[libcxx] r290924 - Refactor bitscan64 check

[Saleem Abdulrasool via cfe-commits]

Author: compnerd
Date: Tue Jan  3 19:53:24 2017
New Revision: 290924

URL: http://llvm.org/viewvc/llvm-project?rev=290924&view=rev
Log:
Refactor bitscan64 check

Introduce a `_LIBCPP_HAS_BITSCAN64` macro to specify if the 64-bit
variant of the bitscan family of APIs is available.  This avoids
duplicating the check in the support header.

Modified:
    libcxx/trunk/include/__config
    libcxx/trunk/include/support/win32/support.h

Modified: libcxx/trunk/include/__config
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/__config?rev=290924&r1=290923&r2=290924&view=diff
==============================================================================
--- libcxx/trunk/include/__config (original)
+++ libcxx/trunk/include/__config Tue Jan  3 19:53:24 2017
@@ -173,6 +173,9 @@
 #  ifndef __MINGW32__
 #    define _LIBCPP_MSVCRT // Using Microsoft's C Runtime library
 #  endif
+#  if (defined(_M_AMD64) || defined(__x86_64__)) || (defined(_M_ARM) || defined(__arm__))
+#    define _LIBCPP_HAS_BITSCAN64
+#  endif
 #endif // defined(_WIN32)
 
 #ifdef __sun__

Modified: libcxx/trunk/include/support/win32/support.h
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/support/win32/support.h?rev=290924&r1=290923&r2=290924&view=diff
==============================================================================
--- libcxx/trunk/include/support/win32/support.h (original)
+++ libcxx/trunk/include/support/win32/support.h Tue Jan  3 19:53:24 2017
@@ -110,7 +110,7 @@ _LIBCPP_ALWAYS_INLINE int __builtin_ctzl
   unsigned long where;
 // Search from LSB to MSB for first set bit.
 // Returns zero if no set bit is found.
-#if (defined(_M_ARM) || defined(__arm__)) ||                                   \
+#if defined(_LIBCPP_HAS_BITSCAN64)
     (defined(_M_AMD64) || defined(__x86_64__))
   if (_BitScanForward64(&where, mask))
     return static_cast<int>(where);
@@ -151,8 +151,7 @@ _LIBCPP_ALWAYS_INLINE int __builtin_clzl
   unsigned long where;
 // BitScanReverse scans from MSB to LSB for first set bit.
 // Returns 0 if no set bit is found.
-#if (defined(_M_ARM) || defined(__arm__)) ||                                   \
-    (defined(_M_AMD64) || defined(__x86_64__))
+#if defined(_LIBCPP_HAS_BITSCAN64)
   if (_BitScanReverse64(&where, mask))
     return static_cast<int>(63 - where);
 #else