1 files changed, 235 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/gc/timings.go b/src/cmd/compile/internal/gc/timings.go
new file mode 100644
index 0000000..56b3899
--- /dev/null
+++ b/src/cmd/compile/internal/gc/timings.go
@@ -0,0 +1,235 @@
+// Copyright 2016 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 gc
+
+import (
+	"fmt"
+	"io"
+	"strings"
+	"time"
+)
+
+// Timings collects the execution times of labeled phases
+// which are added trough a sequence of Start/Stop calls.
+// Events may be associated with each phase via AddEvent.
+type Timings struct {
+	list   []timestamp
+	events map[int][]*event // lazily allocated
+}
+
+type timestamp struct {
+	time  time.Time
+	label string
+	start bool
+}
+
+type event struct {
+	size int64  // count or amount of data processed (allocations, data size, lines, funcs, ...)
+	unit string // unit of size measure (count, MB, lines, funcs, ...)
+}
+
+func (t *Timings) append(labels []string, start bool) {
+	t.list = append(t.list, timestamp{time.Now(), strings.Join(labels, ":"), start})
+}
+
+// Start marks the beginning of a new phase and implicitly stops the previous phase.
+// The phase name is the colon-separated concatenation of the labels.
+func (t *Timings) Start(labels ...string) {
+	t.append(labels, true)
+}
+
+// Stop marks the end of a phase and implicitly starts a new phase.
+// The labels are added to the labels of the ended phase.
+func (t *Timings) Stop(labels ...string) {
+	t.append(labels, false)
+}
+
+// AddEvent associates an event, i.e., a count, or an amount of data,
+// with the most recently started or stopped phase; or the very first
+// phase if Start or Stop hasn't been called yet. The unit specifies
+// the unit of measurement (e.g., MB, lines, no. of funcs, etc.).
+func (t *Timings) AddEvent(size int64, unit string) {
+	m := t.events
+	if m == nil {
+		m = make(map[int][]*event)
+		t.events = m
+	}
+	i := len(t.list)
+	if i > 0 {
+		i--
+	}
+	m[i] = append(m[i], &event{size, unit})
+}
+
+// Write prints the phase times to w.
+// The prefix is printed at the start of each line.
+func (t *Timings) Write(w io.Writer, prefix string) {
+	if len(t.list) > 0 {
+		var lines lines
+
+		// group of phases with shared non-empty label prefix
+		var group struct {
+			label string        // label prefix
+			tot   time.Duration // accumulated phase time
+			size  int           // number of phases collected in group
+		}
+
+		// accumulated time between Stop/Start timestamps
+		var unaccounted time.Duration
+
+		// process Start/Stop timestamps
+		pt := &t.list[0] // previous timestamp
+		tot := t.list[len(t.list)-1].time.Sub(pt.time)
+		for i := 1; i < len(t.list); i++ {
+			qt := &t.list[i] // current timestamp
+			dt := qt.time.Sub(pt.time)
+
+			var label string
+			var events []*event
+			if pt.start {
+				// previous phase started
+				label = pt.label
+				events = t.events[i-1]
+				if qt.start {
+					// start implicitly ended previous phase; nothing to do
+				} else {
+					// stop ended previous phase; append stop labels, if any
+					if qt.label != "" {
+						label += ":" + qt.label
+					}
+					// events associated with stop replace prior events
+					if e := t.events[i]; e != nil {
+						events = e
+					}
+				}
+			} else {
+				// previous phase stopped
+				if qt.start {
+					// between a stopped and started phase; unaccounted time
+					unaccounted += dt
+				} else {
+					// previous stop implicitly started current phase
+					label = qt.label
+					events = t.events[i]
+				}
+			}
+			if label != "" {
+				// add phase to existing group, or start a new group
+				l := commonPrefix(group.label, label)
+				if group.size == 1 && l != "" || group.size > 1 && l == group.label {
+					// add to existing group
+					group.label = l
+					group.tot += dt
+					group.size++
+				} else {
+					// start a new group
+					if group.size > 1 {
+						lines.add(prefix+group.label+"subtotal", 1, group.tot, tot, nil)
+					}
+					group.label = label
+					group.tot = dt
+					group.size = 1
+				}
+
+				// write phase
+				lines.add(prefix+label, 1, dt, tot, events)
+			}
+
+			pt = qt
+		}
+
+		if group.size > 1 {
+			lines.add(prefix+group.label+"subtotal", 1, group.tot, tot, nil)
+		}
+
+		if unaccounted != 0 {
+			lines.add(prefix+"unaccounted", 1, unaccounted, tot, nil)
+		}
+
+		lines.add(prefix+"total", 1, tot, tot, nil)
+
+		lines.write(w)
+	}
+}
+
+func commonPrefix(a, b string) string {
+	i := 0
+	for i < len(a) && i < len(b) && a[i] == b[i] {
+		i++
+	}
+	return a[:i]
+}
+
+type lines [][]string
+
+func (lines *lines) add(label string, n int, dt, tot time.Duration, events []*event) {
+	var line []string
+	add := func(format string, args ...interface{}) {
+		line = append(line, fmt.Sprintf(format, args...))
+	}
+
+	add("%s", label)
+	add("    %d", n)
+	add("    %d ns/op", dt)
+	add("    %.2f %%", float64(dt)/float64(tot)*100)
+
+	for _, e := range events {
+		add("    %d", e.size)
+		add(" %s", e.unit)
+		add("    %d", int64(float64(e.size)/dt.Seconds()+0.5))
+		add(" %s/s", e.unit)
+	}
+
+	*lines = append(*lines, line)
+}
+
+func (lines lines) write(w io.Writer) {
+	// determine column widths and contents
+	var widths []int
+	var number []bool
+	for _, line := range lines {
+		for i, col := range line {
+			if i < len(widths) {
+				if len(col) > widths[i] {
+					widths[i] = len(col)
+				}
+			} else {
+				widths = append(widths, len(col))
+				number = append(number, isnumber(col)) // first line determines column contents
+			}
+		}
+	}
+
+	// make column widths a multiple of align for more stable output
+	const align = 1 // set to a value > 1 to enable
+	if align > 1 {
+		for i, w := range widths {
+			w += align - 1
+			widths[i] = w - w%align
+		}
+	}
+
+	// print lines taking column widths and contents into account
+	for _, line := range lines {
+		for i, col := range line {
+			format := "%-*s"
+			if number[i] {
+				format = "%*s" // numbers are right-aligned
+			}
+			fmt.Fprintf(w, format, widths[i], col)
+		}
+		fmt.Fprintln(w)
+	}
+}
+
+func isnumber(s string) bool {
+	for _, ch := range s {
+		if ch <= ' ' {
+			continue // ignore leading whitespace
+		}
+		return '0' <= ch && ch <= '9' || ch == '.' || ch == '-' || ch == '+'
+	}
+	return false
+}