Combining Static and Dynamic Data in Code Visualization

David EngSable Research Group, McGill UniversityPASTE 2002Charleston, South CarolinaNovember 18-19, 2002

Presentation outline Introduction Framework overview JIL SOOT STEP JIMPLEX Future work

Introduction Code visualization: why and where?

Program understanding. Compiler development. Visualization of an optimizable IR.

Motivation: Expose both static & dynamic program

attributes which are hidden in the raw IR. Design goals:

Intuitive, portable, & modular.

Framework overview

Java class files

MyClass.java

JVM/JVMPI(execution

profile)

Tools with JIL support

Visualizers with JIL supportJIL documents

SOOT

STEP

static data(JIL)

dynamic data(JIL)

JIMPLEX(XSL/HTML)

MyVisualizer(my language)

DTD

DTD

(d)(c)(b)(a)

Java Intermediate Language (JIL)

XML-based representation of code. A metalanguage used to describe

other languages and their characteristics.

Encapsulates IRs as code objects which can be extended with both static and dynamic data.

JIL document structure

contributing toolsruntime accessesruntime invokes

name, returns, access

invoke targets

definitions

usesuses

name, type, access version, created

myclass

historyfields

name, type

parameters

name, type

locals

statement count

name

labels

live variables in/out

flow information

jimple declaration

line number, label

statements

type, handler

exceptions

methods

myclass

extension

base

element legend

required

Benefits of using XML Extensible: add or remove elements

without breaking existing structure. Supported by existing parsers, APIs,

software, databases, servers, etc. Portable across platforms and

networks. Human readable, editable.

JIL Let’s take a look at an example JIL

document…

Static vs. dynamic data Static data:

Collected at compile-time Program attributes Flow information Analysis results Basis for program understanding

We chose SOOT as a source of static data…

SOOT Java optimization framework and API. Uses intermediate languages (IRs) to perform

analyses and transformations. Provides several output formats, including JIL.

Jimple source(.jimple)

SOOTJava source(.java)

Java class(.class)

JIL document(.xml)

Baf, Grimp,and Jimple

analysis & optimization

Grimp source(.grimp)

Baf source(.baf)

javac

SOOT as a source of JIL SOOT was modified to generate

Jimple as XML. The resulting XML contains general

program characteristics and flow information.

Static analysis results can be linked to applicable code elements.

SOOT elements in JIL As a source of static data:

Flow information Live variable analysis Variable uses and definitions Class hierarchy analysis Variable type analysis

Static vs. dynamic data Dynamic data:

Collected at runtime Profiling results Variable access and use counts Temporal data Basis for evaluation Especially important for OOP languages

STEP Toolkit for extensible profiling. Encodes and compresses trace data

in a trace definition language.

JIL document(.xml)

STEP

Java class(.class)

EVolvetrace format

Profiling agent(JVMPI, Kaffe, SOOT)

event pipe

STEP as a source of JIL STEP as a source of profiling data. Visualizers becomes consumers at

the backend of the event pipe. STEP traces are read and converted

to JIL. JIMPLEX has full control over what

elements are included and in what format.

STEP elements in JIL As a source of runtime dynamic data:

field accesses method invocations object allocations

Separation of data from data

Static and dynamic data are generated as independent XML sources.

Trace results from different profiling runs can be swapped in and out.

Data sources can live on separate servers.

Merging XML data sources To visualize both static and dynamic

elements simultaneously, the data is merged into a single source.

XML can be merged on the fly using XSL.

Separation of data and interface

Interfaces are independent of data. Can be implemented using any

combination of languages or technologies.

One possible interface will be presented here…

JIMPLEX Web-based visualization interface

implemented using HTML and XSL. Uses JIL documents as data sources,

allowing them to exist remotely. Runs on any machine equipped with a

web browser. Portable across platforms and networks. Modular and extensible.

JIMPLEX interface

myclass.xml(JIL document)

(c)

(b)

(a)Server A: JIL document storage

web server

jimplex.xsl(XSL stylesheet)

Server B: JIMPLEX server

web server

JIMPLEX(web page)

Client 1: JIMPLEX

web client

JIMPLEX(web page)

Client n: JIMPLEX

web client

…

XML data

HTML data

XML/XSL transformation

Example Interface

JIMPLEX interface Let’s take a look at the interface…

Contributions JIL document format

DTD specifications

SOOT extensions JIL document output format

STEP extensions JIL document generating backend

JIMPLEX visualizer XSL stylesheets

Future Work: JIL Extract more runtime attributes from

STEP, such as temporal data. Use XML merging to support multiple

STEP streams, allowing multi-dimensional profiling.

Use XML differentiation to support program and trace comparison, allowing better evaluation of optimizations.

Future Work: UI Any updates to JIL should be reflected in

the UI (ie. multi-dimensional profiling). With the inclusion of more and more data,

an application-based interface would provide better performance.

Profiling and other dynamic data are more suited towards a graphical representation.

Links Java Intermediate Language (JIL):

http://www.sable.mcgill.ca/jil/ JIL papers, resources, and the JIMPLEX visualizer.

SOOT: http://www.sable.mcgill.ca/soot/ SOOT papers, documentation, and downloads.

STEP: http://www.sable.mcgill.ca/step/ STEP papers, more to come.