size * sizeof(zend_literal));
    }
    zend_insert_literal(op_array, zv, i TSRMLS_CC);
    return i;
}

zend_op *get_next_op(zend_op_array *op_array TSRMLS_DC)
{
    zend_uint next_op_num = op_array->last++;
    zend_op *next_op;

    if (next_op_num >= CG(context).opcodes_size) {
        if (op_array->fn_flags & ZEND_ACC_INTERACTIVE) {
            /* we messed up */
            zend_printf("Ran out of opcode space!\n"
                        "You should probably consider writing this huge script into a file!\n");
            zend_bailout();
        }
        CG(context).opcodes_size *= ;
        op_array_alloc_ops(op_array, CG(context).opcodes_size);
    }

    next_op = &(op_array->opcodes[next_op_num]);

    init_op(next_op TSRMLS_CC);

    return next_op;
}

对函数体进行语法分析，主要是往zend_op_array中填充 函数结束行号，使用 pass_two函数，遍历CG(active_op_array)中的opcodes，设置zend_op 的handler

void zend_do_end_function_declaration(const znode *function_token TSRMLS_DC) /* {{{ */
{
    char lcname[];
    int name_len;

    zend_do_extended_info(TSRMLS_C);
    zend_do_return(NULL,  TSRMLS_CC);

    pass_two(CG(active_op_array) TSRMLS_CC);
    zend_release_labels(TSRMLS_C);

    if (CG(active_class_entry)) {
        zend_check_magic_method_implementation(CG(active_class_entry), (zend_function*)CG(active_op_array), E_COMPILE_ERROR TSRMLS_CC);
    } else {
        /* we don't care if the function name is longer, in fact lowercasing only
         * the beginning of the name speeds up the check process */
        name_len = strlen(CG(active_op_array)->function_name);
        zend_str_tolower_copy(lcname, CG(active_op_array)->function_name, MIN(name_len, sizeof(lcname)-));
        lcname[sizeof(lcname)-] = '\0'; /* zend_str_tolower_copy won't necessarily set the zero byte */
        if (name_len == sizeof(ZEND_AUTOLOAD_FUNC_NAME) -  && !memcmp(lcname, ZEND_AUTOLOAD_FUNC_NAME, sizeof(ZEND_AUTOLOAD_FUNC_NAME)) && CG(active_op_array)->num_args != ) {
            zend_error(E_COMPILE_ERROR, "%s() must take exactly 1 argument", ZEND_AUTOLOAD_FUNC_NAME);
        }
    }
    

    //得到函数体结束的 行
    CG(active_op_array)->line_end = zend_get_compiled_lineno(TSRMLS_C);
    CG(active_op_array) = function_token->u.op_array;

    /* Pop the switch and foreach seperators */
    zend_stack_del_top(&CG(switch_cond_stack));
    zend_stack_del_top(&CG(foreach_copy_stack));
}

ZEND_API int pass_two(zend_op_array *op_array TSRMLS_DC)
{
    zend_op *opline, *end;

    if (op_array->type!=ZEND_USER_FUNCTION && op_array->type!=ZEND_EVAL_CODE) {
        return ;
    }
    if (CG(compiler_options) & ZEND_COMPILE_EXTENDED_INFO) {
        zend_update_extended_info(op_array TSRMLS_CC);
    }
    if (CG(compiler_options) & ZEND_COMPILE_HANDLE_OP_ARRAY) {
        zend_llist_apply_with_argument(&zend_extensions, (llist_apply_with_arg_func_t) zend_extension_op_array_handler, op_array TSRMLS_CC);
    }

    if (!(op_array->fn_flags & ZEND_ACC_INTERACTIVE) && CG(context).vars_size != op_array->last_var) {
        op_array->vars = (zend_compiled_variable *) erealloc(op_array->vars, sizeof(zend_compiled_variable)*op_array->last_var);
        CG(context).vars_size = op_array->last_var;
    }
    if (!(op_array->fn_flags & ZEND_ACC_INTERACTIVE) && CG(context).opcodes_size != op_array->last) {
        op_array->opcodes = (zend_op *) erealloc(op_array->opcodes, sizeof(zend_op)*op_array->last);
        CG(context).opcodes_size = op_array->last;
    }
    if (!(op_array->fn_flags & ZEND_ACC_INTERACTIVE) && CG(context).literals_size != op_array->last_literal) {
        op_array->literals = (zend_literal*)erealloc(op_array->literals, sizeof(zend_literal) * op_array->last_literal);
        CG(context).literals_size = op_array->last_literal;
    }

    opline = op_array->opcodes;
    end = opline + op_array->last;
    while (opline < end) {
        if (opline->op1_type == IS_CONST) {
            opline->op1.zv = &op_array->literals[opline->op1.constant].constant;
        }
        if (opline->op2_type == IS_CONST) {
            opline->op2.zv = &op_array->literals[opline->op2.constant].constant;
        }
        switch (opline->opcode) {
            case ZEND_GOTO:
                if (Z_TYPE_P(opline->op2.zv) != IS_LONG) {
                    zend_resolve_goto_label(op_array, opline,  TSRMLS_CC);
                }
                /* break omitted intentionally */
            case ZEND_JMP:
                opline->op1.jmp_addr = &op_array->opcodes[opline->op1.opline_num];
                break;
            case ZEND_JMPZ:
            case ZEND_JMPNZ:
            case ZEND_JMPZ_EX:
            case ZEND_JMPNZ_EX:
            case ZEND_JMP_SET:
            case ZEND_JMP_SET_VAR:
                opline->op2.jmp_addr = &op_array->opcodes[opline->op2.opline_num];
                break;
        }
        ZEND_VM_SET_OPCODE_HANDLER(opline);
        opline++;
    }

    op_array->fn_flags |= ZEND_ACC_DONE_PASS_TWO;
    return ;
}

ZEND_API void zend_vm_set_opcode_handler(zend_op* op)
{
    op->handler = zend_vm_get_opcode_handler(zend_user_opcodes[op->opcode], op);
}

static opcode_handler_t zend_vm_get_opcode_handler(zend_uchar opcode, zend_op* op)
{
        static const int zend_vm_decode[] = {
            _UNUSED_CODE, /* 0              */
            _CONST_CODE,  /* 1 = IS_CONST   */
            _TMP_CODE,    /* 2 = IS_TMP_VAR */
            _UNUSED_CODE, /* 3              */
            _VAR_CODE,    /* 4 = IS_VAR     */
            _UNUSED_CODE, /* 5              */
            _UNUSED_CODE, /* 6              */
            _UNUSED_CODE, /* 7              */
            _UNUSED_CODE, /* 8 = IS_UNUSED  */
            _UNUSED_CODE, /* 9              */
            _UNUSED_CODE, /* 10             */
            _UNUSED_CODE, /* 11             */
            _UNUSED_CODE, /* 12             */
            _UNUSED_CODE, /* 13             */
            _UNUSED_CODE, /* 14             */
            _UNUSED_CODE, /* 15             */
            _CV_CODE      /* 16 = IS_CV     */
        };
        return zend_opcode_handlers[opcode *  + zend_vm_decode[op->op1_type] *  + zend_vm_decode[op->op2_type]]; //通过 zend_op中的opcode 和左右值类型 ，计算出实际的handler;zend_opcode_handlers是一个巨大的数组，里面都是指针函数
}

如果函数体中，还有其他数据，例如赋值，就把相应opcode放到zend_op_array中的opcodes中

static int ZEND_FASTCALL  ZEND_DECLARE_FUNCTION_SPEC_HANDLER(ZEND_OPCODE_HANDLER_ARGS)
{
    USE_OPLINE

    SAVE_OPLINE();
    do_bind_function(EX(op_array), opline, EG(function_table), );
    CHECK_EXCEPTION();
    ZEND_VM_NEXT_OPCODE();
}

//在执行期间，将函数名放入 EG(function_table)中，如果发现已经有了，则报错

ZEND_API int do_bind_function(const zend_op_array *op_array, zend_op *opline, HashTable *function_table, zend_bool compile_time) /* {{{ */
{
    zend_function *function;
    zval *op1, *op2;

    if (compile_time) {
        op1 = &CONSTANT_EX(op_array, opline->op1.constant);
        op2 = &CONSTANT_EX(op_array, opline->op2.constant);
    } else {
        op1 = opline->op1.zv; //这里的op1.zv的值是通过上面的pass_two这个函数中得到的，他会遍历zend_op_array中的opcodes,如果op1_type为 IS_CONST，就会进行把zend_op_array中的literals相应的值赋给op1.zv
        op2 = opline->op2.zv; //同上
    }

    //这里的op1为上面的\0函数名文件名称，从EG(function_table)中取出，值赋给function
    zend_hash_quick_find(function_table, Z_STRVAL_P(op1), Z_STRLEN_P(op1), Z_HASH_P(op1), (void *) &function);
    //将键为op2（只有函数名），值为function,插入到EG(function)中，如果插入失败，说明函数多次被插入，要报函数已被声明的提示
    if (zend_hash_quick_add(function_table, Z_STRVAL_P(op2), Z_STRLEN_P(op2)+, Z_HASH_P(op2), function, sizeof(zend_function), NULL)==FAILURE) {
        int error_level = compile_time ? E_COMPILE_ERROR : E_ERROR;
        zend_function *old_function;

        if (zend_hash_quick_find(function_table, Z_STRVAL_P(op2), Z_STRLEN_P(op2)+, Z_HASH_P(op2), (void *) &old_function)==SUCCESS
            && old_function->type == ZEND_USER_FUNCTION
            && old_function->op_array.last > ) {
            zend_error(error_level, "Cannot redeclare %s() (previously declared in %s:%d)",
                        function->common.function_name,
                        old_function->op_array.filename,
                        old_function->op_array.opcodes[].lineno);
        } else {
            zend_error(error_level, "Cannot redeclare %s()", function->common.function_name);
        }
        return FAILURE;
    } else {
        (*function->op_array.refcount)++;
        function->op_array.static_variables = NULL; /* NULL out the unbound function */
        return SUCCESS;
    }
}

对于 调用函数时的编译

function_call:
        namespace_name '(' { $.u.op.opline_num = zend_do_begin_function_call(&$,  TSRMLS_CC); }
                function_call_parameter_list
                ')' { zend_do_end_function_call(&$, &$$, &$, , $.u.op.opline_num TSRMLS_CC); zend_do_extended_fcall_end(TSRMLS_C); }
    |    T_NAMESPACE T_NS_SEPARATOR namespace_name '(' { $.op_type = IS_CONST; ZVAL_EMPTY_STRING(&$.u.constant);  zend_do_build_namespace_name(&$, &$, &$ TSRMLS_CC); $.u.op.opline_num = zend_do_begin_function_call(&$,  TSRMLS_CC); }
                function_call_parameter_list
                ')' { zend_do_end_function_call(&$, &$$, &$, , $.u.op.opline_num TSRMLS_CC); zend_do_extended_fcall_end(TSRMLS_C); }
    |    T_NS_SEPARATOR namespace_name '(' { $.u.op.opline_num = zend_do_begin_function_call(&$,  TSRMLS_CC); }
                function_call_parameter_list
                ')' { zend_do_end_function_call(&$, &$$, &$, , $.u.op.opline_num TSRMLS_CC); zend_do_extended_fcall_end(TSRMLS_C); }
    |    class_name T_PAAMAYIM_NEKUDOTAYIM variable_name '(' { $.u.op.opline_num = zend_do_begin_class_member_function_call(&$, &$ TSRMLS_CC); }
            function_call_parameter_list
            ')' { zend_do_end_function_call($.u.op.opline_num?NULL:&$, &$$, &$, $.u.op.opline_num, $.u.op.opline_num TSRMLS_CC); zend_do_extended_fcall_end(TSRMLS_C);}
    |    class_name T_PAAMAYIM_NEKUDOTAYIM variable_without_objects '(' { zend_do_end_variable_parse(&$, BP_VAR_R,  TSRMLS_CC); zend_do_begin_class_member_function_call(&$, &$ TSRMLS_CC); }
            function_call_parameter_list
            ')' { zend_do_end_function_call(NULL, &$$, &$, ,  TSRMLS_CC); zend_do_extended_fcall_end(TSRMLS_C);}
    |    variable_class_name T_PAAMAYIM_NEKUDOTAYIM variable_name '(' { zend_do_begin_class_member_function_call(&$, &$ TSRMLS_CC); }
            function_call_parameter_list
            ')' { zend_do_end_function_call(NULL, &$$, &$, ,  TSRMLS_CC); zend_do_extended_fcall_end(TSRMLS_C);}
    |    variable_class_name T_PAAMAYIM_NEKUDOTAYIM variable_without_objects '(' { zend_do_end_variable_parse(&$, BP_VAR_R,  TSRMLS_CC); zend_do_begin_class_member_function_call(&$, &$ TSRMLS_CC); }
            function_call_parameter_list
            ')' { zend_do_end_function_call(NULL, &$$, &$, ,  TSRMLS_CC); zend_do_extended_fcall_end(TSRMLS_C);}
    |    variable_without_objects  '(' { zend_do_end_variable_parse(&$, BP_VAR_R,  TSRMLS_CC); zend_do_begin_dynamic_function_call(&$,  TSRMLS_CC); }
            function_call_parameter_list ')'
            { zend_do_end_function_call(&$, &$$, &$, ,  TSRMLS_CC); zend_do_extended_fcall_end(TSRMLS_C);}
;

int zend_do_begin_function_call(znode *function_name, zend_bool check_namespace TSRMLS_DC) /* {{{ */
{
    zend_function *function;
    char *lcname;
    char *is_compound = memchr(Z_STRVAL(function_name->u.constant), '\\', Z_STRLEN(function_name->u.constant));

    zend_resolve_non_class_name(function_name, check_namespace TSRMLS_CC);

    if (check_namespace && CG(current_namespace) && !is_compound) {
            /* We assume we call function from the current namespace
            if it is not prefixed. */

            /* In run-time PHP will check for function with full name and
            internal function with short name */
            zend_do_begin_dynamic_function_call(function_name,  TSRMLS_CC);
            return ;
    } 

    lcname = zend_str_tolower_dup(function_name->u.constant.value.str.val, function_name->u.constant.value.str.len); //将函数名称转化为小写，因为调用的时候，函数名可能是大写的
    if ((zend_hash_find(CG(function_table), lcname, function_name->u.constant.value.str.len+, (void **) &function)==FAILURE) ||
         ((CG(compiler_options) & ZEND_COMPILE_IGNORE_INTERNAL_FUNCTIONS) &&
         (function->type == ZEND_INTERNAL_FUNCTION))) {
             zend_do_begin_dynamic_function_call(function_name,  TSRMLS_CC);
             efree(lcname);
             return ; /* Dynamic */
     }
    efree(function_name->u.constant.value.str.val);
    function_name->u.constant.value.str.val = lcname;

    zend_stack_push(&CG(function_call_stack), (void *) &function, sizeof(zend_function *));
    zend_do_extended_fcall_begin(TSRMLS_C);
    return ;
}

ZEND_API int zend_stack_push(zend_stack *stack, const void *element, int size)
{
    if (stack->top >= stack->max) {        /* we need to allocate more memory */
        stack->elements = (void **) erealloc(stack->elements,
                   (sizeof(void **) * (stack->max += STACK_BLOCK_SIZE)));
        if (!stack->elements) {
            return FAILURE;
        }
    }
    stack->elements[stack->top] = (void *) emalloc(size);
    memcpy(stack->elements[stack->top], element, size);
    return stack->top++;
}

typedef struct _zend_stack {
    int top, max;
    void **elements;
} zend_stack;

void zend_do_end_function_call(znode *function_name, znode *result, const znode *argument_list, int is_method, int is_dynamic_fcall TSRMLS_DC) /* {{{ */
{
    zend_op *opline;

    if (is_method && function_name && function_name->op_type == IS_UNUSED) { //类方法
        /* clone */
        if (Z_LVAL(argument_list->u.constant) != ) {
            zend_error(E_WARNING, "Clone method does not require arguments");
        }
        opline = &CG(active_op_array)->opcodes[Z_LVAL(function_name->u.constant)];
    } else { //普通方法
        opline = get_next_op(CG(active_op_array) TSRMLS_CC);
        if (!is_method && !is_dynamic_fcall && function_name->op_type==IS_CONST) {
            opline->opcode = ZEND_DO_FCALL; //设置执行时的handler
            SET_NODE(opline->op1, function_name); //设置左值为 方法的名称
            CALCULATE_LITERAL_HASH(opline->op1.constant);
            GET_CACHE_SLOT(opline->op1.constant);
        } else {
            opline->opcode = ZEND_DO_FCALL_BY_NAME;
            SET_UNUSED(opline->op1);
        }
    }

    opline->result.var = get_temporary_variable(CG(active_op_array));
    opline->result_type = IS_VAR;
    GET_NODE(result, opline->result)    ;
    SET_UNUSED(opline->op2);

    zend_stack_del_top(&CG(function_call_stack));
    opline->extended_value = Z_LVAL(argument_list->u.constant);
}

#define CONSTANT_EX(op_array, op) \
    (op_array)->literals[op].constant

#define CONSTANT(op) \
    CONSTANT_EX(CG(active_op_array), op)

#define SET_NODE(target, src) do { \
        target ## _type = (src)->op_type; \
        if ((src)->op_type == IS_CONST) { \
            target.constant = zend_add_literal(CG(active_op_array), &(src)->u.constant TSRMLS_CC); \
        } else { \
            target = (src)->u.op; \
        } \
    } while ()

#define GET_NODE(target, src) do { \
        (target)->op_type = src ## _type; \
        if ((target)->op_type == IS_CONST) { \
            (target)->u.constant = CONSTANT(src.constant); \
        } else { \
            (target)->u.op = src; \
            (target)->EA = ; \
        } \
    } while ()

static zend_uint get_temporary_variable(zend_op_array *op_array) /* {{{ */
{
    return (op_array->T)++ * ZEND_MM_ALIGNED_SIZE(sizeof(temp_variable));
}

zend_op *get_next_op(zend_op_array *op_array TSRMLS_DC)
{
    zend_uint next_op_num = op_array->last++;
    zend_op *next_op;

    if (next_op_num >= CG(context).opcodes_size) {
        if (op_array->fn_flags & ZEND_ACC_INTERACTIVE) {
            /* we messed up */
            zend_printf("Ran out of opcode space!\n"
                        "You should probably consider writing this huge script into a file!\n");
            zend_bailout();
        }
        CG(context).opcodes_size *= ;
        op_array_alloc_ops(op_array, CG(context).opcodes_size);
    }

    next_op = &(op_array->opcodes[next_op_num]);

    init_op(next_op TSRMLS_CC);

    return next_op;
}

void init_op(zend_op *op TSRMLS_DC)
{
    memset(op, , sizeof(zend_op)); //初始化
    op->lineno = CG(zend_lineno);
    SET_UNUSED(op->result);
}

typedef struct _zend_file_handle {
    zend_stream_type  type;
    const char        *filename;
    char              *opened_path;
    union {
        int           fd;
        FILE          *fp;
        zend_stream   stream;
    } handle;
    zend_bool free_filename;
} zend_file_handle;

void init_op_array(zend_op_array *op_array, zend_uchar type, int initial_ops_size TSRMLS_DC)
{
    op_array->type = type;

    if (CG(interactive)) {
        /* We must avoid a realloc() on the op_array in interactive mode, since pointers to constants
         * will become invalid
         */
        initial_ops_size = INITIAL_INTERACTIVE_OP_ARRAY_SIZE;
    }

    op_array->refcount = (zend_uint *) emalloc(sizeof(zend_uint));
    *op_array->refcount = ;
    op_array->last = ;
    op_array->opcodes = NULL;
    op_array_alloc_ops(op_array, initial_ops_size);

    op_array->last_var = ;
    op_array->vars = NULL;

    op_array->T = ;

    op_array->function_name = NULL;
    op_array->filename = zend_get_compiled_filename(TSRMLS_C);
    op_array->doc_comment = NULL;
    op_array->doc_comment_len = ;

    op_array->arg_info = NULL;
    op_array->num_args = ;
    op_array->required_num_args = ;

    op_array->scope = NULL;

    op_array->brk_cont_array = NULL;
    op_array->try_catch_array = NULL;
    op_array->last_brk_cont = ;

    op_array->static_variables = NULL;
    op_array->last_try_catch = ;

    op_array->this_var = -;

    op_array->fn_flags = CG(interactive)?ZEND_ACC_INTERACTIVE:;

    op_array->early_binding = -;

    op_array->last_literal = ;
    op_array->literals = NULL;

    op_array->run_time_cache = NULL;
    op_array->last_cache_slot = ;

    memset(op_array->reserved, , ZEND_MAX_RESERVED_RESOURCES * sizeof(void*));

    zend_llist_apply_with_argument(&zend_extensions, (llist_apply_with_arg_func_t) zend_extension_op_array_ctor_handler, op_array TSRMLS_CC);
}

执行 opcode

static int ZEND_FASTCALL  ZEND_DO_FCALL_SPEC_CONST_HANDLER(ZEND_OPCODE_HANDLER_ARGS)
{
    USE_OPLINE

    zval *fname = opline->op1.zv;

    zend_ptr_stack_3_push(&EG(arg_types_stack), EX(fbc), EX(object), EX(called_scope));

    if (CACHED_PTR(opline->op1.literal->cache_slot)) {
        EX(function_state).function = CACHED_PTR(opline->op1.literal->cache_slot);
    } else if (UNEXPECTED(zend_hash_quick_find(EG(function_table), Z_STRVAL_P(fname), Z_STRLEN_P(fname)+, Z_HASH_P(fname), (void **) &EX(function_state).function)==FAILURE)) {

        //上面的zend_hash_quick_find很重要，从EG（function_table)中取出key为fname的value值，并将些值放入EX(fucntion_state)的function中
        SAVE_OPLINE();
        zend_error_noreturn(E_ERROR, "Call to undefined function %s()", fname->value.str.val);
    } else {
        CACHE_PTR(opline->op1.literal->cache_slot, EX(function_state).function); //放入原生态C数组中，因为会有第二次调用函数
    }
    EX(object) = NULL;

    return zend_do_fcall_common_helper_SPEC(ZEND_OPCODE_HANDLER_ARGS_PASSTHRU);
}

static int ZEND_FASTCALL zend_do_fcall_common_helper_SPEC(ZEND_OPCODE_HANDLER_ARGS)
{
    USE_OPLINE
    zend_bool should_change_scope = ;
    zend_function *fbc = EX(function_state).function;

    SAVE_OPLINE();
    if (UNEXPECTED((fbc->common.fn_flags & (ZEND_ACC_ABSTRACT|ZEND_ACC_DEPRECATED)) != )) {
        if (UNEXPECTED((fbc->common.fn_flags & ZEND_ACC_ABSTRACT) != )) {
            zend_error_noreturn(E_ERROR, "Cannot call abstract method %s::%s()", fbc->common.scope->name, fbc->common.function_name);
            CHECK_EXCEPTION();
            ZEND_VM_NEXT_OPCODE(); /* Never reached */
        }
        if (UNEXPECTED((fbc->common.fn_flags & ZEND_ACC_DEPRECATED) != )) {
            zend_error(E_DEPRECATED, "Function %s%s%s() is deprecated",
                fbc->common.scope ? fbc->common.scope->name : "",
                fbc->common.scope ? "::" : "",
                fbc->common.function_name);
        }
    }
    if (fbc->common.scope &&
        !(fbc->common.fn_flags & ZEND_ACC_STATIC) &&
        !EX(object)) {

        if (fbc->common.fn_flags & ZEND_ACC_ALLOW_STATIC) {
            /* FIXME: output identifiers properly */
            zend_error(E_STRICT, "Non-static method %s::%s() should not be called statically", fbc->common.scope->name, fbc->common.function_name);
        } else {
            /* FIXME: output identifiers properly */
            /* An internal function assumes $this is present and won't check that. So PHP would crash by allowing the call. */
            zend_error_noreturn(E_ERROR, "Non-static method %s::%s() cannot be called statically", fbc->common.scope->name, fbc->common.function_name);
        }
    }

    if (fbc->type == ZEND_USER_FUNCTION || fbc->common.scope) {
        should_change_scope = ;
        EX(current_this) = EG(This);
        EX(current_scope) = EG(scope);
        EX(current_called_scope) = EG(called_scope);
        EG(This) = EX(object);
        EG(scope) = (fbc->type == ZEND_USER_FUNCTION || !EX(object)) ? fbc->common.scope : NULL;
        EG(called_scope) = EX(called_scope);
    }

    zend_arg_types_stack_3_pop(&EG(arg_types_stack), &EX(called_scope), &EX(current_object), &EX(fbc));
    EX(function_state).arguments = zend_vm_stack_push_args(opline->extended_value TSRMLS_CC);
    LOAD_OPLINE();

    if (fbc->type == ZEND_INTERNAL_FUNCTION) { //php内部函数
        temp_variable *ret = &EX_T(opline->result.var);

        if (fbc->common.arg_info) {
            zend_uint i=;
            zval **p = (zval**)EX(function_state).arguments;
            ulong arg_count = opline->extended_value;

            while (arg_count>) {
                zend_verify_arg_type(fbc, ++i, *(p-arg_count),  TSRMLS_CC);
                arg_count--;
            }
        }

        if (EXPECTED(EG(exception) == NULL)) {
            MAKE_STD_ZVAL(ret->var.ptr);
            ZVAL_NULL(ret->var.ptr);
            ret->var.ptr_ptr = &ret->var.ptr;
            ret->var.fcall_returned_reference = (fbc->common.fn_flags & ZEND_ACC_RETURN_REFERENCE) != ;

            if (!zend_execute_internal) {
                /* saves one function call if zend_execute_internal is not used */
                fbc->internal_function.handler(opline->extended_value, ret->var.ptr, (fbc->common.fn_flags & ZEND_ACC_RETURN_REFERENCE) ? &ret->var.ptr : NULL, EX(object), RETURN_VALUE_USED(opline) TSRMLS_CC);
            } else {
                zend_execute_internal(execute_data, RETURN_VALUE_USED(opline) TSRMLS_CC);
            }

            if (!RETURN_VALUE_USED(opline)) {
                zval_ptr_dtor(&ret->var.ptr);
            }
        } else if (RETURN_VALUE_USED(opline)) {
            EX_T(opline->result.var).var.ptr = NULL;
        }
    } else if (fbc->type == ZEND_USER_FUNCTION) { //php算定义的函数
        EX(original_return_value) = EG(return_value_ptr_ptr);
        EG(active_symbol_table) = NULL;
        EG(active_op_array) = &fbc->op_array;
        EG(return_value_ptr_ptr) = NULL;
        if (RETURN_VALUE_USED(opline)) {
            temp_variable *ret = &EX_T(opline->result.var);

            ret->var.ptr = NULL;
            EG(return_value_ptr_ptr) = &ret->var.ptr;
            ret->var.ptr_ptr = &ret->var.ptr;
            ret->var.fcall_returned_reference = (fbc->common.fn_flags & ZEND_ACC_RETURN_REFERENCE) != ;
        }

        if (EXPECTED(zend_execute == execute)) {
            if (EXPECTED(EG(exception) == NULL)) {
                ZEND_VM_ENTER();
            }
        } else {
            zend_execute(EG(active_op_array) TSRMLS_CC);
        }

        EG(opline_ptr) = &EX(opline);
        EG(active_op_array) = EX(op_array);
        EG(return_value_ptr_ptr) = EX(original_return_value);
        if (EG(active_symbol_table)) {
            if (EG(symtable_cache_ptr)>=EG(symtable_cache_limit)) {
                zend_hash_destroy(EG(active_symbol_table));
                FREE_HASHTABLE(EG(active_symbol_table));
            } else {
                /* clean before putting into the cache, since clean
                   could call dtors, which could use cached hash */
                zend_hash_clean(EG(active_symbol_table));
                *(++EG(symtable_cache_ptr)) = EG(active_symbol_table);
            }
        }
        EG(active_symbol_table) = EX(symbol_table);
    } else { /* ZEND_OVERLOADED_FUNCTION */
        MAKE_STD_ZVAL(EX_T(opline->result.var).var.ptr);
        ZVAL_NULL(EX_T(opline->result.var).var.ptr);

            /* Not sure what should be done here if it's a static method */
        if (EXPECTED(EX(object) != NULL)) {
            Z_OBJ_HT_P(EX(object))->call_method(fbc->common.function_name, opline->extended_value, EX_T(opline->result.var).var.ptr, &EX_T(opline->result.var).var.ptr, EX(object), RETURN_VALUE_USED(opline) TSRMLS_CC);
        } else {
            zend_error_noreturn(E_ERROR, "Cannot call overloaded function for non-object");
        }

        if (fbc->type == ZEND_OVERLOADED_FUNCTION_TEMPORARY) {
            efree((char*)fbc->common.function_name);
        }
        efree(fbc);

        if (!RETURN_VALUE_USED(opline)) {
            zval_ptr_dtor(&EX_T(opline->result.var).var.ptr);
        } else {
            Z_UNSET_ISREF_P(EX_T(opline->result.var).var.ptr);
            Z_SET_REFCOUNT_P(EX_T(opline->result.var).var.ptr, );
            EX_T(opline->result.var).var.fcall_returned_reference = ;
            EX_T(opline->result.var).var.ptr_ptr = &EX_T(opline->result.var).var.ptr;
        }
    }

    EX(function_state).function = (zend_function *) EX(op_array);
    EX(function_state).arguments = NULL;

    if (should_change_scope) {
        if (EG(This)) {
            if (UNEXPECTED(EG(exception) != NULL) && IS_CTOR_CALL(EX(called_scope))) {
                if (IS_CTOR_USED(EX(called_scope))) {
                    Z_DELREF_P(EG(This));
                }
                if (Z_REFCOUNT_P(EG(This)) == ) {
                    zend_object_store_ctor_failed(EG(This) TSRMLS_CC);
                }
            }
            zval_ptr_dtor(&EG(This));
        }
        EG(This) = EX(current_this);
        EG(scope) = EX(current_scope);
        EG(called_scope) = EX(current_called_scope);
    }

    EX(object) = EX(current_object);
    EX(called_scope) = DECODE_CTOR(EX(called_scope));

    zend_vm_stack_clear_multiple(TSRMLS_C);

    if (UNEXPECTED(EG(exception) != NULL)) {
        zend_throw_exception_internal(NULL TSRMLS_CC);
        if (RETURN_VALUE_USED(opline) && EX_T(opline->result.var).var.ptr) {
            zval_ptr_dtor(&EX_T(opline->result.var).var.ptr);
        }
        HANDLE_EXCEPTION();
    }

    ZEND_VM_NEXT_OPCODE();
}

void init_executor(TSRMLS_D) /* {{{ */
{
    zend_init_fpu(TSRMLS_C);

    INIT_ZVAL(EG(uninitialized_zval));
    /* trick to make uninitialized_zval never be modified, passed by ref, etc. */
    Z_ADDREF(EG(uninitialized_zval));
    INIT_ZVAL(EG(error_zval));
    EG(uninitialized_zval_ptr)=&EG(uninitialized_zval);
    EG(error_zval_ptr)=&EG(error_zval);
    zend_ptr_stack_init(&EG(arg_types_stack));
/* destroys stack frame, therefore makes core dumps worthless */
#if 0&&ZEND_DEBUG
    original_sigsegv_handler = signal(SIGSEGV, zend_handle_sigsegv);
#endif
    EG(return_value_ptr_ptr) = NULL;

    EG(symtable_cache_ptr) = EG(symtable_cache) - ;
    EG(symtable_cache_limit) = EG(symtable_cache) + SYMTABLE_CACHE_SIZE - ;
    EG(no_extensions) = ;

    EG(function_table) = CG(function_table); //很重要
    EG(class_table) = CG(class_table);

    EG(in_execution) = ;
    EG(in_autoload) = NULL;
    EG(autoload_func) = NULL;
    EG(error_handling) = EH_NORMAL;

    zend_vm_stack_init(TSRMLS_C);
    zend_vm_stack_push((void *) NULL TSRMLS_CC);

    zend_hash_init(&EG(symbol_table), , NULL, ZVAL_PTR_DTOR, );
    EG(active_symbol_table) = &EG(symbol_table);

    zend_llist_apply(&zend_extensions, (llist_apply_func_t) zend_extension_activator TSRMLS_CC);
    EG(opline_ptr) = NULL;

    zend_hash_init(&EG(included_files), , NULL, NULL, );

    EG(ticks_count) = ;

    EG(user_error_handler) = NULL;

    EG(current_execute_data) = NULL;

    zend_stack_init(&EG(user_error_handlers_error_reporting));
    zend_ptr_stack_init(&EG(user_error_handlers));
    zend_ptr_stack_init(&EG(user_exception_handlers));

    zend_objects_store_init(&EG(objects_store), );

    EG(full_tables_cleanup) = ;
#ifdef ZEND_WIN32
    EG(timed_out) = ;
#endif

    EG(exception) = NULL;
    EG(prev_exception) = NULL;

    EG(scope) = NULL;
    EG(called_scope) = NULL;

    EG(This) = NULL;

    EG(active_op_array) = NULL;

    EG(active) = ;
    EG(start_op) = NULL;
}

struct _zend_vm_stack {
    void **top;
    void **end;
    zend_vm_stack prev;
};

static zend_always_inline void zend_vm_stack_push(void *ptr TSRMLS_DC)
{
    ZEND_VM_STACK_GROW_IF_NEEDED();
    *(EG(argument_stack)->top++) = ptr;
}

http://www.cnblogs.com/driftcloudy/p/3213504.html

函数传递参数入栈的原理

http://www.laruence.com/2010/01/03/1225.html

http://blog.sina.com.cn/s/blog_6ecf35840100m669.html 传值，传引用

http://www.phppan.com/2012/04/php-compiled-variable/ cv

本文主要参考“风雪之域”Laruence的文章。转载：http://www.laruence.com/2008/04/01/116.html

我们刚学php的时候，学到函数时，常会向里面传参数。比如function example($a,$b).那到底a和b的参数是怎么传入到example函数以及函数是怎么接受的呢，下面来为大家揭秘。

在 Zend/zend_language_scanner.l中我们会找到如下所示的代码：

<ST_IN_SCRipTING>

"function" {
    return T_FUNCTION;

}

它所表示的含义是function将会生成T_FUNCTION标记。T_FUNCTION标记只是用来定义函数的生命，标明这是一个函数，更多的东西则是参数，返回值等等。

当php等高级语言被编译成机器码时面临一个问题，cpu不能识别函数怎么传参，传的几个参数，传递参数的工作必须由函数调用者或函数本书来完成。当函数调用时，调用者依次把参数压栈，然后调用函数，调用后，在堆栈中取得数据，并进行计算。函数计算完成后，由调用者或者函数本身修改堆栈，使堆栈恢复原状。在参数传递过程中，有下列三个问题需要注意：

1：参数多余一个时，传递参数的顺序

2：函数调用后，谁来恢复堆栈

3：函数的返回值放在什么地方。

在高级语言中，通过函数调用规范来说明这几个问题。常见的调用规范有下面几个：

stdcall、cdecl、fastcall、thiscall、naked call

具体的调用规范大家可以参考具体的例子，这里只是把这几个问题的答案说出来

1：传递参数是由后到前传递。function example($a,$b).中，先把$b压栈再把$a压栈

2：由相关的规范决定