---
I've changed this patch slightly because I discovered that it would cause an
illegal instruction exception on much older processors (probably all without
AVX). I was running xgetbv() almost uncontitionally. Now it is a little more
like what is the in x264 patch.
libavutil/x86/cpu.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/libavutil/x86/cpu.c b/libavutil/x86/cpu.c
index f33088c8c7..589fdef7da 100644
--- a/libavutil/x86/cpu.c
+++ b/libavutil/x86/cpu.c
@@ -97,6 +97,7 @@ int ff_get_cpu_flags_x86(void)
int max_std_level, max_ext_level, std_caps = 0, ext_caps = 0;
int family = 0, model = 0;
union { int i[3]; char c[12]; } vendor;
+ int xcr0_lo = 0, xcr0_hi = 0;
if (!cpuid_test())
return 0; /* CPUID not supported */
@@ -132,8 +133,8 @@ int ff_get_cpu_flags_x86(void)
/* Check OXSAVE and AVX bits */
if ((ecx & 0x18000000) == 0x18000000) {
/* Check for OS support */
- xgetbv(0, eax, edx);
- if ((eax & 0x6) == 0x6) {
+ xgetbv(0, xcr0_lo, xcr0_hi);
+ if ((xcr0_lo & 0x6) == 0x6) {
rval |= AV_CPU_FLAG_AVX;
if (ecx & 0x00001000)
rval |= AV_CPU_FLAG_FMA3;
@@ -154,6 +155,13 @@ int ff_get_cpu_flags_x86(void)
if (ebx & 0x00000100)
rval |= AV_CPU_FLAG_BMI2;
}
+#if HAVE_AVX512 /* F, CD, BW, DQ, VL */
+ if ((xcr0_lo & 0xe6) == 0xe6) {
+ if ((ebx & 0xd0030000) == 0xd0030000)
+ rval |= AV_CPU_FLAG_AVX512;
+
+ }
+#endif
}
cpuid(0x80000000, max_ext_level, ebx, ecx, edx);
--
2.15.0
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