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Refactor bitscan64 check

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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.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@290924 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Saleem Abdulrasool
2017-01-04 01:53:24 +00:00
parent dcac520ce4
commit 5c737d8395
2 changed files with 5 additions and 3 deletions
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3
include/__config
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@@ -173,6 +173,9 @@
# ifndef __MINGW32__ # ifndef __MINGW32__
# define _LIBCPP_MSVCRT // Using Microsoft's C Runtime library # define _LIBCPP_MSVCRT // Using Microsoft's C Runtime library
# endif # endif
# if (defined(_M_AMD64) || defined(__x86_64__)) || (defined(_M_ARM) || defined(__arm__))
# define _LIBCPP_HAS_BITSCAN64
# endif
#endif // defined(_WIN32) #endif // defined(_WIN32)
#ifdef __sun__ #ifdef __sun__

5
include/support/win32/support.h
View File

@@ -110,7 +110,7 @@ _LIBCPP_ALWAYS_INLINE int __builtin_ctzll(unsigned long long mask)
unsigned long where; unsigned long where;
// Search from LSB to MSB for first set bit. // Search from LSB to MSB for first set bit.
// Returns zero if no set bit is found. // 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__)) (defined(_M_AMD64) || defined(__x86_64__))
if (_BitScanForward64(&where, mask)) if (_BitScanForward64(&where, mask))
return static_cast<int>(where); return static_cast<int>(where);
@@ -151,8 +151,7 @@ _LIBCPP_ALWAYS_INLINE int __builtin_clzll(unsigned long long mask)
unsigned long where; unsigned long where;
// BitScanReverse scans from MSB to LSB for first set bit. // BitScanReverse scans from MSB to LSB for first set bit.
// Returns 0 if no set bit is found. // Returns 0 if no set bit is found.
#if (defined(_M_ARM) || defined(__arm__)) || \ #if defined(_LIBCPP_HAS_BITSCAN64)
(defined(_M_AMD64) || defined(__x86_64__))
if (_BitScanReverse64(&where, mask)) if (_BitScanReverse64(&where, mask))
return static_cast<int>(63 - where); return static_cast<int>(63 - where);
#else #else