PHPの緩やかな比較の実態

Copyright© M&AΫϥ΢υ
PHPͷ؇΍͔ͳൺֱͷ࣮ଶ
PHPerKaigi 2022

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Copyright© M&AΫϥ΢υ 2
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גࣜձࣾM&AΫϥ΢υ
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fyui001
@fyui_001

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֓ཁ
PHPʹ͸౳Ձԋࢉࢠ͕2ͭ͋Γ·͢ɻʮ==ʯͱʮ===ʯͰ͢ɻ
લऀ͸؇΍͔ͳൺֱɺޙऀ͸ݫີͳൺֱ͕ߦΘΕ·͢ɻ
PHPerͷํͳΒΑ͘͝ଘ஌ͩͱࢥ͍·͢ɻ
ࠓճ͸લऀͷ؇΍͔ͳൺֱΛ࣮ଶ͕Ͳ͏ͳ͍ͬͯΔͷ͔Λ௥ͬͯݟ͍ͨͱࢥ͍·͢ɻ

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؇΍͔ͳൺֱͷΧΦε͞
ྫ:

var_dump(0 == '00');

var_dump('00' == '0000');

var_dump('01' == '001');

ग़ྗ:

bool(true)

bool(true)

bool(true)

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؇΍͔ͳൺֱͷΧΦε͞
͸͍ɺҙຯΘ͔Γ·ͤΜɻ
1, 2ߦ໨͸ཧղͰ͖ͳ͍͜ͱ΋͋Γ·ͤΜ͕
3ߦ໨͕ԿނtrueʹͳΔͷ͔ɺݫີʹઆ໌͢Δʹ͸Ͳ͏ͨ͠Β͍͍Ͱ͠ΐ
͏͔ɻ
͜ͷൃදΛฉ͍ͯཧղ͠આ໌Ͱ͖ΔΑ͏ʹͳͬͯ໯͑Ε͹خ͍͠Ͱ͢ɻ

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؇΍͔ͳൺֱͷ࣮ମ͸Ͳ͜ʹ͋Δͷ͔
ݴޠ࢓༷ʹؔ͢Δઆ໌͸υΩϡϝϯτΛಡΊ͹ྑ͍ͷͰ͕͢ɺ
࠷΋ਖ਼֬ͳυΩϡϝϯτ͸ԿͰ͠ΐ͏ɻ
ͦΕ͸ιʔείʔυͰ͢ɻ
ιʔείʔυͱͦΕΛઆ໌͍ͯ͠ΔυΩϡϝϯτʹࠩҟ͕͋ͬͯ΋ɺͦ
ͷιʔείʔυͰಈ͍͍ͯΔҎ্͸ιʔείʔυ͕ਖ਼֬ͳυΩϡϝϯτ
ʹͳΓ·͢ɻ
PHPͷ؇΍͔ͳൺֱΛߦ͍ͬͯΔιʔείʔυຊମΛݟͯΈ·͠ΐ͏ɻ

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؇΍͔ͳൺֱͷ࣮ମ͸Ͳ͜ʹ͋Δͷ͔
ࠓճ͸PHP8.0.9ͷιʔείʔυΛಡΜͰ͍͜͏ͱࢥ͍·͢ɻ

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ιʔείʔυͷམͱ͠ํ
·ͣ͸ී௨ʹgit clone͠·͢
git clone https://github.com/php/php-src

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ιʔείʔυͷམͱ͠ํ
ࠓͷphp-srcͷ࠷৽͸PHP8.1.4ͷRCʹͳ͍ͬͯΔͷͰɺ8.0.9ʹΞοϓ
σʔτ͞ΕͨίϛοτΛಛఆͯ͠νΣοΫΞ΢τͯ͋͛͠·͢ɻ
git checkout a5368c55be0a42af9fdc2c76fb0c2a06a42ddf36

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ʊਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓਓʊ
ʼɹPHPͷ؇΍͔ͳൺֱ͸ಈ࡞Λݫີʹઆ໌Ͱ͖Δਓ͔͠࢖ͬͯ͸͍͚·ͤΜɻɹʻ
ʉY^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^Y^
ʉ

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֘౰ιʔεʹḷΓண͘ํ๏
ϊʔώϯτͰPHPͷιʔείʔυΛಡΜͰ΋ɺ໨తͷ৔ॴʹͨͲΓண
͚ͳ͚Ε͹ҙຯ͕͋Γ·ͤΜɻ
ݴޠಛ༗ͷԋࢉࢠΛจࣈྻͰgrep΍IDEͷϑΝΠϧݕࡧΛͯ͠Έ·͢ɻ
ࠓճ͸Ӊ஦ધԋࢉࢠ(<=>)Ͱݕࡧͯ͠Έ·͢ɻ

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ͳΜ͔ͦΕͬΆ͍ϑΝΠϧ͕ݟ͔ͭΓ·ͨ͠ɻ
PHPͷԋࢉࢠΛจࣈྻͱͯ͠ఆ͍ٛͯ͠Δࠜຊ͸Zend/
zend_language_parser.yʹ͋Γͦ͏Ͱ͢ɻ
※.yͷ֦ுࢠͷϑΝΠϧ͸ߏจղੳػΛੜ੒͢ΔͨΊʹɺYaccͱݴ͏πʔ
ϧͷϑΝΠϧͷԋࢉࢠͰ͢ɻ
Zend/zend_language_parser.yΛ։͍ͯΈ·͢ɻ

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Ӊ஦ધԋࢉࢠͷ্͙͢ʹո͍͠ߦ͕͋Γ·ͨ͠ɻ
໨తͷʮ==ʯ͸T_IS_EQUALͱ͍͏໊લ͕෇͍͍ͯΔΈ͍ͨͰ͢ɻ
Zend/zend_language_parser.y಺ͰT_IS_EQUALΛݕࡧ͢Δͱ

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͜Μͳιʔε͕ݟ͔ͭΓ·͢ɻ
Ͳ͏΍ΒZEND_IS_EQUALͱ͍͏໊લͰதؒίʔυʹม׵͞ΕΔΈͨ
͍Ͱ͢ɻ

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ZEND_IS_EQUALͱݴ͏ϫʔυΛෳ਺ϑΝΠϧݕࡧ͢Δͱɺ
Zend/zend_opcode.cʹ͜Μͳߦ͕͋Γ·ͨ͠
case ZEND_IS_EQUAL:

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Zend/zend_opcode.cͷத਎
END_API binary_op_type get_binary_op(int opcode)

{

switch (opcode) {

/* ~~~~~~~~~~ */

case ZEND_IS_EQUAL:

case ZEND_CASE:

return (binary_op_type) is_equal_function;

case ZEND_IS_NOT_EQUAL:

return (binary_op_type) is_not_equal_function;

/* ~~~~~~~~~~ */

default:

ZEND_UNREACHABLE();

return (binary_op_type) NULL;

}

}
͜Μͳͷ͕͍·ͨ͠ɻ

ZEND_IS_EQUAL͸is_equal_functionͱ͍͏ؔ਺ʹରԠ͍ͯ͠ΔΑ͏Ͱ͢Ͷɻ

is_equal_functionͰݕࡧΛ͔͚ͯΈ·͢ɻ

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is_equal_functionͰݕࡧΛ͔͚ͯΈΔ
ZEND_API int ZEND_FASTCALL is_equal_function(zval *result, zval *op1, zval *op2)
Zend/zend_operators.cʹḷΓண͖·ͨ͠ɻ

ϊʔώϯτͰ΋ɺIDEͷϑΝΠϧݕࡧͰେͨ࣌ؒ͠Λ͔͚ͣʹ΄͍͠
৘ใ·ͰḷΓண͚·͢ɻ

ϥΠϒϥϦͷத਎Λௐ΂͍ͨͱ͖౳ʹ΋࢖͑ΔͷͰࢀߟʹͯ͠Έͯ͘
͍ͩ͞ɻ

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؇΍͔ͳൺֱͷਖ਼ମݟͨΓʂ
is_equal_function͸zend_compareͱݴ͏ؔ਺ʹରԠ͍ͯ͠ΔΑ͏Ͱ͢ɻ
/* == ͷॲཧ */

ZEND_API zend_result ZEND_FASTCALL is_equal_function(zval *result, zval *op1, zval *op2) /* {{{ */

{

ZVAL_BOOL(result, zend_compare(op1, op2) == 0);

return SUCCESS;

}

/* }}} */

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ZEND_API int ZEND_FASTCALL zend_compare(zval *op1, zval *op2) /* {{{ */

{

int converted = 0;

zval op1_copy, op2_copy;

while (1) {

switch (TYPE_PAIR(Z_TYPE_P(op1), Z_TYPE_P(op2))) {

case TYPE_PAIR(IS_LONG, IS_LONG):

return Z_LVAL_P(op1)>Z_LVAL_P(op2)?1:(Z_LVAL_P(op1)

/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */

case TYPE_PAIR(IS_LONG, IS_DOUBLE):

return ZEND_NORMALIZE_BOOL((double)Z_LVAL_P(op1) - Z_DVAL_P(op2));

/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */

case TYPE_PAIR(IS_ARRAY, IS_ARRAY):

return zend_compare_arrays(op1, op2);

case TYPE_PAIR(IS_NULL, IS_NULL):

/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */

case TYPE_PAIR(IS_STRING, IS_STRING):

if (Z_STR_P(op1) == Z_STR_P(op2)) {

return 0;

}

return zendi_smart_strcmp(Z_STR_P(op1), Z_STR_P(op2));

/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */

default:

if (Z_ISREF_P(op1)) {

op1 = Z_REFVAL_P(op1);

continue;

} else if (Z_ISREF_P(op2)) {

op2 = Z_REFVAL_P(op2);

continue;

}

if (Z_TYPE_P(op1) == IS_OBJECT

&& Z_TYPE_P(op2) == IS_OBJECT

&& Z_OBJ_P(op1) == Z_OBJ_P(op2)) {

return 0;

} else if (Z_TYPE_P(op1) == IS_OBJECT) {

return Z_OBJ_HANDLER_P(op1, compare)(op1, op2);

} else if (Z_TYPE_P(op2) == IS_OBJECT) {

return Z_OBJ_HANDLER_P(op2, compare)(op1, op2);

}

if (!converted) {

if (Z_TYPE_P(op1) < IS_TRUE) {

return zval_is_true(op2) ? -1 : 0;

} else if (Z_TYPE_P(op1) == IS_TRUE) {

/* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ */

} else {

op1 = _zendi_convert_scalar_to_number_silent(op1, &op1_copy);

op2 = _zendi_convert_scalar_to_number_silent(op2, &op2_copy);

if (EG(exception)) {

return 1; /* to stop comparison of arrays */

}

converted = 1;

}

} else if (Z_TYPE_P(op1)==IS_ARRAY) {

return 1;

} else if (Z_TYPE_P(op2)==IS_ARRAY) {

return -1;

} else {

ZEND_UNREACHABLE();

zend_throw_error(NULL, "Unsupported operand types");

return 1;

}

}

}

}

/* }}} */
php-src/Zend/zend_operators.c

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௕͍...
΋͏ͳΜ͔ΠϠͳ༧ײ͕͠·͢Ͷɻ
த਎Λཁ໿͍ͯ͘͠ͱɺԋࢉࢠͷࠨӈͷΦϖϥϯυͷܕͷ૊Έ߹ΘͤʹԠͯ͡ɺ
ྑ͍ײ͡ʹॲཧΛ෼ذͯ͠ฦ͍ͯ͠ΔΈ͍ͨͰ͢ɻ
਺஋ಉ࢜ͷൺֱ͸ී௨ʹߦΘΕ͍ͯ·͕͢ɺจࣈྻͷൺֱ͸ͳΜ͔ؔ਺͕ݺ͹Εͯ·͢ɻ
case TYPE_PAIR(IS_STRING, IS_STRING):

if (Z_STR_P(op1) == Z_STR_P(op2)) {

return 0;

}

return zendi_smart_strcmp(Z_STR_P(op1), Z_STR_P(op2));

zendi_smart_strcmpͱݴ͏ո͍ؔ͠਺͕ݺ͹Ε͍ͯ·͢ɻ
ͲΜͳౕ͔ݟͯΈ·͠ΐ͏ɻ

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zendi_smart_strcmpͱݴ͏ո͍ؔ͠਺
ZEND_API int ZEND_FASTCALL zendi_smart_strcmp(zend_string *s1, zend_string *s2) /* {{{ */

{

zend_uchar ret1, ret2;

int oflow1, oflow2;

zend_long lval1 = 0, lval2 = 0;

double dval1 = 0.0, dval2 = 0.0;

if ((ret1 = is_numeric_string_ex(s1->val, s1->len, &lval1, &dval1, false, &oflow1, NULL)) &&

(ret2 = is_numeric_string_ex(s2->val, s2->len, &lval2, &dval2, false, &oflow2, NULL))) {

#if ZEND_ULONG_MAX == 0xFFFFFFFF

if (oflow1 != 0 && oflow1 == oflow2 && dval1 - dval2 == 0. &&

((oflow1 == 1 && dval1 > 9007199254740991. /*0x1FFFFFFFFFFFFF*/)

|| (oflow1 == -1 && dval1 < -9007199254740991.))) {

#else

if (oflow1 != 0 && oflow1 == oflow2 && dval1 - dval2 == 0.) {

#endif

/* both values are integers overflown to the same side, and the

* double comparison may have resulted in crucial accuracy lost */

goto string_cmp;

}

if ((ret1 == IS_DOUBLE) || (ret2 == IS_DOUBLE)) {

if (ret1 != IS_DOUBLE) {

if (oflow2) {

/* 2nd operand is integer > LONG_MAX (oflow2==1) or < LONG_MIN (-1) */

return -1 * oflow2;

}

dval1 = (double) lval1;

} else if (ret2 != IS_DOUBLE) {

if (oflow1) {

return oflow1;

}

dval2 = (double) lval2;

} else if (dval1 == dval2 && !zend_finite(dval1)) {

/* Both values overflowed and have the same sign,

* so a numeric comparison would be inaccurate */

goto string_cmp;

}

dval1 = dval1 - dval2;

return ZEND_NORMALIZE_BOOL(dval1);

} else { /* they both have to be long's */

return lval1 > lval2 ? 1 : (lval1 < lval2 ? -1 : 0);

}

} else {

int strcmp_ret;

string_cmp:

strcmp_ret = zend_binary_strcmp(s1->val, s1->len, s2->val, s2->len);

return ZEND_NORMALIZE_BOOL(strcmp_ret);

}

}

/* }}} */

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zendi_smart_strcmpͱݴ͏ո͍ؔ͠਺
͏͑ʙ
ॲཧͷ಺༰͸ɺ
● ೖྗ͞Εͨจࣈྻ͕ʮ਺஋ͱͯ͠ධՁͰ͖Δ৔߹͸਺஋ͱͯ͠ѻ͍ൺֱ͢Δʯ
● ਺஋ͱͯ͠ධՁग़དྷͳ͍৔߹͸จࣈྻಉ࢜ͷൺֱΛߦ͏
strcmp໋໊ͬͯ͸ͳΜͳΜͩ...
ͭ·Γstrcmpͱ͸໊͹͔ΓͰɺจࣈྻͱͯ͠ҟͳ͍ͬͯͯ΋਺஋ͱͯ͠߹͍ͬͯΕ͹
true Ͱ͢ɻ
୭ͩ͜ΜͳΫιΈ͍ͨͳ࢓༷ࢥ͍͍ͭͨ΍ͭʙ

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͜ΕΛ౿·͑ͯ΋͏Ұ౓ίʔυΛݟͯΈ·͠ΐ͏
ιʔείʔυɿ

var_dump(0 == '00');

var_dump('00' == '0000');

var_dump('01' == '001');

ग़ྗɿ

bool(true)

bool(true)

bool(true)

͜ΕͰ๯಄ͷίʔυͷ࣮ߦ݁ՌͷṖ༹͕͚ͨͱࢥ͍·͢ɻ

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ݫີͳൺֱͷιʔε͸Ͳ͜ʁ
Zend/zend_operators.cʹ͍·͢ɻ
ZEND_API zend_bool ZEND_FASTCALL zend_is_identical(zval *op1, zval *op2) /* {{{ */

{

if (Z_TYPE_P(op1) != Z_TYPE_P(op2)) {

return 0;

}

switch (Z_TYPE_P(op1)) {

case IS_NULL:

case IS_FALSE:

case IS_TRUE:

return 1;

case IS_LONG:

return (Z_LVAL_P(op1) == Z_LVAL_P(op2));

case IS_RESOURCE:

return (Z_RES_P(op1) == Z_RES_P(op2));

case IS_DOUBLE:

return (Z_DVAL_P(op1) == Z_DVAL_P(op2));

case IS_STRING:

return zend_string_equals(Z_STR_P(op1), Z_STR_P(op2));

case IS_ARRAY:

return (Z_ARRVAL_P(op1) == Z_ARRVAL_P(op2) ||

zend_hash_compare(Z_ARRVAL_P(op1), Z_ARRVAL_P(op2), (compare_func_t)
hash_zval_identical_function, 1) == 0);

case IS_OBJECT:

return (Z_OBJ_P(op1) == Z_OBJ_P(op2));

default:

return 0;

}

}

/* }}} */

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ݫີͳൺֱͷιʔε͸Ͳ͜ʁ
·ͣ࠷ॳʹܕҧ͍ͰfalseʹͳΓ·͢ɻ
ܕ͕Ұக্ͨ͠ͰɺͦΕͧΕͷܕͰγϯϓϧͳൺֱΛ͍ͯ͠·͢ɻ
ʮ==ʯͷιʔείʔυΑΓང͔ʹγϯϓϧͰ͢ɻ

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͍͞͝ʹ
ࣗ෼΋ࠓ·ͰͳΜͱͳ͘Ͱ͔͠ɺཧղͯ͠ͳ͔ͬͨͰ͕͢ɺࠓճͷௐ
ࠪͰͲΕ͚ͩةݥͳ୅෺͔Α͘ཧղͰ͖·ͨ͠ɻ
օ͞ΜPHPͷൺֱԋࢉࢠ͸໧ͬͯݫ֨ͳൺֱΛ࢖͍·͠ΐ͏ɻ

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PHPの緩やかな比較の実態

PHPの緩やかな比較の実態

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