php-in-php: drop always-on LibcExtern strtod after NestedJIT module-local (#31988 shape)

[PurHur]

Category

php-in-php · runtime-shrink (#1492, peer #31988 strtol / #31971 strcmp)

Problem

Always-on LibcExtern still registers libc strtod(3) even though:

1. User-script floatval() / doubleval() / is_numeric() already live in ext/standard PHP (string-to-float parse uses libc strtod only as a NestedJIT trampoline, not as a user-visible builtin).
2. ~12 NestedJIT leaves call lookupFunction('strtod') for compile-time numeric parse (scalar cast, filter tokens, min/max, array_unique, typed params, web params) — they rely on the always-on row.
3. ext/standard/Module.php jitInit still always-declares strtod as a fallback — that path should drop with the LibcExtern row (peer php-in-php: drop always-on LibcExtern strtol after NestedJIT module-local (#31971 shape) #31988 strtol).

Path	Today	Target
User-script floatval()/is_numeric()	ext/standard PHP	unchanged
LibcExtern	always-on strtod row	drop row
NestedJIT consumers	rely on always-on	LibcExtern::ensureStrtodDecl() before lookup
Module::jitInit	always-on strtod fallback	drop; comment peer #31988

php-src reference

• Userland: php/php-src Zend/zend_operators.c — is_numeric_string / zend_strtod
• php/php-src ext/standard/type.c — PHP_FUNCTION(floatval)

PHP implementation target

• lib/JIT/LibcExtern.php — drop 'strtod' always-on row; add ensureStrtodDecl()
• NestedJIT consumers call LibcExtern::ensureStrtodDecl() before lookupFunction('strtod')
• ext/standard/Module.php — drop always-on strtod jitInit fallback
• test/unit/LibcExternDeadDeclsRuntimeShrinkTest.php + StrtodRuntimeShrinkTest — assert row gone + consumer wiring

Repro

./script/phpunit.sh --filter LibcExternDeadDeclsRuntimeShrinkTest
./script/phpunit.sh --filter StrtodRuntimeShrinkTest

Done when

• LibcExtern has no always-on 'strtod' => row
• All NestedJIT lookupFunction('strtod') sites call ensureStrtodDecl() first
• LibcExternDeadDeclsRuntimeShrinkTest + shrink guard green
• php-src-strict; user-script floatval()/is_numeric() behavior unchanged

[PurHur]

claim: PHP Runtime → PHP — starting this run

Drop always-on LibcExtern strtod after NestedJIT module-local ensureStrtodDecl (#31988 shape).

[PurHur]

Merged in #31998 (f26b7a2461).

Always-on LibcExtern/Module strtod(3) dropped; NestedJIT leaves call ensureStrtodDecl() before lookup. User-script floatval()/is_numeric() unchanged.

Verification:

./script/phpunit.sh --filter 'LibcExternDeadDeclsRuntimeShrinkTest|StrtodRuntimeShrinkTest|LibcExternMathRuntimeShrinkTest'
OK (32 tests, 549 assertions)

VM smoke: floatval('3.14') → 3.14, is_numeric('2.5') → yes, (float)'1e2' → 100.

C runtime: no runtime/*.c added; always-on LLVM extern row + Module jitInit fallback removed.