1// run
2
3// Copyright 2020 The Go Authors. All rights reserved.
4// Use of this source code is governed by a BSD-style
5// license that can be found in the LICENSE file.
6
7// Checks that conversion of CMP(x,-y) -> CMN(x,y) is only applied in correct context.
8
9package main
10
11type decimal struct {
12	d  [8]byte // digits, big-endian representation
13	dp int     // decimal point
14}
15
16var powtab = []int{1, 3, 6, 9, 13, 16, 19, 23, 26}
17
18//go:noinline
19func foo(d *decimal) int {
20	exp := int(d.d[1])
21	if d.dp < 0 || d.dp == 0 && d.d[0] < '5' {
22		var n int
23		if -d.dp >= len(powtab) {
24			n = 27
25		} else {
26			n = powtab[-d.dp] // incorrect CMP -> CMN substitution causes indexing panic.
27		}
28		exp += n
29	}
30	return exp
31}
32
33func main() {
34	var d decimal
35	d.d[0] = '1'
36	if foo(&d) != 1 {
37		println("FAILURE (though not the one this test was written to catch)")
38	}
39}
40