1 # Overview

     2 

     3 The Ideal Graph Visualizer is a tool developed to help examine the intermediate

     4 representation of C2 which is commonly referred to as the "ideal graph". It was

     5 developed in collaboration with the University of Linz in Austria and has been

     6 included as part of hotspot since that was the primary target of the tool. The

     7 tool itself is fairly general with only a few modules that contain C2 specific

     8 elements.

     9 

    10 The tool is built on top of the NetBeans 7 rich client infrastructure and so

    11 requires NetBeans to build. It currently requires at least Java 6 to run as it

    12 needs support for JavaScript for its filtering mechanism and assumes it's built

    13 into the platform.  It should build out of the box with NetBeans 7.0 and Java 6

    14 or later.

    15 

    16 # Building and Running

    17 

    18 The build system used for IGV is ant. To download all required libraries and

    19 build IGV, issue `ant build`. To run IGV, use the `igv.sh` command; it will put

    20 all log messages generated by the run to the file `.igv.log`. To see all log

    21 messages generated during an IGV run, use `ant run`.

    22 

    23 # Usage

    24 

    25 The JVM support is controlled by the flag `-XX:PrintIdealGraphLevel=#` where `#`

    26 is:

    27 

    28 * 0: no output, the default

    29 * 1: dumps graph after parsing, before matching, and final code (also dumps

    30      graphs for failed compilations, if available)

    31 * 2: more detail, including after loop opts

    32 * 3: even more detail

    33 * 4: prints graph after parsing every bytecode (very slow)

    34 

    35 By default the JVM expects that it will connect to a visualizer on the local

    36 host on port 4444. This can be configured using the options

    37 `-XX:PrintIdealGraphAddress=` and `-XX:PrintIdealGraphPort=`.

    38 `PrintIdealGraphAddress` can actually be a hostname.

    39 

    40 It is advisable to run the JVM with background compilation disabled (-Xbatch).

    41 Compilations going on in the background may be cancelled when the VM terminates,

    42 which can lead to incomplete dumps being sent to IGV.

    43 

    44 Alternatively the output can be sent to a file using

    45 `-XX:PrintIdealGraphFile=filename`. Each compiler thread will get it's own file

    46 with unique names being generated by adding a number onto the provided file

    47 name.

    48 

    49 More information about the tool is available at

    50 https://wikis.oracle.com/display/HotSpotInternals/IdealGraphVisualizer.