| // run | |
| //go:build !wasm | |
| // Copyright 2021 The Go Authors. All rights reserved. | |
| // Use of this source code is governed by a BSD-style | |
| // license that can be found in the LICENSE file. | |
| // wasm is excluded because the compiler chatter about register abi pragma ends up | |
| // on stdout, and causes the expected output to not match. | |
| package main | |
| import ( | |
| "fmt" | |
| ) | |
| var sink int = 3 | |
| //go:registerparams | |
| //go:noinline | |
| func F(a, b, c, d, e, f *int) { | |
| G(f, e, d, c, b, a) | |
| sink += *a // *a == 6 after swapping in G | |
| } | |
| //go:registerparams | |
| //go:noinline | |
| func G(a, b, c, d, e, f *int) { | |
| var scratch [1000 * 100]int | |
| scratch[*a] = *f // scratch[6] = 1 | |
| fmt.Println(*a, *b, *c, *d, *e, *f) // Forces it to spill b | |
| sink = scratch[*b+1] // scratch[5+1] == 1 | |
| *f, *a = *a, *f | |
| *e, *b = *b, *e | |
| *d, *c = *c, *d | |
| } | |
| func main() { | |
| a, b, c, d, e, f := 1, 2, 3, 4, 5, 6 | |
| F(&a, &b, &c, &d, &e, &f) | |
| fmt.Println(a, b, c, d, e, f) | |
| fmt.Println(sink) | |
| } | |