Print out callgraph of a specific entry point

[Mintyboi]

Allows us to generate / print out a callgraph for a specific entry point which we'd like to focus on.
Sample usage: wasm-opt foobar.wasm --print-call-graph -pa=callgraph-entry@foo > foo.dot

[kripken]

It looks like we don't have a test for this pass. If you want to extend it then I suggest we first land a PR that adds a test for the old functionality. Then this PR can land later, and the test will show nothing regressed.

[kripken]

As a convention we use the pass in the name of the flag (unless the flag applies to more than one pass somehow). See for example the --jspi pass which uses jspi-* names:

binaryen/src/passes/JSPI.cpp

Lines 88 to 97 in 6a42941

	auto stateChangingImports = String::trim(read_possible_response_file(
	options.getArgumentOrDefault("jspi-imports", "")));
	String::Split listedImports(stateChangingImports, ",");
	// Find which exports should create a promise.
	auto stateChangingExports = String::trim(read_possible_response_file(
	options.getArgumentOrDefault("jspi-exports", "")));
	String::Split listedExports(stateChangingExports, ",");
	bool wasmSplit = options.hasArgument("jspi-split-module");

[Mintyboi]

Resolved in 10f8643

[kripken]

Please expand in this comment, it is not obvious to me what "no filters" means.

Also please add a comment in the else.

[Mintyboi]

Added in 10f8643

[kripken]

Suggested change

	std::multimap<Name, Name> full_graph; // First param is the caller/parent, second is the callee/child
	std::multimap<Name, Name> fullGraph; // First param is the caller/parent, second is the callee/child

[Mintyboi]

Changed in 10f8643

[Mintyboi]

It looks like we don't have a test for this pass. If you want to extend it then I suggest we first land a PR that adds a test for the old functionality. Then this PR can land later, and the test will show nothing regressed.

I found it useful for my use case and was sharing in the case where others will be able to benefit from it as well. If there's not much traction on this, I'll probably leave it as is.
But I do agree with adding a tests for old functionality on it! I'll see if I can work on that.

[kripken]

If there's not much traction on this, I'll probably leave it as is.

I do think this can be useful! My comments weren't meant to discourage you, but just to explain how I think it best to proceed to get this landed.

It's probably also fine to add a test in this PR for both cases, as the pass is simple enough.

[kripken]

Please document this flag in the top comment (line 20 or so).