func (t *funcTab) add(min, max core.Address, f *Func) {
	t.entries = append(t.entries, funcTabEntry{min: min, max: max, f: f})
}
func (t *funcTab) add(min, max core.Address, f *Func) {
	t.entries = append(t.entries, funcTabEntry{min: min, max: max, f: f})
}
// add records that PCs in the range [min,max) map to function f.