1 files changed, 132 insertions, 0 deletions
diff --git a/contrib/llvm/lib/Support/Windows/RWMutex.inc b/contrib/llvm/lib/Support/Windows/RWMutex.inc
new file mode 100644
index 000000000000..c4318448e7ce
--- /dev/null
+++ b/contrib/llvm/lib/Support/Windows/RWMutex.inc
@@ -0,0 +1,132 @@
+//= llvm/Support/Win32/Mutex.inc - Win32 Reader/Writer Mutual Exclusion Lock  =//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the Win32 specific (non-pthread) RWMutex class.
+//
+//===----------------------------------------------------------------------===//
+
+//===----------------------------------------------------------------------===//
+//=== WARNING: Implementation here must contain only generic Win32 code that
+//===          is guaranteed to work on *all* Win32 variants.
+//===----------------------------------------------------------------------===//
+
+#include "Windows.h"
+
+namespace llvm {
+using namespace sys;
+
+// Windows has slim read-writer lock support on Vista and higher, so we
+// will attempt to load the APIs.  If they exist, we will use them, and
+// if not, we will fall back on critical sections.  When we drop support
+// for XP, we can stop lazy-loading these APIs and just use them directly.
+#if defined(__MINGW32__)
+  // Taken from WinNT.h
+  typedef struct _RTL_SRWLOCK {
+    PVOID Ptr;
+  } RTL_SRWLOCK, *PRTL_SRWLOCK;
+
+  // Taken from WinBase.h
+  typedef RTL_SRWLOCK SRWLOCK, *PSRWLOCK;
+#endif
+
+static VOID (WINAPI *fpInitializeSRWLock)(PSRWLOCK lock) = NULL;
+static VOID (WINAPI *fpAcquireSRWLockExclusive)(PSRWLOCK lock) = NULL;
+static VOID (WINAPI *fpAcquireSRWLockShared)(PSRWLOCK lock) = NULL;
+static VOID (WINAPI *fpReleaseSRWLockExclusive)(PSRWLOCK lock) = NULL;
+static VOID (WINAPI *fpReleaseSRWLockShared)(PSRWLOCK lock) = NULL;
+
+static bool sHasSRW = false;
+
+static bool loadSRW() {
+  static bool sChecked = false;
+  if (!sChecked) {
+    sChecked = true;
+
+    if (HMODULE hLib = ::GetModuleHandleW(L"Kernel32.dll")) {
+      fpInitializeSRWLock =
+        (VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
+                                               "InitializeSRWLock");
+      fpAcquireSRWLockExclusive =
+        (VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
+                                               "AcquireSRWLockExclusive");
+      fpAcquireSRWLockShared =
+        (VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
+                                               "AcquireSRWLockShared");
+      fpReleaseSRWLockExclusive =
+        (VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
+                                               "ReleaseSRWLockExclusive");
+      fpReleaseSRWLockShared =
+        (VOID (WINAPI *)(PSRWLOCK))::GetProcAddress(hLib,
+                                               "ReleaseSRWLockShared");
+
+      if (fpInitializeSRWLock != NULL) {
+        sHasSRW = true;
+      }
+    }
+  }
+  return sHasSRW;
+}
+
+RWMutexImpl::RWMutexImpl() {
+  if (loadSRW()) {
+    data_ = calloc(1, sizeof(SRWLOCK));
+    fpInitializeSRWLock(static_cast<PSRWLOCK>(data_));
+  } else {
+    data_ = calloc(1, sizeof(CRITICAL_SECTION));
+    InitializeCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  }
+}
+
+RWMutexImpl::~RWMutexImpl() {
+  if (sHasSRW) {
+    // Nothing to do in the case of slim reader/writers
+  } else {
+    DeleteCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+    free(data_);
+  }
+}
+
+bool RWMutexImpl::reader_acquire() {
+  if (sHasSRW) {
+    fpAcquireSRWLockShared(static_cast<PSRWLOCK>(data_));
+  } else {
+    EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  }
+  return true;
+}
+
+bool RWMutexImpl::reader_release() {
+  if (sHasSRW) {
+    fpReleaseSRWLockShared(static_cast<PSRWLOCK>(data_));
+  } else {
+    LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  }
+  return true;
+}
+
+bool RWMutexImpl::writer_acquire() {
+  if (sHasSRW) {
+    fpAcquireSRWLockExclusive(static_cast<PSRWLOCK>(data_));
+  } else {
+    EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  }
+  return true;
+}
+
+bool RWMutexImpl::writer_release() {
+  if (sHasSRW) {
+    fpReleaseSRWLockExclusive(static_cast<PSRWLOCK>(data_));
+  } else {
+    LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  }
+  return true;
+}
+
+
+}