Bug #81272 [Ver->Csd]: Segfault in var[] after array_slice with JIT

Edit report at https://bugs.php.net/bug.php?id=81272&edit=1 ID: 81272 Updated by: git@php.net Reported by: dktapps at pmmp dot io Summary: Segfault in var[] after array_slice with JIT -Status: Verified +Status: Closed Type: Bug Package: JIT Operating System: Windows 10 PHP Version: 8.0.8 Assigned To: dmitry Block user comment: N Private report: N New Comment: Automatic comment on behalf of nikic Revision: https://github.com/php/php-src/commit/051ff33660858effe0d16137ebcfb9e120051dd5 Log: Fix bug #81272: Fix func info for functions returning EMPTY_ARRAY Previous Comments: ------------------------------------------------------------------------ [2021-07-20 12:10:53] nikic@php.net SEPARATE_ARRAY currently only does something if MAY_BE_RCN. However, we also need to separate immutable arrays. I'm not sure how this is intended to work. Should array_slice func info specify MAY_BE_RCN, or should SEPARATE_ARRAY be adjusted to always take possible immutable array into account? ------------------------------------------------------------------------ [2021-07-20 11:21:14] nikic@php.net Reduced: function test() { $newPages = array_slice([], 0, 0); $newPages[] = null; } test(); Presumably the case where array_slice() returns an interned empty array is not handled. ------------------------------------------------------------------------ [2021-07-18 19:25:54] dktapps at pmmp dot io Description: ------------ When running the below script in PHP 8.0, a segfault occurs if opcache JIT is enabled (opcache.jit=1205). The following settings were used to reproduce the problem: opcache.enable_cli=1 opcache.jit=1205 opcache.jit_buffer_size=128M Test script: --------------- <?php class WritableBookPage{ public function __construct(string $text){} } class WritableBookBase{ /** * @var WritableBookPage[] * @phpstan-var list<WritableBookPage> */ private $pages = []; /** * Inserts a new page with the given text and moves other pages upwards. * * @return $this */ public function insertPage(int $pageId, string $pageText = "") : self{ if($pageId < 0 || $pageId > count($this->pages)){ throw new \InvalidArgumentException("Page ID must not be negative"); } $newPages = array_slice($this->pages, 0, $pageId); $newPages[] = new WritableBookPage($pageText); array_push($newPages, ...array_slice($this->pages, $pageId)); $this->pages = $newPages; return $this; } } $book = new WritableBookBase; $book->insertPage(0, "test"); Expected result: ---------------- The script should return with no output with exit code 0. Actual result: -------------- A segmentation fault occurs. In VS, the following stacktrace appears: > [Inline Frame] php8ts.dll!zend_hash_real_init_packed_ex(_zend_array *) Line 159 C [Inline Frame] php8ts.dll!_zend_hash_index_add_or_update_i(_zend_array *) Line 1037 C php8ts.dll!zend_hash_next_index_insert(_zend_array * ht, _zval_struct * pData) Line 1104 C [External Code] php8ts.dll!zend_file_handle_dtor(_zend_file_handle * fh) Line 226 C [External Code] php8ts.dll!zend_execute(_zend_op_array * op_array, _zval_struct * return_value) Line 58877 C php8ts.dll!zend_execute_scripts(int type, _zval_struct * retval, int file_count, ...) Line 1681 C php8ts.dll!php_execute_script(_zend_file_handle * primary_file) Line 2516 C php.exe!do_cli(int argc, char * * argv) Line 951 C php.exe!main(int argc, char * * argv) Line 1336 C [External Code] Additionally, in a Linux debug run (see https://github.com/dktapps/php-8-jit-bugs/runs/3098555756?check_suite_focus=true), the following assertion failure appears: php: /tmp/php-build/source/8.0.7/Zend/zend_hash.c:987: _zend_hash_index_add_or_update_i: Assertion `(zend_gc_refcount(&(ht)->gc) == 1) || ((ht)->u.flags & (1<<6))' failed. Aborted (core dumped) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=81272&edit=1