php-in-php: JIT ObOutputRuntime — route ob_* stack through VmObOutput PHP not ~1k-line LLVM (#1492)

[PurHur]

Category

php-in-php

Problem

Output buffering (ob_start, ob_get_contents, ob_end_flush, implicit flush, echo into active buffer) is implemented twice: VM uses ext/standard/VmOb.php / VmObOutput.php, while JIT/AOT embeds ~1050 lines of LLVM stack management in lib/JIT/Builtin/ObOutputRuntime.php (__phpc_ob_* globals, libc fwrite, buffer caps). This is classic PHP-in-PHP debt — behavior belongs in ext/standard, not a second C-like runtime in LLVM IR.

php-src reference

• ext/standard/output.c — php_ob_* stack, handlers, flush
• main/output.c — SAPI output layer interaction

Repro (VM vs JIT must match)

<?php
ob_start();
echo 'hello';
$buf = ob_get_contents();
ob_end_clean();
var_dump($buf);
echo ob_get_level(), "\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: string(5) "hello", level 0.
Done when: identical on VM and JIT/AOT after migration.

Nested buffers + ob_implicit_flush smoke:

<?php
ob_start(); ob_start(); echo 'x'; var_dump(ob_get_level()); ob_end_flush(); ob_end_flush();

Scope (this repo)

Area	Path	Action
Stdlib SSOT	ext/standard/VmOb.php, VmObOutput.php, ob_*.php	Single ob stack implementation
JIT bridge	ext/standard/JitOb*.php (extend)	Route JIT calls to PHP helpers
Delete/shrink	lib/JIT/Builtin/ObOutputRuntime.php, ObOutput.php	Remove LLVM ob stack
Echo lowering	lib/JIT.php ob echo paths	Call PHP bridge instead of __phpc_ob_echo_*
Related	lib/JIT/Builtin/ObGzhandlerJitRuntime.php	Pairs with #9091 (handler callback)

Do not reintroduce lib/AOT/runtime/phpc_ob.c logic — shrink C, grow PHP.

Done when (php-src-strict)

• JIT/AOT ob stack uses the same PHP state machine as VM (VmObOutput)
• ObOutputRuntime.php deleted or <50-line ABI shim; PR cites lines removed
• Repro scripts match Zend on VM + JIT + AOT
• Existing ob_* compliance PHPTs green on JIT/AOT
• make bootstrap-selfhost-vm-driver-execute-probe still green if echo/ob touched on spine

Verification

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

Links

• North star Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492
• ob_gzhandler PHP path: php-in-php: JIT __compiler_ob_gzhandler — route ob_gzhandler through VmZlib PHP not C zlib FFI (#1492) #9091

[PurHur]

claim: PHP Runtime → PHP — batch (issues #9268)

[PurHur]

Merged via #11706.

LLVM shrink: ObOutputRuntime.php 1087→28 lines (JIT/embed delegates to ObOutputJitBridge + ObOutputJitHelper PHP). Standalone AOT LLVM quarantined in ObOutputStandaloneLlvm.php.

Verification:

php bin/vm.php / php bin/jit.php ob_start repro → string(5) "hello", level 0
vendor/bin/phpunit test/unit/ObOutputRuntimeShrinkTest.php → OK (3 tests)
vendor/bin/phpunit test/unit/JIT/ObOutputRuntimeStandaloneTest.php → OK
make bootstrap-selfhost-vm-driver-execute-probe → OK