RFR (M): 8149159: Clean up Unsafe

[Vladimir Kozlov]

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
>