From: anton at samba dot org Operating system: Linux/RHEL5.2/PowerPC64 PHP version: 5.2.6 PHP Bug Type: Compile Failure Bug description: Pointer aliasing issue results in miscompile on gcc4.4
Description: ------------ A recent checkout of gcc4.4 miscompiles php on PowerPC64. The following function reads from p via long * and stores to p via void * which violates aliasing rules: static inline void zend_ptr_stack_clear_multiple(TSRMLS_D) { void **p = EG(argument_stack).top_element-2; int delete_count = (int)(zend_uintptr_t) *p; EG(argument_stack).top -= (delete_count+2); while (--delete_count>=0) { zval *q = *(zval **)(--p); *p = NULL; zval_ptr_dtor(&q); } EG(argument_stack).top_element = p; } More details can be found at: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37824 We can remove the (zval **) cast so that we read and write via void *p and fix the aliasing issue. I will attach a patch. -- Edit bug report at http://bugs.php.net/?id=46311&edit=1 -- Try a CVS snapshot (PHP 5.2): http://bugs.php.net/fix.php?id=46311&r=trysnapshot52 Try a CVS snapshot (PHP 5.3): http://bugs.php.net/fix.php?id=46311&r=trysnapshot53 Try a CVS snapshot (PHP 6.0): http://bugs.php.net/fix.php?id=46311&r=trysnapshot60 Fixed in CVS: http://bugs.php.net/fix.php?id=46311&r=fixedcvs Fixed in release: http://bugs.php.net/fix.php?id=46311&r=alreadyfixed Need backtrace: http://bugs.php.net/fix.php?id=46311&r=needtrace Need Reproduce Script: http://bugs.php.net/fix.php?id=46311&r=needscript Try newer version: http://bugs.php.net/fix.php?id=46311&r=oldversion Not developer issue: http://bugs.php.net/fix.php?id=46311&r=support Expected behavior: http://bugs.php.net/fix.php?id=46311&r=notwrong Not enough info: http://bugs.php.net/fix.php?id=46311&r=notenoughinfo Submitted twice: http://bugs.php.net/fix.php?id=46311&r=submittedtwice register_globals: http://bugs.php.net/fix.php?id=46311&r=globals PHP 4 support discontinued: http://bugs.php.net/fix.php?id=46311&r=php4 Daylight Savings: http://bugs.php.net/fix.php?id=46311&r=dst IIS Stability: http://bugs.php.net/fix.php?id=46311&r=isapi Install GNU Sed: http://bugs.php.net/fix.php?id=46311&r=gnused Floating point limitations: http://bugs.php.net/fix.php?id=46311&r=float No Zend Extensions: http://bugs.php.net/fix.php?id=46311&r=nozend MySQL Configuration Error: http://bugs.php.net/fix.php?id=46311&r=mysqlcfg