RFR: JDK-8199735: Mark word updates need to use Access API

[Roman Kennke]

Hi Erik,

Thanks for having a look.

> A few comments:
> 
> 1) Please make sure all files referencing these accessors that have been
> moved to the oop.inline.hpp file now #include the oop.inline.hpp file. I
> found that there are quite a few missing by looking for references to
> oopDesc::mark() with rtags.
> 2) I think the mark_addr() function should now be called mark_addr_raw()
> for consistency.
> 3) I wonder if there should be _raw() accessors that the GCs use
> instead. It feels like the GC should not go through the Access API to
> acquire mark words.

You are of course right in all 3 points. Unfortunately, that causes
massive ripples through the code base ;-)

So here is what I did: I added _raw() variants for stuff that is used by
GC. I temporarily renamed all relevant methods, e.g. mark() ->
mark_fluff() to make the compiler help me. Then for each occurance of
any such call decided whether it should call the usual method, or the
raw variant (as a general rule, everything under src/hotspot/share/gc
uses the _raw() variants). Also, I added #include "oop.inline.hpp" for
every such occurance. Then I renamed all _fluff() methods and calls back
to usual. Did this exercise with and without PCH, with and without zero.
Checked with grep if I might have missed some.

Notes: bytecodeInterpreter.cpp needed some additional fixes to use
cas_set_mark() instead of the Atomic::cmpxchg().

There are a bunch of methods in oop.hpp that are only used by GC, like
is_locked() etc. I haven't changed them to _raw().

This passes tier1 tests release+fastdebug, and as mentioned above builds
with and without PCH and zero.

Differential:
http://cr.openjdk.java.net/~rkennke/JDK-8199735/webrev.03.diff/
Full:
http://cr.openjdk.java.net/~rkennke/JDK-8199735/webrev.03/

Better now?

Best regards,
Roman



> 
> Thanks,
> /Erik
> 
> 
> On 2018-03-21 20:21, Roman Kennke wrote:
>> Am 19.03.2018 um 12:07 schrieb Roman Kennke:
>>> Am 19.03.2018 um 11:40 schrieb Roman Kennke:
>>>> Currently, the mark word is accessed directly in oopDesc::mark()
>>>> set_mark() and a bunch of other accessors. Those need to use the Access
>>>> API instead because GC might want to employ barriers on those accesses,
>>>> pretty much like every other field in oopDesc.
>>>>
>>>> Notice that this is *not* about accessing the bits and fields inside
>>>> the
>>>> markOop, but about accessing the header itself.
>>>>
>>>> http://cr.openjdk.java.net/~rkennke/JDK-8199735/webrev.01/
>>>>
>>>> Testing: build fastdebug/release with and without PCH, passed tier1
>>>> fastdebug/release.
>>>>
>>>> Can I please get reviews?
>>>>
>>>> Thanks, Roman
>>>>
>>> Just when I sent it, I realized that this is dropping the volatile from
>>> the mark word access. Fixed here:
>>>
>>>
>>> http://cr.openjdk.java.net/~rkennke/JDK-8199735/webrev.02/
>>>
>> Ping?
>>
> 


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