ASM-DefUse
ASM powered by definitions/uses analysis
ASM-DefUse extends ASM analysis API with control- and data-flow algorithms for definition/uses analysis.
Requirements
- Java 6
Setup
If you're using Maven just add this new dependency:
<dependency>
<groupId>br.usp.each.saeg</groupId>
<artifactId>asm-defuse</artifactId>
<version>${asm-defuse.version}</version>
</dependency>Control-flow analysis
The following code exemplify how to use FlowAnalyzer class
MethodNode mn = ... // A regular MethodNode from ASM tree API
FlowAnalyzer<BasicValue> analyzer = new FlowAnalyzer<BasicValue>(new BasicInterpreter());
analyzer.analyze("package/ClassName", mn);
int[][] successors = analyzer.getSuccessors();
int[][] predecessors = analyzer.getPredecessors();
int[][] basicBlocks = analyzer.getBasicBlocks();
int[] leaders = analyzer.getLeaders();
for (int i = 0; i < mn.instructions.size(); i++) {
// successors[i] array contains the indexes of the successors of instruction i
System.out.println("Instruction " + i + " has " + successors[i].length + " successors");
// predecessors[i] array contains the indexes of the predecessors of instruction i
System.out.println("Instruction " + i + " has " + predecessors[i].length + " predecessors");
System.out.println("Instruction " + i + " belongs to basic block " + leaders[i]);
}
for (int i = 0; i < basicBlocks.length; i++) {
System.out.println("Basic block " + i + " contains " + basicBlocks[i].length + " instructions");
}Data-flow analysis
The following code exemplify how to use DefUseAnalyzer class
MethodNode mn = ... // A regular MethodNode from ASM tree API
DefUseAnalyzer analyzer = new DefUseAnalyzer();
analyzer.analyze("package/ClassName", mn);
Variable[] variables = analyzer.getVariables();
DefUseFrame[] frames = analyzer.getDefUseFrames();
System.out.println("This method contains " + variables.length + " variables");
for (int i = 0; i < mn.instructions.size(); i++) {
System.out.println("Instruction " + i + " contains definitions of " + frames[i].getDefinitions());
System.out.println("Instruction " + i + " contains usage of " + frames[i].getUses());
}Definition-Use Chain
The following code exemplify how to compute DefUseChain
MethodNode mn = ... // A regular MethodNode from ASM tree API
DefUseInterpreter interpreter = new DefUseInterpreter();
FlowAnalyzer<Value> flowAnalyzer = new FlowAnalyzer<Value>(interpreter);
DefUseAnalyzer analyzer = new DefUseAnalyzer(flowAnalyzer, interpreter);
analyzer.analyze("package/ClassName", mn);
Variable[] variables = analyzer.getVariables();
DefUseChain[] chains = new DepthFirstDefUseChainSearch().search(
analyzer.getDefUseFrames(),
analyzer.getVariables(),
flowAnalyzer.getSuccessors(),
flowAnalyzer.getPredecessors());
System.out.println("This method contains " + chains.length + " Definition-Use Chains");
for (int i = 0; i < chains.length; i++) {
DefUseChain chain = chains[i];
System.out.println("Instruction " + chain.def + " define variable " + variables[chain.var]);
System.out.println("Instruction " + chain.use + " uses variable " + variables[chain.var]);
// There is a path between chain.def and chain.use that not redefine chain.var
}