php-in-php: JIT ExceptionThrowRuntime — route throw/Object throw through VmException PHP not LLVM unwind (#1492)

[PurHur]

Category

php-in-php · compile/runtime bridge

Problem

lib/JIT/Builtin/ExceptionThrowRuntime.php (~349 lines) implements throw/unwind setup in LLVM (exception object globals, bridge to ExceptionJitHelper). VM throw semantics live in lib/VM.php + VmException paths; JIT duplicates unwind tables instead of reusing compiled PHP helpers.

Sibling #9663 tracks ExceptionHandlerJitRuntime + try/catch; this issue is the throw expression / Object.throw fast path only.

php-src reference

• php/php-src Zend/zend_exceptions.c — zend_throw_exception_internal, zend_throw_error
• php/php-src Zend/zend_vm_execute.h — ZEND_HANDLE_EXCEPTION

Repro

<?php
try {
    throw new RuntimeException('probe');
} catch (RuntimeException $e) {
    echo $e->getMessage(), "\n";
}

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

VM prints probe; JIT must match without growing ExceptionThrowRuntime LLVM.

Scope (this repo)

Piece	Path
PHP SSOT	lib/VM/VmException.php (or extract throw helper used by VM + JIT)
JIT	ExceptionThrowRuntime::implement() → emit call into ExceptionThrowJitHelper compiled unit
Shrink	delete LLVM throw object materialization from ExceptionThrowRuntime.php
Tests	existing test/compliance/cases/language/throw_*.phpt, test/unit/JitExceptionTest.php

No new runtime/*.c exception tables.

Done when

• JIT throw path calls compiled PHP helper; repro matches VM
• ExceptionThrowRuntime LLVM implement() removed or ≤50-line trampoline
• PR body cites php-src paths + lines removed from LLVM runtime
• ./script/ci-fast.sh --filter throw green on JIT fixtures

Verification

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

Related

• php-in-php: JIT ExceptionHandlerJitRuntime + TryCatchHelper — route try/catch through VmException PHP not ~1.5k-line LLVM (#1492) #9663 (try/catch handler) · php-in-php: JIT TryCatchHelper — route try/catch/throw dispatch through VmException PHP not ~880-line LLVM (#1492) #9632 (ExceptionJitHelper) · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: PHP Runtime → PHP — starting this run.

[PurHur]

Merged via #10802.

What changed: JIT embed and AOT standalone both route phpc_jit_* throw/catch pending state through ExceptionJitHelper PHP. Deleted JitThrow LLVM globals path (phpc_jit_throw_flag, implementPendingHelpers). ExceptionThrowRuntime.php shrunk 349→63 lines via shared JitHelperAbiBridge.

Verification:

• vendor/bin/phpunit --filter ExceptionThrowRuntimeShrinkTest — OK (3 tests)
• exception_throw_caught.phpt, throw_expression.phpt, exception_throw_catch_finally.phpt — VM + JIT OK
• make bootstrap-selfhost-vm-driver-execute-probe — OK

php-src ref: Zend/zend_exceptions.c