Go has several packages supporting program analysis in the standard library. https://golang.org/pkg/go/types/#Info populates separate maps for Defs and Uses. Check out the source for how they walk the SSA and calculate def-use chains.

A more convenient interface to go program analysis is https://godoc.org/golang.org/x/tools/go/loader. See https://blog.cloudflare.com/building-the-simplest-go-static-... for a basic tutorial on using the module.