Add internal nogo analysis & checkescape tool.

See tools/nogo/README.md.

The checkescape tool is able to perform recursive escape analysis, using the
actual generated binary to confirm the results produced by the compiler itself.

As an initial use case, this replaces the manual escape analysis tests used for
go_marshal, and validates that the CopyIn and CopyOut paths will not require
any allocation or stack splits.

Updates #2243

PiperOrigin-RevId: 307532986

2 files changed, 109 insertions, 0 deletions

diff --git a/tools/go_marshal/test/escape/BUILD b/tools/go_marshal/test/escape/BUILD
new file mode 100644
index 000000000..f74e6ffae
--- /dev/null
+++ b/tools/go_marshal/test/escape/BUILD
@@ -0,0 +1,14 @@
+load("//tools:defs.bzl", "go_library")
+
+licenses(["notice"])
+
+go_library(
+    name = "escape",
+    testonly = 1,
+    srcs = ["escape.go"],
+    deps = [
+        "//pkg/usermem",
+        "//tools/go_marshal/marshal",
+        "//tools/go_marshal/test",
+    ],
+)
diff --git a/tools/go_marshal/test/escape/escape.go b/tools/go_marshal/test/escape/escape.go
new file mode 100644
index 000000000..6a46ddbf8
--- /dev/null
+++ b/tools/go_marshal/test/escape/escape.go
@@ -0,0 +1,95 @@
+// 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.
+
+package escape
+
+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 (t *dummyTask) MarshalBytes(addr usermem.Addr, marshallable marshal.Marshallable) {
+	buf := t.CopyScratchBuffer(marshallable.SizeBytes())
+	marshallable.MarshalBytes(buf)
+	t.CopyOutBytes(addr, buf)
+}
+
+func (t *dummyTask) MarshalUnsafe(addr usermem.Addr, marshallable marshal.Marshallable) {
+	buf := t.CopyScratchBuffer(marshallable.SizeBytes())
+	marshallable.MarshalUnsafe(buf)
+	t.CopyOutBytes(addr, buf)
+}
+
+// +checkescape:all
+//go:nosplit
+func doCopyIn(t *dummyTask) {
+	var stat test.Stat
+	stat.CopyIn(t, usermem.Addr(0xf000ba12))
+}
+
+// +checkescape:all
+//go:nosplit
+func doCopyOut(t *dummyTask) {
+	var stat test.Stat
+	stat.CopyOut(t, usermem.Addr(0xf000ba12))
+}
+
+// +mustescape:builtin
+// +mustescape:stack
+func doMarshalBytesDirect(t *dummyTask) {
+	var stat test.Stat
+	buf := t.CopyScratchBuffer(stat.SizeBytes())
+	stat.MarshalBytes(buf)
+	t.CopyOutBytes(usermem.Addr(0xf000ba12), buf)
+}
+
+// +mustescape:builtin
+// +mustescape:stack
+func doMarshalUnsafeDirect(t *dummyTask) {
+	var stat test.Stat
+	buf := t.CopyScratchBuffer(stat.SizeBytes())
+	stat.MarshalUnsafe(buf)
+	t.CopyOutBytes(usermem.Addr(0xf000ba12), buf)
+}
+
+// +mustescape:local,heap
+// +mustescape:stack
+func doMarshalBytesViaMarshallable(t *dummyTask) {
+	var stat test.Stat
+	t.MarshalBytes(usermem.Addr(0xf000ba12), &stat)
+}
+
+// +mustescape:local,heap
+// +mustescape:stack
+func doMarshalUnsafeViaMarshallable(t *dummyTask) {
+	var stat test.Stat
+	t.MarshalUnsafe(usermem.Addr(0xf000ba12), &stat)
+}