case 48:
				op = ssa.OpZeroExt32to64
			default:
				s.Fatalf("weird integer sign extension %v -> %v", ft, tt)
			}
		}
		return s.newValue1(op, tt, v)
	}

	if ft.IsComplex() && tt.IsComplex() {
		var op ssa.Op
		if ft.Size() == tt.Size() {
			switch ft.Size() {
			case 8:
				op = ssa.OpRound32F
			case 16:
				op = ssa.OpRound64F
			default: