Bug #73923 [Opn->Wfx]: Different floating point results with on modern machines (-ffp-contract)

Edit report at https://bugs.php.net/bug.php?id=73923&edit=1 ID: 73923 Updated by: derick@php.net Reported by: christophm30 at gmail dot com Summary: Different floating point results with on modern machines (-ffp-contract) -Status: Open +Status: Wont fix Type: Bug Package: Date/time related Operating System: all PHP Version: Irrelevant Block user comment: N Private report: N New Comment: Thanks for letting us know, but this is not really an issue for the time of sun rise, as this is so sub-second that nobody will ever notice. If you still care about this, please open a new ticket at https://github.com/php/php-src Previous Comments: ------------------------------------------------------------------------ [2021-06-17 02:39:31] Ramdolph23 at gmail dot com The following pull request has been associated: Patch Name: Changes to doc-base for error page refactoring On GitHub: https://github.com/php/doc-base/pull/13 Patch: https://github.com/php/doc-base/pull/13.patch ------------------------------------------------------------------------ [2017-01-12 20:38:25] christophm30 at gmail dot com Description: ------------ As described in https://github.com/facebook/hhvm/issues/7594 there are new FMA (floating-point multiply-add) instructions, which are emitted when the target system supports them (GCC needs -O2 or higher). The advantage of those instructions is that the provide more accurate results, but that also means different results. In HHVM this resulted in a self-test to fail. As the calculated (and unexpected) value could be reproduced with PHP7 on an arm64 machine (Ubuntu Xenial) as well, I want to bring this up here in the PHP bugtracker as well. Test script: --------------- From https://github.com/facebook/hhvm/blob/master/hphp/test/slow/ext_date/date_sunrise_test.php: date_default_timezone_set("Asia/Calcutta"); var_dump( date_sunrise(mktime(0, 0, 0, 12, 26, 2012), SUNFUNCS_RET_DOUBLE) ); We got 9.6226631046689 instead of 9.622663104669. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=73923&edit=1