On Feb 9, 2014, at 1:52 PM, Remi Forax <fo...@univ-mlv.fr> wrote: > On 02/08/2014 06:52 PM, Brian Goetz wrote: >>> can you be a little more specific and provide the way >>> foo.volatile.compareAndSet is compiled with this example: >> >> Hey, the JEP isn't even out of draft yet! Stop asking hard questions. > > :) > >> >> The current strawman, though, is to expose direct (CP-ready) MH forms >> (Lookup API / constant pool format TBD) for field get/set with fence, array >> element get/set with fence, field CAS, and array element CAS. Then the >> static compiler translates >> >> foo.volatile.cAS(n,m) >> >> as >> >> LDC #MH[lookupFieldCASer(foo)] >> aload n >> aload m >> invokevirtual "invokeExact" > > wow, you bring out the big guns ! > > I see a big issue with this approach, it requires to change the JVM spec each > time you want to add a new operation. >
Yes, although realistically i would expect new operations only to be added with each major release. > Moreover, overloads of LDC are usually re-written by JVMs has private > opcodes, so why not directly use new opcodes, > it will take less space in the classfile too. > More work than expanding the kinds of method handle? I have not looked at this in detail but perhaps there might be a few new reference_kind items (for get/put/static fields) that can refer to a new constant pool entry consisting of a pair of CONSTANT_Fieldref_info and CONSTANT_InterfaceMethodref_info for VirtualXXX iface? Paul.
