merge vm_version_x86_{32,64}.hpp

[Christian Thalinger]

On Mon, 2009-02-23 at 08:49 +0100, Christian Thalinger wrote:
> On Mon, 2009-02-23 at 10:10 +1000, David Holmes - Sun Microsystems
> wrote:
> > Hi Vladimir,
> > 
> > Christian's proposal was to take the existing four files:
> > 
> >  > vm_version_x86_32.cpp, vm_version_x86_32.hpp,
> >  > vm_version_x86_64.cpp, vm_version_x86_64.hpp
> > 
> > and to factor out the common code into:
> > 
> >  > vm_version_x86.cpp and vm_version_x86.hpp
> > 
> > the question asked was then whether to deal with the platform specific 
> > code by:
> > 
> > a) keeping the existing 4 files in addition to the 2 new ones (assuming 
> > all four are still needed); or
> > 
> > b) use ifdef's in the new files and discard the 4 old ones

Okay, there are way too less differences to keep the old specific files
around.  There are only two differences I'm not sure about:

@@ -418,31 +355,32 @@
 
   if( AllocatePrefetchStyle == 2 && is_intel() &&
       cpu_family() == 6 && supports_sse3() ) { // watermark prefetching on Core
-    AllocatePrefetchDistance = 320;
+    AllocatePrefetchDistance = 384;
   }
   assert(AllocatePrefetchDistance % AllocatePrefetchStepSize == 0, "invalid value");
 
+  // Prefetch settings
+  PrefetchCopyIntervalInBytes = prefetch_copy_interval_in_bytes();
+  PrefetchScanIntervalInBytes = prefetch_scan_interval_in_bytes();
+  PrefetchFieldsAhead         = prefetch_fields_ahead();
+

For the first one, I'm not sure which value to choose or if they should
be different on 32 and 64-bit?

And the second, I'm not sure I can set them on 32-bit.  Per default
these are -1.

Besides that, there's only one real difference:

+  // OS should support SSE for x64 and hardware should support at least SSE2.
+  if (!VM_Version::supports_sse2()) {
+    vm_exit_during_initialization("Unknown x64 processor: SSE2 not supported");
   }

Is that check really necessary on x64?  If so, I simply put it inside an
#ifdef.

-- Christian