x86/cpu: implement get/set_eflags using intrinsics

Signed-off-by: Diego Biurrun <diego@biurrun.de>
Signed-off-by: Martin Storsjö <martin@martin.st>

configure

@@ -1126,6 +1126,7 @@ HAVE_LIST="
     rdtsc
     round
     roundf
+    rweflags
     sched_getaffinity
     sdl
     sdl_video_size
@@ -2747,6 +2748,7 @@ elif enabled x86; then
     check_code ld immintrin.h "__xgetbv(0)" && enable xgetbv
     check_code ld intrin.h "int info[4]; __cpuid(info, 0)" && enable cpuid
     check_code ld intrin.h "__rdtsc()" && enable rdtsc
+    check_code ld intrin.h "unsigned int x = __readeflags()" && enable rweflags
 
     check_code ld mmintrin.h "_mm_empty()" && enable mm_empty
 

libavutil/x86/cpu.c

@@ -62,6 +62,8 @@
     } while (0)
 #endif /* HAVE_XGETBV */
 
+#if HAVE_INLINE_ASM
+
 #define get_eflags(x)                           \
     __asm__ volatile ("pushfl     \n"           \
                       "pop    %0  \n"           \
@@ -72,6 +74,18 @@
                       "popfl      \n"           \
                       :: "r"(x))
 
+#elif HAVE_RWEFLAGS
+
+#include <intrin.h>
+
+#define get_eflags(x)                           \
+    x = __readeflags()
+
+#define set_eflags(x)                           \
+    __writeeflags(x)
+
+#endif /* HAVE_INLINE_ASM */
+
 /* Function to test if multimedia instructions are supported...  */
 int ff_get_cpu_flags_x86(void)
 {