https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85494
--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> --- Author: redi Date: Wed May 29 14:45:35 2019 New Revision: 271740 URL: https://gcc.gnu.org/viewcvs?rev=271740&root=gcc&view=rev Log: PR libstdc++/85494 use rdseed and rand_s in std::random_device Add support for additional sources of randomness to std::random_device, to allow using RDSEED for Intel CPUs and rand_s for Windows. When supported these can be selected using the tokens "rdseed" and "rand_s". For *-w64-mingw32 targets the "default" token will now use rand_s, and for other i?86-*-* and x86_64-*-* targets it will try to use "rdseed" first, then "rdrand", and finally "/dev/urandom". To simplify the declaration of std::random_device in <bits/random.h> the constructors now unconditionally call _M_init instead of _M_init_pretr1, and the function call operator now unconditionally calls _M_getval. The library code now decides whether _M_init and _M_getval should use a real source of randomness or the mt19937 engine. Existing code compiled against old libstdc++ headers will still call _M_init_pretr1 and _M_getval_pretr1, but those functions now forward to _M_init and _M_getval if a real source of randomness is available. This means existing code compiled for mingw-w64 will start to use rand_s just by linking to a new libstdc++.dll. * acinclude.m4 (GLIBCXX_CHECK_X86_RDSEED): Define macro to check if the assembler supports rdseed. * config.h.in: Regenerate. * configure: Regenerate. * configure.ac: Use GLIBCXX_CHECK_X86_RDSEED. * config/os/mingw32-w64/os_defines.h (_GLIBCXX_USE_CRT_RAND_S): Define. * doc/html/*: Regenerate. * doc/xml/manual/status_cxx2011.xml: Document new tokens. * include/bits/random.h (random_device::random_device()): Always call _M_init rather than _M_init_pretr1. (random_device::random_device(const string&)): Likewise. (random_device::operator()()): Always call _M_getval(). (random_device::_M_file): Replace first member of union with an anonymous struct, with _M_file as its first member. * src/c++11/random.cc [_GLIBCXX_X86_RDRAND] (USE_RDRAND): Define. [_GLIBCXX_X86_RDSEED] (USE_RDSEED): Define. (USE_MT19937): Define if none of the above are defined. (USE_POSIX_FILE_IO): Define. (_M_strtoul): Remove. [USE_RDSEED] (__x86_rdseed): Define new function. [_GLIBCXX_USE_CRT_RAND_S] (__winxp_rand_s): Define new function. (random_device::_M_init(const string&)): Initialize new union members. Add support for "rdseed" and "rand_s" tokens. Decide what the "default" token does according to which USE_* macros are defined. [USE_POSIX_FILE_IO]: Store a file descriptor. [USE_MT19937]: Forward to _M_init_pretr1 instead. (random_device::_M_init_pretr1(const string&)) [USE_MT19937]: Inline code from _M_strtoul. [!USE_MT19937]: Call _M_init, transforming the old default token or numeric tokens to "default". (random_device::_M_fini()) [USE_POSIX_FILE_IO]: Use close not fclose. (random_device::_M_getval()): Use new union members to obtain a random number from the stored function pointer or file descriptor. [USE_MT19937]: Obtain a value from the mt19937 engine. (random_device::_M_getval_pretr1()): Call _M_getval(). (random_device::_M_getentropy()) [USE_POSIX_FILE_IO]: Use _M_fd instead of fileno. [!USE_MT19937] (mersenne_twister): Do not instantiate when not needed. * testsuite/26_numerics/random/random_device/85494.cc: New test. Added: trunk/libstdc++-v3/testsuite/26_numerics/random/random_device/85494.cc Modified: trunk/libstdc++-v3/ChangeLog trunk/libstdc++-v3/acinclude.m4 trunk/libstdc++-v3/config.h.in trunk/libstdc++-v3/config/os/mingw32-w64/os_defines.h trunk/libstdc++-v3/configure trunk/libstdc++-v3/configure.ac trunk/libstdc++-v3/doc/html/manual/appendix_contributing.html trunk/libstdc++-v3/doc/html/manual/status.html trunk/libstdc++-v3/doc/xml/manual/status_cxx2011.xml trunk/libstdc++-v3/include/bits/random.h trunk/libstdc++-v3/src/c++11/random.cc
