Add model numbers for Skylake CPUs and an additional Broadwell model.

[oota-llvm.git] / lib / Support / Windows / RWMutex.inc

diff --git a/lib/Support/Windows/RWMutex.inc b/lib/Support/Windows/RWMutex.inc
index 82ae8af1e52676b4cc86bb0d7a7341c749adf8dc..2d1d25f67b8aa646a009a1efa7588b46128e36a2 100644 (file)
--- a/lib/Support/Windows/RWMutex.inc
+++ b/lib/Support/Windows/RWMutex.inc
@@ -1,4 +1,4 @@
-//= llvm/System/Win32/Mutex.inc - Win32 Reader/Writer Mutual Exclusion Lock  =//
+//= llvm/Support/Win32/Mutex.inc - Win32 Reader/Writer Mutual Exclusion Lock  =//
 //
 //                     The LLVM Compiler Infrastructure
 //
@@ -16,41 +16,113 @@
 //===          is guaranteed to work on *all* Win32 variants.
 //===----------------------------------------------------------------------===//
 
-#include "Windows.h"
-
-// FIXME: Windows does not have reader-writer locks pre-Vista.  If you want
-// real reader-writer locks, you a threads implementation for Windows.
+#include "WindowsSupport.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() {
-  data_ = calloc(1, sizeof(CRITICAL_SECTION));
-  InitializeCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  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() {
-  DeleteCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  if (!sHasSRW)
+    DeleteCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  // Nothing to do in the case of slim reader/writers except free the memory.
   free(data_);
 }
 
 bool RWMutexImpl::reader_acquire() {
-  EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  if (sHasSRW) {
+    fpAcquireSRWLockShared(static_cast<PSRWLOCK>(data_));
+  } else {
+    EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  }
   return true;
 }
 
 bool RWMutexImpl::reader_release() {
-  LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  if (sHasSRW) {
+    fpReleaseSRWLockShared(static_cast<PSRWLOCK>(data_));
+  } else {
+    LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  }
   return true;
 }
 
 bool RWMutexImpl::writer_acquire() {
-  EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  if (sHasSRW) {
+    fpAcquireSRWLockExclusive(static_cast<PSRWLOCK>(data_));
+  } else {
+    EnterCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  }
   return true;
 }
 
 bool RWMutexImpl::writer_release() {
-  LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  if (sHasSRW) {
+    fpReleaseSRWLockExclusive(static_cast<PSRWLOCK>(data_));
+  } else {
+    LeaveCriticalSection(static_cast<LPCRITICAL_SECTION>(data_));
+  }
   return true;
 }