1// run
2
3// Copyright 2024 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
7package main
8
9import (
10	"fmt"
11)
12
13type someType []uint64
14
15func (s *someType) push(v uint64) {
16	*s = append(*s, v)
17}
18
19func (s *someType) problematicFn(x1Lo, x1Hi, x2Lo, x2Hi uint64) {
20	r1 := int32(int16(x1Lo>>0)) * int32(int16(x2Lo>>0))
21	g()
22	r3 := int32(int16(x1Lo>>32)) * int32(int16(x2Lo>>32))
23	r4 := int32(int16(x1Lo>>48)) * int32(int16(x2Lo>>48))
24	r5 := int32(int16(x1Hi>>0)) * int32(int16(x2Hi>>0))
25	r7 := int32(int16(x1Hi>>32)) * int32(int16(x2Hi>>32))
26	r8 := int32(int16(x1Hi>>48)) * int32(int16(x2Hi>>48))
27	s.push(uint64(uint32(r1)) | (uint64(uint32(r3+r4)) << 32))
28	s.push(uint64(uint32(r5)) | (uint64(uint32(r7+r8)) << 32))
29}
30
31//go:noinline
32func g() {
33}
34
35func main() {
36	s := &someType{}
37	s.problematicFn(0x1000100010001, 0x1000100010001, 0xffffffffffffffff, 0xffffffffffffffff)
38	for i := 0; i < 2; i++ {
39		if got, want := (*s)[i], uint64(0xfffffffeffffffff); got != want {
40			fmt.Printf("s[%d]=%x, want %x\n", i, got, want)
41		}
42	}
43}
44