module d.semantic.flow;

import d.semantic.semantic;

import d.ir.instruction;

import source.location;

struct FlowAnalyzer {
private:
	SemanticPass pass;
	alias pass this;

	Body fbody;

	import d.ir.symbol;
	uint[Variable] closure;
	uint nextClosureIndex;

public:
	this(SemanticPass pass, Function f) in {
		assert(f.fbody, "f does not have a body");
	} do {
		this.pass = pass;

		fbody = f.fbody;
		nextClosureIndex = f.hasContext;
		foreach (p; f.params) {
			if (p.storage == Storage.Capture) {
				assert(p !in closure);
				closure[p] = nextClosureIndex++;
			}
		}
	}

	uint[Variable] getClosure() {
		foreach (b; range(fbody)) {
			visit(b);
		}

		return closure;
	}

	void visit(BasicBlockRef b) {
		auto instructions = range(fbody, b);
		foreach (i; instructions) {
			if (i.op != OpCode.Alloca) {
				continue;
			}

			auto v = i.var;
			if (v.storage == Storage.Capture) {
				assert(v !in closure);
				closure[v] = nextClosureIndex++;
			}
		}
	}
}