php-in-php: preg_match() JIT — delete preg_match.c (~112 lines), lower from ext/standard/VmPreg.php

[PurHur]

Category

php-in-php | stdlib | bootstrap

Problem

JIT (and AOT) currently reuse a hand-written native regex runtime:

• lib/AOT/runtime/preg_match.c

That keeps PCRE semantics in C and blocks the PHP-in-PHP goal (#1492). This repo already has a PHP implementation surface in ext/standard/:

• ext/standard/VmPreg.php
• ext/standard/VmPregNative.php (FFI to libpcre2-8)

We should delete the C runtime helper (or shrink it to a minimal ABI shim) and lower preg_match()/friends via the PHP VM semantics so VM/JIT/AOT share one source of truth.

php-src reference

• ext/pcre/php_pcre.c — preg_match, preg_match_all, preg_replace, preg_replace_callback, preg_last_error, preg_last_error_msg

Repro

test/repro-maintainer/preg_match_basic.php:

<?php
var_dump(preg_match('/a./', 'abc', $m));
var_export($m);
echo "\n";

Run:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php test/repro-maintainer/preg_match_basic.php
php bin/vm.php test/repro-maintainer/preg_match_basic.php
php bin/jit.php test/repro-maintainer/preg_match_basic.php
'

Expected (Zend):

int(1)
array (
  0 => 'ab',
)

Scope (this repo)

• Delete or shrink: lib/AOT/runtime/preg_match.c
• VM SSOT:
  • ext/standard/VmPreg.php
  • ext/standard/VmPregNative.php
• JIT builtin lowering: lib/JIT/Builtin/StringPregMatch.php should link/lower to the PHP path (no new C logic).
• Add compliance tests:
  • test/compliance/cases/stdlib/preg_match_basic.phpt
  • test/compliance/cases/stdlib/preg_last_error_msg.phpt

Done when

• JIT/AOT no longer depends on preg_match.c for semantics (file removed or reduced to a minimal ABI shim)
• Repro output matches Zend on VM and JIT/AOT
• ./script/ci-fast.sh --filter preg_match is green
• Implementing PR notes C runtime reduction (lines removed / symbols deleted)

Related

• php-in-php: parse_str() JIT/AOT — delete lib/AOT/runtime/phpc_parse_str.c, share VmParseStr PHP semantics #6013 parse_str C migration
• php-in-php: unserialize() parser — delete phpc_unserialize.c, VmUnserialize PHP path for VM+JIT+AOT #5991 unserialize C migration
• Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 north star

[PurHur]

claim: PHP Runtime → PHP — starting this run (#5289: migrate preg_match.c to StringPregMatchJit LLVM lowering from VmPregNative semantics, delete lib/AOT/runtime/preg_match.c).

[PurHur]

Merged via #6600.

C shrink: deleted lib/AOT/runtime/preg_match.c (536 lines); removed from lib/AOT/Linker.php.

PHP path: lib/JIT/Builtin/StringPregMatchJit.php emits LLVM for __compiler_preg_* via libpcre2-8 externals; StringPregMatch.php delegates (no clang bitcode link).

Verification (Docker harness): issue repro green on VM+JIT; vendor/bin/phpunit --filter 'preg_match_jit|preg_replace_jit|preg_last_error_jit|preg_match_all_jit|preg_grep_jit' → OK (9/9); shrink test OK.