diff --git a/docs/capabilities.md b/docs/capabilities.md
index 3b1dbc321de..0490b4da1fc 100644
--- a/docs/capabilities.md
+++ b/docs/capabilities.md
@@ -239,6 +239,7 @@ Auto-generated by `script/capability-matrix.php`. Do not edit by hand.
 | `sha1` | yes | yes | yes | standard | JIT PHPT; AOT PHPT |
 | `shell_exec` | yes | yes | yes | standard |  |
 | `shuffle` | yes | yes | yes | standard | JIT PHPT; AOT PHPT |
+| `similar_text` | yes | yes | yes | standard | JIT PHPT; AOT PHPT |
 | `sin` | yes | yes | yes | standard |  |
 | `sizeof` | yes | yes | yes | standard | JIT PHPT; AOT PHPT |
 | `sleep` | yes | yes | yes | standard | JIT PHPT |
diff --git a/docs/stdlib-jit-audit.md b/docs/stdlib-jit-audit.md
index 3f5efa27c7b..887ef419e3b 100644
--- a/docs/stdlib-jit-audit.md
+++ b/docs/stdlib-jit-audit.md
@@ -167,6 +167,7 @@ _None — all JIT `call()` builtins are lowered or deferred._
 - `krsort` — `ext/standard/krsort_.php`
 - `lcfirst` — `ext/standard/lcfirst.php`
 - `levenshtein` — `ext/standard/levenshtein.php`
+- `similar_text` — `ext/standard/similar_text.php`
 - `soundex` — `ext/standard/soundex.php`
 - `log` — `ext/standard/log.php`
 - `lstat` — `ext/standard/lstat_.php`
diff --git a/ext/standard/Module.php b/ext/standard/Module.php
index e4bead56cea..20f28f8bae2 100755
--- a/ext/standard/Module.php
+++ b/ext/standard/Module.php
@@ -57,6 +57,7 @@ public function getFunctions(): array
             new chr(),
             new strcmp(),
             new levenshtein(),
+            new similar_text(),
             new soundex(),
             new metaphone(),
             new strnatcmp(),
diff --git a/ext/standard/VmString.php b/ext/standard/VmString.php
index e02e1a39290..b272ffb1d55 100644
--- a/ext/standard/VmString.php
+++ b/ext/standard/VmString.php
@@ -598,6 +598,95 @@ public static function levenshtein(
         return $prev[$len2];
     }
 
+    /**
+     * similar_text() — PHP-compatible Oliver algorithm (issue #2445).
+     */
+    public static function similar_text(string $string1, string $string2, ?float &$percent = null): int
+    {
+        $len1 = self::byteLength($string1);
+        $len2 = self::byteLength($string2);
+        if ($len1 > 255 || $len2 > 255) {
+            throw new \ValueError(
+                'similar_text(): Argument #1 ($string1) or #2 ($string2) must be less than 256 characters'
+            );
+        }
+        if (0 === $len1 && 0 === $len2) {
+            if (null !== $percent) {
+                $percent = 0.0;
+            }
+
+            return 0;
+        }
+        $sim = self::similarChar($string1, $len1, $string2, $len2);
+        if (null !== $percent) {
+            $percent = $sim * 200.0 / ($len1 + $len2);
+        }
+
+        return $sim;
+    }
+
+    private static function similarStr(
+        string $txt1,
+        int $len1,
+        string $txt2,
+        int $len2,
+        int &$pos1,
+        int &$pos2,
+        int &$max,
+        int &$count
+    ): void {
+        $max = 0;
+        $count = 0;
+        for ($p = 0; $p < $len1; ++$p) {
+            for ($q = 0; $q < $len2; ++$q) {
+                $l = 0;
+                while (
+                    $p + $l < $len1
+                    && $q + $l < $len2
+                    && $txt1[$p + $l] === $txt2[$q + $l]
+                ) {
+                    ++$l;
+                }
+                if ($l > $max) {
+                    $max = $l;
+                    ++$count;
+                    $pos1 = $p;
+                    $pos2 = $q;
+                }
+            }
+        }
+    }
+
+    private static function similarChar(string $txt1, int $len1, string $txt2, int $len2): int
+    {
+        $pos1 = 0;
+        $pos2 = 0;
+        $max = 0;
+        $count = 0;
+        self::similarStr($txt1, $len1, $txt2, $len2, $pos1, $pos2, $max, $count);
+        $sum = $max;
+        if ($sum > 0) {
+            if ($pos1 > 0 && $pos2 > 0 && $count > 1) {
+                $sum += self::similarChar(
+                    substr($txt1, 0, $pos1),
+                    $pos1,
+                    substr($txt2, 0, $pos2),
+                    $pos2
+                );
+            }
+            if ($pos1 + $max < $len1 && $pos2 + $max < $len2) {
+                $sum += self::similarChar(
+                    substr($txt1, $pos1 + $max),
+                    $len1 - $pos1 - $max,
+                    substr($txt2, $pos2 + $max),
+                    $len2 - $pos2 - $max
+                );
+            }
+        }
+
+        return $sum;
+    }
+
     /**
      * metaphone() — PHP-compatible Metaphone on ASCII letters (issue #2423).
      */
diff --git a/ext/standard/similar_text.php b/ext/standard/similar_text.php
new file mode 100644
index 00000000000..70c0daa61fe
--- /dev/null
+++ b/ext/standard/similar_text.php
@@ -0,0 +1,70 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PHPCompiler\ext\standard;
+
+use PHPCompiler\Frame;
+use PHPCompiler\Func\Internal;
+use PHPCompiler\JIT\Builtin\StringSimilarText;
+use PHPCompiler\JIT\Context;
+use PHPCompiler\JIT\Variable as JITVariable;
+use PHPCompiler\VM\Variable;
+use PHPLLVM\Value;
+
+/**
+ * similar_text() — similarity between two strings (subset of PHP; issue #2445).
+ */
+final class similar_text extends Internal
+{
+    public function __construct()
+    {
+        parent::__construct('similar_text');
+    }
+
+    public function execute(Frame $frame): void
+    {
+        $argc = \count($frame->calledArgs);
+        if ($argc < 2 || $argc > 3) {
+            throw new \LogicException('similar_text() accepts two or three arguments in this compiler build');
+        }
+        $a = $frame->calledArgs[0]->resolveIndirect();
+        $b = $frame->calledArgs[1]->resolveIndirect();
+        if (Variable::TYPE_STRING !== $a->type || Variable::TYPE_STRING !== $b->type) {
+            throw new \LogicException('similar_text() requires two strings in this compiler build');
+        }
+        $s1 = $a->toString();
+        $s2 = $b->toString();
+        if (3 === $argc) {
+            $percent = 0.0;
+            $sim = VmString::similar_text($s1, $s2, $percent);
+            $frame->calledArgs[2]->resolveIndirect()->float($percent);
+        } else {
+            $sim = VmString::similar_text($s1, $s2);
+        }
+        if (null === $frame->returnVar) {
+            return;
+        }
+        $frame->returnVar->int($sim);
+    }
+
+    public Context $context;
+
+    public function call(Context $context, JITVariable ...$args): Value
+    {
+        $this->context = $context;
+        if (\count($args) !== 2) {
+            throw new \LogicException(
+                'similar_text() JIT/AOT only supports two arguments in this compiler build; use bin/vm.php for &$percent'
+            );
+        }
+        StringSimilarText::ensureLinked($context);
+        $p0 = $this->stringDataPtr($context, $this->jitString($context, $args[0], 'similar_text() argument #1'));
+        $p1 = $this->stringDataPtr($context, $this->jitString($context, $args[1], 'similar_text() argument #2'));
+        $fn = $context->lookupFunction('phpc_similar_text');
+        $i64 = $context->getTypeFromString('int64');
+        $raw = $context->builder->call($fn, $p0, $p1);
+
+        return $context->builder->sExt($raw, $i64);
+    }
+}
diff --git a/lib/AOT/Linker.php b/lib/AOT/Linker.php
index 106a2578c79..8ace059008d 100644
--- a/lib/AOT/Linker.php
+++ b/lib/AOT/Linker.php
@@ -21,6 +21,7 @@ final class Linker
         __DIR__.'/runtime/phpc_strnatcasecmp.c',
         __DIR__.'/runtime/phpc_substr_compare.c',
         __DIR__.'/runtime/phpc_levenshtein.c',
+        __DIR__.'/runtime/phpc_similar_text.c',
         __DIR__.'/runtime/phpc_soundex.c',
         __DIR__.'/runtime/phpc_metaphone.c',
         __DIR__.'/runtime/phpc_str_getcsv.c',
diff --git a/lib/AOT/runtime/builtin_function_names.inc b/lib/AOT/runtime/builtin_function_names.inc
index af77eaf4dbe..e26c12a04c1 100644
--- a/lib/AOT/runtime/builtin_function_names.inc
+++ b/lib/AOT/runtime/builtin_function_names.inc
@@ -230,6 +230,7 @@ static const char *phpc_builtin_functions[] = {
     "setrawcookie",
     "sha1",
     "shell_exec",
+    "similar_text",
     "shuffle",
     "sin",
     "sizeof",
diff --git a/lib/AOT/runtime/phpc_similar_text.c b/lib/AOT/runtime/phpc_similar_text.c
new file mode 100644
index 00000000000..8adddc523e5
--- /dev/null
+++ b/lib/AOT/runtime/phpc_similar_text.c
@@ -0,0 +1,94 @@
+/*
+ * similar_text() runtime for VM/JIT/AOT (issue #2445).
+ * PHP-compatible Oliver algorithm; byte-oriented; max 255 bytes per string.
+ */
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+#define PHPC_SIM_MAX_LEN 255
+
+static void phpc_similar_str(
+    const char *txt1,
+    size_t len1,
+    const char *txt2,
+    size_t len2,
+    size_t *pos1,
+    size_t *pos2,
+    size_t *max,
+    size_t *count
+)
+{
+    const char *p;
+    const char *q;
+    const char *end1 = txt1 + len1;
+    const char *end2 = txt2 + len2;
+    size_t l;
+
+    *max = 0;
+    *count = 0;
+    for (p = txt1; p < end1; p++) {
+        for (q = txt2; q < end2; q++) {
+            for (l = 0; (p + l < end1) && (q + l < end2) && (p[l] == q[l]); l++) {
+            }
+            if (l > *max) {
+                *max = l;
+                *count += 1;
+                *pos1 = (size_t) (p - txt1);
+                *pos2 = (size_t) (q - txt2);
+            }
+        }
+    }
+}
+
+static size_t phpc_similar_char(const char *txt1, size_t len1, const char *txt2, size_t len2)
+{
+    size_t sum;
+    size_t pos1 = 0;
+    size_t pos2 = 0;
+    size_t max = 0;
+    size_t count = 0;
+
+    phpc_similar_str(txt1, len1, txt2, len2, &pos1, &pos2, &max, &count);
+    sum = max;
+    if (sum) {
+        if (pos1 && pos2 && count > 1) {
+            sum += phpc_similar_char(txt1, pos1, txt2, pos2);
+        }
+        if ((pos1 + max < len1) && (pos2 + max < len2)) {
+            sum += phpc_similar_char(
+                txt1 + pos1 + max,
+                len1 - pos1 - max,
+                txt2 + pos2 + max,
+                len2 - pos2 - max
+            );
+        }
+    }
+
+    return sum;
+}
+
+int phpc_similar_text(const char *s1, const char *s2)
+{
+    size_t len1;
+    size_t len2;
+
+    if (NULL == s1) {
+        s1 = "";
+    }
+    if (NULL == s2) {
+        s2 = "";
+    }
+
+    len1 = strlen(s1);
+    len2 = strlen(s2);
+    if (len1 > PHPC_SIM_MAX_LEN || len2 > PHPC_SIM_MAX_LEN) {
+        return -1;
+    }
+    if (0 == len1 && 0 == len2) {
+        return 0;
+    }
+
+    return (int) phpc_similar_char(s1, len1, s2, len2);
+}
diff --git a/lib/BuiltinParamNames.php b/lib/BuiltinParamNames.php
index 275d79d0199..91cfcffe2b2 100644
--- a/lib/BuiltinParamNames.php
+++ b/lib/BuiltinParamNames.php
@@ -13,6 +13,7 @@ final class BuiltinParamNames
     private const MAP = [
         'strlen' => ['string'],
         'parse_str' => ['string', 'array'],
+        'similar_text' => ['string1', 'string2', 'percent'],
     ];
 
     /**
diff --git a/lib/JIT/Builtin/StringSimilarText.php b/lib/JIT/Builtin/StringSimilarText.php
new file mode 100644
index 00000000000..ecfb39f93b8
--- /dev/null
+++ b/lib/JIT/Builtin/StringSimilarText.php
@@ -0,0 +1,195 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PHPCompiler\JIT\Builtin;
+
+use PHPCompiler\JIT\Builtin;
+use PHPCompiler\JIT\Context;
+
+/**
+ * JIT MCJIT body for phpc_similar_text (string similarity count).
+ *
+ * Links {@see lib/AOT/runtime/phpc_similar_text.c}.
+ */
+final class StringSimilarText
+{
+    private const RUNTIME_SOURCE = __DIR__.'/../../AOT/runtime/phpc_similar_text.c';
+
+    public static function ensureLinked(Context $context): void
+    {
+        self::implement($context);
+    }
+
+    public static function implement(Context $context): void
+    {
+        if (Builtin::LOAD_TYPE_STANDALONE === $context->loadType) {
+            $fn = $context->module->getNamedFunction('phpc_similar_text');
+            if (null === $fn) {
+                $fn = self::declareStandalone($context);
+            }
+            $context->registerFunction('phpc_similar_text', $fn);
+
+            return;
+        }
+
+        $probe = $context->module->getNamedFunction('phpc_similar_text');
+        if (null !== $probe && $probe->countBasicBlocks() > 0) {
+            self::registerLinkedRuntime($context);
+
+            return;
+        }
+
+        $bitcode = self::ensureBitcode();
+        $data = file_get_contents($bitcode);
+        if (false === $data || '' === $data) {
+            throw new \LogicException('Failed to read phpc_similar_text JIT bitcode: '.$bitcode);
+        }
+        $buffer = $context->llvm->createMemoryBufferWithString($data, 'phpc_similar_text.bc');
+        $runtimeModule = $buffer->parseBitcode($context->context);
+        if (!$context->module->link($runtimeModule)) {
+            throw new \LogicException('Failed to link phpc_similar_text JIT runtime bitcode');
+        }
+
+        self::registerLinkedRuntime($context);
+    }
+
+    private static function declareStandalone(Context $context)
+    {
+        $ptr = $context->getTypeFromString('char*');
+        $i64 = $context->getTypeFromString('int64');
+        $ft = $context->context->functionType($i64, false, $ptr, $ptr);
+
+        return $context->module->addFunction('phpc_similar_text', $ft);
+    }
+
+    private static function registerLinkedRuntime(Context $context): void
+    {
+        $fn = $context->module->getNamedFunction('phpc_similar_text');
+        if (null === $fn) {
+            throw new \LogicException('phpc_similar_text missing after phpc_similar_text bitcode link');
+        }
+        $context->registerFunction('phpc_similar_text', $fn);
+    }
+
+    private static function ensureBitcode(): string
+    {
+        $source = realpath(self::RUNTIME_SOURCE);
+        if (false === $source || !is_file($source)) {
+            throw new \LogicException('phpc_similar_text runtime source not found: '.self::RUNTIME_SOURCE);
+        }
+
+        $compiler = self::resolveCompiler();
+        $cacheDir = sys_get_temp_dir().'/phpc-jit-runtime';
+        if (!is_dir($cacheDir) && !mkdir($cacheDir, 0777, true) && !is_dir($cacheDir)) {
+            throw new \LogicException('Cannot create JIT runtime cache: '.$cacheDir);
+        }
+
+        $cache = $cacheDir.'/'.basename($source, '.c').'-'.substr(
+            sha1($source.filemtime($source).$compiler.'host'),
+            0,
+            16
+        ).'.bc';
+        if (is_file($cache) && filemtime($cache) >= filemtime($source)) {
+            return $cache;
+        }
+
+        $includes = self::hostLibcIncludeFlags();
+        $cmd = escapeshellarg($compiler)
+            .' -emit-llvm -c -fPIC -O2'.$includes.' '
+            .escapeshellarg($source).' -o '.escapeshellarg($cache).' 2>&1';
+        $output = shell_exec($cmd);
+        if (!is_file($cache)) {
+            throw new \LogicException(
+                'Failed to compile phpc_similar_text JIT bitcode: '.trim((string) $output)
+            );
+        }
+
+        return $cache;
+    }
+
+    private static function resolveCompiler(): string
+    {
+        $llvmDir = getenv('PHP_COMPILER_LLVM_PATH');
+        if (false !== $llvmDir && '' !== $llvmDir) {
+            foreach (['clang-9', 'clang'] as $name) {
+                $candidate = $llvmDir.'/'.$name;
+                if (is_executable($candidate)) {
+                    return $candidate;
+                }
+            }
+        }
+
+        foreach (['clang-9', 'clang', 'gcc', 'cc'] as $name) {
+            $path = trim((string) shell_exec('command -v '.escapeshellarg($name).' 2>/dev/null'));
+            if ('' !== $path) {
+                return $path;
+            }
+        }
+
+        throw new \LogicException('No C compiler found for phpc_similar_text JIT runtime bitcode');
+    }
+
+    private static function hostLibcIncludeFlags(): string
+    {
+        $flags = '';
+        foreach (self::discoverSystemIncludeDirs() as $dir) {
+            $flags .= ' -isystem '.escapeshellarg($dir);
+        }
+        if ('' === $flags && is_file('/usr/include/stdio.h')) {
+            $flags = ' -isystem /usr/include';
+        }
+
+        return $flags;
+    }
+
+    /**
+     * @return list<string>
+     */
+    private static function discoverSystemIncludeDirs(): array
+    {
+        $dirs = [];
+        foreach (['gcc', 'cc', 'clang'] as $compiler) {
+            $path = trim((string) shell_exec('command -v '.escapeshellarg($compiler).' 2>/dev/null'));
+            if ('' === $path) {
+                continue;
+            }
+            $verbose = shell_exec(
+                escapeshellarg($path).' -E -Wp,-v -xc /dev/null 2>&1'
+            );
+            if (!is_string($verbose)) {
+                continue;
+            }
+            $capture = false;
+            foreach (explode("\n", $verbose) as $line) {
+                if (str_contains($line, '#include <...> search starts here:')) {
+                    $capture = true;
+
+                    continue;
+                }
+                if ($capture) {
+                    if (str_contains($line, 'End of search list')) {
+                        break;
+                    }
+                    $dir = trim($line);
+                    if ('' !== $dir && is_dir($dir)) {
+                        $dirs[$dir] = true;
+                    }
+                }
+            }
+            if ([] !== $dirs) {
+                break;
+            }
+        }
+
+        if ([] === $dirs) {
+            foreach (['/usr/include', '/usr/include/x86_64-linux-gnu'] as $fallback) {
+                if (is_dir($fallback)) {
+                    $dirs[$fallback] = true;
+                }
+            }
+        }
+
+        return array_keys($dirs);
+    }
+}
diff --git a/test/compliance/SimilarTextJITTest.php b/test/compliance/SimilarTextJITTest.php
new file mode 100644
index 00000000000..e1497fd8ffe
--- /dev/null
+++ b/test/compliance/SimilarTextJITTest.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PHPCompiler;
+
+require_once __DIR__.'/../BaseTest.php';
+
+/** JIT compliance for similar_text(). */
+final class SimilarTextJITTest extends BaseTest
+{
+    protected static string $DIR = __DIR__;
+
+    public static function providePHPTests(): \Generator
+    {
+        yield 'similar_text_jit.phpt' => self::parsePHPT(
+            __DIR__.'/cases/stdlib/similar_text_jit.phpt',
+            'similar_text_jit.phpt'
+        );
+    }
+
+    public function setUp(): void
+    {
+        $this->BIN = realpath(__DIR__.'/../../bin/jit.php');
+    }
+}
diff --git a/test/compliance/SimilarTextVMTest.php b/test/compliance/SimilarTextVMTest.php
new file mode 100644
index 00000000000..e07c5cc3632
--- /dev/null
+++ b/test/compliance/SimilarTextVMTest.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PHPCompiler;
+
+require_once __DIR__.'/../BaseTest.php';
+
+/** VM compliance for similar_text(). */
+final class SimilarTextVMTest extends BaseTest
+{
+    protected static string $DIR = __DIR__;
+
+    public static function providePHPTests(): \Generator
+    {
+        yield 'similar_text.phpt' => self::parsePHPT(
+            __DIR__.'/cases/stdlib/similar_text.phpt',
+            'similar_text.phpt'
+        );
+    }
+
+    public function setUp(): void
+    {
+        $this->BIN = realpath(__DIR__.'/../../bin/vm.php');
+    }
+}
diff --git a/test/compliance/cases/stdlib/similar_text.phpt b/test/compliance/cases/stdlib/similar_text.phpt
new file mode 100644
index 00000000000..6c9330526ce
--- /dev/null
+++ b/test/compliance/cases/stdlib/similar_text.phpt
@@ -0,0 +1,30 @@
+--TEST--
+stdlib similar_text() (#2445)
+--FILE--
+<?php
+echo similar_text('Hello World', 'Hello PHP'), "\n";
+similar_text('Hello World', 'Hello PHP', $p);
+echo $p, "\n";
+echo similar_text('kitten', 'sitting'), "\n";
+similar_text('kitten', 'sitting', $p2);
+echo $p2, "\n";
+echo similar_text('abc', 'abc'), "\n";
+similar_text('abc', 'abc', $p3);
+echo $p3, "\n";
+echo similar_text('', ''), "\n";
+similar_text('', '', $p4);
+echo $p4, "\n";
+echo similar_text('first', 'second'), "\n";
+similar_text('first', 'second', $p5);
+echo $p5, "\n";
+--EXPECT--
+6
+60
+4
+61.538461538462
+3
+100
+0
+0
+1
+18.181818181818
diff --git a/test/compliance/cases/stdlib/similar_text_jit.phpt b/test/compliance/cases/stdlib/similar_text_jit.phpt
new file mode 100644
index 00000000000..46869641b87
--- /dev/null
+++ b/test/compliance/cases/stdlib/similar_text_jit.phpt
@@ -0,0 +1,11 @@
+--TEST--
+JIT: similar_text() (#2445)
+--FILE--
+<?php
+echo similar_text('Hello World', 'Hello PHP'), "\n";
+echo similar_text('kitten', 'sitting'), "\n";
+echo similar_text('abc', 'abc'), "\n";
+--EXPECT--
+6
+4
+3
diff --git a/test/fixtures/aot/cases/similar_text.phpt b/test/fixtures/aot/cases/similar_text.phpt
new file mode 100644
index 00000000000..3ecdc70c332
--- /dev/null
+++ b/test/fixtures/aot/cases/similar_text.phpt
@@ -0,0 +1,11 @@
+--TEST--
+AOT: similar_text() (#2445)
+--FILE--
+<?php
+echo similar_text('Hello World', 'Hello PHP'), "\n";
+echo similar_text('kitten', 'sitting'), "\n";
+echo similar_text('abc', 'abc'), "\n";
+--EXPECT--
+6
+4
+3
diff --git a/test/unit/SimilarTextBuiltinTest.php b/test/unit/SimilarTextBuiltinTest.php
new file mode 100644
index 00000000000..3127214abf6
--- /dev/null
+++ b/test/unit/SimilarTextBuiltinTest.php
@@ -0,0 +1,56 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PHPCompiler;
+
+use PHPCompiler\ext\standard\similar_text;
+use PHPCompiler\VM\Variable as VMVariable;
+use PHPUnit\Framework\TestCase;
+
+/** VM builtin for similar_text(). */
+final class SimilarTextBuiltinTest extends TestCase
+{
+    public function testHelloWorld(): void
+    {
+        $this->assertSame(6, $this->runSimilarText('Hello World', 'Hello PHP'));
+    }
+
+    public function testPercentByReference(): void
+    {
+        $percent = 0.0;
+        $sim = $this->runSimilarText('Hello World', 'Hello PHP', $percent);
+        $this->assertSame(6, $sim);
+        $this->assertEqualsWithDelta(60.0, $percent, 0.0001);
+    }
+
+    public function testEmptyStrings(): void
+    {
+        $this->assertSame(0, $this->runSimilarText('', ''));
+    }
+
+    private function runSimilarText(string $a, string $b, ?float &$percent = null): int
+    {
+        $runtime = new Runtime();
+        $fn = new similar_text();
+        $frame = $fn->getFrame($runtime->vmContext);
+        $args = [new VMVariable(), new VMVariable()];
+        $args[0]->string($a);
+        $args[1]->string($b);
+        if (null !== $percent) {
+            $ref = new VMVariable();
+            $holder = new VMVariable();
+            $holder->float(0.0);
+            $ref->indirect($holder);
+            $args[] = $ref;
+        }
+        $frame->calledArgs = $args;
+        $frame->returnVar = new VMVariable();
+        $fn->execute($frame);
+        if (null !== $percent && 3 === \count($args)) {
+            $percent = $args[2]->resolveIndirect()->toFloat();
+        }
+
+        return $frame->returnVar->toInt();
+    }
+}