Add gops agent

vendor/github.com/google/gops/internal/obj/go.go

@@ -0,0 +1,86 @@
+// Copyright 2009 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 obj
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+// go-specific code shared across loaders (5l, 6l, 8l).
+
+var (
+	framepointer_enabled int
+	Fieldtrack_enabled   int
+)
+
+// Toolchain experiments.
+// These are controlled by the GOEXPERIMENT environment
+// variable recorded when the toolchain is built.
+// This list is also known to cmd/gc.
+var exper = []struct {
+	name string
+	val  *int
+}{
+	{"fieldtrack", &Fieldtrack_enabled},
+	{"framepointer", &framepointer_enabled},
+}
+
+func addexp(s string) {
+	// Could do general integer parsing here, but the runtime copy doesn't yet.
+	v := 1
+	name := s
+	if len(name) > 2 && name[:2] == "no" {
+		v = 0
+		name = name[2:]
+	}
+	for i := 0; i < len(exper); i++ {
+		if exper[i].name == name {
+			if exper[i].val != nil {
+				*exper[i].val = v
+			}
+			return
+		}
+	}
+
+	fmt.Printf("unknown experiment %s\n", s)
+	os.Exit(2)
+}
+
+func init() {
+	framepointer_enabled = 1 // default
+	for _, f := range strings.Split(goexperiment, ",") {
+		if f != "" {
+			addexp(f)
+		}
+	}
+}
+
+func Framepointer_enabled(goos, goarch string) bool {
+	return framepointer_enabled != 0 && goarch == "amd64" && goos != "nacl"
+}
+
+func Nopout(p *Prog) {
+	p.As = ANOP
+	p.Scond = 0
+	p.From = Addr{}
+	p.From3 = nil
+	p.Reg = 0
+	p.To = Addr{}
+}
+
+func Expstring() string {
+	buf := "X"
+	for i := range exper {
+		if *exper[i].val != 0 {
+			buf += "," + exper[i].name
+		}
+	}
+	if buf == "X" {
+		buf += ",none"
+	}
+	return "X:" + buf[2:]
+}