libgo: update to Go1.17rc2

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/341629

113 files changed, 1224 insertions, 186 deletions

diff --git a/libgo/go/internal/buildcfg/cfg.go b/libgo/go/internal/buildcfg/cfg.go
new file mode 100644
index 0000000..4bf418e
--- /dev/null
+++ b/libgo/go/internal/buildcfg/cfg.go
@@ -0,0 +1,136 @@
+// Copyright 2021 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 buildcfg provides access to the build configuration
+// described by the current environment. It is for use by build tools
+// such as cmd/go or cmd/compile and for setting up go/build's Default context.
+//
+// Note that it does NOT provide access to the build configuration used to
+// build the currently-running binary. For that, use runtime.GOOS etc
+// as well as internal/goexperiment.
+package buildcfg
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+var (
+	defaultGOROOT = defaultGOROOTValue()
+
+	GOROOT   = envOr("GOROOT", defaultGOROOT)
+	GOARCH   = envOr("GOARCH", defaultGOARCH)
+	GOOS     = envOr("GOOS", defaultGOOS)
+	GO386    = envOr("GO386", defaultGO386)
+	GOARM    = goarm()
+	GOMIPS   = gomips()
+	GOMIPS64 = gomips64()
+	GOPPC64  = goppc64()
+	GOWASM   = gowasm()
+	GO_LDSO  = defaultGO_LDSO
+	Version  = version
+)
+
+// Error is one of the errors found (if any) in the build configuration.
+var Error error
+
+// Check exits the program with a fatal error if Error is non-nil.
+func Check() {
+	if Error != nil {
+		fmt.Fprintf(os.Stderr, "%s: %v\n", filepath.Base(os.Args[0]), Error)
+		os.Exit(2)
+	}
+}
+
+func envOr(key, value string) string {
+	if x := os.Getenv(key); x != "" {
+		return x
+	}
+	return value
+}
+
+func goarm() int {
+	def := defaultGOARM
+	if GOOS == "android" && GOARCH == "arm" {
+		// Android arm devices always support GOARM=7.
+		def = "7"
+	}
+	switch v := envOr("GOARM", def); v {
+	case "5":
+		return 5
+	case "6":
+		return 6
+	case "7":
+		return 7
+	}
+	Error = fmt.Errorf("invalid GOARM: must be 5, 6, 7")
+	return int(def[0] - '0')
+}
+
+func gomips() string {
+	switch v := envOr("GOMIPS", defaultGOMIPS); v {
+	case "hardfloat", "softfloat":
+		return v
+	}
+	Error = fmt.Errorf("invalid GOMIPS: must be hardfloat, softfloat")
+	return defaultGOMIPS
+}
+
+func gomips64() string {
+	switch v := envOr("GOMIPS64", defaultGOMIPS64); v {
+	case "hardfloat", "softfloat":
+		return v
+	}
+	Error = fmt.Errorf("invalid GOMIPS64: must be hardfloat, softfloat")
+	return defaultGOMIPS64
+}
+
+func goppc64() int {
+	switch v := envOr("GOPPC64", defaultGOPPC64); v {
+	case "power8":
+		return 8
+	case "power9":
+		return 9
+	}
+	Error = fmt.Errorf("invalid GOPPC64: must be power8, power9")
+	return int(defaultGOPPC64[len("power")] - '0')
+}
+
+type gowasmFeatures struct {
+	SignExt bool
+	SatConv bool
+}
+
+func (f gowasmFeatures) String() string {
+	var flags []string
+	if f.SatConv {
+		flags = append(flags, "satconv")
+	}
+	if f.SignExt {
+		flags = append(flags, "signext")
+	}
+	return strings.Join(flags, ",")
+}
+
+func gowasm() (f gowasmFeatures) {
+	for _, opt := range strings.Split(envOr("GOWASM", ""), ",") {
+		switch opt {
+		case "satconv":
+			f.SatConv = true
+		case "signext":
+			f.SignExt = true
+		case "":
+			// ignore
+		default:
+			Error = fmt.Errorf("invalid GOWASM: no such feature %q", opt)
+		}
+	}
+	return
+}
+
+func Getgoextlinkenabled() string {
+	return envOr("GO_EXTLINK_ENABLED", defaultGO_EXTLINK_ENABLED)
+}
diff --git a/libgo/go/internal/buildcfg/exp.go b/libgo/go/internal/buildcfg/exp.go
new file mode 100644
index 0000000..736c080
--- /dev/null
+++ b/libgo/go/internal/buildcfg/exp.go
@@ -0,0 +1,189 @@
+// Copyright 2021 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 buildcfg
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+
+	"internal/goexperiment"
+)
+
+// Experiment contains the toolchain experiments enabled for the
+// current build.
+//
+// (This is not necessarily the set of experiments the compiler itself
+// was built with.)
+//
+// experimentBaseline specifies the experiment flags that are enabled by
+// default in the current toolchain. This is, in effect, the "control"
+// configuration and any variation from this is an experiment.
+var Experiment, experimentBaseline = func() (goexperiment.Flags, goexperiment.Flags) {
+	flags, baseline, err := ParseGOEXPERIMENT(GOOS, GOARCH, envOr("GOEXPERIMENT", defaultGOEXPERIMENT))
+	if err != nil {
+		Error = err
+	}
+	return flags, baseline
+}()
+
+const DefaultGOEXPERIMENT = defaultGOEXPERIMENT
+
+// FramePointerEnabled enables the use of platform conventions for
+// saving frame pointers.
+//
+// This used to be an experiment, but now it's always enabled on
+// platforms that support it.
+//
+// Note: must agree with runtime.framepointer_enabled.
+var FramePointerEnabled = GOARCH == "amd64" || GOARCH == "arm64"
+
+// ParseGOEXPERIMENT parses a (GOOS, GOARCH, GOEXPERIMENT)
+// configuration tuple and returns the enabled and baseline experiment
+// flag sets.
+//
+// TODO(mdempsky): Move to internal/goexperiment.
+func ParseGOEXPERIMENT(goos, goarch, goexp string) (flags, baseline goexperiment.Flags, err error) {
+	regabiSupported := false
+
+	baseline = goexperiment.Flags{
+		RegabiWrappers: regabiSupported,
+		RegabiG:        regabiSupported,
+		RegabiReflect:  regabiSupported,
+		RegabiDefer:    regabiSupported,
+		RegabiArgs:     regabiSupported,
+	}
+
+	// Start with the statically enabled set of experiments.
+	flags = baseline
+
+	// Pick up any changes to the baseline configuration from the
+	// GOEXPERIMENT environment. This can be set at make.bash time
+	// and overridden at build time.
+	if goexp != "" {
+		// Create a map of known experiment names.
+		names := make(map[string]func(bool))
+		rv := reflect.ValueOf(&flags).Elem()
+		rt := rv.Type()
+		for i := 0; i < rt.NumField(); i++ {
+			field := rv.Field(i)
+			names[strings.ToLower(rt.Field(i).Name)] = field.SetBool
+		}
+
+		// "regabi" is an alias for all working regabi
+		// subexperiments, and not an experiment itself. Doing
+		// this as an alias make both "regabi" and "noregabi"
+		// do the right thing.
+		names["regabi"] = func(v bool) {
+			flags.RegabiWrappers = v
+			flags.RegabiG = v
+			flags.RegabiReflect = v
+			flags.RegabiDefer = v
+			flags.RegabiArgs = v
+		}
+
+		// Parse names.
+		for _, f := range strings.Split(goexp, ",") {
+			if f == "" {
+				continue
+			}
+			if f == "none" {
+				// GOEXPERIMENT=none disables all experiment flags.
+				// This is used by cmd/dist, which doesn't know how
+				// to build with any experiment flags.
+				flags = goexperiment.Flags{}
+				continue
+			}
+			val := true
+			if strings.HasPrefix(f, "no") {
+				f, val = f[2:], false
+			}
+			set, ok := names[f]
+			if !ok {
+				err = fmt.Errorf("unknown GOEXPERIMENT %s", f)
+				return
+			}
+			set(val)
+		}
+	}
+
+	// regabi is only supported on amd64.
+	if goarch != "amd64" {
+		flags.RegabiWrappers = false
+		flags.RegabiG = false
+		flags.RegabiReflect = false
+		flags.RegabiDefer = false
+		flags.RegabiArgs = false
+	}
+	// Check regabi dependencies.
+	if flags.RegabiG && !flags.RegabiWrappers {
+		err = fmt.Errorf("GOEXPERIMENT regabig requires regabiwrappers")
+	}
+	if flags.RegabiArgs && !(flags.RegabiWrappers && flags.RegabiG && flags.RegabiReflect && flags.RegabiDefer) {
+		err = fmt.Errorf("GOEXPERIMENT regabiargs requires regabiwrappers,regabig,regabireflect,regabidefer")
+	}
+	return
+}
+
+// expList returns the list of lower-cased experiment names for
+// experiments that differ from base. base may be nil to indicate no
+// experiments. If all is true, then include all experiment flags,
+// regardless of base.
+func expList(exp, base *goexperiment.Flags, all bool) []string {
+	var list []string
+	rv := reflect.ValueOf(exp).Elem()
+	var rBase reflect.Value
+	if base != nil {
+		rBase = reflect.ValueOf(base).Elem()
+	}
+	rt := rv.Type()
+	for i := 0; i < rt.NumField(); i++ {
+		name := strings.ToLower(rt.Field(i).Name)
+		val := rv.Field(i).Bool()
+		baseVal := false
+		if base != nil {
+			baseVal = rBase.Field(i).Bool()
+		}
+		if all || val != baseVal {
+			if val {
+				list = append(list, name)
+			} else {
+				list = append(list, "no"+name)
+			}
+		}
+	}
+	return list
+}
+
+// GOEXPERIMENT is a comma-separated list of enabled or disabled
+// experiments that differ from the baseline experiment configuration.
+// GOEXPERIMENT is exactly what a user would set on the command line
+// to get the set of enabled experiments.
+func GOEXPERIMENT() string {
+	return strings.Join(expList(&Experiment, &experimentBaseline, false), ",")
+}
+
+// EnabledExperiments returns a list of enabled experiments, as
+// lower-cased experiment names.
+func EnabledExperiments() []string {
+	return expList(&Experiment, nil, false)
+}
+
+// AllExperiments returns a list of all experiment settings.
+// Disabled experiments appear in the list prefixed by "no".
+func AllExperiments() []string {
+	return expList(&Experiment, nil, true)
+}
+
+// UpdateExperiments updates the Experiment global based on a new GOARCH value.
+// This is only required for cmd/go, which can change GOARCH after
+// program startup due to use of "go env -w".
+func UpdateExperiments(goos, goarch, goexperiment string) {
+	var err error
+	Experiment, experimentBaseline, err = ParseGOEXPERIMENT(goos, goarch, goexperiment)
+	if err != nil {
+		Error = err
+	}
+}
diff --git a/libgo/go/internal/bytealg/bytealg.go b/libgo/go/internal/bytealg/bytealg.go
index 58efb95..68de560 100644
--- a/libgo/go/internal/bytealg/bytealg.go
+++ b/libgo/go/internal/bytealg/bytealg.go
@@ -17,6 +17,8 @@ const (
 	offsetX86HasPOPCNT = unsafe.Offsetof(cpu.X86.HasPOPCNT)
 
 	offsetS390xHasVX = unsafe.Offsetof(cpu.S390X.HasVX)
+
+	offsetPPC64HasPOWER9 = unsafe.Offsetof(cpu.PPC64.IsPOWER9)
 )
 
 // MaxLen is the maximum length of the string to be searched for (argument b) in Index.
diff --git a/libgo/go/internal/bytealg/compare_generic.go b/libgo/go/internal/bytealg/compare_generic.go
index a29e8e7..45e6a02 100644
--- a/libgo/go/internal/bytealg/compare_generic.go
+++ b/libgo/go/internal/bytealg/compare_generic.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build ignore_for_gccgo
-// +build !386,!amd64,!s390x,!arm,!arm64,!ppc64,!ppc64le,!mips,!mipsle,!wasm,!mips64,!mips64le
+//go:build ignore
+// +build ignore
 
 package bytealg
 
diff --git a/libgo/go/internal/bytealg/compare_native.go b/libgo/go/internal/bytealg/compare_native.go
index b189998..629e858 100644
--- a/libgo/go/internal/bytealg/compare_native.go
+++ b/libgo/go/internal/bytealg/compare_native.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//-go:build 386 || amd64 || s390x || arm || arm64 || ppc64 || ppc64le || mips || mipsle || wasm || mips64 || mips64le
 // -build 386 amd64 s390x arm arm64 ppc64 ppc64le mips mipsle wasm mips64 mips64le
 
 package bytealg
diff --git a/libgo/go/internal/bytealg/count_generic.go b/libgo/go/internal/bytealg/count_generic.go
index 7e4510c..d0e1c3b 100644
--- a/libgo/go/internal/bytealg/count_generic.go
+++ b/libgo/go/internal/bytealg/count_generic.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//-go:build !amd64 && !arm && !arm64 && !ppc64le && !ppc64 && !riscv64 && !s390x
 // -build !amd64,!arm,!arm64,!ppc64le,!ppc64,!riscv64,!s390x
 
 package bytealg
diff --git a/libgo/go/internal/bytealg/count_native.go b/libgo/go/internal/bytealg/count_native.go
index a0151a0..efb782f 100644
--- a/libgo/go/internal/bytealg/count_native.go
+++ b/libgo/go/internal/bytealg/count_native.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build ignore_for_gccgo
-// +build amd64 arm arm64 ppc64le ppc64 riscv64 s390x
+//go:build ignore
+// +build ignore
 
 package bytealg
 
diff --git a/libgo/go/internal/bytealg/index_amd64.go b/libgo/go/internal/bytealg/index_amd64.go
index dd6a6cf..7208118 100644
--- a/libgo/go/internal/bytealg/index_amd64.go
+++ b/libgo/go/internal/bytealg/index_amd64.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ignore_for_gccgo
 // +build ignore_for_gccgo
 
 package bytealg
diff --git a/libgo/go/internal/bytealg/index_generic.go b/libgo/go/internal/bytealg/index_generic.go
index c595c23..a880eb3 100644
--- a/libgo/go/internal/bytealg/index_generic.go
+++ b/libgo/go/internal/bytealg/index_generic.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build ignore_for_gccgo
-// +build !amd64,!arm64,!s390x
+//go:build ignore
+// +build ignore
 
 package bytealg
 
diff --git a/libgo/go/internal/bytealg/index_native.go b/libgo/go/internal/bytealg/index_native.go
index 26f4769..7086940 100644
--- a/libgo/go/internal/bytealg/index_native.go
+++ b/libgo/go/internal/bytealg/index_native.go
@@ -2,7 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// -build amd64 arm64 s390x
+//-go:build amd64 || arm64 || s390x || ppc64le || ppc64
+// -build amd64 arm64 s390x ppc64le ppc64
 
 package bytealg
 
diff --git a/libgo/go/internal/bytealg/index_ppc64x.go b/libgo/go/internal/bytealg/index_ppc64x.go
new file mode 100644
index 0000000..f8f8f50
--- /dev/null
+++ b/libgo/go/internal/bytealg/index_ppc64x.go
@@ -0,0 +1,27 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ignore_for_gccgo
+// +build ignore_for_gccgo
+
+package bytealg
+
+import "internal/cpu"
+
+const MaxBruteForce = 16
+
+var SupportsPower9 = cpu.PPC64.IsPOWER9
+
+func init() {
+	MaxLen = 32
+}
+
+// Cutover reports the number of failures of IndexByte we should tolerate
+// before switching over to Index.
+// n is the number of bytes processed so far.
+// See the bytes.Index implementation for details.
+func Cutover(n int) int {
+	// 1 error per 8 characters, plus a few slop to start.
+	return (n + 16) / 8
+}
diff --git a/libgo/go/internal/bytealg/indexbyte_generic.go b/libgo/go/internal/bytealg/indexbyte_generic.go
index 46325dd..09a6615 100644
--- a/libgo/go/internal/bytealg/indexbyte_generic.go
+++ b/libgo/go/internal/bytealg/indexbyte_generic.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build ignore_for_gccgo
-// +build !386,!amd64,!s390x,!arm,!arm64,!ppc64,!ppc64le,!mips,!mipsle,!mips64,!mips64le,!riscv,!riscv64,!wasm
+//go:build ignore
+// +build ignore
 
 package bytealg
 
diff --git a/libgo/go/internal/bytealg/indexbyte_native.go b/libgo/go/internal/bytealg/indexbyte_native.go
index c427e66..2cc118c 100644
--- a/libgo/go/internal/bytealg/indexbyte_native.go
+++ b/libgo/go/internal/bytealg/indexbyte_native.go
@@ -2,7 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// -build 386 amd64 s390x arm arm64 ppc64 ppc64le mips mipsle mips64 mips64le riscv riscv64 wasm
+//-go:build 386 || amd64 || s390x || arm || arm64 || ppc64 || ppc64le || mips || mipsle || mips64 || mips64le || riscv64 || wasm
+// -build 386 amd64 s390x arm arm64 ppc64 ppc64le mips mipsle mips64 mips64le riscv64 wasm
 
 package bytealg
 
diff --git a/libgo/go/internal/cfg/cfg.go b/libgo/go/internal/cfg/cfg.go
index 5530213..815994b 100644
--- a/libgo/go/internal/cfg/cfg.go
+++ b/libgo/go/internal/cfg/cfg.go
@@ -39,6 +39,7 @@ const KnownEnv = `
 	GOCACHE
 	GOENV
 	GOEXE
+	GOEXPERIMENT
 	GOFLAGS
 	GOGCCFLAGS
 	GOHOSTARCH
diff --git a/libgo/go/internal/cpu/cpu_arm64_android.go b/libgo/go/internal/cpu/cpu_arm64_android.go
index 3c9e57c..ac6eee5 100644
--- a/libgo/go/internal/cpu/cpu_arm64_android.go
+++ b/libgo/go/internal/cpu/cpu_arm64_android.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build arm64
 // +build arm64
 
 package cpu
diff --git a/libgo/go/internal/cpu/cpu_arm64_darwin.go b/libgo/go/internal/cpu/cpu_arm64_darwin.go
index e094b97..ce1b250 100644
--- a/libgo/go/internal/cpu/cpu_arm64_darwin.go
+++ b/libgo/go/internal/cpu/cpu_arm64_darwin.go
@@ -2,9 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build arm64
-// +build darwin
-// +build !ios
+//go:build arm64 && darwin && !ios
+// +build arm64,darwin,!ios
 
 package cpu
 
diff --git a/libgo/go/internal/cpu/cpu_arm64_freebsd.go b/libgo/go/internal/cpu/cpu_arm64_freebsd.go
index 9de2005..8c48137 100644
--- a/libgo/go/internal/cpu/cpu_arm64_freebsd.go
+++ b/libgo/go/internal/cpu/cpu_arm64_freebsd.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build arm64
 // +build arm64
 
 package cpu
diff --git a/libgo/go/internal/cpu/cpu_arm64_hwcap.go b/libgo/go/internal/cpu/cpu_arm64_hwcap.go
index fdaf43e..8ac04fd 100644
--- a/libgo/go/internal/cpu/cpu_arm64_hwcap.go
+++ b/libgo/go/internal/cpu/cpu_arm64_hwcap.go
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build arm64
-// +build linux
+//go:build arm64 && linux
+// +build arm64,linux
 
 package cpu
 
diff --git a/libgo/go/internal/cpu/cpu_arm64_linux.go b/libgo/go/internal/cpu/cpu_arm64_linux.go
index 2f7411f..c3a3f9a 100644
--- a/libgo/go/internal/cpu/cpu_arm64_linux.go
+++ b/libgo/go/internal/cpu/cpu_arm64_linux.go
@@ -2,9 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build arm64
-// +build linux
-// +build !android
+//go:build arm64 && linux && !android
+// +build arm64,linux,!android
 
 package cpu
 
diff --git a/libgo/go/internal/cpu/cpu_arm64_other.go b/libgo/go/internal/cpu/cpu_arm64_other.go
index f191db2..e8b5d529 100644
--- a/libgo/go/internal/cpu/cpu_arm64_other.go
+++ b/libgo/go/internal/cpu/cpu_arm64_other.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build arm64 && !linux && !freebsd && !android && (!darwin || ios)
 // +build arm64
 // +build !linux
 // +build !freebsd
diff --git a/libgo/go/internal/cpu/cpu_mips64x.go b/libgo/go/internal/cpu/cpu_mips64x.go
index 58fbd3d..c660403 100644
--- a/libgo/go/internal/cpu/cpu_mips64x.go
+++ b/libgo/go/internal/cpu/cpu_mips64x.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips64 || mips64le
 // +build mips64 mips64le
 
 package cpu
diff --git a/libgo/go/internal/cpu/cpu_no_name.go b/libgo/go/internal/cpu/cpu_no_name.go
index f028a92..8e636d5 100644
--- a/libgo/go/internal/cpu/cpu_no_name.go
+++ b/libgo/go/internal/cpu/cpu_no_name.go
@@ -2,9 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !386
-// +build !amd64
-// +build !amd64p32
+//go:build !386 && !amd64 && !amd64p32
+// +build !386,!amd64,!amd64p32
 
 package cpu
 
diff --git a/libgo/go/internal/cpu/cpu_ppc64x.go b/libgo/go/internal/cpu/cpu_ppc64x.go
index 0a48f6a..1c7c39f 100644
--- a/libgo/go/internal/cpu/cpu_ppc64x.go
+++ b/libgo/go/internal/cpu/cpu_ppc64x.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ppc || ppc64 || ppc64le
 // +build ppc ppc64 ppc64le
 
 package cpu
diff --git a/libgo/go/internal/cpu/cpu_ppc64x_aix.go b/libgo/go/internal/cpu/cpu_ppc64x_aix.go
index e2422a6..c7e47b2 100644
--- a/libgo/go/internal/cpu/cpu_ppc64x_aix.go
+++ b/libgo/go/internal/cpu/cpu_ppc64x_aix.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ppc || ppc64 || ppc64le
 // +build ppc ppc64 ppc64le
 
 package cpu
diff --git a/libgo/go/internal/cpu/cpu_ppc64x_linux.go b/libgo/go/internal/cpu/cpu_ppc64x_linux.go
index 068a799..0c89f3b 100644
--- a/libgo/go/internal/cpu/cpu_ppc64x_linux.go
+++ b/libgo/go/internal/cpu/cpu_ppc64x_linux.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ppc || ppc64 || ppc64le
 // +build ppc ppc64 ppc64le
 
 package cpu
diff --git a/libgo/go/internal/cpu/cpu_x86.go b/libgo/go/internal/cpu/cpu_x86.go
index 338d909..6182532 100644
--- a/libgo/go/internal/cpu/cpu_x86.go
+++ b/libgo/go/internal/cpu/cpu_x86.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build 386 || amd64 || amd64p32
 // +build 386 amd64 amd64p32
 
 package cpu
diff --git a/libgo/go/internal/cpu/cpu_x86_test.go b/libgo/go/internal/cpu/cpu_x86_test.go
index 61db93b..e3e16cc 100644
--- a/libgo/go/internal/cpu/cpu_x86_test.go
+++ b/libgo/go/internal/cpu/cpu_x86_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build 386 || amd64
 // +build 386 amd64
 
 package cpu_test
diff --git a/libgo/go/internal/execabs/execabs_test.go b/libgo/go/internal/execabs/execabs_test.go
index b714585..97a3f39 100644
--- a/libgo/go/internal/execabs/execabs_test.go
+++ b/libgo/go/internal/execabs/execabs_test.go
@@ -8,7 +8,6 @@ import (
 	"context"
 	"fmt"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -42,8 +41,8 @@ func TestCommand(t *testing.T) {
 		if runtime.GOOS == "windows" {
 			executable += ".exe"
 		}
-		if err := ioutil.WriteFile(filepath.Join(tmpDir, executable), []byte{1, 2, 3}, 0111); err != nil {
-			t.Fatalf("ioutil.WriteFile failed: %s", err)
+		if err := os.WriteFile(filepath.Join(tmpDir, executable), []byte{1, 2, 3}, 0111); err != nil {
+			t.Fatalf("os.WriteFile failed: %s", err)
 		}
 		cwd, err := os.Getwd()
 		if err != nil {
@@ -77,8 +76,8 @@ func TestLookPath(t *testing.T) {
 	if runtime.GOOS == "windows" {
 		executable += ".exe"
 	}
-	if err := ioutil.WriteFile(filepath.Join(tmpDir, executable), []byte{1, 2, 3}, 0111); err != nil {
-		t.Fatalf("ioutil.WriteFile failed: %s", err)
+	if err := os.WriteFile(filepath.Join(tmpDir, executable), []byte{1, 2, 3}, 0111); err != nil {
+		t.Fatalf("os.WriteFile failed: %s", err)
 	}
 	cwd, err := os.Getwd()
 	if err != nil {
diff --git a/libgo/go/internal/goexperiment/exp_fieldtrack_off.go b/libgo/go/internal/goexperiment/exp_fieldtrack_off.go
new file mode 100644
index 0000000..e5e1326
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_fieldtrack_off.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build !goexperiment.fieldtrack
+// +build !goexperiment.fieldtrack
+
+package goexperiment
+
+const FieldTrack = false
+const FieldTrackInt = 0
diff --git a/libgo/go/internal/goexperiment/exp_fieldtrack_on.go b/libgo/go/internal/goexperiment/exp_fieldtrack_on.go
new file mode 100644
index 0000000..0d8c447
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_fieldtrack_on.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build goexperiment.fieldtrack
+// +build goexperiment.fieldtrack
+
+package goexperiment
+
+const FieldTrack = true
+const FieldTrackInt = 1
diff --git a/libgo/go/internal/goexperiment/exp_preemptibleloops_off.go b/libgo/go/internal/goexperiment/exp_preemptibleloops_off.go
new file mode 100644
index 0000000..7a26088
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_preemptibleloops_off.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build !goexperiment.preemptibleloops
+// +build !goexperiment.preemptibleloops
+
+package goexperiment
+
+const PreemptibleLoops = false
+const PreemptibleLoopsInt = 0
diff --git a/libgo/go/internal/goexperiment/exp_preemptibleloops_on.go b/libgo/go/internal/goexperiment/exp_preemptibleloops_on.go
new file mode 100644
index 0000000..a9ca28c
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_preemptibleloops_on.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build goexperiment.preemptibleloops
+// +build goexperiment.preemptibleloops
+
+package goexperiment
+
+const PreemptibleLoops = true
+const PreemptibleLoopsInt = 1
diff --git a/libgo/go/internal/goexperiment/exp_regabi_off.go b/libgo/go/internal/goexperiment/exp_regabi_off.go
new file mode 100644
index 0000000..5d88238
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_regabi_off.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build !goexperiment.regabi
+// +build !goexperiment.regabi
+
+package goexperiment
+
+const Regabi = false
+const RegabiInt = 0
diff --git a/libgo/go/internal/goexperiment/exp_regabi_on.go b/libgo/go/internal/goexperiment/exp_regabi_on.go
new file mode 100644
index 0000000..c08d58e
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_regabi_on.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build goexperiment.regabi
+// +build goexperiment.regabi
+
+package goexperiment
+
+const Regabi = true
+const RegabiInt = 1
diff --git a/libgo/go/internal/goexperiment/exp_regabiargs_off.go b/libgo/go/internal/goexperiment/exp_regabiargs_off.go
new file mode 100644
index 0000000..31a139b
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_regabiargs_off.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build !goexperiment.regabiargs
+// +build !goexperiment.regabiargs
+
+package goexperiment
+
+const RegabiArgs = false
+const RegabiArgsInt = 0
diff --git a/libgo/go/internal/goexperiment/exp_regabiargs_on.go b/libgo/go/internal/goexperiment/exp_regabiargs_on.go
new file mode 100644
index 0000000..9b26f3c
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_regabiargs_on.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build goexperiment.regabiargs
+// +build goexperiment.regabiargs
+
+package goexperiment
+
+const RegabiArgs = true
+const RegabiArgsInt = 1
diff --git a/libgo/go/internal/goexperiment/exp_regabidefer_off.go b/libgo/go/internal/goexperiment/exp_regabidefer_off.go
new file mode 100644
index 0000000..b47c0c2
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_regabidefer_off.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build !goexperiment.regabidefer
+// +build !goexperiment.regabidefer
+
+package goexperiment
+
+const RegabiDefer = false
+const RegabiDeferInt = 0
diff --git a/libgo/go/internal/goexperiment/exp_regabidefer_on.go b/libgo/go/internal/goexperiment/exp_regabidefer_on.go
new file mode 100644
index 0000000..bbf2f6c
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_regabidefer_on.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build goexperiment.regabidefer
+// +build goexperiment.regabidefer
+
+package goexperiment
+
+const RegabiDefer = true
+const RegabiDeferInt = 1
diff --git a/libgo/go/internal/goexperiment/exp_regabig_off.go b/libgo/go/internal/goexperiment/exp_regabig_off.go
new file mode 100644
index 0000000..1b37d45
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_regabig_off.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build !goexperiment.regabig
+// +build !goexperiment.regabig
+
+package goexperiment
+
+const RegabiG = false
+const RegabiGInt = 0
diff --git a/libgo/go/internal/goexperiment/exp_regabig_on.go b/libgo/go/internal/goexperiment/exp_regabig_on.go
new file mode 100644
index 0000000..7e5b162
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_regabig_on.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build goexperiment.regabig
+// +build goexperiment.regabig
+
+package goexperiment
+
+const RegabiG = true
+const RegabiGInt = 1
diff --git a/libgo/go/internal/goexperiment/exp_regabireflect_off.go b/libgo/go/internal/goexperiment/exp_regabireflect_off.go
new file mode 100644
index 0000000..515f4a5
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_regabireflect_off.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build !goexperiment.regabireflect
+// +build !goexperiment.regabireflect
+
+package goexperiment
+
+const RegabiReflect = false
+const RegabiReflectInt = 0
diff --git a/libgo/go/internal/goexperiment/exp_regabireflect_on.go b/libgo/go/internal/goexperiment/exp_regabireflect_on.go
new file mode 100644
index 0000000..e8a3e9c
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_regabireflect_on.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build goexperiment.regabireflect
+// +build goexperiment.regabireflect
+
+package goexperiment
+
+const RegabiReflect = true
+const RegabiReflectInt = 1
diff --git a/libgo/go/internal/goexperiment/exp_regabiwrappers_off.go b/libgo/go/internal/goexperiment/exp_regabiwrappers_off.go
new file mode 100644
index 0000000..bfa0fa3
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_regabiwrappers_off.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build !goexperiment.regabiwrappers
+// +build !goexperiment.regabiwrappers
+
+package goexperiment
+
+const RegabiWrappers = false
+const RegabiWrappersInt = 0
diff --git a/libgo/go/internal/goexperiment/exp_regabiwrappers_on.go b/libgo/go/internal/goexperiment/exp_regabiwrappers_on.go
new file mode 100644
index 0000000..11ffffb
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_regabiwrappers_on.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build goexperiment.regabiwrappers
+// +build goexperiment.regabiwrappers
+
+package goexperiment
+
+const RegabiWrappers = true
+const RegabiWrappersInt = 1
diff --git a/libgo/go/internal/goexperiment/exp_staticlockranking_off.go b/libgo/go/internal/goexperiment/exp_staticlockranking_off.go
new file mode 100644
index 0000000..3d546c0
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_staticlockranking_off.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build !goexperiment.staticlockranking
+// +build !goexperiment.staticlockranking
+
+package goexperiment
+
+const StaticLockRanking = false
+const StaticLockRankingInt = 0
diff --git a/libgo/go/internal/goexperiment/exp_staticlockranking_on.go b/libgo/go/internal/goexperiment/exp_staticlockranking_on.go
new file mode 100644
index 0000000..78188fb
--- /dev/null
+++ b/libgo/go/internal/goexperiment/exp_staticlockranking_on.go
@@ -0,0 +1,9 @@
+// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build goexperiment.staticlockranking
+// +build goexperiment.staticlockranking
+
+package goexperiment
+
+const StaticLockRanking = true
+const StaticLockRankingInt = 1
diff --git a/libgo/go/internal/goexperiment/flags.go b/libgo/go/internal/goexperiment/flags.go
new file mode 100644
index 0000000..cd4c178
--- /dev/null
+++ b/libgo/go/internal/goexperiment/flags.go
@@ -0,0 +1,93 @@
+// Copyright 2021 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 goexperiment implements support for toolchain experiments.
+//
+// Toolchain experiments are controlled by the GOEXPERIMENT
+// environment variable. GOEXPERIMENT is a comma-separated list of
+// experiment names. GOEXPERIMENT can be set at make.bash time, which
+// sets the default experiments for binaries built with the tool
+// chain; or it can be set at build time. GOEXPERIMENT can also be set
+// to "none", which disables any experiments that were enabled at
+// make.bash time.
+//
+// Experiments are exposed to the build in the following ways:
+//
+// - Build tag goexperiment.x is set if experiment x (lower case) is
+// enabled.
+//
+// - For each experiment x (in camel case), this package contains a
+// boolean constant x and an integer constant xInt.
+//
+// - In runtime assembly, the macro GOEXPERIMENT_x is defined if
+// experiment x (lower case) is enabled.
+//
+// In the toolchain, the set of experiments enabled for the current
+// build should be accessed via objabi.Experiment.
+//
+// The set of experiments is included in the output of runtime.Version()
+// and "go version <binary>" if it differs from the default experiments.
+//
+// For the set of experiments supported by the current toolchain, see
+// "go doc goexperiment.Flags".
+//
+// Note that this package defines the set of experiments (in Flags)
+// and records the experiments that were enabled when the package
+// was compiled (as boolean and integer constants).
+//
+// Note especially that this package does not itself change behavior
+// at run time based on the GOEXPERIMENT variable.
+// The code used in builds to interpret the GOEXPERIMENT variable
+// is in the separate package internal/buildcfg.
+package goexperiment
+
+//go:generate go run mkconsts.go
+
+// Flags is the set of experiments that can be enabled or disabled in
+// the current toolchain.
+//
+// When specified in the GOEXPERIMENT environment variable or as build
+// tags, experiments use the strings.ToLower of their field name.
+//
+// For the baseline experimental configuration, see
+// objabi.experimentBaseline.
+//
+// If you change this struct definition, run "go generate".
+type Flags struct {
+	FieldTrack        bool
+	PreemptibleLoops  bool
+	StaticLockRanking bool
+
+	// Regabi is split into several sub-experiments that can be
+	// enabled individually. Not all combinations work.
+	// The "regabi" GOEXPERIMENT is an alias for all "working"
+	// subexperiments.
+
+	// RegabiWrappers enables ABI wrappers for calling between
+	// ABI0 and ABIInternal functions. Without this, the ABIs are
+	// assumed to be identical so cross-ABI calls are direct.
+	RegabiWrappers bool
+	// RegabiG enables dedicated G and zero registers in
+	// ABIInternal.
+	//
+	// Requires wrappers because it makes the ABIs incompatible.
+	RegabiG bool
+	// RegabiReflect enables the register-passing paths in
+	// reflection calls. This is also gated by intArgRegs in
+	// reflect and runtime (which are disabled by default) so it
+	// can be used in targeted tests.
+	RegabiReflect bool
+	// RegabiDefer enables desugaring defer and go calls
+	// into argument-less closures.
+	RegabiDefer bool
+	// RegabiArgs enables register arguments/results in all
+	// compiled Go functions.
+	//
+	// Requires wrappers (to do ABI translation), g (because
+	// runtime assembly that's been ported to ABIInternal uses the
+	// G register), reflect (so reflection calls use registers),
+	// and defer (because the runtime doesn't support passing
+	// register arguments to defer/go).
+	RegabiArgs bool
+}
diff --git a/libgo/go/internal/goexperiment/mkconsts.go b/libgo/go/internal/goexperiment/mkconsts.go
new file mode 100644
index 0000000..204ca9d
--- /dev/null
+++ b/libgo/go/internal/goexperiment/mkconsts.go
@@ -0,0 +1,74 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ignore
+// +build ignore
+
+// mkconsts generates const definition files for each GOEXPERIMENT.
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"internal/goexperiment"
+	"log"
+	"os"
+	"reflect"
+	"strings"
+)
+
+func main() {
+	// Delete existing experiment constant files.
+	ents, err := os.ReadDir(".")
+	if err != nil {
+		log.Fatal(err)
+	}
+	for _, ent := range ents {
+		name := ent.Name()
+		if !strings.HasPrefix(name, "exp_") {
+			continue
+		}
+		// Check that this is definitely a generated file.
+		data, err := os.ReadFile(name)
+		if err != nil {
+			log.Fatalf("reading %s: %v", name, err)
+		}
+		if !bytes.Contains(data, []byte("Code generated by mkconsts")) {
+			log.Fatalf("%s: expected generated file", name)
+		}
+		if err := os.Remove(name); err != nil {
+			log.Fatal(err)
+		}
+	}
+
+	// Generate new experiment constant files.
+	rt := reflect.TypeOf(&goexperiment.Flags{}).Elem()
+	for i := 0; i < rt.NumField(); i++ {
+		f := rt.Field(i).Name
+		buildTag := "goexperiment." + strings.ToLower(f)
+		for _, val := range []bool{false, true} {
+			name := fmt.Sprintf("exp_%s_%s.go", strings.ToLower(f), pick(val, "off", "on"))
+			data := fmt.Sprintf(`// Code generated by mkconsts.go. DO NOT EDIT.
+
+//go:build %s%s
+// +build %s%s
+
+package goexperiment
+
+const %s = %v
+const %sInt = %s
+`, pick(val, "!", ""), buildTag, pick(val, "!", ""), buildTag, f, val, f, pick(val, "0", "1"))
+			if err := os.WriteFile(name, []byte(data), 0666); err != nil {
+				log.Fatalf("writing %s: %v", name, err)
+			}
+		}
+	}
+}
+
+func pick(v bool, f, t string) string {
+	if v {
+		return t
+	}
+	return f
+}
diff --git a/libgo/go/internal/goroot/gc.go b/libgo/go/internal/goroot/gc.go
index ce72bc3..2338b78 100644
--- a/libgo/go/internal/goroot/gc.go
+++ b/libgo/go/internal/goroot/gc.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build gc
 // +build gc
 
 package goroot
diff --git a/libgo/go/internal/goroot/gccgo.go b/libgo/go/internal/goroot/gccgo.go
index 3530e59..b1041da 100644
--- a/libgo/go/internal/goroot/gccgo.go
+++ b/libgo/go/internal/goroot/gccgo.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build gccgo
 // +build gccgo
 
 package goroot
diff --git a/libgo/go/internal/goversion/goversion.go b/libgo/go/internal/goversion/goversion.go
index 513be45..4cc1568 100644
--- a/libgo/go/internal/goversion/goversion.go
+++ b/libgo/go/internal/goversion/goversion.go
@@ -9,4 +9,4 @@ package goversion
 //
 // It should be updated at the start of each development cycle to be
 // the version of the next Go 1.x release. See golang.org/issue/40705.
-const Version = 16
+const Version = 17
diff --git a/libgo/go/internal/itoa/itoa.go b/libgo/go/internal/itoa/itoa.go
new file mode 100644
index 0000000..c6062d9
--- /dev/null
+++ b/libgo/go/internal/itoa/itoa.go
@@ -0,0 +1,33 @@
+// Copyright 2021 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.
+
+// Simple conversions to avoid depending on strconv.
+
+package itoa
+
+// Itoa converts val to a decimal string.
+func Itoa(val int) string {
+	if val < 0 {
+		return "-" + Uitoa(uint(-val))
+	}
+	return Uitoa(uint(val))
+}
+
+// Uitoa converts val to a decimal string.
+func Uitoa(val uint) string {
+	if val == 0 { // avoid string allocation
+		return "0"
+	}
+	var buf [20]byte // big enough for 64bit value base 10
+	i := len(buf) - 1
+	for val >= 10 {
+		q := val / 10
+		buf[i] = byte('0' + val - q*10)
+		i--
+		val = q
+	}
+	// val < 10
+	buf[i] = byte('0' + val)
+	return string(buf[i:])
+}
diff --git a/libgo/go/internal/itoa/itoa_test.go b/libgo/go/internal/itoa/itoa_test.go
new file mode 100644
index 0000000..71931c1
--- /dev/null
+++ b/libgo/go/internal/itoa/itoa_test.go
@@ -0,0 +1,40 @@
+// Copyright 2021 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 itoa_test
+
+import (
+	"fmt"
+	"internal/itoa"
+	"math"
+	"testing"
+)
+
+var (
+	minInt64  int64  = math.MinInt64
+	maxInt64  int64  = math.MaxInt64
+	maxUint64 uint64 = math.MaxUint64
+)
+
+func TestItoa(t *testing.T) {
+	tests := []int{int(minInt64), math.MinInt32, -999, -100, -1, 0, 1, 100, 999, math.MaxInt32, int(maxInt64)}
+	for _, tt := range tests {
+		got := itoa.Itoa(tt)
+		want := fmt.Sprint(tt)
+		if want != got {
+			t.Fatalf("Itoa(%d) = %s, want %s", tt, got, want)
+		}
+	}
+}
+
+func TestUitoa(t *testing.T) {
+	tests := []uint{0, 1, 100, 999, math.MaxUint32, uint(maxUint64)}
+	for _, tt := range tests {
+		got := itoa.Uitoa(tt)
+		want := fmt.Sprint(tt)
+		if want != got {
+			t.Fatalf("Uitoa(%d) = %s, want %s", tt, got, want)
+		}
+	}
+}
diff --git a/libgo/go/internal/poll/copy_file_range_linux.go b/libgo/go/internal/poll/copy_file_range_linux.go
index 01b242a..5b9e5d4 100644
--- a/libgo/go/internal/poll/copy_file_range_linux.go
+++ b/libgo/go/internal/poll/copy_file_range_linux.go
@@ -78,7 +78,7 @@ func CopyFileRange(dst, src *FD, remain int64) (written int64, handled bool, err
 			// Go supports Linux >= 2.6.33, so the system call
 			// may not be present.
 			//
-			// If we see ENOSYS, we have certainly not transfered
+			// If we see ENOSYS, we have certainly not transferred
 			// any data, so we can tell the caller that we
 			// couldn't handle the transfer and let them fall
 			// back to more generic code.
@@ -91,13 +91,13 @@ func CopyFileRange(dst, src *FD, remain int64) (written int64, handled bool, err
 			// Prior to Linux 5.3, it was not possible to
 			// copy_file_range across file systems. Similarly to
 			// the ENOSYS case above, if we see EXDEV, we have
-			// not transfered any data, and we can let the caller
+			// not transferred any data, and we can let the caller
 			// fall back to generic code.
 			//
 			// As for EINVAL, that is what we see if, for example,
 			// dst or src refer to a pipe rather than a regular
 			// file. This is another case where no data has been
-			// transfered, so we consider it unhandled.
+			// transferred, so we consider it unhandled.
 			//
 			// If src and dst are on CIFS, we can see EIO.
 			// See issue #42334.
diff --git a/libgo/go/internal/poll/errno_unix.go b/libgo/go/internal/poll/errno_unix.go
index 922230b..d03a2d2 100644
--- a/libgo/go/internal/poll/errno_unix.go
+++ b/libgo/go/internal/poll/errno_unix.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || hurd || linux || netbsd || openbsd || solaris
 // +build aix darwin dragonfly freebsd hurd linux netbsd openbsd solaris
 
 package poll
diff --git a/libgo/go/internal/poll/errno_windows.go b/libgo/go/internal/poll/errno_windows.go
index e3bddb4..c55f5f0 100644
--- a/libgo/go/internal/poll/errno_windows.go
+++ b/libgo/go/internal/poll/errno_windows.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build windows
 // +build windows
 
 package poll
diff --git a/libgo/go/internal/poll/error_stub_test.go b/libgo/go/internal/poll/error_stub_test.go
index c40ffcd..bcc25dd 100644
--- a/libgo/go/internal/poll/error_stub_test.go
+++ b/libgo/go/internal/poll/error_stub_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !linux
 // +build !linux
 
 package poll_test
diff --git a/libgo/go/internal/poll/export_linux_test.go b/libgo/go/internal/poll/export_linux_test.go
new file mode 100644
index 0000000..7fba793
--- /dev/null
+++ b/libgo/go/internal/poll/export_linux_test.go
@@ -0,0 +1,22 @@
+// Copyright 2021 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.
+
+// Export guts for testing on linux.
+// Since testing imports os and os imports internal/poll,
+// the internal/poll tests can not be in package poll.
+
+package poll
+
+var (
+	GetPipe     = getPipe
+	PutPipe     = putPipe
+	NewPipe     = newPipe
+	DestroyPipe = destroyPipe
+)
+
+func GetPipeFds(p *SplicePipe) (int, int) {
+	return p.rfd, p.wfd
+}
+
+type SplicePipe = splicePipe
diff --git a/libgo/go/internal/poll/export_posix_test.go b/libgo/go/internal/poll/export_posix_test.go
index 8ab4fd6..1e714cd 100644
--- a/libgo/go/internal/poll/export_posix_test.go
+++ b/libgo/go/internal/poll/export_posix_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || hurd || linux || netbsd || openbsd || solaris || windows
 // +build aix darwin dragonfly freebsd hurd linux netbsd openbsd solaris windows
 
 // Export guts for testing on posix.
diff --git a/libgo/go/internal/poll/export_test.go b/libgo/go/internal/poll/export_test.go
index 02664d9..e1125cb 100644
--- a/libgo/go/internal/poll/export_test.go
+++ b/libgo/go/internal/poll/export_test.go
@@ -33,3 +33,5 @@ func (mu *FDMutex) RWLock(read bool) bool {
 func (mu *FDMutex) RWUnlock(read bool) bool {
 	return mu.rwunlock(read)
 }
+
+var Fcntl = fcntl
diff --git a/libgo/go/internal/poll/fcntl_js.go b/libgo/go/internal/poll/fcntl_js.go
index 120fc11..7bf0ddc 100644
--- a/libgo/go/internal/poll/fcntl_js.go
+++ b/libgo/go/internal/poll/fcntl_js.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build js && wasm
 // +build js,wasm
 
 package poll
diff --git a/libgo/go/internal/poll/fcntl_libc.go b/libgo/go/internal/poll/fcntl_libc.go
index ed00f76..e9a98e3 100644
--- a/libgo/go/internal/poll/fcntl_libc.go
+++ b/libgo/go/internal/poll/fcntl_libc.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || solaris
 // +build aix darwin solaris
 
 package poll
diff --git a/libgo/go/internal/poll/fcntl_syscall.go b/libgo/go/internal/poll/fcntl_syscall.go
index fb82b9b..cd0061f 100644
--- a/libgo/go/internal/poll/fcntl_syscall.go
+++ b/libgo/go/internal/poll/fcntl_syscall.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build dragonfly || freebsd || hurd || linux || netbsd || openbsd
 // +build dragonfly freebsd hurd linux netbsd openbsd
 
 package poll
diff --git a/libgo/go/internal/poll/fd.go b/libgo/go/internal/poll/fd.go
index b72ea3d..69a9005 100644
--- a/libgo/go/internal/poll/fd.go
+++ b/libgo/go/internal/poll/fd.go
@@ -13,11 +13,22 @@ import (
 	"errors"
 )
 
-// ErrNetClosing is returned when a network descriptor is used after
-// it has been closed. Keep this string consistent because of issue
-// #4373: since historically programs have not been able to detect
+// errNetClosing is the type of the variable ErrNetClosing.
+// This is used to implement the net.Error interface.
+type errNetClosing struct{}
+
+// Error returns the error message for ErrNetClosing.
+// Keep this string consistent because of issue #4373:
+// since historically programs have not been able to detect
 // this error, they look for the string.
-var ErrNetClosing = errors.New("use of closed network connection")
+func (e errNetClosing) Error() string { return "use of closed network connection" }
+
+func (e errNetClosing) Timeout() bool   { return false }
+func (e errNetClosing) Temporary() bool { return false }
+
+// ErrNetClosing is returned when a network descriptor is used after
+// it has been closed.
+var ErrNetClosing = errNetClosing{}
 
 // ErrFileClosing is returned when a file descriptor is used after it
 // has been closed.
diff --git a/libgo/go/internal/poll/fd_fsync_posix.go b/libgo/go/internal/poll/fd_fsync_posix.go
index 9be0f54..21f1de4 100644
--- a/libgo/go/internal/poll/fd_fsync_posix.go
+++ b/libgo/go/internal/poll/fd_fsync_posix.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || dragonfly || freebsd || hurd || (js && wasm) || linux || netbsd || openbsd || solaris
 // +build aix dragonfly freebsd hurd js,wasm linux netbsd openbsd solaris
 
 package poll
diff --git a/libgo/go/internal/poll/fd_io_plan9.go b/libgo/go/internal/poll/fd_io_plan9.go
index 287d11b..3205ac8 100644
--- a/libgo/go/internal/poll/fd_io_plan9.go
+++ b/libgo/go/internal/poll/fd_io_plan9.go
@@ -5,6 +5,7 @@
 package poll
 
 import (
+	"internal/itoa"
 	"runtime"
 	"sync"
 	"syscall"
@@ -71,7 +72,7 @@ func (aio *asyncIO) Cancel() {
 	if aio.pid == -1 {
 		return
 	}
-	f, e := syscall.Open("/proc/"+itoa(aio.pid)+"/note", syscall.O_WRONLY)
+	f, e := syscall.Open("/proc/"+itoa.Itoa(aio.pid)+"/note", syscall.O_WRONLY)
 	if e != nil {
 		return
 	}
diff --git a/libgo/go/internal/poll/fd_poll_js.go b/libgo/go/internal/poll/fd_poll_js.go
index d6b28e5..760e248 100644
--- a/libgo/go/internal/poll/fd_poll_js.go
+++ b/libgo/go/internal/poll/fd_poll_js.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build js && wasm
 // +build js,wasm
 
 package poll
diff --git a/libgo/go/internal/poll/fd_poll_runtime.go b/libgo/go/internal/poll/fd_poll_runtime.go
index 55aa304..f40b845 100644
--- a/libgo/go/internal/poll/fd_poll_runtime.go
+++ b/libgo/go/internal/poll/fd_poll_runtime.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || hurd || linux || netbsd || openbsd || windows || solaris
 // +build aix darwin dragonfly freebsd hurd linux netbsd openbsd windows solaris
 
 package poll
@@ -38,10 +39,6 @@ func (pd *pollDesc) init(fd *FD) error {
 	serverInit.Do(runtime_pollServerInit)
 	ctx, errno := runtime_pollOpen(uintptr(fd.Sysfd))
 	if errno != 0 {
-		if ctx != 0 {
-			runtime_pollUnblock(ctx)
-			runtime_pollClose(ctx)
-		}
 		return errnoErr(syscall.Errno(errno))
 	}
 	pd.runtimeCtx = ctx
diff --git a/libgo/go/internal/poll/fd_posix.go b/libgo/go/internal/poll/fd_posix.go
index 16c2e50..fd64e53 100644
--- a/libgo/go/internal/poll/fd_posix.go
+++ b/libgo/go/internal/poll/fd_posix.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || hurd || (js && wasm) || linux || netbsd || openbsd || solaris || windows
 // +build aix darwin dragonfly freebsd hurd js,wasm linux netbsd openbsd solaris windows
 
 package poll
diff --git a/libgo/go/internal/poll/fd_posix_test.go b/libgo/go/internal/poll/fd_posix_test.go
index dfcfd5c..1dc3f0f 100644
--- a/libgo/go/internal/poll/fd_posix_test.go
+++ b/libgo/go/internal/poll/fd_posix_test.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || hurd || linux || netbsd || openbsd || solaris || windows
 // +build aix darwin dragonfly freebsd hurd linux netbsd openbsd solaris windows
 
 package poll_test
diff --git a/libgo/go/internal/poll/fd_unix.go b/libgo/go/internal/poll/fd_unix.go
index 013b7e5..d8861de 100644
--- a/libgo/go/internal/poll/fd_unix.go
+++ b/libgo/go/internal/poll/fd_unix.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || hurd || (js && wasm) || linux || netbsd || openbsd || solaris
 // +build aix darwin dragonfly freebsd hurd js,wasm linux netbsd openbsd solaris
 
 package poll
@@ -230,7 +231,7 @@ func (fd *FD) ReadFrom(p []byte) (int, syscall.Sockaddr, error) {
 }
 
 // ReadMsg wraps the recvmsg network call.
-func (fd *FD) ReadMsg(p []byte, oob []byte) (int, int, int, syscall.Sockaddr, error) {
+func (fd *FD) ReadMsg(p []byte, oob []byte, flags int) (int, int, int, syscall.Sockaddr, error) {
 	if err := fd.readLock(); err != nil {
 		return 0, 0, 0, nil, err
 	}
@@ -239,7 +240,7 @@ func (fd *FD) ReadMsg(p []byte, oob []byte) (int, int, int, syscall.Sockaddr, er
 		return 0, 0, 0, nil, err
 	}
 	for {
-		n, oobn, flags, sa, err := syscall.Recvmsg(fd.Sysfd, p, oob, 0)
+		n, oobn, sysflags, sa, err := syscall.Recvmsg(fd.Sysfd, p, oob, flags)
 		if err != nil {
 			if err == syscall.EINTR {
 				continue
@@ -252,7 +253,7 @@ func (fd *FD) ReadMsg(p []byte, oob []byte) (int, int, int, syscall.Sockaddr, er
 			}
 		}
 		err = fd.eofError(n, err)
-		return n, oobn, flags, sa, err
+		return n, oobn, sysflags, sa, err
 	}
 }
 
diff --git a/libgo/go/internal/poll/fd_windows.go b/libgo/go/internal/poll/fd_windows.go
index d8c834f..4a51695 100644
--- a/libgo/go/internal/poll/fd_windows.go
+++ b/libgo/go/internal/poll/fd_windows.go
@@ -1013,7 +1013,7 @@ func sockaddrToRaw(sa syscall.Sockaddr) (unsafe.Pointer, int32, error) {
 }
 
 // ReadMsg wraps the WSARecvMsg network call.
-func (fd *FD) ReadMsg(p []byte, oob []byte) (int, int, int, syscall.Sockaddr, error) {
+func (fd *FD) ReadMsg(p []byte, oob []byte, flags int) (int, int, int, syscall.Sockaddr, error) {
 	if err := fd.readLock(); err != nil {
 		return 0, 0, 0, nil, err
 	}
@@ -1028,6 +1028,7 @@ func (fd *FD) ReadMsg(p []byte, oob []byte) (int, int, int, syscall.Sockaddr, er
 	o.rsa = new(syscall.RawSockaddrAny)
 	o.msg.Name = (syscall.Pointer)(unsafe.Pointer(o.rsa))
 	o.msg.Namelen = int32(unsafe.Sizeof(*o.rsa))
+	o.msg.Flags = uint32(flags)
 	n, err := execIO(o, func(o *operation) error {
 		return windows.WSARecvMsg(o.fd.Sysfd, &o.msg, &o.qty, &o.o, nil)
 	})
diff --git a/libgo/go/internal/poll/fd_writev_darwin.go b/libgo/go/internal/poll/fd_writev_darwin.go
index e202447..805fa2c 100644
--- a/libgo/go/internal/poll/fd_writev_darwin.go
+++ b/libgo/go/internal/poll/fd_writev_darwin.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build darwin
 // +build darwin
 
 package poll
diff --git a/libgo/go/internal/poll/fd_writev_illumos.go b/libgo/go/internal/poll/fd_writev_illumos.go
index 1fa47ab..a0b11ed 100644
--- a/libgo/go/internal/poll/fd_writev_illumos.go
+++ b/libgo/go/internal/poll/fd_writev_illumos.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build illumos
 // +build illumos
 
 package poll
diff --git a/libgo/go/internal/poll/fd_writev_unix.go b/libgo/go/internal/poll/fd_writev_unix.go
index daeec96..87f284a 100644
--- a/libgo/go/internal/poll/fd_writev_unix.go
+++ b/libgo/go/internal/poll/fd_writev_unix.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build dragonfly || freebsd || linux || netbsd || openbsd
 // +build dragonfly freebsd linux netbsd openbsd
 
 package poll
diff --git a/libgo/go/internal/poll/hook_cloexec.go b/libgo/go/internal/poll/hook_cloexec.go
index b8ce58d..18b445a 100644
--- a/libgo/go/internal/poll/hook_cloexec.go
+++ b/libgo/go/internal/poll/hook_cloexec.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build dragonfly || freebsd || hurd || illumos || linux || netbsd || openbsd
 // +build dragonfly freebsd hurd illumos linux netbsd openbsd
 
 package poll
diff --git a/libgo/go/internal/poll/hook_unix.go b/libgo/go/internal/poll/hook_unix.go
index 7bb6f88..5223fb7 100644
--- a/libgo/go/internal/poll/hook_unix.go
+++ b/libgo/go/internal/poll/hook_unix.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || hurd || (js && wasm) || linux || netbsd || openbsd || solaris
 // +build aix darwin dragonfly freebsd hurd js,wasm linux netbsd openbsd solaris
 
 package poll
diff --git a/libgo/go/internal/poll/iovec_illumos.go b/libgo/go/internal/poll/iovec_illumos.go
index 0570674..f4058b2 100644
--- a/libgo/go/internal/poll/iovec_illumos.go
+++ b/libgo/go/internal/poll/iovec_illumos.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build illumos
 // +build illumos
 
 package poll
diff --git a/libgo/go/internal/poll/iovec_unix.go b/libgo/go/internal/poll/iovec_unix.go
index 6f98947..6fd5d86 100644
--- a/libgo/go/internal/poll/iovec_unix.go
+++ b/libgo/go/internal/poll/iovec_unix.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd
 // +build darwin dragonfly freebsd linux netbsd openbsd
 
 package poll
diff --git a/libgo/go/internal/poll/sendfile_bsd.go b/libgo/go/internal/poll/sendfile_bsd.go
index 66005a9..3ba30a2 100644
--- a/libgo/go/internal/poll/sendfile_bsd.go
+++ b/libgo/go/internal/poll/sendfile_bsd.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build dragonfly || freebsd
 // +build dragonfly freebsd
 
 package poll
@@ -22,7 +23,7 @@ func SendFile(dstFD *FD, src int, pos, remain int64) (int64, error) {
 		return 0, err
 	}
 
-	dst := int(dstFD.Sysfd)
+	dst := dstFD.Sysfd
 	var written int64
 	var err error
 	for remain > 0 {
diff --git a/libgo/go/internal/poll/sendfile_solaris.go b/libgo/go/internal/poll/sendfile_solaris.go
index 748c851..0a88430 100644
--- a/libgo/go/internal/poll/sendfile_solaris.go
+++ b/libgo/go/internal/poll/sendfile_solaris.go
@@ -24,7 +24,7 @@ func SendFile(dstFD *FD, src int, pos, remain int64) (int64, error) {
 		return 0, err
 	}
 
-	dst := int(dstFD.Sysfd)
+	dst := dstFD.Sysfd
 	var written int64
 	var err error
 	for remain > 0 {
diff --git a/libgo/go/internal/poll/sock_cloexec.go b/libgo/go/internal/poll/sock_cloexec.go
index 09bc4b6..7daa11e 100644
--- a/libgo/go/internal/poll/sock_cloexec.go
+++ b/libgo/go/internal/poll/sock_cloexec.go
@@ -2,9 +2,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// This file implements sysSocket and accept for platforms that
-// provide a fast path for setting SetNonblock and CloseOnExec.
+// This file implements accept for platforms that provide a fast path for
+// setting SetNonblock and CloseOnExec.
 
+//go:build dragonfly || freebsd || hurd || illumos || linux || netbsd || openbsd
 // +build dragonfly freebsd hurd illumos linux netbsd openbsd
 
 package poll
diff --git a/libgo/go/internal/poll/sockopt.go b/libgo/go/internal/poll/sockopt.go
index 2c6b68b..975f84b 100644
--- a/libgo/go/internal/poll/sockopt.go
+++ b/libgo/go/internal/poll/sockopt.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || hurd || linux || netbsd || openbsd || solaris || windows
 // +build aix darwin dragonfly freebsd hurd linux netbsd openbsd solaris windows
 
 package poll
diff --git a/libgo/go/internal/poll/sockopt_unix.go b/libgo/go/internal/poll/sockopt_unix.go
index ef266d0..02a7859 100644
--- a/libgo/go/internal/poll/sockopt_unix.go
+++ b/libgo/go/internal/poll/sockopt_unix.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || hurd || linux || netbsd || openbsd || solaris
 // +build aix darwin dragonfly freebsd hurd linux netbsd openbsd solaris
 
 package poll
diff --git a/libgo/go/internal/poll/sockoptip.go b/libgo/go/internal/poll/sockoptip.go
index fc476bd..bcefa6b 100644
--- a/libgo/go/internal/poll/sockoptip.go
+++ b/libgo/go/internal/poll/sockoptip.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || dragonfly || freebsd || hurd || linux || netbsd || openbsd || solaris || windows
 // +build aix darwin dragonfly freebsd hurd linux netbsd openbsd solaris windows
 
 package poll
diff --git a/libgo/go/internal/poll/splice_linux.go b/libgo/go/internal/poll/splice_linux.go
index ca772e9..c7114f2 100644
--- a/libgo/go/internal/poll/splice_linux.go
+++ b/libgo/go/internal/poll/splice_linux.go
@@ -5,6 +5,8 @@
 package poll
 
 import (
+	"runtime"
+	"sync"
 	"sync/atomic"
 	"syscall"
 	"unsafe"
@@ -22,23 +24,23 @@ const (
 // Splice transfers at most remain bytes of data from src to dst, using the
 // splice system call to minimize copies of data from and to userspace.
 //
-// Splice creates a temporary pipe, to serve as a buffer for the data transfer.
+// Splice gets a pipe buffer from the pool or creates a new one if needed, to serve as a buffer for the data transfer.
 // src and dst must both be stream-oriented sockets.
 //
 // If err != nil, sc is the system call which caused the error.
 func Splice(dst, src *FD, remain int64) (written int64, handled bool, sc string, err error) {
-	prfd, pwfd, sc, err := newTempPipe()
+	p, sc, err := getPipe()
 	if err != nil {
 		return 0, false, sc, err
 	}
-	defer destroyTempPipe(prfd, pwfd)
+	defer putPipe(p)
 	var inPipe, n int
 	for err == nil && remain > 0 {
 		max := maxSpliceSize
 		if int64(max) > remain {
 			max = int(remain)
 		}
-		inPipe, err = spliceDrain(pwfd, src, max)
+		inPipe, err = spliceDrain(p.wfd, src, max)
 		// The operation is considered handled if splice returns no
 		// error, or an error other than EINVAL. An EINVAL means the
 		// kernel does not support splice for the socket type of src.
@@ -51,13 +53,16 @@ func Splice(dst, src *FD, remain int64) (written int64, handled bool, sc string,
 		// If inPipe == 0 && err == nil, src is at EOF, and the
 		// transfer is complete.
 		handled = handled || (err != syscall.EINVAL)
-		if err != nil || (inPipe == 0 && err == nil) {
+		if err != nil || inPipe == 0 {
 			break
 		}
-		n, err = splicePump(dst, prfd, inPipe)
+		p.data += inPipe
+
+		n, err = splicePump(dst, p.rfd, inPipe)
 		if n > 0 {
 			written += int64(n)
 			remain -= int64(n)
+			p.data -= n
 		}
 	}
 	if err != nil {
@@ -148,13 +153,58 @@ func splice(out int, in int, max int, flags int) (int, error) {
 	return int(n), err
 }
 
+type splicePipe struct {
+	rfd  int
+	wfd  int
+	data int
+}
+
+// splicePipePool caches pipes to avoid high-frequency construction and destruction of pipe buffers.
+// The garbage collector will free all pipes in the sync.Pool periodically, thus we need to set up
+// a finalizer for each pipe to close its file descriptors before the actual GC.
+var splicePipePool = sync.Pool{New: newPoolPipe}
+
+func newPoolPipe() interface{} {
+	// Discard the error which occurred during the creation of pipe buffer,
+	// redirecting the data transmission to the conventional way utilizing read() + write() as a fallback.
+	p := newPipe()
+	if p == nil {
+		return nil
+	}
+	runtime.SetFinalizer(p, destroyPipe)
+	return p
+}
+
+// getPipe tries to acquire a pipe buffer from the pool or create a new one with newPipe() if it gets nil from the cache.
+//
+// Note that it may fail to create a new pipe buffer by newPipe(), in which case getPipe() will return a generic error
+// and system call name splice in a string as the indication.
+func getPipe() (*splicePipe, string, error) {
+	v := splicePipePool.Get()
+	if v == nil {
+		return nil, "splice", syscall.EINVAL
+	}
+	return v.(*splicePipe), "", nil
+}
+
+func putPipe(p *splicePipe) {
+	// If there is still data left in the pipe,
+	// then close and discard it instead of putting it back into the pool.
+	if p.data != 0 {
+		runtime.SetFinalizer(p, nil)
+		destroyPipe(p)
+		return
+	}
+	splicePipePool.Put(p)
+}
+
 var disableSplice unsafe.Pointer
 
-// newTempPipe sets up a temporary pipe for a splice operation.
-func newTempPipe() (prfd, pwfd int, sc string, err error) {
+// newPipe sets up a pipe for a splice operation.
+func newPipe() (sp *splicePipe) {
 	p := (*bool)(atomic.LoadPointer(&disableSplice))
 	if p != nil && *p {
-		return -1, -1, "splice", syscall.EINVAL
+		return nil
 	}
 
 	var fds [2]int
@@ -164,9 +214,11 @@ func newTempPipe() (prfd, pwfd int, sc string, err error) {
 	// closed.
 	const flags = syscall.O_CLOEXEC | syscall.O_NONBLOCK
 	if err := syscall.Pipe2(fds[:], flags); err != nil {
-		return -1, -1, "pipe2", err
+		return nil
 	}
 
+	sp = &splicePipe{rfd: fds[0], wfd: fds[1]}
+
 	if p == nil {
 		p = new(bool)
 		defer atomic.StorePointer(&disableSplice, unsafe.Pointer(p))
@@ -174,25 +226,21 @@ func newTempPipe() (prfd, pwfd int, sc string, err error) {
 		// F_GETPIPE_SZ was added in 2.6.35, which does not have the -EAGAIN bug.
 		if syscall.F_GETPIPE_SZ == 0 {
 			*p = true
-			destroyTempPipe(fds[0], fds[1])
-			return -1, -1, "fcntl", syscall.EINVAL
+			destroyPipe(sp)
+			return nil
 		}
 		if _, err := fcntl(fds[0], syscall.F_GETPIPE_SZ, 0); err != nil {
 			*p = true
-			destroyTempPipe(fds[0], fds[1])
-			return -1, -1, "fcntl", err
+			destroyPipe(sp)
+			return nil
 		}
 	}
 
-	return fds[0], fds[1], "", nil
+	return
 }
 
-// destroyTempPipe destroys a temporary pipe.
-func destroyTempPipe(prfd, pwfd int) error {
-	err := CloseFunc(prfd)
-	err1 := CloseFunc(pwfd)
-	if err == nil {
-		return err1
-	}
-	return err
+// destroyPipe destroys a pipe.
+func destroyPipe(p *splicePipe) {
+	CloseFunc(p.rfd)
+	CloseFunc(p.wfd)
 }
diff --git a/libgo/go/internal/poll/splice_linux_test.go b/libgo/go/internal/poll/splice_linux_test.go
new file mode 100644
index 0000000..206a027
--- /dev/null
+++ b/libgo/go/internal/poll/splice_linux_test.go
@@ -0,0 +1,122 @@
+// Copyright 2021 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 poll_test
+
+import (
+	"internal/poll"
+	"runtime"
+	"syscall"
+	"testing"
+	"time"
+)
+
+// checkPipes returns true if all pipes are closed properly, false otherwise.
+func checkPipes(fds []int) bool {
+	for _, fd := range fds {
+		// Check if each pipe fd has been closed.
+		_, err := poll.Fcntl(fd, syscall.F_GETPIPE_SZ, 0)
+		if err == nil {
+			return false
+		}
+	}
+	return true
+}
+
+func TestSplicePipePool(t *testing.T) {
+	if runtime.Compiler == "gccgo" {
+		t.Skip("gofrontend conservative stack collection causes this test to fail")
+	}
+
+	const N = 64
+	var (
+		p   *poll.SplicePipe
+		ps  []*poll.SplicePipe
+		fds []int
+		err error
+	)
+	for i := 0; i < N; i++ {
+		p, _, err = poll.GetPipe()
+		if err != nil {
+			t.Skip("failed to create pipe, skip this test")
+		}
+		_, pwfd := poll.GetPipeFds(p)
+		fds = append(fds, pwfd)
+		ps = append(ps, p)
+	}
+	for _, p = range ps {
+		poll.PutPipe(p)
+	}
+	ps = nil
+	p = nil
+
+	// Exploit the timeout of "go test" as a timer for the subsequent verification.
+	timeout := 5 * time.Minute
+	if deadline, ok := t.Deadline(); ok {
+		timeout = deadline.Sub(time.Now())
+		timeout -= timeout / 10 // Leave 10% headroom for cleanup.
+	}
+	expiredTime := time.NewTimer(timeout)
+	defer expiredTime.Stop()
+
+	// Trigger garbage collection repeatedly, waiting for all pipes in sync.Pool
+	// to either be deallocated and closed, or to time out.
+	for {
+		runtime.GC()
+		time.Sleep(10 * time.Millisecond)
+		if checkPipes(fds) {
+			break
+		}
+		select {
+		case <-expiredTime.C:
+			t.Fatal("at least one pipe is still open")
+		default:
+		}
+	}
+}
+
+func BenchmarkSplicePipe(b *testing.B) {
+	b.Run("SplicePipeWithPool", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			p, _, err := poll.GetPipe()
+			if err != nil {
+				continue
+			}
+			poll.PutPipe(p)
+		}
+	})
+	b.Run("SplicePipeWithoutPool", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			p := poll.NewPipe()
+			if p == nil {
+				b.Skip("newPipe returned nil")
+			}
+			poll.DestroyPipe(p)
+		}
+	})
+}
+
+func BenchmarkSplicePipePoolParallel(b *testing.B) {
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			p, _, err := poll.GetPipe()
+			if err != nil {
+				continue
+			}
+			poll.PutPipe(p)
+		}
+	})
+}
+
+func BenchmarkSplicePipeNativeParallel(b *testing.B) {
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			p := poll.NewPipe()
+			if p == nil {
+				b.Skip("newPipe returned nil")
+			}
+			poll.DestroyPipe(p)
+		}
+	})
+}
diff --git a/libgo/go/internal/poll/strconv.go b/libgo/go/internal/poll/strconv.go
index 21cb40d..c98332d 100644
--- a/libgo/go/internal/poll/strconv.go
+++ b/libgo/go/internal/poll/strconv.go
@@ -2,38 +2,11 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build plan9
 // +build plan9
 
-// Simple conversions to avoid depending on strconv.
-
 package poll
 
-// Convert integer to decimal string
-func itoa(val int) string {
-	if val < 0 {
-		return "-" + uitoa(uint(-val))
-	}
-	return uitoa(uint(val))
-}
-
-// Convert unsigned integer to decimal string
-func uitoa(val uint) string {
-	if val == 0 { // avoid string allocation
-		return "0"
-	}
-	var buf [20]byte // big enough for 64bit value base 10
-	i := len(buf) - 1
-	for val >= 10 {
-		q := val / 10
-		buf[i] = byte('0' + val - q*10)
-		i--
-		val = q
-	}
-	// val < 10
-	buf[i] = byte('0' + val)
-	return string(buf[i:])
-}
-
 // stringsHasSuffix is strings.HasSuffix. It reports whether s ends in
 // suffix.
 func stringsHasSuffix(s, suffix string) bool {
diff --git a/libgo/go/internal/poll/sys_cloexec.go b/libgo/go/internal/poll/sys_cloexec.go
index 4b3c642..7e6d422 100644
--- a/libgo/go/internal/poll/sys_cloexec.go
+++ b/libgo/go/internal/poll/sys_cloexec.go
@@ -2,9 +2,10 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// This file implements sysSocket and accept for platforms that do not
-// provide a fast path for setting SetNonblock and CloseOnExec.
+// This file implements accept for platforms that do not provide a fast path for
+// setting SetNonblock and CloseOnExec.
 
+//go:build aix || darwin || (js && wasm) || (solaris && !illumos)
 // +build aix darwin js,wasm solaris,!illumos
 
 package poll
diff --git a/libgo/go/internal/poll/writev.go b/libgo/go/internal/poll/writev.go
index 0123fc3..824de75 100644
--- a/libgo/go/internal/poll/writev.go
+++ b/libgo/go/internal/poll/writev.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build darwin || dragonfly || freebsd || illumos || linux || netbsd || openbsd
 // +build darwin dragonfly freebsd illumos linux netbsd openbsd
 
 package poll
diff --git a/libgo/go/internal/race/norace.go b/libgo/go/internal/race/norace.go
index d83c016..67b1305 100644
--- a/libgo/go/internal/race/norace.go
+++ b/libgo/go/internal/race/norace.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !race
 // +build !race
 
 package race
diff --git a/libgo/go/internal/race/race.go b/libgo/go/internal/race/race.go
index 2e7d97b..40f2c99 100644
--- a/libgo/go/internal/race/race.go
+++ b/libgo/go/internal/race/race.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build race
 // +build race
 
 package race
diff --git a/libgo/go/internal/reflectlite/all_test.go b/libgo/go/internal/reflectlite/all_test.go
index 2ea28e0..e15f364 100644
--- a/libgo/go/internal/reflectlite/all_test.go
+++ b/libgo/go/internal/reflectlite/all_test.go
@@ -982,21 +982,6 @@ func TestNames(t *testing.T) {
 	}
 }
 
-type embed struct {
-	EmbedWithUnexpMeth
-}
-
-/*
-func TestNameBytesAreAligned(t *testing.T) {
-	typ := TypeOf(embed{})
-	b := FirstMethodNameBytes(typ)
-	v := uintptr(unsafe.Pointer(b))
-	if v%unsafe.Alignof((*byte)(nil)) != 0 {
-		t.Errorf("reflect.name.bytes pointer is not aligned: %x", v)
-	}
-}
-*/
-
 // TestUnaddressableField tests that the reflect package will not allow
 // a type from another package to be used as a named type with an
 // unexported field.
diff --git a/libgo/go/internal/reflectlite/type.go b/libgo/go/internal/reflectlite/type.go
index 0c1b994..db1469d 100644
--- a/libgo/go/internal/reflectlite/type.go
+++ b/libgo/go/internal/reflectlite/type.go
@@ -67,7 +67,7 @@ type Type interface {
 }
 
 /*
- * These data structures are known to the compiler (../../cmd/internal/gc/reflect.go).
+ * These data structures are known to the compiler (../../cmd/internal/reflectdata/reflect.go).
  * A few are known to ../runtime/type.go to convey to debuggers.
  * They are also known to ../runtime/type.go.
  */
diff --git a/libgo/go/internal/syscall/execenv/execenv_default.go b/libgo/go/internal/syscall/execenv/execenv_default.go
index 4bdbb55..73289f1 100644
--- a/libgo/go/internal/syscall/execenv/execenv_default.go
+++ b/libgo/go/internal/syscall/execenv/execenv_default.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !windows
 // +build !windows
 
 package execenv
diff --git a/libgo/go/internal/syscall/execenv/execenv_windows.go b/libgo/go/internal/syscall/execenv/execenv_windows.go
index b50029c..6c06549 100644
--- a/libgo/go/internal/syscall/execenv/execenv_windows.go
+++ b/libgo/go/internal/syscall/execenv/execenv_windows.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build windows
 // +build windows
 
 package execenv
diff --git a/libgo/go/internal/syscall/unix/at.go b/libgo/go/internal/syscall/unix/at.go
index a602d3a..5059af3 100644
--- a/libgo/go/internal/syscall/unix/at.go
+++ b/libgo/go/internal/syscall/unix/at.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//-go:build linux || openbsd || netbsd || dragonfly
 // -build linux openbsd netbsd dragonfly
 
 package unix
diff --git a/libgo/go/internal/syscall/unix/getentropy_darwin.go b/libgo/go/internal/syscall/unix/getentropy_darwin.go
new file mode 100644
index 0000000..e1a410a
--- /dev/null
+++ b/libgo/go/internal/syscall/unix/getentropy_darwin.go
@@ -0,0 +1,30 @@
+// Copyright 2021 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 unix
+
+import (
+	"internal/abi"
+	"syscall"
+	"unsafe"
+)
+
+//go:cgo_import_dynamic libc_getentropy getentropy "/usr/lib/libSystem.B.dylib"
+
+func libc_getentropy_trampoline()
+
+// GetEntropy calls the macOS getentropy system call.
+func GetEntropy(p []byte) error {
+	_, _, errno := syscall_syscall(abi.FuncPCABI0(libc_getentropy_trampoline),
+		uintptr(unsafe.Pointer(&p[0])),
+		uintptr(len(p)),
+		0)
+	if errno != 0 {
+		return errno
+	}
+	return nil
+}
+
+//go:linkname syscall_syscall syscall.syscall
+func syscall_syscall(fn, a1, a2, a3 uintptr) (r1, r2 uintptr, err syscall.Errno)
diff --git a/libgo/go/internal/syscall/unix/getrandom.go b/libgo/go/internal/syscall/unix/getrandom.go
new file mode 100644
index 0000000..d2c58c0
--- /dev/null
+++ b/libgo/go/internal/syscall/unix/getrandom.go
@@ -0,0 +1,40 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build dragonfly || freebsd || linux
+// +build dragonfly freebsd linux
+
+package unix
+
+import (
+	"sync/atomic"
+	"syscall"
+	"unsafe"
+)
+
+var getrandomUnsupported int32 // atomic
+
+// GetRandomFlag is a flag supported by the getrandom system call.
+type GetRandomFlag uintptr
+
+// GetRandom calls the getrandom system call.
+func GetRandom(p []byte, flags GetRandomFlag) (n int, err error) {
+	if len(p) == 0 {
+		return 0, nil
+	}
+	if atomic.LoadInt32(&getrandomUnsupported) != 0 {
+		return 0, syscall.ENOSYS
+	}
+	r1, _, errno := syscall.Syscall(getrandomTrap,
+		uintptr(unsafe.Pointer(&p[0])),
+		uintptr(len(p)),
+		uintptr(flags))
+	if errno != 0 {
+		if errno == syscall.ENOSYS {
+			atomic.StoreInt32(&getrandomUnsupported, 1)
+		}
+		return 0, errno
+	}
+	return int(r1), nil
+}
diff --git a/libgo/go/internal/syscall/unix/getrandom_dragonfly.go b/libgo/go/internal/syscall/unix/getrandom_dragonfly.go
new file mode 100644
index 0000000..fbf78f9
--- /dev/null
+++ b/libgo/go/internal/syscall/unix/getrandom_dragonfly.go
@@ -0,0 +1,16 @@
+// Copyright 2021 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 unix
+
+// DragonFlyBSD getrandom system call number.
+const getrandomTrap uintptr = 550
+
+const (
+	// GRND_RANDOM is only set for portability purpose, no-op on DragonFlyBSD.
+	GRND_RANDOM GetRandomFlag = 0x0001
+
+	// GRND_NONBLOCK means return EAGAIN rather than blocking.
+	GRND_NONBLOCK GetRandomFlag = 0x0002
+)
diff --git a/libgo/go/internal/syscall/unix/getrandom_freebsd.go b/libgo/go/internal/syscall/unix/getrandom_freebsd.go
index f1ba573..8c4f3df 100644
--- a/libgo/go/internal/syscall/unix/getrandom_freebsd.go
+++ b/libgo/go/internal/syscall/unix/getrandom_freebsd.go
@@ -4,19 +4,8 @@
 
 package unix
 
-import (
-	"sync/atomic"
-	"syscall"
-	"unsafe"
-)
-
-var randomUnsupported int32 // atomic
-
 // FreeBSD getrandom system call number.
-const randomTrap uintptr = 563
-
-// GetRandomFlag is a flag supported by the getrandom system call.
-type GetRandomFlag uintptr
+const getrandomTrap uintptr = 563
 
 const (
 	// GRND_NONBLOCK means return EAGAIN rather than blocking.
@@ -25,24 +14,3 @@ const (
 	// GRND_RANDOM is only set for portability purpose, no-op on FreeBSD.
 	GRND_RANDOM GetRandomFlag = 0x0002
 )
-
-// GetRandom calls the FreeBSD getrandom system call.
-func GetRandom(p []byte, flags GetRandomFlag) (n int, err error) {
-	if len(p) == 0 {
-		return 0, nil
-	}
-	if atomic.LoadInt32(&randomUnsupported) != 0 {
-		return 0, syscall.ENOSYS
-	}
-	r1, _, errno := syscall.Syscall(randomTrap,
-		uintptr(unsafe.Pointer(&p[0])),
-		uintptr(len(p)),
-		uintptr(flags))
-	if errno != 0 {
-		if errno == syscall.ENOSYS {
-			atomic.StoreInt32(&randomUnsupported, 1)
-		}
-		return 0, errno
-	}
-	return int(r1), nil
-}
diff --git a/libgo/go/internal/syscall/unix/getrandom_linux.go b/libgo/go/internal/syscall/unix/getrandom_linux.go
index 490d516..8ccd8d3 100644
--- a/libgo/go/internal/syscall/unix/getrandom_linux.go
+++ b/libgo/go/internal/syscall/unix/getrandom_linux.go
@@ -4,17 +4,6 @@
 
 package unix
 
-import (
-	"sync/atomic"
-	"syscall"
-	"unsafe"
-)
-
-var randomUnsupported int32 // atomic
-
-// GetRandomFlag is a flag supported by the getrandom system call.
-type GetRandomFlag uintptr
-
 const (
 	// GRND_NONBLOCK means return EAGAIN rather than blocking.
 	GRND_NONBLOCK GetRandomFlag = 0x0001
@@ -22,25 +11,3 @@ const (
 	// GRND_RANDOM means use the /dev/random pool instead of /dev/urandom.
 	GRND_RANDOM GetRandomFlag = 0x0002
 )
-
-// GetRandom calls the Linux getrandom system call.
-// See https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c6e9d6f38894798696f23c8084ca7edbf16ee895
-func GetRandom(p []byte, flags GetRandomFlag) (n int, err error) {
-	if len(p) == 0 {
-		return 0, nil
-	}
-	if atomic.LoadInt32(&randomUnsupported) != 0 {
-		return 0, syscall.ENOSYS
-	}
-	r1, _, errno := syscall.Syscall(getrandomTrap,
-		uintptr(unsafe.Pointer(&p[0])),
-		uintptr(len(p)),
-		uintptr(flags))
-	if errno != 0 {
-		if errno == syscall.ENOSYS {
-			atomic.StoreInt32(&randomUnsupported, 1)
-		}
-		return 0, errno
-	}
-	return int(r1), nil
-}
diff --git a/libgo/go/internal/syscall/unix/getrandom_solaris.go b/libgo/go/internal/syscall/unix/getrandom_solaris.go
new file mode 100644
index 0000000..caf9b60
--- /dev/null
+++ b/libgo/go/internal/syscall/unix/getrandom_solaris.go
@@ -0,0 +1,46 @@
+// Copyright 2021 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 unix
+
+import (
+	"sync/atomic"
+	"syscall"
+	"unsafe"
+)
+
+//extern getrandom
+func libc_getrandom(*byte, uintptr, uint32) uintptr
+
+// GetRandomFlag is a flag supported by the getrandom system call.
+type GetRandomFlag uintptr
+
+const (
+	// GRND_NONBLOCK means return EAGAIN rather than blocking.
+	GRND_NONBLOCK GetRandomFlag = 0x0001
+
+	// GRND_RANDOM means use the /dev/random pool instead of /dev/urandom.
+	GRND_RANDOM GetRandomFlag = 0x0002
+)
+
+// GetRandom calls the getrandom system call.
+func GetRandom(p []byte, flags GetRandomFlag) (n int, err error) {
+	if len(p) == 0 {
+		return 0, nil
+	}
+	if atomic.LoadInt32(&getrandomUnsupported) != 0 {
+		return 0, syscall.ENOSYS
+	}
+	syscall.Entersyscall()
+	r1 := libc_getrandom(&p[0], uintptr(len(p)), uint32(flags))
+	syscall.Exitsyscall()
+	if r1 == 0 {
+		errno := syscall.GetErrno()
+		if errno == syscall.ENOSYS {
+			atomic.StoreInt32(&getrandomUnsupported, 1)
+		}
+		return 0, errno
+	}
+	return int(r1), nil
+}
diff --git a/libgo/go/internal/syscall/unix/nonblocking.go b/libgo/go/internal/syscall/unix/nonblocking.go
index 1734cdc..dc2e107 100644
--- a/libgo/go/internal/syscall/unix/nonblocking.go
+++ b/libgo/go/internal/syscall/unix/nonblocking.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build dragonfly || freebsd || hurd || linux || netbsd || openbsd
 // +build dragonfly freebsd hurd linux netbsd openbsd
 
 package unix
diff --git a/libgo/go/internal/syscall/unix/nonblocking_js.go b/libgo/go/internal/syscall/unix/nonblocking_js.go
index a360b53..a5a5080 100644
--- a/libgo/go/internal/syscall/unix/nonblocking_js.go
+++ b/libgo/go/internal/syscall/unix/nonblocking_js.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build js && wasm
 // +build js,wasm
 
 package unix
diff --git a/libgo/go/internal/syscall/unix/nonblocking_libc.go b/libgo/go/internal/syscall/unix/nonblocking_libc.go
index 464314d..876fb16 100644
--- a/libgo/go/internal/syscall/unix/nonblocking_libc.go
+++ b/libgo/go/internal/syscall/unix/nonblocking_libc.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build aix || darwin || solaris
 // +build aix darwin solaris
 
 package unix
diff --git a/libgo/go/internal/syscall/unix/sysnum_linux_generic.go b/libgo/go/internal/syscall/unix/sysnum_linux_generic.go
index 3d34fdb..d8db1bb 100644
--- a/libgo/go/internal/syscall/unix/sysnum_linux_generic.go
+++ b/libgo/go/internal/syscall/unix/sysnum_linux_generic.go
@@ -2,8 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build linux && (arm64 || riscv64 || arm64be || nios2 || riscv)
 // +build linux
-// +build arm64 arm64be nios2 riscv riscv64
+// +build arm64 riscv64 arm64be nios2 riscv
 
 package unix
 
diff --git a/libgo/go/internal/syscall/unix/sysnum_linux_mips64x.go b/libgo/go/internal/syscall/unix/sysnum_linux_mips64x.go
index 6680942..f353d4d 100644
--- a/libgo/go/internal/syscall/unix/sysnum_linux_mips64x.go
+++ b/libgo/go/internal/syscall/unix/sysnum_linux_mips64x.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips64 || mips64le
 // +build mips64 mips64le
 
 package unix
diff --git a/libgo/go/internal/syscall/unix/sysnum_linux_mipsx.go b/libgo/go/internal/syscall/unix/sysnum_linux_mipsx.go
index 185d832..4ed4715 100644
--- a/libgo/go/internal/syscall/unix/sysnum_linux_mipsx.go
+++ b/libgo/go/internal/syscall/unix/sysnum_linux_mipsx.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build mips || mipsle
 // +build mips mipsle
 
 package unix
diff --git a/libgo/go/internal/syscall/unix/sysnum_linux_ppc64x.go b/libgo/go/internal/syscall/unix/sysnum_linux_ppc64x.go
index aa2e81a..5befa08 100644
--- a/libgo/go/internal/syscall/unix/sysnum_linux_ppc64x.go
+++ b/libgo/go/internal/syscall/unix/sysnum_linux_ppc64x.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build ppc || ppc64 || ppc64le
 // +build ppc ppc64 ppc64le
 
 package unix
diff --git a/libgo/go/internal/testenv/testenv_cgo.go b/libgo/go/internal/testenv/testenv_cgo.go
index e3d4d16..02f08f5 100644
--- a/libgo/go/internal/testenv/testenv_cgo.go
+++ b/libgo/go/internal/testenv/testenv_cgo.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build cgo
 // +build cgo
 
 package testenv
diff --git a/libgo/go/internal/testenv/testenv_notwin.go b/libgo/go/internal/testenv/testenv_notwin.go
index ccb5d55..846ec93 100644
--- a/libgo/go/internal/testenv/testenv_notwin.go
+++ b/libgo/go/internal/testenv/testenv_notwin.go
@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+//go:build !windows
 // +build !windows
 
 package testenv
diff --git a/libgo/go/internal/trace/parser.go b/libgo/go/internal/trace/parser.go
index c371ff3..254f201 100644
--- a/libgo/go/internal/trace/parser.go
+++ b/libgo/go/internal/trace/parser.go
@@ -1042,8 +1042,8 @@ const (
 	EvGoSysBlock        = 30 // syscall blocks [timestamp]
 	EvGoWaiting         = 31 // denotes that goroutine is blocked when tracing starts [timestamp, goroutine id]
 	EvGoInSyscall       = 32 // denotes that goroutine is in syscall when tracing starts [timestamp, goroutine id]
-	EvHeapAlloc         = 33 // memstats.heap_live change [timestamp, heap_alloc]
-	EvNextGC            = 34 // memstats.next_gc change [timestamp, next_gc]
+	EvHeapAlloc         = 33 // gcController.heapLive change [timestamp, heap live bytes]
+	EvHeapGoal          = 34 // gcController.heapGoal change [timestamp, heap goal bytes]
 	EvTimerGoroutine    = 35 // denotes timer goroutine [timer goroutine id]
 	EvFutileWakeup      = 36 // denotes that the previous wakeup of this goroutine was futile [timestamp]
 	EvString            = 37 // string dictionary entry [ID, length, string]
@@ -1102,7 +1102,7 @@ var EventDescriptions = [EvCount]struct {
 	EvGoWaiting:         {"GoWaiting", 1005, false, []string{"g"}, nil},
 	EvGoInSyscall:       {"GoInSyscall", 1005, false, []string{"g"}, nil},
 	EvHeapAlloc:         {"HeapAlloc", 1005, false, []string{"mem"}, nil},
-	EvNextGC:            {"NextGC", 1005, false, []string{"mem"}, nil},
+	EvHeapGoal:          {"HeapGoal", 1005, false, []string{"mem"}, nil},
 	EvTimerGoroutine:    {"TimerGoroutine", 1005, false, []string{"g"}, nil}, // in 1.5 format it was {"g", "unused"}
 	EvFutileWakeup:      {"FutileWakeup", 1005, false, []string{}, nil},
 	EvString:            {"String", 1007, false, []string{}, nil},