JIT: htmlspecialchars() native fast path (ENT_QUOTES, UTF-8)

[PurHur]

Problem

ext/standard/JitHtmlspecialchars.php exists but web output must be correct and fast for every echo chain. VM delegates to VmString::htmlspecialchars; JIT may fall back or have incomplete flag handling.

Goal

htmlspecialchars($s, ENT_QUOTES, 'UTF-8') matches PHP for & < > " ' on VM and JIT without calling Zend.

Implementation plan

1. Audit JitHtmlspecialchars vs VmString::htmlspecialchars parity.
2. Implement ENT_QUOTES / ENT_HTML5 subset in LLVM (table-driven entity replace).
3. Compliance PHPT mirroring test/real/cases/web_htmlspecialchars.phpt under JIT suite (CI: Run JIT compliance tests in CI (fix LLVM skip in PHPUnit) #98).
4. Fuzz edge: empty string, UTF-8 multibyte (reject or pass per Docs: Rewrite README feature list to match current compiler (2026) #48 docs).

Acceptance criteria

• JIT compliance passes web htmlspecialchars cases
• Php stdlib specs implementation #1-SimpleWeb / Php stdlib specs implementation #2-StaticWeb JIT benchmarks unchanged or faster

Related

• CI: Run JIT compliance tests in CI (fix LLVM skip in PHPUnit) #98 JIT CI
• Reference app: examples/003-MiniWebApp (router, templates, forms) #67 MiniWebApp