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.