_linters/src/honnef.co/go/tools/ssa/builder.go
func (b *builder) expr(fn *Function, e ast.Expr) Value {
	e = unparen(e)

	tv := fn.Pkg.info.Types[e]

	// Is expression a constant?
	if tv.Value != nil {
		return NewConst(tv.Value, tv.Type)
	}

	var v Value
	if tv.Addressable() {
		// Prefer pointer arithmetic ({Index,Field}Addr) followed
		// by Load over subelement extraction (e.g. Index, Field),
		// to avoid large copies.
		v = b.addr(fn, e, false).load(fn)
	} else {
		v = b.expr0(fn, e, tv)
	}
	if fn.debugInfo() {
		emitDebugRef(fn, e, v, false)
	}
	return v
}
func (b *builder) expr(fn *Function, e ast.Expr) Value {
	e = unparen(e)

	tv := fn.Pkg.info.Types[e]

	// Is expression a constant?
	if tv.Value != nil {
		return NewConst(tv.Value, tv.Type)
	}

	var v Value
	if tv.Addressable() {
		// Prefer pointer arithmetic ({Index,Field}Addr) followed
		// by Load over subelement extraction (e.g. Index, Field),
		// to avoid large copies.
		v = b.addr(fn, e, false).load(fn)
	} else {
		v = b.expr0(fn, e, tv)
	}
	if fn.debugInfo() {
		emitDebugRef(fn, e, v, false)
	}
	return v
}
// expr lowers a single-result expression e to SSA form, emitting code
// to fn and returning the Value defined by the expression.
//