// except for incoming in-register arguments.
// The output of LoweredGetClosurePtr is generally hardwired to the correct register.
// That register contains the closure pointer on closure entry.
func CheckLoweredGetClosurePtr(v *ssa.Value) {
	entry := v.Block.Func.Entry
	if entry != v.Block {
		base.Fatalf("in %s, badly placed LoweredGetClosurePtr: %v %v", v.Block.Func.Name, v.Block, v)
	}
	for _, w := range entry.Values {