Has --dump-debug-dir behaviour changed in JDK9?

A. Sundararajan sundararajan.athijegannathan at oracle.com
Wed Jun 10 04:22:47 UTC 2015


Filed a bug to track for future reference: 

Actually, this is not a bug. Two things:

1) --compile-only / -co option is no longer mandatory to use 
--debug-dump-dir option/
2) optimistic types is off by default in jdk8u and it is on by default 
with jdk9.

With optimistic types, code generation is lazier & optimistic -- code is 
generated/re-generated as you run the code. With jdk9, you can either

1) Turn off optimistic types with jdk9 (using -ot=false option) and dump 
similar code as in jdk8u
2) or run the code (i.e., remove -co / --compile-only option) and get 
all generated (and regenerated) code dumped.

PS. I've resolved the bug as "not an issue".

Hope this explains,

On Wednesday 10 June 2015 02:55 AM, Chris Newland wrote:
> Hi,
> Has Nashorn's behaviour for dumping bytecode changed in JDK9?
> Given this JavaScript:
> https://gist.github.com/chriswhocodes/bfe139592adb846967d8
> Executed using
> $JAVA_HOME/bin/jjs -co --dump-debug-dir=. run.js
> Under 8u60b18 the bytecode is produced as expected:
> https://gist.github.com/chriswhocodes/e3a85c3613b084e45356
> This visualises correctly in JITWatch[1] and the bytecode maps back to the
> source as expected.
> But under 9b67 only a small amount of bytecode is output that doesn't
> represent the source program:
> https://gist.github.com/chriswhocodes/c6c6e33e7994c98d4975
> The correct program output is produced under both executions so I don't
> think the difference is down to dead code elimination.
> Possible regression?
> Thanks,
> Chris
> @chriswhocodes
> [1] https://github.com/AdoptOpenJDK/jitwatch

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