Side-effects

[Helge Jensen <jensen@slog.dk>]

For my BTA, I will need a side-effects analysis for methods.

The requirements for the analysis is that it should output a set of 
locations read and written foreach method, preferably as a function of 
the points-to sets of it's arguments and staticly read "globals", but 
less precision is also acceptable.

The analysis in SideEffectAnalysis.java seems to be (after some 
code-reading and experimentation) unsuitable.

It does not return points-to sets as it's output, but rather RWSets, 
which are basically Sets of SootFields, which I cannot (possibly because 
of my limited knowledge of the points-to analysis and soot) relate to 
points-to-sets.

It also seems to be monovariant in the call-site functions arguments, 
"lub'ing" the side-effects of all invocations of the function.

For example, assigning it assigns the same RWSets to the readSet and 
writeSet of the lines:

		Object x1 = rwarg_rec(sft1);
		Object x2 = rwarg_rec(sft2);

In the attached test-program.

Any input on what direction to go in is welcome. Ultimatly, I guess I 
would have to implement a side-effect analysis myself, but this problem 
must have happened to others?

If the SideEffectAnalysis does provide the information I'm requesting, 
how would I get that information?

For example, from the information that calling warg(sft), an SFT.o field 
is writted to, how would i go about extracting the information on 
whether it was sft.o? would my only option be to regard all SFT.o fields 
as one location?


--
Helge

class SFT {
	private int x;
	SFT o;
	int getx() { return x; }
	void setx(int x) { this.x = x; }
}

class SFT2 extends SFT {
	private int y;
	int getx() { return y; }
	void setx(int x) { this.y = x; }
}

public class SideEffectTest {
	static Object none(SFT sft) // R: {}, W: {}
	{
		return null;
	};
	static Object rarg(SFT sft) // R: { sft.o }, W: {}
	{
		if (sft.o == null)
			sft = sft.o;
		if ( sft.getx() > 0 )
			sft = sft.o;
		return null;
	}
	static Object warg(SFT sft) // R: {}, W: { sft.o }
	{
		sft.o = new SFT();
		sft.setx(1);
		return null;
	}

	static Object rwarg_rec(SFT sft) // R: { sft.o }, W: { sft.o }
	{
		rarg(sft);
		warg(sft);
		return null;
	}
	
	public static void main(String[] args) {
		SFT sft1 = new SFT();
		if ( args.length <= 0 )
			sft1.o = null;
		else
			sft1.o = new SFT();
		SFT sft2 = new SFT2();
			
		Object x1 = rwarg_rec(sft1);
		Object x2 = rwarg_rec(sft2);
	}
}