Release store in C2 putfield

[Vladimir Kozlov]

In general I am fine with such platform specific change in shared code.

But in current case non-volatile release_store code affects only PPC64. 
As Aleksey suggested may be we should use NOT_PPC64() macro instead.
Also I don't see calls as_Store()->is_unordered() in ppc.ad file. Looks 
like PPC64 doesn't check this flag.

Thanks,
Vladimir

On 9/3/14 11:16 AM, Andrew Haley wrote:
> On 09/03/2014 06:21 PM, Vladimir Kozlov wrote:
>> Andrew,
>>
>> Do you need unordered in Parse::array_store() too?
>
> Yes.
>
>> Another way of doing it is to define MemNode::release_if_reference() in .ad files in 'source %{' section.
>
> Yes, that's what we've got now.  Thanks.
>
> Andrew.
>
>
> # HG changeset patch
> # User Edward Nevill edward.nevill at linaro.org
> # Date 1409307165 -3600
> #      Fri Aug 29 11:12:45 2014 +0100
> # Node ID fc245bc14fa3589074c78ceb0e25ecf36ee3e110
> # Parent  32fae3443576ac6b4b5ac0770c0829ce6c08764e
> Dont use a release store when storing an OOP in a non-volatile field.
>
> diff -r 32fae3443576 -r fc245bc14fa3 src/share/vm/opto/memnode.hpp
> --- a/src/share/vm/opto/memnode.hpp	Mon Sep 01 13:10:18 2014 -0400
> +++ b/src/share/vm/opto/memnode.hpp	Fri Aug 29 11:12:45 2014 +0100
> @@ -503,6 +503,12 @@
>     // Conservatively release stores of object references in order to
>     // ensure visibility of object initialization.
>     static inline MemOrd release_if_reference(const BasicType t) {
> +    // AArch64 doesn't need a release store because if there is an
> +    // address dependency between a read and a write, then those
> +    // memory accesses are observed in program order by all observers
> +    // within the shareability domain.
> +    AARCH64_ONLY(return unordered);
> +
>       const MemOrd mo = (t == T_ARRAY ||
>                          t == T_ADDRESS || // Might be the address of an object reference (`boxing').
>                          t == T_OBJECT) ? release : unordered;
> diff -r 32fae3443576 -r fc245bc14fa3 src/share/vm/opto/parse2.cpp
> --- a/src/share/vm/opto/parse2.cpp	Mon Sep 01 13:10:18 2014 -0400
> +++ b/src/share/vm/opto/parse2.cpp	Fri Aug 29 11:12:45 2014 +0100
> @@ -1689,7 +1689,7 @@
>       a = pop();                  // the array itself
>       const TypeOopPtr* elemtype  = _gvn.type(a)->is_aryptr()->elem()->make_oopptr();
>       const TypeAryPtr* adr_type = TypeAryPtr::OOPS;
> -    Node* store = store_oop_to_array(control(), a, d, adr_type, c, elemtype, T_OBJECT, MemNode::release);
> +    Node* store = store_oop_to_array(control(), a, d, adr_type, c, elemtype, T_OBJECT, StoreNode::release_if_reference(T_OBJECT));
>       break;
>     }
>     case Bytecodes::_lastore: {
>