[9] RFR(XXS): 8068661: Exclude compiler/whitebox/ForceNMethodSweepTest.java from nightly runs

[Albert Noll]

Hi,

this fix excludes compiler/whitebox/ForceNMethodSweepTest.java from the 
nightly runs.
The test is unstable for the following reasons:

A) The test is started with: 
-XX:CompileCommand=compileonly,SimpleTestCase$Helper::*
     As a result, all methods of SimpleTestCase$Helper can be compiled. 
These include the following accessor methods:
     SimpleTestCase$Helper.access$1400()I alive
     SimpleTestCase$Helper.access$1300(LSimpleTestCase$Helper;)I alive

     Since background compilation is enabled, it is possible that 
methods of the class SimpleTestCase$Helper are compiled just after (3) 
is executed.

     1) int afterCompilation = getTotalUsage();
     2) Asserts.assertGT(afterCompilation, usage, "compilation should 
increase usage");
     3) guaranteedSweep();
     4) int afterSweep = getTotalUsage();
     5) Asserts.assertLTE(afterSweep, afterCompilation, "sweep shouldn't 
increase usage");

B) Another possible problem is that we have class loading in (2). Since 
adapters are created eagerly, there is a potential allocation in the 
code cache for adapters. In the executions I observed, this was not a 
problem due to adapter sharing (there already exists an adapter, since a 
class that contains a method with the same signature was loaded before). 
However, there is no guarantee that adapter sharing will also make this 
test work in the future.

Here is the webrev:
http://cr.openjdk.java.net/~anoll/8068661/webrev.00/

Thanks,
Albert