php-in-php: drop always-on LibcExtern strchr+strstr after NestedJIT module-local decls (#31458 shape)

[PurHur]

Category

php-in-php · runtime-shrink (#1492, peer #31458 / #31498 / #31403)

Problem

User-script strchr()/strstr() already route through PHP (VmString::strstr / StrstrJitHelper) — PHP strchr is an alias of strstr, not libc. Always-on LibcExtern still registers libc strchr and dead libc strstr for every compile.

Path	Today	Target
User-script AOT strchr()/strstr()	VmString::strstr / helpers (already)	unchanged
LibcExtern	always-on strchr + strstr	drop both rows
NestedJIT putenv leaf (StringGetenv)	lookupFunction('strchr') via always-on	ensureLibcStrchr module-local
NestedJIT JitParseStrUserScriptCstrKernel	already declares strchr in ensureLibc	unchanged
libc strstr	no lookupFunction consumers	delete dead always-on

php-src reference

• php/php-src ext/standard/string.c — PHP_FUNCTION(strstr) / strchr alias (semantics stay in PHP; libc strchr is NestedJIT putenv/parse_str thin ABI only)

PHP implementation target

• lib/JIT/LibcExtern.php — drop strchr + strstr rows; cite this issue
• lib/JIT/Builtin/StringGetenv.php — ensureLibcStrchr before NestedJIT putenv strchr lookup
• ext/standard/JitParseStrUserScriptCstrKernel.php — keep existing module-local strchr in ensureLibc
• test/unit/LibcExternDeadDeclsRuntimeShrinkTest.php — guard the drop

Repro

./script/phpunit.sh --filter LibcExternDeadDeclsRuntimeShrinkTest
./script/phpunit.sh --filter 'StringGetenv|ParseStr|Strstr'

Done when

• strchr and strstr absent from LibcExtern specs
• StringGetenv::invokePutenvNestedLeaf declares strchr module-locally
• Shrink unit tests green; putenv NestedJIT path still links
• PR body cites LOC removed from always-on surface

Refs #1492, #31458, #31498, #31403

[PurHur]

claim: PHP Runtime → PHP — starting this run

Dropping always-on LibcExtern strchr+strstr (#31458/#31498 shape). NestedJIT putenv leaf gets module-local ensureLibcStrchr; JitParseStrUserScriptCstrKernel already declares strchr locally.

[PurHur]

Merged via #31523

Verification:

• ./script/phpunit.sh --filter 'LibcExternDeadDeclsRuntimeShrinkTest|ModuleAlwaysOnFsDeclsRuntimeShrinkTest' → OK (7 tests, 106 assertions)
• php script/bootstrap-inventory.php --check → OK 7552/7552
• AOT putenv NestedJIT strchr leaf (PHPC_STRCHR_31519=ok) → ok

C surface removed: LibcExtern always-on strchr + dead strstr rows (2 symbols). NestedJIT keeps module-local strchr in StringGetenv::ensureLibcStrchr + existing JitParseStrUserScriptCstrKernel::ensureLibc. No new C runtime.

Not covered: full ci-local.sh; AOT getenv_local_only fixture already fails on master (same symptom).