[Bf-blender-cvs] [ef73d54] master: Fix T38815

[Martijn Berger]

Commit: ef73d547cc7c663ad180721094c81b3c81482ac3
Author: Martijn Berger
Date:   Tue Feb 25 17:57:05 2014 +0100
https://developer.blender.org/rBef73d547cc7c663ad180721094c81b3c81482ac3

Fix T38815

For AVX support we need to check both OS support and CPU support.

===================================================================

M	intern/cycles/util/util_system.cpp

===================================================================

diff --git a/intern/cycles/util/util_system.cpp b/intern/cycles/util/util_system.cpp
index 3d7781f..c489862 100644
--- a/intern/cycles/util/util_system.cpp
+++ b/intern/cycles/util/util_system.cpp
@@ -161,8 +161,24 @@ static CPUCapabilities& system_cpu_capabilities()
 			caps.sse41 = (result[2] & ((int)1 << 19)) != 0;
 			caps.sse42 = (result[2] & ((int)1 << 20)) != 0;
 
-			caps.avx = (result[2] & ((int)1 << 28)) != 0;
 			caps.fma3 = (result[2] & ((int)1 << 12)) != 0;
+			caps.avx = false;
+			bool os_uses_xsave_xrestore = result[2] & ((int)1 << 27) != 0;
+			bool cpu_avx_support = (result[2] & ((int)1 << 28)) != 0;
+
+			if( os_uses_xsave_xrestore && cpu_avx_support) {
+				// Check if the OS will save the YMM registers
+				uint32_t xcr_feature_mask;
+				#if defined(__GNUC__)
+					int edx; // not used
+					__asm__ (".byte 0x0f, 0x01, 0xd0" : "=a" (xcr_feature_mask) , "=d" (edx) : "c" (0) ); /* actual opcode for xgetbv */
+				#elif defined(_MSC_VER) && defined(_XCR_XFEATURE_ENABLED_MASK)
+					xcr_feature_mask = (uint32_t)_xgetbv(_XCR_XFEATURE_ENABLED_MASK);  /* min VS2010 SP1 compiler is required */
+				#else
+					xcr_feature_mask = 0;
+				#endif
+				caps.avx = (xcr_feature_mask & 0x6) == 0x6;
+			}
 		}
 
 #if 0