php-in-php: JIT InstanceOfHelper — route instanceof through VmTypeCheck PHP not ~217-line LLVM (#1492)

[PurHur]

Category

php-in-php · compile pipeline · refs #1492

Problem

JIT instanceof lowering lives in lib/JIT/InstanceOfHelper.php (~217 lines) emitting bespoke LLVM for literal class names, dynamic RHS types, enum/interface checks, and invalid-RHS errors. VM already resolves instanceof via lib/VM/TypeCheck.php + InterfaceCheck — duplicate semantics in LLVM.

Risk: JIT/AOT disagree with VM on edge cases (#4339, enum units, __Stringable, trait aliases) unless every branch is mirrored twice.

php-src reference (semantics)

• php/php-src Zend/zend_execute.c — instanceof_function_slow
• php/php-src Zend/zend_interfaces.c — interface/instanceof tables

Repro (parity drift today)

test/repro/instanceof_jit_vm_agree.php:

<?php
declare(strict_types=1);

interface I {}
enum E: string { case A = 'x'; }
class C implements I {}

$checks = [
    new C() instanceof I::class,
    E::A instanceof E::class,
    's' instanceof \Stringable::class,
];
foreach ($checks as $i => $v) {
    echo "$i=" . ($v ? '1' : '0') . "\n";
}

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php bin/vm.php test/repro/instanceof_jit_vm_agree.php
php bin/jit.php test/repro/instanceof_jit_vm_agree.php'

Audit any JIT-only divergence vs VM; after migration both backends must match.

Scope (PHP-in-PHP first)

Path	Work
lib/VM/TypeCheck.php / new VmInstanceOf.php	Single PHP entry for literal + dynamic RHS
lib/JIT/InstanceOfHelper.php	Shrink to trampoline → compiled PHP helper (or delete branches)
lib/JIT/Builtin/Type/Object_.php	Stop duplicating instanceof tables in LLVM where possible
Tests	Extend test/compliance/cases/language/instanceof*.phpt with JIT guard

Done means lines removed from InstanceOfHelper.php / Object_.php LLVM, not a second copy of zend tables in C.

Done when

• Repro byte-identical on VM + JIT + AOT (where instanceof is JIT-supported)
• Invalid RHS (array/int) throws TypeError with Zend message via shared PHP helper
• InstanceOfHelper.php ≤ ~80 lines (trampoline + type dispatch only)
• ./script/ci-fast.sh --filter instanceof green

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter InstanceOf'

Related

• Language: instanceof with dynamic class name — TypeError for non-string operand (zend_execute.c parity) #4339 instanceof baseline · php-in-php: JIT CastHelper — route (array)/(object)/(unset) casts through VmCast PHP not ~495-line LLVM (#1492) #10046 CastHelper migration (parallel pattern) · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

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

[PurHur]

Merged via #10609.

Verification

• ./vendor/bin/phpunit --filter InstanceOfRuntimeShrinkTest — OK (4 tests)
• ./vendor/bin/phpunit --filter "JITTest::testCases.*instanceof_class_jit|JITTest::testCases.*instanceof_enum" — OK (5 tests)
• make bootstrap-selfhost-vm-driver-execute-probe — OK

Dynamic RHS type guards now live in lib/VM/InstanceOfJitHelper.php; InstanceOfHelper uses JitVmHelperLink for value-box dispatch.