Imported Upstream version 1.4upstream/1.4

5 files changed, 1504 insertions, 0 deletions

diff --git a/src/debug/gosym/pclinetest.asm b/src/debug/gosym/pclinetest.asm
new file mode 100644
index 000000000..b9ee9c0a5
--- /dev/null
+++ b/src/debug/gosym/pclinetest.asm
@@ -0,0 +1,58 @@
+TEXT linefrompc(SB),4,$0	// Each byte stores its line delta
+BYTE $2;
+BYTE $1;
+BYTE $1; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1;
+BYTE $1;
+BYTE $1; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+BYTE $1; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+#include "pclinetest.h"
+BYTE $2;
+#include "pclinetest.h"
+BYTE $2;
+BYTE $255;
+
+TEXT pcfromline(SB),4,$0	// Each record stores its line delta, then n, then n more bytes
+BYTE $32; BYTE $0;
+BYTE $1; BYTE $1; BYTE $0;
+BYTE $1; BYTE $0;
+
+BYTE $2; BYTE $4; BYTE $0; BYTE $0; BYTE $0; BYTE $0;
+
+
+#include "pclinetest.h"
+BYTE $4; BYTE $0;
+
+
+BYTE $3; BYTE $3; BYTE $0; BYTE $0; BYTE $0;
+#include "pclinetest.h"
+
+
+BYTE $4; BYTE $3; BYTE $0; BYTE $0; BYTE $0;
+BYTE $255;
+
+// Keep the linker happy
+TEXT main·main(SB),4,$0
+	RET
+
+TEXT main·init(SB),4,$0
+	// Prevent GC of our test symbols
+	CALL linefrompc(SB)
+	CALL pcfromline(SB)
+	RET
diff --git a/src/debug/gosym/pclinetest.h b/src/debug/gosym/pclinetest.h
new file mode 100644
index 000000000..156c0b87b
--- /dev/null
+++ b/src/debug/gosym/pclinetest.h
@@ -0,0 +1,9 @@
+// +build ignore
+
+// Empty include file to generate z symbols
+
+
+
+
+
+// EOF
diff --git a/src/debug/gosym/pclntab.go b/src/debug/gosym/pclntab.go
new file mode 100644
index 000000000..6620aefb0
--- /dev/null
+++ b/src/debug/gosym/pclntab.go
@@ -0,0 +1,453 @@
+// 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.
+
+/*
+ * Line tables
+ */
+
+package gosym
+
+import (
+	"encoding/binary"
+	"sync"
+)
+
+// A LineTable is a data structure mapping program counters to line numbers.
+//
+// In Go 1.1 and earlier, each function (represented by a Func) had its own LineTable,
+// and the line number corresponded to a numbering of all source lines in the
+// program, across all files. That absolute line number would then have to be
+// converted separately to a file name and line number within the file.
+//
+// In Go 1.2, the format of the data changed so that there is a single LineTable
+// for the entire program, shared by all Funcs, and there are no absolute line
+// numbers, just line numbers within specific files.
+//
+// For the most part, LineTable's methods should be treated as an internal
+// detail of the package; callers should use the methods on Table instead.
+type LineTable struct {
+	Data []byte
+	PC   uint64
+	Line int
+
+	// Go 1.2 state
+	mu       sync.Mutex
+	go12     int // is this in Go 1.2 format? -1 no, 0 unknown, 1 yes
+	binary   binary.ByteOrder
+	quantum  uint32
+	ptrsize  uint32
+	functab  []byte
+	nfunctab uint32
+	filetab  []byte
+	nfiletab uint32
+	fileMap  map[string]uint32
+}
+
+// NOTE(rsc): This is wrong for GOARCH=arm, which uses a quantum of 4,
+// but we have no idea whether we're using arm or not. This only
+// matters in the old (pre-Go 1.2) symbol table format, so it's not worth
+// fixing.
+const oldQuantum = 1
+
+func (t *LineTable) parse(targetPC uint64, targetLine int) (b []byte, pc uint64, line int) {
+	// The PC/line table can be thought of as a sequence of
+	//  <pc update>* <line update>
+	// batches.  Each update batch results in a (pc, line) pair,
+	// where line applies to every PC from pc up to but not
+	// including the pc of the next pair.
+	//
+	// Here we process each update individually, which simplifies
+	// the code, but makes the corner cases more confusing.
+	b, pc, line = t.Data, t.PC, t.Line
+	for pc <= targetPC && line != targetLine && len(b) > 0 {
+		code := b[0]
+		b = b[1:]
+		switch {
+		case code == 0:
+			if len(b) < 4 {
+				b = b[0:0]
+				break
+			}
+			val := binary.BigEndian.Uint32(b)
+			b = b[4:]
+			line += int(val)
+		case code <= 64:
+			line += int(code)
+		case code <= 128:
+			line -= int(code - 64)
+		default:
+			pc += oldQuantum * uint64(code-128)
+			continue
+		}
+		pc += oldQuantum
+	}
+	return b, pc, line
+}
+
+func (t *LineTable) slice(pc uint64) *LineTable {
+	data, pc, line := t.parse(pc, -1)
+	return &LineTable{Data: data, PC: pc, Line: line}
+}
+
+// PCToLine returns the line number for the given program counter.
+// Callers should use Table's PCToLine method instead.
+func (t *LineTable) PCToLine(pc uint64) int {
+	if t.isGo12() {
+		return t.go12PCToLine(pc)
+	}
+	_, _, line := t.parse(pc, -1)
+	return line
+}
+
+// LineToPC returns the program counter for the given line number,
+// considering only program counters before maxpc.
+// Callers should use Table's LineToPC method instead.
+func (t *LineTable) LineToPC(line int, maxpc uint64) uint64 {
+	if t.isGo12() {
+		return 0
+	}
+	_, pc, line1 := t.parse(maxpc, line)
+	if line1 != line {
+		return 0
+	}
+	// Subtract quantum from PC to account for post-line increment
+	return pc - oldQuantum
+}
+
+// NewLineTable returns a new PC/line table
+// corresponding to the encoded data.
+// Text must be the start address of the
+// corresponding text segment.
+func NewLineTable(data []byte, text uint64) *LineTable {
+	return &LineTable{Data: data, PC: text, Line: 0}
+}
+
+// Go 1.2 symbol table format.
+// See golang.org/s/go12symtab.
+//
+// A general note about the methods here: rather than try to avoid
+// index out of bounds errors, we trust Go to detect them, and then
+// we recover from the panics and treat them as indicative of a malformed
+// or incomplete table.
+//
+// The methods called by symtab.go, which begin with "go12" prefixes,
+// are expected to have that recovery logic.
+
+// isGo12 reports whether this is a Go 1.2 (or later) symbol table.
+func (t *LineTable) isGo12() bool {
+	t.go12Init()
+	return t.go12 == 1
+}
+
+const go12magic = 0xfffffffb
+
+// uintptr returns the pointer-sized value encoded at b.
+// The pointer size is dictated by the table being read.
+func (t *LineTable) uintptr(b []byte) uint64 {
+	if t.ptrsize == 4 {
+		return uint64(t.binary.Uint32(b))
+	}
+	return t.binary.Uint64(b)
+}
+
+// go12init initializes the Go 1.2 metadata if t is a Go 1.2 symbol table.
+func (t *LineTable) go12Init() {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if t.go12 != 0 {
+		return
+	}
+
+	defer func() {
+		// If we panic parsing, assume it's not a Go 1.2 symbol table.
+		recover()
+	}()
+
+	// Check header: 4-byte magic, two zeros, pc quantum, pointer size.
+	t.go12 = -1 // not Go 1.2 until proven otherwise
+	if len(t.Data) < 16 || t.Data[4] != 0 || t.Data[5] != 0 ||
+		(t.Data[6] != 1 && t.Data[6] != 4) || // pc quantum
+		(t.Data[7] != 4 && t.Data[7] != 8) { // pointer size
+		return
+	}
+
+	switch uint32(go12magic) {
+	case binary.LittleEndian.Uint32(t.Data):
+		t.binary = binary.LittleEndian
+	case binary.BigEndian.Uint32(t.Data):
+		t.binary = binary.BigEndian
+	default:
+		return
+	}
+
+	t.quantum = uint32(t.Data[6])
+	t.ptrsize = uint32(t.Data[7])
+
+	t.nfunctab = uint32(t.uintptr(t.Data[8:]))
+	t.functab = t.Data[8+t.ptrsize:]
+	functabsize := t.nfunctab*2*t.ptrsize + t.ptrsize
+	fileoff := t.binary.Uint32(t.functab[functabsize:])
+	t.functab = t.functab[:functabsize]
+	t.filetab = t.Data[fileoff:]
+	t.nfiletab = t.binary.Uint32(t.filetab)
+	t.filetab = t.filetab[:t.nfiletab*4]
+
+	t.go12 = 1 // so far so good
+}
+
+// go12Funcs returns a slice of Funcs derived from the Go 1.2 pcln table.
+func (t *LineTable) go12Funcs() []Func {
+	// Assume it is malformed and return nil on error.
+	defer func() {
+		recover()
+	}()
+
+	n := len(t.functab) / int(t.ptrsize) / 2
+	funcs := make([]Func, n)
+	for i := range funcs {
+		f := &funcs[i]
+		f.Entry = uint64(t.uintptr(t.functab[2*i*int(t.ptrsize):]))
+		f.End = uint64(t.uintptr(t.functab[(2*i+2)*int(t.ptrsize):]))
+		info := t.Data[t.uintptr(t.functab[(2*i+1)*int(t.ptrsize):]):]
+		f.LineTable = t
+		f.FrameSize = int(t.binary.Uint32(info[t.ptrsize+2*4:]))
+		f.Sym = &Sym{
+			Value:  f.Entry,
+			Type:   'T',
+			Name:   t.string(t.binary.Uint32(info[t.ptrsize:])),
+			GoType: 0,
+			Func:   f,
+		}
+	}
+	return funcs
+}
+
+// findFunc returns the func corresponding to the given program counter.
+func (t *LineTable) findFunc(pc uint64) []byte {
+	if pc < t.uintptr(t.functab) || pc >= t.uintptr(t.functab[len(t.functab)-int(t.ptrsize):]) {
+		return nil
+	}
+
+	// The function table is a list of 2*nfunctab+1 uintptrs,
+	// alternating program counters and offsets to func structures.
+	f := t.functab
+	nf := t.nfunctab
+	for nf > 0 {
+		m := nf / 2
+		fm := f[2*t.ptrsize*m:]
+		if t.uintptr(fm) <= pc && pc < t.uintptr(fm[2*t.ptrsize:]) {
+			return t.Data[t.uintptr(fm[t.ptrsize:]):]
+		} else if pc < t.uintptr(fm) {
+			nf = m
+		} else {
+			f = f[(m+1)*2*t.ptrsize:]
+			nf -= m + 1
+		}
+	}
+	return nil
+}
+
+// readvarint reads, removes, and returns a varint from *pp.
+func (t *LineTable) readvarint(pp *[]byte) uint32 {
+	var v, shift uint32
+	p := *pp
+	for shift = 0; ; shift += 7 {
+		b := p[0]
+		p = p[1:]
+		v |= (uint32(b) & 0x7F) << shift
+		if b&0x80 == 0 {
+			break
+		}
+	}
+	*pp = p
+	return v
+}
+
+// string returns a Go string found at off.
+func (t *LineTable) string(off uint32) string {
+	for i := off; ; i++ {
+		if t.Data[i] == 0 {
+			return string(t.Data[off:i])
+		}
+	}
+}
+
+// step advances to the next pc, value pair in the encoded table.
+func (t *LineTable) step(p *[]byte, pc *uint64, val *int32, first bool) bool {
+	uvdelta := t.readvarint(p)
+	if uvdelta == 0 && !first {
+		return false
+	}
+	if uvdelta&1 != 0 {
+		uvdelta = ^(uvdelta >> 1)
+	} else {
+		uvdelta >>= 1
+	}
+	vdelta := int32(uvdelta)
+	pcdelta := t.readvarint(p) * t.quantum
+	*pc += uint64(pcdelta)
+	*val += vdelta
+	return true
+}
+
+// pcvalue reports the value associated with the target pc.
+// off is the offset to the beginning of the pc-value table,
+// and entry is the start PC for the corresponding function.
+func (t *LineTable) pcvalue(off uint32, entry, targetpc uint64) int32 {
+	if off == 0 {
+		return -1
+	}
+	p := t.Data[off:]
+
+	val := int32(-1)
+	pc := entry
+	for t.step(&p, &pc, &val, pc == entry) {
+		if targetpc < pc {
+			return val
+		}
+	}
+	return -1
+}
+
+// findFileLine scans one function in the binary looking for a
+// program counter in the given file on the given line.
+// It does so by running the pc-value tables mapping program counter
+// to file number. Since most functions come from a single file, these
+// are usually short and quick to scan. If a file match is found, then the
+// code goes to the expense of looking for a simultaneous line number match.
+func (t *LineTable) findFileLine(entry uint64, filetab, linetab uint32, filenum, line int32) uint64 {
+	if filetab == 0 || linetab == 0 {
+		return 0
+	}
+
+	fp := t.Data[filetab:]
+	fl := t.Data[linetab:]
+	fileVal := int32(-1)
+	filePC := entry
+	lineVal := int32(-1)
+	linePC := entry
+	fileStartPC := filePC
+	for t.step(&fp, &filePC, &fileVal, filePC == entry) {
+		if fileVal == filenum && fileStartPC < filePC {
+			// fileVal is in effect starting at fileStartPC up to
+			// but not including filePC, and it's the file we want.
+			// Run the PC table looking for a matching line number
+			// or until we reach filePC.
+			lineStartPC := linePC
+			for linePC < filePC && t.step(&fl, &linePC, &lineVal, linePC == entry) {
+				// lineVal is in effect until linePC, and lineStartPC < filePC.
+				if lineVal == line {
+					if fileStartPC <= lineStartPC {
+						return lineStartPC
+					}
+					if fileStartPC < linePC {
+						return fileStartPC
+					}
+				}
+				lineStartPC = linePC
+			}
+		}
+		fileStartPC = filePC
+	}
+	return 0
+}
+
+// go12PCToLine maps program counter to line number for the Go 1.2 pcln table.
+func (t *LineTable) go12PCToLine(pc uint64) (line int) {
+	defer func() {
+		if recover() != nil {
+			line = -1
+		}
+	}()
+
+	f := t.findFunc(pc)
+	if f == nil {
+		return -1
+	}
+	entry := t.uintptr(f)
+	linetab := t.binary.Uint32(f[t.ptrsize+5*4:])
+	return int(t.pcvalue(linetab, entry, pc))
+}
+
+// go12PCToFile maps program counter to file name for the Go 1.2 pcln table.
+func (t *LineTable) go12PCToFile(pc uint64) (file string) {
+	defer func() {
+		if recover() != nil {
+			file = ""
+		}
+	}()
+
+	f := t.findFunc(pc)
+	if f == nil {
+		return ""
+	}
+	entry := t.uintptr(f)
+	filetab := t.binary.Uint32(f[t.ptrsize+4*4:])
+	fno := t.pcvalue(filetab, entry, pc)
+	if fno <= 0 {
+		return ""
+	}
+	return t.string(t.binary.Uint32(t.filetab[4*fno:]))
+}
+
+// go12LineToPC maps a (file, line) pair to a program counter for the Go 1.2 pcln table.
+func (t *LineTable) go12LineToPC(file string, line int) (pc uint64) {
+	defer func() {
+		if recover() != nil {
+			pc = 0
+		}
+	}()
+
+	t.initFileMap()
+	filenum := t.fileMap[file]
+	if filenum == 0 {
+		return 0
+	}
+
+	// Scan all functions.
+	// If this turns out to be a bottleneck, we could build a map[int32][]int32
+	// mapping file number to a list of functions with code from that file.
+	for i := uint32(0); i < t.nfunctab; i++ {
+		f := t.Data[t.uintptr(t.functab[2*t.ptrsize*i+t.ptrsize:]):]
+		entry := t.uintptr(f)
+		filetab := t.binary.Uint32(f[t.ptrsize+4*4:])
+		linetab := t.binary.Uint32(f[t.ptrsize+5*4:])
+		pc := t.findFileLine(entry, filetab, linetab, int32(filenum), int32(line))
+		if pc != 0 {
+			return pc
+		}
+	}
+	return 0
+}
+
+// initFileMap initializes the map from file name to file number.
+func (t *LineTable) initFileMap() {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+
+	if t.fileMap != nil {
+		return
+	}
+	m := make(map[string]uint32)
+
+	for i := uint32(1); i < t.nfiletab; i++ {
+		s := t.string(t.binary.Uint32(t.filetab[4*i:]))
+		m[s] = i
+	}
+	t.fileMap = m
+}
+
+// go12MapFiles adds to m a key for every file in the Go 1.2 LineTable.
+// Every key maps to obj. That's not a very interesting map, but it provides
+// a way for callers to obtain the list of files in the program.
+func (t *LineTable) go12MapFiles(m map[string]*Obj, obj *Obj) {
+	defer func() {
+		recover()
+	}()
+
+	t.initFileMap()
+	for file := range t.fileMap {
+		m[file] = obj
+	}
+}
diff --git a/src/debug/gosym/pclntab_test.go b/src/debug/gosym/pclntab_test.go
new file mode 100644
index 000000000..35502e8c3
--- /dev/null
+++ b/src/debug/gosym/pclntab_test.go
@@ -0,0 +1,274 @@
+// 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 gosym
+
+import (
+	"debug/elf"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"testing"
+)
+
+var (
+	pclineTempDir    string
+	pclinetestBinary string
+)
+
+func dotest(self bool) bool {
+	// For now, only works on amd64 platforms.
+	if runtime.GOARCH != "amd64" {
+		return false
+	}
+	// Self test reads test binary; only works on Linux.
+	if self && runtime.GOOS != "linux" {
+		return false
+	}
+	// Command below expects "sh", so Unix.
+	if runtime.GOOS == "windows" || runtime.GOOS == "plan9" {
+		return false
+	}
+	if pclinetestBinary != "" {
+		return true
+	}
+	var err error
+	pclineTempDir, err = ioutil.TempDir("", "pclinetest")
+	if err != nil {
+		panic(err)
+	}
+	if strings.Contains(pclineTempDir, " ") {
+		panic("unexpected space in tempdir")
+	}
+	// This command builds pclinetest from pclinetest.asm;
+	// the resulting binary looks like it was built from pclinetest.s,
+	// but we have renamed it to keep it away from the go tool.
+	pclinetestBinary = filepath.Join(pclineTempDir, "pclinetest")
+	command := fmt.Sprintf("go tool 6a -o %s.6 pclinetest.asm && go tool 6l -H linux -E main -o %s %s.6",
+		pclinetestBinary, pclinetestBinary, pclinetestBinary)
+	cmd := exec.Command("sh", "-c", command)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	if err := cmd.Run(); err != nil {
+		panic(err)
+	}
+	return true
+}
+
+func endtest() {
+	if pclineTempDir != "" {
+		os.RemoveAll(pclineTempDir)
+		pclineTempDir = ""
+		pclinetestBinary = ""
+	}
+}
+
+func getTable(t *testing.T) *Table {
+	f, tab := crack(os.Args[0], t)
+	f.Close()
+	return tab
+}
+
+func crack(file string, t *testing.T) (*elf.File, *Table) {
+	// Open self
+	f, err := elf.Open(file)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return parse(file, f, t)
+}
+
+func parse(file string, f *elf.File, t *testing.T) (*elf.File, *Table) {
+	symdat, err := f.Section(".gosymtab").Data()
+	if err != nil {
+		f.Close()
+		t.Fatalf("reading %s gosymtab: %v", file, err)
+	}
+	pclndat, err := f.Section(".gopclntab").Data()
+	if err != nil {
+		f.Close()
+		t.Fatalf("reading %s gopclntab: %v", file, err)
+	}
+
+	pcln := NewLineTable(pclndat, f.Section(".text").Addr)
+	tab, err := NewTable(symdat, pcln)
+	if err != nil {
+		f.Close()
+		t.Fatalf("parsing %s gosymtab: %v", file, err)
+	}
+
+	return f, tab
+}
+
+var goarch = os.Getenv("O")
+
+func TestLineFromAline(t *testing.T) {
+	if !dotest(true) {
+		return
+	}
+	defer endtest()
+
+	tab := getTable(t)
+	if tab.go12line != nil {
+		// aline's don't exist in the Go 1.2 table.
+		t.Skip("not relevant to Go 1.2 symbol table")
+	}
+
+	// Find the sym package
+	pkg := tab.LookupFunc("debug/gosym.TestLineFromAline").Obj
+	if pkg == nil {
+		t.Fatalf("nil pkg")
+	}
+
+	// Walk every absolute line and ensure that we hit every
+	// source line monotonically
+	lastline := make(map[string]int)
+	final := -1
+	for i := 0; i < 10000; i++ {
+		path, line := pkg.lineFromAline(i)
+		// Check for end of object
+		if path == "" {
+			if final == -1 {
+				final = i - 1
+			}
+			continue
+		} else if final != -1 {
+			t.Fatalf("reached end of package at absolute line %d, but absolute line %d mapped to %s:%d", final, i, path, line)
+		}
+		// It's okay to see files multiple times (e.g., sys.a)
+		if line == 1 {
+			lastline[path] = 1
+			continue
+		}
+		// Check that the is the next line in path
+		ll, ok := lastline[path]
+		if !ok {
+			t.Errorf("file %s starts on line %d", path, line)
+		} else if line != ll+1 {
+			t.Fatalf("expected next line of file %s to be %d, got %d", path, ll+1, line)
+		}
+		lastline[path] = line
+	}
+	if final == -1 {
+		t.Errorf("never reached end of object")
+	}
+}
+
+func TestLineAline(t *testing.T) {
+	if !dotest(true) {
+		return
+	}
+	defer endtest()
+
+	tab := getTable(t)
+	if tab.go12line != nil {
+		// aline's don't exist in the Go 1.2 table.
+		t.Skip("not relevant to Go 1.2 symbol table")
+	}
+
+	for _, o := range tab.Files {
+		// A source file can appear multiple times in a
+		// object.  alineFromLine will always return alines in
+		// the first file, so track which lines we've seen.
+		found := make(map[string]int)
+		for i := 0; i < 1000; i++ {
+			path, line := o.lineFromAline(i)
+			if path == "" {
+				break
+			}
+
+			// cgo files are full of 'Z' symbols, which we don't handle
+			if len(path) > 4 && path[len(path)-4:] == ".cgo" {
+				continue
+			}
+
+			if minline, ok := found[path]; path != "" && ok {
+				if minline >= line {
+					// We've already covered this file
+					continue
+				}
+			}
+			found[path] = line
+
+			a, err := o.alineFromLine(path, line)
+			if err != nil {
+				t.Errorf("absolute line %d in object %s maps to %s:%d, but mapping that back gives error %s", i, o.Paths[0].Name, path, line, err)
+			} else if a != i {
+				t.Errorf("absolute line %d in object %s maps to %s:%d, which maps back to absolute line %d\n", i, o.Paths[0].Name, path, line, a)
+			}
+		}
+	}
+}
+
+func TestPCLine(t *testing.T) {
+	if !dotest(false) {
+		return
+	}
+	defer endtest()
+
+	f, tab := crack(pclinetestBinary, t)
+	text := f.Section(".text")
+	textdat, err := text.Data()
+	if err != nil {
+		t.Fatalf("reading .text: %v", err)
+	}
+
+	// Test PCToLine
+	sym := tab.LookupFunc("linefrompc")
+	wantLine := 0
+	for pc := sym.Entry; pc < sym.End; pc++ {
+		off := pc - text.Addr // TODO(rsc): should not need off; bug in 8g
+		if textdat[off] == 255 {
+			break
+		}
+		wantLine += int(textdat[off])
+		t.Logf("off is %d %#x (max %d)", off, textdat[off], sym.End-pc)
+		file, line, fn := tab.PCToLine(pc)
+		if fn == nil {
+			t.Errorf("failed to get line of PC %#x", pc)
+		} else if !strings.HasSuffix(file, "pclinetest.asm") || line != wantLine || fn != sym {
+			t.Errorf("PCToLine(%#x) = %s:%d (%s), want %s:%d (%s)", pc, file, line, fn.Name, "pclinetest.asm", wantLine, sym.Name)
+		}
+	}
+
+	// Test LineToPC
+	sym = tab.LookupFunc("pcfromline")
+	lookupline := -1
+	wantLine = 0
+	off := uint64(0) // TODO(rsc): should not need off; bug in 8g
+	for pc := sym.Value; pc < sym.End; pc += 2 + uint64(textdat[off]) {
+		file, line, fn := tab.PCToLine(pc)
+		off = pc - text.Addr
+		if textdat[off] == 255 {
+			break
+		}
+		wantLine += int(textdat[off])
+		if line != wantLine {
+			t.Errorf("expected line %d at PC %#x in pcfromline, got %d", wantLine, pc, line)
+			off = pc + 1 - text.Addr
+			continue
+		}
+		if lookupline == -1 {
+			lookupline = line
+		}
+		for ; lookupline <= line; lookupline++ {
+			pc2, fn2, err := tab.LineToPC(file, lookupline)
+			if lookupline != line {
+				// Should be nothing on this line
+				if err == nil {
+					t.Errorf("expected no PC at line %d, got %#x (%s)", lookupline, pc2, fn2.Name)
+				}
+			} else if err != nil {
+				t.Errorf("failed to get PC of line %d: %s", lookupline, err)
+			} else if pc != pc2 {
+				t.Errorf("expected PC %#x (%s) at line %d, got PC %#x (%s)", pc, fn.Name, line, pc2, fn2.Name)
+			}
+		}
+		off = pc + 1 - text.Addr
+	}
+}
diff --git a/src/debug/gosym/symtab.go b/src/debug/gosym/symtab.go
new file mode 100644
index 000000000..ee18499d1
--- /dev/null
+++ b/src/debug/gosym/symtab.go
@@ -0,0 +1,710 @@
+// 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 gosym implements access to the Go symbol
+// and line number tables embedded in Go binaries generated
+// by the gc compilers.
+package gosym
+
+// The table format is a variant of the format used in Plan 9's a.out
+// format, documented at http://plan9.bell-labs.com/magic/man2html/6/a.out.
+// The best reference for the differences between the Plan 9 format
+// and the Go format is the runtime source, specifically ../../runtime/symtab.c.
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"strconv"
+	"strings"
+)
+
+/*
+ * Symbols
+ */
+
+// A Sym represents a single symbol table entry.
+type Sym struct {
+	Value  uint64
+	Type   byte
+	Name   string
+	GoType uint64
+	// If this symbol if a function symbol, the corresponding Func
+	Func *Func
+}
+
+// Static reports whether this symbol is static (not visible outside its file).
+func (s *Sym) Static() bool { return s.Type >= 'a' }
+
+// PackageName returns the package part of the symbol name,
+// or the empty string if there is none.
+func (s *Sym) PackageName() string {
+	if i := strings.Index(s.Name, "."); i != -1 {
+		return s.Name[0:i]
+	}
+	return ""
+}
+
+// ReceiverName returns the receiver type name of this symbol,
+// or the empty string if there is none.
+func (s *Sym) ReceiverName() string {
+	l := strings.Index(s.Name, ".")
+	r := strings.LastIndex(s.Name, ".")
+	if l == -1 || r == -1 || l == r {
+		return ""
+	}
+	return s.Name[l+1 : r]
+}
+
+// BaseName returns the symbol name without the package or receiver name.
+func (s *Sym) BaseName() string {
+	if i := strings.LastIndex(s.Name, "."); i != -1 {
+		return s.Name[i+1:]
+	}
+	return s.Name
+}
+
+// A Func collects information about a single function.
+type Func struct {
+	Entry uint64
+	*Sym
+	End       uint64
+	Params    []*Sym
+	Locals    []*Sym
+	FrameSize int
+	LineTable *LineTable
+	Obj       *Obj
+}
+
+// An Obj represents a collection of functions in a symbol table.
+//
+// The exact method of division of a binary into separate Objs is an internal detail
+// of the symbol table format.
+//
+// In early versions of Go each source file became a different Obj.
+//
+// In Go 1 and Go 1.1, each package produced one Obj for all Go sources
+// and one Obj per C source file.
+//
+// In Go 1.2, there is a single Obj for the entire program.
+type Obj struct {
+	// Funcs is a list of functions in the Obj.
+	Funcs []Func
+
+	// In Go 1.1 and earlier, Paths is a list of symbols corresponding
+	// to the source file names that produced the Obj.
+	// In Go 1.2, Paths is nil.
+	// Use the keys of Table.Files to obtain a list of source files.
+	Paths []Sym // meta
+}
+
+/*
+ * Symbol tables
+ */
+
+// Table represents a Go symbol table.  It stores all of the
+// symbols decoded from the program and provides methods to translate
+// between symbols, names, and addresses.
+type Table struct {
+	Syms  []Sym
+	Funcs []Func
+	Files map[string]*Obj // nil for Go 1.2 and later binaries
+	Objs  []Obj           // nil for Go 1.2 and later binaries
+
+	go12line *LineTable // Go 1.2 line number table
+}
+
+type sym struct {
+	value  uint64
+	gotype uint64
+	typ    byte
+	name   []byte
+}
+
+var (
+	littleEndianSymtab    = []byte{0xFD, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00}
+	bigEndianSymtab       = []byte{0xFF, 0xFF, 0xFF, 0xFD, 0x00, 0x00, 0x00}
+	oldLittleEndianSymtab = []byte{0xFE, 0xFF, 0xFF, 0xFF, 0x00, 0x00}
+)
+
+func walksymtab(data []byte, fn func(sym) error) error {
+	if len(data) == 0 { // missing symtab is okay
+		return nil
+	}
+	var order binary.ByteOrder = binary.BigEndian
+	newTable := false
+	switch {
+	case bytes.HasPrefix(data, oldLittleEndianSymtab):
+		// Same as Go 1.0, but little endian.
+		// Format was used during interim development between Go 1.0 and Go 1.1.
+		// Should not be widespread, but easy to support.
+		data = data[6:]
+		order = binary.LittleEndian
+	case bytes.HasPrefix(data, bigEndianSymtab):
+		newTable = true
+	case bytes.HasPrefix(data, littleEndianSymtab):
+		newTable = true
+		order = binary.LittleEndian
+	}
+	var ptrsz int
+	if newTable {
+		if len(data) < 8 {
+			return &DecodingError{len(data), "unexpected EOF", nil}
+		}
+		ptrsz = int(data[7])
+		if ptrsz != 4 && ptrsz != 8 {
+			return &DecodingError{7, "invalid pointer size", ptrsz}
+		}
+		data = data[8:]
+	}
+	var s sym
+	p := data
+	for len(p) >= 4 {
+		var typ byte
+		if newTable {
+			// Symbol type, value, Go type.
+			typ = p[0] & 0x3F
+			wideValue := p[0]&0x40 != 0
+			goType := p[0]&0x80 != 0
+			if typ < 26 {
+				typ += 'A'
+			} else {
+				typ += 'a' - 26
+			}
+			s.typ = typ
+			p = p[1:]
+			if wideValue {
+				if len(p) < ptrsz {
+					return &DecodingError{len(data), "unexpected EOF", nil}
+				}
+				// fixed-width value
+				if ptrsz == 8 {
+					s.value = order.Uint64(p[0:8])
+					p = p[8:]
+				} else {
+					s.value = uint64(order.Uint32(p[0:4]))
+					p = p[4:]
+				}
+			} else {
+				// varint value
+				s.value = 0
+				shift := uint(0)
+				for len(p) > 0 && p[0]&0x80 != 0 {
+					s.value |= uint64(p[0]&0x7F) << shift
+					shift += 7
+					p = p[1:]
+				}
+				if len(p) == 0 {
+					return &DecodingError{len(data), "unexpected EOF", nil}
+				}
+				s.value |= uint64(p[0]) << shift
+				p = p[1:]
+			}
+			if goType {
+				if len(p) < ptrsz {
+					return &DecodingError{len(data), "unexpected EOF", nil}
+				}
+				// fixed-width go type
+				if ptrsz == 8 {
+					s.gotype = order.Uint64(p[0:8])
+					p = p[8:]
+				} else {
+					s.gotype = uint64(order.Uint32(p[0:4]))
+					p = p[4:]
+				}
+			}
+		} else {
+			// Value, symbol type.
+			s.value = uint64(order.Uint32(p[0:4]))
+			if len(p) < 5 {
+				return &DecodingError{len(data), "unexpected EOF", nil}
+			}
+			typ = p[4]
+			if typ&0x80 == 0 {
+				return &DecodingError{len(data) - len(p) + 4, "bad symbol type", typ}
+			}
+			typ &^= 0x80
+			s.typ = typ
+			p = p[5:]
+		}
+
+		// Name.
+		var i int
+		var nnul int
+		for i = 0; i < len(p); i++ {
+			if p[i] == 0 {
+				nnul = 1
+				break
+			}
+		}
+		switch typ {
+		case 'z', 'Z':
+			p = p[i+nnul:]
+			for i = 0; i+2 <= len(p); i += 2 {
+				if p[i] == 0 && p[i+1] == 0 {
+					nnul = 2
+					break
+				}
+			}
+		}
+		if len(p) < i+nnul {
+			return &DecodingError{len(data), "unexpected EOF", nil}
+		}
+		s.name = p[0:i]
+		i += nnul
+		p = p[i:]
+
+		if !newTable {
+			if len(p) < 4 {
+				return &DecodingError{len(data), "unexpected EOF", nil}
+			}
+			// Go type.
+			s.gotype = uint64(order.Uint32(p[:4]))
+			p = p[4:]
+		}
+		fn(s)
+	}
+	return nil
+}
+
+// NewTable decodes the Go symbol table in data,
+// returning an in-memory representation.
+func NewTable(symtab []byte, pcln *LineTable) (*Table, error) {
+	var n int
+	err := walksymtab(symtab, func(s sym) error {
+		n++
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	var t Table
+	if pcln.isGo12() {
+		t.go12line = pcln
+	}
+	fname := make(map[uint16]string)
+	t.Syms = make([]Sym, 0, n)
+	nf := 0
+	nz := 0
+	lasttyp := uint8(0)
+	err = walksymtab(symtab, func(s sym) error {
+		n := len(t.Syms)
+		t.Syms = t.Syms[0 : n+1]
+		ts := &t.Syms[n]
+		ts.Type = s.typ
+		ts.Value = uint64(s.value)
+		ts.GoType = uint64(s.gotype)
+		switch s.typ {
+		default:
+			// rewrite name to use . instead of · (c2 b7)
+			w := 0
+			b := s.name
+			for i := 0; i < len(b); i++ {
+				if b[i] == 0xc2 && i+1 < len(b) && b[i+1] == 0xb7 {
+					i++
+					b[i] = '.'
+				}
+				b[w] = b[i]
+				w++
+			}
+			ts.Name = string(s.name[0:w])
+		case 'z', 'Z':
+			if lasttyp != 'z' && lasttyp != 'Z' {
+				nz++
+			}
+			for i := 0; i < len(s.name); i += 2 {
+				eltIdx := binary.BigEndian.Uint16(s.name[i : i+2])
+				elt, ok := fname[eltIdx]
+				if !ok {
+					return &DecodingError{-1, "bad filename code", eltIdx}
+				}
+				if n := len(ts.Name); n > 0 && ts.Name[n-1] != '/' {
+					ts.Name += "/"
+				}
+				ts.Name += elt
+			}
+		}
+		switch s.typ {
+		case 'T', 't', 'L', 'l':
+			nf++
+		case 'f':
+			fname[uint16(s.value)] = ts.Name
+		}
+		lasttyp = s.typ
+		return nil
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	t.Funcs = make([]Func, 0, nf)
+	t.Files = make(map[string]*Obj)
+
+	var obj *Obj
+	if t.go12line != nil {
+		// Put all functions into one Obj.
+		t.Objs = make([]Obj, 1)
+		obj = &t.Objs[0]
+		t.go12line.go12MapFiles(t.Files, obj)
+	} else {
+		t.Objs = make([]Obj, 0, nz)
+	}
+
+	// Count text symbols and attach frame sizes, parameters, and
+	// locals to them.  Also, find object file boundaries.
+	lastf := 0
+	for i := 0; i < len(t.Syms); i++ {
+		sym := &t.Syms[i]
+		switch sym.Type {
+		case 'Z', 'z': // path symbol
+			if t.go12line != nil {
+				// Go 1.2 binaries have the file information elsewhere. Ignore.
+				break
+			}
+			// Finish the current object
+			if obj != nil {
+				obj.Funcs = t.Funcs[lastf:]
+			}
+			lastf = len(t.Funcs)
+
+			// Start new object
+			n := len(t.Objs)
+			t.Objs = t.Objs[0 : n+1]
+			obj = &t.Objs[n]
+
+			// Count & copy path symbols
+			var end int
+			for end = i + 1; end < len(t.Syms); end++ {
+				if c := t.Syms[end].Type; c != 'Z' && c != 'z' {
+					break
+				}
+			}
+			obj.Paths = t.Syms[i:end]
+			i = end - 1 // loop will i++
+
+			// Record file names
+			depth := 0
+			for j := range obj.Paths {
+				s := &obj.Paths[j]
+				if s.Name == "" {
+					depth--
+				} else {
+					if depth == 0 {
+						t.Files[s.Name] = obj
+					}
+					depth++
+				}
+			}
+
+		case 'T', 't', 'L', 'l': // text symbol
+			if n := len(t.Funcs); n > 0 {
+				t.Funcs[n-1].End = sym.Value
+			}
+			if sym.Name == "runtime.etext" || sym.Name == "etext" {
+				continue
+			}
+
+			// Count parameter and local (auto) syms
+			var np, na int
+			var end int
+		countloop:
+			for end = i + 1; end < len(t.Syms); end++ {
+				switch t.Syms[end].Type {
+				case 'T', 't', 'L', 'l', 'Z', 'z':
+					break countloop
+				case 'p':
+					np++
+				case 'a':
+					na++
+				}
+			}
+
+			// Fill in the function symbol
+			n := len(t.Funcs)
+			t.Funcs = t.Funcs[0 : n+1]
+			fn := &t.Funcs[n]
+			sym.Func = fn
+			fn.Params = make([]*Sym, 0, np)
+			fn.Locals = make([]*Sym, 0, na)
+			fn.Sym = sym
+			fn.Entry = sym.Value
+			fn.Obj = obj
+			if t.go12line != nil {
+				// All functions share the same line table.
+				// It knows how to narrow down to a specific
+				// function quickly.
+				fn.LineTable = t.go12line
+			} else if pcln != nil {
+				fn.LineTable = pcln.slice(fn.Entry)
+				pcln = fn.LineTable
+			}
+			for j := i; j < end; j++ {
+				s := &t.Syms[j]
+				switch s.Type {
+				case 'm':
+					fn.FrameSize = int(s.Value)
+				case 'p':
+					n := len(fn.Params)
+					fn.Params = fn.Params[0 : n+1]
+					fn.Params[n] = s
+				case 'a':
+					n := len(fn.Locals)
+					fn.Locals = fn.Locals[0 : n+1]
+					fn.Locals[n] = s
+				}
+			}
+			i = end - 1 // loop will i++
+		}
+	}
+
+	if t.go12line != nil && nf == 0 {
+		t.Funcs = t.go12line.go12Funcs()
+	}
+	if obj != nil {
+		obj.Funcs = t.Funcs[lastf:]
+	}
+	return &t, nil
+}
+
+// PCToFunc returns the function containing the program counter pc,
+// or nil if there is no such function.
+func (t *Table) PCToFunc(pc uint64) *Func {
+	funcs := t.Funcs
+	for len(funcs) > 0 {
+		m := len(funcs) / 2
+		fn := &funcs[m]
+		switch {
+		case pc < fn.Entry:
+			funcs = funcs[0:m]
+		case fn.Entry <= pc && pc < fn.End:
+			return fn
+		default:
+			funcs = funcs[m+1:]
+		}
+	}
+	return nil
+}
+
+// PCToLine looks up line number information for a program counter.
+// If there is no information, it returns fn == nil.
+func (t *Table) PCToLine(pc uint64) (file string, line int, fn *Func) {
+	if fn = t.PCToFunc(pc); fn == nil {
+		return
+	}
+	if t.go12line != nil {
+		file = t.go12line.go12PCToFile(pc)
+		line = t.go12line.go12PCToLine(pc)
+	} else {
+		file, line = fn.Obj.lineFromAline(fn.LineTable.PCToLine(pc))
+	}
+	return
+}
+
+// LineToPC looks up the first program counter on the given line in
+// the named file.  It returns UnknownPathError or UnknownLineError if
+// there is an error looking up this line.
+func (t *Table) LineToPC(file string, line int) (pc uint64, fn *Func, err error) {
+	obj, ok := t.Files[file]
+	if !ok {
+		return 0, nil, UnknownFileError(file)
+	}
+
+	if t.go12line != nil {
+		pc := t.go12line.go12LineToPC(file, line)
+		if pc == 0 {
+			return 0, nil, &UnknownLineError{file, line}
+		}
+		return pc, t.PCToFunc(pc), nil
+	}
+
+	abs, err := obj.alineFromLine(file, line)
+	if err != nil {
+		return
+	}
+	for i := range obj.Funcs {
+		f := &obj.Funcs[i]
+		pc := f.LineTable.LineToPC(abs, f.End)
+		if pc != 0 {
+			return pc, f, nil
+		}
+	}
+	return 0, nil, &UnknownLineError{file, line}
+}
+
+// LookupSym returns the text, data, or bss symbol with the given name,
+// or nil if no such symbol is found.
+func (t *Table) LookupSym(name string) *Sym {
+	// TODO(austin) Maybe make a map
+	for i := range t.Syms {
+		s := &t.Syms[i]
+		switch s.Type {
+		case 'T', 't', 'L', 'l', 'D', 'd', 'B', 'b':
+			if s.Name == name {
+				return s
+			}
+		}
+	}
+	return nil
+}
+
+// LookupFunc returns the text, data, or bss symbol with the given name,
+// or nil if no such symbol is found.
+func (t *Table) LookupFunc(name string) *Func {
+	for i := range t.Funcs {
+		f := &t.Funcs[i]
+		if f.Sym.Name == name {
+			return f
+		}
+	}
+	return nil
+}
+
+// SymByAddr returns the text, data, or bss symbol starting at the given address.
+func (t *Table) SymByAddr(addr uint64) *Sym {
+	for i := range t.Syms {
+		s := &t.Syms[i]
+		switch s.Type {
+		case 'T', 't', 'L', 'l', 'D', 'd', 'B', 'b':
+			if s.Value == addr {
+				return s
+			}
+		}
+	}
+	return nil
+}
+
+/*
+ * Object files
+ */
+
+// This is legacy code for Go 1.1 and earlier, which used the
+// Plan 9 format for pc-line tables. This code was never quite
+// correct. It's probably very close, and it's usually correct, but
+// we never quite found all the corner cases.
+//
+// Go 1.2 and later use a simpler format, documented at golang.org/s/go12symtab.
+
+func (o *Obj) lineFromAline(aline int) (string, int) {
+	type stackEnt struct {
+		path   string
+		start  int
+		offset int
+		prev   *stackEnt
+	}
+
+	noPath := &stackEnt{"", 0, 0, nil}
+	tos := noPath
+
+pathloop:
+	for _, s := range o.Paths {
+		val := int(s.Value)
+		switch {
+		case val > aline:
+			break pathloop
+
+		case val == 1:
+			// Start a new stack
+			tos = &stackEnt{s.Name, val, 0, noPath}
+
+		case s.Name == "":
+			// Pop
+			if tos == noPath {
+				return "<malformed symbol table>", 0
+			}
+			tos.prev.offset += val - tos.start
+			tos = tos.prev
+
+		default:
+			// Push
+			tos = &stackEnt{s.Name, val, 0, tos}
+		}
+	}
+
+	if tos == noPath {
+		return "", 0
+	}
+	return tos.path, aline - tos.start - tos.offset + 1
+}
+
+func (o *Obj) alineFromLine(path string, line int) (int, error) {
+	if line < 1 {
+		return 0, &UnknownLineError{path, line}
+	}
+
+	for i, s := range o.Paths {
+		// Find this path
+		if s.Name != path {
+			continue
+		}
+
+		// Find this line at this stack level
+		depth := 0
+		var incstart int
+		line += int(s.Value)
+	pathloop:
+		for _, s := range o.Paths[i:] {
+			val := int(s.Value)
+			switch {
+			case depth == 1 && val >= line:
+				return line - 1, nil
+
+			case s.Name == "":
+				depth--
+				if depth == 0 {
+					break pathloop
+				} else if depth == 1 {
+					line += val - incstart
+				}
+
+			default:
+				if depth == 1 {
+					incstart = val
+				}
+				depth++
+			}
+		}
+		return 0, &UnknownLineError{path, line}
+	}
+	return 0, UnknownFileError(path)
+}
+
+/*
+ * Errors
+ */
+
+// UnknownFileError represents a failure to find the specific file in
+// the symbol table.
+type UnknownFileError string
+
+func (e UnknownFileError) Error() string { return "unknown file: " + string(e) }
+
+// UnknownLineError represents a failure to map a line to a program
+// counter, either because the line is beyond the bounds of the file
+// or because there is no code on the given line.
+type UnknownLineError struct {
+	File string
+	Line int
+}
+
+func (e *UnknownLineError) Error() string {
+	return "no code at " + e.File + ":" + strconv.Itoa(e.Line)
+}
+
+// DecodingError represents an error during the decoding of
+// the symbol table.
+type DecodingError struct {
+	off int
+	msg string
+	val interface{}
+}
+
+func (e *DecodingError) Error() string {
+	msg := e.msg
+	if e.val != nil {
+		msg += fmt.Sprintf(" '%v'", e.val)
+	}
+	msg += fmt.Sprintf(" at byte %#x", e.off)
+	return msg
+}