Fix for conflicting definition of _xgetbv with mingw-w64 >= 5

Simplify the #ifdef logic so it is easier to follow and add exceptions in the
future if necessary.

diff --git a/libs/pbd/fpu.cc b/libs/pbd/fpu.cc
index 7c3e0978812e28affd3cb68e661def7adf401484..78bcd3d8121f0f71e79cd3ebcc700124ae7f8eb9 100644 (file)
--- a/libs/pbd/fpu.cc
+++ b/libs/pbd/fpu.cc
@@ -71,24 +71,18 @@ __cpuid(int regs[4], int cpuid_leaf)
 
 #endif /* !PLATFORM_WINDOWS */
 
-#ifndef COMPILER_MSVC
-
-static uint64_t
-_xgetbv (uint32_t xcr)
-{
-#ifdef __APPLE__
-        /* it would be nice to make this work on OS X but as long we use veclib,
-           we don't really need to know about SSE/AVX on that platform.
-        */
-        return 0;
-#else
-       uint32_t eax, edx;
-       __asm__ volatile ("xgetbv" : "=a" (eax), "=d" (edx) : "c" (xcr));
-       return (static_cast<uint64_t>(edx) << 32) | eax;
+#ifndef HAVE_XGETBV // Allow definition by build system
+       #if defined(__MINGW32__) && defined(__MINGW64_VERSION_MAJOR) && __MINGW64_VERSION_MAJOR >= 5
+               #define HAVE_XGETBV
+       #elif defined(_MSC_VER) && _MSC_VER >= 1600
+               // '_xgetbv()' was only available from VC10 onwards
+               #define HAVE_XGETBV
+       #endif
 #endif
-}
 
-#elif _MSC_VER < 1600
+#ifndef HAVE_XGETBV
+
+#ifdef COMPILER_MSVC
 
 // '_xgetbv()' was only available from VC10 onwards
 __declspec(noinline) static uint64_t
@@ -101,11 +95,29 @@ _xgetbv (uint32_t xcr)
        // to place this function into its own (unoptimized) source file.
        __asm {
                         mov ecx, [xcr]
-                        __asm _emit 0x0f __asm _emit 0x01 __asm _emit 0xd0   /*xgetbv*/
-                 }
+                        __asm _emit 0x0f __asm _emit 0x01 __asm _emit 0xd0 /*xgetbv*/
+       }
+}
+
+#else
+
+static uint64_t
+_xgetbv (uint32_t xcr)
+{
+#ifdef __APPLE__
+       /* it would be nice to make this work on OS X but as long we use veclib,
+          we don't really need to know about SSE/AVX on that platform.
+       */
+       return 0;
+#else
+       uint32_t eax, edx;
+       __asm__ volatile ("xgetbv" : "=a" (eax), "=d" (edx) : "c" (xcr));
+       return (static_cast<uint64_t>(edx) << 32) | eax;
+#endif
 }
 
 #endif /* !COMPILER_MSVC */
+#endif /* !HAVE_XGETBV */
 #endif /* ARCH_X86 */
 
 #ifndef _XCR_XFEATURE_ENABLED_MASK