RFR(XS): 8049441: PPC64: Don't use StubCodeMarks for zero-length stubs

[Daniel D. Daugherty]

Adding the Serviceability Team since JVM/TI belongs to them.

Dan


On 7/8/14 9:41 AM, Volker Simonis wrote:
> Hi,
>
> could somebody please review and push the following small, PPC64-only
> change to any of the hs team repositories:
>
> http://cr.openjdk.java.net/~simonis/webrevs/8049441/
> https://bugs.openjdk.java.net/browse/JDK-8049441
>
> Background:
>
> For some stubs we actually do not really generate code on PPC64 but
> instead we use a native C-function with inline-assembly. If the
> generators of these stubs contain a StubCodeMark, they will trigger
> JvmtiExport::post_dynamic_code_generated_internal events with a zero
> length code size. These events may fool clients like Oprofile which
> register for these events (thanks to Maynard Johnson who reported this
> - see http://mail.openjdk.java.net/pipermail/ppc-aix-port-dev/2014-June/002032.html).
>
> This change simply removes the StubCodeMark from
> ICacheStubGenerator::generate_icache_flush() and generate_verify_oop()
> because they don't generate assembly code. It also removes the
> StubCodeMark from generate_throw_exception() because it doesn't really
> generate a plain stub but a runtime stub for which the JVMT dynamic
> code event is already generated by RuntimeStub::new_runtime_stub() ->
> CodeBlob::trace_new_stub() ->
> JvmtiExport::post_dynamic_code_generated().
>
> Thank you and best regards,
> Volker