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random.cc (random_device::_M_init): Check whether cpuid instruction is available by using __get_cpuid_max.

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* src/c++11/random.cc (random_device::_M_init): Check whether cpuid
	instruction is available by using __get_cpuid_max.

From-SVN: r190982
This commit is contained in:
Ulrich Drepper 2012-09-05 13:54:57 +00:00 committed by Ulrich Drepper
parent 4700dd70e1
commit efc622f843
2 changed files with 6 additions and 4 deletions
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3
libstdc++-v3/ChangeLog
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@ -1,5 +1,8 @@
2012-09-05 Ulrich Drepper <drepper@gmail.com>
* src/c++11/random.cc (random_device::_M_init): Check whether cpuid
instruction is available by using __get_cpuid_max.
* include/ext/random.tcc (__gnu_cxx:normal_mv_distribution<>)
(operator()): Use __generate() function of _M_nd.

7
libstdc++-v3/src/c++11/random.cc
View File

@ -77,9 +77,9 @@ namespace std _GLIBCXX_VISIBILITY(default)
{
#if defined __i386__ || defined __x86_64__
unsigned int eax, ebx, ecx, edx;
__cpuid(0, eax, ebx, ecx, edx);
// Check for "GenuineIntel"
if (ebx == 0x756e6547 && ecx == 0x6c65746e && edx == 0x49656e69)
// Check availability of cpuid and, for now at least, also the
// CPU signature for Intel's
if (__get_cpuid_max(0, &ebx) > 0 && ebx == 0x756e6547)
{
__cpuid(1, eax, ebx, ecx, edx);
if (ecx & bit_RDRND)
@ -104,7 +104,6 @@ namespace std _GLIBCXX_VISIBILITY(default)
void
random_device::_M_init_pretr1(const std::string& token)
{
_M_mt.seed(_M_strtoul(token));
}