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[libc++] Remove workarounds for the lack of clock_gettime on older macOS platforms 

This increases the Mac OS requirement for building libc++ to 10.12.
Note that it doesn't change whether the *headers* still support older
platforms -- it's only that macOS >= 10.12 is required to build the
dylib from sources.

Differential Revision: https://reviews.llvm.org/D74489
This commit is contained in:
Louis Dionne 2020-02-12 17:01:19 +01:00
parent 81cca98768
commit babd3aefc9
4 changed files with 61 additions and 124 deletions
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47
libcxx/docs/index.rst
View File

@ -85,25 +85,46 @@ reasons, but some of the major ones are:
Platform and Compiler Support
-----------------------------
libc++ is known to work on the following platforms, using gcc and
clang.
Note that functionality provided by ``<atomic>`` is only functional with clang
and GCC.
For using the libc++ headers
############################
The libc++ headers are known to work on the following platforms, using GCC and
Clang. Note that functionality provided by ``<atomic>`` is only functional with
Clang and GCC.
============ ==================== ============ ========================
OS Arch Compilers ABI Library
============ ==================== ============ ========================
macOS i386, x86_64 Clang, GCC libc++abi
FreeBSD 10+ i386, x86_64, ARM Clang, GCC libcxxrt, libc++abi
Linux i386, x86_64 Clang, GCC libc++abi
============ ==================== ============ ========================
============ ==================== ============
OS Arch Compilers
============ ==================== ============
macOS 10.9+ i386, x86_64 Clang, GCC
FreeBSD 10+ i386, x86_64, ARM Clang, GCC
Linux i386, x86_64 Clang, GCC
============ ==================== ============
The following minimum compiler versions are strongly recommended.
The following minimum compiler versions are required:
* Clang 4.0 and above
* GCC 5.0 and above.
The C++03 dialect is only supported with Clang.
For building the libc++ library
###############################
Building the libc++ library (static or shared) requires some features from
the operating system. As such, it has its own set of (slightly different)
system requirements.
============ ==================== ============ ========================
OS Arch Compilers ABI Library
============ ==================== ============ ========================
macOS 10.12+ i386, x86_64 Clang, GCC libc++abi
FreeBSD 10+ i386, x86_64, ARM Clang, GCC libcxxrt, libc++abi
Linux i386, x86_64 Clang, GCC libc++abi
============ ==================== ============ ========================
The following minimum compiler versions are required:
* Clang 4.0 and above
* GCC 5.0 and above.
The C++03 dialect is only supported for Clang compilers.
C++ Dialect Support
---------------------

108
libcxx/src/chrono.cpp
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@ -9,7 +9,7 @@
#include "chrono"
#include "cerrno" // errno
#include "system_error" // __throw_system_error
#include <time.h> // clock_gettime, CLOCK_MONOTONIC and CLOCK_REALTIME
#include <time.h> // clock_gettime and CLOCK_{MONOTONIC,REALTIME,MONOTONIC_RAW}
#include "include/apple_availability.h"
#if __has_include(<unistd.h>)
@ -21,28 +21,20 @@
#endif
#if defined(_LIBCPP_WIN32API)
#define WIN32_LEAN_AND_MEAN
#define VC_EXTRA_LEAN
#include <windows.h>
#if _WIN32_WINNT >= _WIN32_WINNT_WIN8
#include <winapifamily.h>
#endif
# define WIN32_LEAN_AND_MEAN
# define VC_EXTRA_LEAN
# include <windows.h>
# if _WIN32_WINNT >= _WIN32_WINNT_WIN8
# include <winapifamily.h>
# endif
#else
#if !defined(CLOCK_REALTIME) || !defined(_LIBCPP_USE_CLOCK_GETTIME)
#include <sys/time.h> // for gettimeofday and timeval
#endif
# if !defined(CLOCK_REALTIME)
# include <sys/time.h> // for gettimeofday and timeval
# endif // !defined(CLOCK_REALTIME)
#endif // defined(_LIBCPP_WIN32API)
#if !defined(_LIBCPP_HAS_NO_MONOTONIC_CLOCK)
#if __APPLE__
#include <mach/mach_time.h> // mach_absolute_time, mach_timebase_info_data_t
#elif !defined(_LIBCPP_WIN32API) && !defined(CLOCK_MONOTONIC)
#error "Monotonic clock not implemented"
#endif
#endif
#if defined(__ELF__) && defined(_LIBCPP_LINK_RT_LIB)
#pragma comment(lib, "rt")
# pragma comment(lib, "rt")
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
@ -82,7 +74,7 @@ system_clock::now() _NOEXCEPT
static_cast<__int64>(ft.dwLowDateTime)};
return time_point(duration_cast<duration>(d - nt_to_unix_epoch));
#else
#if defined(_LIBCPP_USE_CLOCK_GETTIME) && defined(CLOCK_REALTIME)
#if defined(CLOCK_REALTIME)
struct timespec tp;
if (0 != clock_gettime(CLOCK_REALTIME, &tp))
__throw_system_error(errno, "clock_gettime(CLOCK_REALTIME) failed");
@ -91,7 +83,7 @@ system_clock::now() _NOEXCEPT
timeval tv;
gettimeofday(&tv, 0);
return time_point(seconds(tv.tv_sec) + microseconds(tv.tv_usec));
#endif // _LIBCPP_USE_CLOCK_GETTIME && CLOCK_REALTIME
#endif // CLOCK_REALTIME
#endif
}
@ -118,8 +110,15 @@ const bool steady_clock::is_steady;
#if defined(__APPLE__)
// Darwin libc versions >= 1133 provide ns precision via CLOCK_MONOTONIC_RAW
#if defined(_LIBCPP_USE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC_RAW)
#if !defined(CLOCK_MONOTONIC_RAW)
# error "Building libc++ on Apple platforms requires CLOCK_MONOTONIC_RAW"
#endif
// On Apple platforms, only CLOCK_UPTIME_RAW, CLOCK_MONOTONIC_RAW or
// mach_absolute_time are able to time functions in the nanosecond range.
// Furthermore, only CLOCK_MONOTONIC_RAW is truly monotonic, because it
// also counts cycles when the system is asleep. Thus, it is the only
// acceptable implementation of steady_clock.
steady_clock::time_point
steady_clock::now() _NOEXCEPT
{
@ -129,60 +128,6 @@ steady_clock::now() _NOEXCEPT
return time_point(seconds(tp.tv_sec) + nanoseconds(tp.tv_nsec));
}
#else
// mach_absolute_time() * MachInfo.numer / MachInfo.denom is the number of
// nanoseconds since the computer booted up. MachInfo.numer and MachInfo.denom
// are run time constants supplied by the OS. This clock has no relationship
// to the Gregorian calendar. It's main use is as a high resolution timer.
// MachInfo.numer / MachInfo.denom is often 1 on the latest equipment. Specialize
// for that case as an optimization.
static
steady_clock::rep
steady_simplified()
{
return static_cast<steady_clock::rep>(mach_absolute_time());
}
static
double
compute_steady_factor()
{
mach_timebase_info_data_t MachInfo;
mach_timebase_info(&MachInfo);
return static_cast<double>(MachInfo.numer) / MachInfo.denom;
}
static
steady_clock::rep
steady_full()
{
static const double factor = compute_steady_factor();
return static_cast<steady_clock::rep>(mach_absolute_time() * factor);
}
typedef steady_clock::rep (*FP)();
static
FP
init_steady_clock()
{
mach_timebase_info_data_t MachInfo;
mach_timebase_info(&MachInfo);
if (MachInfo.numer == MachInfo.denom)
return &steady_simplified;
return &steady_full;
}
steady_clock::time_point
steady_clock::now() _NOEXCEPT
{
static FP fp = init_steady_clock();
return time_point(duration(fp()));
}
#endif // defined(_LIBCPP_USE_CLOCK_GETTIME) && defined(CLOCK_MONOTONIC_RAW)
#elif defined(_LIBCPP_WIN32API)
// https://msdn.microsoft.com/en-us/library/windows/desktop/ms644905(v=vs.85).aspx says:
@ -210,13 +155,6 @@ steady_clock::now() _NOEXCEPT
#elif defined(CLOCK_MONOTONIC)
// On Apple platforms only CLOCK_UPTIME_RAW, CLOCK_MONOTONIC_RAW or
// mach_absolute_time are able to time functions in the nanosecond range.
// Thus, they are the only acceptable implementations of steady_clock.
#ifdef __APPLE__
#error "Never use CLOCK_MONOTONIC for steady_clock::now on Apple platforms"
#endif
steady_clock::time_point
steady_clock::now() _NOEXCEPT
{
@ -227,7 +165,7 @@ steady_clock::now() _NOEXCEPT
}
#else
#error "Monotonic clock not implemented"
# error "Monotonic clock not implemented"
#endif
#endif // !_LIBCPP_HAS_NO_MONOTONIC_CLOCK

12
libcxx/src/filesystem/operations.cpp
View File

@ -36,13 +36,9 @@
#define _LIBCPP_USE_COPYFILE
#endif
#if !defined(__APPLE__) && _POSIX_TIMERS > 0
#define _LIBCPP_USE_CLOCK_GETTIME
#endif
#if !defined(CLOCK_REALTIME) || !defined(_LIBCPP_USE_CLOCK_GETTIME)
#if !defined(CLOCK_REALTIME)
#include <sys/time.h> // for gettimeofday and timeval
#endif // !defined(CLOCK_REALTIME)
#endif // !defined(CLOCK_REALTIME)
#if defined(__ELF__) && defined(_LIBCPP_LINK_RT_LIB)
#pragma comment(lib, "rt")
@ -490,7 +486,7 @@ const bool _FilesystemClock::is_steady;
_FilesystemClock::time_point _FilesystemClock::now() noexcept {
typedef chrono::duration<rep> __secs;
#if defined(_LIBCPP_USE_CLOCK_GETTIME) && defined(CLOCK_REALTIME)
#if defined(CLOCK_REALTIME)
typedef chrono::duration<rep, nano> __nsecs;
struct timespec tp;
if (0 != clock_gettime(CLOCK_REALTIME, &tp))
@ -502,7 +498,7 @@ _FilesystemClock::time_point _FilesystemClock::now() noexcept {
timeval tv;
gettimeofday(&tv, 0);
return time_point(__secs(tv.tv_sec) + __microsecs(tv.tv_usec));
#endif // _LIBCPP_USE_CLOCK_GETTIME && CLOCK_REALTIME
#endif // CLOCK_REALTIME
}
filesystem_error::~filesystem_error() {}

18
libcxx/src/include/apple_availability.h
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@ -28,24 +28,6 @@
#endif
#endif // __ENVIRONMENT_.*_VERSION_MIN_REQUIRED__
#if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__)
#if __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 101200
#define _LIBCPP_USE_CLOCK_GETTIME
#endif
#elif defined(__ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__)
#if __ENVIRONMENT_IPHONE_OS_VERSION_MIN_REQUIRED__ >= 100000
#define _LIBCPP_USE_CLOCK_GETTIME
#endif
#elif defined(__ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__)
#if __ENVIRONMENT_TV_OS_VERSION_MIN_REQUIRED__ >= 100000
#define _LIBCPP_USE_CLOCK_GETTIME
#endif
#elif defined(__ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__)
#if __ENVIRONMENT_WATCH_OS_VERSION_MIN_REQUIRED__ >= 30000
#define _LIBCPP_USE_CLOCK_GETTIME
#endif
#endif // __ENVIRONMENT_.*_VERSION_MIN_REQUIRED__
#if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__)
#if __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 101500
#define _LIBCPP_USE_ULOCK