proper usage of -XX:+PrintIdeal

Krystal Mok rednaxelafx at
Thu Nov 24 23:23:41 PST 2011

Hi Manohar,

You should probably post this to hotspot-compiler-dev, because these
debugging features were meant to be used by compiler developers.

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.

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?

- 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
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