php-in-php: JIT SessionEncodeRuntime — route session_encode()/session_decode() through VmSession PHP not ~530-line LLVM (#1492)

[PurHur]

Category

php-in-php — session serializer LLVM → ext/session PHP

Problem

lib/JIT/Builtin/SessionEncodeRuntime.php (~530 lines) lowers session_encode() / session_decode() into bespoke LLVM (php_session_encode / decode paths). VM session logic already lives in ext/session/ PHP modules; JIT should call the same PHP implementations via trampoline, not duplicate serializer state machines in LLVM.

Pairs with #9411 (SessionGcRuntime → VmSession PHP) and #9360 (PendingHeadersRuntime).

php-src reference

• ext/session/session.c — php_session_encode() / php_session_decode()
• ext/standard/basic_functions.c — session_encode / session_decode userland wrappers

Repro

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && php bin/vm.php -r '"'"'session_start(); $_SESSION["k"]="v"; echo session_encode();'"'"''

Today JIT path may diverge or require SessionEncodeRuntime::ensureLinked() LLVM. After migration, bin/jit.php with same snippet must match VM output byte-for-byte.

Scope

• ext/session/ — expose VmSession::encode() / decode() SSOT if not already callable from JIT
• lib/JIT/Builtin/SessionEncodeRuntime.php — replace LLVM bodies with PHP trampoline (JitSessionEncode.php)
• Shrink/delete LLVM serializer tables; note line count in PR
• Session GC/lifecycle remain separate issues (php-in-php: JIT SessionGcRuntime — route session_gc() through VmSession PHP not LLVM file scan (#1492) #9411, Stdlib: session_name() must refuse rename after headers sent — returns false + warning (ext/session/session.c) #9376)

Done when

• VM + JIT + AOT session_encode() / session_decode() share one PHP implementation.
• Compliance session encode/decode PHPTs green (add session_encode_roundtrip.phpt if missing).
• PR cites lines removed from SessionEncodeRuntime.php.
• No new C in runtime/ for session serialization.

Related

#1492, #9411, #9376, #9360.

[PurHur]

claim: PHP Runtime → PHP — batch (issues #9440, #9910)

[PurHur]

Merged via #11074.

LLVM shrink: SessionEncodeRuntime.php 530→304 lines; wire encode/decode loops removed.

PHP path: SessionEncodeJitHelper → VmSessionSerializer + SerializeJitHelper.

Verification: SessionEncodeRuntimeShrinkTest + session_encode compliance (6 VM+JIT cases) + VM/JIT repro byte-identical.