php-in-php: JIT StringReadfile — route readfile() through VmFs PHP not __compiler_readfile libc LLVM (#1492)

[PurHur]

Category

php-in-php · stdlib

Problem

readfile() VM path already uses PHP (ext/standard/readfile.php → VmFs::readfile()), but JIT/AOT still calls LLVM helper __compiler_readfile implemented in lib/JIT/Builtin/StringReadfile.php with direct open/read/write libc FFI.

Workers should route JIT lowering through the same PHP semantics (ext/standard/JitReadfile.php → shared VmFs/VmFsReadNative) and delete/shrink the standalone libc LLVM body.

php-src reference

• php/php-src ext/standard/streamsfuncs.c — php_readfile / php_stream_passthru

Repro (JIT divergence)

<?php
$path = sys_get_temp_dir() . '/phpc_readfile_' . getmypid() . '.txt';
file_put_contents($path, 'abc');
$n = readfile($path);
@unlink($path);
var_export($n);
echo "\n";

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

Today VM uses PHP VmFs; JIT uses __compiler_readfile LLVM — parity issue is JIT lowering path, not missing builtin.

Scope (this repo)

Layer	Path
VM (source of truth)	ext/standard/readfile.php, ext/standard/VmFs.php
JIT today	ext/standard/JitReadfile.php, lib/JIT/Builtin/StringReadfile.php
Target	JIT calls compiled PHP/native shim shared with VM; remove libc read loop from StringReadfile.php

Pairs #8920 (VmFsReadNative / file_get_contents PHP path).

Done when

• JIT readfile() returns same byte count / false as VM on repro
• AOT agrees when readfile is in compile unit
• lib/JIT/Builtin/StringReadfile.php libc FFI removed or reduced to thin ABI trampoline
• PR body notes lines removed from LLVM/C helper vs PHP path added
• ./script/ci-fast.sh --filter Readfile (or new compliance PHPT) green

Related

• php-in-php: VmFsReadNative — pure PHP file_get_contents path without libc open/read FFI (#1492) #8920 VmFsReadNative (file_get_contents PHP-in-PHP)
• North star: Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: PHP Runtime → PHP — starting this run.

[PurHur]

Merged via #10698

What changed: __compiler_readfile JIT/AOT now links a thin LLVM bridge to compiled ReadfileJitHelper::readfile() (delegates to VmFs::readfile()). Deleted ~125 lines of libc open/read/write LLVM from StringReadfile.php.

Verification (green):

vendor/bin/phpunit test/unit/ReadfileRuntimeShrinkTest.php test/unit/JIT/ReadfileRuntimeStandaloneTest.php
# OK (4 tests, 12 assertions)

php bin/vm.php test/compliance/cases/stdlib/readfile.phpt
php bin/jit.php test/compliance/cases/stdlib/readfile.phpt
# hello readfile / 15 / false

make bootstrap-selfhost-vm-driver-execute-probe
# OK