Changeset 27336 in webkit for trunk/JavaScriptCore/wtf/TCSpinLock.h

Timestamp:

Oct 31, 2007, 6:22:35 PM (18 years ago)

Author:

aroben

Message:

Fix a crash on launch due to a static initializer race

We now use fast inline assembler spinlocks which can be statically
initialized at compile time.

As a side benefit, this speeds up SunSpider by 0.4%.

Reviewed by Oliver.

• wtf/FastMalloc.cpp:
• wtf/TCSpinLock.h: (TCMalloc_SpinLock::Lock): (TCMalloc_SpinLock::Unlock): (TCMalloc_SlowLock):
• wtf/TCSystemAlloc.cpp:

File:

• trunk/JavaScriptCore/wtf/TCSpinLock.h (modified) (8 diffs)

trunk/JavaScriptCore/wtf/TCSpinLock.h

@@ -34 +34 @@
 #define TCMALLOC_INTERNAL_SPINLOCK_H__
 
-#if (PLATFORM(X86) || PLATFORM(PPC)) && COMPILER(GCC)
+#if (PLATFORM(X86) || PLATFORM(PPC)) && (COMPILER(GCC) || COMPILER(MSVC))
 
 #include <time.h>       /* For nanosleep() */
@@ -48 +48 @@
 #endif
 #include <stdlib.h>     /* for abort() */
+
+#if COMPILER(MSVC)
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#endif
 
 static void TCMalloc_SlowLock(volatile unsigned int* lockword);
@@ -60 +65 @@
   inline void Lock() {
     int r;
+#if COMPILER(GCC)
 #if PLATFORM(X86)
     __asm__ __volatile__
@@ -77 +83 @@
          : "memory");
 #endif
+#elif COMPILER(MSVC)
+    __asm {
+        mov eax, this    ; store &private_lockword_ (which is this+0) in eax
+        mov ebx, 1       ; store 1 in ebx
+        xchg [eax], ebx  ; exchange private_lockword_ and 1
+        mov r, ebx       ; store old value of private_lockword_ in r
+    }
+#endif
     if (r) TCMalloc_SlowLock(&private_lockword_);
   }
 
   inline void Unlock() {
+#if COMPILER(GCC)
 #if PLATFORM(X86)
     __asm__ __volatile__
@@ -96 +111 @@
        : "memory");
 #endif
+#elif COMPILER(MSVC)
+      __asm {
+          mov eax, this  ; store &private_lockword_ (which is this+0) in eax
+          mov [eax], 0   ; set private_lockword_ to 0
+      }
+#endif
   }
 
@@ -111 +132 @@
   while (true) {
     int r;
+#if COMPILER(GCC)
 #if PLATFORM(X86)
     __asm__ __volatile__
@@ -128 +150 @@
          : "r" (tmp), "1" (lockword)
          : "memory");
+#endif
+#elif COMPILER(MSVC)
+    __asm {
+        mov eax, lockword     ; assign lockword into eax
+        mov ebx, 1            ; assign 1 into ebx
+        xchg [eax], ebx       ; exchange *lockword and 1
+        mov r, ebx            ; store old value of *lockword in r
+    }
 #endif
     if (!r) {
@@ -143 +173 @@
 
     // Sleep for a few milliseconds
+#if COMPILER(MSVC)
+    Sleep(2);
+#else
     struct timespec tm;
     tm.tv_sec = 0;
     tm.tv_nsec = 2000001;
     nanosleep(&tm, NULL);
+#endif
   }
 }
-
-#elif COMPILER(MSVC)
-
-#define WIN32_LEAN_AND_MEAN
-#include <windows.h>
-
-struct TCMalloc_SpinLock {
-  CRITICAL_SECTION private_lock_;
-
-  inline TCMalloc_SpinLock() {
-    Init();
-  }
-
-  inline void Init() {
-    InitializeCriticalSection(&private_lock_);
-  }
-  inline void Finalize() {
-    DeleteCriticalSection(&private_lock_);
-  }
-  inline void Lock() {
-    EnterCriticalSection(&private_lock_);
-  }
-  inline void Unlock() {
-    LeaveCriticalSection(&private_lock_);
-  }
-};
 
 #else