RFR: 8311279: TestStressIGVNAndCCP.java failed with different IGVN traces for the same seed

[Christian Hagedorn]

In `TestStressIGVNAndCCP`, we are executing a JVM twice and only want to compile and then run a single method `sum()`. The expectation is that we get the same output with `-XX:+TraceIterativeGVN`. However, our testing found a case where this did not match. When looking at the diff, I've noticed that with one JVM `sum()` had compile id 1, while the other JVM used compile id 2 for `sum()`. This makes a difference for the `debug_idx` which is printed for a dead node as "`compile id * 10000000000 + node index`":

Compile id 1:

80 Phi === _ _ _ [[ ]] [10000000080] ...

Compile id 2:

80 Phi === _ _ _ [[ ]] [20000000080] ...


I was not able to reproduce the original report but my suspicion is that one JVM additionally compiled a native method wrapper or a method handle intrinsic for some reason but the other one did not. This would explain the different compile id because we are should only compiling `sum()` with the given `CompileOnly` JVM flag. A native compilation can be triggered, for example, by passing additionally passing `-esa` with `CompileOnly`. We get compile id 3 for `sum()`:

     60 1 n java.lang.invoke.MethodHandle::invokeBasic()I (native)
     60 2 n java.lang.invoke.MethodHandle::linkToSpecial(LL)I (native) (static)
     69 3 b compiler.debug.TestStressIGVNAndCCP::sum (27 bytes)


To fix this, I suggest to use the `-XX:+CICountNative` flag which uses a separate counter for native compilations. Then, we'll always get compile id 1 for `sum()`:

     50 1 n java.lang.invoke.MethodHandle::invokeBasic()I (native)
     51 2 n java.lang.invoke.MethodHandle::linkToSpecial(LL)I (native) (static)
     59 1 b compiler.debug.TestStressIGVNAndCCP::sum (27 bytes)


This is the same approach as done in [JDK-8269342](https://bugs.openjdk.org/browse/JDK-8269342) to reliably crash with `-XX:CICrashAt=1` in the first non-native compilation.

Thanks,
Christian

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Commit messages:
 - 8311279: TestStressIGVNAndCCP.java failed with different IGVN traces for the same seed

Changes: https://git.openjdk.org/jdk/pull/14771/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14771&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311279
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/14771.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14771/head:pull/14771

PR: https://git.openjdk.org/jdk/pull/14771