Assertion failure Zend/zend_vm_execute.h JIT

[YuanchengJiang]

Description

The following code:

<?php
class B {
public int $fusion;
}
class C extends B {
}
class D extends C {
public function __destruct() {
}
}
$tests = [
[C::class, new C()],
[C::class, new B()],
[D::class, new B()],
];
foreach ($tests as [$class, $instance]) {
$obj = (new ReflectionClass($class))->newLazyProxy(function ($obj) use ($instance) {
$instance->b = 1;
return $instance;
});
var_dump($obj->b);
}

Resulted in this output:

php: Zend/zend_vm_execute.h:18745: int ZEND_SEND_VAL_SPEC_TMPVAR_UNUSED_HANDLER(zend_execute_data *): Assertion `!(((zend_executor_globals *) (((char*) _tsrm_ls_cache)+(executor_globals_offset)))->exception)' failed.
Aborted (core dumped)

To reproduce:

./php-src/sapi/cli/php  -d "opcache.jit_hot_func=1" -d "opcache.jit_hot_side_exit=1" -d "zend_extension=/home/phpfuzz/WorkSpace/flowfusion/php-src/modules/opcache.so" -d "opcache.enable_cli=1" -d "opcache.jit=1254" ./test.php

Commit:

ac9392b855cc4db6792a8379223e1fd1bbebd157

Configurations:

CC="clang-12" CXX="clang++-12" CFLAGS="-DZEND_VERIFY_TYPE_INFERENCE" CXXFLAGS="-DZEND_VERIFY_TYPE_INFERENCE" ./configure --enable-debug --enable-address-sanitizer --enable-undefined-sanitizer --enable-re2c-cgoto --enable-fpm --enable-litespeed --enable-phpdbg-debug --enable-zts --enable-bcmath --enable-calendar --enable-dba --enable-dl-test --enable-exif --enable-ftp --enable-gd --enable-gd-jis-conv --enable-mbstring --enable-pcntl --enable-shmop --enable-soap --enable-sockets --enable-sysvmsg --enable-zend-test --with-zlib --with-bz2 --with-curl --with-enchant --with-gettext --with-gmp --with-mhash --with-ldap --with-libedit --with-readline --with-snmp --with-sodium --with-xsl --with-zip --with-mysqli --with-pdo-mysql --with-pdo-pgsql --with-pgsql --with-sqlite3 --with-pdo-sqlite --with-webp --with-jpeg --with-freetype --enable-sigchild --with-readline --with-pcre-jit --with-iconv

Operating System:

Ubuntu 20.04 Host, Docker 0599jiangyc/flowfusion:latest

This report is automatically generated by FlowFusion

PHP Version

ac9392b

Operating System

No response

[Girgias]

@arnaud-lb this seems to be related to lazy objects, could you have a look?

[arnaud-lb]

Simplified reproducer (without lazy objects) :

class B {
    public function __construct($init) {
        if ($init) {
            $this->b = $init;
        }
    }
}

$tests = [
    new B(1),
    new B(0),
];

set_error_handler(function () {
    throw new \Exception();
});

foreach ($tests as $obj) {
    var_dump($obj->b);
}

On the first iteration, $obj->b evaluates to int(1), but on the second one an exception is thrown.

The loop is JIT'ed and a type guard is emitted after fetching $obj->b (here). When the guard fails we side-exit before checking EG(exception) (here), so the assertion ZEND_ASSERT(!EG(exception)) fails in ZEND_SEND_VAL_SPEC_TMPVAR_UNUSED_HANDLER:

---- TRACE 1 start (loop) $main() test2.php:20
int(1)
0014 FE_FETCH_R V2 CV1($obj) 0020 ; op1(packed array) op2(undef)
0015 INIT_FCALL 1 96 string("var_dump")
     >init var_dump
0016 T3 = FETCH_OBJ_R CV1($obj) string("b") ; op1(object of class B)
0017 SEND_VAL T3 1 ; op1(int)
0018 DO_ICALL
     >call var_dump
0019 JMP 0014
---- TRACE 1 stop (loop)
---- TRACE 1 exit info
     exit_5: 0017/0009/4/CALL X2:array X3:unknown(zval_copy(rax))
---- TRACE 1 compiled

[...]

     TRACE 1 exit 5 $main() test2.php:21
---- TRACE 2 start (side trace 1/5) $main() test2.php:21
php: Zend/zend_vm_execute.h:18744: ZEND_SEND_VAL_SPEC_TMPVAR_UNUSED_HANDLER: Assertion `!(executor_globals.exception)' failed.
Aborted (core dumped)

[arnaud-lb]

Thank you @YuanchengJiang!