mesa/x86: Support SSE 4.1 detection on x86-64.

Uses the cpuid.h header provided by gcc and clang. Other platforms are
encouraged to switch.

src/mesa/main/cpuinfo.c

@@ -34,7 +34,7 @@
 void
 _mesa_get_cpu_features(void)
 {
-#ifdef USE_X86_ASM
+#if defined USE_X86_ASM || (defined __x86_64__ && !defined _MSC_VER)
    _mesa_get_x86_features();
 #endif
 }

src/mesa/main/cpuinfo.h

@@ -27,7 +27,7 @@
 #define CPUINFO_H
 
 
-#if defined(USE_X86_ASM)
+#if defined USE_X86_ASM || (defined __x86_64__ && !defined _MSC_VER)
 #include "x86/common_x86_asm.h"
 #endif
 

src/mesa/x86/common_x86.c

@@ -47,6 +47,9 @@
 #include <sys/sysctl.h>
 #include <machine/cpu.h>
 #endif
+#if defined(__x86_64__) && !defined(_MSC_VER)
+#include <cpuid.h>
+#endif
 
 #include "main/imports.h"
 #include "common_x86_asm.h"
@@ -330,6 +333,14 @@ _mesa_get_x86_features(void)
    }
 #endif
 
+#elif defined(__x86_64__) && !defined(_MSC_VER)
+   unsigned int uninitialized_var(eax), uninitialized_var(ebx),
+                uninitialized_var(ecx), uninitialized_var(edx);
+
+   /* Always available on x86-64. */
+   _mesa_x86_cpu_features |= X86_FEATURE_XMM | X86_FEATURE_XMM2;
+
+   __get_cpuid(1, &eax, &ebx, &ecx, &edx);
 #endif /* USE_X86_ASM */
 
    (void) detection_debug;