On 19/08/2016 5:40 PM, Aleksey Shipilev wrote:
On 08/19/2016 10:13 AM, David Holmes wrote:
Now it might be cleaner to ditch Java version from Unsafe, and make
native entry points like Unsafe_CompareAnd{Exchange,Swap}{Byte,Short}
which would call relevant Atomic::cmpxchg-s.
I tried commenting out the Java-ish version and defining one that would
call Atomic::cmpxchg from unsafe.cpp in the VM. However something is
complaining about the intrinisics - I removed the
HotspotIntrinsicCandidate annotation as I don't want any intrinisics,
but I get a build error:
Compiler intrinsic is defined for method
[jdk.internal.misc.Unsafe.compareAndSwapByte(Ljava/lang/Object;JBB)Z],
but the method is not annotated with @HotSpotIntrinsicCandidate. Exiting.
No idea where this is coming from or how I can disable it ??
@HotSpotIntrinsicCandidate marks Java methods that are declared in
vmSymbols.hpp, and the VM code checks it. So, removing @HSIC without
modifying vmSymbols.hpp would blow up like that.
Anyway, I think you have to leave @HSIC methods untouched, because C2
would intrinsify them directly. To cater for the unsafe.cpp slow path,
do a separate method:
@HotSpotIntrinsicCandidate
public final byte compareAndExchangeByteVolatile(Object o, long offset,
byte expected,
byte x) {
compareAndExchangeByte0(o, long, expected, x);
}
public final native byte compareAndExchangeByte0(...);
...and then do an entry point for it in unsafe.cpp.
Okay that was the easy part.
Now where do I find out the conditional compilation syntax for the
X-VarHandle.java.template file?
Thanks,
David
Thanks,
-Aleksey
