System.arraycopy

[Deneau, Tom]

for now everything in hsail has to be inlined, but I guess we can postpone support for the "hard" generic cases until we can call stubs.

-- Tom D.

> -----Original Message-----
> From: Tom Rodriguez [mailto:tom.rodriguez at oracle.com]
> Sent: Monday, June 09, 2014 5:28 PM
> To: Deneau, Tom
> Cc: Chris Thalinger; graal-dev at openjdk.java.net
> Subject: Re: System.arraycopy
> 
> On Jun 9, 2014, at 8:24 AM, Deneau, Tom <tom.deneau at amd.com> wrote:
> 
> > I did some tweaking to our HSAILHotSpotReplacementsImpl to basically
> make it always use the non-foreign-call version (UnsafeArrayCopy) rather
> than the foreign-call version, regardless of the sense of the global
> flag CallArrayCopy.  This seems to  cover most of the arraycopy cases.
> >
> > The one case that this not handle is a "non-exact" Object Array copy,
> for instance copying and array of Strings to an array of Objects.
> 
> That case could be handled with the existing code by improving the store
> check.  Currently it tests that the hubs are equal but for arrays the
> requirement is really that the element type of the destination is
> assignable from the source element type.  So copying from String[] to
> Object[] doesn't require any per element checks but the reverse
> operation does.  UnsafeArrayCopyNode doesn't do that great a job of
> decomposing the interesting cases for Object copies.  Also the generic
> code doesn't handle conjoint copies either which is fairly common.
> 
> >
> > I see the snippet code for this "generic array copy" does as shown
> > below and I believe we are taking the genericObjectCallCounter path.
> > So we still fail with
> >
> >  com.oracle.graal.graph.GraalGraphInternalError
> com.oracle.graal.compiler.common.GraalInternalError: unimplemented
> > 	at node: 78|Invoke#Direct#System.arraycopy
> >
> > (I guess this doesn't get replaced by a snippet since it is already in
> a snippet?
> >
> > So my question is:  Is there any java implementation of this path?  Or
> any solution that would not involve a foreign call, etc.
> 
> A full implementation of array copy isn't that hard in Java but it will
> entail a large amount of code.  Would it be possible call HSAIL stubs
> for doing the copies or does everything have to be inline?
> 
> tom
> 
> >
> > -- Tom
> >
> > =================
> >    @Snippet
> >    public static void arraycopy(Object src, int srcPos, Object dest,
> int destPos, int length) {
> >        Object nonNullSrc = guardingNonNull(src);
> >        Object nonNullDest = guardingNonNull(dest);
> >        Word srcHub = loadHub(nonNullSrc);
> >        Word destHub = loadHub(nonNullDest);
> >        if (probability(FAST_PATH_PROBABILITY, srcHub.equal(destHub))
> && probability(FAST_PATH_PROBABILITY, nonNullSrc != nonNullDest)) {
> >            int layoutHelper = checkArrayType(srcHub);
> >            final boolean isObjectArray = ((layoutHelper &
> > layoutHelperElementTypePrimitiveInPlace()) == 0);
> >
> >            checkLimits(nonNullSrc, srcPos, nonNullDest, destPos,
> length);
> >            if (probability(FAST_PATH_PROBABILITY, isObjectArray)) {
> >                genericObjectExactCallCounter.inc();
> >                UnsafeArrayCopyNode.arraycopy(nonNullSrc, srcPos,
> nonNullDest, destPos, length, Kind.Object);
> >            } else {
> >                genericPrimitiveCallCounter.inc();
> >                UnsafeArrayCopyNode.arraycopyPrimitive(nonNullSrc,
> srcPos, nonNullDest, destPos, length, layoutHelper);
> >            }
> >        } else {
> >            genericObjectCallCounter.inc();
> >            System.arraycopy(nonNullSrc, srcPos, nonNullDest, destPos,
> length);
> >        }
> >    }
> >
> >
> >> -----Original Message-----
> >> From: Deneau, Tom
> >> Sent: Thursday, June 05, 2014 6:29 PM
> >> To: 'Tom Rodriguez'
> >> Cc: Chris Thalinger; graal-dev at openjdk.java.net
> >> Subject: RE: System.arraycopy
> >>
> >> Using -G:-CallArrayCopy seemed to work...
> >>
> >>> -----Original Message-----
> >>> From: Tom Rodriguez [mailto:tom.rodriguez at oracle.com]
> >>> Sent: Thursday, June 05, 2014 4:44 PM
> >>> To: Deneau, Tom
> >>> Cc: Chris Thalinger; graal-dev at openjdk.java.net
> >>> Subject: Re: System.arraycopy
> >>>
> >>>
> >>> On Jun 5, 2014, at 2:39 PM, Deneau, Tom <tom.deneau at amd.com> wrote:
> >>>
> >>>> Christian --
> >>>>
> >>>> For now just going for functionally correct, will address
> >>>> performance
> >>> issues in the future.  But yes there are vector instructions that
> >>> could help even in a single workitem.
> >>>>
> >>>> Is there already a pure java implementation of System.arrayCopy we
> >>> could substitute?
> >>>
> >>> UnsafeArrayCopyNode is pretty much that.  The flag CallArrayCopy
> >>> controls whether it prefers the hotspot stubs for array copy or not
> >>> but it should be able to fall back to UnsafeArrayCopyNode.
> >>>
> >>> tom
> >>>
> >>>>
> >>>> I guess we would want to use the logic to do different
> >>>> substitutions
> >>> based on the type of the array (like in ArrayCopySnippets)?
> >>>>
> >>>> any other advice for implementing this?
> >>>>
> >>>> -- Tom
> >>>>
> >>>>
> >>>>
> >>>>> -----Original Message-----
> >>>>> From: Christian Thalinger [mailto:christian.thalinger at oracle.com]
> >>>>> Sent: Thursday, June 05, 2014 3:45 PM
> >>>>> To: Deneau, Tom
> >>>>> Cc: graal-dev at openjdk.java.net
> >>>>> Subject: Re: System.arraycopy
> >>>>>
> >>>>> Well, I guess the easiest but maybe not most performant way would
> >>>>> be to have a substitution and implement it in plain Java.
> >>>>>
> >>>>> On the other hand you could rely on vectorization and the power of
> >>>>> GPUs to produce good, parallel code :-)
> >>>>>
> >>>>> On Jun 5, 2014, at 1:29 PM, Deneau, Tom <tom.deneau at amd.com>
> wrote:
> >>>>>
> >>>>>> Since we cannot handle "foreign calls" in the hsail backend, what
> >>>>>> is
> >>>>> the preferred way to implement System.arraycopy?  Right now, we
> >>>>> are deferring to the host and so getting an ArrayCopyCallNode
> >>>>> which gets lowered to a graph containing a ForeignCallNode.
> >>>>>>
> >>>>>> I confess to being a little confused with the ArrayCopyNode and
> >>>>> Snippets, UnsafeArrayCopyNode and Snippets, ArrayCopyCallNode,
> etc.
> >>>>>>
> >>>>>> -- Tom
> >>>>>>
> >>>>
> >