diff options
author | Andrei Vagin <avagin@google.com> | 2020-03-06 21:12:32 -0800 |
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committer | GitHub <noreply@github.com> | 2020-03-06 21:12:32 -0800 |
commit | bf87da89d3c43555fd57e8f1d7aed21b6da78de4 (patch) | |
tree | 744ba15a2f663d64d56bf1c70bdfe4096f6a1af9 /tools/go_marshal/test/escape.go | |
parent | 89957c6c87b5ad5c7bac68f93d9472388db57702 (diff) | |
parent | ddfc7239be94fa9711df877a66a9718aabff8b96 (diff) |
Merge branch 'master' into pr_lazy_fpsimd_2
Diffstat (limited to 'tools/go_marshal/test/escape.go')
-rw-r--r-- | tools/go_marshal/test/escape.go | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/tools/go_marshal/test/escape.go b/tools/go_marshal/test/escape.go new file mode 100644 index 000000000..184f05ea3 --- /dev/null +++ b/tools/go_marshal/test/escape.go @@ -0,0 +1,114 @@ +// Copyright 2020 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. + +// This binary provides a convienient target for analyzing how the go-marshal +// API causes its various arguments to escape to the heap. To use, build and +// observe the output from the go compiler's escape analysis: +// +// $ bazel build :escape +// ... +// escape.go:67:2: moved to heap: task +// escape.go:77:31: make([]byte, size) escapes to heap +// escape.go:87:31: make([]byte, size) escapes to heap +// escape.go:96:6: moved to heap: stat +// ... +// +// This is not an automated test, but simply a minimal binary for easy analysis. +package main + +import ( + "gvisor.dev/gvisor/pkg/usermem" + "gvisor.dev/gvisor/tools/go_marshal/marshal" + "gvisor.dev/gvisor/tools/go_marshal/test" +) + +// dummyTask implements marshal.Task. +type dummyTask struct { +} + +func (*dummyTask) CopyScratchBuffer(size int) []byte { + return make([]byte, size) +} + +func (*dummyTask) CopyOutBytes(addr usermem.Addr, b []byte) (int, error) { + return len(b), nil +} + +func (*dummyTask) CopyInBytes(addr usermem.Addr, b []byte) (int, error) { + return len(b), nil +} + +func (task *dummyTask) MarshalBytes(addr usermem.Addr, marshallable marshal.Marshallable) { + buf := task.CopyScratchBuffer(marshallable.SizeBytes()) + marshallable.MarshalBytes(buf) + task.CopyOutBytes(addr, buf) +} + +func (task *dummyTask) MarshalUnsafe(addr usermem.Addr, marshallable marshal.Marshallable) { + buf := task.CopyScratchBuffer(marshallable.SizeBytes()) + marshallable.MarshalUnsafe(buf) + task.CopyOutBytes(addr, buf) +} + +// Expected escapes: +// - task: passed to marshal.Marshallable.CopyOut as the marshal.Task interface. +func doCopyOut() { + task := dummyTask{} + var stat test.Stat + stat.CopyOut(&task, usermem.Addr(0xf000ba12)) +} + +// Expected escapes: +// - buf: make allocates on the heap. +func doMarshalBytesDirect() { + task := dummyTask{} + var stat test.Stat + buf := task.CopyScratchBuffer(stat.SizeBytes()) + stat.MarshalBytes(buf) + task.CopyOutBytes(usermem.Addr(0xf000ba12), buf) +} + +// Expected escapes: +// - buf: make allocates on the heap. +func doMarshalUnsafeDirect() { + task := dummyTask{} + var stat test.Stat + buf := task.CopyScratchBuffer(stat.SizeBytes()) + stat.MarshalUnsafe(buf) + task.CopyOutBytes(usermem.Addr(0xf000ba12), buf) +} + +// Expected escapes: +// - stat: passed to dummyTask.MarshalBytes as the marshal.Marshallable interface. +func doMarshalBytesViaMarshallable() { + task := dummyTask{} + var stat test.Stat + task.MarshalBytes(usermem.Addr(0xf000ba12), &stat) +} + +// Expected escapes: +// - stat: passed to dummyTask.MarshalUnsafe as the marshal.Marshallable interface. +func doMarshalUnsafeViaMarshallable() { + task := dummyTask{} + var stat test.Stat + task.MarshalUnsafe(usermem.Addr(0xf000ba12), &stat) +} + +func main() { + doCopyOut() + doMarshalBytesDirect() + doMarshalUnsafeDirect() + doMarshalBytesViaMarshallable() + doMarshalUnsafeViaMarshallable() +} |