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Check the return value of __get_cpuid().

This function can fail if CPUID is not supported or the maximum
 supported value of EAX is less than the requested one.
Check the return value and explicitly disable all SIMD if it does
 fail.
This was happening before implicitly because of the initialization
 of info[] to zero, but being explicit about it makes it less likely
 someone will break this behavior because they did not realize what
 was going on.

--- a/celt/x86/x86cpu.c

+++ b/celt/x86/x86cpu.c

@@ -81,7 +81,12 @@

     );

 #endif

 #elif defined(CPU_INFO_BY_C)

-    __get_cpuid(InfoType, &(CPUInfo[0]), &(CPUInfo[1]), &(CPUInfo[2]), &(CPUInfo[3]));

+    if !(__get_cpuid(InfoType, &(CPUInfo[0]), &(CPUInfo[1]), &(CPUInfo[2]), &(CPUInfo[3]))) {

+        /* Our function cannot fail, but __get_cpuid can.

+           Returning all zeroes will effectively disable all SIMD, which is

+            what we want on CPUs that don't support CPUID. */

+        CPUInfo[3] = CPUInfo[2] = CPUInfo[1] = CPUInfo[0] = 0;

+    }

 #endif

 }

@@ -98,7 +103,7 @@

 static void opus_cpu_feature_check(CPU_Feature *cpu_feature)

 {

-    unsigned int info[4] = {0};

+    unsigned int info[4];

     unsigned int nIds = 0;

     cpuid(info, 0);