extphprs / ext-php-rs / 23717201024

34%

master: 65%

push

github

perf: use `zend_string_init_fast()` for non-persistent strings

Eliminate heap allocations for empty and single-character PHP strings by
routing non-persistent allocations through `zend_string_init_fast()`,
which returns PHP's pre-allocated interned globals (`zend_empty_string`
and `zend_one_char_string[256]`) instead of calling `emalloc`.

Available since PHP 8.0, `zend_string_release()` is a no-op on interned
strings (`ZSTR_IS_INTERNED` guard), so `ZBox::drop()` remains safe with
no Rust-side ownership changes needed.

The interned string globals are declared as weak symbols via
`#pragma weak` so the extension `.so` can be loaded outside of PHP
(e.g. by `cargo-php stubs`). When the globals are unavailable or
uninitialized, the fast path is skipped and `zend_string_init()` is
used as fallback.

Also fix `set_zend_string()` to detect interned strings via
`GC_IMMUTABLE` and set `InternedStringEx` type flags instead of
`StringEx`. Without this, PHP's debug build asserts when destroying
interned strings stored in zvals marked as refcounted. This fixes 4
pre-existing integration test failures on debug PHP builds.

5 of 5 new or added lines in 1 file covered. (100.0%)

2215 of 6495 relevant lines covered (34.1%)

23.76 hits per line