php-in-php: JIT StringSimilarTextJit — route similar_text() through VmString PHP not ~420-line LLVM (#1492)

[PurHur]

Category

php-in-php | stdlib

Problem

similar_text() has a PHP VM implementation (ext/standard/similar_text.php, VmString::similarText), but JIT/AOT standalone still lowers through lib/JIT/Builtin/StringSimilarTextJit.php (~420 lines of hand-written LLVM). This duplicates logic already expressible in PHP and blocks self-host shrinking of emit-helper C/LLVM tables.

php-src reference

• php/php-src ext/standard/string.c — php_similar_text()
• Reference PHP path: ext/standard/similar_text.php in this repo

Repro (LLVM path active today)

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php bin/vm.php -r "echo similar_text(\"hello\", \"hallo\", \$p), \" \", \$p, PHP_EOL;"   # VM PHP path OK
wc -l lib/JIT/Builtin/StringSimilarTextJit.php'
# StringSimilarTextJit.php ~420 lines; AOT standalone links LLVM symbol __compiler_similar_text

Standalone inventory includes StringSimilarTextJit.php on bootstrap spine (docs/bootstrap-inventory.md).

Scope (this repo)

Piece	Path
PHP helper	ext/standard/SimilarTextJitHelper.php (new) wrapping VmString::similarText
JIT entry	replace StringSimilarTextJit::implement body with PHP trampoline
Delete/shrink	lib/JIT/Builtin/StringSimilarTextJit.php LLVM emitter
Tests	existing test/compliance/cases/stdlib/similar_text*.phpt; test/unit/JIT/*SimilarText*

Done when

• JIT + AOT standalone similar_text() output matches VM/Zend (percent + optional by-ref)
• StringSimilarTextJit.php LLVM line count reduced ≥80% (thin trampoline only)
• test/unit/AotRuntimeInventoryTest.php / runtime shrink tests updated
• ./script/ci-fast.sh --filter similar_text green

Links

Pattern: #9496 (CtypeJitHelper), #9626 (PregReplacementExpand) · #1492

[PurHur]

claim: PHP Runtime → PHP — starting this run (#9731 StringSimilarTextJit → SimilarTextJitHelper)

[PurHur]

Merged via #9739.

PHP path: ext/standard/SimilarTextJitHelper.php → VmString::similar_text() (php-src ext/standard/string.c).

LLVM shrink: StringSimilarTextJit.php 420 → 17 lines (compat shim); bridge lives in StringSimilarText.php. Deleted __phpc_similar_str / __phpc_similar_char / hand-written Oliver loops (−297 net lines).

Verification:

• vendor/bin/phpunit --filter SimilarText — OK (11 tests)
• make bootstrap-selfhost-vm-driver-execute-probe — OK
• php script/check-selfhost-spine-coverage-sync.php — OK