// t = type of sub-portion of v.
func clobberWalk(b *ssa.Block, v *ir.Name, offset int64, t *types.Type) {
	if !t.HasPointers() {
		return
	}
	switch t.Kind() {
	case types.TPTR,
		types.TUNSAFEPTR,
		types.TFUNC,
		types.TCHAN,
		types.TMAP:
		clobberPtr(b, v, offset)

	case types.TSTRING:
		// struct { byte *str; int len; }
		clobberPtr(b, v, offset)