random.cc (random_device::_M_init): Check whether cpuid instruction is available…

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


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

From-SVN: r190982

libstdc++-v3/ChangeLog

 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.
 

libstdc++-v3/src/c++11/random.cc

@@ -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));
   }