[libc++] Refactor Windows support headers.

[EricWF]

Summary

This patch refactors and tries to remove as much of the Windows support headers as possible. This is needed because they currently introduce super weird include cycles and dependencies between STL and libc headers.

The changes in this patch are:

• remove support/win32/support.h completely. The required parts have either been moved into support/win32/msvc_support.h (for MSVC only helpers not needed by Clang), or directly into their respective foo.h headers.

• Combine locale_win32.h and locale_mgmt_win32.h into a single headers, this header should only be included within __locale or locale to avoid include cycles.

• Remove the unneeded parts of limits_win32.h and re-name it to limits_msvc_win32.h since it's only needed by Clang.

I've tested this patch using Clang on Windows, but I suspect it might technically regress our non-existent support for MSVC. Is somebody able to double check?

This refactor is needed to support upcoming fixes to <locale> on Windows.

[EricWF]

• Rename msvc_support.h to msvc_builtin_support.h.

[EricWF]

This breaks MinGW. I'll update soon.

include/algorithm

647–648

This change is incorrect too.

include/limits

114–115

This is incorrect for MinGW.

[bcraig]

include/__config

232–235

I can see this helping when we are build libc++, but I don't think it helps client apps. They could have included windows.h before including our headers.

Don't get me wrong, I dislike the min and max macros, and bear no hard feelings towards people that define this project wide on the command line, I'm just not sure it will get things done right here.

In the past, I've just surrounded my min and max declarations with parenthesis to suppress macro expansion.

[compnerd]

include/__config

232–235

Yeah, I don't think that this should be defined in __config. Can we do something like #pragma push_macro and #pragma pop_macro in the necessary files?

include/stdio.h

113–118

Should this be hoisted above the #ifdef __cplusplus? This seems like it should be defined by stdio.h but isn't in msvcrt?

include/support/win32/locale_win32.h

24

Can you please clang-format this block?

include/support/win32/msvc_builtin_support.h

33–51 ↗

(On Diff #98246)

I think I prefer the following implementation:

_LIBCPP_ALWAYS_INLINE int __builtin_popcount(unsigned int value) {
  return __popcnt(value);
}

58–76 ↗

(On Diff #98246)

I think I prefer the following implementation:

_LIBCPP_ALWAYS_INLINE int __builtin_popcountll(unsigned long long value) {
  return __popcnt64(value);
}

src/string.cpp

430

This seems scary. Why do we need to cast the function?

[majnemer]

include/support/win32/msvc_builtin_support.h

33 ↗

(On Diff #98246)

I think it'd be better not to call it __builtin_anything. MSVC uses the __builtin_ namespace too, see https://godbolt.org/g/HwMskX

Maybe create a wrapper called __libcpp_popcount?

[EricWF]

include/__config

232–235

Alright I'll remove the NOMINMAX define in __config and start to sprinkle the __undef_min_max include where it's currently needed.

@compnerd, using push_macro and pop_macro are going to be the correct way to handle this, but that's a change for another patch.

include/support/win32/msvc_builtin_support.h

33 ↗

(On Diff #98246)

That's a change for another patch, one that's just meant to restructure the headers.

This patch simply moves this code to another file.

33–51 ↗

(On Diff #98246)

That's a change for another patch, one that's just meant to restructure the headers.

This patch simply moves this code to another file.

src/string.cpp

430

No idea.

[EricWF]

• General cleanup changes.

Libc++ trunk currently doesn't build under MinGW, so I'm not concerned about breaking that worse with this patch. I've set up a Appveyor builder to track MinGW so we can get it green later.

Also I'm planning on making all of the the changes suggested in inline comments, but in a follow up patch. I would like to keep this to simply renaming and restructuring include files.
With that in mind does anybody object to landing this?

[bcraig]

LGTM

[EricWF]

@compnerd I'm going to go ahead and land this and then submit a separate review for the changes you've requested. I hope you don't mind :-)

include/__config

 #  endif
 #  if (defined(_M_AMD64) || defined(__x86_64__)) || (defined(_M_ARM) || defined(__arm__))
 #    define _LIBCPP_HAS_BITSCAN64
 #  endif
 # if defined(_LIBCPP_MSVCRT)
 #   define _LIBCPP_HAS_QUICK_EXIT
 # endif
 
+#ifndef NOMINMAX
+#define NOMINMAX
+#endif
+
 // Some CRT APIs are unavailable to store apps
 #if defined(WINAPI_FAMILY)
 #include <winapifamily.h>
 #if !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP) &&                      \
     (!defined(WINAPI_PARTITION_SYSTEM) ||                                      \
      !WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_SYSTEM))
 #define _LIBCPP_WINDOWS_STORE_APP
 #endif

include/algorithm

 #include <utility> // needed to provide swap_ranges.
 #include <memory>
 #include <iterator>
 #include <cstddef>
 
 #if defined(__IBMCPP__)
 #include "support/ibm/support.h"
 #endif
-#if defined(_LIBCPP_MSVCRT) || defined(__MINGW32__)
-#include "support/win32/support.h"
+#if defined(_LIBCPP_COMPILER_MSVC)
+#include "support/win32/msvc_support.h"
 #endif
 
 #include <__undef_min_max>
 
 #include <__debug>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header

include/ctype.h

 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 #include_next <ctype.h>
 
 #ifdef __cplusplus
 
-#if defined(_LIBCPP_MSVCRT)
-// We support including .h headers inside 'extern "C"' contexts, so switch
-// back to C++ linkage before including these C++ headers.
-extern "C++" {
-  #include "support/win32/support.h"
-  #include "support/win32/locale_win32.h"
-}
-#endif // _LIBCPP_MSVCRT
-
 #undef isalnum
 #undef isalpha
 #undef isblank
 #undef iscntrl
 #undef isdigit
 #undef isgraph
 #undef islower
 #undef isprint

include/limits

 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
 #endif
 
 #include <type_traits>
 
 #include <__undef_min_max>
 
-#if defined(_LIBCPP_MSVCRT)
-#include "support/win32/limits_win32.h"
+#if defined(_LIBCPP_COMPILER_MSVC)
+#include "support/win32/limits_msvc_win32.h"
 #endif // _LIBCPP_MSVCRT
 
 #if defined(__IBMCPP__)
 #include "support/ibm/limits.h"
 #endif // __IBMCPP__
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 

include/stdio.h

 #pragma GCC system_header
 #endif
 
 #include_next <stdio.h>
 
 #ifdef __cplusplus
 
 // snprintf
 #if defined(_LIBCPP_MSVCRT)
-extern "C++" {
-#include "support/win32/support.h"
+extern "C" {
+int vasprintf(char **sptr, const char *__restrict fmt, va_list ap);
+int asprintf(char **sptr, const char *__restrict fmt, ...);
 }
 #endif
 
 #undef getc
 #undef putc
 #undef clearerr
 #undef feof
 #undef ferror
 
 #endif
 
 #endif  // _LIBCPP_STDIO_H

include/stdlib.h

 #endif
 
 #include_next <stdlib.h>
 
 #ifdef __cplusplus
 
 extern "C++" {
 
-#ifdef _LIBCPP_MSVCRT
-#include "support/win32/locale_win32.h"
-#endif // _LIBCPP_MSVCRT
-
 #undef abs
 #undef div
 #undef labs
 #undef ldiv
 #ifndef _LIBCPP_HAS_NO_LONG_LONG
 #undef llabs
 #undef lldiv
 #endif

include/support/win32/limits_msvc_win32.h

+// -*- C++ -*-
+//===------------------ support/win32/limits_msvc_win32.h -----------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_SUPPORT_WIN32_LIMITS_MSVC_WIN32_H
+#define _LIBCPP_SUPPORT_WIN32_LIMITS_MSVC_WIN32_H
+
+#if !defined(_LIBCPP_MSVCRT)
+#error "This header complements the Microsoft C Runtime library, and should not be included otherwise."
+#endif
+#if defined(__clang__)
+#error "This header should only be included when using Microsofts C1XX frontend"
+#endif
+
+#include <limits.h> // CHAR_BIT
+#include <float.h> // limit constants
+#include <math.h> // HUGE_VAL
+#include <ymath.h> // internal MSVC header providing the needed functionality
+
+#define __CHAR_BIT__       CHAR_BIT
+
+#define __FLT_MANT_DIG__   FLT_MANT_DIG
+#define __FLT_DIG__        FLT_DIG
+#define __FLT_RADIX__      FLT_RADIX
+#define __FLT_MIN_EXP__    FLT_MIN_EXP
+#define __FLT_MIN_10_EXP__ FLT_MIN_10_EXP
+#define __FLT_MAX_EXP__    FLT_MAX_EXP
+#define __FLT_MAX_10_EXP__ FLT_MAX_10_EXP
+#define __FLT_MIN__        FLT_MIN
+#define __FLT_MAX__        FLT_MAX
+#define __FLT_EPSILON__    FLT_EPSILON
+// predefined by MinGW GCC
+#define __FLT_DENORM_MIN__ 1.40129846432481707092e-45F
+
+#define __DBL_MANT_DIG__   DBL_MANT_DIG
+#define __DBL_DIG__        DBL_DIG
+#define __DBL_RADIX__      DBL_RADIX
+#define __DBL_MIN_EXP__    DBL_MIN_EXP
+#define __DBL_MIN_10_EXP__ DBL_MIN_10_EXP
+#define __DBL_MAX_EXP__    DBL_MAX_EXP
+#define __DBL_MAX_10_EXP__ DBL_MAX_10_EXP
+#define __DBL_MIN__        DBL_MIN
+#define __DBL_MAX__        DBL_MAX
+#define __DBL_EPSILON__    DBL_EPSILON
+// predefined by MinGW GCC
+#define __DBL_DENORM_MIN__ double(4.94065645841246544177e-324L)
+
+#define __LDBL_MANT_DIG__   LDBL_MANT_DIG
+#define __LDBL_DIG__        LDBL_DIG
+#define __LDBL_RADIX__      LDBL_RADIX
+#define __LDBL_MIN_EXP__    LDBL_MIN_EXP
+#define __LDBL_MIN_10_EXP__ LDBL_MIN_10_EXP
+#define __LDBL_MAX_EXP__    LDBL_MAX_EXP
+#define __LDBL_MAX_10_EXP__ LDBL_MAX_10_EXP
+#define __LDBL_MIN__        LDBL_MIN
+#define __LDBL_MAX__        LDBL_MAX
+#define __LDBL_EPSILON__    LDBL_EPSILON
+// predefined by MinGW GCC
+#define __LDBL_DENORM_MIN__ 3.64519953188247460253e-4951L
+
+// __builtin replacements/workarounds
+#define __builtin_huge_vall()    _LInf._Long_double
+#define __builtin_nanl(__dummmy) _LNan._Long_double
+#define __builtin_nansl(__dummy) _LSnan._Long_double
+
+#endif // _LIBCPP_SUPPORT_WIN32_LIMITS_MSVC_WIN32_H

include/support/win32/limits_win32.h

-// -*- C++ -*-
-//===--------------------- support/win32/limits_win32.h -------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is dual licensed under the MIT and the University of Illinois Open
-// Source Licenses. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _LIBCPP_SUPPORT_WIN32_LIMITS_WIN32_H
-#define _LIBCPP_SUPPORT_WIN32_LIMITS_WIN32_H
-
-#if !defined(_LIBCPP_MSVCRT)
-#error "This header complements the Microsoft C Runtime library, and should not be included otherwise."
-#else
-
-#include <limits.h> // CHAR_BIT
-#include <float.h> // limit constants
-
-#if ! defined(__clang__)
-#define __CHAR_BIT__       CHAR_BIT
-
-#define __FLT_MANT_DIG__   FLT_MANT_DIG
-#define __FLT_DIG__        FLT_DIG
-#define __FLT_RADIX__      FLT_RADIX
-#define __FLT_MIN_EXP__    FLT_MIN_EXP
-#define __FLT_MIN_10_EXP__ FLT_MIN_10_EXP
-#define __FLT_MAX_EXP__    FLT_MAX_EXP
-#define __FLT_MAX_10_EXP__ FLT_MAX_10_EXP
-#define __FLT_MIN__        FLT_MIN
-#define __FLT_MAX__        FLT_MAX
-#define __FLT_EPSILON__    FLT_EPSILON
-// predefined by MinGW GCC
-#define __FLT_DENORM_MIN__ 1.40129846432481707092e-45F
-
-#define __DBL_MANT_DIG__   DBL_MANT_DIG
-#define __DBL_DIG__        DBL_DIG
-#define __DBL_RADIX__      DBL_RADIX
-#define __DBL_MIN_EXP__    DBL_MIN_EXP
-#define __DBL_MIN_10_EXP__ DBL_MIN_10_EXP
-#define __DBL_MAX_EXP__    DBL_MAX_EXP
-#define __DBL_MAX_10_EXP__ DBL_MAX_10_EXP
-#define __DBL_MIN__        DBL_MIN
-#define __DBL_MAX__        DBL_MAX
-#define __DBL_EPSILON__    DBL_EPSILON
-// predefined by MinGW GCC
-#define __DBL_DENORM_MIN__ double(4.94065645841246544177e-324L)
-
-#define __LDBL_MANT_DIG__   LDBL_MANT_DIG
-#define __LDBL_DIG__        LDBL_DIG
-#define __LDBL_RADIX__      LDBL_RADIX
-#define __LDBL_MIN_EXP__    LDBL_MIN_EXP
-#define __LDBL_MIN_10_EXP__ LDBL_MIN_10_EXP
-#define __LDBL_MAX_EXP__    LDBL_MAX_EXP
-#define __LDBL_MAX_10_EXP__ LDBL_MAX_10_EXP
-#define __LDBL_MIN__        LDBL_MIN
-#define __LDBL_MAX__        LDBL_MAX
-#define __LDBL_EPSILON__    LDBL_EPSILON
-// predefined by MinGW GCC
-#define __LDBL_DENORM_MIN__ 3.64519953188247460253e-4951L
-
-// __builtin replacements/workarounds
-#include <math.h> // HUGE_VAL
-#include <ymath.h> // internal MSVC header providing the needed functionality
-#define __builtin_huge_val()     HUGE_VAL
-#define __builtin_huge_valf()    _FInf._Float
-#define __builtin_huge_vall()    _LInf._Long_double
-#define __builtin_nan(__dummy)   _Nan._Double
-#define __builtin_nanf(__dummy)  _FNan._Float
-#define __builtin_nanl(__dummmy) _LNan._Long_double
-#define __builtin_nans(__dummy)  _Snan._Double
-#define __builtin_nansf(__dummy) _FSnan._Float
-#define __builtin_nansl(__dummy) _LSnan._Long_double
-#endif // ! defined(__clang__)
-
-#endif // _LIBCPP_MSVCRT
-
-#endif // _LIBCPP_SUPPORT_WIN32_LIMITS_WIN32_H

include/support/win32/locale_mgmt_win32.h

-// -*- C++ -*-
-//===----------------- support/win32/locale_mgmt_win32.h ------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is dual licensed under the MIT and the University of Illinois Open
-// Source Licenses. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _LIBCPP_SUPPORT_WIN32_LOCALE_MGMT_WIN32_H
-#define _LIBCPP_SUPPORT_WIN32_LOCALE_MGMT_WIN32_H
-
-#include <xlocinfo.h> // _locale_t
-#define locale_t _locale_t
-#define LC_COLLATE_MASK _M_COLLATE
-#define LC_CTYPE_MASK _M_CTYPE
-#define LC_MONETARY_MASK _M_MONETARY
-#define LC_NUMERIC_MASK _M_NUMERIC
-#define LC_TIME_MASK _M_TIME
-#define LC_MESSAGES_MASK _M_MESSAGES
-#define LC_ALL_MASK (  LC_COLLATE_MASK \
-                     | LC_CTYPE_MASK \
-                     | LC_MESSAGES_MASK \
-                     | LC_MONETARY_MASK \
-                     | LC_NUMERIC_MASK \
-                     | LC_TIME_MASK )
-#define freelocale _free_locale
-// FIXME: base currently unused. Needs manual work to construct the new locale
-locale_t newlocale( int mask, const char * locale, locale_t base );
-locale_t uselocale( locale_t newloc );
-
-#endif // _LIBCPP_SUPPORT_WIN32_LOCALE_MGMT_WIN32_H

include/support/win32/locale_win32.h

 // -*- C++ -*-
 //===--------------------- support/win32/locale_win32.h -------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef _LIBCPP_SUPPORT_WIN32_LOCALE_WIN32_H
 #define _LIBCPP_SUPPORT_WIN32_LOCALE_WIN32_H
 
 #include <__config>
-#include "support/win32/support.h"
-#include "support/win32/locale_mgmt_win32.h"
 #include <stdio.h>
+#include <xlocinfo.h> // _locale_t
+
+#define LC_COLLATE_MASK _M_COLLATE
+#define LC_CTYPE_MASK _M_CTYPE
+#define LC_MONETARY_MASK _M_MONETARY
+#define LC_NUMERIC_MASK _M_NUMERIC
+#define LC_TIME_MASK _M_TIME
+#define LC_MESSAGES_MASK _M_MESSAGES
+#define LC_ALL_MASK (  LC_COLLATE_MASK \
+                     | LC_CTYPE_MASK \
+                     | LC_MESSAGES_MASK \
+                     | LC_MONETARY_MASK \
+                     | LC_NUMERIC_MASK \
+                     | LC_TIME_MASK )
+
+#define locale_t _locale_t
+
+// Locale management functions
+#define freelocale _free_locale
+// FIXME: base currently unused. Needs manual work to construct the new locale
+locale_t newlocale( int mask, const char * locale, locale_t base );
+locale_t uselocale( locale_t newloc );
+
 
 lconv *localeconv_l( locale_t loc );
 size_t mbrlen_l( const char *__restrict s, size_t n,
                  mbstate_t *__restrict ps, locale_t loc);
 size_t mbsrtowcs_l( wchar_t *__restrict dst, const char **__restrict src,
                     size_t len, mbstate_t *__restrict ps, locale_t loc );
 size_t wcrtomb_l( char *__restrict s, wchar_t wc, mbstate_t *__restrict ps,
                   locale_t loc);

 #define vsscanf_l( __s, __l, __f, ...) _sscanf_l( __s, __f, __l, __VA_ARGS__ )
 #define sprintf_l( __s, __l, __f, ... ) _sprintf_l( __s, __f, __l, __VA_ARGS__ )
 #define vsprintf_l( __s, __l, __f, ... ) _vsprintf_l( __s, __f, __l, __VA_ARGS__ )
 #define vsnprintf_l( __s, __n, __l, __f, ... ) _vsnprintf_l( __s, __n, __f, __l, __VA_ARGS__ )
 _LIBCPP_FUNC_VIS int snprintf_l(char *ret, size_t n, locale_t loc, const char *format, ...);
 _LIBCPP_FUNC_VIS int asprintf_l( char **ret, locale_t loc, const char *format, ... );
 _LIBCPP_FUNC_VIS int vasprintf_l( char **ret, locale_t loc, const char *format, va_list ap );
 
-
 // not-so-pressing FIXME: use locale to determine blank characters
 inline int isblank_l( int c, locale_t /*loc*/ )
 {
     return ( c == ' ' || c == '\t' );
 }
 inline int iswblank_l( wint_t c, locale_t /*loc*/ )
 {
     return ( c == L' ' || c == L'\t' );
 }
 
-#if defined(_LIBCPP_MSVCRT)
-inline int isblank( int c, locale_t /*loc*/ )
-{ return ( c == ' ' || c == '\t' ); }
-inline int iswblank( wint_t c, locale_t /*loc*/ )
-{ return ( c == L' ' || c == L'\t' ); }
-#endif // _LIBCPP_MSVCRT
 #endif // _LIBCPP_SUPPORT_WIN32_LOCALE_WIN32_H

include/support/win32/msvc_support.h

+// -*- C++ -*-
+//===----------------------- support/win32/support.h ----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_SUPPORT_WIN32_MSVC_SUPPORT_H
+#define _LIBCPP_SUPPORT_WIN32_MSVC_SUPPORT_H
+
+#ifndef _LIBCPP_COMPILER_MSVC
+#error "This header can only be included when using Microsoft's C1XX frontend"
+#endif
+
+#ifndef NOMINMAX
+#define NOMINMAX
+#endif
+
+// "builtins" not implemented here for Clang or GCC as they provide
+// implementations. Assuming required for elsewhere else, certainly MSVC.
+#include <intrin.h>
+
+// Bit builtin's make these assumptions when calling _BitScanForward/Reverse
+// etc. These assumptions are expected to be true for Win32/Win64 which this
+// file supports.
+static_assert(sizeof(unsigned long long) == 8, "");
+static_assert(sizeof(unsigned long) == 4, "");
+static_assert(sizeof(unsigned int) == 4, "");
+
+_LIBCPP_ALWAYS_INLINE int __builtin_popcount(unsigned int x)
+{
+  // Binary: 0101...
+  static const unsigned int m1 = 0x55555555;
+  // Binary: 00110011..
+  static const unsigned int m2 = 0x33333333;
+  // Binary:  4 zeros,  4 ones ...
+  static const unsigned int m4 = 0x0f0f0f0f;
+  // The sum of 256 to the power of 0,1,2,3...
+  static const unsigned int h01 = 0x01010101;
+  // Put count of each 2 bits into those 2 bits.
+  x -= (x >> 1) & m1;
+  // Put count of each 4 bits into those 4 bits.
+  x = (x & m2) + ((x >> 2) & m2);
+  // Put count of each 8 bits into those 8 bits.
+  x = (x + (x >> 4)) & m4;
+  // Returns left 8 bits of x + (x<<8) + (x<<16) + (x<<24).
+  return (x * h01) >> 24;
+}
+
+_LIBCPP_ALWAYS_INLINE int __builtin_popcountl(unsigned long x)
+{
+  return __builtin_popcount(static_cast<int>(x));
+}
+
+_LIBCPP_ALWAYS_INLINE int __builtin_popcountll(unsigned long long x)
+{
+  // Binary: 0101...
+  static const unsigned long long m1 = 0x5555555555555555;
+  // Binary: 00110011..
+  static const unsigned long long m2 = 0x3333333333333333;
+  // Binary:  4 zeros,  4 ones ...
+  static const unsigned long long m4 = 0x0f0f0f0f0f0f0f0f;
+  // The sum of 256 to the power of 0,1,2,3...
+  static const unsigned long long h01 = 0x0101010101010101;
+  // Put count of each 2 bits into those 2 bits.
+  x -= (x >> 1) & m1;
+  // Put count of each 4 bits into those 4 bits.
+  x = (x & m2) + ((x >> 2) & m2);
+  // Put count of each 8 bits into those 8 bits.
+  x = (x + (x >> 4)) & m4;
+  // Returns left 8 bits of x + (x<<8) + (x<<16) + (x<<24) + ...
+  return static_cast<int>((x * h01) >> 56);
+}
+
+// Returns the number of trailing 0-bits in x, starting at the least significant
+// bit position. If x is 0, the result is undefined.
+_LIBCPP_ALWAYS_INLINE int __builtin_ctzll(unsigned long long mask)
+{
+  unsigned long where;
+// Search from LSB to MSB for first set bit.
+// Returns zero if no set bit is found.
+#if defined(_LIBCPP_HAS_BITSCAN64)
+    (defined(_M_AMD64) || defined(__x86_64__))
+  if (_BitScanForward64(&where, mask))
+    return static_cast<int>(where);
+#else
+  // Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
+  // Scan the Low Word.
+  if (_BitScanForward(&where, static_cast<unsigned long>(mask)))
+    return static_cast<int>(where);
+  // Scan the High Word.
+  if (_BitScanForward(&where, static_cast<unsigned long>(mask >> 32)))
+    return static_cast<int>(where + 32); // Create a bit offset from the LSB.
+#endif
+  return 64;
+}
+
+_LIBCPP_ALWAYS_INLINE int __builtin_ctzl(unsigned long mask)
+{
+  unsigned long where;
+  // Search from LSB to MSB for first set bit.
+  // Returns zero if no set bit is found.
+  if (_BitScanForward(&where, mask))
+    return static_cast<int>(where);
+  return 32;
+}
+
+_LIBCPP_ALWAYS_INLINE int __builtin_ctz(unsigned int mask)
+{
+  // Win32 and Win64 expectations.
+  static_assert(sizeof(mask) == 4, "");
+  static_assert(sizeof(unsigned long) == 4, "");
+  return __builtin_ctzl(static_cast<unsigned long>(mask));
+}
+
+// Returns the number of leading 0-bits in x, starting at the most significant
+// bit position. If x is 0, the result is undefined.
+_LIBCPP_ALWAYS_INLINE int __builtin_clzll(unsigned long long mask)
+{
+  unsigned long where;
+// BitScanReverse scans from MSB to LSB for first set bit.
+// Returns 0 if no set bit is found.
+#if defined(_LIBCPP_HAS_BITSCAN64)
+  if (_BitScanReverse64(&where, mask))
+    return static_cast<int>(63 - where);
+#else
+  // Scan the high 32 bits.
+  if (_BitScanReverse(&where, static_cast<unsigned long>(mask >> 32)))
+    return static_cast<int>(63 -
+                            (where + 32)); // Create a bit offset from the MSB.
+  // Scan the low 32 bits.
+  if (_BitScanReverse(&where, static_cast<unsigned long>(mask)))
+    return static_cast<int>(63 - where);
+#endif
+  return 64; // Undefined Behavior.
+}
+
+_LIBCPP_ALWAYS_INLINE int __builtin_clzl(unsigned long mask)
+{
+  unsigned long where;
+  // Search from LSB to MSB for first set bit.
+  // Returns zero if no set bit is found.
+  if (_BitScanReverse(&where, mask))
+    return static_cast<int>(31 - where);
+  return 32; // Undefined Behavior.
+}
+
+_LIBCPP_ALWAYS_INLINE int __builtin_clz(unsigned int x)
+{
+  return __builtin_clzl(x);
+}
+
+#endif // _LIBCPP_SUPPORT_WIN32_MSVC_SUPPORT_H

include/support/win32/support.h

-// -*- C++ -*-
-//===----------------------- support/win32/support.h ----------------------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is dual licensed under the MIT and the University of Illinois Open
-// Source Licenses. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef _LIBCPP_SUPPORT_WIN32_SUPPORT_H
-#define _LIBCPP_SUPPORT_WIN32_SUPPORT_H
-
-// Functions and constants used in libc++ that
-// are missing from the Windows C library.
-
-#include <wchar.h> // mbstate_t
-#include <cstdarg> // va_ macros
-// "builtins" not implemented here for Clang or GCC as they provide
-// implementations. Assuming required for elsewhere else, certainly MSVC.
-#if defined(_LIBCPP_COMPILER_MSVC)
-#include <intrin.h>
-#endif
-#define swprintf _snwprintf
-#define vswprintf _vsnwprintf
-
-#ifndef NOMINMAX
-#define NOMINMAX
-#endif
-
-// The mingw headers already define these as static.
-#ifndef __MINGW32__
-extern "C" {
-
-int vasprintf(char **sptr, const char *__restrict fmt, va_list ap);
-int asprintf(char **sptr, const char *__restrict fmt, ...);
-size_t mbsnrtowcs(wchar_t *__restrict dst, const char **__restrict src,
-                  size_t nmc, size_t len, mbstate_t *__restrict ps);
-size_t wcsnrtombs(char *__restrict dst, const wchar_t **__restrict src,
-                  size_t nwc, size_t len, mbstate_t *__restrict ps);
-}
-#endif // __MINGW32__
-
-#if defined(_LIBCPP_COMPILER_MSVC)
-
-// Bit builtin's make these assumptions when calling _BitScanForward/Reverse
-// etc. These assumptions are expected to be true for Win32/Win64 which this
-// file supports.
-static_assert(sizeof(unsigned long long) == 8, "");
-static_assert(sizeof(unsigned long) == 4, "");
-static_assert(sizeof(unsigned int) == 4, "");
-
-_LIBCPP_ALWAYS_INLINE int __builtin_popcount(unsigned int x)
-{
-  // Binary: 0101...
-  static const unsigned int m1 = 0x55555555;
-  // Binary: 00110011..
-  static const unsigned int m2 = 0x33333333;
-  // Binary:  4 zeros,  4 ones ...
-  static const unsigned int m4 = 0x0f0f0f0f;
-  // The sum of 256 to the power of 0,1,2,3...
-  static const unsigned int h01 = 0x01010101;
-  // Put count of each 2 bits into those 2 bits.
-  x -= (x >> 1) & m1;
-  // Put count of each 4 bits into those 4 bits.
-  x = (x & m2) + ((x >> 2) & m2);
-  // Put count of each 8 bits into those 8 bits.
-  x = (x + (x >> 4)) & m4;
-  // Returns left 8 bits of x + (x<<8) + (x<<16) + (x<<24).
-  return (x * h01) >> 24;
-}
-
-_LIBCPP_ALWAYS_INLINE int __builtin_popcountl(unsigned long x)
-{
-  return __builtin_popcount(static_cast<int>(x));
-}
-
-_LIBCPP_ALWAYS_INLINE int __builtin_popcountll(unsigned long long x)
-{
-  // Binary: 0101...
-  static const unsigned long long m1 = 0x5555555555555555;
-  // Binary: 00110011..
-  static const unsigned long long m2 = 0x3333333333333333;
-  // Binary:  4 zeros,  4 ones ...
-  static const unsigned long long m4 = 0x0f0f0f0f0f0f0f0f;
-  // The sum of 256 to the power of 0,1,2,3...
-  static const unsigned long long h01 = 0x0101010101010101;
-  // Put count of each 2 bits into those 2 bits.
-  x -= (x >> 1) & m1;
-  // Put count of each 4 bits into those 4 bits.
-  x = (x & m2) + ((x >> 2) & m2);
-  // Put count of each 8 bits into those 8 bits.
-  x = (x + (x >> 4)) & m4;
-  // Returns left 8 bits of x + (x<<8) + (x<<16) + (x<<24) + ...
-  return static_cast<int>((x * h01) >> 56);
-}
-
-// Returns the number of trailing 0-bits in x, starting at the least significant
-// bit position. If x is 0, the result is undefined.
-_LIBCPP_ALWAYS_INLINE int __builtin_ctzll(unsigned long long mask)
-{
-  unsigned long where;
-// Search from LSB to MSB for first set bit.
-// Returns zero if no set bit is found.
-#if defined(_LIBCPP_HAS_BITSCAN64)
-    (defined(_M_AMD64) || defined(__x86_64__))
-  if (_BitScanForward64(&where, mask))
-    return static_cast<int>(where);
-#else
-  // Win32 doesn't have _BitScanForward64 so emulate it with two 32 bit calls.
-  // Scan the Low Word.
-  if (_BitScanForward(&where, static_cast<unsigned long>(mask)))
-    return static_cast<int>(where);
-  // Scan the High Word.
-  if (_BitScanForward(&where, static_cast<unsigned long>(mask >> 32)))
-    return static_cast<int>(where + 32); // Create a bit offset from the LSB.
-#endif
-  return 64;
-}
-
-_LIBCPP_ALWAYS_INLINE int __builtin_ctzl(unsigned long mask)
-{
-  unsigned long where;
-  // Search from LSB to MSB for first set bit.
-  // Returns zero if no set bit is found.
-  if (_BitScanForward(&where, mask))
-    return static_cast<int>(where);
-  return 32;
-}
-
-_LIBCPP_ALWAYS_INLINE int __builtin_ctz(unsigned int mask)
-{
-  // Win32 and Win64 expectations.
-  static_assert(sizeof(mask) == 4, "");
-  static_assert(sizeof(unsigned long) == 4, "");
-  return __builtin_ctzl(static_cast<unsigned long>(mask));
-}
-
-// Returns the number of leading 0-bits in x, starting at the most significant
-// bit position. If x is 0, the result is undefined.
-_LIBCPP_ALWAYS_INLINE int __builtin_clzll(unsigned long long mask)
-{
-  unsigned long where;
-// BitScanReverse scans from MSB to LSB for first set bit.
-// Returns 0 if no set bit is found.
-#if defined(_LIBCPP_HAS_BITSCAN64)
-  if (_BitScanReverse64(&where, mask))
-    return static_cast<int>(63 - where);
-#else
-  // Scan the high 32 bits.
-  if (_BitScanReverse(&where, static_cast<unsigned long>(mask >> 32)))
-    return static_cast<int>(63 -
-                            (where + 32)); // Create a bit offset from the MSB.
-  // Scan the low 32 bits.
-  if (_BitScanReverse(&where, static_cast<unsigned long>(mask)))
-    return static_cast<int>(63 - where);
-#endif
-  return 64; // Undefined Behavior.
-}
-
-_LIBCPP_ALWAYS_INLINE int __builtin_clzl(unsigned long mask)
-{
-  unsigned long where;
-  // Search from LSB to MSB for first set bit.
-  // Returns zero if no set bit is found.
-  if (_BitScanReverse(&where, mask))
-    return static_cast<int>(31 - where);
-  return 32; // Undefined Behavior.
-}
-
-_LIBCPP_ALWAYS_INLINE int __builtin_clz(unsigned int x)
-{
-  return __builtin_clzl(x);
-}
-#endif // _LIBCPP_MSVC
-
-#endif // _LIBCPP_SUPPORT_WIN32_SUPPORT_H

include/wchar.h

 wchar_t* __libcpp_wmemchr(const wchar_t* __s, wchar_t __c, size_t __n) {return (wchar_t*)wmemchr(__s, __c, __n);}
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_PREFERRED_OVERLOAD
 const wchar_t* wmemchr(const wchar_t* __s, wchar_t __c, size_t __n) {return __libcpp_wmemchr(__s, __c, __n);}
 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_PREFERRED_OVERLOAD
       wchar_t* wmemchr(      wchar_t* __s, wchar_t __c, size_t __n) {return __libcpp_wmemchr(__s, __c, __n);}
 }
 #endif
 
-#if defined(__cplusplus) && (defined(_LIBCPP_MSVCRT) || defined(__MINGW32__))
-extern "C++" {
-#include <support/win32/support.h> // pull in *swprintf defines
+#if defined(__cplusplus) && defined(_LIBCPP_MSVCRT)
+extern "C" {
+size_t mbsnrtowcs(wchar_t *__restrict dst, const char **__restrict src,
+                  size_t nmc, size_t len, mbstate_t *__restrict ps);
+size_t wcsnrtombs(char *__restrict dst, const wchar_t **__restrict src,
+                  size_t nwc, size_t len, mbstate_t *__restrict ps);
 }  // extern "C++"
 #endif  // __cplusplus && _LIBCPP_MSVCRT
 
 #endif  // _LIBCPP_WCHAR_H

src/string.cpp

 //===------------------------- string.cpp ---------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include "string"
 #include "cstdlib"
 #include "cwchar"
 #include "cerrno"
 #include "limits"
 #include "stdexcept"
-#ifdef _LIBCPP_MSVCRT
-#include "support/win32/support.h"
-#endif // _LIBCPP_MSVCRT
 #include <stdio.h>
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __basic_string_common<true>;
 
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_string<char>;
 template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_string<wchar_t>;

 
 inline
 wide_printf
 get_swprintf()
 {
 #ifndef _LIBCPP_MSVCRT
     return swprintf;
 #else
-    return static_cast<int (__cdecl*)(wchar_t* __restrict, size_t, const wchar_t*__restrict, ...)>(swprintf);
+    return static_cast<int (__cdecl*)(wchar_t* __restrict, size_t, const wchar_t*__restrict, ...)>(_snwprintf);
 #endif
 }
 
 }  // unnamed namespace
 
 string to_string(int val)
 {
     return as_string(snprintf, initial_string<string, int>()(), "%d", val);

src/support/runtime/exception_pointer_msvc.ipp

 // -*- C++ -*-
 //===----------------------------------------------------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is dual licensed under the MIT and the University of Illinois Open
 // Source Licenses. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <yvals.h> // for _CRTIMP2_PURE
 
 _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCreate(_Out_ void*);
 _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrDestroy(_Inout_ void*);
 _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL __ExceptionPtrCopy(_Out_ void*,
                                                               _In_ const void*);
 _CRTIMP2_PURE void __CLRCALL_PURE_OR_CDECL
 __ExceptionPtrAssign(_Inout_ void*, _In_ const void*);
 _CRTIMP2_PURE bool __CLRCALL_PURE_OR_CDECL