public static boolean actionIsContextDependent(ActionAST actionAST) {
		ANTLRStringStream in = new ANTLRStringStream(actionAST.token.getText());
		in.setLine(actionAST.token.getLine());
		in.setCharPositionInLine(actionAST.token.getCharPositionInLine());
		final boolean[] dependent = new boolean[] {false}; // can't be simple bool with anon class
		ActionSplitterListener listener = new BlankActionSplitterListener() {
			@Override
			public void nonLocalAttr(String expr, Token x, Token y) { dependent[0] = true; }
			@Override
			public void qualifiedAttr(String expr, Token x, Token y) { dependent[0] = true; }
			@Override
			public void setAttr(String expr, Token x, Token rhs) { dependent[0] = true; }
			@Override
			public void setExprAttribute(String expr) { dependent[0] = true; }
			@Override
			public void setNonLocalAttr(String expr, Token x, Token y, Token rhs) { dependent[0] = true; }
			@Override
			public void attr(String expr, Token x) {  dependent[0] = true; }
		};
		ActionSplitter splitter = new ActionSplitter(in, listener);
		// forces eval, triggers listener methods
		splitter.getActionTokens();
		return dependent[0];
	}
Look for errors and deadcode stuff
tool/src/org/antlr/v4/semantics/UseDefAnalyzer.java