Parameter position from LocalPointerKey in the SSA IR.

[khatchad]

How do you obtain (consistently and uniformly) the parameter position of a LocalPointerKey representing a parameter? A LocalPointerKey consists of a value number and a CG node.

I see this code:

WALA/core/src/main/java/com/ibm/wala/ipa/callgraph/propagation/LocalPointerKey.java

Lines 62 to 64 in 89de874

	public final boolean isParameter() {
	return valueNumber <= node.getMethod().getNumberOfParameters();
	}

From this code, we see that there is some correspondence between value numbers and parameters. If isParameter() returns true, what can we say about the value number of the LocalPointerKey? Can we say that it is the $x-1$ th parameter?

[msridhar]

I believe that for instance methods, value number 1 is the receiver, and then the remaining parameters get consecutive value numbers after that. For static methods, value number 1 is the first declared formal parameter and they are numbered consecutively after that. Does that match what you are seeing?

[khatchad]

No, but I am looking at IR from Python CAst. There, at least for functions (not methods), value number 1 is actually the function itself. I believe that this is how @juliandolby is dealing with the import aliasing in Python.

[msridhar]

Ah, ok, I don't really know the scheme for Python. For JavaScript something similar happens, where value number 1 is the function itself. So I guess the real answer here is that the scheme may depend on the front-end language being used.

[khatchad]

Is this scheme documented anywhere? I had a quick look in the wiki but couldn't find anything.