Memory barriers for PPC

[Andrew Haley]

Zero is missing memory barriers for SMP systems.  Implemented
thusly; it was necessary to add PPC-specific code.  There are
probably some other systems out there that need similar treatment.

Andrew.


2009-01-27  Andrew Haley  <aph at redhat.com>

        * ports/hotspot/src/os_cpu/linux_zero/vm/orderAccess_linux_zero.inline.hpp:
        Add memory barriers where needed for PPC.

diff -r 86cc7eb0035f ports/hotspot/src/os_cpu/linux_zero/vm/orderAccess_linux_zero.inline.hpp
--- a/ports/hotspot/src/os_cpu/linux_zero/vm/orderAccess_linux_zero.inline.hpp	Mon Jan 26 09:09:26 2009 -0500
+++ b/ports/hotspot/src/os_cpu/linux_zero/vm/orderAccess_linux_zero.inline.hpp	Tue Jan 27 10:29:48 2009 +0000
@@ -23,6 +23,24 @@
  *
  */

+#ifdef __PPC
+
+#define READ_MEM_BARRIER __asm __volatile ("isync":::"memory")
+#ifdef __NO_LWSYNC__
+#define WRITE_MEM_BARRIER __asm __volatile ("sync":::"memory")
+#else
+#define WRITE_MEM_BARRIER __asm __volatile ("lwsync":::"memory")
+#endif
+
+#else // PPC
+
+#define READ_MEM_BARRIER __asm __volatile ("":::"memory")
+#define WRITE_MEM_BARRIER __asm __volatile ("":::"memory")
+
+#endif // PPC
+
+
+
 inline void OrderAccess::loadload()   { acquire(); }
 inline void OrderAccess::storestore() { release(); }
 inline void OrderAccess::loadstore()  { acquire(); }
@@ -30,12 +48,12 @@

 inline void OrderAccess::acquire()
 {
-  __sync_synchronize();
+  READ_MEM_BARRIER;
 }

 inline void OrderAccess::release()
 {
-  __sync_synchronize();
+  WRITE_MEM_BARRIER;
 }

 inline void OrderAccess::fence()
@@ -43,49 +61,71 @@
   __sync_synchronize();
 }

-inline jbyte    OrderAccess::load_acquire(volatile jbyte*   p) { return *p; }
-inline jshort   OrderAccess::load_acquire(volatile jshort*  p) { return *p; }
-inline jint     OrderAccess::load_acquire(volatile jint*    p) { return *p; }
+inline jbyte    OrderAccess::load_acquire(volatile jbyte*   p) { jbyte data = *p; acquire(); return data; }
+inline jshort   OrderAccess::load_acquire(volatile jshort*  p) { jshort data = *p; acquire(); return data; }
+inline jint     OrderAccess::load_acquire(volatile jint*    p) { jint data = *p; acquire(); return data; }
 inline jlong    OrderAccess::load_acquire(volatile jlong*   p)
 {
   jlong tmp;
   os::atomic_copy64(p, &tmp);
+  acquire();
   return tmp;
 }
-inline jubyte   OrderAccess::load_acquire(volatile jubyte*  p) { return *p; }
-inline jushort  OrderAccess::load_acquire(volatile jushort* p) { return *p; }
-inline juint    OrderAccess::load_acquire(volatile juint*   p) { return *p; }
+inline jubyte    OrderAccess::load_acquire(volatile jubyte*   p) { jubyte data = *p; acquire(); return data; }
+inline jushort   OrderAccess::load_acquire(volatile jushort*  p) { jushort data = *p; acquire(); return data; }
+inline juint     OrderAccess::load_acquire(volatile juint*    p) { juint data = *p; acquire(); return data; }
 inline julong   OrderAccess::load_acquire(volatile julong*  p)
 {
   julong tmp;
   os::atomic_copy64(p, &tmp);
+  acquire();
   return tmp;
 }
-inline jfloat   OrderAccess::load_acquire(volatile jfloat*  p) { return *p; }
+inline jfloat   OrderAccess::load_acquire(volatile jfloat*  p) { jfloat data = *p; acquire(); return data; }
 inline jdouble  OrderAccess::load_acquire(volatile jdouble* p)
 {
   jdouble tmp;
   os::atomic_copy64(p, &tmp);
+  acquire();
   return tmp;
 }

-inline intptr_t OrderAccess::load_ptr_acquire(volatile intptr_t*   p) { return *p; }
-inline void*    OrderAccess::load_ptr_acquire(volatile void*       p) { return *(void* volatile *)p; }
-inline void*    OrderAccess::load_ptr_acquire(const volatile void* p) { return *(void* const volatile *)p; }
+inline intptr_t OrderAccess::load_ptr_acquire(volatile intptr_t*   p)
+{
+  intptr_t data = *p;
+  acquire();
+  return data;
+}
+inline void*    OrderAccess::load_ptr_acquire(volatile void*       p)
+{
+  void *data = *(void* volatile *)p;
+  acquire();
+  return data;
+}
+inline void*    OrderAccess::load_ptr_acquire(const volatile void* p)
+{
+  void *data = *(void* const volatile *)p;
+  acquire();
+  return data;
+}

-inline void     OrderAccess::release_store(volatile jbyte*   p, jbyte   v) { *p = v; }
-inline void     OrderAccess::release_store(volatile jshort*  p, jshort  v) { *p = v; }
-inline void     OrderAccess::release_store(volatile jint*    p, jint    v) { *p = v; }
-inline void     OrderAccess::release_store(volatile jlong*   p, jlong   v) { os::atomic_copy64(&v, p); }
-inline void     OrderAccess::release_store(volatile jubyte*  p, jubyte  v) { *p = v; }
-inline void     OrderAccess::release_store(volatile jushort* p, jushort v) { *p = v; }
-inline void     OrderAccess::release_store(volatile juint*   p, juint   v) { *p = v; }
-inline void     OrderAccess::release_store(volatile julong*  p, julong  v) { os::atomic_copy64(&v, p); }
-inline void     OrderAccess::release_store(volatile jfloat*  p, jfloat  v) { *p = v; }
-inline void     OrderAccess::release_store(volatile jdouble* p, jdouble v) { os::atomic_copy64(&v, p); }
+inline void     OrderAccess::release_store(volatile jbyte*   p, jbyte   v) { release(); *p = v; }
+inline void     OrderAccess::release_store(volatile jshort*  p, jshort  v) { release(); *p = v; }
+inline void     OrderAccess::release_store(volatile jint*    p, jint    v) { release(); *p = v; }
+inline void     OrderAccess::release_store(volatile jlong*   p, jlong   v)
+{ release(); os::atomic_copy64(&v, p); }
+inline void     OrderAccess::release_store(volatile jubyte*  p, jubyte  v) { release(); *p = v; }
+inline void     OrderAccess::release_store(volatile jushort* p, jushort v) { release(); *p = v; }
+inline void     OrderAccess::release_store(volatile juint*   p, juint   v) { release(); *p = v; }
+inline void     OrderAccess::release_store(volatile julong*  p, julong  v)
+{ release(); os::atomic_copy64(&v, p); }
+inline void     OrderAccess::release_store(volatile jfloat*  p, jfloat  v) { release(); *p = v; }
+inline void     OrderAccess::release_store(volatile jdouble* p, jdouble v)
+{ release(); os::atomic_copy64(&v, p); }

-inline void     OrderAccess::release_store_ptr(volatile intptr_t* p, intptr_t v) { *p = v; }
-inline void     OrderAccess::release_store_ptr(volatile void*     p, void*    v) { *(void* volatile *)p = v; }
+inline void     OrderAccess::release_store_ptr(volatile intptr_t* p, intptr_t v) { release(); *p = v; }
+inline void     OrderAccess::release_store_ptr(volatile void*     p, void*    v)
+{ release(); *(void* volatile *)p = v; }

 inline void     OrderAccess::store_fence(jbyte*   p, jbyte   v) { *p = v; fence(); }
 inline void     OrderAccess::store_fence(jshort*  p, jshort  v) { *p = v; fence(); }