Regression: restore standalone AOT GC LLVM cycle scan (#18630)

[PurHur]

Summary

Fixes a master regression introduced by #18640 (#18630): nested-JIT of GcCollectCyclesNativeScanJitHelper during standalone AOT init produced invalid LLVM IR (__value__writeHashtable type mismatch), breaking all bin/compile.php standalone builds including HelloWorld, hash, and password_hash AOT fixtures.

Root cause: #18640 set usesPhpRegistry() always true and routed standalone phpc_gc_collect_cycles_impl through PHP array scan helpers; nested JIT of those helpers fails module verify.

Fix: Restore pre-#18640 dual path — embed uses PHP registry (GcCollectCyclesRegistryJitHelper); standalone uses GcCollectCyclesStandaloneLlvm for cycle scan/registry LLVM (same as #17015). Keeps #18630 PHP-in-PHP goal for embed; defers standalone PHP scan until nested array JIT is safe.

php-src reference

• Zend/zend_gc.c — gc_collect_cycles / root buffer

Verification

source script/php-env.sh

# HelloWorld AOT (was Module verification failed)
./vendor/bin/phpunit --filter ExamplesHelloWorldAotRegressionTest
# OK (4 tests, 22 assertions)

# GC standalone ABI
./vendor/bin/phpunit --filter 'GcCollectCyclesRuntimeStandaloneTest|GcCollectCyclesStandaloneLlvmShrinkTest'
# OK

# Simple compile
tmpdir=$(mktemp -d)
php bin/compile.php -o "$tmpdir/h" -r 'echo "hello\n";' && "$tmpdir/h"
# hello

# Hash incremental VM + AOT
php bin/vm.php test/repro/hash_context_incremental.php
# b94d27b9… ×2
export PHP_COMPILER_AOT_USER_SCRIPT=1
php bin/compile.php -o "$tmpdir/hc" test/repro/hash_context_incremental.php && "$tmpdir/hc"
# b94d27b9… ×2

export PHP_COMPILER_AOT_USER_SCRIPT=1
php bin/compile.php -o "$tmpdir/h" -r 'echo hash("sha256","hello"),"\n";' && "$tmpdir/h"
# 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824

Closes #18630 (regression follow-up — full standalone PHP GC scan remains future work)

Made with Cursor

[PurHur]

Merged spine follow-up #18735 — added GcCollectCyclesStandaloneLlvm.php to compiler_lib_spine_smoke/main.php; check-selfhost-spine-coverage-sync OK (4794/4794).