RFR: CODETOOLS-7902854: jcstress: Print generated code assembly (optionally)

[Aleksey Shipilev]

Following up on test failures is hard without the generated code. Doing -XX:+PrintAssembly would print the generated code for everything, which would be unnecessarily noisy. Luckily, we can now instruct jcstress to dump the generated code for the hot loops only.

Sample output:

$ java -jar tests-custom/target/jcstress.jar -t UnfencedDekker -vv --jvmArgs "-XX:-TieredCompilation"
Java Concurrency Stress Tests
---------------------------------------------------------------------------------
Rev: 728c24c414d9b9c2, built by shade with 11.0.12-testing at 2021-03-18T15:36:51Z

Burning up to figure out the exact CPU count....... done!

Probing the target OS:
 (all failures are non-fatal, but may affect testing accuracy)

----- [OK] Trying to set affinity with taskset

Initializing and probing the target VM: 
 (all failures are non-fatal, but may affect testing accuracy)

----- [OK] Unlocking diagnostic VM options
----- [OK] Trimming down the default VM heap size to 1/64-th of max RAM
----- [OK] Trimming down the number of compiler threads
----- [OK] Trimming down the number of parallel GC threads
----- [OK] Trimming down the number of concurrent GC threads
----- [OK] Trimming down the number of G1 concurrent refinement GC threads
----- [OK] Testing @Contended works on all results and infra objects
----- [OK] Unlocking Whitebox API for online de-optimization: all methods
----- [OK] Unlocking Whitebox API for online de-optimization: selected methods
----- [OK] Unlocking C2 local code motion randomizer
----- [OK] Unlocking C2 global code motion randomizer
----- [OK] Unlocking C2 iterative global value numbering randomizer
----- [OK] Unlocking C2 conditional constant propagation randomizer
----- [OK] Testing allocation profiling
----- [OK] Testing Thread.onSpinWait
----- [OK] Testing PrintAssembly
----- [OK] Testing compiler directives

Probing what VM modes are available:
 (failures are non-fatal, but may miss some interesting cases)

----- [OK] [-XX:-TieredCompilation]

  Hardware CPUs in use: 64, using Thread.onSpinWait()
  Test preset mode: "default"
  Writing the test results to "jcstress-results-2021-03-18-16-37-38.bin.gz"
  Parsing results to "results/"
  Running each test matching "UnfencedDekker" for 1 forks, 5 iterations, 1000 ms each
  Solo stride size will be autobalanced within [10, 10000] elements, but taking no more than 100 Mb.

  Attached the non-interactive output stream.
  Printing the progress line at least every 15000 milliseconds.


      [OK] o.o.j.t.fences.UnfencedDekkerTest
    (fork: #1, JVM args: [-XX:-TieredCompilation])
  Observed state   Occurrences              Expectation  Interpretation                                              
            0, 0     8,376,544   ACCEPTABLE_INTERESTING  Acceptable with no sequential consistency enforced          
            0, 1   476,317,773               ACCEPTABLE  Acceptable under sequential consistency                     
            1, 0   218,828,395               ACCEPTABLE  Acceptable under sequential consistency                     
            1, 1           799               ACCEPTABLE  Acceptable under sequential consistency                     

    VM output stream: 
        
        ============================= C2-compiled nmethod ==============================
        ----------------------------------- Assembly -----------------------------------
        
        Compiled method (c2)     222  128 %           org.openjdk.jcstress.tests.fences.UnfencedDekkerTest_jcstress::run_actor1 @ 12 (55 bytes)
         total in heap  [0x00007f783863b110,0x00007f783863b7a8] = 1688
         relocation     [0x00007f783863b270,0x00007f783863b2a0] = 48
         main code      [0x00007f783863b2a0,0x00007f783863b5e0] = 832
         stub code      [0x00007f783863b5e0,0x00007f783863b5f8] = 24
         oops           [0x00007f783863b5f8,0x00007f783863b600] = 8
         metadata       [0x00007f783863b600,0x00007f783863b630] = 48
         scopes data    [0x00007f783863b630,0x00007f783863b6f8] = 200
         scopes pcs     [0x00007f783863b6f8,0x00007f783863b788] = 144
         dependencies   [0x00007f783863b788,0x00007f783863b790] = 8
         nul chk table  [0x00007f783863b790,0x00007f783863b7a8] = 24
        
        --------------------------------------------------------------------------------
        [Constant Pool (empty)]
        
        --------------------------------------------------------------------------------
        
        [Verified Entry Point]
          # {method} {0x00007f7825812658} 'run_actor1' '([Lorg/openjdk/jcstress/tests/fences/UnfencedDekkerTest;[Lorg/openjdk/jcstress/infra/results/II_Result;)V' in 'org/openjdk/jcstress/tests/fences/UnfencedDekkerTest_jcstress'
          0x00007f783863b2a0:   callq  0x00007f784a5a1120           ;   {runtime_call os::breakpoint()}
          0x00007f783863b2a5:   data16 data16 nopw 0x0(%rax,%rax,1)
          0x00007f783863b2b0:   mov    %eax,-0x14000(%rsp)
          0x00007f783863b2b7:   push   %rbp
          0x00007f783863b2b8:   sub    $0x40,%rsp
          0x00007f783863b2bc:   mov    0x40(%rsi),%r10
          0x00007f783863b2c0:   mov    %r10,(%rsp)
          0x00007f783863b2c4:   mov    0x28(%rsi),%rbp
  ...

-------------

Commit messages:
 - Helper class for verbosity levels
 - CODETOOLS-7902854: jcstress: Print generated code assembly (optionally)

Changes: https://git.openjdk.java.net/jcstress/pull/14/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jcstress&pr=14&range=00
  Issue: https://bugs.openjdk.java.net/browse/CODETOOLS-7902854
  Stats: 89 lines in 8 files changed: 72 ins; 2 del; 15 mod
  Patch: https://git.openjdk.java.net/jcstress/pull/14.diff
  Fetch: git fetch https://git.openjdk.java.net/jcstress pull/14/head:pull/14

PR: https://git.openjdk.java.net/jcstress/pull/14