[11] RFR(S) 8205400: [Graal] compiler/jvmci/compilerToVM/DisassembleCodeBlobTest.java fails with can't be enqueued for compilation on level 4

[Vladimir Kozlov]

http://cr.openjdk.java.net/~kvn/8205400/webrev.00/
https://bugs.openjdk.java.net/browse/JDK-8205400

I was not able to reproduce the problem. I did 170 runs of the test with 
Graal in mach5. I can only speculate what happen.
By default JVMCI and Graal are initialized only on first tier4 
compilation request. Usually there are hot methods which trigger such 
compilation and initialization before the test requests compilation.

It is still possible that test's compilation request is the first.
The test asks blocking (BackgroundCompilation = false) compilation to 
wait when it complete [1].
But JVMCI code will unblock first compilation when JVMCI and Graal are 
not initialized yet [2].
As result execution continue before Graal's compilation finished (or 
even started) and WB::compile_method() will return NULL value.

To trigger eager JVMCI and Graal initialization flag -XX:+EagerJVMCI or 
-Xbatch (-XX:-BackgroundCompilation) should be used to run test. And 2 
of jvmci/compilerToVM/ tests which use the same WB compilation API are 
using -XX:-BackgroundCompilation. I am suggesting to do the same in 2 
other tests.

To find if this is really what happen I added error prints in 
WhiteBox::compile_method() which have several cases when it can return 
false.

Tested with tier1,tier2,tier3-graal,precheckin-comp

[1] 
http://hg.openjdk.java.net/jdk/jdk/file/d91a64467683/test/hotspot/jtreg/compiler/jvmci/compilerToVM/CompileCodeTestCase.java#l108
[2] 
http://hg.openjdk.java.net/jdk/jdk/file/d91a64467683/src/hotspot/share/compiler/compileBroker.cpp#l1082

-- 
Thanks,
Vladimir