php-in-php: drop always-on LibcExtern open/close/read/write after NestedJIT declares module-locally (#31764 shape)

[PurHur]

Category

php-in-php · runtime-shrink (#1492, peer #31764 / #31606 / #31706)

Problem

Always-on LibcExtern still registers libc open/close/read/write even though:

1. User-script file/stream I/O already routes through PHP (StreamIoJitHelper / FileGetContentsJitHelper / __compiler_* — not raw libc fd ops as the PHP builtin ABI).
2. Several NestedJIT leaves already declare the symbols they need module-locally (TouchLibcRuntime, JitStreamIoKernel::ensureLibc close, JitTempnamKernel, ObStorageLlvm write); the rest only need a shared ensurePosixFd() before lookup (peer ensureStdioFile php-in-php: drop always-on LibcExtern fopen/fread/fwrite/fclose after stream kernels declare module-locally (#31606 shape) #31764).

Symbol	NestedJIT lookupFunction consumers (sample)	Already module-local
open	SessionStorage, FileGetContentsLibc, ReadfileLibc, RandomBytes, Gethostname, TouchLibc	TouchLibc
close	same + StreamIoKernel, TempnamKernel	TouchLibc, StreamIo, Tempnam
read	SessionStorage, FileGetContentsLibc, ReadfileLibc, RandomBytes, Gethostname, SocketPairIo	—
write	SessionStorage, ReadfileLibc, ObStorage, ObWriteStdout, ProgressNote, EmbedObEcho, SocketPairIo	ObStorage

Path	Today	Target
User-script fopen/file_get_contents/readfile/…	PHP helpers / __compiler_*	unchanged
LibcExtern	always-on open/close/read/write	drop rows
NestedJIT fd leaves	rely on always-on (or local ensure)	LibcExtern::ensurePosixFd() + existing local ensures

php-src reference

• php/php-src ext/standard/file.c — stream/file builtins (user-script semantics stay in PHP)
• NestedJIT uses libc open/read/write/close only as thin platform ABI trampolines inside NestedJIT leaves

PHP implementation target

• lib/JIT/LibcExtern.php — drop always-on rows; add ensurePosixFd()
• NestedJIT consumers that still rely on always-on — call ensurePosixFd before lookup
• test/unit/LibcExternDeadDeclsRuntimeShrinkTest.php (+ targeted shrink guards)
• test/repro/issue_<n>_posix_fd.php — file_get_contents / echo smoke

Repro / verify

./script/phpunit.sh --filter 'LibcExternDeadDeclsRuntimeShrinkTest|LibcNameCollisionRuntimeShrinkTest'
./script/docker-exec.sh -- bash -lc 'php bin/vm.php test/repro/issue_NNNN_posix_fd.php'
./script/docker-exec.sh -- bash -lc 'php bin/jit.php test/repro/issue_NNNN_posix_fd.php'

Done when

• LibcExtern has no 'open'|'close'|'read'|'write' => always-on rows
• NestedJIT consumers declare via ensurePosixFd or existing module-local ensure before lookup
• User-script file I/O / echo still matches Zend via VM/JIT
• No new lib/AOT/runtime/*.c
• php-src-strict; no php-compiler-strict shortcut

Note

#10533 comments are locked (2500+); candidate recorded here instead of a tracker comment.

[PurHur]

claim: PHP Runtime → PHP — starting this run

Drop always-on LibcExtern open/close/read/write after NestedJIT leaves route via LibcExtern::ensurePosixFd (#31764 shape). Branch: agent/runtime-php-posix-fd-libc-extern.

[PurHur]

Merged in #31822

Dropped always-on LibcExtern libc open/close/read/write. NestedJIT fd leaves declare them module-locally via LibcExtern::ensurePosixFd() (or existing local ensure). User-script file I/O unchanged (PHP helpers / __compiler_*). No new C.

Verification:

• ./script/phpunit.sh --filter 'LibcExternDeadDeclsRuntimeShrinkTest|LibcNameCollisionRuntimeShrinkTest' → OK (22 tests, 305 assertions)
• Related file/stream shrink filters → OK (39 tests)
• php bin/vm.php / php bin/jit.php test/repro/issue_31817_posix_fd.php → ab / ok