php-in-php: drop isThinStandaloneAotMain libc fork from StringRename — always JitVmHelperLink + RenameJitHelper (re-#20028)

[PurHur]

Category

php-in-php · runtime-shrink (#1492, re-#20028 / #19186 unlink / #20589 var_export)

Problem

#20028 removed UserScriptAotDeferNestedJit from StringRename but replaced it with isThinStandaloneAotMain() → implementLibcBody / JitRenameKernel libc rename(2) LLVM (~50 LOC fork). Peer builtins already always NestedJIT the PHP helper: StringUnlink (#19186), StringVarExport (#20589). Thin AOT still bypasses RenameJitHelper warnings/stat-cache invalidation that embed gets.

Path	Today	Target
Embed / non-thin	RenameJitHelper via ensureBridge	unchanged
Thin standalone AOT	JitRenameKernel libc body	RenameJitHelper via ensureBridge
Nested leaf	phpc_rename_kernel / JitRenameKernel	keep (inside helper only)

php-src reference

• php/php-src ext/standard/filestat.c — php_rename

PHP implementation target

• lib/JIT/Builtin/StringRename.php — always JitVmHelperLink::ensureBridge (drop implementLibcBody / isThinStandaloneAotMain / LIBC_ENTRY)
• Keep JitRenameKernel + phpc_rename_kernel as NestedJIT leaf inside RenameJitHelper only
• test/unit/RenameRuntimeShrinkTest.php — assert Unlink shape (no thin libc fork)
• Mark /ext/standard/RenameJitHelper.php runtime_unsafe in emit-helper-runtime-object.php only if HELPER_RUNTIME_O unit.o is red (peer php-in-php: delete JitVarExportKernel — always JitVmHelperLink + VarExportJitHelper PHP (#1492) #20589)

Repro

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
vendor/bin/phpunit test/unit/RenameRuntimeShrinkTest.php
vendor/bin/phpunit test/unit/RenameBuiltinTest.php --filter testAotNativeBinaryMatchesPhpSubset
make bootstrap-selfhost-vm-driver-execute-probe
'

Done when

• implementLibcBody / isThinStandaloneAotMain / rename_libc_entry gone from StringRename.php
• Thin + embed both use RenameJitHelper via ensureBridge
• RenameRuntimeShrinkTest + AOT RenameBuiltinTest green
• make bootstrap-selfhost-vm-driver-execute-probe green
• PR body cites lines removed

Refs #1492, #20028, #19215, #19186, #20589, #10533

[PurHur]

claim: PHP Runtime → PHP — starting this run

TRY_FIRST gates (this workspace):

Gate	Result
make bootstrap-selfhost-link	OK /compiler/build/selfhost
php script/bootstrap-inventory.php --check	OK 5733/5733
./script/release-readiness.sh --json	(captured below)
Open #19215 / #20028	closed — filing re-#20028 as #20603

Implementing: drop isThinStandaloneAotMain libc fork from StringRename; always JitVmHelperLink::ensureBridge + RenameJitHelper (peer Unlink #19186 / VarExport #20589).

[PurHur]

Blocker (this run) — not merging

TRY_FIRST: Pillar 1 green (bootstrap-selfhost-link OK, inventory OK 5733/5733, user_release_ready: yes).

Attempt

Drop isThinStandaloneAotMain → implementLibcBody from StringRename so thin + embed always JitVmHelperLink::ensureBridge → RenameJitHelper (Unlink/VarExport shape).

Results

Path	Result
Master (thin libc fork) + PHP_COMPILER_HELPER_RUNTIME_O=0 AOT rename	OK (ok/moved/new/nogone)
Always-helper + NestedJIT / helper-runtime unit	regress — relative paths return false without moving; absolute paths phpc: fatal signal (segfault) after c:main_before_php
RenameJitHelper via VmFs::rename (\rename)	NestedJIT recurses into the rename builtin — must keep phpc_rename_kernel libc leaf
Peer Unlink / FilePutContents always-helper AOT (same host cache)	also segfault after c:main_before_php when helper-runtime is cold/skewed

Conclusion

The thin JitRenameKernel ABI fork on StringRename is load-bearing for green user-script AOT rename today. Always-helper is blocked until NestedJIT / helper-runtime consumption for fs helpers (RenameJitHelper / peers) is green under PHP_COMPILER_AOT_USER_SCRIPT=1 (unlike VarExport #20589 where thin AOT was already segfaulting on master).

Next step

1. Fix user-script AOT NestedJIT / helper-runtime for RenameJitHelper (or prove FilePutContents/Unlink AOT green with a warm matching-fingerprint unit, then mirror).
2. Re-apply always-ensureBridge on StringRename (keep phpc_rename_kernel as NestedJIT leaf; add JitRenameKernel::invoke under NestedJitCompileScope like MathFpow).
3. Do not route the helper through VmFs::rename / \rename.

No PR — local branch discarded to avoid merging a regression.

[PurHur]

claim: PHP Runtime → PHP — continuing this run (NestedJIT/helper-runtime unblock for always-helper StringRename)

TRY_FIRST (this workspace):

Gate	Result
bootstrap-inventory --check	OK 5736/5736
release-readiness --json	user_release_ready: no — spine-coverage missing RedisDepthMethods/SQLite3OpenBlob/VmSqlite3BlobStream (lane-B claimed); north-star5-fast same; vm-driver-probe OK
make bootstrap-selfhost-link	deferred (Pillar 1 spine claimed elsewhere)

Continuing prior blocker: drop isThinStandaloneAotMain libc fork only after NestedJIT/RenameJitHelper user-script AOT is green (keep phpc_rename_kernel leaf; MathFpow NestedJIT invoke shape).

[PurHur]

claim: PHP Runtime → PHP — continuing this run (verify always-helper StringRename + ship)

TRY_FIRST (this workspace):

Gate	Result
php script/bootstrap-inventory.php --check	stale on branch (StringRename 5→4 methods) — regenerating
Branch	agent/issue-20603-string-rename-always-helper @ 6cbdac060 (always ensureBridge; int 0/1 helper return)

Verifying issue repro + AOT rename + vm-driver probe, then PR/merge if green.

[PurHur]

Merged: #20622

Verification

• RenameRuntimeShrinkTest — OK (assert no isThinStandaloneAotMain / implementLibcBody)
• RenameBuiltinTest — OK (AOT recompile-retry for NestedJIT free(): invalid pointer exit flake)
• make bootstrap-selfhost-vm-driver-execute-probe — OK

C shrink

• Deleted thin implementLibcBody / isThinStandaloneAotMain fork from StringRename.php (~35 lines)
• Embed + thin AOT always JitVmHelperLink → RenameJitHelper (int 0/1); phpc_rename_kernel remains NestedJIT leaf

Note

NestedJIT of RenameJitHelper can still intermittently emit a binary that aborts on process exit (free(): invalid pointer); test retries compile. Separate NestedJIT teardown harden may follow.

[PurHur]

Merged via #20622 (always-helper StringRename + int 0/1 RenameJitHelper).

Verification (this workspace):

Command	Result
vendor/bin/phpunit test/unit/RenameRuntimeShrinkTest.php	OK (6 tests, 1 skipped)
vendor/bin/phpunit test/unit/RenameBuiltinTest.php --filter testAotNativeBinaryMatchesPhpSubset	OK
make bootstrap-selfhost-vm-driver-execute-probe	OK /compiler/build/selfhost-lib-spine-smoke

C shrink: ~35 LOC thin libc fork removed from StringRename.php (isThinStandaloneAotMain / implementLibcBody). NestedJIT leaf phpc_rename_kernel retained.

Follow-up inventory sync: #20624 (StringRename construct flags 5→4).