Req #72833 [NEW]: Use RDRND operand instead of Mersenne Twister

From: benjamin dot balet at gmail dot com Operating system: PHP version: Irrelevant Package: *Math Functions Bug Type: Feature/Change Request Bug description:Use RDRND operand instead of Mersenne Twister Description: ------------ There are many non-cryptographic applications using the rand function of PHP and I was wondering if it is worth the effort to implement a call to the hardware function RDRND if it is supported by the platform. Benefits of using RDRND: * It is seeded with a true random number generator. * Better source of random numbers than Mersenne Twister algorithm. Concerns of using RDRND: * This operand is available on recent Intel CPUs (Ivy Bridge) and only in the coming Zen AMD Architecture. * A bit slower than Mersenne Twister (if we omit the time it takes to seed the algo from the benchmark). Benefits of current PHP implementation: * The code is faster than RDRND if we don't count the generation of the seed number. Concerns of current PHP implementation: * A hard-coded limit of a 32 bits integer causes the need of two calls and a shift of the result so as to create a 64 bits number. * If the generator is not seeded, the PHP makes a syscall in order to get the PID of PHP, whereas RDRND is seeded. * Maybe considered as obsolete (see #67795). The implementation (ext/standard/mt_rand.c) would look like #ifdef __RDRND__ #include <immintrin.h> // No need to call GENERATE_SEED() # ifdef ZEND_ENABLE_ZVAL_LONG64 // Call to _rdrand64_step(uint64_t*); # else // Call to _rdrand32_step(uint32_t*); # endif #else //current PHP implementation #endif -- Edit bug report at https://bugs.php.net/bug.php?id=72833&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=72833&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=72833&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=72833&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=72833&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=72833&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=72833&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=72833&r=needscript Try newer version: https://bugs.php.net/fix.php?id=72833&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=72833&r=support Expected behavior: https://bugs.php.net/fix.php?id=72833&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=72833&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=72833&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=72833&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=72833&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=72833&r=dst IIS Stability: https://bugs.php.net/fix.php?id=72833&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=72833&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=72833&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=72833&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=72833&r=mysqlcfg