File size: 1,238 Bytes
e36aeda | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 | // Copyright 2025 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.
package test
import (
"internal/testenv"
"testing"
"unsafe"
)
// Stack allocation size for variable-sized allocations.
// Matches constant of the same name in ../walk/builtin.go:walkMakeSlice.
const maxStackSize = 32
//go:noinline
func genericUse[T any](s []T) {
// Doesn't escape s.
}
func TestStackAllocation(t *testing.T) {
testenv.SkipIfOptimizationOff(t)
type testCase struct {
f func(int)
elemSize uintptr
}
for _, tc := range []testCase{
{
f: func(n int) {
genericUse(make([]int, n))
},
elemSize: unsafe.Sizeof(int(0)),
},
{
f: func(n int) {
genericUse(make([]*byte, n))
},
elemSize: unsafe.Sizeof((*byte)(nil)),
},
{
f: func(n int) {
genericUse(make([]string, n))
},
elemSize: unsafe.Sizeof(""),
},
} {
max := maxStackSize / int(tc.elemSize)
if n := testing.AllocsPerRun(10, func() {
tc.f(max)
}); n != 0 {
t.Fatalf("unexpected allocation: %f", n)
}
if n := testing.AllocsPerRun(10, func() {
tc.f(max + 1)
}); n != 1 {
t.Fatalf("unexpected allocation: %f", n)
}
}
}
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