MVT-based vectors: first stab

[Tobias Hartmann]

Hi Vladimir,

thanks a lot for the nice summary! I think it would makes sense to file enhancements/bugs for the individual issues.

On 28.06.2017 15:17, Vladimir Ivanov wrote:
> I hit some bugs along the way

I had a closer look and (as you already figured out) one problem is that typeflow analysis incorrectly sets the type of a PhiNode to TypeValueType instead of TypeValueTypePtr for __Value. When inlining a method handle intrinsic in CallGenerator::for_method_handle_inline() we should cast all arguments to their actual types but we miss the PhiNode because it's already of TypeValueType:

t: <ciValueKlass name=valhalla/vector/Long2$Value loader=0x00000006d8776320 loaded=true initialized=true finalized=false subklass=false size=32 flags=public,final,super super=java/lang/__Value ident=1108 address=0x00007f218008e270>
arg_type: valuetype[0]:{empty}
sig_type: valuetype* valhalla/vector/Long2$Value:NotNull
arg: 659	Phi	===  652 _  626  [[ 616  662  678  680  684  730  760  785  790  793  837  867  874  889  891  894 ]]  #valuetype[0]:{empty} !jvms: 1310540333::invoke @ bci:170 858242339::invokeExact_MT @ bci:19 VectorTest::acc @ bci:4 VectorTest::main @ bci:69

We then fail in Parse::do_vunbox because the input node is a Phi (and not a ValueTypeNode).

I think in addition to the fix in type.cpp, we should add this assert to catch such problems in the future:

--- old/src/share/vm/opto/callGenerator.cpp	2017-06-28 15:25:40.812039870 +0200
+++ new/src/share/vm/opto/callGenerator.cpp	2017-06-28 15:25:40.720039875 +0200
@@ -896,10 +896,11 @@
   if (t->is_valuetype()) {
     assert(!(arg_type->isa_valuetype() && t == kit.C->env()->___Value_klass()), "need a pointer to the value type");
     if (arg_type->isa_valuetypeptr() && t != kit.C->env()->___Value_klass()) {
-      const Type* sig_type = TypeOopPtr::make_from_klass(t->as_klass());
       Node* cast = gvn.transform(new CheckCastPPNode(kit.control(), arg, sig_type));
       Node* vt = ValueTypeNode::make(gvn, kit.merged_memory(), cast);
       kit.set_argument(arg_nb, vt);
+    } else {
+      assert(t == kit.C->env()->___Value_klass() || arg->is_ValueType(), "inconsistent argument");
     }
   } else {
     if (arg_type->isa_oopptr() && !arg_type->higher_equal(sig_type)) {

I'll take the chance to look at the method handle implementation in a bit more detail and try to come up with a regression test for this to extend our ValueTypesTestBench.

Best regards,
Tobias