libstdc++: Refactor __semaphore_base member functions

Replace the _S_get_current and _S_do_try_acquire static member functions
with non-static member functions _M_get_current and _M_do_try_acquire.
This means they don't need the address of _M_counter passed in.

libstdc++-v3/ChangeLog:

	* include/bits/semaphore_base.h (_S_get_current): Replace with
	non-static _M_get_current.
	(_S_do_try_acquire): Replace with non-static _M_do_try_acquire.

Reviewed-by: Tomasz Kamiński <tkaminsk@redhat.com>

diff --git a/libstdc++-v3/include/bits/semaphore_base.h b/libstdc++-v3/include/bits/semaphore_base.h
index 526da4d82b6a62d6ee35c811e88e225288414da1..3f7a33ccd51a59b9ed0275f2b2121ede4f8efaca 100644 (file)
--- a/libstdc++-v3/include/bits/semaphore_base.h
+++ b/libstdc++-v3/include/bits/semaphore_base.h
@@ -64,20 +64,23 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     __semaphore_base(const __semaphore_base&) = delete;
     __semaphore_base& operator=(const __semaphore_base&) = delete;
 
-    static _GLIBCXX_ALWAYS_INLINE __count_type
-    _S_get_current(__count_type* __counter) noexcept
+    // Load the current counter value.
+    _GLIBCXX_ALWAYS_INLINE __count_type
+    _M_get_current() const noexcept
+    { return __atomic_impl::load(&_M_counter, memory_order::acquire); }
+
+    // Try to acquire the semaphore (i.e. decrement the counter).
+    // Returns false if the current counter is zero, or if another thread
+    // decrements the value first. In the latter case, __cur is set to the
+    // new value.
+    _GLIBCXX_ALWAYS_INLINE bool
+    _M_do_try_acquire(__count_type& __cur) noexcept
     {
-      return __atomic_impl::load(__counter, memory_order::acquire);
-    }
-
-    static _GLIBCXX_ALWAYS_INLINE bool
-    _S_do_try_acquire(__count_type* __counter, __count_type& __old) noexcept
-    {
-      if (__old == 0)
-       return false;
+      if (__cur == 0)
+       return false; // Cannot decrement when it's already zero.
 
-      return __atomic_impl::compare_exchange_strong(__counter,
-                                                   __old, __old - 1,
+      return __atomic_impl::compare_exchange_strong(&_M_counter,
+                                                   __cur, __cur - 1,
                                                    memory_order::acquire,
                                                    memory_order::relaxed);
     }
@@ -85,7 +88,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     void
     _M_acquire() noexcept
     {
-      auto const __vfn = [this]{ return _S_get_current(&this->_M_counter); };
+      auto const __vfn = [this]{ return _M_get_current(); };
       auto __val = __vfn();
       auto const __pred = [&__val](__count_type __cur) {
        if (__cur > 0)
@@ -95,7 +98,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
          }
        return false;
       };
-      while (!_S_do_try_acquire(&_M_counter, __val))
+      while (!_M_do_try_acquire(__val))
        if (__val == 0)
          std::__atomic_wait_address(&_M_counter, __pred, __vfn, true);
     }
@@ -103,7 +106,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     bool
     _M_try_acquire() noexcept
     {
-      // The fastest implementation of this function is just _S_do_try_acquire
+      // The fastest implementation of this function is just _M_do_try_acquire
       // but that can fail under contention even when _M_count > 0.
       // Using _M_try_acquire_for(0ns) will retry a few times in a loop.
       return _M_try_acquire_for(__detail::__wait_clock_t::duration{});
@@ -113,7 +116,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       bool
       _M_try_acquire_until(const chrono::time_point<_Clock, _Duration>& __atime) noexcept
       {
-       auto const __vfn = [this]{ return _S_get_current(&this->_M_counter); };
+       auto const __vfn = [this]{ return _M_get_current(); };
        auto __val = __vfn();
        auto const __pred = [&__val](__count_type __cur) {
          if (__cur > 0)
@@ -123,7 +126,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
            }
          return false;
        };
-       while (!_S_do_try_acquire(&this->_M_counter, __val))
+       while (!_M_do_try_acquire(__val))
          if (__val == 0)
            {
              if (!std::__atomic_wait_address_until(&_M_counter, __pred,
@@ -137,7 +140,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       bool
       _M_try_acquire_for(const chrono::duration<_Rep, _Period>& __rtime) noexcept
       {
-       auto const __vfn = [this]{ return _S_get_current(&this->_M_counter); };
+       auto const __vfn = [this]{ return _M_get_current(); };
        auto __val = __vfn();
        auto const __pred = [&__val](__count_type __cur) {
          if (__cur > 0)
@@ -147,7 +150,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
            }
          return false;
        };
-       while (!_S_do_try_acquire(&this->_M_counter, __val))
+       while (!_M_do_try_acquire(__val))
          if (__val == 0)
            {
              if (!std::__atomic_wait_address_for(&_M_counter, __pred,