[9] RFR(S): 8046268: compiler/whitebox/ tests fail : must be osr_compiled

[dean long]

In the future, it might be useful for the whitebox interface to return a 
compilation count for a method.
That way we can query "is or was compiled" vs. "is currently compiled".

dl

On 10/3/2014 2:22 AM, Tobias Hartmann wrote:
> Hi,
>
> please review the following patch.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8046268
> Webrev: http://cr.openjdk.java.net/~thartmann/8046268/webrev.00/
>
> == Problem ==
> The whitebox tests assume that after the invocation of 
> 'CompilerWhiteBoxTest.compile()' the method is always compiled and 
> 'CompilerWhiteBoxTest.checkCompiled()' will return true. For OSR 
> compilations [1] this is does not hold. For example, in case of the 
> following events:
>
> 1) The test invokes 'CompilerWhiteBoxTest.compile()' to OSR compile 
> 'SimpleTestCase.Helper.osrMethod()'.
> 2) OSR compilation is performed at level 4. An uncommon trap is added 
> after the loop because profiling never reached that point. Execution 
> continues with the OSR version.
> 3) Deoptimization is triggered because the loop finishes (reason: 
> 'unstable if'). The OSR nmethod is made non-entrant and removed from 
> the OSR list (see 'nmethod::invalidate_osr_method').
> 4) The test uses CompilerWhiteBoxTest.checkCompiled() to make sure the 
> method is OSR compiled. Because the OSR nmethod was removed from the 
> list, check compiled returns false (see WB_IsMethodCompiled).
>
> This was caused by the fix for JDK-8030976 [2] because we now trust 
> the profile information more and add uncommon traps to untaken paths. 
> In this case we add an uncommon trap after the loop exit:
>
> private int osrMethod() {
>   int result = 0;
>   for (long i = 0; i < CompilerWhiteBoxTest.BACKEDGE_THRESHOLD; ++i) {
>     result += method();
>   }
>   return result;
> }
>
> == Solution ==
> I added code to 'warm up' the methods before triggering OSR 
> compilation by executing them a limited number of times. Like this, 
> the profile information marks the loop exit as taken and we don't add 
> an uncommon trap.
>
> == Testing ==
> - Executed failing tests on JPRT
>
> Thanks,
> Tobias
>
>
> [1] OSR compiled methods:
> compiler.whitebox.SimpleTestCase.Helper.OSR_CONSTRUCTOR
> compiler.whitebox.SimpleTestCase.Helper.OSR_METHOD
> compiler.whitebox.SimpleTestCase.Helper.OSR_STATIC
>
> [2] https://bugs.openjdk.java.net/browse/JDK-8030976