Use instruction itinerary to determine what instructions are 'cheap'.

[oota-llvm.git] / include / llvm / System / Mutex.h

diff --git a/include/llvm/System/Mutex.h b/include/llvm/System/Mutex.h
index 5254703cbf1502f4965c4646b8af0f7e126a853b..71d10067c303442ffda43d857709106c9fb88f77 100644 (file)
--- a/include/llvm/System/Mutex.h
+++ b/include/llvm/System/Mutex.h
@@ -2,8 +2,8 @@
 //
 //                     The LLVM Compiler Infrastructure
 //
-// This file was developed by Reid Spencer and is distributed under the
-// University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
@@ -14,12 +14,15 @@
 #ifndef LLVM_SYSTEM_MUTEX_H
 #define LLVM_SYSTEM_MUTEX_H
 
+#include "llvm/System/Threading.h"
+#include <cassert>
+
 namespace llvm
 {
   namespace sys
   {
     /// @brief Platform agnostic Mutex class.
-    class Mutex
+    class MutexImpl
     {
     /// @name Constructors
     /// @{
@@ -30,11 +33,11 @@ namespace llvm
       /// also more likely to deadlock (same thread can't acquire more than
       /// once).
       /// @brief Default Constructor.
-      Mutex ( bool recursive = true );
+      explicit MutexImpl(bool recursive = true);
 
       /// Releases and removes the lock
       /// @brief Destructor
-      ~Mutex ( void );
+      ~MutexImpl();
 
     /// @}
     /// @name Methods
@@ -52,7 +55,7 @@ namespace llvm
       /// lock.
       /// @returns false if any kind of error occurs, true otherwise.
       /// @brief Unconditionally release the lock.
-      bool release(void);
+      bool release();
 
       /// Attempts to acquire the lock without blocking. If the lock is not
       /// available, this function returns false quickly (without blocking). If
@@ -72,10 +75,79 @@ namespace llvm
     /// @name Do Not Implement
     /// @{
     private:
-      Mutex(const Mutex & original);
-      void operator=(const Mutex &);
+      MutexImpl(const MutexImpl & original);
+      void operator=(const MutexImpl &);
     /// @}
     };
+    
+    
+    /// SmartMutex - A mutex with a compile time constant parameter that 
+    /// indicates whether this mutex should become a no-op when we're not
+    /// running in multithreaded mode.
+    template<bool mt_only>
+    class SmartMutex : public MutexImpl {
+      unsigned acquired;
+      bool recursive;
+    public:
+      explicit SmartMutex(bool rec = true) :
+        MutexImpl(rec), acquired(0), recursive(rec) { }
+      
+      bool acquire() {
+        if (!mt_only || llvm_is_multithreaded()) {
+          return MutexImpl::acquire();
+        } else {
+          // Single-threaded debugging code.  This would be racy in
+          // multithreaded mode, but provides not sanity checks in single
+          // threaded mode.
+          assert((recursive || acquired == 0) && "Lock already acquired!!");
+          ++acquired;
+          return true;
+        }
+      }
+
+      bool release() {
+        if (!mt_only || llvm_is_multithreaded()) {
+          return MutexImpl::release();
+        } else {
+          // Single-threaded debugging code.  This would be racy in
+          // multithreaded mode, but provides not sanity checks in single
+          // threaded mode.
+          assert(((recursive && acquired) || (acquired == 1)) &&
+                 "Lock not acquired before release!");
+          --acquired;
+          return true;
+        }
+      }
+
+      bool tryacquire() {
+        if (!mt_only || llvm_is_multithreaded())
+          return MutexImpl::tryacquire();
+        else return true;
+      }
+      
+      private:
+        SmartMutex(const SmartMutex<mt_only> & original);
+        void operator=(const SmartMutex<mt_only> &);
+    };
+    
+    /// Mutex - A standard, always enforced mutex.
+    typedef SmartMutex<false> Mutex;
+    
+    template<bool mt_only>
+    class SmartScopedLock  {
+      SmartMutex<mt_only>& mtx;
+      
+    public:
+      SmartScopedLock(SmartMutex<mt_only>& m) : mtx(m) {
+        mtx.acquire();
+      }
+      
+      ~SmartScopedLock() {
+        mtx.release();
+      }
+    };
+    
+    typedef SmartScopedLock<false> ScopedLock;
   }
 }