RFR: Make Zero build and run with JDK8

[Roman Kennke]

Am Mittwoch, den 17.10.2012, 14:40 -0700 schrieb Christian Thalinger:
> On Oct 16, 2012, at 8:01 AM, Roman Kennke <rkennke at redhat.com> wrote:
> 
> > Hi Christian,
> > 
> >>>>>> In the recent weeks I worked on the Zero interpreter, to get it to build
> >>>>>> and run with JDK8, and in particular with the latest changes that came
> >>>>>> from mlvm (meth-lazy). The following webrev applies to hsx/hotspot-main:
> >>>>>> 
> >>>>>> http://cr.openjdk.java.net/~rkennke/zerojdk8/webrev.00/
> >>>> 
> >>>> src/share/vm/asm/codeBuffer.cpp:
> >>>> 
> >>>> -  if (dest->blob() == NULL) {
> >>>> +  if (dest->blob() == NULL && dest_filled != 0x0) {
> >>>> 
> >>>> Do we really need this when you have this:
> >>> 
> >>> The above is needed, because the loop above it that initializes
> >>> dest_filled is never executed. However, I will change the test to
> >>> dest_filled != NULL :-)
> >>> 
> >>>> static void pd_fill_to_bytes(void* to, size_t count, jubyte value) {
> >>>> 
> >>>> -  memset(to, value, count);
> >>>> +  if ( count > 0 ) memset(to, value, count);
> >>>> 
> >>>> }
> >>> 
> >>> Turns out that this is 1. not related to the other change above and 2.
> >>> not needed. I'll remove it.
> >>> 
> >>>> src/share/vm/interpreter/interpreter.cpp:
> >>>> 
> >>>> -  assert(_entry_table[kind] == _entry_table[abstract], "previous value must be AME entry");
> >>>> +  assert(_entry_table[kind] == NULL || _entry_table[kind] == _entry_table[abstract], "previous value must be AME entry or NULL");
> >>>> 
> >>>> Why did you need that change?
> >>> 
> >>> Apparently, before the whole table was initialized, and the methodhandle
> >>> related entries left as abstract. Now the methodhandle entries are
> >>> simply left to NULL. I suppose we could change the assert to 
> >>> 
> >>> assert(_entry_table[kind] == NULL, "previous value must be NULL");
> >>> 
> >>> Alternatively, we could fix the code that puts the other entries to also
> >>> set the methodhandle entries to AME and go back to the original assert.
> >>> What do you think?
> >> 
> >> TemplateInterpreterGenerator::generate_all sets all MH entries to AME:
> >> 
> >>  // method handle entry kinds are generated later in MethodHandlesAdapterGenerator::generate:                                                                  
> >>  for (int i = Interpreter::method_handle_invoke_FIRST; i <= Interpreter::method_handle_invoke_LAST; i++) {                                                      
> >>    Interpreter::MethodKind kind = (Interpreter::MethodKind) i;                                                                                                  
> >>    Interpreter::_entry_table[kind] = Interpreter::_entry_table[Interpreter::abstract];                                                                          
> >>  }                                                                                                                                                              
> >> 
> >> You need similar code in Zero.
> > 
> > Alright, I extracted this piece of code into a separate protected method
> > void AbstractInterpreterGenerator::initializeMethodHandleEntries() and
> > call it both from templateInterpreter and cppInterpreter to initialize
> > the method handle entries to AME.
> > 
> > This new webrev also reverts this:
> > 
> >>> static void pd_fill_to_bytes(void* to, size_t count, jubyte value) {
> >>>> 
> >>>> -  memset(to, value, count);
> >>>> +  if ( count > 0 ) memset(to, value, count);
> >>>> 
> >>>> }
> >> 
> > 
> > .. and changes the 0x0 to NULL here:
> > 
> > 
> >>> src/share/vm/asm/codeBuffer.cpp:
> >>>> 
> >>>> -  if (dest->blob() == NULL) {
> >>>> +  if (dest->blob() == NULL && dest_filled != 0x0) {
> >>>> 
> >> 
> > 
> > I tried JRuby a little more and verified that it's actually using +indy,
> > and it works all well.
> > 
> > http://cr.openjdk.java.net/~rkennke/zerojdk8/webrev.01/
> 
> It seems this webrev contains the old changes.

Arg! I did the changes in my hotspot-comp tree then made the webrev in
my hotspot-main :-) Here's the correct one:

http://cr.openjdk.java.net/~rkennke/zerojdk8/webrev.02/

Cheers,
Roman