php-in-php: JIT GcCollectCyclesRuntime — route gc_collect_cycles() through CycleCollector PHP not ~1.3k-line LLVM (#1492)

[PurHur]

Category

php-in-php

Problem

gc_collect_cycles() VM builtin already delegates to PHPCompiler\VM\CycleCollector from ext/standard/gc_collect_cycles.php, but JIT/AOT still links ~1280 lines of LLVM in lib/JIT/Builtin/GcCollectCyclesRuntime.php + GcCollectCyclesNative.php (__compiler_gc_collect_cycles, destructor lists, hashtable walks). GC semantics should live in PHP (lib/VM/CycleCollector.php) with a thin JIT trampoline — not a parallel native collector.

php-src reference

• Zend/zend_gc.c — cycle collection, root buffer, destructor ordering
• ext/standard/info.c — PHP_FUNCTION(gc_collect_cycles)

Repro

<?php
class Node { public ?Node $next = null; public function __destruct() { echo "dtor\n"; } }
$a = new Node; $b = new Node; $a->next = $b; $b->next = $a; unset($a, $b);
echo gc_collect_cycles(), "\n";

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

Zend: prints 2 (two nodes collected) and destructor output order per GC flags.
This compiler VM: uses CycleCollector::collect() — JIT must call the same helper.

Scope (this repo)

Area	Path	Action
VM SSOT	lib/VM/CycleCollector.php	Keep collector logic here
Stdlib	ext/standard/gc_collect_cycles.php, JitGcCollectCycles.php	JIT bridge → PHP collector
Delete/shrink	lib/JIT/Builtin/GcCollectCyclesRuntime.php, GcCollectCyclesNative.php	Remove LLVM collector
gc_status pair	lib/JIT/Builtin/GcStatusRuntime.php	Coordinate with #9150

Done when (php-src-strict)

• JIT/AOT gc_collect_cycles() invokes CycleCollector (or shared PHP helper), not LLVM hashtable walk
• GcCollectCyclesRuntime.php deleted or thin shim; PR cites lines removed from lib/JIT/Builtin/
• Repro cycle count + destructor behavior matches Zend on VM and JIT
• test/unit/GcCollectCycles*.php + compliance guards green
• No new symbols in runtime/*.c

Verification

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && vendor/bin/phpunit --filter GcCollectCycles'
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/jit.php test/compliance/cases/stdlib/gc_collect_cycles_basic.phpt'

Links

• North star Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492
• gc_status PHP migration: php-in-php: JIT GcStatusRuntime — route gc_status() through VmGcStatus PHP not LLVM hashtable builder (#1492) #9150
• gc_mem_caches parity: Stdlib: gc_mem_caches() — return value always 0 not bytes released (ext/standard/php_gc.c) #9160

[PurHur]

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

[PurHur]

Unclaiming: basic repro + GcCollectCycles unit behavior already match Zend on VM+JIT (2026-06-18). Remaining work is LLVM deletion/routing (#9269 architectural scope) — deferring to a dedicated php-in-php pass.

[PurHur]

Duplicate of #9541 (GcCollectCyclesRuntime php-in-php migration; newer issue has fuller verification scope).