libgo: Update to revision 15193:6fdc1974457c of master library.

From-SVN: r194692

104 files changed, 2433 insertions, 685 deletions

diff --git a/libgo/MERGE b/libgo/MERGE
index deeb596..52537f98 100644
--- a/libgo/MERGE
+++ b/libgo/MERGE
@@ -1,4 +1,4 @@
-c031aa767edf
+6fdc1974457c
 
 The first line of this file holds the Mercurial revision number of the
 last merge done from the master library sources.
diff --git a/libgo/Makefile.am b/libgo/Makefile.am
index 3da2cb4..b97a82e 100644
--- a/libgo/Makefile.am
+++ b/libgo/Makefile.am
@@ -502,6 +502,7 @@ runtime_files = \
 	runtime/go-unwind.c \
 	runtime/chan.c \
 	runtime/cpuprof.c \
+	runtime/env_posix.c \
 	runtime/lfstack.c \
 	$(runtime_lock_files) \
 	runtime/mcache.c \
@@ -1657,6 +1658,13 @@ else
 syscall_lsf_file =
 endif
 
+# GNU/Linux specific utimesnano support.
+if LIBGO_IS_LINUX
+syscall_utimesnano_file = go/syscall/libcall_linux_utimesnano.go
+else
+syscall_utimesnano_file = go/syscall/libcall_posix_utimesnano.go
+endif
+
 go_base_syscall_files = \
 	go/syscall/env_unix.go \
 	go/syscall/syscall_errno.go \
@@ -1679,6 +1687,7 @@ go_base_syscall_files = \
 	$(syscall_uname_file) \
 	$(syscall_netlink_file) \
 	$(syscall_lsf_file) \
+	$(syscall_utimesnano_file) \
 	$(GO_LIBCALL_OS_FILE) \
 	$(GO_LIBCALL_OS_ARCH_FILE) \
 	$(GO_SYSCALL_OS_FILE) \
diff --git a/libgo/Makefile.in b/libgo/Makefile.in
index 869addf..fe18b74 100644
--- a/libgo/Makefile.in
+++ b/libgo/Makefile.in
@@ -213,12 +213,13 @@ am__objects_5 = go-append.lo go-assert.lo go-assert-interface.lo \
 	go-type-float.lo go-type-identity.lo go-type-interface.lo \
 	go-type-string.lo go-typedesc-equal.lo go-typestring.lo \
 	go-unsafe-new.lo go-unsafe-newarray.lo go-unsafe-pointer.lo \
-	go-unwind.lo chan.lo cpuprof.lo lfstack.lo $(am__objects_1) \
-	mcache.lo mcentral.lo $(am__objects_2) mfinal.lo mfixalloc.lo \
-	mgc0.lo mheap.lo msize.lo panic.lo parfor.lo print.lo proc.lo \
-	runtime.lo signal_unix.lo thread.lo yield.lo $(am__objects_3) \
-	iface.lo malloc.lo map.lo mprof.lo reflect.lo runtime1.lo \
-	sema.lo sigqueue.lo string.lo time.lo $(am__objects_4)
+	go-unwind.lo chan.lo cpuprof.lo env_posix.lo lfstack.lo \
+	$(am__objects_1) mcache.lo mcentral.lo $(am__objects_2) \
+	mfinal.lo mfixalloc.lo mgc0.lo mheap.lo msize.lo panic.lo \
+	parfor.lo print.lo proc.lo runtime.lo signal_unix.lo thread.lo \
+	yield.lo $(am__objects_3) iface.lo malloc.lo map.lo mprof.lo \
+	reflect.lo runtime1.lo sema.lo sigqueue.lo string.lo time.lo \
+	$(am__objects_4)
 am_libgo_la_OBJECTS = $(am__objects_5)
 libgo_la_OBJECTS = $(am_libgo_la_OBJECTS)
 libgo_la_LINK = $(LIBTOOL) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) \
@@ -835,6 +836,7 @@ runtime_files = \
 	runtime/go-unwind.c \
 	runtime/chan.c \
 	runtime/cpuprof.c \
+	runtime/env_posix.c \
 	runtime/lfstack.c \
 	$(runtime_lock_files) \
 	runtime/mcache.c \
@@ -1840,6 +1842,10 @@ go_unicode_utf8_files = \
 
 # GNU/Linux specific socket filters.
 @LIBGO_IS_LINUX_TRUE@syscall_lsf_file = go/syscall/lsf_linux.go
+@LIBGO_IS_LINUX_FALSE@syscall_utimesnano_file = go/syscall/libcall_posix_utimesnano.go
+
+# GNU/Linux specific utimesnano support.
+@LIBGO_IS_LINUX_TRUE@syscall_utimesnano_file = go/syscall/libcall_linux_utimesnano.go
 go_base_syscall_files = \
 	go/syscall/env_unix.go \
 	go/syscall/syscall_errno.go \
@@ -1862,6 +1868,7 @@ go_base_syscall_files = \
 	$(syscall_uname_file) \
 	$(syscall_netlink_file) \
 	$(syscall_lsf_file) \
+	$(syscall_utimesnano_file) \
 	$(GO_LIBCALL_OS_FILE) \
 	$(GO_LIBCALL_OS_ARCH_FILE) \
 	$(GO_SYSCALL_OS_FILE) \
@@ -2418,6 +2425,7 @@ distclean-compile:
 
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/chan.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/cpuprof.Plo@am__quote@
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/env_posix.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/getncpu-bsd.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/getncpu-irix.Plo@am__quote@
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/getncpu-linux.Plo@am__quote@
@@ -3027,6 +3035,13 @@ cpuprof.lo: runtime/cpuprof.c
 @AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
 @am__fastdepCC_FALSE@	$(LIBTOOL)  --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -c -o cpuprof.lo `test -f 'runtime/cpuprof.c' || echo '$(srcdir)/'`runtime/cpuprof.c
 
+env_posix.lo: runtime/env_posix.c
+@am__fastdepCC_TRUE@	$(LIBTOOL)  --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -MT env_posix.lo -MD -MP -MF $(DEPDIR)/env_posix.Tpo -c -o env_posix.lo `test -f 'runtime/env_posix.c' || echo '$(srcdir)/'`runtime/env_posix.c
+@am__fastdepCC_TRUE@	$(am__mv) $(DEPDIR)/env_posix.Tpo $(DEPDIR)/env_posix.Plo
+@AMDEP_TRUE@@am__fastdepCC_FALSE@	source='runtime/env_posix.c' object='env_posix.lo' libtool=yes @AMDEPBACKSLASH@
+@AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
+@am__fastdepCC_FALSE@	$(LIBTOOL)  --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -c -o env_posix.lo `test -f 'runtime/env_posix.c' || echo '$(srcdir)/'`runtime/env_posix.c
+
 lfstack.lo: runtime/lfstack.c
 @am__fastdepCC_TRUE@	$(LIBTOOL)  --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS) -MT lfstack.lo -MD -MP -MF $(DEPDIR)/lfstack.Tpo -c -o lfstack.lo `test -f 'runtime/lfstack.c' || echo '$(srcdir)/'`runtime/lfstack.c
 @am__fastdepCC_TRUE@	$(am__mv) $(DEPDIR)/lfstack.Tpo $(DEPDIR)/lfstack.Plo
diff --git a/libgo/go/builtin/builtin.go b/libgo/go/builtin/builtin.go
index a30943b..91d263a 100644
--- a/libgo/go/builtin/builtin.go
+++ b/libgo/go/builtin/builtin.go
@@ -124,8 +124,8 @@ func append(slice []Type, elems ...Type) []Type
 func copy(dst, src []Type) int
 
 // The delete built-in function deletes the element with the specified key
-// (m[key]) from the map. If there is no such element, delete is a no-op.
-// If m is nil, delete panics.
+// (m[key]) from the map. If m is nil or there is no such element, delete
+// is a no-op.
 func delete(m map[Type]Type1, key Type)
 
 // The len built-in function returns the length of v, according to its type:
diff --git a/libgo/go/compress/flate/deflate.go b/libgo/go/compress/flate/deflate.go
index e511b50..d357fe3 100644
--- a/libgo/go/compress/flate/deflate.go
+++ b/libgo/go/compress/flate/deflate.go
@@ -22,7 +22,7 @@ const (
 	logMaxOffsetSize   = 15  // Standard DEFLATE
 	minMatchLength     = 3   // The smallest match that the compressor looks for
 	maxMatchLength     = 258 // The longest match for the compressor
-	minOffsetSize      = 1   // The shortest offset that makes any sence
+	minOffsetSize      = 1   // The shortest offset that makes any sense
 
 	// The maximum number of tokens we put into a single flat block, just too
 	// stop things from getting too large.
diff --git a/libgo/go/crypto/cipher/example_test.go b/libgo/go/crypto/cipher/example_test.go
index c888eb2..e0027ca 100644
--- a/libgo/go/crypto/cipher/example_test.go
+++ b/libgo/go/crypto/cipher/example_test.go
@@ -241,7 +241,7 @@ func ExampleStreamReader() {
 
 	// Note that this example is simplistic in that it omits any
 	// authentication of the encrypted data. It you were actually to use
-	// StreamReader in this manner, an attacker could flip arbitary bits in
+	// StreamReader in this manner, an attacker could flip arbitrary bits in
 	// the output.
 }
 
@@ -278,6 +278,6 @@ func ExampleStreamWriter() {
 
 	// Note that this example is simplistic in that it omits any
 	// authentication of the encrypted data. It you were actually to use
-	// StreamReader in this manner, an attacker could flip arbitary bits in
+	// StreamReader in this manner, an attacker could flip arbitrary bits in
 	// the decrypted result.
 }
diff --git a/libgo/go/crypto/x509/x509_test.go b/libgo/go/crypto/x509/x509_test.go
index a13f459..b2d6fe3 100644
--- a/libgo/go/crypto/x509/x509_test.go
+++ b/libgo/go/crypto/x509/x509_test.go
@@ -439,7 +439,7 @@ func TestECDSA(t *testing.T) {
 			t.Errorf("%d: public key algorithm is %v, want ECDSA", i, pka)
 		}
 		if err = cert.CheckSignatureFrom(cert); err != nil {
-			t.Errorf("%d: certificate verfication failed: %s", i, err)
+			t.Errorf("%d: certificate verification failed: %s", i, err)
 		}
 	}
 }
@@ -519,7 +519,7 @@ func TestVerifyCertificateWithDSASignature(t *testing.T) {
 	}
 	// test cert is self-signed
 	if err = cert.CheckSignatureFrom(cert); err != nil {
-		t.Fatalf("DSA Certificate verfication failed: %s", err)
+		t.Fatalf("DSA Certificate verification failed: %s", err)
 	}
 }
 
diff --git a/libgo/go/database/sql/fakedb_test.go b/libgo/go/database/sql/fakedb_test.go
index aec5727..c38ba7c 100644
--- a/libgo/go/database/sql/fakedb_test.go
+++ b/libgo/go/database/sql/fakedb_test.go
@@ -42,9 +42,10 @@ type fakeDriver struct {
 type fakeDB struct {
 	name string
 
-	mu     sync.Mutex
-	free   []*fakeConn
-	tables map[string]*table
+	mu      sync.Mutex
+	free    []*fakeConn
+	tables  map[string]*table
+	badConn bool
 }
 
 type table struct {
@@ -83,6 +84,7 @@ type fakeConn struct {
 	stmtsMade   int
 	stmtsClosed int
 	numPrepare  int
+	bad         bool
 }
 
 func (c *fakeConn) incrStat(v *int) {
@@ -122,7 +124,9 @@ func init() {
 
 // Supports dsn forms:
 //    <dbname>
-//    <dbname>;<opts>  (no currently supported options)
+//    <dbname>;<opts>  (only currently supported option is `badConn`,
+//                      which causes driver.ErrBadConn to be returned on
+//                      every other conn.Begin())
 func (d *fakeDriver) Open(dsn string) (driver.Conn, error) {
 	parts := strings.Split(dsn, ";")
 	if len(parts) < 1 {
@@ -135,7 +139,12 @@ func (d *fakeDriver) Open(dsn string) (driver.Conn, error) {
 	d.mu.Lock()
 	d.openCount++
 	d.mu.Unlock()
-	return &fakeConn{db: db}, nil
+	conn := &fakeConn{db: db}
+
+	if len(parts) >= 2 && parts[1] == "badConn" {
+		conn.bad = true
+	}
+	return conn, nil
 }
 
 func (d *fakeDriver) getDB(name string) *fakeDB {
@@ -199,7 +208,20 @@ func (db *fakeDB) columnType(table, column string) (typ string, ok bool) {
 	return "", false
 }
 
+func (c *fakeConn) isBad() bool {
+	// if not simulating bad conn, do nothing
+	if !c.bad {
+		return false
+	}
+	// alternate between bad conn and not bad conn
+	c.db.badConn = !c.db.badConn
+	return c.db.badConn
+}
+
 func (c *fakeConn) Begin() (driver.Tx, error) {
+	if c.isBad() {
+		return nil, driver.ErrBadConn
+	}
 	if c.currTx != nil {
 		return nil, errors.New("already in a transaction")
 	}
diff --git a/libgo/go/database/sql/sql.go b/libgo/go/database/sql/sql.go
index b0cba94..e7c7780 100644
--- a/libgo/go/database/sql/sql.go
+++ b/libgo/go/database/sql/sql.go
@@ -266,7 +266,7 @@ func (db *DB) connIfFree(wanted driver.Conn) (conn driver.Conn, ok bool) {
 var putConnHook func(*DB, driver.Conn)
 
 // putConn adds a connection to the db's free pool.
-// err is optionally the last error that occured on this connection.
+// err is optionally the last error that occurred on this connection.
 func (db *DB) putConn(c driver.Conn, err error) {
 	if err == driver.ErrBadConn {
 		// Don't reuse bad connections.
@@ -426,7 +426,7 @@ func (db *DB) begin() (tx *Tx, err error) {
 	txi, err := ci.Begin()
 	if err != nil {
 		db.putConn(ci, err)
-		return nil, fmt.Errorf("sql: failed to Begin transaction: %v", err)
+		return nil, err
 	}
 	return &Tx{
 		db:  db,
diff --git a/libgo/go/database/sql/sql_test.go b/libgo/go/database/sql/sql_test.go
index 1bfb590..b702b85 100644
--- a/libgo/go/database/sql/sql_test.go
+++ b/libgo/go/database/sql/sql_test.go
@@ -402,6 +402,39 @@ func TestTxQueryInvalid(t *testing.T) {
 	}
 }
 
+// Tests fix for issue 4433, that retries in Begin happen when
+// conn.Begin() returns ErrBadConn
+func TestTxErrBadConn(t *testing.T) {
+	db, err := Open("test", fakeDBName+";badConn")
+	if err != nil {
+		t.Fatalf("Open: %v", err)
+	}
+	if _, err := db.Exec("WIPE"); err != nil {
+		t.Fatalf("exec wipe: %v", err)
+	}
+	defer closeDB(t, db)
+	exec(t, db, "CREATE|t1|name=string,age=int32,dead=bool")
+	stmt, err := db.Prepare("INSERT|t1|name=?,age=?")
+	if err != nil {
+		t.Fatalf("Stmt, err = %v, %v", stmt, err)
+	}
+	defer stmt.Close()
+	tx, err := db.Begin()
+	if err != nil {
+		t.Fatalf("Begin = %v", err)
+	}
+	txs := tx.Stmt(stmt)
+	defer txs.Close()
+	_, err = txs.Exec("Bobby", 7)
+	if err != nil {
+		t.Fatalf("Exec = %v", err)
+	}
+	err = tx.Commit()
+	if err != nil {
+		t.Fatalf("Commit = %v", err)
+	}
+}
+
 // Tests fix for issue 2542, that we release a lock when querying on
 // a closed connection.
 func TestIssue2542Deadlock(t *testing.T) {
diff --git a/libgo/go/debug/elf/file.go b/libgo/go/debug/elf/file.go
index f462375..eb3d72f 100644
--- a/libgo/go/debug/elf/file.go
+++ b/libgo/go/debug/elf/file.go
@@ -272,7 +272,8 @@ func NewFile(r io.ReaderAt) (*File, error) {
 		shnum = int(hdr.Shnum)
 		shstrndx = int(hdr.Shstrndx)
 	}
-	if shstrndx < 0 || shstrndx >= shnum {
+
+	if shnum > 0 && shoff > 0 && (shstrndx < 0 || shstrndx >= shnum) {
 		return nil, &FormatError{0, "invalid ELF shstrndx", shstrndx}
 	}
 
@@ -367,6 +368,10 @@ func NewFile(r io.ReaderAt) (*File, error) {
 		f.Sections[i] = s
 	}
 
+	if len(f.Sections) == 0 {
+		return f, nil
+	}
+
 	// Load section header string table.
 	shstrtab, err := f.Sections[shstrndx].Data()
 	if err != nil {
diff --git a/libgo/go/debug/elf/file_test.go b/libgo/go/debug/elf/file_test.go
index 810a2f9..f9aa726 100644
--- a/libgo/go/debug/elf/file_test.go
+++ b/libgo/go/debug/elf/file_test.go
@@ -5,10 +5,14 @@
 package elf
 
 import (
+	"bytes"
+	"compress/gzip"
 	"debug/dwarf"
 	"encoding/binary"
+	"io"
 	"net"
 	"os"
+	"path"
 	"reflect"
 	"runtime"
 	"testing"
@@ -121,15 +125,49 @@ var fileTests = []fileTest{
 		},
 		[]string{"libc.so.6"},
 	},
+	{
+		"testdata/hello-world-core.gz",
+		FileHeader{ELFCLASS64, ELFDATA2LSB, EV_CURRENT, ELFOSABI_NONE, 0x0, binary.LittleEndian, ET_CORE, EM_X86_64, 0x0},
+		[]SectionHeader{},
+		[]ProgHeader{
+			{Type: PT_NOTE, Flags: 0x0, Off: 0x3f8, Vaddr: 0x0, Paddr: 0x0, Filesz: 0x8ac, Memsz: 0x0, Align: 0x0},
+			{Type: PT_LOAD, Flags: PF_X + PF_R, Off: 0x1000, Vaddr: 0x400000, Paddr: 0x0, Filesz: 0x0, Memsz: 0x1000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_R, Off: 0x1000, Vaddr: 0x401000, Paddr: 0x0, Filesz: 0x1000, Memsz: 0x1000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_W + PF_R, Off: 0x2000, Vaddr: 0x402000, Paddr: 0x0, Filesz: 0x1000, Memsz: 0x1000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_X + PF_R, Off: 0x3000, Vaddr: 0x7f54078b8000, Paddr: 0x0, Filesz: 0x0, Memsz: 0x1b5000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: 0x0, Off: 0x3000, Vaddr: 0x7f5407a6d000, Paddr: 0x0, Filesz: 0x0, Memsz: 0x1ff000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_R, Off: 0x3000, Vaddr: 0x7f5407c6c000, Paddr: 0x0, Filesz: 0x4000, Memsz: 0x4000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_W + PF_R, Off: 0x7000, Vaddr: 0x7f5407c70000, Paddr: 0x0, Filesz: 0x2000, Memsz: 0x2000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_W + PF_R, Off: 0x9000, Vaddr: 0x7f5407c72000, Paddr: 0x0, Filesz: 0x5000, Memsz: 0x5000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_X + PF_R, Off: 0xe000, Vaddr: 0x7f5407c77000, Paddr: 0x0, Filesz: 0x0, Memsz: 0x22000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_W + PF_R, Off: 0xe000, Vaddr: 0x7f5407e81000, Paddr: 0x0, Filesz: 0x3000, Memsz: 0x3000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_W + PF_R, Off: 0x11000, Vaddr: 0x7f5407e96000, Paddr: 0x0, Filesz: 0x3000, Memsz: 0x3000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_R, Off: 0x14000, Vaddr: 0x7f5407e99000, Paddr: 0x0, Filesz: 0x1000, Memsz: 0x1000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_W + PF_R, Off: 0x15000, Vaddr: 0x7f5407e9a000, Paddr: 0x0, Filesz: 0x2000, Memsz: 0x2000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_W + PF_R, Off: 0x17000, Vaddr: 0x7fff79972000, Paddr: 0x0, Filesz: 0x23000, Memsz: 0x23000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_X + PF_R, Off: 0x3a000, Vaddr: 0x7fff799f8000, Paddr: 0x0, Filesz: 0x1000, Memsz: 0x1000, Align: 0x1000},
+			{Type: PT_LOAD, Flags: PF_X + PF_R, Off: 0x3b000, Vaddr: 0xffffffffff600000, Paddr: 0x0, Filesz: 0x1000, Memsz: 0x1000, Align: 0x1000},
+		},
+		nil,
+	},
 }
 
 func TestOpen(t *testing.T) {
 	for i := range fileTests {
 		tt := &fileTests[i]
 
-		f, err := Open(tt.file)
+		var f *File
+		var err error
+		if path.Ext(tt.file) == ".gz" {
+			var r io.ReaderAt
+			if r, err = decompress(tt.file); err == nil {
+				f, err = NewFile(r)
+			}
+		} else {
+			f, err = Open(tt.file)
+		}
 		if err != nil {
-			t.Error(err)
+			t.Errorf("cannot open file %s: %v", tt.file, err)
 			continue
 		}
 		if !reflect.DeepEqual(f.FileHeader, tt.hdr) {
@@ -175,6 +213,23 @@ func TestOpen(t *testing.T) {
 	}
 }
 
+// elf.NewFile requires io.ReaderAt, which compress/gzip cannot
+// provide. Decompress the file to a bytes.Reader.
+func decompress(gz string) (io.ReaderAt, error) {
+	in, err := os.Open(gz)
+	if err != nil {
+		return nil, err
+	}
+	defer in.Close()
+	r, err := gzip.NewReader(in)
+	if err != nil {
+		return nil, err
+	}
+	var out bytes.Buffer
+	_, err = io.Copy(&out, r)
+	return bytes.NewReader(out.Bytes()), err
+}
+
 type relocationTestEntry struct {
 	entryNumber int
 	entry       *dwarf.Entry
diff --git a/libgo/go/debug/elf/testdata/hello-world-core.gz b/libgo/go/debug/elf/testdata/hello-world-core.gz
new file mode 100644
index 0000000..806af6e
--- /dev/null
+++ b/libgo/go/debug/elf/testdata/hello-world-core.gz
diff --git a/libgo/go/encoding/csv/writer.go b/libgo/go/encoding/csv/writer.go
index 17e4850..1faecb6 100644
--- a/libgo/go/encoding/csv/writer.go
+++ b/libgo/go/encoding/csv/writer.go
@@ -92,10 +92,17 @@ func (w *Writer) Write(record []string) (err error) {
 }
 
 // Flush writes any buffered data to the underlying io.Writer.
+// To check if an error occurred during the Flush, call Error.
 func (w *Writer) Flush() {
 	w.w.Flush()
 }
 
+// Error reports any error that has occurred during a previous Write or Flush.
+func (w *Writer) Error() error {
+	_, err := w.w.Write(nil)
+	return err
+}
+
 // WriteAll writes multiple CSV records to w using Write and then calls Flush.
 func (w *Writer) WriteAll(records [][]string) (err error) {
 	for _, record := range records {
diff --git a/libgo/go/encoding/csv/writer_test.go b/libgo/go/encoding/csv/writer_test.go
index 5789590..03ca6b0 100644
--- a/libgo/go/encoding/csv/writer_test.go
+++ b/libgo/go/encoding/csv/writer_test.go
@@ -6,6 +6,7 @@ package csv
 
 import (
 	"bytes"
+	"errors"
 	"testing"
 )
 
@@ -42,3 +43,30 @@ func TestWrite(t *testing.T) {
 		}
 	}
 }
+
+type errorWriter struct{}
+
+func (e errorWriter) Write(b []byte) (int, error) {
+	return 0, errors.New("Test")
+}
+
+func TestError(t *testing.T) {
+	b := &bytes.Buffer{}
+	f := NewWriter(b)
+	f.Write([]string{"abc"})
+	f.Flush()
+	err := f.Error()
+
+	if err != nil {
+		t.Errorf("Unexpected error: %s\n", err)
+	}
+
+	f = NewWriter(errorWriter{})
+	f.Write([]string{"abc"})
+	f.Flush()
+	err = f.Error()
+
+	if err == nil {
+		t.Error("Error should not be nil")
+	}
+}
diff --git a/libgo/go/encoding/gob/decode.go b/libgo/go/encoding/gob/decode.go
index 900c69d..a80d9f9 100644
--- a/libgo/go/encoding/gob/decode.go
+++ b/libgo/go/encoding/gob/decode.go
@@ -62,15 +62,15 @@ func overflow(name string) error {
 // Used only by the Decoder to read the message length.
 func decodeUintReader(r io.Reader, buf []byte) (x uint64, width int, err error) {
 	width = 1
-	_, err = r.Read(buf[0:width])
-	if err != nil {
+	n, err := io.ReadFull(r, buf[0:width])
+	if n == 0 {
 		return
 	}
 	b := buf[0]
 	if b <= 0x7f {
 		return uint64(b), width, nil
 	}
-	n := -int(int8(b))
+	n = -int(int8(b))
 	if n > uint64Size {
 		err = errBadUint
 		return
diff --git a/libgo/go/encoding/json/decode.go b/libgo/go/encoding/json/decode.go
index 1e0c8d4..b46dac9 100644
--- a/libgo/go/encoding/json/decode.go
+++ b/libgo/go/encoding/json/decode.go
@@ -125,13 +125,12 @@ func (d *decodeState) unmarshal(v interface{}) (err error) {
 	}()
 
 	rv := reflect.ValueOf(v)
-	pv := rv
-	if pv.Kind() != reflect.Ptr || pv.IsNil() {
+	if rv.Kind() != reflect.Ptr || rv.IsNil() {
 		return &InvalidUnmarshalError{reflect.TypeOf(v)}
 	}
 
 	d.scan.reset()
-	// We decode rv not pv.Elem because the Unmarshaler interface
+	// We decode rv not rv.Elem because the Unmarshaler interface
 	// test must be applied at the top level of the value.
 	d.value(rv)
 	return d.savedError
@@ -423,17 +422,12 @@ func (d *decodeState) object(v reflect.Value) {
 	v = pv
 
 	// Decoding into nil interface?  Switch to non-reflect code.
-	iv := v
-	if iv.Kind() == reflect.Interface {
-		iv.Set(reflect.ValueOf(d.objectInterface()))
+	if v.Kind() == reflect.Interface {
+		v.Set(reflect.ValueOf(d.objectInterface()))
 		return
 	}
 
 	// Check type of target: struct or map[string]T
-	var (
-		mv reflect.Value
-		sv reflect.Value
-	)
 	switch v.Kind() {
 	case reflect.Map:
 		// map must have string type
@@ -442,17 +436,15 @@ func (d *decodeState) object(v reflect.Value) {
 			d.saveError(&UnmarshalTypeError{"object", v.Type()})
 			break
 		}
-		mv = v
-		if mv.IsNil() {
-			mv.Set(reflect.MakeMap(t))
+		if v.IsNil() {
+			v.Set(reflect.MakeMap(t))
 		}
 	case reflect.Struct:
-		sv = v
 	default:
 		d.saveError(&UnmarshalTypeError{"object", v.Type()})
 	}
 
-	if !mv.IsValid() && !sv.IsValid() {
+	if !v.IsValid() {
 		d.off--
 		d.next() // skip over { } in input
 		return
@@ -484,8 +476,8 @@ func (d *decodeState) object(v reflect.Value) {
 		var subv reflect.Value
 		destring := false // whether the value is wrapped in a string to be decoded first
 
-		if mv.IsValid() {
-			elemType := mv.Type().Elem()
+		if v.Kind() == reflect.Map {
+			elemType := v.Type().Elem()
 			if !mapElem.IsValid() {
 				mapElem = reflect.New(elemType).Elem()
 			} else {
@@ -494,7 +486,7 @@ func (d *decodeState) object(v reflect.Value) {
 			subv = mapElem
 		} else {
 			var f *field
-			fields := cachedTypeFields(sv.Type())
+			fields := cachedTypeFields(v.Type())
 			for i := range fields {
 				ff := &fields[i]
 				if ff.name == key {
@@ -506,7 +498,7 @@ func (d *decodeState) object(v reflect.Value) {
 				}
 			}
 			if f != nil {
-				subv = sv
+				subv = v
 				destring = f.quoted
 				for _, i := range f.index {
 					if subv.Kind() == reflect.Ptr {
@@ -519,7 +511,7 @@ func (d *decodeState) object(v reflect.Value) {
 				}
 			} else {
 				// To give a good error, a quick scan for unexported fields in top level.
-				st := sv.Type()
+				st := v.Type()
 				for i := 0; i < st.NumField(); i++ {
 					f := st.Field(i)
 					if f.PkgPath != "" && strings.EqualFold(f.Name, key) {
@@ -546,8 +538,8 @@ func (d *decodeState) object(v reflect.Value) {
 		}
 		// Write value back to map;
 		// if using struct, subv points into struct already.
-		if mv.IsValid() {
-			mv.SetMapIndex(reflect.ValueOf(key), subv)
+		if v.Kind() == reflect.Map {
+			v.SetMapIndex(reflect.ValueOf(key), subv)
 		}
 
 		// Next token must be , or }.
diff --git a/libgo/go/exp/gotype/gotype_test.go b/libgo/go/exp/gotype/gotype_test.go
index 2d58f32..c0c2e32 100644
--- a/libgo/go/exp/gotype/gotype_test.go
+++ b/libgo/go/exp/gotype/gotype_test.go
@@ -25,7 +25,9 @@ func runTest(t *testing.T, path string) {
 	} else {
 		// package directory
 		// TODO(gri) gotype should use the build package instead
-		pkg, err := build.Import(path, "", 0)
+		ctxt := build.Default
+		ctxt.CgoEnabled = false
+		pkg, err := ctxt.Import(path, "", 0)
 		if err != nil {
 			t.Errorf("build.Import error for path = %s: %s", path, err)
 			return
@@ -50,7 +52,7 @@ var tests = []string{
 
 	// directories
 	// Note: packages that don't typecheck yet are commented out
-	// "archive/tar", // investigate
+	"archive/tar",
 	"archive/zip",
 
 	"bufio",
@@ -77,13 +79,13 @@ var tests = []string{
 	"crypto/md5",
 	"crypto/rand",
 	"crypto/rc4",
-	// "crypto/rsa", // investigate (GOARCH=386)
+	// "crypto/rsa", // intermittent failure: /home/gri/go2/src/pkg/crypto/rsa/pkcs1v15.go:21:27: undeclared name: io
 	"crypto/sha1",
 	"crypto/sha256",
 	"crypto/sha512",
 	"crypto/subtle",
 	"crypto/tls",
-	// "crypto/x509", // investigate
+	"crypto/x509",
 	"crypto/x509/pkix",
 
 	"database/sql",
@@ -99,9 +101,9 @@ var tests = []string{
 	"encoding/asn1",
 	"encoding/base32",
 	"encoding/base64",
-	// "encoding/binary", // complex() doesn't work yet
+	"encoding/binary",
 	"encoding/csv",
-	// "encoding/gob", // complex() doesn't work yet
+	"encoding/gob",
 	"encoding/hex",
 	"encoding/json",
 	"encoding/pem",
@@ -117,7 +119,7 @@ var tests = []string{
 
 	"go/ast",
 	"go/build",
-	// "go/doc", // variadic parameters don't work yet fully
+	"go/doc",
 	"go/format",
 	"go/parser",
 	"go/printer",
@@ -125,7 +127,7 @@ var tests = []string{
 	"go/token",
 
 	"hash/adler32",
-	// "hash/crc32", // investigate
+	"hash/crc32",
 	"hash/crc64",
 	"hash/fnv",
 
@@ -139,54 +141,54 @@ var tests = []string{
 	"index/suffixarray",
 
 	"io",
-	// "io/ioutil", // investigate
+	"io/ioutil",
 
 	"log",
 	"log/syslog",
 
 	"math",
-	// "math/big", // investigate
-	// "math/cmplx", // complex doesn't work yet
+	"math/big",
+	"math/cmplx",
 	"math/rand",
 
 	"mime",
 	"mime/multipart",
 
-	// "net", // depends on C files
+	// "net", // c:\go\root\src\pkg\net\interface_windows.go:54:13: invalid operation: division by zero
 	"net/http",
 	"net/http/cgi",
-	// "net/http/fcgi", // investigate
+	"net/http/fcgi",
 	"net/http/httptest",
 	"net/http/httputil",
-	// "net/http/pprof", // investigate
+	"net/http/pprof",
 	"net/mail",
-	// "net/rpc", // investigate
+	"net/rpc",
 	"net/rpc/jsonrpc",
 	"net/smtp",
 	"net/textproto",
 	"net/url",
 
-	// "path", // variadic parameters don't work yet fully
-	// "path/filepath", // investigate
+	"path",
+	"path/filepath",
 
-	// "reflect", // investigate
+	// "reflect", // unsafe.Sizeof must return size > 0 for pointer types
 
 	"regexp",
 	"regexp/syntax",
 
 	"runtime",
-	// "runtime/cgo", // import "C"
+	"runtime/cgo",
 	"runtime/debug",
 	"runtime/pprof",
 
 	"sort",
-	// "strconv", // investigate
+	// "strconv", // bug in switch case duplicate detection
 	"strings",
 
-	// "sync", // platform-specific files
-	// "sync/atomic", // platform-specific files
+	"sync",
+	"sync/atomic",
 
-	// "syscall", // platform-specific files
+	// "syscall", c:\go\root\src\pkg\syscall\syscall_windows.go:35:16: cannot convert EINVAL (constant 536870951) to error
 
 	"testing",
 	"testing/iotest",
@@ -194,10 +196,10 @@ var tests = []string{
 
 	"text/scanner",
 	"text/tabwriter",
-	// "text/template", // variadic parameters don't work yet fully
-	// "text/template/parse", // variadic parameters don't work yet fully
+	"text/template",
+	"text/template/parse",
 
-	// "time", // platform-specific files
+	// "time", // local const decls without initialization expressions
 	"unicode",
 	"unicode/utf16",
 	"unicode/utf8",
diff --git a/libgo/go/exp/locale/collate/build/trie.go b/libgo/go/exp/locale/collate/build/trie.go
index f521427..9404a34 100644
--- a/libgo/go/exp/locale/collate/build/trie.go
+++ b/libgo/go/exp/locale/collate/build/trie.go
@@ -20,7 +20,7 @@ import (
 
 const (
 	blockSize   = 64
-	blockOffset = 2 // Substract 2 blocks to compensate for the 0x80 added to continuation bytes.
+	blockOffset = 2 // Subtract 2 blocks to compensate for the 0x80 added to continuation bytes.
 )
 
 type trieHandle struct {
diff --git a/libgo/go/exp/norm/iter.go b/libgo/go/exp/norm/iter.go
index c0ab25e..def822d 100644
--- a/libgo/go/exp/norm/iter.go
+++ b/libgo/go/exp/norm/iter.go
@@ -179,7 +179,7 @@ doNorm:
 	i.rb.src.copySlice(out[outCopyStart:], inCopyStart, i.p)
 	if !i.rb.insertDecomposed(out[i.outStart:outp]) {
 		// Start over to prevent decompositions from crossing segment boundaries.
-		// This is a rare occurance.
+		// This is a rare occurrence.
 		i.p = i.inStart
 		i.info = i.rb.f.info(i.rb.src, i.p)
 	}
diff --git a/libgo/go/exp/norm/normalize_test.go b/libgo/go/exp/norm/normalize_test.go
index 8b97059..1a118f2 100644
--- a/libgo/go/exp/norm/normalize_test.go
+++ b/libgo/go/exp/norm/normalize_test.go
@@ -31,7 +31,7 @@ func runPosTests(t *testing.T, name string, f Form, fn positionFunc, tests []Pos
 		}
 		runes := []rune(test.buffer)
 		if rb.nrune != len(runes) {
-			t.Errorf("%s:%d: reorder buffer lenght is %d; want %d", name, i, rb.nrune, len(runes))
+			t.Errorf("%s:%d: reorder buffer length is %d; want %d", name, i, rb.nrune, len(runes))
 			continue
 		}
 		for j, want := range runes {
diff --git a/libgo/go/exp/norm/triegen.go b/libgo/go/exp/norm/triegen.go
index 1780ac7..52c88b0 100644
--- a/libgo/go/exp/norm/triegen.go
+++ b/libgo/go/exp/norm/triegen.go
@@ -21,7 +21,7 @@ import (
 
 const (
 	blockSize        = 64
-	blockOffset      = 2 // Substract two blocks to compensate for the 0x80 added to continuation bytes.
+	blockOffset      = 2 // Subtract two blocks to compensate for the 0x80 added to continuation bytes.
 	maxSparseEntries = 16
 )
 
diff --git a/libgo/go/exp/types/builtins.go b/libgo/go/exp/types/builtins.go
index 8826704..ed636ee 100644
--- a/libgo/go/exp/types/builtins.go
+++ b/libgo/go/exp/types/builtins.go
@@ -128,13 +128,51 @@ func (check *checker) builtin(x *operand, call *ast.CallExpr, bin *builtin, iota
 		x.mode = novalue
 
 	case _Complex:
+		if !check.complexArg(x) {
+			goto Error
+		}
+
 		var y operand
 		check.expr(&y, args[1], nil, iota)
 		if y.mode == invalid {
 			goto Error
 		}
-		// TODO(gri) handle complex(a, b) like (a + toImag(b))
-		unimplemented()
+		if !check.complexArg(&y) {
+			goto Error
+		}
+
+		check.convertUntyped(x, y.typ)
+		if x.mode == invalid {
+			goto Error
+		}
+		check.convertUntyped(&y, x.typ)
+		if y.mode == invalid {
+			goto Error
+		}
+
+		if !isIdentical(x.typ, y.typ) {
+			check.invalidArg(x.pos(), "mismatched types %s and %s", x.typ, y.typ)
+			goto Error
+		}
+
+		typ := underlying(x.typ).(*Basic)
+		if x.mode == constant && y.mode == constant {
+			x.val = binaryOpConst(x.val, toImagConst(y.val), token.ADD, typ)
+		} else {
+			x.mode = value
+		}
+
+		switch typ.Kind {
+		case Float32:
+			x.typ = Typ[Complex64]
+		case Float64:
+			x.typ = Typ[Complex128]
+		case UntypedInt, UntypedRune, UntypedFloat:
+			x.typ = Typ[UntypedComplex]
+		default:
+			check.invalidArg(x.pos(), "float32 or float64 arguments expected")
+			goto Error
+		}
 
 	case _Copy:
 		// TODO(gri) implements checks
@@ -361,3 +399,12 @@ func unparen(x ast.Expr) ast.Expr {
 	}
 	return x
 }
+
+func (check *checker) complexArg(x *operand) bool {
+	t, _ := underlying(x.typ).(*Basic)
+	if t != nil && (t.Info&IsFloat != 0 || t.Kind == UntypedInt || t.Kind == UntypedRune) {
+		return true
+	}
+	check.invalidArg(x.pos(), "%s must be a float32, float64, or an untyped non-complex numeric constant", x)
+	return false
+}
diff --git a/libgo/go/exp/types/const.go b/libgo/go/exp/types/const.go
index c678e47..d44c8fb 100644
--- a/libgo/go/exp/types/const.go
+++ b/libgo/go/exp/types/const.go
@@ -49,12 +49,17 @@ func (nilType) String() string {
 	return "nil"
 }
 
-// Frequently used constants.
+// Implementation-specific constants.
+// TODO(gri) These need to go elsewhere.
+const (
+	intBits = 32
+	ptrBits = 64
+)
+
+// Frequently used values.
 var (
-	zeroConst     = int64(0)
-	oneConst      = int64(1)
-	minusOneConst = int64(-1)
-	nilConst      = nilType{}
+	nilConst  = nilType{}
+	zeroConst = int64(0)
 )
 
 // int64 bounds
@@ -74,7 +79,7 @@ func normalizeIntConst(x *big.Int) interface{} {
 }
 
 // normalizeRatConst returns the smallest constant representation
-// for the specific value of x; either an int64, *big.Int value,
+// for the specific value of x; either an int64, *big.Int,
 // or *big.Rat value.
 //
 func normalizeRatConst(x *big.Rat) interface{} {
@@ -84,15 +89,15 @@ func normalizeRatConst(x *big.Rat) interface{} {
 	return x
 }
 
-// normalizeComplexConst returns the smallest constant representation
-// for the specific value of x; either an int64, *big.Int value, *big.Rat,
-// or complex value.
+// newComplex returns the smallest constant representation
+// for the specific value re + im*i; either an int64, *big.Int,
+// *big.Rat, or complex value.
 //
-func normalizeComplexConst(x complex) interface{} {
-	if x.im.Sign() == 0 {
-		return normalizeRatConst(x.re)
+func newComplex(re, im *big.Rat) interface{} {
+	if im.Sign() == 0 {
+		return normalizeRatConst(re)
 	}
-	return x
+	return complex{re, im}
 }
 
 // makeRuneConst returns the int64 code point for the rune literal
@@ -140,7 +145,7 @@ func makeComplexConst(lit string) interface{} {
 	n := len(lit)
 	if n > 0 && lit[n-1] == 'i' {
 		if im, ok := new(big.Rat).SetString(lit[0 : n-1]); ok {
-			return normalizeComplexConst(complex{big.NewRat(0, 1), im})
+			return newComplex(big.NewRat(0, 1), im)
 		}
 	}
 	return nil
@@ -157,6 +162,22 @@ func makeStringConst(lit string) interface{} {
 	return nil
 }
 
+// toImagConst returns the constant complex(0, x) for a non-complex x.
+func toImagConst(x interface{}) interface{} {
+	var im *big.Rat
+	switch x := x.(type) {
+	case int64:
+		im = big.NewRat(x, 1)
+	case *big.Int:
+		im = new(big.Rat).SetFrac(x, int1)
+	case *big.Rat:
+		im = x
+	default:
+		unreachable()
+	}
+	return complex{rat0, im}
+}
+
 // isZeroConst reports whether the value of constant x is 0.
 // x must be normalized.
 //
@@ -186,9 +207,6 @@ func isNegConst(x interface{}) bool {
 // of precision.
 //
 func isRepresentableConst(x interface{}, as BasicKind) bool {
-	const intBits = 32 // TODO(gri) implementation-specific constant
-	const ptrBits = 64 // TODO(gri) implementation-specific constant
-
 	switch x := x.(type) {
 	case bool:
 		return as == Bool || as == UntypedBool
@@ -370,13 +388,71 @@ func is63bit(x int64) bool {
 	return -1<<62 <= x && x <= 1<<62-1
 }
 
+// unaryOpConst returns the result of the constant evaluation op x where x is of the given type.
+func unaryOpConst(x interface{}, op token.Token, typ *Basic) interface{} {
+	switch op {
+	case token.ADD:
+		return x // nothing to do
+	case token.SUB:
+		switch x := x.(type) {
+		case int64:
+			if z := -x; z != x {
+				return z // no overflow
+			}
+			// overflow - need to convert to big.Int
+			return normalizeIntConst(new(big.Int).Neg(big.NewInt(x)))
+		case *big.Int:
+			return normalizeIntConst(new(big.Int).Neg(x))
+		case *big.Rat:
+			return normalizeRatConst(new(big.Rat).Neg(x))
+		case complex:
+			return newComplex(new(big.Rat).Neg(x.re), new(big.Rat).Neg(x.im))
+		}
+	case token.XOR:
+		var z big.Int
+		switch x := x.(type) {
+		case int64:
+			z.Not(big.NewInt(x))
+		case *big.Int:
+			z.Not(x)
+		default:
+			unreachable()
+		}
+		// For unsigned types, the result will be negative and
+		// thus "too large": We must limit the result size to
+		// the type's size.
+		if typ.Info&IsUnsigned != 0 {
+			s := uint(typ.Size) * 8
+			if s == 0 {
+				// platform-specific type
+				// TODO(gri) this needs to be factored out
+				switch typ.Kind {
+				case Uint:
+					s = intBits
+				case Uintptr:
+					s = ptrBits
+				default:
+					unreachable()
+				}
+			}
+			// z &^= (-1)<<s
+			z.AndNot(&z, new(big.Int).Lsh(big.NewInt(-1), s))
+		}
+		return normalizeIntConst(&z)
+	case token.NOT:
+		return !x.(bool)
+	}
+	unreachable()
+	return nil
+}
+
 // binaryOpConst returns the result of the constant evaluation x op y;
-// both operands must be of the same "kind" (boolean, numeric, or string).
-// If intDiv is true, division (op == token.QUO) is using integer division
+// both operands must be of the same constant "kind" (boolean, numeric, or string).
+// If typ is an integer type, division (op == token.QUO) is using integer division
 // (and the result is guaranteed to be integer) rather than floating-point
 // division. Division by zero leads to a run-time panic.
 //
-func binaryOpConst(x, y interface{}, op token.Token, intDiv bool) interface{} {
+func binaryOpConst(x, y interface{}, op token.Token, typ *Basic) interface{} {
 	x, y = matchConst(x, y)
 
 	switch x := x.(type) {
@@ -387,8 +463,6 @@ func binaryOpConst(x, y interface{}, op token.Token, intDiv bool) interface{} {
 			return x && y
 		case token.LOR:
 			return x || y
-		default:
-			unreachable()
 		}
 
 	case int64:
@@ -415,7 +489,7 @@ func binaryOpConst(x, y interface{}, op token.Token, intDiv bool) interface{} {
 		case token.REM:
 			return x % y
 		case token.QUO:
-			if intDiv {
+			if typ.Info&IsInteger != 0 {
 				return x / y
 			}
 			return normalizeRatConst(new(big.Rat).SetFrac(big.NewInt(x), big.NewInt(y)))
@@ -427,8 +501,6 @@ func binaryOpConst(x, y interface{}, op token.Token, intDiv bool) interface{} {
 			return x ^ y
 		case token.AND_NOT:
 			return x &^ y
-		default:
-			unreachable()
 		}
 
 	case *big.Int:
@@ -444,7 +516,7 @@ func binaryOpConst(x, y interface{}, op token.Token, intDiv bool) interface{} {
 		case token.REM:
 			z.Rem(x, y)
 		case token.QUO:
-			if intDiv {
+			if typ.Info&IsInteger != 0 {
 				z.Quo(x, y)
 			} else {
 				return normalizeRatConst(new(big.Rat).SetFrac(x, y))
@@ -517,7 +589,7 @@ func binaryOpConst(x, y interface{}, op token.Token, intDiv bool) interface{} {
 		default:
 			unreachable()
 		}
-		return normalizeComplexConst(complex{&re, &im})
+		return newComplex(&re, &im)
 
 	case string:
 		if op == token.ADD {
diff --git a/libgo/go/exp/types/errors.go b/libgo/go/exp/types/errors.go
index 1a16595..b1b6436 100644
--- a/libgo/go/exp/types/errors.go
+++ b/libgo/go/exp/types/errors.go
@@ -266,15 +266,8 @@ func writeType(buf *bytes.Buffer, typ Type) {
 		buf.WriteByte('*')
 		writeType(buf, t.Base)
 
-	case *tuple:
-		buf.WriteByte('(')
-		for i, typ := range t.list {
-			if i > 0 {
-				buf.WriteString("; ")
-			}
-			writeType(buf, typ)
-		}
-		buf.WriteByte(')')
+	case *Result:
+		writeParams(buf, t.Values, false)
 
 	case *Signature:
 		buf.WriteString("func")
diff --git a/libgo/go/exp/types/expr.go b/libgo/go/exp/types/expr.go
index e1f627b..2f5f2b3 100644
--- a/libgo/go/exp/types/expr.go
+++ b/libgo/go/exp/types/expr.go
@@ -19,7 +19,6 @@ import (
 // - at the moment, iota is passed around almost everywhere - in many places we know it cannot be used
 
 // TODO(gri) API issues
-// - clients need access to result type information (tuples)
 // - clients need access to constant values
 // - clients need access to built-in type information
 
@@ -212,21 +211,11 @@ func (check *checker) unary(x *operand, op token.Token) {
 	}
 
 	if x.mode == constant {
-		switch op {
-		case token.ADD:
-			// nothing to do
-		case token.SUB:
-			x.val = binaryOpConst(zeroConst, x.val, token.SUB, false)
-		case token.XOR:
-			x.val = binaryOpConst(minusOneConst, x.val, token.XOR, false)
-		case token.NOT:
-			x.val = !x.val.(bool)
-		default:
-			unreachable() // operators where checked by check.op
-		}
+		typ := underlying(x.typ).(*Basic)
+		x.val = unaryOpConst(x.val, op, typ)
 		// Typed constants must be representable in
 		// their type after each constant operation.
-		check.isRepresentable(x, underlying(x.typ).(*Basic))
+		check.isRepresentable(x, typ)
 		return
 	}
 
@@ -304,6 +293,8 @@ func (check *checker) convertUntyped(x *operand, target Type) {
 		if !x.isNil() {
 			goto Error
 		}
+	default:
+		unreachable()
 	}
 
 	x.typ = target
@@ -332,7 +323,7 @@ func (check *checker) comparison(x, y *operand, op token.Token) {
 	}
 
 	if !valid {
-		check.invalidOp(x.pos(), "cannot compare %s and %s", x, y)
+		check.invalidOp(x.pos(), "cannot compare %s %s %s", x, op, y)
 		x.mode = invalid
 		return
 	}
@@ -465,10 +456,11 @@ func (check *checker) binary(x, y *operand, op token.Token, hint Type) {
 	}
 
 	if x.mode == constant && y.mode == constant {
-		x.val = binaryOpConst(x.val, y.val, op, isInteger(x.typ))
+		typ := underlying(x.typ).(*Basic)
+		x.val = binaryOpConst(x.val, y.val, op, typ)
 		// Typed constants must be representable in
 		// their type after each constant operation.
-		check.isRepresentable(x, underlying(x.typ).(*Basic))
+		check.isRepresentable(x, typ)
 		return
 	}
 
@@ -554,9 +546,15 @@ func (check *checker) indexedElts(elts []ast.Expr, typ Type, length int64, iota
 	return max
 }
 
-func (check *checker) argument(sig *Signature, i int, arg ast.Expr) {
+// argument typechecks passing an argument arg (if arg != nil) or
+// x (if arg == nil) to the i'th parameter of the given signature.
+// If passSlice is set, the argument is followed by ... in the call.
+//
+func (check *checker) argument(sig *Signature, i int, arg ast.Expr, x *operand, passSlice bool) {
+	// determine parameter
 	var par *ast.Object
-	if n := len(sig.Params); i < n {
+	n := len(sig.Params)
+	if i < n {
 		par = sig.Params[i]
 	} else if sig.IsVariadic {
 		par = sig.Params[n-1]
@@ -565,16 +563,32 @@ func (check *checker) argument(sig *Signature, i int, arg ast.Expr) {
 		return
 	}
 
-	// TODO(gri) deal with ... last argument
-	var z, x operand
+	// determine argument
+	var z operand
 	z.mode = variable
-	z.expr = nil            // TODO(gri) can we do better here?
-	z.typ = par.Type.(Type) // TODO(gri) should become something like checkObj(&z, ...) eventually
-	check.expr(&x, arg, z.typ, -1)
+	z.expr = nil // TODO(gri) can we do better here? (for good error messages)
+	z.typ = par.Type.(Type)
+
+	if arg != nil {
+		check.expr(x, arg, z.typ, -1)
+	}
 	if x.mode == invalid {
 		return // ignore this argument
 	}
-	check.assignOperand(&z, &x)
+
+	// check last argument of the form x...
+	if passSlice {
+		if i+1 != n {
+			check.errorf(x.pos(), "can only use ... with matching parameter")
+			return // ignore this argument
+		}
+		// spec: "If the final argument is assignable to a slice type []T,
+		// it may be passed unchanged as the value for a ...T parameter if
+		// the argument is followed by ..."
+		z.typ = &Slice{Elt: z.typ} // change final parameter type to []T
+	}
+
+	check.assignOperand(&z, x)
 }
 
 func (check *checker) recordType(x *operand) {
@@ -584,7 +598,7 @@ func (check *checker) recordType(x *operand) {
 }
 
 // rawExpr typechecks expression e and initializes x with the expression
-// value or type. If an error occured, x.mode is set to invalid.
+// value or type. If an error occurred, x.mode is set to invalid.
 // A hint != nil is used as operand type for untyped shifted operands;
 // iota >= 0 indicates that the expression is part of a constant declaration.
 // cycleOk indicates whether it is ok for a type expression to refer to itself.
@@ -653,7 +667,7 @@ func (check *checker) rawExpr(x *operand, e ast.Expr, hint Type, iota int, cycle
 		x.typ = obj.Type.(Type)
 
 	case *ast.Ellipsis:
-		// ellipses are handled explictly where they are legal
+		// ellipses are handled explicitly where they are legal
 		// (array composite literals and parameter lists)
 		check.errorf(e.Pos(), "invalid use of '...'")
 		goto Error
@@ -1052,25 +1066,79 @@ func (check *checker) rawExpr(x *operand, e ast.Expr, hint Type, iota int, cycle
 			check.conversion(x, e, x.typ, iota)
 		} else if sig, ok := underlying(x.typ).(*Signature); ok {
 			// check parameters
-			// TODO(gri)
-			// - deal with single multi-valued function arguments: f(g())
-			// - variadic functions only partially addressed
-			for i, arg := range e.Args {
-				check.argument(sig, i, arg)
+
+			// If we have a trailing ... at the end of the parameter
+			// list, the last argument must match the parameter type
+			// []T of a variadic function parameter x ...T.
+			passSlice := false
+			if e.Ellipsis.IsValid() {
+				if sig.IsVariadic {
+					passSlice = true
+				} else {
+					check.errorf(e.Ellipsis, "cannot use ... in call to %s", e.Fun)
+					// ok to continue
+				}
 			}
 
-			// determine result
-			x.mode = value
-			if len(sig.Results) == 1 {
-				x.typ = sig.Results[0].Type.(Type)
+			// If we have a single argument that is a function call
+			// we need to handle it separately. Determine if this
+			// is the case without checking the argument.
+			var call *ast.CallExpr
+			if len(e.Args) == 1 {
+				call, _ = unparen(e.Args[0]).(*ast.CallExpr)
+			}
+
+			n := 0 // parameter count
+			if call != nil {
+				// We have a single argument that is a function call.
+				check.expr(x, call, nil, -1)
+				if x.mode == invalid {
+					goto Error // TODO(gri): we can do better
+				}
+				if t, _ := x.typ.(*Result); t != nil {
+					// multiple result values
+					n = len(t.Values)
+					for i, obj := range t.Values {
+						x.mode = value
+						x.expr = nil // TODO(gri) can we do better here? (for good error messages)
+						x.typ = obj.Type.(Type)
+						check.argument(sig, i, nil, x, passSlice && i+1 == n)
+					}
+				} else {
+					// single result value
+					n = 1
+					check.argument(sig, 0, nil, x, passSlice)
+				}
+
 			} else {
-				// TODO(gri) change Signature representation to use tuples,
-				//           then this conversion is not required
-				list := make([]Type, len(sig.Results))
-				for i, obj := range sig.Results {
-					list[i] = obj.Type.(Type)
+				// We don't have a single argument or it is not a function call.
+				n = len(e.Args)
+				for i, arg := range e.Args {
+					check.argument(sig, i, arg, x, passSlice && i+1 == n)
 				}
-				x.typ = &tuple{list: list}
+			}
+
+			// determine if we have enough arguments
+			if sig.IsVariadic {
+				// a variadic function accepts an "empty"
+				// last argument: count one extra
+				n++
+			}
+			if n < len(sig.Params) {
+				check.errorf(e.Fun.Pos(), "too few arguments in call to %s", e.Fun)
+				// ok to continue
+			}
+
+			// determine result
+			switch len(sig.Results) {
+			case 0:
+				x.mode = novalue
+			case 1:
+				x.mode = value
+				x.typ = sig.Results[0].Type.(Type)
+			default:
+				x.mode = value
+				x.typ = &Result{Values: sig.Results}
 			}
 
 		} else if bin, ok := x.typ.(*builtin); ok {
@@ -1216,14 +1284,14 @@ func (check *checker) rawTyp(e ast.Expr, cycleOk, nilOk bool) Type {
 }
 
 // typOrNil is like rawExpr but reports an error if e doesn't represents a type or the predeclared value nil.
-// It returns e's type, nil, or Typ[Invalid] if an error occured.
+// It returns e's type, nil, or Typ[Invalid] if an error occurred.
 //
 func (check *checker) typOrNil(e ast.Expr, cycleOk bool) Type {
 	return check.rawTyp(e, cycleOk, true)
 }
 
 // typ is like rawExpr but reports an error if e doesn't represents a type.
-// It returns e's type, or Typ[Invalid] if an error occured.
+// It returns e's type, or Typ[Invalid] if an error occurred.
 //
 func (check *checker) typ(e ast.Expr, cycleOk bool) Type {
 	return check.rawTyp(e, cycleOk, false)
diff --git a/libgo/go/exp/types/operand.go b/libgo/go/exp/types/operand.go
index 1a5e517..f8ddd84 100644
--- a/libgo/go/exp/types/operand.go
+++ b/libgo/go/exp/types/operand.go
@@ -182,7 +182,14 @@ func (x *operand) isAssignable(T Type) bool {
 	if isUntyped(Vu) {
 		switch t := Tu.(type) {
 		case *Basic:
-			return x.mode == constant && isRepresentableConst(x.val, t.Kind)
+			if x.mode == constant {
+				return isRepresentableConst(x.val, t.Kind)
+			}
+			// The result of a comparison is an untyped boolean,
+			// but may not be a constant.
+			if Vb, _ := Vu.(*Basic); Vb != nil {
+				return Vb.Kind == UntypedBool && isBoolean(Tu)
+			}
 		case *Interface:
 			return x.isNil() || len(t.Methods) == 0
 		case *Pointer, *Signature, *Slice, *Map, *Chan:
diff --git a/libgo/go/exp/types/predicates.go b/libgo/go/exp/types/predicates.go
index 2c1a991..ff6825b 100644
--- a/libgo/go/exp/types/predicates.go
+++ b/libgo/go/exp/types/predicates.go
@@ -225,25 +225,28 @@ func deref(typ Type) Type {
 }
 
 // defaultType returns the default "typed" type for an "untyped" type;
-// it returns the argument typ for all other types.
+// it returns the incoming type for all other types. If there is no
+// corresponding untyped type, the result is Typ[Invalid].
+//
 func defaultType(typ Type) Type {
 	if t, ok := typ.(*Basic); ok {
-		var k BasicKind
+		k := Invalid
 		switch t.Kind {
+		// case UntypedNil:
+		//      There is no default type for nil. For a good error message,
+		//      catch this case before calling this function.
 		case UntypedBool:
 			k = Bool
-		case UntypedRune:
-			k = Rune
 		case UntypedInt:
 			k = Int
+		case UntypedRune:
+			k = Rune
 		case UntypedFloat:
 			k = Float64
 		case UntypedComplex:
 			k = Complex128
 		case UntypedString:
 			k = String
-		default:
-			unreachable()
 		}
 		typ = Typ[k]
 	}
diff --git a/libgo/go/exp/types/stmt.go b/libgo/go/exp/types/stmt.go
index e2c6448..7f9d45e 100644
--- a/libgo/go/exp/types/stmt.go
+++ b/libgo/go/exp/types/stmt.go
@@ -12,9 +12,9 @@ import (
 )
 
 func (check *checker) assignOperand(z, x *operand) {
-	if t, ok := x.typ.(*tuple); ok {
+	if t, ok := x.typ.(*Result); ok {
 		// TODO(gri) elsewhere we use "assignment count mismatch" (consolidate)
-		check.errorf(x.pos(), "%d-valued expression %s used as single value", len(t.list), x)
+		check.errorf(x.pos(), "%d-valued expression %s used as single value", len(t.Values), x)
 		x.mode = invalid
 		return
 	}
@@ -95,7 +95,12 @@ func (check *checker) assign1to1(lhs, rhs ast.Expr, x *operand, decl bool, iota
 		if x.mode != invalid {
 			typ = x.typ
 			if obj.Kind == ast.Var && isUntyped(typ) {
-				typ = defaultType(typ)
+				if x.isNil() {
+					check.errorf(x.pos(), "use of untyped nil")
+					x.mode = invalid
+				} else {
+					typ = defaultType(typ)
+				}
 			}
 		}
 		obj.Type = typ
@@ -177,12 +182,12 @@ func (check *checker) assignNtoM(lhs, rhs []ast.Expr, decl bool, iota int) {
 			return
 		}
 
-		if t, ok := x.typ.(*tuple); ok && len(lhs) == len(t.list) {
+		if t, ok := x.typ.(*Result); ok && len(lhs) == len(t.Values) {
 			// function result
 			x.mode = value
-			for i, typ := range t.list {
+			for i, obj := range t.Values {
 				x.expr = nil // TODO(gri) should do better here
-				x.typ = typ
+				x.typ = obj.Type.(Type)
 				check.assign1to1(lhs[i], nil, &x, decl, iota)
 			}
 			return
@@ -427,25 +432,58 @@ func (check *checker) stmt(s ast.Stmt) {
 	case *ast.SwitchStmt:
 		check.optionalStmt(s.Init)
 		var x operand
-		if s.Tag != nil {
-			check.expr(&x, s.Tag, nil, -1)
-		} else {
-			// TODO(gri) should provide a position (see IncDec) for good error messages
-			x.mode = constant
-			x.typ = Typ[UntypedBool]
-			x.val = true
+		tag := s.Tag
+		if tag == nil {
+			// use fake true tag value and position it at the opening { of the switch
+			tag = &ast.Ident{NamePos: s.Body.Lbrace, Name: "true", Obj: Universe.Lookup("true")}
 		}
+		check.expr(&x, tag, nil, -1)
 
 		check.multipleDefaults(s.Body.List)
+		seen := make(map[interface{}]token.Pos)
 		for _, s := range s.Body.List {
 			clause, _ := s.(*ast.CaseClause)
 			if clause == nil {
 				continue // error reported before
 			}
-			for _, expr := range clause.List {
-				var y operand
-				check.expr(&y, expr, nil, -1)
-				// TODO(gri) x and y must be comparable
+			if x.mode != invalid {
+				for _, expr := range clause.List {
+					x := x // copy of x (don't modify original)
+					var y operand
+					check.expr(&y, expr, nil, -1)
+					if y.mode == invalid {
+						continue // error reported before
+					}
+					// If we have a constant case value, it must appear only
+					// once in the switch statement. Determine if there is a
+					// duplicate entry, but only report an error if there are
+					// no other errors.
+					var dupl token.Pos
+					if y.mode == constant {
+						// TODO(gri) This code doesn't work correctly for
+						//           large integer, floating point, or
+						//           complex values - the respective struct
+						//           comparisons are shallow. Need to use a
+						//           hash function to index the map.
+						dupl = seen[y.val]
+						seen[y.val] = y.pos()
+					}
+					// TODO(gri) The convertUntyped call pair below appears in other places. Factor!
+					// Order matters: By comparing y against x, error positions are at the case values.
+					check.convertUntyped(&y, x.typ)
+					if y.mode == invalid {
+						continue // error reported before
+					}
+					check.convertUntyped(&x, y.typ)
+					if x.mode == invalid {
+						continue // error reported before
+					}
+					check.comparison(&y, &x, token.EQL)
+					if y.mode != invalid && dupl.IsValid() {
+						check.errorf(y.pos(), "%s is duplicate case (previous at %s)",
+							&y, check.fset.Position(dupl))
+					}
+				}
 			}
 			check.stmtList(clause.Body)
 		}
diff --git a/libgo/go/exp/types/testdata/builtins.src b/libgo/go/exp/types/testdata/builtins.src
index a07af89..a951853 100644
--- a/libgo/go/exp/types/testdata/builtins.src
+++ b/libgo/go/exp/types/testdata/builtins.src
@@ -46,10 +46,33 @@ func _close() {
 }
 
 func _complex() {
-	_0 := complex /* ERROR "argument" */ ()
-	_1 := complex /* ERROR "argument" */ (1)
-	_2 := complex(1, 2)
-	// TODO(gri) add tests checking types
+	var i32 int32
+	var f32 float32
+	var f64 float64
+	var c64 complex64
+	_ = complex /* ERROR "argument" */ ()
+	_ = complex /* ERROR "argument" */ (1)
+	_ = complex(true /* ERROR "invalid argument" */ , 0)
+	_ = complex(i32 /* ERROR "invalid argument" */ , 0)
+	_ = complex("foo" /* ERROR "invalid argument" */ , 0)
+	_ = complex(c64 /* ERROR "invalid argument" */ , 0)
+	_ = complex(0, true /* ERROR "invalid argument" */ )
+	_ = complex(0, i32 /* ERROR "invalid argument" */ )
+	_ = complex(0, "foo" /* ERROR "invalid argument" */ )
+	_ = complex(0, c64 /* ERROR "invalid argument" */ )
+	_ = complex(f32, f32)
+	_ = complex(f32, 1)
+	_ = complex(f32, 1.0)
+	_ = complex(f32, 'a')
+	_ = complex(f64, f64)
+	_ = complex(f64, 1)
+	_ = complex(f64, 1.0)
+	_ = complex(f64, 'a')
+	_ = complex(f32 /* ERROR "mismatched types" */, f64)
+	_ = complex(f64 /* ERROR "mismatched types" */, f32)
+	_ = complex(1, 1)
+	_ = complex(1, 1.1)
+	_ = complex(1, 'a')
 	complex /* ERROR "not used" */ (1, 2)
 }
 
diff --git a/libgo/go/exp/types/testdata/decls1.src b/libgo/go/exp/types/testdata/decls1.src
index be92709..3baed67 100644
--- a/libgo/go/exp/types/testdata/decls1.src
+++ b/libgo/go/exp/types/testdata/decls1.src
@@ -46,7 +46,7 @@ var (
 	s14 = i << j /* ERROR "must be unsigned" */ 
 	s18 = math.Pi * 10.0
 	s19 = s1 /* ERROR "cannot call" */ ()
- 	s20 = f0 /* ERROR "used as single value" */ ()
+ 	s20 = f0 /* ERROR "no value" */ ()
 	s21 = f6(1, s1, i)
 	s22 = f6(1, s1, uu /* ERROR "cannot assign" */ )
 	
@@ -68,7 +68,7 @@ var (
 	t17 math /* ERROR "not a type" */ .Pi
 	t18 float64 = math.Pi * 10.0
 	t19 int = t1 /* ERROR "cannot call" */ ()
-	t20 int = f0 /* ERROR "used as single value" */ ()
+	t20 int = f0 /* ERROR "no value" */ ()
 )
 
 // Various more complex expressions
@@ -94,6 +94,7 @@ var (
 	v10 byte = 1024 /* ERROR "overflows" */
 	v11 = xx/yy*yy - xx
 	v12 = true && false
+	v13 = nil /* ERROR "use of untyped nil" */
 )
 
 // Multiple assignment expressions
diff --git a/libgo/go/exp/types/testdata/expr0.src b/libgo/go/exp/types/testdata/expr0.src
index 0ed314a..8b2eb04 100644
--- a/libgo/go/exp/types/testdata/expr0.src
+++ b/libgo/go/exp/types/testdata/expr0.src
@@ -63,6 +63,7 @@ var (
 	u16 = &u0
 	u17 = *u16
 	u18 = <-u16 /* ERROR "cannot receive" */
+	u19 = ^uint(0)
 
 	// float64
 	f0 = float64(1)
@@ -131,5 +132,4 @@ var (
 	ch7 = <-ch
 	ch8 = <-rc
 	ch9 = <-sc /* ERROR "cannot receive" */
-
-)
\ No newline at end of file
+)
diff --git a/libgo/go/exp/types/testdata/expr2.src b/libgo/go/exp/types/testdata/expr2.src
index 4bc2769..674be40 100644
--- a/libgo/go/exp/types/testdata/expr2.src
+++ b/libgo/go/exp/types/testdata/expr2.src
@@ -6,6 +6,17 @@
 
 package expr2
 
+func _bool() {
+	const t = true == true
+	const f = true == false
+	_ = t /* ERROR "cannot compare" */ < f
+	_ = 0 /* ERROR "cannot convert" */ == t
+	var b bool
+	var x, y float32
+	b = x < y
+	_ = struct{b bool}{x < y}
+}
+
 // corner cases
 var (
 	v0 = nil /* ERROR "cannot compare" */ == nil
diff --git a/libgo/go/exp/types/testdata/expr3.src b/libgo/go/exp/types/testdata/expr3.src
index a5ea4d2..35905c4 100644
--- a/libgo/go/exp/types/testdata/expr3.src
+++ b/libgo/go/exp/types/testdata/expr3.src
@@ -286,3 +286,64 @@ func type_asserts() {
 	_ = t.(T2 /* ERROR "wrong type for method m" */ )
 	_ = t.(I2 /* ERROR "wrong type for method m" */ )
 }
+
+func f0() {}
+func f1(x int) {}
+func f2(u float32, s string) {}
+func fs(s []byte) {}
+func fv(x ...int) {}
+func fi(x ... interface{}) {}
+
+func g0() {}
+func g1() int { return 0}
+func g2() (u float32, s string) { return }
+func gs() []byte { return nil }
+
+func _calls() {
+	var x int
+	var y float32
+	var s []int
+
+	f0()
+	_ = f0 /* ERROR "used as value" */ ()
+	f0(g0 /* ERROR "too many arguments" */ )
+
+	f1(0)
+	f1(x)
+	f1(10.0)
+	f1 /* ERROR "too few arguments" */ ()
+	f1(x, y /* ERROR "too many arguments" */ )
+	f1(s /* ERROR "cannot assign" */ )
+	f1(x ... /* ERROR "cannot use ..." */ )
+	f1(g0 /* ERROR "used as value" */ ())
+	f1(g1())
+	// f1(g2()) // TODO(gri) missing position in error message
+
+	f2 /* ERROR "too few arguments" */ ()
+	f2 /* ERROR "too few arguments" */ (3.14)
+	f2(3.14, "foo")
+	f2(x /* ERROR "cannot assign" */ , "foo")
+	f2(g0 /* ERROR "used as value" */ ())
+	f2 /* ERROR "too few arguments" */ (g1 /* ERROR "cannot assign" */ ())
+	f2(g2())
+
+	fs /* ERROR "too few arguments" */ ()
+	fs(g0 /* ERROR "used as value" */ ())
+	fs(g1 /* ERROR "cannot assign" */ ())
+	// fs(g2()) // TODO(gri) missing position in error message
+	fs(gs())
+
+	fv()
+	fv(1, 2.0, x)
+	fv(s /* ERROR "cannot assign" */ )
+	fv(s...)
+	fv(1, s /* ERROR "can only use ... with matching parameter" */ ...)
+	fv(gs /* ERROR "cannot assign" */ ())
+	fv(gs /* ERROR "cannot assign" */ ()...)
+
+	fi()
+	fi(1, 2.0, x, 3.14, "foo")
+	fi(g2())
+	fi(0, g2)
+	fi(0, g2 /* ERROR "2-valued expression" */ ())
+}
\ No newline at end of file
diff --git a/libgo/go/exp/types/testdata/stmt0.src b/libgo/go/exp/types/testdata/stmt0.src
index d3cc3ac..c0e0236 100644
--- a/libgo/go/exp/types/testdata/stmt0.src
+++ b/libgo/go/exp/types/testdata/stmt0.src
@@ -101,7 +101,31 @@ func _switches() {
 	default /* ERROR "multiple defaults" */ :
 	}
 
-	// TODO(gri) more tests
+	switch {
+	case 1  /* ERROR "cannot convert" */ :
+	}
+
+	switch int32(x) {
+	case 1, 2:
+	case x /* ERROR "cannot compare" */ :
+	}
+
+	switch x {
+	case 1 /* ERROR "overflows int" */ << 100:
+	}
+
+	switch x {
+	case 1:
+	case 1 /* ERROR "duplicate case" */ :
+	case 2, 3, 4:
+	case 1 /* ERROR "duplicate case" */ :
+	}
+
+	// TODO(gri) duplicate 64bit values that don't fit into an int64 are not yet detected
+	switch uint64(x) {
+	case 1<<64-1:
+	case 1<<64-1:
+	}
 }
 
 type I interface {
diff --git a/libgo/go/exp/types/types.go b/libgo/go/exp/types/types.go
index 83a0826..6e4a987 100644
--- a/libgo/go/exp/types/types.go
+++ b/libgo/go/exp/types/types.go
@@ -141,15 +141,15 @@ type Pointer struct {
 	Base Type
 }
 
-// A tuple represents a multi-value function return.
-// TODO(gri) use better name to avoid confusion (Go doesn't have tuples).
-type tuple struct {
+// A Result represents a (multi-value) function call result.
+// TODO(gri) consider using an empty Result (Values == nil)
+//           as representation for the novalue operand mode.
+type Result struct {
 	implementsType
-	list []Type
+	Values ObjList // Signature.Results of the function called
 }
 
 // A Signature represents a user-defined function type func(...) (...).
-// TODO(gri) consider using "tuples" to represent parameters and results (see comment on tuples).
 type Signature struct {
 	implementsType
 	Recv       *ast.Object // nil if not a method
diff --git a/libgo/go/exp/types/types_test.go b/libgo/go/exp/types/types_test.go
index 62ca19b..361f636 100644
--- a/libgo/go/exp/types/types_test.go
+++ b/libgo/go/exp/types/types_test.go
@@ -155,7 +155,7 @@ var testExprs = []testEntry{
 	dup("-f(10, 20)"),
 	dup("f(x + y, +3.1415)"),
 	{"func(a, b int) {}", "(func literal)"},
-	{"func(a, b int) []int {}()[x]", "(func literal)()[x]"},
+	{"func(a, b int) []int {}(1, 2)[x]", "(func literal)(1, 2)[x]"},
 	{"[]int{1, 2, 3}", "(composite literal)"},
 	{"[]int{1, 2, 3}[x:]", "(composite literal)[x:]"},
 	{"i.([]string)", "i.(...)"},
diff --git a/libgo/go/fmt/fmt_test.go b/libgo/go/fmt/fmt_test.go
index 3406113..ab06465 100644
--- a/libgo/go/fmt/fmt_test.go
+++ b/libgo/go/fmt/fmt_test.go
@@ -476,6 +476,11 @@ var fmttests = []struct {
 
 	// Used to crash because nByte didn't allow for a sign.
 	{"%b", int64(-1 << 63), "-1000000000000000000000000000000000000000000000000000000000000000"},
+
+	// Complex fmt used to leave the plus flag set for future entries in the array
+	// causing +2+0i and +3+0i instead of 2+0i and 3+0i.
+	{"%v", []complex64{1, 2, 3}, "[(1+0i) (2+0i) (3+0i)]"},
+	{"%v", []complex128{1, 2, 3}, "[(1+0i) (2+0i) (3+0i)]"},
 }
 
 func TestSprintf(t *testing.T) {
diff --git a/libgo/go/fmt/format.go b/libgo/go/fmt/format.go
index ce80116..c3d7605 100644
--- a/libgo/go/fmt/format.go
+++ b/libgo/go/fmt/format.go
@@ -396,7 +396,7 @@ func (f *fmt) fmt_f64(v float64) { f.formatFloat(v, 'f', doPrec(f, 6), 64) }
 // fmt_g64 formats a float64 in the 'f' or 'e' form according to size.
 func (f *fmt) fmt_g64(v float64) { f.formatFloat(v, 'g', doPrec(f, -1), 64) }
 
-// fmt_g64 formats a float64 in the 'f' or 'E' form according to size.
+// fmt_G64 formats a float64 in the 'f' or 'E' form according to size.
 func (f *fmt) fmt_G64(v float64) { f.formatFloat(v, 'G', doPrec(f, -1), 64) }
 
 // fmt_fb64 formats a float64 in the form -123p3 (exponent is power of 2).
@@ -428,6 +428,7 @@ func (f *fmt) fmt_fb32(v float32) { f.formatFloat(float64(v), 'b', 0, 32) }
 func (f *fmt) fmt_c64(v complex64, verb rune) {
 	f.buf.WriteByte('(')
 	r := real(v)
+	oldPlus := f.plus
 	for i := 0; ; i++ {
 		switch verb {
 		case 'e':
@@ -447,6 +448,7 @@ func (f *fmt) fmt_c64(v complex64, verb rune) {
 		f.plus = true
 		r = imag(v)
 	}
+	f.plus = oldPlus
 	f.buf.Write(irparenBytes)
 }
 
@@ -454,6 +456,7 @@ func (f *fmt) fmt_c64(v complex64, verb rune) {
 func (f *fmt) fmt_c128(v complex128, verb rune) {
 	f.buf.WriteByte('(')
 	r := real(v)
+	oldPlus := f.plus
 	for i := 0; ; i++ {
 		switch verb {
 		case 'e':
@@ -473,5 +476,6 @@ func (f *fmt) fmt_c128(v complex128, verb rune) {
 		f.plus = true
 		r = imag(v)
 	}
+	f.plus = oldPlus
 	f.buf.Write(irparenBytes)
 }
diff --git a/libgo/go/fmt/scan.go b/libgo/go/fmt/scan.go
index 62de3a2..6a282c8 100644
--- a/libgo/go/fmt/scan.go
+++ b/libgo/go/fmt/scan.go
@@ -337,7 +337,10 @@ func (r *readRune) readByte() (b byte, err error) {
 		r.pending--
 		return
 	}
-	_, err = r.reader.Read(r.pendBuf[0:1])
+	n, err := io.ReadFull(r.reader, r.pendBuf[0:1])
+	if n != 1 {
+		return 0, err
+	}
 	return r.pendBuf[0], err
 }
 
diff --git a/libgo/go/go/ast/ast.go b/libgo/go/go/ast/ast.go
index e1582c3..bf533d1 100644
--- a/libgo/go/go/ast/ast.go
+++ b/libgo/go/go/ast/ast.go
@@ -555,7 +555,7 @@ type (
 
 	// A DeclStmt node represents a declaration in a statement list.
 	DeclStmt struct {
-		Decl Decl
+		Decl Decl // *GenDecl with CONST, TYPE, or VAR token
 	}
 
 	// An EmptyStmt node represents an empty statement.
diff --git a/libgo/go/go/build/build.go b/libgo/go/go/build/build.go
index e65d845..a164425 100644
--- a/libgo/go/go/build/build.go
+++ b/libgo/go/go/build/build.go
@@ -222,6 +222,8 @@ var cgoEnabled = map[string]bool{
 	"linux/arm":     true,
 	"netbsd/386":    true,
 	"netbsd/amd64":  true,
+	"openbsd/386":   true,
+	"openbsd/amd64": true,
 	"windows/386":   true,
 	"windows/amd64": true,
 }
@@ -424,6 +426,13 @@ func (ctxt *Context) Import(path string, srcDir string, mode ImportMode) (*Packa
 		if strings.HasPrefix(path, "/") {
 			return p, fmt.Errorf("import %q: cannot import absolute path", path)
 		}
+
+		// tried records the location of unsucsessful package lookups
+		var tried struct {
+			goroot string
+			gopath []string
+		}
+
 		// Determine directory from import path.
 		if ctxt.GOROOT != "" {
 			dir := ctxt.joinPath(ctxt.GOROOT, "src", "pkg", path)
@@ -435,6 +444,7 @@ func (ctxt *Context) Import(path string, srcDir string, mode ImportMode) (*Packa
 				p.Root = ctxt.GOROOT
 				goto Found
 			}
+			tried.goroot = dir
 		}
 		for _, root := range ctxt.gopath() {
 			dir := ctxt.joinPath(root, "src", path)
@@ -445,8 +455,28 @@ func (ctxt *Context) Import(path string, srcDir string, mode ImportMode) (*Packa
 				p.Root = root
 				goto Found
 			}
+			tried.gopath = append(tried.gopath, dir)
+		}
+
+		// package was not found
+		var paths []string
+		if tried.goroot != "" {
+			paths = append(paths, fmt.Sprintf("\t%s (from $GOROOT)", tried.goroot))
+		} else {
+			paths = append(paths, "\t($GOROOT not set)")
+		}
+		var i int
+		var format = "\t%s (from $GOPATH)"
+		for ; i < len(tried.gopath); i++ {
+			if i > 0 {
+				format = "\t%s"
+			}
+			paths = append(paths, fmt.Sprintf(format, tried.gopath[i]))
+		}
+		if i == 0 {
+			paths = append(paths, "\t($GOPATH not set)")
 		}
-		return p, fmt.Errorf("import %q: cannot find package", path)
+		return p, fmt.Errorf("cannot find package %q in any of:\n%s", path, strings.Join(paths, "\n"))
 	}
 
 Found:
diff --git a/libgo/go/go/doc/comment.go b/libgo/go/go/doc/comment.go
index 51e2bf7..c4b7e6a 100644
--- a/libgo/go/go/doc/comment.go
+++ b/libgo/go/go/doc/comment.go
@@ -229,7 +229,8 @@ type block struct {
 var nonAlphaNumRx = regexp.MustCompile(`[^a-zA-Z0-9]`)
 
 func anchorID(line string) string {
-	return nonAlphaNumRx.ReplaceAllString(line, "_")
+	// Add a "hdr-" prefix to avoid conflicting with IDs used for package symbols.
+	return "hdr-" + nonAlphaNumRx.ReplaceAllString(line, "_")
 }
 
 // ToHTML converts comment text to formatted HTML.
diff --git a/libgo/go/go/doc/example.go b/libgo/go/go/doc/example.go
index e5752bb..9fc0b41 100644
--- a/libgo/go/go/doc/example.go
+++ b/libgo/go/go/doc/example.go
@@ -119,8 +119,29 @@ func playExample(file *ast.File, body *ast.BlockStmt) *ast.File {
 		return nil
 	}
 
-	// Find unresolved identifiers
+	// Find top-level declarations in the file.
+	topDecls := make(map[*ast.Object]bool)
+	for _, decl := range file.Decls {
+		switch d := decl.(type) {
+		case *ast.FuncDecl:
+			topDecls[d.Name.Obj] = true
+		case *ast.GenDecl:
+			for _, spec := range d.Specs {
+				switch s := spec.(type) {
+				case *ast.TypeSpec:
+					topDecls[s.Name.Obj] = true
+				case *ast.ValueSpec:
+					for _, id := range s.Names {
+						topDecls[id.Obj] = true
+					}
+				}
+			}
+		}
+	}
+
+	// Find unresolved identifiers and uses of top-level declarations.
 	unresolved := make(map[string]bool)
+	usesTopDecl := false
 	ast.Inspect(body, func(n ast.Node) bool {
 		// For an expression like fmt.Println, only add "fmt" to the
 		// set of unresolved names.
@@ -130,11 +151,19 @@ func playExample(file *ast.File, body *ast.BlockStmt) *ast.File {
 			}
 			return false
 		}
-		if id, ok := n.(*ast.Ident); ok && id.Obj == nil {
-			unresolved[id.Name] = true
+		if id, ok := n.(*ast.Ident); ok {
+			if id.Obj == nil {
+				unresolved[id.Name] = true
+			} else if topDecls[id.Obj] {
+				usesTopDecl = true
+			}
 		}
 		return true
 	})
+	if usesTopDecl {
+		// We don't support examples that are not self-contained (yet).
+		return nil
+	}
 
 	// Remove predeclared identifiers from unresolved list.
 	for n := range unresolved {
diff --git a/libgo/go/go/format/format.go b/libgo/go/go/format/format.go
index 286296e..65b0e4e 100644
--- a/libgo/go/go/format/format.go
+++ b/libgo/go/go/format/format.go
@@ -46,7 +46,7 @@ func Node(dst io.Writer, fset *token.FileSet, node interface{}) error {
 	// Sort imports if necessary.
 	if file != nil && hasUnsortedImports(file) {
 		// Make a copy of the AST because ast.SortImports is destructive.
-		// TODO(gri) Do this more efficently.
+		// TODO(gri) Do this more efficiently.
 		var buf bytes.Buffer
 		err := config.Fprint(&buf, fset, file)
 		if err != nil {
diff --git a/libgo/go/go/printer/nodes.go b/libgo/go/go/printer/nodes.go
index cd5b67b..3bed0cc 100644
--- a/libgo/go/go/printer/nodes.go
+++ b/libgo/go/go/printer/nodes.go
@@ -83,7 +83,7 @@ func (p *printer) setComment(g *ast.CommentGroup) {
 	// don't overwrite any pending comment in the p.comment cache
 	// (there may be a pending comment when a line comment is
 	// immediately followed by a lead comment with no other
-	// tokens inbetween)
+	// tokens between)
 	if p.commentOffset == infinity {
 		p.nextComment() // get comment ready for use
 	}
diff --git a/libgo/go/go/token/position.go b/libgo/go/go/token/position.go
index fc45c1e..f5d9995 100644
--- a/libgo/go/go/token/position.go
+++ b/libgo/go/go/token/position.go
@@ -295,9 +295,9 @@ type FileSet struct {
 
 // NewFileSet creates a new file set.
 func NewFileSet() *FileSet {
-	s := new(FileSet)
-	s.base = 1 // 0 == NoPos
-	return s
+	return &FileSet{
+		base: 1, // 0 == NoPos
+	}
 }
 
 // Base returns the minimum base offset that must be provided to
@@ -367,8 +367,10 @@ func searchFiles(a []*File, x int) int {
 }
 
 func (s *FileSet) file(p Pos) *File {
+	s.mutex.RLock()
 	// common case: p is in last file
 	if f := s.last; f != nil && f.base <= int(p) && int(p) <= f.base+f.size {
+		s.mutex.RUnlock()
 		return f
 	}
 	// p is not in last file - search all files
@@ -376,10 +378,14 @@ func (s *FileSet) file(p Pos) *File {
 		f := s.files[i]
 		// f.base <= int(p) by definition of searchFiles
 		if int(p) <= f.base+f.size {
-			s.last = f
+			s.mutex.RUnlock()
+			s.mutex.Lock()
+			s.last = f // race is ok - s.last is only a cache
+			s.mutex.Unlock()
 			return f
 		}
 	}
+	s.mutex.RUnlock()
 	return nil
 }
 
@@ -389,9 +395,7 @@ func (s *FileSet) file(p Pos) *File {
 //
 func (s *FileSet) File(p Pos) (f *File) {
 	if p != NoPos {
-		s.mutex.RLock()
 		f = s.file(p)
-		s.mutex.RUnlock()
 	}
 	return
 }
@@ -399,11 +403,9 @@ func (s *FileSet) File(p Pos) (f *File) {
 // Position converts a Pos in the fileset into a general Position.
 func (s *FileSet) Position(p Pos) (pos Position) {
 	if p != NoPos {
-		s.mutex.RLock()
 		if f := s.file(p); f != nil {
 			pos = f.position(p)
 		}
-		s.mutex.RUnlock()
 	}
 	return
 }
diff --git a/libgo/go/go/token/position_test.go b/libgo/go/go/token/position_test.go
index 160107d..1d36c22 100644
--- a/libgo/go/go/token/position_test.go
+++ b/libgo/go/go/token/position_test.go
@@ -6,6 +6,8 @@ package token
 
 import (
 	"fmt"
+	"math/rand"
+	"sync"
 	"testing"
 )
 
@@ -179,3 +181,52 @@ func TestFiles(t *testing.T) {
 		}
 	}
 }
+
+// FileSet.File should return nil if Pos is past the end of the FileSet.
+func TestFileSetPastEnd(t *testing.T) {
+	fset := NewFileSet()
+	for _, test := range tests {
+		fset.AddFile(test.filename, fset.Base(), test.size)
+	}
+	if f := fset.File(Pos(fset.Base())); f != nil {
+		t.Errorf("expected nil, got %v", f)
+	}
+}
+
+func TestFileSetCacheUnlikely(t *testing.T) {
+	fset := NewFileSet()
+	offsets := make(map[string]int)
+	for _, test := range tests {
+		offsets[test.filename] = fset.Base()
+		fset.AddFile(test.filename, fset.Base(), test.size)
+	}
+	for file, pos := range offsets {
+		f := fset.File(Pos(pos))
+		if f.Name() != file {
+			t.Errorf("expecting %q at position %d, got %q", file, pos, f.Name())
+		}
+	}
+}
+
+// issue 4345. Test concurrent use of FileSet.Pos does not trigger a
+// race in the FileSet position cache.
+func TestFileSetRace(t *testing.T) {
+	fset := NewFileSet()
+	for i := 0; i < 100; i++ {
+		fset.AddFile(fmt.Sprintf("file-%d", i), fset.Base(), 1031)
+	}
+	max := int32(fset.Base())
+	var stop sync.WaitGroup
+	r := rand.New(rand.NewSource(7))
+	for i := 0; i < 2; i++ {
+		r := rand.New(rand.NewSource(r.Int63()))
+		stop.Add(1)
+		go func() {
+			for i := 0; i < 1000; i++ {
+				fset.Position(Pos(r.Int31n(max)))
+			}
+			stop.Done()
+		}()
+	}
+	stop.Wait()
+}
diff --git a/libgo/go/io/io.go b/libgo/go/io/io.go
index bddb701..859adaf 100644
--- a/libgo/go/io/io.go
+++ b/libgo/go/io/io.go
@@ -468,6 +468,11 @@ func (s *SectionReader) ReadAt(p []byte, off int64) (n int, err error) {
 	off += s.base
 	if max := s.limit - off; int64(len(p)) > max {
 		p = p[0:max]
+		n, err = s.r.ReadAt(p, off)
+		if err == nil {
+			err = EOF
+		}
+		return n, err
 	}
 	return s.r.ReadAt(p, off)
 }
diff --git a/libgo/go/io/io_test.go b/libgo/go/io/io_test.go
index 1e671b5..f3ec050 100644
--- a/libgo/go/io/io_test.go
+++ b/libgo/go/io/io_test.go
@@ -203,3 +203,35 @@ func TestTeeReader(t *testing.T) {
 		t.Errorf("closed tee: ReadFull(r, dst) = %d, %v; want 0, EPIPE", n, err)
 	}
 }
+
+func TestSectionReader_ReadAt(tst *testing.T) {
+	dat := "a long sample data, 1234567890"
+	tests := []struct {
+		data   string
+		off    int
+		n      int
+		bufLen int
+		at     int
+		exp    string
+		err    error
+	}{
+		{data: "", off: 0, n: 10, bufLen: 2, at: 0, exp: "", err: EOF},
+		{data: dat, off: 0, n: len(dat), bufLen: 0, at: 0, exp: "", err: nil},
+		{data: dat, off: len(dat), n: 1, bufLen: 1, at: 0, exp: "", err: EOF},
+		{data: dat, off: 0, n: len(dat) + 2, bufLen: len(dat), at: 0, exp: dat, err: nil},
+		{data: dat, off: 0, n: len(dat), bufLen: len(dat) / 2, at: 0, exp: dat[:len(dat)/2], err: nil},
+		{data: dat, off: 0, n: len(dat), bufLen: len(dat), at: 0, exp: dat, err: nil},
+		{data: dat, off: 0, n: len(dat), bufLen: len(dat) / 2, at: 2, exp: dat[2 : 2+len(dat)/2], err: nil},
+		{data: dat, off: 3, n: len(dat), bufLen: len(dat) / 2, at: 2, exp: dat[5 : 5+len(dat)/2], err: nil},
+		{data: dat, off: 3, n: len(dat) / 2, bufLen: len(dat)/2 - 2, at: 2, exp: dat[5 : 5+len(dat)/2-2], err: nil},
+		{data: dat, off: 3, n: len(dat) / 2, bufLen: len(dat)/2 + 2, at: 2, exp: dat[5 : 5+len(dat)/2-2], err: EOF},
+	}
+	for i, t := range tests {
+		r := strings.NewReader(t.data)
+		s := NewSectionReader(r, int64(t.off), int64(t.n))
+		buf := make([]byte, t.bufLen)
+		if n, err := s.ReadAt(buf, int64(t.at)); n != len(t.exp) || string(buf[:n]) != t.exp || err != t.err {
+			tst.Fatalf("%d: ReadAt(%d) = %q, %v; expected %q, %v", i, t.at, buf[:n], err, t.exp, t.err)
+		}
+	}
+}
diff --git a/libgo/go/log/syslog/syslog_test.go b/libgo/go/log/syslog/syslog_test.go
index 4c0bf1f..67d7103 100644
--- a/libgo/go/log/syslog/syslog_test.go
+++ b/libgo/go/log/syslog/syslog_test.go
@@ -20,13 +20,14 @@ var serverAddr string
 
 func runSyslog(c net.PacketConn, done chan<- string) {
 	var buf [4096]byte
-	var rcvd string = ""
+	var rcvd string
 	for {
-		n, _, err := c.ReadFrom(buf[0:])
-		if err != nil || n == 0 {
+		c.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
+		n, _, err := c.ReadFrom(buf[:])
+		rcvd += string(buf[:n])
+		if err != nil {
 			break
 		}
-		rcvd += string(buf[0:n])
 	}
 	done <- rcvd
 }
@@ -37,7 +38,6 @@ func startServer(done chan<- string) {
 		log.Fatalf("net.ListenPacket failed udp :0 %v", e)
 	}
 	serverAddr = c.LocalAddr().String()
-	c.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
 	go runSyslog(c, done)
 }
 
diff --git a/libgo/go/math/all_test.go b/libgo/go/math/all_test.go
index cdea803..0d8b10f 100644
--- a/libgo/go/math/all_test.go
+++ b/libgo/go/math/all_test.go
@@ -2281,6 +2281,13 @@ func TestLog2(t *testing.T) {
 			t.Errorf("Log2(%g) = %g, want %g", vflogSC[i], f, logSC[i])
 		}
 	}
+	for i := -1074; i <= 1023; i++ {
+		f := Ldexp(1, i)
+		l := Log2(f)
+		if l != float64(i) {
+			t.Errorf("Log2(2**%d) = %g, want %d", i, l, i)
+		}
+	}
 }
 
 func TestModf(t *testing.T) {
diff --git a/libgo/go/math/big/int.go b/libgo/go/math/big/int.go
index 95c0d58..63a4536 100644
--- a/libgo/go/math/big/int.go
+++ b/libgo/go/math/big/int.go
@@ -51,6 +51,13 @@ func (z *Int) SetInt64(x int64) *Int {
 	return z
 }
 
+// SetUint64 sets z to x and returns z.
+func (z *Int) SetUint64(x uint64) *Int {
+	z.abs = z.abs.setUint64(uint64(x))
+	z.neg = false
+	return z
+}
+
 // NewInt allocates and returns a new Int set to x.
 func NewInt(x int64) *Int {
 	return new(Int).SetInt64(x)
@@ -519,6 +526,19 @@ func (x *Int) Int64() int64 {
 	return v
 }
 
+// Uint64 returns the int64 representation of x.
+// If x cannot be represented in an uint64, the result is undefined.
+func (x *Int) Uint64() uint64 {
+	if len(x.abs) == 0 {
+		return 0
+	}
+	v := uint64(x.abs[0])
+	if _W == 32 && len(x.abs) > 1 {
+		v |= uint64(x.abs[1]) << 32
+	}
+	return v
+}
+
 // SetString sets z to the value of s, interpreted in the given base,
 // and returns z and a boolean indicating success. If SetString fails,
 // the value of z is undefined but the returned value is nil.
diff --git a/libgo/go/math/big/int_test.go b/libgo/go/math/big/int_test.go
index d3c5a0e..fd6d152 100644
--- a/libgo/go/math/big/int_test.go
+++ b/libgo/go/math/big/int_test.go
@@ -1135,6 +1135,36 @@ func TestInt64(t *testing.T) {
 	}
 }
 
+var uint64Tests = []uint64{
+	0,
+	1,
+	4294967295,
+	4294967296,
+	8589934591,
+	8589934592,
+	9223372036854775807,
+	9223372036854775808,
+	18446744073709551615, // 1<<64 - 1
+}
+
+func TestUint64(t *testing.T) {
+	in := new(Int)
+	for i, testVal := range uint64Tests {
+		in.SetUint64(testVal)
+		out := in.Uint64()
+
+		if out != testVal {
+			t.Errorf("#%d got %d want %d", i, out, testVal)
+		}
+
+		str := fmt.Sprint(testVal)
+		strOut := in.String()
+		if strOut != str {
+			t.Errorf("#%d.String got %s want %s", i, strOut, str)
+		}
+	}
+}
+
 var bitwiseTests = []struct {
 	x, y                 string
 	and, or, xor, andNot string
diff --git a/libgo/go/math/big/nat.go b/libgo/go/math/big/nat.go
index 13a623a..9d09f97 100644
--- a/libgo/go/math/big/nat.go
+++ b/libgo/go/math/big/nat.go
@@ -826,7 +826,7 @@ func (x nat) string(charset string) string {
 
 // Convert words of q to base b digits in s. If q is large, it is recursively "split in half"
 // by nat/nat division using tabulated divisors. Otherwise, it is converted iteratively using
-// repeated nat/Word divison.
+// repeated nat/Word division.
 //
 // The iterative method processes n Words by n divW() calls, each of which visits every Word in the
 // incrementally shortened q for a total of n + (n-1) + (n-2) ... + 2 + 1, or n(n+1)/2 divW()'s.
diff --git a/libgo/go/math/log10.go b/libgo/go/math/log10.go
index 3d2cec6..d880ec204 100644
--- a/libgo/go/math/log10.go
+++ b/libgo/go/math/log10.go
@@ -26,5 +26,6 @@ func Log2(x float64) float64 {
 }
 
 func log2(x float64) float64 {
-	return Log(x) * (1 / Ln2)
+	frac, exp := Frexp(x)
+	return Log(frac)*(1/Ln2) + float64(exp)
 }
diff --git a/libgo/go/net/cgo_openbsd.go b/libgo/go/net/cgo_openbsd.go
new file mode 100644
index 0000000..aeaf8e5
--- /dev/null
+++ b/libgo/go/net/cgo_openbsd.go
@@ -0,0 +1,14 @@
+// Copyright 2011 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 net
+
+/*
+#include <netdb.h>
+*/
+import "C"
+
+func cgoAddrInfoFlags() C.int {
+	return C.AI_CANONNAME
+}
diff --git a/libgo/go/net/cgo_unix.go b/libgo/go/net/cgo_unix.go
index 69daedc..a4d96a8 100644
--- a/libgo/go/net/cgo_unix.go
+++ b/libgo/go/net/cgo_unix.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin freebsd linux netbsd
+// +build darwin freebsd linux netbsd openbsd
 
 package net
 
diff --git a/libgo/go/net/conn_test.go b/libgo/go/net/conn_test.go
index 037ce80..f733a81 100644
--- a/libgo/go/net/conn_test.go
+++ b/libgo/go/net/conn_test.go
@@ -17,8 +17,8 @@ var connTests = []struct {
 	addr string
 }{
 	{"tcp", "127.0.0.1:0"},
-	{"unix", "/tmp/gotest.net"},
-	{"unixpacket", "/tmp/gotest.net"},
+	{"unix", "/tmp/gotest.net1"},
+	{"unixpacket", "/tmp/gotest.net2"},
 }
 
 func TestConnAndListener(t *testing.T) {
@@ -41,7 +41,13 @@ func TestConnAndListener(t *testing.T) {
 			return
 		}
 		ln.Addr()
-		defer ln.Close()
+		defer func(ln net.Listener, net, addr string) {
+			ln.Close()
+			switch net {
+			case "unix", "unixpacket":
+				os.Remove(addr)
+			}
+		}(ln, tt.net, tt.addr)
 
 		done := make(chan int)
 		go transponder(t, ln, done)
@@ -68,10 +74,6 @@ func TestConnAndListener(t *testing.T) {
 		}
 
 		<-done
-		switch tt.net {
-		case "unix", "unixpacket":
-			os.Remove(tt.addr)
-		}
 	}
 }
 
diff --git a/libgo/go/net/dial.go b/libgo/go/net/dial.go
index 0c46084..c1eb983 100644
--- a/libgo/go/net/dial.go
+++ b/libgo/go/net/dial.go
@@ -238,7 +238,7 @@ func ListenPacket(net, laddr string) (PacketConn, error) {
 		if a != nil {
 			la = a.(*UnixAddr)
 		}
-		return DialUnix(net, la, nil)
+		return ListenUnixgram(net, la)
 	}
 	return nil, UnknownNetworkError(net)
 }
diff --git a/libgo/go/net/dial_test.go b/libgo/go/net/dial_test.go
index 865dd62..f30dee3 100644
--- a/libgo/go/net/dial_test.go
+++ b/libgo/go/net/dial_test.go
@@ -240,7 +240,8 @@ func TestDialTimeoutFDLeak(t *testing.T) {
 		err  error
 	}
 	dials := listenerBacklog + 100
-	maxGoodConnect := listenerBacklog + 5 // empirically 131 good ones (of 128). who knows?
+	// used to be listenerBacklog + 5, but was found to be unreliable, issue 4384.
+	maxGoodConnect := listenerBacklog + runtime.NumCPU()*10
 	resc := make(chan connErr)
 	for i := 0; i < dials; i++ {
 		go func() {
diff --git a/libgo/go/net/http/client.go b/libgo/go/net/http/client.go
index 2f957d2..5ee0804 100644
--- a/libgo/go/net/http/client.go
+++ b/libgo/go/net/http/client.go
@@ -98,7 +98,9 @@ func (c *Client) send(req *Request) (*Response, error) {
 		return nil, err
 	}
 	if c.Jar != nil {
-		c.Jar.SetCookies(req.URL, resp.Cookies())
+		if rc := resp.Cookies(); len(rc) > 0 {
+			c.Jar.SetCookies(req.URL, rc)
+		}
 	}
 	return resp, err
 }
@@ -120,7 +122,10 @@ func (c *Client) send(req *Request) (*Response, error) {
 // Generally Get, Post, or PostForm will be used instead of Do.
 func (c *Client) Do(req *Request) (resp *Response, err error) {
 	if req.Method == "GET" || req.Method == "HEAD" {
-		return c.doFollowingRedirects(req)
+		return c.doFollowingRedirects(req, shouldRedirectGet)
+	}
+	if req.Method == "POST" || req.Method == "PUT" {
+		return c.doFollowingRedirects(req, shouldRedirectPost)
 	}
 	return c.send(req)
 }
@@ -166,7 +171,7 @@ func send(req *Request, t RoundTripper) (resp *Response, err error) {
 
 // True if the specified HTTP status code is one for which the Get utility should
 // automatically redirect.
-func shouldRedirect(statusCode int) bool {
+func shouldRedirectGet(statusCode int) bool {
 	switch statusCode {
 	case StatusMovedPermanently, StatusFound, StatusSeeOther, StatusTemporaryRedirect:
 		return true
@@ -174,6 +179,16 @@ func shouldRedirect(statusCode int) bool {
 	return false
 }
 
+// True if the specified HTTP status code is one for which the Post utility should
+// automatically redirect.
+func shouldRedirectPost(statusCode int) bool {
+	switch statusCode {
+	case StatusFound, StatusSeeOther:
+		return true
+	}
+	return false
+}
+
 // Get issues a GET to the specified URL.  If the response is one of the following
 // redirect codes, Get follows the redirect, up to a maximum of 10 redirects:
 //
@@ -214,12 +229,10 @@ func (c *Client) Get(url string) (resp *Response, err error) {
 	if err != nil {
 		return nil, err
 	}
-	return c.doFollowingRedirects(req)
+	return c.doFollowingRedirects(req, shouldRedirectGet)
 }
 
-func (c *Client) doFollowingRedirects(ireq *Request) (resp *Response, err error) {
-	// TODO: if/when we add cookie support, the redirected request shouldn't
-	// necessarily supply the same cookies as the original.
+func (c *Client) doFollowingRedirects(ireq *Request, shouldRedirect func(int) bool) (resp *Response, err error) {
 	var base *url.URL
 	redirectChecker := c.CheckRedirect
 	if redirectChecker == nil {
@@ -238,6 +251,9 @@ func (c *Client) doFollowingRedirects(ireq *Request) (resp *Response, err error)
 		if redirect != 0 {
 			req = new(Request)
 			req.Method = ireq.Method
+			if ireq.Method == "POST" || ireq.Method == "PUT" {
+				req.Method = "GET"
+			}
 			req.Header = make(Header)
 			req.URL, err = base.Parse(urlStr)
 			if err != nil {
@@ -321,7 +337,7 @@ func (c *Client) Post(url string, bodyType string, body io.Reader) (resp *Respon
 		return nil, err
 	}
 	req.Header.Set("Content-Type", bodyType)
-	return c.send(req)
+	return c.doFollowingRedirects(req, shouldRedirectPost)
 }
 
 // PostForm issues a POST to the specified URL, with data's keys and
@@ -371,5 +387,5 @@ func (c *Client) Head(url string) (resp *Response, err error) {
 	if err != nil {
 		return nil, err
 	}
-	return c.doFollowingRedirects(req)
+	return c.doFollowingRedirects(req, shouldRedirectGet)
 }
diff --git a/libgo/go/net/http/client_test.go b/libgo/go/net/http/client_test.go
index f4ba6a9..9514a4b 100644
--- a/libgo/go/net/http/client_test.go
+++ b/libgo/go/net/http/client_test.go
@@ -7,6 +7,7 @@
 package http_test
 
 import (
+	"bytes"
 	"crypto/tls"
 	"crypto/x509"
 	"errors"
@@ -246,6 +247,52 @@ func TestRedirects(t *testing.T) {
 	}
 }
 
+func TestPostRedirects(t *testing.T) {
+	var log struct {
+		sync.Mutex
+		bytes.Buffer
+	}
+	var ts *httptest.Server
+	ts = httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		log.Lock()
+		fmt.Fprintf(&log.Buffer, "%s %s ", r.Method, r.RequestURI)
+		log.Unlock()
+		if v := r.URL.Query().Get("code"); v != "" {
+			code, _ := strconv.Atoi(v)
+			if code/100 == 3 {
+				w.Header().Set("Location", ts.URL)
+			}
+			w.WriteHeader(code)
+		}
+	}))
+	tests := []struct {
+		suffix string
+		want   int // response code
+	}{
+		{"/", 200},
+		{"/?code=301", 301},
+		{"/?code=302", 200},
+		{"/?code=303", 200},
+		{"/?code=404", 404},
+	}
+	for _, tt := range tests {
+		res, err := Post(ts.URL+tt.suffix, "text/plain", strings.NewReader("Some content"))
+		if err != nil {
+			t.Fatal(err)
+		}
+		if res.StatusCode != tt.want {
+			t.Errorf("POST %s: status code = %d; want %d", tt.suffix, res.StatusCode, tt.want)
+		}
+	}
+	log.Lock()
+	got := log.String()
+	log.Unlock()
+	want := "POST / POST /?code=301 POST /?code=302 GET / POST /?code=303 GET / POST /?code=404 "
+	if got != want {
+		t.Errorf("Log differs.\n Got: %q\nWant: %q", got, want)
+	}
+}
+
 var expectedCookies = []*Cookie{
 	{Name: "ChocolateChip", Value: "tasty"},
 	{Name: "First", Value: "Hit"},
@@ -304,6 +351,9 @@ type TestJar struct {
 func (j *TestJar) SetCookies(u *url.URL, cookies []*Cookie) {
 	j.m.Lock()
 	defer j.m.Unlock()
+	if j.perURL == nil {
+		j.perURL = make(map[string][]*Cookie)
+	}
 	j.perURL[u.Host] = cookies
 }
 
@@ -334,8 +384,9 @@ func TestRedirectCookiesJar(t *testing.T) {
 	var ts *httptest.Server
 	ts = httptest.NewServer(echoCookiesRedirectHandler)
 	defer ts.Close()
-	c := &Client{}
-	c.Jar = &TestJar{perURL: make(map[string][]*Cookie)}
+	c := &Client{
+		Jar: new(TestJar),
+	}
 	u, _ := url.Parse(ts.URL)
 	c.Jar.SetCookies(u, []*Cookie{expectedCookies[0]})
 	resp, err := c.Get(ts.URL)
@@ -364,6 +415,69 @@ func matchReturnedCookies(t *testing.T, expected, given []*Cookie) {
 	}
 }
 
+func TestJarCalls(t *testing.T) {
+	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+		pathSuffix := r.RequestURI[1:]
+		if r.RequestURI == "/nosetcookie" {
+			return // dont set cookies for this path
+		}
+		SetCookie(w, &Cookie{Name: "name" + pathSuffix, Value: "val" + pathSuffix})
+		if r.RequestURI == "/" {
+			Redirect(w, r, "http://secondhost.fake/secondpath", 302)
+		}
+	}))
+	defer ts.Close()
+	jar := new(RecordingJar)
+	c := &Client{
+		Jar: jar,
+		Transport: &Transport{
+			Dial: func(_ string, _ string) (net.Conn, error) {
+				return net.Dial("tcp", ts.Listener.Addr().String())
+			},
+		},
+	}
+	_, err := c.Get("http://firsthost.fake/")
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, err = c.Get("http://firsthost.fake/nosetcookie")
+	if err != nil {
+		t.Fatal(err)
+	}
+	got := jar.log.String()
+	want := `Cookies("http://firsthost.fake/")
+SetCookie("http://firsthost.fake/", [name=val])
+Cookies("http://secondhost.fake/secondpath")
+SetCookie("http://secondhost.fake/secondpath", [namesecondpath=valsecondpath])
+Cookies("http://firsthost.fake/nosetcookie")
+`
+	if got != want {
+		t.Errorf("Got Jar calls:\n%s\nWant:\n%s", got, want)
+	}
+}
+
+// RecordingJar keeps a log of calls made to it, without
+// tracking any cookies.
+type RecordingJar struct {
+	mu  sync.Mutex
+	log bytes.Buffer
+}
+
+func (j *RecordingJar) SetCookies(u *url.URL, cookies []*Cookie) {
+	j.logf("SetCookie(%q, %v)\n", u, cookies)
+}
+
+func (j *RecordingJar) Cookies(u *url.URL) []*Cookie {
+	j.logf("Cookies(%q)\n", u)
+	return nil
+}
+
+func (j *RecordingJar) logf(format string, args ...interface{}) {
+	j.mu.Lock()
+	defer j.mu.Unlock()
+	fmt.Fprintf(&j.log, format, args...)
+}
+
 func TestStreamingGet(t *testing.T) {
 	say := make(chan string)
 	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
diff --git a/libgo/go/net/http/pprof/pprof.go b/libgo/go/net/http/pprof/pprof.go
index d70bf4e..0c03e5b 100644
--- a/libgo/go/net/http/pprof/pprof.go
+++ b/libgo/go/net/http/pprof/pprof.go
@@ -34,9 +34,8 @@
 //
 //	go tool pprof http://localhost:6060/debug/pprof/block
 //
-// Or to view all available profiles:
-//
-//	go tool pprof http://localhost:6060/debug/pprof/
+// To view all available profiles, open http://localhost:6060/debug/pprof/
+// in your browser.
 //
 // For a study of the facility in action, visit
 //
diff --git a/libgo/go/net/http/readrequest_test.go b/libgo/go/net/http/readrequest_test.go
index 2e03c65..ffdd6a8 100644
--- a/libgo/go/net/http/readrequest_test.go
+++ b/libgo/go/net/http/readrequest_test.go
@@ -247,6 +247,54 @@ var reqTests = []reqTest{
 		noTrailer,
 		noError,
 	},
+
+	// SSDP Notify request. golang.org/issue/3692
+	{
+		"NOTIFY * HTTP/1.1\r\nServer: foo\r\n\r\n",
+		&Request{
+			Method: "NOTIFY",
+			URL: &url.URL{
+				Path: "*",
+			},
+			Proto:      "HTTP/1.1",
+			ProtoMajor: 1,
+			ProtoMinor: 1,
+			Header: Header{
+				"Server": []string{"foo"},
+			},
+			Close:         false,
+			ContentLength: 0,
+			RequestURI:    "*",
+		},
+
+		noBody,
+		noTrailer,
+		noError,
+	},
+
+	// OPTIONS request. Similar to golang.org/issue/3692
+	{
+		"OPTIONS * HTTP/1.1\r\nServer: foo\r\n\r\n",
+		&Request{
+			Method: "OPTIONS",
+			URL: &url.URL{
+				Path: "*",
+			},
+			Proto:      "HTTP/1.1",
+			ProtoMajor: 1,
+			ProtoMinor: 1,
+			Header: Header{
+				"Server": []string{"foo"},
+			},
+			Close:         false,
+			ContentLength: 0,
+			RequestURI:    "*",
+		},
+
+		noBody,
+		noTrailer,
+		noError,
+	},
 }
 
 func TestReadRequest(t *testing.T) {
diff --git a/libgo/go/net/http/serve_test.go b/libgo/go/net/http/serve_test.go
index 8ca227f..1de4171 100644
--- a/libgo/go/net/http/serve_test.go
+++ b/libgo/go/net/http/serve_test.go
@@ -918,15 +918,19 @@ func TestZeroLengthPostAndResponse(t *testing.T) {
 	}
 }
 
+func TestHandlerPanicNil(t *testing.T) {
+	testHandlerPanic(t, false, nil)
+}
+
 func TestHandlerPanic(t *testing.T) {
-	testHandlerPanic(t, false)
+	testHandlerPanic(t, false, "intentional death for testing")
 }
 
 func TestHandlerPanicWithHijack(t *testing.T) {
-	testHandlerPanic(t, true)
+	testHandlerPanic(t, true, "intentional death for testing")
 }
 
-func testHandlerPanic(t *testing.T, withHijack bool) {
+func testHandlerPanic(t *testing.T, withHijack bool, panicValue interface{}) {
 	// Unlike the other tests that set the log output to ioutil.Discard
 	// to quiet the output, this test uses a pipe.  The pipe serves three
 	// purposes:
@@ -955,7 +959,7 @@ func testHandlerPanic(t *testing.T, withHijack bool) {
 			}
 			defer rwc.Close()
 		}
-		panic("intentional death for testing")
+		panic(panicValue)
 	}))
 	defer ts.Close()
 
@@ -968,7 +972,7 @@ func testHandlerPanic(t *testing.T, withHijack bool) {
 		_, err := pr.Read(buf)
 		pr.Close()
 		if err != nil {
-			t.Fatal(err)
+			t.Error(err)
 		}
 		done <- true
 	}()
@@ -978,6 +982,10 @@ func testHandlerPanic(t *testing.T, withHijack bool) {
 		t.Logf("expected an error")
 	}
 
+	if panicValue == nil {
+		return
+	}
+
 	select {
 	case <-done:
 		return
@@ -1288,6 +1296,58 @@ For:
 	ts.Close()
 }
 
+func TestOptions(t *testing.T) {
+	uric := make(chan string, 2) // only expect 1, but leave space for 2
+	mux := NewServeMux()
+	mux.HandleFunc("/", func(w ResponseWriter, r *Request) {
+		uric <- r.RequestURI
+	})
+	ts := httptest.NewServer(mux)
+	defer ts.Close()
+
+	conn, err := net.Dial("tcp", ts.Listener.Addr().String())
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer conn.Close()
+
+	// An OPTIONS * request should succeed.
+	_, err = conn.Write([]byte("OPTIONS * HTTP/1.1\r\nHost: foo.com\r\n\r\n"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	br := bufio.NewReader(conn)
+	res, err := ReadResponse(br, &Request{Method: "OPTIONS"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.StatusCode != 200 {
+		t.Errorf("Got non-200 response to OPTIONS *: %#v", res)
+	}
+
+	// A GET * request on a ServeMux should fail.
+	_, err = conn.Write([]byte("GET * HTTP/1.1\r\nHost: foo.com\r\n\r\n"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	res, err = ReadResponse(br, &Request{Method: "GET"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.StatusCode != 400 {
+		t.Errorf("Got non-400 response to GET *: %#v", res)
+	}
+
+	res, err = Get(ts.URL + "/second")
+	if err != nil {
+		t.Fatal(err)
+	}
+	res.Body.Close()
+	if got := <-uric; got != "/second" {
+		t.Errorf("Handler saw request for %q; want /second", got)
+	}
+}
+
 // goTimeout runs f, failing t if f takes more than ns to complete.
 func goTimeout(t *testing.T, d time.Duration, f func()) {
 	ch := make(chan bool, 2)
diff --git a/libgo/go/net/http/server.go b/libgo/go/net/http/server.go
index c4ddbec..89a46f0 100644
--- a/libgo/go/net/http/server.go
+++ b/libgo/go/net/http/server.go
@@ -702,24 +702,19 @@ func (c *conn) closeWriteAndWait() {
 // Serve a new connection.
 func (c *conn) serve() {
 	defer func() {
-		err := recover()
-		if err == nil {
-			return
+		if err := recover(); err != nil {
+			const size = 4096
+			buf := make([]byte, size)
+			buf = buf[:runtime.Stack(buf, false)]
+			log.Printf("http: panic serving %v: %v\n%s", c.remoteAddr, err, buf)
 		}
-
-		const size = 4096
-		buf := make([]byte, size)
-		buf = buf[:runtime.Stack(buf, false)]
-		log.Printf("http: panic serving %v: %v\n%s", c.remoteAddr, err, buf)
-
-		if c.rwc != nil { // may be nil if connection hijacked
-			c.rwc.Close()
+		if !c.hijacked() {
+			c.close()
 		}
 	}()
 
 	if tlsConn, ok := c.rwc.(*tls.Conn); ok {
 		if err := tlsConn.Handshake(); err != nil {
-			c.close()
 			return
 		}
 		c.tlsState = new(tls.ConnectionState)
@@ -770,6 +765,9 @@ func (c *conn) serve() {
 		if handler == nil {
 			handler = DefaultServeMux
 		}
+		if req.RequestURI == "*" && req.Method == "OPTIONS" {
+			handler = globalOptionsHandler{}
+		}
 
 		// HTTP cannot have multiple simultaneous active requests.[*]
 		// Until the server replies to this request, it can't read another,
@@ -788,7 +786,6 @@ func (c *conn) serve() {
 			break
 		}
 	}
-	c.close()
 }
 
 func (w *response) sendExpectationFailed() {
@@ -1085,6 +1082,11 @@ func (mux *ServeMux) handler(host, path string) (h Handler, pattern string) {
 // ServeHTTP dispatches the request to the handler whose
 // pattern most closely matches the request URL.
 func (mux *ServeMux) ServeHTTP(w ResponseWriter, r *Request) {
+	if r.RequestURI == "*" {
+		w.Header().Set("Connection", "close")
+		w.WriteHeader(StatusBadRequest)
+		return
+	}
 	h, _ := mux.Handler(r)
 	h.ServeHTTP(w, r)
 }
@@ -1408,6 +1410,22 @@ func (tw *timeoutWriter) WriteHeader(code int) {
 	tw.w.WriteHeader(code)
 }
 
+// globalOptionsHandler responds to "OPTIONS *" requests.
+type globalOptionsHandler struct{}
+
+func (globalOptionsHandler) ServeHTTP(w ResponseWriter, r *Request) {
+	w.Header().Set("Content-Length", "0")
+	if r.ContentLength != 0 {
+		// Read up to 4KB of OPTIONS body (as mentioned in the
+		// spec as being reserved for future use), but anything
+		// over that is considered a waste of server resources
+		// (or an attack) and we abort and close the connection,
+		// courtesy of MaxBytesReader's EOF behavior.
+		mb := MaxBytesReader(w, r.Body, 4<<10)
+		io.Copy(ioutil.Discard, mb)
+	}
+}
+
 // loggingConn is used for debugging.
 type loggingConn struct {
 	name string
diff --git a/libgo/go/net/http/transport.go b/libgo/go/net/http/transport.go
index 7b4afeb..d0505bf 100644
--- a/libgo/go/net/http/transport.go
+++ b/libgo/go/net/http/transport.go
@@ -144,6 +144,9 @@ func (t *Transport) RoundTrip(req *Request) (resp *Response, err error) {
 		}
 		return rt.RoundTrip(req)
 	}
+	if req.URL.Host == "" {
+		return nil, errors.New("http: no Host in request URL")
+	}
 	treq := &transportRequest{Request: req}
 	cm, err := t.connectMethodForRequest(treq)
 	if err != nil {
@@ -739,6 +742,7 @@ WaitResponse:
 		case err := <-writeErrCh:
 			if err != nil {
 				re = responseAndError{nil, err}
+				pc.close()
 				break WaitResponse
 			}
 		case <-pconnDeadCh:
diff --git a/libgo/go/net/http/transport_test.go b/libgo/go/net/http/transport_test.go
index f1d4158..c37ef13 100644
--- a/libgo/go/net/http/transport_test.go
+++ b/libgo/go/net/http/transport_test.go
@@ -778,6 +778,45 @@ func TestTransportPersistConnLeak(t *testing.T) {
 	}
 }
 
+// golang.org/issue/4531: Transport leaks goroutines when
+// request.ContentLength is explicitly short
+func TestTransportPersistConnLeakShortBody(t *testing.T) {
+	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
+	}))
+	defer ts.Close()
+
+	tr := &Transport{}
+	c := &Client{Transport: tr}
+
+	n0 := runtime.NumGoroutine()
+	body := []byte("Hello")
+	for i := 0; i < 20; i++ {
+		req, err := NewRequest("POST", ts.URL, bytes.NewReader(body))
+		if err != nil {
+			t.Fatal(err)
+		}
+		req.ContentLength = int64(len(body) - 2) // explicitly short
+		_, err = c.Do(req)
+		if err == nil {
+			t.Fatal("Expect an error from writing too long of a body.")
+		}
+	}
+	nhigh := runtime.NumGoroutine()
+	tr.CloseIdleConnections()
+	time.Sleep(50 * time.Millisecond)
+	runtime.GC()
+	nfinal := runtime.NumGoroutine()
+
+	growth := nfinal - n0
+
+	// We expect 0 or 1 extra goroutine, empirically.  Allow up to 5.
+	// Previously we were leaking one per numReq.
+	t.Logf("goroutine growth: %d -> %d -> %d (delta: %d)", n0, nhigh, nfinal, growth)
+	if int(growth) > 5 {
+		t.Error("too many new goroutines")
+	}
+}
+
 // This used to crash; http://golang.org/issue/3266
 func TestTransportIdleConnCrash(t *testing.T) {
 	tr := &Transport{}
@@ -1062,6 +1101,20 @@ func TestTransportAltProto(t *testing.T) {
 	}
 }
 
+func TestTransportNoHost(t *testing.T) {
+	tr := &Transport{}
+	_, err := tr.RoundTrip(&Request{
+		Header: make(Header),
+		URL: &url.URL{
+			Scheme: "http",
+		},
+	})
+	want := "http: no Host in request URL"
+	if got := fmt.Sprint(err); got != want {
+		t.Errorf("error = %v; want %q", err, want)
+	}
+}
+
 var proxyFromEnvTests = []struct {
 	env     string
 	wanturl string
diff --git a/libgo/go/net/packetconn_test.go b/libgo/go/net/packetconn_test.go
index 5075baa..ff29e24 100644
--- a/libgo/go/net/packetconn_test.go
+++ b/libgo/go/net/packetconn_test.go
@@ -24,6 +24,15 @@ var packetConnTests = []struct {
 }
 
 func TestPacketConn(t *testing.T) {
+	closer := func(c net.PacketConn, net, addr1, addr2 string) {
+		c.Close()
+		switch net {
+		case "unixgram":
+			os.Remove(addr1)
+			os.Remove(addr2)
+		}
+	}
+
 	for _, tt := range packetConnTests {
 		var wb []byte
 		netstr := strings.Split(tt.net, ":")
@@ -39,7 +48,7 @@ func TestPacketConn(t *testing.T) {
 				continue
 			}
 			id := os.Getpid() & 0xffff
-			wb = newICMPEchoRequest(id, 1, 128, []byte("IP PACKETCONN TEST "))
+			wb = newICMPEchoRequest(id, 1, 128, []byte("IP PACKETCONN TEST"))
 		case "unixgram":
 			switch runtime.GOOS {
 			case "plan9", "windows":
@@ -60,7 +69,7 @@ func TestPacketConn(t *testing.T) {
 		c1.SetDeadline(time.Now().Add(100 * time.Millisecond))
 		c1.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
 		c1.SetWriteDeadline(time.Now().Add(100 * time.Millisecond))
-		defer c1.Close()
+		defer closer(c1, netstr[0], tt.addr1, tt.addr2)
 
 		c2, err := net.ListenPacket(tt.net, tt.addr2)
 		if err != nil {
@@ -70,7 +79,7 @@ func TestPacketConn(t *testing.T) {
 		c2.SetDeadline(time.Now().Add(100 * time.Millisecond))
 		c2.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
 		c2.SetWriteDeadline(time.Now().Add(100 * time.Millisecond))
-		defer c2.Close()
+		defer closer(c2, netstr[0], tt.addr1, tt.addr2)
 
 		if _, err := c1.WriteTo(wb, c2.LocalAddr()); err != nil {
 			t.Fatalf("net.PacketConn.WriteTo failed: %v", err)
@@ -86,12 +95,6 @@ func TestPacketConn(t *testing.T) {
 		if _, _, err := c1.ReadFrom(rb1); err != nil {
 			t.Fatalf("net.PacketConn.ReadFrom failed: %v", err)
 		}
-
-		switch netstr[0] {
-		case "unixgram":
-			os.Remove(tt.addr1)
-			os.Remove(tt.addr2)
-		}
 	}
 }
 
diff --git a/libgo/go/net/protoconn_test.go b/libgo/go/net/protoconn_test.go
index f249372..d99de3f 100644
--- a/libgo/go/net/protoconn_test.go
+++ b/libgo/go/net/protoconn_test.go
@@ -263,9 +263,10 @@ func TestUnixConnSpecificMethods(t *testing.T) {
 		return
 	}
 
-	p1, p2 := "/tmp/gotest.net1", "/tmp/gotest.net2"
+	p1, p2, p3 := "/tmp/gotest.net1", "/tmp/gotest.net2", "/tmp/gotest.net3"
 	os.Remove(p1)
 	os.Remove(p2)
+	os.Remove(p3)
 
 	a1, err := net.ResolveUnixAddr("unixgram", p1)
 	if err != nil {
@@ -305,9 +306,30 @@ func TestUnixConnSpecificMethods(t *testing.T) {
 	defer c2.Close()
 	defer os.Remove(p2)
 
+	a3, err := net.ResolveUnixAddr("unixgram", p3)
+	if err != nil {
+		t.Errorf("net.ResolveUnixAddr failed: %v", err)
+		return
+	}
+	c3, err := net.ListenUnixgram("unixgram", a3)
+	if err != nil {
+		t.Errorf("net.ListenUnixgram failed: %v", err)
+		return
+	}
+	c3.LocalAddr()
+	c3.RemoteAddr()
+	c3.SetDeadline(time.Now().Add(100 * time.Millisecond))
+	c3.SetReadDeadline(time.Now().Add(100 * time.Millisecond))
+	c3.SetWriteDeadline(time.Now().Add(100 * time.Millisecond))
+	c3.SetReadBuffer(2048)
+	c3.SetWriteBuffer(2048)
+	defer c3.Close()
+	defer os.Remove(p3)
+
 	wb := []byte("UNIXCONN TEST")
 	rb1 := make([]byte, 128)
 	rb2 := make([]byte, 128)
+	rb3 := make([]byte, 128)
 	if _, _, err := c1.WriteMsgUnix(wb, nil, a2); err != nil {
 		t.Errorf("net.UnixConn.WriteMsgUnix failed: %v", err)
 		return
@@ -324,9 +346,22 @@ func TestUnixConnSpecificMethods(t *testing.T) {
 		t.Errorf("net.UnixConn.ReadFromUnix failed: %v", err)
 		return
 	}
-
-	// TODO: http://golang.org/issue/3875
-	net.ListenUnixgram("unixgram", nil)
+	if _, err := c3.WriteToUnix(wb, a1); err != nil {
+		t.Errorf("net.UnixConn.WriteToUnix failed: %v", err)
+		return
+	}
+	if _, _, err := c1.ReadFromUnix(rb1); err != nil {
+		t.Errorf("net.UnixConn.ReadFromUnix failed: %v", err)
+		return
+	}
+	if _, err := c2.WriteToUnix(wb, a3); err != nil {
+		t.Errorf("net.UnixConn.WriteToUnix failed: %v", err)
+		return
+	}
+	if _, _, err := c3.ReadFromUnix(rb3); err != nil {
+		t.Errorf("net.UnixConn.ReadFromUnix failed: %v", err)
+		return
+	}
 
 	if f, err := c1.File(); err != nil {
 		t.Errorf("net.UnixConn.File failed: %v", err)
diff --git a/libgo/go/net/smtp/smtp.go b/libgo/go/net/smtp/smtp.go
index 59f6449..4b91778 100644
--- a/libgo/go/net/smtp/smtp.go
+++ b/libgo/go/net/smtp/smtp.go
@@ -13,6 +13,7 @@ package smtp
 import (
 	"crypto/tls"
 	"encoding/base64"
+	"errors"
 	"io"
 	"net"
 	"net/textproto"
@@ -33,7 +34,10 @@ type Client struct {
 	// map of supported extensions
 	ext map[string]string
 	// supported auth mechanisms
-	auth []string
+	auth       []string
+	localName  string // the name to use in HELO/EHLO
+	didHello   bool   // whether we've said HELO/EHLO
+	helloError error  // the error from the hello
 }
 
 // Dial returns a new Client connected to an SMTP server at addr.
@@ -55,12 +59,33 @@ func NewClient(conn net.Conn, host string) (*Client, error) {
 		text.Close()
 		return nil, err
 	}
-	c := &Client{Text: text, conn: conn, serverName: host}
-	err = c.ehlo()
-	if err != nil {
-		err = c.helo()
+	c := &Client{Text: text, conn: conn, serverName: host, localName: "localhost"}
+	return c, nil
+}
+
+// hello runs a hello exchange if needed.
+func (c *Client) hello() error {
+	if !c.didHello {
+		c.didHello = true
+		err := c.ehlo()
+		if err != nil {
+			c.helloError = c.helo()
+		}
+	}
+	return c.helloError
+}
+
+// Hello sends a HELO or EHLO to the server as the given host name.
+// Calling this method is only necessary if the client needs control
+// over the host name used.  The client will introduce itself as "localhost"
+// automatically otherwise.  If Hello is called, it must be called before
+// any of the other methods.
+func (c *Client) Hello(localName string) error {
+	if c.didHello {
+		return errors.New("smtp: Hello called after other methods")
 	}
-	return c, err
+	c.localName = localName
+	return c.hello()
 }
 
 // cmd is a convenience function that sends a command and returns the response
@@ -79,14 +104,14 @@ func (c *Client) cmd(expectCode int, format string, args ...interface{}) (int, s
 // server does not support ehlo.
 func (c *Client) helo() error {
 	c.ext = nil
-	_, _, err := c.cmd(250, "HELO localhost")
+	_, _, err := c.cmd(250, "HELO %s", c.localName)
 	return err
 }
 
 // ehlo sends the EHLO (extended hello) greeting to the server. It
 // should be the preferred greeting for servers that support it.
 func (c *Client) ehlo() error {
-	_, msg, err := c.cmd(250, "EHLO localhost")
+	_, msg, err := c.cmd(250, "EHLO %s", c.localName)
 	if err != nil {
 		return err
 	}
@@ -113,6 +138,9 @@ func (c *Client) ehlo() error {
 // StartTLS sends the STARTTLS command and encrypts all further communication.
 // Only servers that advertise the STARTTLS extension support this function.
 func (c *Client) StartTLS(config *tls.Config) error {
+	if err := c.hello(); err != nil {
+		return err
+	}
 	_, _, err := c.cmd(220, "STARTTLS")
 	if err != nil {
 		return err
@@ -128,6 +156,9 @@ func (c *Client) StartTLS(config *tls.Config) error {
 // does not necessarily indicate an invalid address. Many servers
 // will not verify addresses for security reasons.
 func (c *Client) Verify(addr string) error {
+	if err := c.hello(); err != nil {
+		return err
+	}
 	_, _, err := c.cmd(250, "VRFY %s", addr)
 	return err
 }
@@ -136,6 +167,9 @@ func (c *Client) Verify(addr string) error {
 // A failed authentication closes the connection.
 // Only servers that advertise the AUTH extension support this function.
 func (c *Client) Auth(a Auth) error {
+	if err := c.hello(); err != nil {
+		return err
+	}
 	encoding := base64.StdEncoding
 	mech, resp, err := a.Start(&ServerInfo{c.serverName, c.tls, c.auth})
 	if err != nil {
@@ -178,6 +212,9 @@ func (c *Client) Auth(a Auth) error {
 // parameter.
 // This initiates a mail transaction and is followed by one or more Rcpt calls.
 func (c *Client) Mail(from string) error {
+	if err := c.hello(); err != nil {
+		return err
+	}
 	cmdStr := "MAIL FROM:<%s>"
 	if c.ext != nil {
 		if _, ok := c.ext["8BITMIME"]; ok {
@@ -227,6 +264,9 @@ func SendMail(addr string, a Auth, from string, to []string, msg []byte) error {
 	if err != nil {
 		return err
 	}
+	if err := c.hello(); err != nil {
+		return err
+	}
 	if ok, _ := c.Extension("STARTTLS"); ok {
 		if err = c.StartTLS(nil); err != nil {
 			return err
@@ -267,6 +307,9 @@ func SendMail(addr string, a Auth, from string, to []string, msg []byte) error {
 // Extension also returns a string that contains any parameters the
 // server specifies for the extension.
 func (c *Client) Extension(ext string) (bool, string) {
+	if err := c.hello(); err != nil {
+		return false, ""
+	}
 	if c.ext == nil {
 		return false, ""
 	}
@@ -278,12 +321,18 @@ func (c *Client) Extension(ext string) (bool, string) {
 // Reset sends the RSET command to the server, aborting the current mail
 // transaction.
 func (c *Client) Reset() error {
+	if err := c.hello(); err != nil {
+		return err
+	}
 	_, _, err := c.cmd(250, "RSET")
 	return err
 }
 
 // Quit sends the QUIT command and closes the connection to the server.
 func (c *Client) Quit() error {
+	if err := c.hello(); err != nil {
+		return err
+	}
 	_, _, err := c.cmd(221, "QUIT")
 	if err != nil {
 		return err
diff --git a/libgo/go/net/smtp/smtp_test.go b/libgo/go/net/smtp/smtp_test.go
index c315d18..8317428 100644
--- a/libgo/go/net/smtp/smtp_test.go
+++ b/libgo/go/net/smtp/smtp_test.go
@@ -69,14 +69,14 @@ func (f faker) SetReadDeadline(time.Time) error  { return nil }
 func (f faker) SetWriteDeadline(time.Time) error { return nil }
 
 func TestBasic(t *testing.T) {
-	basicServer = strings.Join(strings.Split(basicServer, "\n"), "\r\n")
-	basicClient = strings.Join(strings.Split(basicClient, "\n"), "\r\n")
+	server := strings.Join(strings.Split(basicServer, "\n"), "\r\n")
+	client := strings.Join(strings.Split(basicClient, "\n"), "\r\n")
 
 	var cmdbuf bytes.Buffer
 	bcmdbuf := bufio.NewWriter(&cmdbuf)
 	var fake faker
-	fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(basicServer)), bcmdbuf)
-	c := &Client{Text: textproto.NewConn(fake)}
+	fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(server)), bcmdbuf)
+	c := &Client{Text: textproto.NewConn(fake), localName: "localhost"}
 
 	if err := c.helo(); err != nil {
 		t.Fatalf("HELO failed: %s", err)
@@ -88,6 +88,7 @@ func TestBasic(t *testing.T) {
 		t.Fatalf("Second EHLO failed: %s", err)
 	}
 
+	c.didHello = true
 	if ok, args := c.Extension("aUtH"); !ok || args != "LOGIN PLAIN" {
 		t.Fatalf("Expected AUTH supported")
 	}
@@ -143,8 +144,8 @@ Goodbye.`
 
 	bcmdbuf.Flush()
 	actualcmds := cmdbuf.String()
-	if basicClient != actualcmds {
-		t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, basicClient)
+	if client != actualcmds {
+		t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, client)
 	}
 }
 
@@ -187,8 +188,8 @@ QUIT
 `
 
 func TestNewClient(t *testing.T) {
-	newClientServer = strings.Join(strings.Split(newClientServer, "\n"), "\r\n")
-	newClientClient = strings.Join(strings.Split(newClientClient, "\n"), "\r\n")
+	server := strings.Join(strings.Split(newClientServer, "\n"), "\r\n")
+	client := strings.Join(strings.Split(newClientClient, "\n"), "\r\n")
 
 	var cmdbuf bytes.Buffer
 	bcmdbuf := bufio.NewWriter(&cmdbuf)
@@ -197,7 +198,7 @@ func TestNewClient(t *testing.T) {
 		return cmdbuf.String()
 	}
 	var fake faker
-	fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(newClientServer)), bcmdbuf)
+	fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(server)), bcmdbuf)
 	c, err := NewClient(fake, "fake.host")
 	if err != nil {
 		t.Fatalf("NewClient: %v\n(after %v)", err, out())
@@ -213,8 +214,8 @@ func TestNewClient(t *testing.T) {
 	}
 
 	actualcmds := out()
-	if newClientClient != actualcmds {
-		t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, newClientClient)
+	if client != actualcmds {
+		t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, client)
 	}
 }
 
@@ -231,13 +232,13 @@ QUIT
 `
 
 func TestNewClient2(t *testing.T) {
-	newClient2Server = strings.Join(strings.Split(newClient2Server, "\n"), "\r\n")
-	newClient2Client = strings.Join(strings.Split(newClient2Client, "\n"), "\r\n")
+	server := strings.Join(strings.Split(newClient2Server, "\n"), "\r\n")
+	client := strings.Join(strings.Split(newClient2Client, "\n"), "\r\n")
 
 	var cmdbuf bytes.Buffer
 	bcmdbuf := bufio.NewWriter(&cmdbuf)
 	var fake faker
-	fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(newClient2Server)), bcmdbuf)
+	fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(server)), bcmdbuf)
 	c, err := NewClient(fake, "fake.host")
 	if err != nil {
 		t.Fatalf("NewClient: %v", err)
@@ -251,8 +252,8 @@ func TestNewClient2(t *testing.T) {
 
 	bcmdbuf.Flush()
 	actualcmds := cmdbuf.String()
-	if newClient2Client != actualcmds {
-		t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, newClient2Client)
+	if client != actualcmds {
+		t.Fatalf("Got:\n%s\nExpected:\n%s", actualcmds, client)
 	}
 }
 
@@ -269,3 +270,199 @@ var newClient2Client = `EHLO localhost
 HELO localhost
 QUIT
 `
+
+func TestHello(t *testing.T) {
+
+	if len(helloServer) != len(helloClient) {
+		t.Fatalf("Hello server and client size mismatch")
+	}
+
+	for i := 0; i < len(helloServer); i++ {
+		server := strings.Join(strings.Split(baseHelloServer+helloServer[i], "\n"), "\r\n")
+		client := strings.Join(strings.Split(baseHelloClient+helloClient[i], "\n"), "\r\n")
+		var cmdbuf bytes.Buffer
+		bcmdbuf := bufio.NewWriter(&cmdbuf)
+		var fake faker
+		fake.ReadWriter = bufio.NewReadWriter(bufio.NewReader(strings.NewReader(server)), bcmdbuf)
+		c, err := NewClient(fake, "fake.host")
+		if err != nil {
+			t.Fatalf("NewClient: %v", err)
+		}
+		c.localName = "customhost"
+		err = nil
+
+		switch i {
+		case 0:
+			err = c.Hello("customhost")
+		case 1:
+			err = c.StartTLS(nil)
+			if err.Error() == "502 Not implemented" {
+				err = nil
+			}
+		case 2:
+			err = c.Verify("test@example.com")
+		case 3:
+			c.tls = true
+			c.serverName = "smtp.google.com"
+			err = c.Auth(PlainAuth("", "user", "pass", "smtp.google.com"))
+		case 4:
+			err = c.Mail("test@example.com")
+		case 5:
+			ok, _ := c.Extension("feature")
+			if ok {
+				t.Errorf("Expected FEATURE not to be supported")
+			}
+		case 6:
+			err = c.Reset()
+		case 7:
+			err = c.Quit()
+		case 8:
+			err = c.Verify("test@example.com")
+			if err != nil {
+				err = c.Hello("customhost")
+				if err != nil {
+					t.Errorf("Want error, got none")
+				}
+			}
+		default:
+			t.Fatalf("Unhandled command")
+		}
+
+		if err != nil {
+			t.Errorf("Command %d failed: %v", i, err)
+		}
+
+		bcmdbuf.Flush()
+		actualcmds := cmdbuf.String()
+		if client != actualcmds {
+			t.Errorf("Got:\n%s\nExpected:\n%s", actualcmds, client)
+		}
+	}
+}
+
+var baseHelloServer = `220 hello world
+502 EH?
+250-mx.google.com at your service
+250 FEATURE
+`
+
+var helloServer = []string{
+	"",
+	"502 Not implemented\n",
+	"250 User is valid\n",
+	"235 Accepted\n",
+	"250 Sender ok\n",
+	"",
+	"250 Reset ok\n",
+	"221 Goodbye\n",
+	"250 Sender ok\n",
+}
+
+var baseHelloClient = `EHLO customhost
+HELO customhost
+`
+
+var helloClient = []string{
+	"",
+	"STARTTLS\n",
+	"VRFY test@example.com\n",
+	"AUTH PLAIN AHVzZXIAcGFzcw==\n",
+	"MAIL FROM:<test@example.com>\n",
+	"",
+	"RSET\n",
+	"QUIT\n",
+	"VRFY test@example.com\n",
+}
+
+func TestSendMail(t *testing.T) {
+	server := strings.Join(strings.Split(sendMailServer, "\n"), "\r\n")
+	client := strings.Join(strings.Split(sendMailClient, "\n"), "\r\n")
+	var cmdbuf bytes.Buffer
+	bcmdbuf := bufio.NewWriter(&cmdbuf)
+	l, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("Unable to to create listener: %v", err)
+	}
+	defer l.Close()
+
+	// prevent data race on bcmdbuf
+	var done = make(chan struct{})
+	go func(data []string) {
+
+		defer close(done)
+
+		conn, err := l.Accept()
+		if err != nil {
+			t.Errorf("Accept error: %v", err)
+			return
+		}
+		defer conn.Close()
+
+		tc := textproto.NewConn(conn)
+		for i := 0; i < len(data) && data[i] != ""; i++ {
+			tc.PrintfLine(data[i])
+			for len(data[i]) >= 4 && data[i][3] == '-' {
+				i++
+				tc.PrintfLine(data[i])
+			}
+			if data[i] == "221 Goodbye" {
+				return
+			}
+			read := false
+			for !read || data[i] == "354 Go ahead" {
+				msg, err := tc.ReadLine()
+				bcmdbuf.Write([]byte(msg + "\r\n"))
+				read = true
+				if err != nil {
+					t.Errorf("Read error: %v", err)
+					return
+				}
+				if data[i] == "354 Go ahead" && msg == "." {
+					break
+				}
+			}
+		}
+	}(strings.Split(server, "\r\n"))
+
+	err = SendMail(l.Addr().String(), nil, "test@example.com", []string{"other@example.com"}, []byte(strings.Replace(`From: test@example.com
+To: other@example.com
+Subject: SendMail test
+
+SendMail is working for me.
+`, "\n", "\r\n", -1)))
+
+	if err != nil {
+		t.Errorf("%v", err)
+	}
+
+	<-done
+	bcmdbuf.Flush()
+	actualcmds := cmdbuf.String()
+	if client != actualcmds {
+		t.Errorf("Got:\n%s\nExpected:\n%s", actualcmds, client)
+	}
+}
+
+var sendMailServer = `220 hello world
+502 EH?
+250 mx.google.com at your service
+250 Sender ok
+250 Receiver ok
+354 Go ahead
+250 Data ok
+221 Goodbye
+`
+
+var sendMailClient = `EHLO localhost
+HELO localhost
+MAIL FROM:<test@example.com>
+RCPT TO:<other@example.com>
+DATA
+From: test@example.com
+To: other@example.com
+Subject: SendMail test
+
+SendMail is working for me.
+.
+QUIT
+`
diff --git a/libgo/go/net/unixsock_plan9.go b/libgo/go/net/unixsock_plan9.go
index f7be5d2..713820c 100644
--- a/libgo/go/net/unixsock_plan9.go
+++ b/libgo/go/net/unixsock_plan9.go
@@ -64,21 +64,21 @@ func (c *UnixConn) WriteMsgUnix(b, oob []byte, addr *UnixAddr) (n, oobn int, err
 	return 0, 0, syscall.EPLAN9
 }
 
-// CloseRead shuts down the reading side of the Unix domain
-// connection.  Most callers should just use Close.
+// CloseRead shuts down the reading side of the Unix domain connection.
+// Most callers should just use Close.
 func (c *UnixConn) CloseRead() error {
 	return syscall.EPLAN9
 }
 
-// CloseWrite shuts down the writing side of the Unix domain
-// connection.  Most callers should just use Close.
+// CloseWrite shuts down the writing side of the Unix domain connection.
+// Most callers should just use Close.
 func (c *UnixConn) CloseWrite() error {
 	return syscall.EPLAN9
 }
 
 // DialUnix connects to the remote address raddr on the network net,
-// which must be "unix" or "unixgram".  If laddr is not nil, it is
-// used as the local address for the connection.
+// which must be "unix", "unixgram" or "unixpacket".  If laddr is not
+// nil, it is used as the local address for the connection.
 func DialUnix(net string, laddr, raddr *UnixAddr) (*UnixConn, error) {
 	return dialUnix(net, laddr, raddr, noDeadline)
 }
@@ -93,7 +93,8 @@ func dialUnix(net string, laddr, raddr *UnixAddr, deadline time.Time) (*UnixConn
 type UnixListener struct{}
 
 // ListenUnix announces on the Unix domain socket laddr and returns a
-// Unix listener.  Net must be "unix" (stream sockets).
+// Unix listener.  The network net must be "unix", "unixgram" or
+// "unixpacket".
 func ListenUnix(net string, laddr *UnixAddr) (*UnixListener, error) {
 	return nil, syscall.EPLAN9
 }
@@ -134,8 +135,8 @@ func (l *UnixListener) File() (*os.File, error) {
 
 // ListenUnixgram listens for incoming Unix datagram packets addressed
 // to the local address laddr.  The returned connection c's ReadFrom
-// and WriteTo methods can be used to receive and send UDP packets
-// with per-packet addressing.  The network net must be "unixgram".
-func ListenUnixgram(net string, laddr *UnixAddr) (*UDPConn, error) {
+// and WriteTo methods can be used to receive and send packets with
+// per-packet addressing.  The network net must be "unixgram".
+func ListenUnixgram(net string, laddr *UnixAddr) (*UnixConn, error) {
 	return nil, syscall.EPLAN9
 }
diff --git a/libgo/go/net/unixsock_posix.go b/libgo/go/net/unixsock_posix.go
index 16ebd58..653190c 100644
--- a/libgo/go/net/unixsock_posix.go
+++ b/libgo/go/net/unixsock_posix.go
@@ -9,29 +9,27 @@
 package net
 
 import (
+	"errors"
 	"os"
 	"syscall"
 	"time"
 )
 
-func unixSocket(net string, laddr, raddr *UnixAddr, mode string, deadline time.Time) (fd *netFD, err error) {
+func unixSocket(net string, laddr, raddr *UnixAddr, mode string, deadline time.Time) (*netFD, error) {
 	var sotype int
 	switch net {
-	default:
-		return nil, UnknownNetworkError(net)
 	case "unix":
 		sotype = syscall.SOCK_STREAM
 	case "unixgram":
 		sotype = syscall.SOCK_DGRAM
 	case "unixpacket":
 		sotype = syscall.SOCK_SEQPACKET
+	default:
+		return nil, UnknownNetworkError(net)
 	}
 
 	var la, ra syscall.Sockaddr
 	switch mode {
-	default:
-		panic("unixSocket mode " + mode)
-
 	case "dial":
 		if laddr != nil {
 			la = &syscall.SockaddrUnix{Name: laddr.Name}
@@ -41,15 +39,10 @@ func unixSocket(net string, laddr, raddr *UnixAddr, mode string, deadline time.T
 		} else if sotype != syscall.SOCK_DGRAM || laddr == nil {
 			return nil, &OpError{Op: mode, Net: net, Err: errMissingAddress}
 		}
-
 	case "listen":
-		if laddr == nil {
-			return nil, &OpError{mode, net, nil, errMissingAddress}
-		}
 		la = &syscall.SockaddrUnix{Name: laddr.Name}
-		if raddr != nil {
-			return nil, &OpError{Op: mode, Net: net, Addr: raddr, Err: &AddrError{Err: "unexpected remote address", Addr: raddr.String()}}
-		}
+	default:
+		return nil, errors.New("unknown mode: " + mode)
 	}
 
 	f := sockaddrToUnix
@@ -59,15 +52,16 @@ func unixSocket(net string, laddr, raddr *UnixAddr, mode string, deadline time.T
 		f = sockaddrToUnixpacket
 	}
 
-	fd, err = socket(net, syscall.AF_UNIX, sotype, 0, false, la, ra, deadline, f)
+	fd, err := socket(net, syscall.AF_UNIX, sotype, 0, false, la, ra, deadline, f)
 	if err != nil {
-		goto Error
+		goto error
 	}
 	return fd, nil
 
-Error:
+error:
 	addr := raddr
-	if mode == "listen" {
+	switch mode {
+	case "listen":
 		addr = laddr
 	}
 	return nil, &OpError{Op: mode, Net: net, Addr: addr, Err: err}
@@ -108,21 +102,21 @@ func sotypeToNet(sotype int) string {
 	return ""
 }
 
-// UnixConn is an implementation of the Conn interface
-// for connections to Unix domain sockets.
+// UnixConn is an implementation of the Conn interface for connections
+// to Unix domain sockets.
 type UnixConn struct {
 	conn
 }
 
 func newUnixConn(fd *netFD) *UnixConn { return &UnixConn{conn{fd}} }
 
-// ReadFromUnix reads a packet from c, copying the payload into b.
-// It returns the number of bytes copied into b and the source address
-// of the packet.
+// ReadFromUnix reads a packet from c, copying the payload into b.  It
+// returns the number of bytes copied into b and the source address of
+// the packet.
 //
-// ReadFromUnix can be made to time out and return
-// an error with Timeout() == true after a fixed time limit;
-// see SetDeadline and SetReadDeadline.
+// ReadFromUnix can be made to time out and return an error with
+// Timeout() == true after a fixed time limit; see SetDeadline and
+// SetReadDeadline.
 func (c *UnixConn) ReadFromUnix(b []byte) (n int, addr *UnixAddr, err error) {
 	if !c.ok() {
 		return 0, nil, syscall.EINVAL
@@ -144,12 +138,28 @@ func (c *UnixConn) ReadFrom(b []byte) (n int, addr Addr, err error) {
 	return n, uaddr.toAddr(), err
 }
 
+// ReadMsgUnix reads a packet from c, copying the payload into b and
+// the associated out-of-band data into oob.  It returns the number of
+// bytes copied into b, the number of bytes copied into oob, the flags
+// that were set on the packet, and the source address of the packet.
+func (c *UnixConn) ReadMsgUnix(b, oob []byte) (n, oobn, flags int, addr *UnixAddr, err error) {
+	if !c.ok() {
+		return 0, 0, 0, nil, syscall.EINVAL
+	}
+	n, oobn, flags, sa, err := c.fd.ReadMsg(b, oob)
+	switch sa := sa.(type) {
+	case *syscall.SockaddrUnix:
+		addr = &UnixAddr{sa.Name, sotypeToNet(c.fd.sotype)}
+	}
+	return
+}
+
 // WriteToUnix writes a packet to addr via c, copying the payload from b.
 //
-// WriteToUnix can be made to time out and return
-// an error with Timeout() == true after a fixed time limit;
-// see SetDeadline and SetWriteDeadline.
-// On packet-oriented connections, write timeouts are rare.
+// WriteToUnix can be made to time out and return an error with
+// Timeout() == true after a fixed time limit; see SetDeadline and
+// SetWriteDeadline.  On packet-oriented connections, write timeouts
+// are rare.
 func (c *UnixConn) WriteToUnix(b []byte, addr *UnixAddr) (n int, err error) {
 	if !c.ok() {
 		return 0, syscall.EINVAL
@@ -173,26 +183,9 @@ func (c *UnixConn) WriteTo(b []byte, addr Addr) (n int, err error) {
 	return c.WriteToUnix(b, a)
 }
 
-// ReadMsgUnix reads a packet from c, copying the payload into b
-// and the associated out-of-band data into oob.
-// It returns the number of bytes copied into b, the number of
-// bytes copied into oob, the flags that were set on the packet,
-// and the source address of the packet.
-func (c *UnixConn) ReadMsgUnix(b, oob []byte) (n, oobn, flags int, addr *UnixAddr, err error) {
-	if !c.ok() {
-		return 0, 0, 0, nil, syscall.EINVAL
-	}
-	n, oobn, flags, sa, err := c.fd.ReadMsg(b, oob)
-	switch sa := sa.(type) {
-	case *syscall.SockaddrUnix:
-		addr = &UnixAddr{sa.Name, sotypeToNet(c.fd.sotype)}
-	}
-	return
-}
-
-// WriteMsgUnix writes a packet to addr via c, copying the payload from b
-// and the associated out-of-band data from oob.  It returns the number
-// of payload and out-of-band bytes written.
+// WriteMsgUnix writes a packet to addr via c, copying the payload
+// from b and the associated out-of-band data from oob.  It returns
+// the number of payload and out-of-band bytes written.
 func (c *UnixConn) WriteMsgUnix(b, oob []byte, addr *UnixAddr) (n, oobn int, err error) {
 	if !c.ok() {
 		return 0, 0, syscall.EINVAL
@@ -226,13 +219,18 @@ func (c *UnixConn) CloseWrite() error {
 }
 
 // DialUnix connects to the remote address raddr on the network net,
-// which must be "unix" or "unixgram".  If laddr is not nil, it is used
-// as the local address for the connection.
+// which must be "unix", "unixgram" or "unixpacket".  If laddr is not
+// nil, it is used as the local address for the connection.
 func DialUnix(net string, laddr, raddr *UnixAddr) (*UnixConn, error) {
 	return dialUnix(net, laddr, raddr, noDeadline)
 }
 
 func dialUnix(net string, laddr, raddr *UnixAddr, deadline time.Time) (*UnixConn, error) {
+	switch net {
+	case "unix", "unixgram", "unixpacket":
+	default:
+		return nil, UnknownNetworkError(net)
+	}
 	fd, err := unixSocket(net, laddr, raddr, "dial", deadline)
 	if err != nil {
 		return nil, err
@@ -240,22 +238,25 @@ func dialUnix(net string, laddr, raddr *UnixAddr, deadline time.Time) (*UnixConn
 	return newUnixConn(fd), nil
 }
 
-// UnixListener is a Unix domain socket listener.
-// Clients should typically use variables of type Listener
-// instead of assuming Unix domain sockets.
+// UnixListener is a Unix domain socket listener.  Clients should
+// typically use variables of type Listener instead of assuming Unix
+// domain sockets.
 type UnixListener struct {
 	fd   *netFD
 	path string
 }
 
-// ListenUnix announces on the Unix domain socket laddr and returns a Unix listener.
-// Net must be "unix" (stream sockets).
+// ListenUnix announces on the Unix domain socket laddr and returns a
+// Unix listener.  The network net must be "unix", "unixgram" or
+// "unixpacket".
 func ListenUnix(net string, laddr *UnixAddr) (*UnixListener, error) {
-	if net != "unix" && net != "unixgram" && net != "unixpacket" {
+	switch net {
+	case "unix", "unixgram", "unixpacket":
+	default:
 		return nil, UnknownNetworkError(net)
 	}
-	if laddr != nil {
-		laddr = &UnixAddr{laddr.Name, net} // make our own copy
+	if laddr == nil {
+		return nil, &OpError{"listen", net, nil, errMissingAddress}
 	}
 	fd, err := unixSocket(net, laddr, nil, "listen", noDeadline)
 	if err != nil {
@@ -269,8 +270,8 @@ func ListenUnix(net string, laddr *UnixAddr) (*UnixListener, error) {
 	return &UnixListener{fd, laddr.Name}, nil
 }
 
-// AcceptUnix accepts the next incoming call and returns the new connection
-// and the remote address.
+// AcceptUnix accepts the next incoming call and returns the new
+// connection and the remote address.
 func (l *UnixListener) AcceptUnix() (*UnixConn, error) {
 	if l == nil || l.fd == nil {
 		return nil, syscall.EINVAL
@@ -283,8 +284,8 @@ func (l *UnixListener) AcceptUnix() (*UnixConn, error) {
 	return c, nil
 }
 
-// Accept implements the Accept method in the Listener interface;
-// it waits for the next call and returns a generic Conn.
+// Accept implements the Accept method in the Listener interface; it
+// waits for the next call and returns a generic Conn.
 func (l *UnixListener) Accept() (c Conn, err error) {
 	c1, err := l.AcceptUnix()
 	if err != nil {
@@ -293,8 +294,8 @@ func (l *UnixListener) Accept() (c Conn, err error) {
 	return c1, nil
 }
 
-// Close stops listening on the Unix address.
-// Already accepted connections are not closed.
+// Close stops listening on the Unix address.  Already accepted
+// connections are not closed.
 func (l *UnixListener) Close() error {
 	if l == nil || l.fd == nil {
 		return syscall.EINVAL
@@ -328,16 +329,16 @@ func (l *UnixListener) SetDeadline(t time.Time) (err error) {
 	return setDeadline(l.fd, t)
 }
 
-// File returns a copy of the underlying os.File, set to blocking mode.
-// It is the caller's responsibility to close f when finished.
+// File returns a copy of the underlying os.File, set to blocking
+// mode.  It is the caller's responsibility to close f when finished.
 // Closing l does not affect f, and closing f does not affect l.
 func (l *UnixListener) File() (f *os.File, err error) { return l.fd.dup() }
 
-// ListenUnixgram listens for incoming Unix datagram packets addressed to the
-// local address laddr.  The returned connection c's ReadFrom
-// and WriteTo methods can be used to receive and send UDP
-// packets with per-packet addressing.  The network net must be "unixgram".
-func ListenUnixgram(net string, laddr *UnixAddr) (*UDPConn, error) {
+// ListenUnixgram listens for incoming Unix datagram packets addressed
+// to the local address laddr.  The returned connection c's ReadFrom
+// and WriteTo methods can be used to receive and send packets with
+// per-packet addressing.  The network net must be "unixgram".
+func ListenUnixgram(net string, laddr *UnixAddr) (*UnixConn, error) {
 	switch net {
 	case "unixgram":
 	default:
@@ -350,5 +351,5 @@ func ListenUnixgram(net string, laddr *UnixAddr) (*UDPConn, error) {
 	if err != nil {
 		return nil, err
 	}
-	return newUDPConn(fd), nil
+	return newUnixConn(fd), nil
 }
diff --git a/libgo/go/net/url/url.go b/libgo/go/net/url/url.go
index 692a7fd..71758fe 100644
--- a/libgo/go/net/url/url.go
+++ b/libgo/go/net/url/url.go
@@ -361,6 +361,11 @@ func parse(rawurl string, viaRequest bool) (url *URL, err error) {
 	}
 	url = new(URL)
 
+	if rawurl == "*" {
+		url.Path = "*"
+		return
+	}
+
 	// Split off possible leading "http:", "mailto:", etc.
 	// Cannot contain escaped characters.
 	if url.Scheme, rest, err = getscheme(rawurl); err != nil {
@@ -572,23 +577,33 @@ func resolvePath(basepath string, refpath string) string {
 	if len(base) == 0 {
 		base = []string{""}
 	}
+
+	rm := true
 	for idx, ref := range refs {
 		switch {
 		case ref == ".":
-			base[len(base)-1] = ""
+			if idx == 0 {
+				base[len(base)-1] = ""
+				rm = true
+			} else {
+				rm = false
+			}
 		case ref == "..":
 			newLen := len(base) - 1
 			if newLen < 1 {
 				newLen = 1
 			}
 			base = base[0:newLen]
-			base[len(base)-1] = ""
+			if rm {
+				base[len(base)-1] = ""
+			}
 		default:
 			if idx == 0 || base[len(base)-1] == "" {
 				base[len(base)-1] = ref
 			} else {
 				base = append(base, ref)
 			}
+			rm = false
 		}
 	}
 	return strings.Join(base, "/")
diff --git a/libgo/go/net/url/url_test.go b/libgo/go/net/url/url_test.go
index 64f1170..4d3545d 100644
--- a/libgo/go/net/url/url_test.go
+++ b/libgo/go/net/url/url_test.go
@@ -277,7 +277,7 @@ func TestParse(t *testing.T) {
 
 const pathThatLooksSchemeRelative = "//not.a.user@not.a.host/just/a/path"
 
-var parseRequestUrlTests = []struct {
+var parseRequestURLTests = []struct {
 	url           string
 	expectedValid bool
 }{
@@ -289,10 +289,11 @@ var parseRequestUrlTests = []struct {
 	{"//not.a.user@%66%6f%6f.com/just/a/path/also", true},
 	{"foo.html", false},
 	{"../dir/", false},
+	{"*", true},
 }
 
 func TestParseRequestURI(t *testing.T) {
-	for _, test := range parseRequestUrlTests {
+	for _, test := range parseRequestURLTests {
 		_, err := ParseRequestURI(test.url)
 		valid := err == nil
 		if valid != test.expectedValid {
@@ -536,6 +537,15 @@ var resolveReferenceTests = []struct {
 	{"http://foo.com/bar/baz", "../../../../../quux", "http://foo.com/quux"},
 	{"http://foo.com/bar", "..", "http://foo.com/"},
 	{"http://foo.com/bar/baz", "./..", "http://foo.com/"},
+	// ".." in the middle (issue 3560)
+	{"http://foo.com/bar/baz", "quux/dotdot/../tail", "http://foo.com/bar/quux/tail"},
+	{"http://foo.com/bar/baz", "quux/./dotdot/../tail", "http://foo.com/bar/quux/tail"},
+	{"http://foo.com/bar/baz", "quux/./dotdot/.././tail", "http://foo.com/bar/quux/tail"},
+	{"http://foo.com/bar/baz", "quux/./dotdot/./../tail", "http://foo.com/bar/quux/tail"},
+	{"http://foo.com/bar/baz", "quux/./dotdot/dotdot/././../../tail", "http://foo.com/bar/quux/tail"},
+	{"http://foo.com/bar/baz", "quux/./dotdot/dotdot/./.././../tail", "http://foo.com/bar/quux/tail"},
+	{"http://foo.com/bar/baz", "quux/./dotdot/dotdot/dotdot/./../../.././././tail", "http://foo.com/bar/quux/tail"},
+	{"http://foo.com/bar/baz", "quux/./dotdot/../dotdot/../dot/./tail/..", "http://foo.com/bar/quux/dot"},
 
 	// "." and ".." in the base aren't special
 	{"http://foo.com/dot/./dotdot/../foo/bar", "../baz", "http://foo.com/dot/./dotdot/../baz"},
diff --git a/libgo/go/os/env.go b/libgo/go/os/env.go
index eb265f2..db7fc72 100644
--- a/libgo/go/os/env.go
+++ b/libgo/go/os/env.go
@@ -9,7 +9,7 @@ package os
 import "syscall"
 
 // Expand replaces ${var} or $var in the string based on the mapping function.
-// Invocations of undefined variables are replaced with the empty string.
+// For example, os.ExpandEnv(s) is equivalent to os.Expand(s, os.Getenv).
 func Expand(s string, mapping func(string) string) string {
 	buf := make([]byte, 0, 2*len(s))
 	// ${} is all ASCII, so bytes are fine for this operation.
diff --git a/libgo/go/os/file_posix.go b/libgo/go/os/file_posix.go
index 1ba3293..b979fed 100644
--- a/libgo/go/os/file_posix.go
+++ b/libgo/go/os/file_posix.go
@@ -153,12 +153,10 @@ func (f *File) Sync() (err error) {
 // less precise time unit.
 // If there is an error, it will be of type *PathError.
 func Chtimes(name string, atime time.Time, mtime time.Time) error {
-	var utimes [2]syscall.Timeval
-	atime_ns := atime.Unix()*1e9 + int64(atime.Nanosecond())
-	mtime_ns := mtime.Unix()*1e9 + int64(mtime.Nanosecond())
-	utimes[0] = syscall.NsecToTimeval(atime_ns)
-	utimes[1] = syscall.NsecToTimeval(mtime_ns)
-	if e := syscall.Utimes(name, utimes[0:]); e != nil {
+	var utimes [2]syscall.Timespec
+	utimes[0] = syscall.NsecToTimespec(atime.UnixNano())
+	utimes[1] = syscall.NsecToTimespec(mtime.UnixNano())
+	if e := syscall.UtimesNano(name, utimes[0:]); e != nil {
 		return &PathError{"chtimes", name, e}
 	}
 	return nil
diff --git a/libgo/go/os/user/lookup_unix.go b/libgo/go/os/user/lookup_unix.go
index 7e67495..e1e2777 100644
--- a/libgo/go/os/user/lookup_unix.go
+++ b/libgo/go/os/user/lookup_unix.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin freebsd linux netbsd
+// +build darwin freebsd linux netbsd openbsd
 // +build cgo
 
 package user
diff --git a/libgo/go/regexp/all_test.go b/libgo/go/regexp/all_test.go
index b7e4f04..a6a659c 100644
--- a/libgo/go/regexp/all_test.go
+++ b/libgo/go/regexp/all_test.go
@@ -31,53 +31,52 @@ var good_re = []string{
 	`\!\\`,
 }
 
-/*
 type stringError struct {
 	re  string
-	err error
+	err string
 }
 
 var bad_re = []stringError{
-	{`*`, ErrBareClosure},
-	{`+`, ErrBareClosure},
-	{`?`, ErrBareClosure},
-	{`(abc`, ErrUnmatchedLpar},
-	{`abc)`, ErrUnmatchedRpar},
-	{`x[a-z`, ErrUnmatchedLbkt},
-	{`abc]`, ErrUnmatchedRbkt},
-	{`[z-a]`, ErrBadRange},
-	{`abc\`, ErrExtraneousBackslash},
-	{`a**`, ErrBadClosure},
-	{`a*+`, ErrBadClosure},
-	{`a??`, ErrBadClosure},
-	{`\x`, ErrBadBackslash},
-}
-*/
-
-func compileTest(t *testing.T, expr string, error error) *Regexp {
+	{`*`, "missing argument to repetition operator: `*`"},
+	{`+`, "missing argument to repetition operator: `+`"},
+	{`?`, "missing argument to repetition operator: `?`"},
+	{`(abc`, "missing closing ): `(abc`"},
+	{`abc)`, "unexpected ): `abc)`"},
+	{`x[a-z`, "missing closing ]: `[a-z`"},
+	{`[z-a]`, "invalid character class range: `z-a`"},
+	{`abc\`, "trailing backslash at end of expression"},
+	{`a**`, "invalid nested repetition operator: `**`"},
+	{`a*+`, "invalid nested repetition operator: `*+`"},
+	{`\x`, "invalid escape sequence: `\\x`"},
+}
+
+func compileTest(t *testing.T, expr string, error string) *Regexp {
 	re, err := Compile(expr)
-	if err != error {
+	if error == "" && err != nil {
 		t.Error("compiling `", expr, "`; unexpected error: ", err.Error())
 	}
+	if error != "" && err == nil {
+		t.Error("compiling `", expr, "`; missing error")
+	} else if error != "" && !strings.Contains(err.Error(), error) {
+		t.Error("compiling `", expr, "`; wrong error: ", err.Error(), "; want ", error)
+	}
 	return re
 }
 
 func TestGoodCompile(t *testing.T) {
 	for i := 0; i < len(good_re); i++ {
-		compileTest(t, good_re[i], nil)
+		compileTest(t, good_re[i], "")
 	}
 }
 
-/*
 func TestBadCompile(t *testing.T) {
 	for i := 0; i < len(bad_re); i++ {
 		compileTest(t, bad_re[i].re, bad_re[i].err)
 	}
 }
-*/
 
 func matchTest(t *testing.T, test *FindTest) {
-	re := compileTest(t, test.pat, nil)
+	re := compileTest(t, test.pat, "")
 	if re == nil {
 		return
 	}
diff --git a/libgo/go/regexp/syntax/parse.go b/libgo/go/regexp/syntax/parse.go
index 0bf5799..335f739 100644
--- a/libgo/go/regexp/syntax/parse.go
+++ b/libgo/go/regexp/syntax/parse.go
@@ -42,11 +42,9 @@ const (
 	ErrMissingParen          ErrorCode = "missing closing )"
 	ErrMissingRepeatArgument ErrorCode = "missing argument to repetition operator"
 	ErrTrailingBackslash     ErrorCode = "trailing backslash at end of expression"
+	ErrUnexpectedParen       ErrorCode = "unexpected )"
 )
 
-// TODO: Export for Go 1.1.
-const errUnexpectedParen ErrorCode = "unexpected )"
-
 func (e ErrorCode) String() string {
 	return string(e)
 }
@@ -1167,13 +1165,13 @@ func (p *parser) parseRightParen() error {
 
 	n := len(p.stack)
 	if n < 2 {
-		return &Error{errUnexpectedParen, p.wholeRegexp}
+		return &Error{ErrUnexpectedParen, p.wholeRegexp}
 	}
 	re1 := p.stack[n-1]
 	re2 := p.stack[n-2]
 	p.stack = p.stack[:n-2]
 	if re2.Op != opLeftParen {
-		return &Error{errUnexpectedParen, p.wholeRegexp}
+		return &Error{ErrUnexpectedParen, p.wholeRegexp}
 	}
 	// Restore flags at time of paren.
 	p.flags = re2.Flags
diff --git a/libgo/go/strconv/ftoa.go b/libgo/go/strconv/ftoa.go
index 8067881..1a9c41b 100644
--- a/libgo/go/strconv/ftoa.go
+++ b/libgo/go/strconv/ftoa.go
@@ -255,7 +255,7 @@ func roundShortest(d *decimal, mant uint64, exp int, flt *floatInfo) {
 
 	// d = mant << (exp - mantbits)
 	// Next highest floating point number is mant+1 << exp-mantbits.
-	// Our upper bound is halfway inbetween, mant*2+1 << exp-mantbits-1.
+	// Our upper bound is halfway between, mant*2+1 << exp-mantbits-1.
 	upper := new(decimal)
 	upper.Assign(mant*2 + 1)
 	upper.Shift(exp - int(flt.mantbits) - 1)
@@ -265,7 +265,7 @@ func roundShortest(d *decimal, mant uint64, exp int, flt *floatInfo) {
 	// unless mant-1 drops the significant bit and exp is not the minimum exp,
 	// in which case the next lowest is mant*2-1 << exp-mantbits-1.
 	// Either way, call it mantlo << explo-mantbits.
-	// Our lower bound is halfway inbetween, mantlo*2+1 << explo-mantbits-1.
+	// Our lower bound is halfway between, mantlo*2+1 << explo-mantbits-1.
 	var mantlo uint64
 	var explo int
 	if mant > 1<<flt.mantbits || exp == minexp {
diff --git a/libgo/go/syscall/env_plan9.go b/libgo/go/syscall/env_plan9.go
index 2848d9b..0f89aa9 100644
--- a/libgo/go/syscall/env_plan9.go
+++ b/libgo/go/syscall/env_plan9.go
@@ -12,14 +12,17 @@ import (
 )
 
 var (
-	// envOnce guards initialization by copyenv, which populates env.
+	// envOnce guards copyenv, which populates env.
 	envOnce sync.Once
 
 	// envLock guards env.
 	envLock sync.RWMutex
 
 	// env maps from an environment variable to its value.
-	env map[string]string
+	env = make(map[string]string)
+
+	errZeroLengthKey = errors.New("zero length key")
+	errShortWrite    = errors.New("i/o count too small")
 )
 
 func readenv(key string) (string, error) {
@@ -47,12 +50,18 @@ func writeenv(key, value string) error {
 		return err
 	}
 	defer Close(fd)
-	_, err = Write(fd, []byte(value))
-	return err
+	b := []byte(value)
+	n, err := Write(fd, b)
+	if err != nil {
+		return err
+	}
+	if n != len(b) {
+		return errShortWrite
+	}
+	return nil
 }
 
 func copyenv() {
-	env = make(map[string]string)
 	fd, err := Open("/env", O_RDONLY)
 	if err != nil {
 		return
@@ -72,7 +81,6 @@ func copyenv() {
 }
 
 func Getenv(key string) (value string, found bool) {
-	envOnce.Do(copyenv)
 	if len(key) == 0 {
 		return "", false
 	}
@@ -80,17 +88,20 @@ func Getenv(key string) (value string, found bool) {
 	envLock.RLock()
 	defer envLock.RUnlock()
 
-	v, ok := env[key]
-	if !ok {
+	if v, ok := env[key]; ok {
+		return v, true
+	}
+	v, err := readenv(key)
+	if err != nil {
 		return "", false
 	}
+	env[key] = v
 	return v, true
 }
 
 func Setenv(key, value string) error {
-	envOnce.Do(copyenv)
 	if len(key) == 0 {
-		return errors.New("zero length key")
+		return errZeroLengthKey
 	}
 
 	envLock.Lock()
@@ -105,8 +116,6 @@ func Setenv(key, value string) error {
 }
 
 func Clearenv() {
-	envOnce.Do(copyenv) // prevent copyenv in Getenv/Setenv
-
 	envLock.Lock()
 	defer envLock.Unlock()
 
@@ -115,9 +124,10 @@ func Clearenv() {
 }
 
 func Environ() []string {
-	envOnce.Do(copyenv)
 	envLock.RLock()
 	defer envLock.RUnlock()
+
+	envOnce.Do(copyenv)
 	a := make([]string, len(env))
 	i := 0
 	for k, v := range env {
diff --git a/libgo/go/syscall/libcall_linux_utimesnano.go b/libgo/go/syscall/libcall_linux_utimesnano.go
new file mode 100644
index 0000000..043ab0d
--- /dev/null
+++ b/libgo/go/syscall/libcall_linux_utimesnano.go
@@ -0,0 +1,29 @@
+// Copyright 2012 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.
+
+// GNU/Linux version of UtimesNano.
+
+package syscall
+
+import "unsafe"
+
+//sys	utimensat(dirfd int, path string, times *[2]Timespec, flags int) (err error)
+//utimensat(dirfd int, path *byte, times *[2]Timespec, flags int) int
+func UtimesNano(path string, ts []Timespec) (err error) {
+	if len(ts) != 2 {
+		return EINVAL
+	}
+	err = utimensat(_AT_FDCWD, path, (*[2]Timespec)(unsafe.Pointer(&ts[0])), 0)
+	if err != ENOSYS {
+		return err
+	}
+	// If the utimensat syscall isn't available (utimensat was added to Linux
+	// in 2.6.22, Released, 8 July 2007) then fall back to utimes
+	var tv [2]Timeval
+	for i := 0; i < 2; i++ {
+		tv[i].Sec = Timeval_sec_t(ts[i].Sec)
+		tv[i].Usec = Timeval_usec_t(ts[i].Nsec / 1000)
+	}
+	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
+}
diff --git a/libgo/go/syscall/libcall_posix_utimesnano.go b/libgo/go/syscall/libcall_posix_utimesnano.go
new file mode 100644
index 0000000..e0751f5
--- /dev/null
+++ b/libgo/go/syscall/libcall_posix_utimesnano.go
@@ -0,0 +1,24 @@
+// Copyright 2012 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.
+
+// General POSIX version of UtimesNano.
+
+package syscall
+
+import "unsafe"
+
+func UtimesNano(path string, ts []Timespec) error {
+	// TODO: The BSDs can do utimensat with SYS_UTIMENSAT but it
+	// isn't supported by darwin so this uses utimes instead
+	if len(ts) != 2 {
+		return EINVAL
+	}
+	// Not as efficient as it could be because Timespec and
+	// Timeval have different types in the different OSes
+	tv := [2]Timeval{
+		NsecToTimeval(TimespecToNsec(ts[0])),
+		NsecToTimeval(TimespecToNsec(ts[1])),
+	}
+	return utimes(path, (*[2]Timeval)(unsafe.Pointer(&tv[0])))
+}
diff --git a/libgo/go/syscall/syscall.go b/libgo/go/syscall/syscall.go
index 56296c8..c4f2125 100644
--- a/libgo/go/syscall/syscall.go
+++ b/libgo/go/syscall/syscall.go
@@ -3,10 +3,15 @@
 // license that can be found in the LICENSE file.
 
 // Package syscall contains an interface to the low-level operating system
-// primitives.  The details vary depending on the underlying system.
-// Its primary use is inside other packages that provide a more portable
-// interface to the system, such as "os", "time" and "net".  Use those
-// packages rather than this one if you can.
+// primitives.  The details vary depending on the underlying system, and
+// by default, godoc will display the syscall documentation for the current
+// system.  If you want godoc to display syscall documentation for another
+// system, set $GOOS and $GOARCH to the desired system.  For example, if
+// you want to view documentation for freebsd/arm on linux/amd64, set $GOOS
+// to freebsd and $GOARCH to arm.
+// The primary use of syscall is inside other packages that provide a more
+// portable interface to the system, such as "os", "time" and "net".  Use
+// those packages rather than this one if you can.
 // For details of the functions and data types in this package consult
 // the manuals for the appropriate operating system.
 // These calls return err == nil to indicate success; otherwise
diff --git a/libgo/go/testing/example.go b/libgo/go/testing/example.go
index 671c798..dc97255 100644
--- a/libgo/go/testing/example.go
+++ b/libgo/go/testing/example.go
@@ -24,7 +24,7 @@ func RunExamples(matchString func(pat, str string) (bool, error), examples []Int
 
 	var eg InternalExample
 
-	stdout, stderr := os.Stdout, os.Stderr
+	stdout := os.Stdout
 
 	for _, eg = range examples {
 		matched, err := matchString(*match, eg.Name)
@@ -39,19 +39,19 @@ func RunExamples(matchString func(pat, str string) (bool, error), examples []Int
 			fmt.Printf("=== RUN: %s\n", eg.Name)
 		}
 
-		// capture stdout and stderr
+		// capture stdout
 		r, w, err := os.Pipe()
 		if err != nil {
 			fmt.Fprintln(os.Stderr, err)
 			os.Exit(1)
 		}
-		os.Stdout, os.Stderr = w, w
+		os.Stdout = w
 		outC := make(chan string)
 		go func() {
 			buf := new(bytes.Buffer)
 			_, err := io.Copy(buf, r)
 			if err != nil {
-				fmt.Fprintf(stderr, "testing: copying pipe: %v\n", err)
+				fmt.Fprintf(os.Stderr, "testing: copying pipe: %v\n", err)
 				os.Exit(1)
 			}
 			outC <- buf.String()
@@ -62,9 +62,9 @@ func RunExamples(matchString func(pat, str string) (bool, error), examples []Int
 		eg.F()
 		dt := time.Now().Sub(t0)
 
-		// close pipe, restore stdout/stderr, get output
+		// close pipe, restore stdout, get output
 		w.Close()
-		os.Stdout, os.Stderr = stdout, stderr
+		os.Stdout = stdout
 		out := <-outC
 
 		// report any errors
diff --git a/libgo/go/time/format.go b/libgo/go/time/format.go
index aab4a4d..417e8f8 100644
--- a/libgo/go/time/format.go
+++ b/libgo/go/time/format.go
@@ -854,9 +854,15 @@ func Parse(layout, value string) (Time, error) {
 			zoneName = p
 
 		case stdFracSecond0:
-			ndigit := std >> stdArgShift
-			nsec, rangeErrString, err = parseNanoseconds(value, 1+ndigit)
-			value = value[1+ndigit:]
+			// stdFracSecond0 requires the exact number of digits as specified in
+			// the layout.
+			ndigit := 1 + (std >> stdArgShift)
+			if len(value) < ndigit {
+				err = errBad
+				break
+			}
+			nsec, rangeErrString, err = parseNanoseconds(value, ndigit)
+			value = value[ndigit:]
 
 		case stdFracSecond9:
 			if len(value) < 2 || value[0] != '.' || value[1] < '0' || '9' < value[1] {
@@ -934,8 +940,7 @@ func parseNanoseconds(value string, nbytes int) (ns int, rangeErrString string,
 		err = errBad
 		return
 	}
-	ns, err = atoi(value[1:nbytes])
-	if err != nil {
+	if ns, err = atoi(value[1:nbytes]); err != nil {
 		return
 	}
 	if ns < 0 || 1e9 <= ns {
diff --git a/libgo/go/time/time_test.go b/libgo/go/time/time_test.go
index 1fd575b..0224fed 100644
--- a/libgo/go/time/time_test.go
+++ b/libgo/go/time/time_test.go
@@ -469,7 +469,7 @@ type ParseTest struct {
 	value      string
 	hasTZ      bool // contains a time zone
 	hasWD      bool // contains a weekday
-	yearSign   int  // sign of year
+	yearSign   int  // sign of year, -1 indicates the year is not present in the format
 	fracDigits int  // number of digits of fractional second
 }
 
@@ -514,6 +514,13 @@ var parseTests = []ParseTest{
 	{"", "2006-01-02 15:04:05.999999999 -0700 MST", "2010-02-04 21:00:57.0123 -0800 PST", true, false, 1, 4},
 	{"", "2006-01-02 15:04:05.9999 -0700 MST", "2010-02-04 21:00:57.012345678 -0800 PST", true, false, 1, 9},
 	{"", "2006-01-02 15:04:05.999999999 -0700 MST", "2010-02-04 21:00:57.012345678 -0800 PST", true, false, 1, 9},
+
+	// issue 4502.
+	{"", StampNano, "Feb  4 21:00:57.012345678", false, false, -1, 9},
+	{"", "Jan _2 15:04:05.999", "Feb  4 21:00:57.012300000", false, false, -1, 4},
+	{"", "Jan _2 15:04:05.999", "Feb  4 21:00:57.012345678", false, false, -1, 9},
+	{"", "Jan _2 15:04:05.999999999", "Feb  4 21:00:57.0123", false, false, -1, 4},
+	{"", "Jan _2 15:04:05.999999999", "Feb  4 21:00:57.012345678", false, false, -1, 9},
 }
 
 func TestParse(t *testing.T) {
@@ -549,7 +556,7 @@ func TestRubyParse(t *testing.T) {
 
 func checkTime(time Time, test *ParseTest, t *testing.T) {
 	// The time should be Thu Feb  4 21:00:57 PST 2010
-	if test.yearSign*time.Year() != 2010 {
+	if test.yearSign >= 0 && test.yearSign*time.Year() != 2010 {
 		t.Errorf("%s: bad year: %d not %d", test.name, time.Year(), 2010)
 	}
 	if time.Month() != February {
@@ -630,6 +637,9 @@ var parseErrorTests = []ParseErrorTest{
 	{"Mon Jan _2 15:04:05.000 2006", "Thu Feb  4 23:00:59x01 2010", "cannot parse"},
 	{"Mon Jan _2 15:04:05.000 2006", "Thu Feb  4 23:00:59.xxx 2010", "cannot parse"},
 	{"Mon Jan _2 15:04:05.000 2006", "Thu Feb  4 23:00:59.-123 2010", "fractional second out of range"},
+	// issue 4502. StampNano requires exactly 9 digits of precision.
+	{StampNano, "Dec  7 11:22:01.000000", `cannot parse ".000000" as ".000000000"`},
+	{StampNano, "Dec  7 11:22:01.0000000000", "extra text: 0"},
 }
 
 func TestParseErrors(t *testing.T) {
diff --git a/libgo/go/time/zoneinfo_read.go b/libgo/go/time/zoneinfo_read.go
index 0eb20c7..a5a2de2 100644
--- a/libgo/go/time/zoneinfo_read.go
+++ b/libgo/go/time/zoneinfo_read.go
@@ -174,7 +174,7 @@ func loadZoneData(bytes []byte) (l *Location, err error) {
 		}
 	}
 
-	// Commited to succeed.
+	// Committed to succeed.
 	l = &Location{zone: zone, tx: tx}
 
 	// Fill in the cache with information about right now,
diff --git a/libgo/merge.sh b/libgo/merge.sh
index 79ece62..ca358ac 100755
--- a/libgo/merge.sh
+++ b/libgo/merge.sh
@@ -163,7 +163,7 @@ done
   done
 done
 
-runtime="chan.c cpuprof.c lock_futex.c lock_sema.c mcache.c mcentral.c mfinal.c mfixalloc.c mgc0.c mheap.c msize.c panic.c print.c proc.c race.h runtime.c runtime.h signal_unix.c malloc.h malloc.goc mprof.goc parfor.c runtime1.goc sema.goc sigqueue.goc string.goc time.goc"
+runtime="chan.c cpuprof.c env_posix.c lock_futex.c lock_sema.c mcache.c mcentral.c mfinal.c mfixalloc.c mgc0.c mgc0.h mheap.c msize.c panic.c print.c proc.c race.h runtime.c runtime.h signal_unix.c malloc.h malloc.goc mprof.goc parfor.c runtime1.goc sema.goc sigqueue.goc string.goc time.goc"
 for f in $runtime; do
   merge_c $f $f
 done
diff --git a/libgo/runtime/env_posix.c b/libgo/runtime/env_posix.c
new file mode 100644
index 0000000..31f4179
--- /dev/null
+++ b/libgo/runtime/env_posix.c
@@ -0,0 +1,37 @@
+// Copyright 2012 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.
+
+// +build darwin freebsd linux netbsd openbsd windows
+
+#include "runtime.h"
+#include "array.h"
+
+extern Slice syscall_Envs asm ("syscall.Envs");
+
+const byte*
+runtime_getenv(const char *s)
+{
+	int32 i, j, len;
+	const byte *v, *bs;
+	String* envv;
+	int32 envc;
+
+	bs = (const byte*)s;
+	len = runtime_findnull(bs);
+	envv = (String*)syscall_Envs.__values;
+	envc = syscall_Envs.__count;
+	for(i=0; i<envc; i++){
+		if(envv[i].len <= len)
+			continue;
+		v = (const byte*)envv[i].str;
+		for(j=0; j<len; j++)
+			if(bs[j] != v[j])
+				goto nomatch;
+		if(v[len] != '=')
+			goto nomatch;
+		return v+len+1;
+	nomatch:;
+	}
+	return nil;
+}
diff --git a/libgo/runtime/go-trampoline.c b/libgo/runtime/go-trampoline.c
index 2d8d9e6..17f73d4 100644
--- a/libgo/runtime/go-trampoline.c
+++ b/libgo/runtime/go-trampoline.c
@@ -106,8 +106,8 @@ __go_allocate_trampoline (uintptr_t size, void *closure)
    no other references to it.  */
 
 void
-runtime_trampoline_scan (void (*addroot) (byte *, uintptr))
+runtime_trampoline_scan (void (*addroot) (Obj))
 {
   if (trampoline_page != NULL)
-    addroot ((byte *) &trampoline_page, sizeof trampoline_page);
+    addroot ((Obj){(byte *) &trampoline_page, sizeof trampoline_page, 0});
 }
diff --git a/libgo/runtime/malloc.goc b/libgo/runtime/malloc.goc
index f1f3fcd..2a614e5 100644
--- a/libgo/runtime/malloc.goc
+++ b/libgo/runtime/malloc.goc
@@ -491,7 +491,7 @@ runtime_MHeap_SysAlloc(MHeap *h, uintptr n)
 static Lock settype_lock;
 
 void
-runtime_settype_flush(M *m, bool sysalloc)
+runtime_settype_flush(M *mp, bool sysalloc)
 {
 	uintptr *buf, *endbuf;
 	uintptr size, ofs, j, t;
@@ -503,8 +503,8 @@ runtime_settype_flush(M *m, bool sysalloc)
 	uintptr typ, p;
 	MSpan *s;
 
-	buf = m->settype_buf;
-	endbuf = buf + m->settype_bufsize;
+	buf = mp->settype_buf;
+	endbuf = buf + mp->settype_bufsize;
 
 	runtime_lock(&settype_lock);
 	while(buf < endbuf) {
@@ -602,7 +602,7 @@ runtime_settype_flush(M *m, bool sysalloc)
 	}
 	runtime_unlock(&settype_lock);
 
-	m->settype_bufsize = 0;
+	mp->settype_bufsize = 0;
 }
 
 // It is forbidden to use this function if it is possible that
@@ -610,7 +610,7 @@ runtime_settype_flush(M *m, bool sysalloc)
 void
 runtime_settype(void *v, uintptr t)
 {
-	M *m1;
+	M *mp;
 	uintptr *buf;
 	uintptr i;
 	MSpan *s;
@@ -618,16 +618,16 @@ runtime_settype(void *v, uintptr t)
 	if(t == 0)
 		runtime_throw("settype: zero type");
 
-	m1 = runtime_m();
-	buf = m1->settype_buf;
-	i = m1->settype_bufsize;
+	mp = runtime_m();
+	buf = mp->settype_buf;
+	i = mp->settype_bufsize;
 	buf[i+0] = (uintptr)v;
 	buf[i+1] = t;
 	i += 2;
-	m1->settype_bufsize = i;
+	mp->settype_bufsize = i;
 
-	if(i == nelem(m1->settype_buf)) {
-		runtime_settype_flush(m1, false);
+	if(i == nelem(mp->settype_buf)) {
+		runtime_settype_flush(mp, false);
 	}
 
 	if(DebugTypeAtBlockEnd) {
diff --git a/libgo/runtime/malloc.h b/libgo/runtime/malloc.h
index b3baaec..710484e 100644
--- a/libgo/runtime/malloc.h
+++ b/libgo/runtime/malloc.h
@@ -468,17 +468,25 @@ enum
 	FlagNoGC = 1<<2,	// must not free or scan for pointers
 };
 
+typedef struct Obj Obj;
+struct Obj
+{
+	byte	*p;	// data pointer
+	uintptr	n;	// size of data in bytes
+	uintptr	ti;	// type info
+};
+
 void	runtime_MProf_Malloc(void*, uintptr);
 void	runtime_MProf_Free(void*, uintptr);
 void	runtime_MProf_GC(void);
-void	runtime_MProf_Mark(void (*addroot)(byte *, uintptr));
+void	runtime_MProf_Mark(void (*addroot)(Obj));
 int32	runtime_gcprocs(void);
 void	runtime_helpgc(int32 nproc);
 void	runtime_gchelper(void);
 
 struct __go_func_type;
 bool	runtime_getfinalizer(void *p, bool del, void (**fn)(void*), const struct __go_func_type **ft);
-void	runtime_walkfintab(void (*fn)(void*), void (*scan)(byte *, uintptr));
+void	runtime_walkfintab(void (*fn)(void*), void (*scan)(Obj));
 
 enum
 {
@@ -494,3 +502,6 @@ enum
 void	runtime_gc_m_ptr(Eface*);
 
 void	runtime_memorydump(void);
+
+void	runtime_time_scan(void (*)(Obj));
+void	runtime_trampoline_scan(void (*)(Obj));
diff --git a/libgo/runtime/mfinal.c b/libgo/runtime/mfinal.c
index f2f640a..7c906da 100644
--- a/libgo/runtime/mfinal.c
+++ b/libgo/runtime/mfinal.c
@@ -193,7 +193,7 @@ runtime_getfinalizer(void *p, bool del, void (**fn)(void*), const struct __go_fu
 }
 
 void
-runtime_walkfintab(void (*fn)(void*), void (*addroot)(byte *, uintptr))
+runtime_walkfintab(void (*fn)(void*), void (*addroot)(Obj))
 {
 	void **key;
 	void **ekey;
@@ -206,8 +206,8 @@ runtime_walkfintab(void (*fn)(void*), void (*addroot)(byte *, uintptr))
 		for(; key < ekey; key++)
 			if(*key != nil && *key != ((void*)-1))
 				fn(*key);
-		addroot((byte*)&fintab[i].fkey, sizeof(void*));
-		addroot((byte*)&fintab[i].val, sizeof(void*));
+		addroot((Obj){(byte*)&fintab[i].fkey, sizeof(void*), 0});
+		addroot((Obj){(byte*)&fintab[i].val, sizeof(void*), 0});
 		runtime_unlock(&fintab[i]);
 	}
 }
diff --git a/libgo/runtime/mgc0.c b/libgo/runtime/mgc0.c
index 45f8a56..698400b 100644
--- a/libgo/runtime/mgc0.c
+++ b/libgo/runtime/mgc0.c
@@ -9,6 +9,7 @@
 #include "runtime.h"
 #include "arch.h"
 #include "malloc.h"
+#include "mgc0.h"
 #include "race.h"
 
 #ifdef USING_SPLIT_STACK
@@ -24,11 +25,13 @@ extern void * __splitstack_find_context (void *context[10], size_t *, void **,
 enum {
 	Debug = 0,
 	DebugMark = 0,  // run second pass to check mark
-	DataBlock = 8*1024,
 
 	// Four bits per word (see #defines below).
 	wordsPerBitmapWord = sizeof(void*)*8/4,
 	bitShift = sizeof(void*)*8/4,
+
+	handoffThreshold = 4,
+	IntermediateBufferCapacity = 64,
 };
 
 // Bits in per-word bitmap.
@@ -81,12 +84,16 @@ uint32 runtime_worldsema = 1;
 
 static int32 gctrace;
 
+// The size of Workbuf is N*PageSize.
 typedef struct Workbuf Workbuf;
 struct Workbuf
 {
-	LFNode node; // must be first
+#define SIZE (2*PageSize-sizeof(LFNode)-sizeof(uintptr))
+	LFNode  node; // must be first
 	uintptr nobj;
-	byte *obj[512-(sizeof(LFNode)+sizeof(uintptr))/sizeof(byte*)];
+	Obj     obj[SIZE/sizeof(Obj) - 1];
+	uint8   _padding[SIZE%sizeof(Obj) + sizeof(Obj)];
+#undef SIZE
 };
 
 typedef struct Finalizer Finalizer;
@@ -120,13 +127,6 @@ static Workbuf* getfull(Workbuf*);
 static void	putempty(Workbuf*);
 static Workbuf* handoff(Workbuf*);
 
-typedef struct GcRoot GcRoot;
-struct GcRoot
-{
-	byte *p;
-	uintptr n;
-};
-
 static struct {
 	uint64	full;  // lock-free list of full blocks
 	uint64	empty; // lock-free list of empty blocks
@@ -143,77 +143,122 @@ static struct {
 	byte	*chunk;
 	uintptr	nchunk;
 
-	GcRoot	*roots;
+	Obj	*roots;
 	uint32	nroot;
 	uint32	rootcap;
 } work;
 
-// scanblock scans a block of n bytes starting at pointer b for references
-// to other objects, scanning any it finds recursively until there are no
-// unscanned objects left.  Instead of using an explicit recursion, it keeps
-// a work list in the Workbuf* structures and loops in the main function
-// body.  Keeping an explicit work list is easier on the stack allocator and
-// more efficient.
+enum {
+	// TODO(atom): to be expanded in a next CL
+	GC_DEFAULT_PTR = GC_NUM_INSTR,
+};
+
+// PtrTarget and BitTarget are structures used by intermediate buffers.
+// The intermediate buffers hold GC data before it
+// is moved/flushed to the work buffer (Workbuf).
+// The size of an intermediate buffer is very small,
+// such as 32 or 64 elements.
+struct PtrTarget
+{
+	void *p;
+	uintptr ti;
+};
+
+struct BitTarget
+{
+	void *p;
+	uintptr ti;
+	uintptr *bitp, shift;
+};
+
+struct BufferList
+{
+	struct PtrTarget ptrtarget[IntermediateBufferCapacity];
+	struct BitTarget bittarget[IntermediateBufferCapacity];
+	struct BufferList *next;
+};
+static struct BufferList *bufferList;
+
+static Lock lock;
+
+// flushptrbuf moves data from the PtrTarget buffer to the work buffer.
+// The PtrTarget buffer contains blocks irrespective of whether the blocks have been marked or scanned,
+// while the work buffer contains blocks which have been marked
+// and are prepared to be scanned by the garbage collector.
+//
+// _wp, _wbuf, _nobj are input/output parameters and are specifying the work buffer.
+// bitbuf holds temporary data generated by this function.
+//
+// A simplified drawing explaining how the todo-list moves from a structure to another:
+//
+//     scanblock
+//  (find pointers)
+//    Obj ------> PtrTarget (pointer targets)
+//     ↑          |
+//     |          | flushptrbuf (1st part,
+//     |          | find block start)
+//     |          ↓
+//     `--------- BitTarget (pointer targets and the corresponding locations in bitmap)
+//  flushptrbuf
+//  (2nd part, mark and enqueue)
 static void
-scanblock(byte *b, uintptr n)
+flushptrbuf(struct PtrTarget *ptrbuf, uintptr n, Obj **_wp, Workbuf **_wbuf, uintptr *_nobj, struct BitTarget *bitbuf)
 {
-	byte *obj, *arena_start, *arena_used, *p;
-	void **vp;
-	uintptr size, *bitp, bits, shift, i, j, x, xbits, off, nobj, nproc;
+	byte *p, *arena_start, *obj;
+	uintptr size, *bitp, bits, shift, j, x, xbits, off, nobj, ti;
 	MSpan *s;
 	PageID k;
-	void **wp;
+	Obj *wp;
 	Workbuf *wbuf;
-	bool keepworking;
-
-	if((intptr)n < 0) {
-		runtime_printf("scanblock %p %D\n", b, (int64)n);
-		runtime_throw("scanblock");
-	}
+	struct PtrTarget *ptrbuf_end;
+	struct BitTarget *bitbufpos, *bt;
 
-	// Memory arena parameters.
 	arena_start = runtime_mheap.arena_start;
-	arena_used = runtime_mheap.arena_used;
-	nproc = work.nproc;
 
-	wbuf = nil;  // current work buffer
-	wp = nil;  // storage for next queued pointer (write pointer)
-	nobj = 0;  // number of queued objects
+	wp = *_wp;
+	wbuf = *_wbuf;
+	nobj = *_nobj;
 
-	// Scanblock helpers pass b==nil.
-	// Procs needs to return to make more
-	// calls to scanblock.  But if work.nproc==1 then
-	// might as well process blocks as soon as we
-	// have them.
-	keepworking = b == nil || work.nproc == 1;
+	ptrbuf_end = ptrbuf + n;
 
-	// Align b to a word boundary.
-	off = (uintptr)b & (PtrSize-1);
-	if(off != 0) {
-		b += PtrSize - off;
-		n -= PtrSize - off;
+	// If buffer is nearly full, get a new one.
+	if(wbuf == nil || nobj+n >= nelem(wbuf->obj)) {
+		if(wbuf != nil)
+			wbuf->nobj = nobj;
+		wbuf = getempty(wbuf);
+		wp = wbuf->obj;
+		nobj = 0;
+
+		if(n >= nelem(wbuf->obj))
+			runtime_throw("ptrbuf has to be smaller than WorkBuf");
 	}
 
-	for(;;) {
-		// Each iteration scans the block b of length n, queueing pointers in
-		// the work buffer.
-		if(Debug > 1)
-			runtime_printf("scanblock %p %D\n", b, (int64)n);
+	// TODO(atom): This block is a branch of an if-then-else statement.
+	//             The single-threaded branch may be added in a next CL.
+	{
+		// Multi-threaded version.
 
-		vp = (void**)b;
-		n >>= (2+PtrSize/8);  /* n /= PtrSize (4 or 8) */
-		for(i=0; i<(uintptr)n; i++) {
-			obj = (byte*)vp[i];
+		bitbufpos = bitbuf;
 
-			// Words outside the arena cannot be pointers.
-			if((byte*)obj < arena_start || (byte*)obj >= arena_used)
-				continue;
+		while(ptrbuf < ptrbuf_end) {
+			obj = ptrbuf->p;
+			ti = ptrbuf->ti;
+			ptrbuf++;
+
+			// obj belongs to interval [mheap.arena_start, mheap.arena_used).
+			if(Debug > 1) {
+				if(obj < runtime_mheap.arena_start || obj >= runtime_mheap.arena_used)
+					runtime_throw("object is outside of mheap");
+			}
 
 			// obj may be a pointer to a live object.
 			// Try to find the beginning of the object.
 
 			// Round down to word boundary.
-			obj = (void*)((uintptr)obj & ~((uintptr)PtrSize-1));
+			if(((uintptr)obj & ((uintptr)PtrSize-1)) != 0) {
+				obj = (void*)((uintptr)obj & ~((uintptr)PtrSize-1));
+				ti = 0;
+			}
 
 			// Find bits for this word.
 			off = (uintptr*)obj - (uintptr*)arena_start;
@@ -226,6 +271,8 @@ scanblock(byte *b, uintptr n)
 			if((bits & (bitAllocated|bitBlockBoundary)) != 0)
 				goto found;
 
+			ti = 0;
+
 			// Pointing just past the beginning?
 			// Scan backward a little to find a block boundary.
 			for(j=shift; j-->0; ) {
@@ -246,13 +293,13 @@ scanblock(byte *b, uintptr n)
 			s = runtime_mheap.map[x];
 			if(s == nil || k < s->start || k - s->start >= s->npages || s->state != MSpanInUse)
 				continue;
-			p =  (byte*)((uintptr)s->start<<PageShift);
+			p = (byte*)((uintptr)s->start<<PageShift);
 			if(s->sizeclass == 0) {
 				obj = p;
 			} else {
 				if((byte*)obj >= (byte*)s->limit)
 					continue;
-				size = runtime_class_to_size[s->sizeclass];
+				size = s->elemsize;
 				int32 i = ((byte*)obj - p)/size;
 				obj = p+i*size;
 			}
@@ -265,81 +312,203 @@ scanblock(byte *b, uintptr n)
 			bits = xbits >> shift;
 
 		found:
-			// If another proc wants a pointer, give it some.
-			if(work.nwait > 0 && nobj > 4 && work.full == 0) {
-				wbuf->nobj = nobj;
-				wbuf = handoff(wbuf);
-				nobj = wbuf->nobj;
-				wp = (void**)(wbuf->obj + nobj);
-			}
-
 			// Now we have bits, bitp, and shift correct for
 			// obj pointing at the base of the object.
 			// Only care about allocated and not marked.
 			if((bits & (bitAllocated|bitMarked)) != bitAllocated)
 				continue;
-			if(nproc == 1)
-				*bitp |= bitMarked<<shift;
-			else {
-				for(;;) {
-					x = *bitp;
-					if(x & (bitMarked<<shift))
-						goto continue_obj;
-					if(runtime_casp((void**)bitp, (void*)x, (void*)(x|(bitMarked<<shift))))
-						break;
-				}
-			}
+
+			*bitbufpos = (struct BitTarget){obj, ti, bitp, shift};
+			bitbufpos++;
+		}
+
+		runtime_lock(&lock);
+		for(bt=bitbuf; bt<bitbufpos; bt++){
+			xbits = *bt->bitp;
+			bits = xbits >> bt->shift;
+			if((bits & bitMarked) != 0)
+				continue;
+
+			// Mark the block
+			*bt->bitp = xbits | (bitMarked << bt->shift);
 
 			// If object has no pointers, don't need to scan further.
 			if((bits & bitNoPointers) != 0)
 				continue;
 
+			obj = bt->p;
+
+			// Ask span about size class.
+			// (Manually inlined copy of MHeap_Lookup.)
+			x = (uintptr)obj >> PageShift;
+			if(sizeof(void*) == 8)
+				x -= (uintptr)arena_start>>PageShift;
+			s = runtime_mheap.map[x];
+
 			PREFETCH(obj);
 
-			// If buffer is full, get a new one.
-			if(wbuf == nil || nobj >= nelem(wbuf->obj)) {
-				if(wbuf != nil)
-					wbuf->nobj = nobj;
-				wbuf = getempty(wbuf);
-				wp = (void**)(wbuf->obj);
-				nobj = 0;
-			}
-			*wp++ = obj;
+			*wp = (Obj){obj, s->elemsize, bt->ti};
+			wp++;
 			nobj++;
-		continue_obj:;
 		}
+		runtime_unlock(&lock);
+
+		// If another proc wants a pointer, give it some.
+		if(work.nwait > 0 && nobj > handoffThreshold && work.full == 0) {
+			wbuf->nobj = nobj;
+			wbuf = handoff(wbuf);
+			nobj = wbuf->nobj;
+			wp = wbuf->obj + nobj;
+		}
+	}
+
+	*_wp = wp;
+	*_wbuf = wbuf;
+	*_nobj = nobj;
+}
+
+// Program that scans the whole block and treats every block element as a potential pointer
+static uintptr defaultProg[2] = {PtrSize, GC_DEFAULT_PTR};
+
+// scanblock scans a block of n bytes starting at pointer b for references
+// to other objects, scanning any it finds recursively until there are no
+// unscanned objects left.  Instead of using an explicit recursion, it keeps
+// a work list in the Workbuf* structures and loops in the main function
+// body.  Keeping an explicit work list is easier on the stack allocator and
+// more efficient.
+//
+// wbuf: current work buffer
+// wp:   storage for next queued pointer (write pointer)
+// nobj: number of queued objects
+static void
+scanblock(Workbuf *wbuf, Obj *wp, uintptr nobj, bool keepworking)
+{
+	byte *b, *arena_start, *arena_used;
+	uintptr n, i, end_b;
+	void *obj;
+
+	// TODO(atom): to be expanded in a next CL
+	struct Frame {uintptr count, b; uintptr *loop_or_ret;};
+	struct Frame stack_top;
+
+	uintptr *pc;
+
+	struct BufferList *scanbuffers;
+	struct PtrTarget *ptrbuf, *ptrbuf_end;
+	struct BitTarget *bitbuf;
+
+	struct PtrTarget *ptrbufpos;
+
+	// End of local variable declarations.
+
+	if(sizeof(Workbuf) % PageSize != 0)
+		runtime_throw("scanblock: size of Workbuf is suboptimal");
+
+	// Memory arena parameters.
+	arena_start = runtime_mheap.arena_start;
+	arena_used = runtime_mheap.arena_used;
+
+	// Allocate ptrbuf, bitbuf
+	{
+		runtime_lock(&lock);
+
+		if(bufferList == nil) {
+			bufferList = runtime_SysAlloc(sizeof(*bufferList));
+			bufferList->next = nil;
+		}
+		scanbuffers = bufferList;
+		bufferList = bufferList->next;
+
+		ptrbuf = &scanbuffers->ptrtarget[0];
+		ptrbuf_end = &scanbuffers->ptrtarget[0] + nelem(scanbuffers->ptrtarget);
+		bitbuf = &scanbuffers->bittarget[0];
+
+		runtime_unlock(&lock);
+	}
+
+	ptrbufpos = ptrbuf;
+
+	goto next_block;
 
+	for(;;) {
+		// Each iteration scans the block b of length n, queueing pointers in
+		// the work buffer.
+		if(Debug > 1) {
+			runtime_printf("scanblock %p %D\n", b, (int64)n);
+		}
+
+		// TODO(atom): to be replaced in a next CL
+		pc = defaultProg;
+
+		pc++;
+		stack_top.b = (uintptr)b;
+
+		end_b = (uintptr)b + n - PtrSize;
+
+	next_instr:
+		// TODO(atom): to be expanded in a next CL
+		switch(pc[0]) {
+		case GC_DEFAULT_PTR:
+			while(true) {
+				i = stack_top.b;
+				if(i > end_b)
+					goto next_block;
+				stack_top.b += PtrSize;
+
+				obj = *(byte**)i;
+				if((byte*)obj >= arena_start && (byte*)obj < arena_used) {
+					*ptrbufpos = (struct PtrTarget){obj, 0};
+					ptrbufpos++;
+					if(ptrbufpos == ptrbuf_end)
+						goto flush_buffers;
+				}
+			}
+
+		default:
+			runtime_throw("scanblock: invalid GC instruction");
+			return;
+		}
+
+	flush_buffers:
+		flushptrbuf(ptrbuf, ptrbufpos-ptrbuf, &wp, &wbuf, &nobj, bitbuf);
+		ptrbufpos = ptrbuf;
+		goto next_instr;
+
+	next_block:
 		// Done scanning [b, b+n).  Prepare for the next iteration of
-		// the loop by setting b and n to the parameters for the next block.
+		// the loop by setting b, n to the parameters for the next block.
 
-		// Fetch b from the work buffer.
 		if(nobj == 0) {
-			if(!keepworking) {
-				if(wbuf)
-					putempty(wbuf);
-				return;
+			flushptrbuf(ptrbuf, ptrbufpos-ptrbuf, &wp, &wbuf, &nobj, bitbuf);
+			ptrbufpos = ptrbuf;
+
+			if(nobj == 0) {
+				if(!keepworking) {
+					if(wbuf)
+						putempty(wbuf);
+					goto endscan;
+				}
+				// Emptied our buffer: refill.
+				wbuf = getfull(wbuf);
+				if(wbuf == nil)
+					goto endscan;
+				nobj = wbuf->nobj;
+				wp = wbuf->obj + wbuf->nobj;
 			}
-			// Emptied our buffer: refill.
-			wbuf = getfull(wbuf);
-			if(wbuf == nil)
-				return;
-			nobj = wbuf->nobj;
-			wp = (void**)(wbuf->obj + wbuf->nobj);
 		}
-		b = *--wp;
-		nobj--;
 
-		// Ask span about size class.
-		// (Manually inlined copy of MHeap_Lookup.)
-		x = (uintptr)b>>PageShift;
-		if(sizeof(void*) == 8)
-			x -= (uintptr)arena_start>>PageShift;
-		s = runtime_mheap.map[x];
-		if(s->sizeclass == 0)
-			n = s->npages<<PageShift;
-		else
-			n = runtime_class_to_size[s->sizeclass];
+		// Fetch b from the work buffer.
+		--wp;
+		b = wp->p;
+		n = wp->n;
+		nobj--;
 	}
+
+endscan:
+	runtime_lock(&lock);
+	scanbuffers->next = bufferList;
+	bufferList = scanbuffers;
+	runtime_unlock(&lock);
 }
 
 // debug_scanblock is the debug copy of scanblock.
@@ -386,13 +555,12 @@ debug_scanblock(byte *b, uintptr n)
 			continue;
 
 		p =  (byte*)((uintptr)s->start<<PageShift);
+		size = s->elemsize;
 		if(s->sizeclass == 0) {
 			obj = p;
-			size = (uintptr)s->npages<<PageShift;
 		} else {
 			if((byte*)obj >= (byte*)s->limit)
 				continue;
-			size = runtime_class_to_size[s->sizeclass];
 			int32 i = ((byte*)obj - p)/size;
 			obj = p+i*size;
 		}
@@ -421,11 +589,74 @@ debug_scanblock(byte *b, uintptr n)
 	}
 }
 
+// Append obj to the work buffer.
+// _wbuf, _wp, _nobj are input/output parameters and are specifying the work buffer.
+static void
+enqueue(Obj obj, Workbuf **_wbuf, Obj **_wp, uintptr *_nobj)
+{
+	uintptr nobj, off;
+	Obj *wp;
+	Workbuf *wbuf;
+
+	if(Debug > 1)
+		runtime_printf("append obj(%p %D %p)\n", obj.p, (int64)obj.n, obj.ti);
+
+	// Align obj.b to a word boundary.
+	off = (uintptr)obj.p & (PtrSize-1);
+	if(off != 0) {
+		obj.p += PtrSize - off;
+		obj.n -= PtrSize - off;
+		obj.ti = 0;
+	}
+
+	if(obj.p == nil || obj.n == 0)
+		return;
+
+	// Load work buffer state
+	wp = *_wp;
+	wbuf = *_wbuf;
+	nobj = *_nobj;
+
+	// If another proc wants a pointer, give it some.
+	if(work.nwait > 0 && nobj > handoffThreshold && work.full == 0) {
+		wbuf->nobj = nobj;
+		wbuf = handoff(wbuf);
+		nobj = wbuf->nobj;
+		wp = wbuf->obj + nobj;
+	}
+
+	// If buffer is full, get a new one.
+	if(wbuf == nil || nobj >= nelem(wbuf->obj)) {
+		if(wbuf != nil)
+			wbuf->nobj = nobj;
+		wbuf = getempty(wbuf);
+		wp = wbuf->obj;
+		nobj = 0;
+	}
+
+	*wp = obj;
+	wp++;
+	nobj++;
+
+	// Save work buffer state
+	*_wp = wp;
+	*_wbuf = wbuf;
+	*_nobj = nobj;
+}
+
 static void
 markroot(ParFor *desc, uint32 i)
 {
+	Obj *wp;
+	Workbuf *wbuf;
+	uintptr nobj;
+
 	USED(&desc);
-	scanblock(work.roots[i].p, work.roots[i].n);
+	wp = nil;
+	wbuf = nil;
+	nobj = 0;
+	enqueue(work.roots[i], &wbuf, &wp, &nobj);
+	scanblock(wbuf, wp, nobj, false);
 }
 
 // Get an empty work buffer off the work.empty list,
@@ -520,25 +751,24 @@ handoff(Workbuf *b)
 }
 
 static void
-addroot(byte *p, uintptr n)
+addroot(Obj obj)
 {
 	uint32 cap;
-	GcRoot *new;
+	Obj *new;
 
 	if(work.nroot >= work.rootcap) {
-		cap = PageSize/sizeof(GcRoot);
+		cap = PageSize/sizeof(Obj);
 		if(cap < 2*work.rootcap)
 			cap = 2*work.rootcap;
-		new = (GcRoot*)runtime_SysAlloc(cap*sizeof(GcRoot));
+		new = (Obj*)runtime_SysAlloc(cap*sizeof(Obj));
 		if(work.roots != nil) {
-			runtime_memmove(new, work.roots, work.rootcap*sizeof(GcRoot));
-			runtime_SysFree(work.roots, work.rootcap*sizeof(GcRoot));
+			runtime_memmove(new, work.roots, work.rootcap*sizeof(Obj));
+			runtime_SysFree(work.roots, work.rootcap*sizeof(Obj));
 		}
 		work.roots = new;
 		work.rootcap = cap;
 	}
-	work.roots[work.nroot].p = p;
-	work.roots[work.nroot].n = n;
+	work.roots[work.nroot] = obj;
 	work.nroot++;
 }
 
@@ -582,11 +812,11 @@ addstackroots(G *gp)
 		}
 	}
 	if(sp != nil) {
-		addroot(sp, spsize);
+		addroot((Obj){sp, spsize, 0});
 		while((sp = __splitstack_find(next_segment, next_sp,
 					      &spsize, &next_segment,
 					      &next_sp, &initial_sp)) != nil)
-			addroot(sp, spsize);
+			addroot((Obj){sp, spsize, 0});
 	}
 #else
 	M *mp;
@@ -608,9 +838,9 @@ addstackroots(G *gp)
 	}
 	top = (byte*)gp->gcinitial_sp + gp->gcstack_size;
 	if(top > bottom)
-		addroot(bottom, top - bottom);
+		addroot((Obj){bottom, top - bottom, 0});
 	else
-		addroot(top, bottom - top);
+		addroot((Obj){top, bottom - top, 0});
 #endif
 }
 
@@ -624,7 +854,7 @@ addfinroots(void *v)
 		runtime_throw("mark - finalizer inconsistency");
 
 	// do not mark the finalizer block itself.  just mark the things it points at.
-	addroot(v, size);
+	addroot((Obj){v, size, 0});
 }
 
 static struct root_list* roots;
@@ -656,15 +886,15 @@ addroots(void)
 			void *decl = pr->decl;
 			if(decl == nil)
 				break;
-			addroot(decl, pr->size);
+			addroot((Obj){decl, pr->size, 0});
 			pr++;
 		}
 	}
 
-	addroot((byte*)&runtime_m0, sizeof runtime_m0);
-	addroot((byte*)&runtime_g0, sizeof runtime_g0);
-	addroot((byte*)&runtime_allg, sizeof runtime_allg);
-	addroot((byte*)&runtime_allm, sizeof runtime_allm);
+	addroot((Obj){(byte*)&runtime_m0, sizeof runtime_m0, 0});
+	addroot((Obj){(byte*)&runtime_g0, sizeof runtime_g0, 0});
+	addroot((Obj){(byte*)&runtime_allg, sizeof runtime_allg, 0});
+	addroot((Obj){(byte*)&runtime_allm, sizeof runtime_allm, 0});
 	runtime_MProf_Mark(addroot);
 	runtime_time_scan(addroot);
 	runtime_trampoline_scan(addroot);
@@ -680,12 +910,14 @@ addroots(void)
 				break;
 			case MTypes_Words:
 			case MTypes_Bytes:
-				addroot((byte*)&s->types.data, sizeof(void*));
+				// TODO(atom): consider using defaultProg instead of 0
+				addroot((Obj){(byte*)&s->types.data, sizeof(void*), 0});
 				break;
 			}
 		}
 	}
 
+	// stacks
 	for(gp=runtime_allg; gp!=nil; gp=gp->alllink) {
 		switch(gp->status){
 		default:
@@ -709,9 +941,9 @@ addroots(void)
 	runtime_walkfintab(addfinroots, addroot);
 
 	for(fb=allfin; fb; fb=fb->alllink)
-		addroot((byte*)fb->fin, fb->cnt*sizeof(fb->fin[0]));
+		addroot((Obj){(byte*)fb->fin, fb->cnt*sizeof(fb->fin[0]), 0});
 
-	addroot((byte*)&work, sizeof work);
+	addroot((Obj){(byte*)&work, sizeof work, 0});
 }
 
 static bool
@@ -955,8 +1187,9 @@ runtime_gchelper(void)
 {
 	// parallel mark for over gc roots
 	runtime_parfordo(work.markfor);
+
 	// help other threads scan secondary blocks
-	scanblock(nil, 0);
+	scanblock(nil, nil, 0, true);
 
 	if(DebugMark) {
 		// wait while the main thread executes mark(debug_scanblock)
@@ -983,16 +1216,16 @@ static int32 gcpercent = -2;
 static void
 stealcache(void)
 {
-	M *m;
+	M *mp;
 
-	for(m=runtime_allm; m; m=m->alllink)
-		runtime_MCache_ReleaseAll(m->mcache);
+	for(mp=runtime_allm; mp; mp=mp->alllink)
+		runtime_MCache_ReleaseAll(mp->mcache);
 }
 
 static void
 cachestats(GCStats *stats)
 {
-	M *m;
+	M *mp;
 	MCache *c;
 	uint32 i;
 	uint64 stacks_inuse;
@@ -1003,17 +1236,17 @@ cachestats(GCStats *stats)
 		runtime_memclr((byte*)stats, sizeof(*stats));
 	stacks_inuse = 0;
 	stacks_sys = runtime_stacks_sys;
-	for(m=runtime_allm; m; m=m->alllink) {
-		c = m->mcache;
+	for(mp=runtime_allm; mp; mp=mp->alllink) {
+		c = mp->mcache;
 		runtime_purgecachedstats(c);
-		// stacks_inuse += m->stackalloc->inuse;
-		// stacks_sys += m->stackalloc->sys;
+		// stacks_inuse += mp->stackalloc->inuse;
+		// stacks_sys += mp->stackalloc->sys;
 		if(stats) {
-			src = (uint64*)&m->gcstats;
+			src = (uint64*)&mp->gcstats;
 			dst = (uint64*)stats;
 			for(i=0; i<sizeof(*stats)/sizeof(uint64); i++)
 				dst[i] += src[i];
-			runtime_memclr((byte*)&m->gcstats, sizeof(m->gcstats));
+			runtime_memclr((byte*)&mp->gcstats, sizeof(mp->gcstats));
 		}
 		for(i=0; i<nelem(c->local_by_size); i++) {
 			mstats.by_size[i].nmalloc += c->local_by_size[i].nmalloc;
@@ -1100,7 +1333,7 @@ gc(struct gc_args *args)
 	int64 t0, t1, t2, t3;
 	uint64 heap0, heap1, obj0, obj1;
 	GCStats stats;
-	M *m1;
+	M *mp;
 	uint32 i;
 
 	runtime_semacquire(&runtime_worldsema);
@@ -1116,8 +1349,8 @@ gc(struct gc_args *args)
 	m->gcing = 1;
 	runtime_stoptheworld();
 
-	for(m1=runtime_allm; m1; m1=m1->alllink)
-		runtime_settype_flush(m1, false);
+	for(mp=runtime_allm; mp; mp=mp->alllink)
+		runtime_settype_flush(mp, false);
 
 	heap0 = 0;
 	obj0 = 0;
@@ -1127,26 +1360,27 @@ gc(struct gc_args *args)
 		obj0 = mstats.nmalloc - mstats.nfree;
 	}
 
+	m->locks++;	// disable gc during mallocs in parforalloc
+	if(work.markfor == nil)
+		work.markfor = runtime_parforalloc(MaxGcproc);
+	if(work.sweepfor == nil)
+		work.sweepfor = runtime_parforalloc(MaxGcproc);
+	m->locks--;
+
 	work.nwait = 0;
 	work.ndone = 0;
 	work.debugmarkdone = 0;
 	work.nproc = runtime_gcprocs();
 	addroots();
-	m->locks++;	// disable gc during mallocs in parforalloc
-	if(work.markfor == nil)
-		work.markfor = runtime_parforalloc(MaxGcproc);
 	runtime_parforsetup(work.markfor, work.nproc, work.nroot, nil, false, markroot);
-	if(work.sweepfor == nil)
-		work.sweepfor = runtime_parforalloc(MaxGcproc);
 	runtime_parforsetup(work.sweepfor, work.nproc, runtime_mheap.nspan, nil, true, sweepspan);
-	m->locks--;
 	if(work.nproc > 1) {
 		runtime_noteclear(&work.alldone);
 		runtime_helpgc(work.nproc);
 	}
 
 	runtime_parfordo(work.markfor);
-	scanblock(nil, 0);
+	scanblock(nil, nil, 0, true);
 
 	if(DebugMark) {
 		for(i=0; i<work.nroot; i++)
diff --git a/libgo/runtime/mgc0.h b/libgo/runtime/mgc0.h
new file mode 100644
index 0000000..a2798ef
--- /dev/null
+++ b/libgo/runtime/mgc0.h
@@ -0,0 +1,42 @@
+// Copyright 2012 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.
+
+// Garbage collector (GC)
+
+// GC instruction opcodes.
+//
+// The opcode of an instruction is followed by zero or more
+// arguments to the instruction.
+//
+// Meaning of arguments:
+//   off      Offset (in bytes) from the start of the current object
+//   objgc    Pointer to GC info of an object
+//   len      Length of an array
+//   elemsize Size (in bytes) of an element
+//   size     Size (in bytes)
+enum {
+	GC_END,         // End of object, loop or subroutine. Args: none
+	GC_PTR,         // A typed pointer. Args: (off, objgc)
+	GC_APTR,        // Pointer to an arbitrary object. Args: (off)
+	GC_ARRAY_START, // Start an array with a fixed length. Args: (off, len, elemsize)
+	GC_ARRAY_NEXT,  // The next element of an array. Args: none
+	GC_CALL,        // Call a subroutine. Args: (off, objgc)
+	GC_MAP_PTR,     // Go map. Args: (off, MapType*)
+	GC_STRING,      // Go string. Args: (off)
+	GC_EFACE,       // interface{}. Args: (off)
+	GC_IFACE,       // interface{...}. Args: (off)
+	GC_SLICE,       // Go slice. Args: (off, objgc)
+	GC_REGION,      // A region/part of the current object. Args: (off, size, objgc)
+
+	GC_NUM_INSTR,   // Number of instruction opcodes
+};
+
+enum {
+	// Size of GC's fixed stack.
+	//
+	// The current GC implementation permits:
+	//  - at most 1 stack allocation because of GC_CALL
+	//  - at most GC_STACK_CAPACITY allocations because of GC_ARRAY_START
+	GC_STACK_CAPACITY = 8,	
+};
diff --git a/libgo/runtime/mprof.goc b/libgo/runtime/mprof.goc
index a92ef40..8b3a195 100644
--- a/libgo/runtime/mprof.goc
+++ b/libgo/runtime/mprof.goc
@@ -362,13 +362,13 @@ func MemProfile(p Slice, include_inuse_zero bool) (n int, ok bool) {
 }
 
 void
-runtime_MProf_Mark(void (*addroot)(byte *, uintptr))
+runtime_MProf_Mark(void (*addroot)(Obj))
 {
 	// buckhash is not allocated via mallocgc.
-	addroot((byte*)&mbuckets, sizeof mbuckets);
-	addroot((byte*)&bbuckets, sizeof bbuckets);
-	addroot((byte*)&addrhash, sizeof addrhash);
-	addroot((byte*)&addrfree, sizeof addrfree);
+	addroot((Obj){(byte*)&mbuckets, sizeof mbuckets, 0});
+	addroot((Obj){(byte*)&bbuckets, sizeof bbuckets, 0});
+	addroot((Obj){(byte*)&addrhash, sizeof addrhash, 0});
+	addroot((Obj){(byte*)&addrfree, sizeof addrfree, 0});
 }
 
 // Must match BlockProfileRecord in debug.go.
@@ -412,18 +412,18 @@ struct TRecord {
 
 func ThreadCreateProfile(p Slice) (n int, ok bool) {
 	TRecord *r;
-	M *first, *m;
+	M *first, *mp;
 	
 	first = runtime_atomicloadp(&runtime_allm);
 	n = 0;
-	for(m=first; m; m=m->alllink)
+	for(mp=first; mp; mp=mp->alllink)
 		n++;
 	ok = false;
 	if(n <= p.__count) {
 		ok = true;
 		r = (TRecord*)p.__values;
-		for(m=first; m; m=m->alllink) {
-			runtime_memmove(r->stk, m->createstack, sizeof r->stk);
+		for(mp=first; mp; mp=mp->alllink) {
+			runtime_memmove(r->stk, mp->createstack, sizeof r->stk);
 			r++;
 		}
 	}
@@ -471,11 +471,11 @@ func Stack(b Slice, all bool) (n int) {
 }
 
 static void
-saveg(G *g, TRecord *r)
+saveg(G *gp, TRecord *r)
 {
 	int32 n;
 
-	if(g == runtime_g())
+	if(gp == runtime_g())
 		n = runtime_callers(0, r->stk, nelem(r->stk));
 	else {
 		// FIXME: Not implemented.
diff --git a/libgo/runtime/proc.c b/libgo/runtime/proc.c
index d90bb2c..9b229d6 100644
--- a/libgo/runtime/proc.c
+++ b/libgo/runtime/proc.c
@@ -555,13 +555,13 @@ schedlock(void)
 static void
 schedunlock(void)
 {
-	M *m;
+	M *mp;
 
-	m = mwakeup;
+	mp = mwakeup;
 	mwakeup = nil;
 	runtime_unlock(&runtime_sched);
-	if(m != nil)
-		runtime_notewakeup(&m->havenextg);
+	if(mp != nil)
+		runtime_notewakeup(&mp->havenextg);
 }
 
 void
diff --git a/libgo/runtime/runtime.c b/libgo/runtime/runtime.c
index 211edc0..ecd804d 100644
--- a/libgo/runtime/runtime.c
+++ b/libgo/runtime/runtime.c
@@ -79,33 +79,6 @@ runtime_goenvs_unix(void)
 	syscall_Envs.__capacity = n;
 }
 
-const byte*
-runtime_getenv(const char *s)
-{
-	int32 i, j, len;
-	const byte *v, *bs;
-	String* envv;
-	int32 envc;
-
-	bs = (const byte*)s;
-	len = runtime_findnull(bs);
-	envv = (String*)syscall_Envs.__values;
-	envc = syscall_Envs.__count;
-	for(i=0; i<envc; i++){
-		if(envv[i].len <= len)
-			continue;
-		v = (const byte*)envv[i].str;
-		for(j=0; j<len; j++)
-			if(bs[j] != v[j])
-				goto nomatch;
-		if(v[len] != '=')
-			goto nomatch;
-		return v+len+1;
-	nomatch:;
-	}
-	return nil;
-}
-
 int32
 runtime_atoi(const byte *p)
 {
diff --git a/libgo/runtime/runtime.h b/libgo/runtime/runtime.h
index 977ae49..c5cd3a0 100644
--- a/libgo/runtime/runtime.h
+++ b/libgo/runtime/runtime.h
@@ -599,9 +599,6 @@ enum
 	UseSpanType = 1,
 };
 
-void	runtime_time_scan(void (*)(byte*, uintptr));
-void	runtime_trampoline_scan(void (*)(byte *, uintptr));
-
 void	runtime_setsig(int32, bool, bool);
 #define runtime_setitimer setitimer
 
diff --git a/libgo/runtime/time.goc b/libgo/runtime/time.goc
index 5077b71..d497361 100644
--- a/libgo/runtime/time.goc
+++ b/libgo/runtime/time.goc
@@ -255,7 +255,7 @@ siftdown(int32 i)
 }
 
 void
-runtime_time_scan(void (*addroot)(byte*, uintptr))
+runtime_time_scan(void (*addroot)(Obj))
 {
-	addroot((byte*)&timers, sizeof timers);
+	addroot((Obj){(byte*)&timers, sizeof timers, 0});
 }