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zend_vm: Add OPcode specialization for === [] #18571

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Merged
merged 4 commits into from
May 19, 2025
Merged

zend_vm: Add OPcode specialization for === [] #18571

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a8d26be
zend_vm: Add OPcode specialization for `=== []`
TimWolla May 15, 2025
3597d4b
zend_vm: Add OPcode specialization for `!== []`
TimWolla May 16, 2025
b19deea
Merge branch 'master' into identical-to-empty-array
TimWolla May 19, 2025
df0e9ec
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TimWolla May 19, 2025
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1 change: 1 addition & 0 deletions UPGRADING
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Expand Up @@ -516,6 +516,7 @@ PHP 8.5 UPGRADE NOTES
- Core:
. Remove OPcodes for identity comparisons against booleans, particularly
for the match(true) pattern.
. Add OPcode specialization for `=== []` and `!== []` comparisons.

- ReflectionProperty:
. Improved performance of the following methods: getValue(), getRawValue(),
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26 changes: 26 additions & 0 deletions Zend/zend_vm_def.h
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Expand Up @@ -10062,6 +10062,32 @@ ZEND_VM_HOT_TYPE_SPEC_HANDLER(ZEND_IS_NOT_EQUAL|ZEND_IS_NOT_IDENTICAL, (op1_info
ZEND_VM_SMART_BRANCH(result, 0);
}

ZEND_VM_TYPE_SPEC_HANDLER(ZEND_IS_IDENTICAL, op->op2_type == IS_CONST && (Z_TYPE_P(RT_CONSTANT(op, op->op2)) == IS_ARRAY && zend_hash_num_elements(Z_ARR_P(RT_CONSTANT(op, op->op2))) == 0), ZEND_IS_IDENTICAL_EMPTY_ARRAY, TMPVARCV, CONST, SPEC(SMART_BRANCH,COMMUTATIVE))
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Why do I manually need to check op->op2_type == IS_CONST here? Shouldn't that be the job of the CONST in ZEND_IS_IDENTICAL_EMPTY_ARRAY, TMPVARCV, CONST?

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More generally speaking, I'm not at all sure if the “flags” I specified here are correct, since I clearly don't understand the implications. So please carefully check this 😄

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You can look at the generated zend_vm_set_opcode_handler_ex(). It assumes op types are correct. If it works only for some op types, checking the op type should be the right approach. The signature looks correct to me.

{
USE_OPLINE
zval *op1;
bool result;

op1 = GET_OP1_ZVAL_PTR_DEREF(BP_VAR_R);
result = Z_TYPE_P(op1) == IS_ARRAY && zend_hash_num_elements(Z_ARR_P(op1)) == 0;
FREE_OP1();
FREE_OP2();
ZEND_VM_SMART_BRANCH(result, 0);
}

ZEND_VM_TYPE_SPEC_HANDLER(ZEND_IS_NOT_IDENTICAL, op->op2_type == IS_CONST && (Z_TYPE_P(RT_CONSTANT(op, op->op2)) == IS_ARRAY && zend_hash_num_elements(Z_ARR_P(RT_CONSTANT(op, op->op2))) == 0), ZEND_IS_NOT_IDENTICAL_EMPTY_ARRAY, TMPVARCV, CONST, SPEC(SMART_BRANCH,COMMUTATIVE))
{
USE_OPLINE
zval *op1;
bool result;

op1 = GET_OP1_ZVAL_PTR_DEREF(BP_VAR_R);
result = Z_TYPE_P(op1) != IS_ARRAY || zend_hash_num_elements(Z_ARR_P(op1)) > 0;
FREE_OP1();
FREE_OP2();
ZEND_VM_SMART_BRANCH(result, 0);
}

ZEND_VM_TYPE_SPEC_HANDLER(ZEND_IS_IDENTICAL, op->op1_type == IS_CV && (op->op2_type & (IS_CONST|IS_CV)) && !(op1_info & (MAY_BE_UNDEF|MAY_BE_REF)) && !(op2_info & (MAY_BE_UNDEF|MAY_BE_REF)), ZEND_IS_IDENTICAL_NOTHROW, CV, CONST|CV, SPEC(COMMUTATIVE))
{
/* This is declared below the specializations for MAY_BE_LONG/MAY_BE_DOUBLE so those will be used instead if possible. */
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