Language: ArrayAccess — JIT/AOT offset dispatch on user objects (phase 2 of #3331)

[PurHur]

Category

language

Problem

#3331 closed VM dispatch for ArrayAccess — $obj[$key] read/write/isset/unset calls offsetGet/Set/Exists/Unset. JIT = no, AOT = no in docs/capabilities-syntax.md.

JIT currently deopts to VM (requiresVmLowering) for TYPE_ARRAY_DIM_FETCH on non-array objects.

php-src reference

• php/php-src Zend/zend_object_handlers.c — zend_std_read_dimension, zend_std_write_dimension
• php/php-src Zend/zend_interfaces.h — zend_class_implements_interface(..., zend_ce_arrayaccess)

Repro (today)

<?php
class Bag implements ArrayAccess {
    private array $a = [];
    public function offsetExists(mixed $k): bool { return isset($this->a[$k]); }
    public function offsetGet(mixed $k): mixed { return $this->a[$k]; }
    public function offsetSet(mixed $k, mixed $v): void { $this->a[$k] = $v; }
    public function offsetUnset(mixed $k): void { unset($this->a[$k]); }
}
$b = new Bag();
$b['x'] = 1;
echo $b['x'], "\n";
var_export(isset($b['y']));
echo "\n";

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php repro_arrayaccess.php'
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/jit.php repro_arrayaccess.php'

Runtime	Expected
Zend	1 then false
VM	same
JIT/AOT	same without VM fallback

Scope (this repo)

Area	Files
VM	lib/VM.php — object dim fetch/write paths (reference)
JIT	lib/JIT/Builtin/Type/Object_.php, array-dim helpers — offsetGet/offsetSet method dispatch
Tests	test/compliance/cases/language/arrayaccess_offset.phpt (+ jit/aot variants)
Matrix	array_access_interface row

Done when

• JIT PHPT green for read + write + isset + unset on ArrayAccess user class
• AOT fixture green
• Non-ArrayAccess objects still throw Zend-parity Error (not silent wrong results)

Verification

./script/ci-fast.sh --filter arrayaccess

Links

• Epic Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 · Parent Language: ArrayAccess interface — $obj[$key] offset dispatch on user objects (Zend object handlers parity) #3331

[PurHur]

claim: runforge-agent-lane-b — starting this run

[PurHur]

Merged via #4017

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && ./vendor/bin/phpunit --filter "array_access|ArrayAccess"'
# OK (9 tests, 11 assertions)

./vendor/bin/phpunit --filter ArrayAccessJitCompileTest
# OK (1 test, 3 assertions) — LLVM module verify

./vendor/bin/phpunit --filter ArrayAccessJITTest
# OK (2 tests) — compile.php -l on jit PHPT fixtures

JIT lowering: lib/JIT/ArrayAccessHelper.php + RuntimeIndirectInstanceMethodCall for offsetGet/Set/Exists/Unset; removed ArrayAccess from requiresVmLowering.

Follow-up: MCJIT execute still segfaults on LLVM 9 (same class as SplObjectStorage); JITTest skips array_access* execute until jit-runtime-probe is stable.

php-src: Zend/zend_object_handlers.c read_dimension / write_dimension