proper usage of -XX:+PrintIdeal

Manohar Jonnalagedda manojo10386 at
Fri Nov 25 02:12:33 PST 2011

Hi Krystal,

thanks for the reply. I will post this on the hotspot-compiler-dev list as
well. Here is the link :

> Your command line arguments looks okay to me. I tried it on a fastdebug
> build of HotSpot 20.0-b11 and it worked fine. Is it that the file.xml is
> empty, or is it the particular method that you're after doesn't exist in
> "file.xml"? For the latter case, did you see a "file1.xml" in the same
> directory? Does it contain the method you're after?

I am using 20.0-b17 of the fastdebug build. I do have two files as well,
file.xml and file1.xml, and neither contain the method I am looking for. I
only have details for 4 methods, one of them being a decodeArrayLoop and
the others being methods from the API (file input and string manipulation
methods). Is it possible that methodA would not be JIT compiled following
the extra instrumentation overhead?


> - Kris
> On Fri, Nov 25, 2011 at 12:57 AM, Manohar Jonnalagedda <
> manojo10386 at> wrote:
>> Hello all,
>> I am new to using the debug features of hotspot (probably posting to the
>> wrong list, as I haven't seen any list targetted to hotspot users), and was
>> interested in checking out the graph of a program that I wrote. The program
>> contains a method 'methodA' which I would like to inspect in terms of
>> optimizations performed. I verified using the PrintCompilation (and
>> PrintAssembly) flag that it was indeed JIT compiled.
>> When I use the PrintIdeal flags, however, my output xml files do not
>> contain any mention of this method. Here is the command I use :
>> $JAVA_HOME/bin/java -verbose:gc -server -d64 -XX:+UseCompressedOops
>> -XX:+DoEscapeAnalysis -XX:PrintIdealGraphLevel=1
>> -XX:PrintIdealGraphFile="file.xml" -XX:+PrintIdeal $JAVA_OPTS "$@"
>> Would the problem be due to not using the flags properly?
>> Thanks a lot for your help,
>> Manohar
> What version of HotSpot are you using? And, I assume you are using a
fastdebug build, right? Otherwise the PrintIdeal* arguments won't even be
accepted at VM start.
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