Golang cmd-compile-avail-gc.Flow类(方法)实例源码

func findu1(r *gc.Flow, v *obj.Addr) bool {
	for ; r != nil; r = r.S1 {
		if r.Active != 0 {
			return false
		}
		r.Active = 1
		switch copyu(r.Prog, v, nil) {
		case 1, /* used */
			2, /* read-alter-rewrite */
			4: /* set and used */
			return true

		case 3: /* set */
			return false
		}

		if r.S2 != nil {
			if findu1(r.S2, v) {
				return true
			}
		}
	}

	return false
}

// copy1 replaces uses of v2 with v1 starting at r and returns true if
// all uses were rewritten.
func copy1(v1 *obj.Addr, v2 *obj.Addr, r *gc.Flow, f int) bool {
	if uint32(r.Active) == gactive {
		return true
	}
	r.Active = int32(gactive)
	for ; r != nil; r = r.S1 {
		p := r.Prog
		if f == 0 && gc.Uniqp(r) == nil {
			// Multiple predecessors; conservatively
			// assume v1 was set on other path
			f = 1
		}
		t := copyu(p, v2, nil)
		switch t {
		case _ReadWriteSame:
			return false
		case _Write:
			return true
		case _Read, _ReadWriteDiff:
			if f != 0 {
				return false
			}
			if copyu(p, v2, v1) != 0 {
				return false
			}
			if t == _ReadWriteDiff {
				return true
			}
		}
		if f == 0 {
			switch copyu(p, v1, nil) {
			case _ReadWriteSame, _ReadWriteDiff, _Write:
				f = 1
			}
		}
		if r.S2 != nil {
			if !copy1(v1, v2, r.S2, f) {
				return false
			}
		}
	}
	return true
}