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-rw-r--r--src/crypto/sha256.cpp21
1 files changed, 17 insertions, 4 deletions
diff --git a/src/crypto/sha256.cpp b/src/crypto/sha256.cpp
index 100d0d1fac..e62ddc125e 100644
--- a/src/crypto/sha256.cpp
+++ b/src/crypto/sha256.cpp
@@ -536,6 +536,14 @@ void inline cpuid(uint32_t leaf, uint32_t subleaf, uint32_t& a, uint32_t& b, uin
{
__asm__ ("cpuid" : "=a"(a), "=b"(b), "=c"(c), "=d"(d) : "0"(leaf), "2"(subleaf));
}
+
+/** Check whether the OS has enabled AVX registers. */
+bool AVXEnabled()
+{
+ uint32_t a, d;
+ __asm__("xgetbv" : "=a"(a), "=d"(d) : "c"(0));
+ return (a & 6) == 6;
+}
#endif
} // namespace
@@ -544,6 +552,7 @@ std::string SHA256AutoDetect()
{
std::string ret = "standard";
#if defined(USE_ASM) && (defined(__x86_64__) || defined(__amd64__) || defined(__i386__))
+ (void)AVXEnabled; // Silence unused warning (in case ENABLE_AVX2 is not defined)
uint32_t eax, ebx, ecx, edx;
cpuid(1, 0, eax, ebx, ecx, edx);
if ((ecx >> 19) & 1) {
@@ -555,10 +564,14 @@ std::string SHA256AutoDetect()
TransformD64_4way = sha256d64_sse41::Transform_4way;
ret = "sse4(1way+4way)";
#if defined(ENABLE_AVX2) && !defined(BUILD_BITCOIN_INTERNAL)
- cpuid(7, 0, eax, ebx, ecx, edx);
- if ((ebx >> 5) & 1) {
- TransformD64_8way = sha256d64_avx2::Transform_8way;
- ret += ",avx2(8way)";
+ if (((ecx >> 27) & 1) && ((ecx >> 28) & 1)) { // XSAVE and AVX
+ cpuid(7, 0, eax, ebx, ecx, edx);
+ if ((ebx >> 5) & 1) { // AVX2 flag
+ if (AVXEnabled()) { // OS has enabled AVX registers
+ TransformD64_8way = sha256d64_avx2::Transform_8way;
+ ret += ",avx2(8way)";
+ }
+ }
}
#endif
#else