Reduce overhead of AlignedAtomic types

AlignedAtomicUint64 is 15 bytes and it takes 16 bytes in structures.  On
32-bit systems, variables and structure fields is guaranteed to be
32-bit aligned and this means that we need only 12 bytes to find 8
contiguous bytes.

1 files changed, 35 insertions, 0 deletions

diff --git a/pkg/atomicbitops/aligned_test.go b/pkg/atomicbitops/aligned_test.go
new file mode 100644
index 000000000..e7123d2b8
--- /dev/null
+++ b/pkg/atomicbitops/aligned_test.go
@@ -0,0 +1,35 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package atomicbitops
+
+import (
+	"testing"
+)
+
+func TestAtomiciInt64(t *testing.T) {
+	v := struct {
+		v8  int8
+		v64 AlignedAtomicInt64
+	}{}
+	v.v64.Add(1)
+}
+
+func TestAtomicUint64(t *testing.T) {
+	v := struct {
+		v8  uint8
+		v64 AlignedAtomicUint64
+	}{}
+	v.v64.Add(1)
+}