Add some comments explaining what MVT and EVT are, and how they differ.

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

diff --git a/include/llvm/System/RWMutex.h b/include/llvm/System/RWMutex.h
index 6a254b873a5340bedc95e21770ef2f88bc4ff855..3a288180bf0756837bc73875eb5c7df3ad995bb0 100644 (file)
--- a/include/llvm/System/RWMutex.h
+++ b/include/llvm/System/RWMutex.h
@@ -15,6 +15,7 @@
 #define LLVM_SYSTEM_RWMUTEX_H
 
 #include "llvm/System/Threading.h"
+#include <cassert>
 
 namespace llvm
 {
@@ -68,9 +69,7 @@ namespace llvm
     /// @name Platform Dependent Data
     /// @{
     private:
-#ifdef ENABLE_THREADS
       void* data_; ///< We don't know what the data will be
-#endif
 
     /// @}
     /// @name Do Not Implement
@@ -85,31 +84,51 @@ namespace llvm
     /// indicates whether this mutex should become a no-op when we're not
     /// running in multithreaded mode.
     template<bool mt_only>
-    class SmartRWMutex : RWMutexImpl {
+    class SmartRWMutex : public RWMutexImpl {
+      unsigned readers, writers;
     public:
-      explicit SmartRWMutex() : RWMutexImpl() { }
+      explicit SmartRWMutex() : RWMutexImpl(), readers(0), writers(0) { }
       
       bool reader_acquire() {
-        if (!mt_only && llvm_is_multithreaded())
+        if (!mt_only || llvm_is_multithreaded())
           return RWMutexImpl::reader_acquire();
+        
+        // Single-threaded debugging code.  This would be racy in multithreaded
+        // mode, but provides not sanity checks in single threaded mode.
+        ++readers;
         return true;
       }
       
       bool reader_release() {
         if (!mt_only || llvm_is_multithreaded())
           return RWMutexImpl::reader_release();
+        
+        // Single-threaded debugging code.  This would be racy in multithreaded
+        // mode, but provides not sanity checks in single threaded mode.
+        assert(readers > 0 && "Reader lock not acquired before release!");
+        --readers;
         return true;
       }
       
       bool writer_acquire() {
         if (!mt_only || llvm_is_multithreaded())
           return RWMutexImpl::writer_acquire();
+        
+        // Single-threaded debugging code.  This would be racy in multithreaded
+        // mode, but provides not sanity checks in single threaded mode.
+        assert(writers == 0 && "Writer lock already acquired!");
+        ++writers;
         return true;
       }
       
       bool writer_release() {
         if (!mt_only || llvm_is_multithreaded())
           return RWMutexImpl::writer_release();
+        
+        // Single-threaded debugging code.  This would be racy in multithreaded
+        // mode, but provides not sanity checks in single threaded mode.
+        assert(writers == 1 && "Writer lock not acquired before release!");
+        --writers;
         return true;
       }
       
@@ -122,15 +141,14 @@ namespace llvm
     /// ScopedReader - RAII acquisition of a reader lock
     template<bool mt_only>
     struct SmartScopedReader {
-      SmartRWMutex<mt_only>* mutex;
+      SmartRWMutex<mt_only>& mutex;
       
-      explicit SmartScopedReader(SmartRWMutex<mt_only>* m) {
-        mutex = m;
-        mutex->reader_acquire();
+      explicit SmartScopedReader(SmartRWMutex<mt_only>& m) : mutex(m) {
+        mutex.reader_acquire();
       }
       
       ~SmartScopedReader() {
-        mutex->reader_release();
+        mutex.reader_release();
       }
     };
     typedef SmartScopedReader<false> ScopedReader;
@@ -138,15 +156,14 @@ namespace llvm
     /// ScopedWriter - RAII acquisition of a writer lock
     template<bool mt_only>
     struct SmartScopedWriter {
-      SmartRWMutex<mt_only>* mutex;
+      SmartRWMutex<mt_only>& mutex;
       
-      explicit SmartScopedWriter(SmartRWMutex<mt_only>* m) {
-        mutex = m;
-        mutex->writer_acquire();
+      explicit SmartScopedWriter(SmartRWMutex<mt_only>& m) : mutex(m) {
+        mutex.writer_acquire();
       }
       
       ~SmartScopedWriter() {
-        mutex->writer_release();
+        mutex.writer_release();
       }
     };
     typedef SmartScopedWriter<false> ScopedWriter;