RFR (M): 8149159: Clean up Unsafe

[Mikael Vidstedt]

There's are indentation changes of two of the backslashes for the 
JNI_ENTRY_NO_PRESERVE macro definition to align them with the other 
backslashes. I noticed that a similar change is needed for 
JNI_QUICK_ENTRY and JNI_LEAF. Arguably it should be done as a separate 
change, but I'm not sure it's worth the overhead...

Cheers,
Mikael

On 2016-02-18 13:52, Vladimir Kozlov wrote:
> Hotspot changes looks fine. Nice cleanup! What was changed in 
> interfaceSupport.hpp (it is empty in webrev)?
>
> Thanks,
> Vladimir
>
> On 2/18/16 11:22 AM, Mikael Vidstedt wrote:
>>
>> Please review the following change which does some relatively 
>> significant cleaning up of the Unsafe implementation.
>>
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8149159
>> Webrev (hotspot): 
>> http://cr.openjdk.java.net/~mikael/webrevs/8149159_unsafecleanup/hotspot/webrev.00/webrev/
>> Webrev (jdk): 
>> http://cr.openjdk.java.net/~mikael/webrevs/8149159_unsafecleanup/jdk/webrev.00/webrev/
>>
>> Summary:
>>
>> * To avoid code duplication sun.misc.Unsafe now delegates all work to 
>> jdk.internal.misc.Unsafe. This also means that the
>> VM - and unsafe.cpp specifically - no longer needs to know or care 
>> about s.m.Unsafe.
>> * The s.m.Unsafe delegation methods have all been decorated with 
>> @ForceInline to minimize the risk of performance
>> regressions, though it is highly likely that they will be inlined 
>> even without the annotations.
>> * The documentation has been updated to reflect that it is the 
>> responsibility of the user of Unsafe to make sure
>> arguments are valid.
>> * The argument checking has, to the extent possible, been moved from 
>> unsafe.cpp up to Java to simplify the native code
>> and allow the JIT to optimize it.
>> * Some of the argument checks have been relaxed. For example, the 
>> recently introduced U.copySwapMemory does not check
>> for null pointers anymore. See docs for j.i.m.U.checkPointer for the 
>> complete reasoning behind this. Note that the
>> Unsafe methods today, apart from U.copySwapMemory, do not perform the 
>> NULL related check(s).
>> * A test was added for j.i.m.U.copyMemory, based on U.copySwapMemory. 
>> Feel free to point out that I should merge them
>> (because I should).
>>
>> Also, unsafe.cpp was cleaned up rather dramatically. Some specific 
>> highlights:
>>
>> * Unsafe_ functions are now declared static, as are the other 
>> unsafe.cpp local functions.
>> * Created unsafe.hpp and moved some functions used in other parts of 
>> the VM to that. Removed some "extern" function
>> declarations (extern is bad, kittens die when extern is (over-)used).
>> * Remove scary looking comment about UNSAFE_LEAF not being possible 
>> to use - there's nothing special about it, it's just
>> a JVM_LEAF.
>> * Used UNSAFE_LEAF for a few simple leaf methods
>> * Added helpful braces around UNSAFE_ENTRY/UNSAFE_END to help 
>> auto-indent
>> * Removed unused Unsafe_<...>##140 functions/macros
>> * Updated macro argument names to be consistent throughout unsafe.cpp 
>> macro definitions
>> * Replaced some checks with asserts - as per above the checks are now 
>> performed in j.i.m.Unsafe instead.
>> * Removed all the s.m.Unsafe related code
>>
>>
>> Testing:
>>
>> * jtreg: hotspot_jprt group, jdk/internal
>> * JPRT: hotspot testset
>> * Perf: JMH unsafe-bench.jar (no significant changes)
>>
>> I'm taking suggestions on additional things to test.
>>
>> Cheers,
>> Mikael
>>