libgo: update to Go 1.8 release candidate 1

    
    Compiler changes:
      * Change map assignment to use mapassign and assign value directly.
      * Change string iteration to use decoderune, faster for ASCII strings.
      * Change makeslice to take int, and use makeslice64 for larger values.
      * Add new noverflow field to hmap struct used for maps.
    
    Unresolved problems, to be fixed later:
      * Commented out test in go/types/sizes_test.go that doesn't compile.
      * Commented out reflect.TestStructOf test for padding after zero-sized field.
    
    Reviewed-on: https://go-review.googlesource.com/35231

gotools/:
	Updates for Go 1.8rc1.
	* Makefile.am (go_cmd_go_files): Add bug.go.
	(s-zdefaultcc): Write defaultPkgConfig.
	* Makefile.in: Rebuild.

From-SVN: r244456

1 files changed, 42 insertions, 0 deletions

diff --git a/libgo/go/runtime/trace/trace.go b/libgo/go/runtime/trace/trace.go
new file mode 100644
index 00000000000..7cbb8a6e82c
--- /dev/null
+++ b/libgo/go/runtime/trace/trace.go
@@ -0,0 +1,42 @@
+// Copyright 2015 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.
+
+// Go execution tracer.
+// The tracer captures a wide range of execution events like goroutine
+// creation/blocking/unblocking, syscall enter/exit/block, GC-related events,
+// changes of heap size, processor start/stop, etc and writes them to an io.Writer
+// in a compact form. A precise nanosecond-precision timestamp and a stack
+// trace is captured for most events. A trace can be analyzed later with
+// 'go tool trace' command.
+package trace
+
+import (
+	"io"
+	"runtime"
+)
+
+// Start enables tracing for the current program.
+// While tracing, the trace will be buffered and written to w.
+// Start returns an error if tracing is already enabled.
+func Start(w io.Writer) error {
+	if err := runtime.StartTrace(); err != nil {
+		return err
+	}
+	go func() {
+		for {
+			data := runtime.ReadTrace()
+			if data == nil {
+				break
+			}
+			w.Write(data)
+		}
+	}()
+	return nil
+}
+
+// Stop stops the current tracing, if any.
+// Stop only returns after all the writes for the trace have completed.
+func Stop() {
+	runtime.StopTrace()
+}