Test whether OS supports AVX512

Signed-off-by: Stefan Weil <sw@weilnetz.de>

Author: stweil

src/arch/simddetect.cpp

@@ -171,9 +171,12 @@ SIMDDetect::SIMDDetect() {
         // be used inside an if.
         __cpuid_count(7, 0, eax, ebx, ecx, edx);
         avx2_available_ = (ebx & 0x00000020) != 0;
-        avx512F_available_ = (ebx & 0x00010000) != 0;
-        avx512BW_available_ = (ebx & 0x40000000) != 0;
-        avx512VNNI_available_ = (ecx & 0x00000800) != 0;
+        if ((xgetbv() & 0xe0) == 0xe0) {
+          // OS supports AVX512.
+          avx512F_available_ = (ebx & 0x00010000) != 0;
+          avx512BW_available_ = (ebx & 0x40000000) != 0;
+          avx512VNNI_available_ = (ecx & 0x00000800) != 0;
+        }
       }
 #      endif
     }
@@ -202,9 +205,12 @@ SIMDDetect::SIMDDetect() {
       if (max_function_id >= 7) {
         __cpuid(cpuInfo, 7);
         avx2_available_ = (cpuInfo[1] & 0x00000020) != 0;
-        avx512F_available_ = (cpuInfo[1] & 0x00010000) != 0;
-        avx512BW_available_ = (cpuInfo[1] & 0x40000000) != 0;
-        avx512VNNI_available_ = (cpuInfo[2] & 0x00000800) != 0;
+        if ((_xgetbv(0) & 0xe0) == 0xe0) {
+          // OS supports AVX512.
+          avx512F_available_ = (cpuInfo[1] & 0x00010000) != 0;
+          avx512BW_available_ = (cpuInfo[1] & 0x40000000) != 0;
+          avx512VNNI_available_ = (cpuInfo[2] & 0x00000800) != 0;
+	}
       }
 #      endif
     }