gcWriteBarrier and wbBufFlush assume that not writing to an argument
variable is sufficient to not clobber the corresponding argument slot.
This assumption lets us simplify the write barrier assembly code,
speed up the flush path, and reduce the stack usage of the write
barrier.

But it is an assumption, so this CL documents it to make this clear.

Alternatively, we could separate the register spill slots from the
argument slots in the write barrier, but that loses the advantages
above. On the other hand, it's extremely unlikely that we'll change
the behavior of the compiler to start clobbering argument slots (if
anything, we'd probably change it to *not* clobber argument slots even
if you wrote to the arguments).

Fixes #25512.

Change-Id: Ib2cf29c0d90956ca02b997ef6e7fa56fc8044efe
Reviewed-on: https://go-review.googlesource.com/127815
Reviewed-by: Cherry Zhang <cherryyz@google.com>

VERSION

@@ -0,0 +1 @@
go1.11rc1

doc/contribute.html

@@ -292,6 +292,25 @@ <h3>Check the issue tracker</h3>
	</li>
</ul>

<p>
You can use GitHub's search functionality to find issues to help out with. Examples:
</p>

<ul>
	<li>
	Issues that need investigation: <a href="https://github.com/golang/go/issues?q=is%3Aissue+is%3Aopen+label%3ANeedsInvestigation"><code>is:issue is:open label:NeedsInvestigation</code></a>
	</li>
	<li>
	Issues that need a fix: <a href="https://github.com/golang/go/issues?q=is%3Aissue+is%3Aopen+label%3ANeedsFix"><code>is:issue is:open label:NeedsFix</code></a>
	</li>
	<li>
	Issues that need a fix and have a CL: <a href="https://github.com/golang/go/issues?q=is%3Aissue+is%3Aopen+label%3ANeedsFix+%22golang.org%2Fcl%22"><code>is:issue is:open label:NeedsFix "golang.org/cl"</code></a>
	</li>
	<li>
	Issues that need a fix and do not have a CL: <a href="https://github.com/golang/go/issues?q=is%3Aissue+is%3Aopen+label%3ANeedsFix+NOT+%22golang.org%2Fcl%22"><code>is:issue is:open label:NeedsFix NOT "golang.org/cl"</code></a>
	</li>
</ul>

<h3 id="design">Open an issue for any new problem</h3>

<p>

doc/go1.11.html

@@ -299,6 +299,22 @@ <h3 id="vet">Vet</h3>
  a warning to be printed, and <code>vet</code> to exit with status 1.
</p>

<p><!-- CL 108559 -->
  Additionally, <a href="/cmd/vet"><code>go</code>&nbsp;<code>vet</code></a>
  has become more robust when format-checking <code>printf</code> wrappers.
  Vet now detects the mistake in this example:
</p>

<pre>
func wrapper(s string, args ...interface{}) {
	fmt.Printf(s, args...)
}

func main() {
	wrapper("%s", 42)
}
</pre>

<h3 id="trace">Trace</h3>

<p><!-- CL 63274 -->
@@ -311,6 +327,19 @@ <h3 id="trace">Trace</h3>
  user task/region analysis page.
</p>

<h3 id="cgo">Cgo</h3>

<p>
Since Go 1.10, cgo has translated some C pointer types to the Go
type <code>uintptr</code>. These types include
the <code>CFTypeRef</code> hierarchy in Darwin's CoreFoundation
framework and the <code>jobject</code> hierarchy in Java's JNI
interface. In Go 1.11, several improvements have been made to the code
that detects these types. Code that uses these types may need some
updating. See the <a href="go1.10.html#cgo">Go 1.10 release notes</a> for
details. <!-- CL 126275, CL 127156, CL 122217, CL 122575, CL 123177 -->
</p>

<h3 id="godoc">Godoc</h3>

<p>

doc/security.html

@@ -38,7 +38,7 @@ <h3>Reporting a Security Bug</h3>
</p>

<ul>
<li>Primary security coordinator: <a href="mailto:adg@golang.org">Andrew Gerrand</a>  (<a href="https://drive.google.com/a/google.com/file/d/0B42ZAZN5yFufRldybEVNandRN2c/view">public key</a>).</li>
<li>Primary security coordinator: <a href="mailto:filippo@golang.org">Filippo Valsorda</a> (<a href="https://keybase.io/filippo/pgp_keys.asc">public key</a>).</li>
<li>Secondary coordinator: <a href="mailto:agl@golang.org">Adam Langley</a> (<a href="https://www.imperialviolet.org/key.asc">public key</a>).</li>
<li>If you receive no response, mail <a href="mailto:golang-dev@googlegroups.com">golang-dev@googlegroups.com</a> or use the <a href="https://groups.google.com/forum/#!forum/golang-dev">golang-dev web interface</a>.</li>
</ul>

src/cmd/asm/internal/arch/arch.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.

// Package arch defines architecture-specific information and support functions.
package arch

import (

src/cmd/compile/internal/ssa/testdata/hist.dlv-opt.nexts

@@ -2,150 +2,83 @@
55:	func test() {
57:		l := line{point{1 + zero, 2 + zero}, point{3 + zero, 4 + zero}}
58:		tinycall()                // this forces l etc to stack
57:		l := line{point{1 + zero, 2 + zero}, point{3 + zero, 4 + zero}}
59:		dx := l.end.x - l.begin.x //gdb-dbg=(l.begin.x,l.end.y)//gdb-opt=(l,dx/O,dy/O)
60:		dy := l.end.y - l.begin.y //gdb-opt=(dx,dy/O)
61:		sink = dx + dy            //gdb-opt=(dx,dy)
63:		hist := make([]int, 7)                                //gdb-opt=(dx/O,dy/O) // TODO sink is missing if this code is in 'test' instead of 'main'
64:		var reader io.Reader = strings.NewReader(cannedInput) //gdb-dbg=(hist/A) // TODO cannedInput/A is missing if this code is in 'test' instead of 'main'
65:		if len(os.Args) > 1 {
73:		scanner := bufio.NewScanner(reader)
63:		hist := make([]int, 7)                                //gdb-opt=(dx/O,dy/O) // TODO sink is missing if this code is in 'test' instead of 'main'
74:		for scanner.Scan() { //gdb-opt=(scanner/A)
81:			hist = ensure(int(i), hist)
74:		for scanner.Scan() { //gdb-opt=(scanner/A)
76:			i, err := strconv.ParseInt(s, 10, 64)
77:			if err != nil { //gdb-dbg=(i) //gdb-opt=(err,hist,i)
76:			i, err := strconv.ParseInt(s, 10, 64)
81:			hist = ensure(int(i), hist)
82:			hist[int(i)]++
81:			hist = ensure(int(i), hist)
74:		for scanner.Scan() { //gdb-opt=(scanner/A)
76:			i, err := strconv.ParseInt(s, 10, 64)
77:			if err != nil { //gdb-dbg=(i) //gdb-opt=(err,hist,i)
76:			i, err := strconv.ParseInt(s, 10, 64)
81:			hist = ensure(int(i), hist)
82:			hist[int(i)]++
81:			hist = ensure(int(i), hist)
74:		for scanner.Scan() { //gdb-opt=(scanner/A)
76:			i, err := strconv.ParseInt(s, 10, 64)
77:			if err != nil { //gdb-dbg=(i) //gdb-opt=(err,hist,i)
76:			i, err := strconv.ParseInt(s, 10, 64)
81:			hist = ensure(int(i), hist)
82:			hist[int(i)]++
81:			hist = ensure(int(i), hist)
74:		for scanner.Scan() { //gdb-opt=(scanner/A)
76:			i, err := strconv.ParseInt(s, 10, 64)
77:			if err != nil { //gdb-dbg=(i) //gdb-opt=(err,hist,i)
76:			i, err := strconv.ParseInt(s, 10, 64)
81:			hist = ensure(int(i), hist)
82:			hist[int(i)]++
81:			hist = ensure(int(i), hist)
74:		for scanner.Scan() { //gdb-opt=(scanner/A)
76:			i, err := strconv.ParseInt(s, 10, 64)
77:			if err != nil { //gdb-dbg=(i) //gdb-opt=(err,hist,i)
76:			i, err := strconv.ParseInt(s, 10, 64)
81:			hist = ensure(int(i), hist)
82:			hist[int(i)]++
81:			hist = ensure(int(i), hist)
74:		for scanner.Scan() { //gdb-opt=(scanner/A)
76:			i, err := strconv.ParseInt(s, 10, 64)
77:			if err != nil { //gdb-dbg=(i) //gdb-opt=(err,hist,i)
76:			i, err := strconv.ParseInt(s, 10, 64)
81:			hist = ensure(int(i), hist)
82:			hist[int(i)]++
81:			hist = ensure(int(i), hist)
74:		for scanner.Scan() { //gdb-opt=(scanner/A)
76:			i, err := strconv.ParseInt(s, 10, 64)
77:			if err != nil { //gdb-dbg=(i) //gdb-opt=(err,hist,i)
76:			i, err := strconv.ParseInt(s, 10, 64)
81:			hist = ensure(int(i), hist)
82:			hist[int(i)]++
81:			hist = ensure(int(i), hist)
74:		for scanner.Scan() { //gdb-opt=(scanner/A)
76:			i, err := strconv.ParseInt(s, 10, 64)
77:			if err != nil { //gdb-dbg=(i) //gdb-opt=(err,hist,i)
76:			i, err := strconv.ParseInt(s, 10, 64)
81:			hist = ensure(int(i), hist)
82:			hist[int(i)]++
81:			hist = ensure(int(i), hist)
74:		for scanner.Scan() { //gdb-opt=(scanner/A)
76:			i, err := strconv.ParseInt(s, 10, 64)
77:			if err != nil { //gdb-dbg=(i) //gdb-opt=(err,hist,i)
76:			i, err := strconv.ParseInt(s, 10, 64)
81:			hist = ensure(int(i), hist)
82:			hist[int(i)]++
81:			hist = ensure(int(i), hist)
74:		for scanner.Scan() { //gdb-opt=(scanner/A)
86:		for i, a := range hist {
87:			if a == 0 { //gdb-opt=(a,n,t)
86:		for i, a := range hist {
87:			if a == 0 { //gdb-opt=(a,n,t)
86:		for i, a := range hist {
91:			n += a
90:			t += i * a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
91:			n += a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
90:			t += i * a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
90:			t += i * a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
86:		for i, a := range hist {
90:			t += i * a
91:			n += a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
86:		for i, a := range hist {
87:			if a == 0 { //gdb-opt=(a,n,t)
86:		for i, a := range hist {
91:			n += a
90:			t += i * a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
91:			n += a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
90:			t += i * a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
90:			t += i * a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
86:		for i, a := range hist {
90:			t += i * a
91:			n += a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
86:		for i, a := range hist {
87:			if a == 0 { //gdb-opt=(a,n,t)
86:		for i, a := range hist {
87:			if a == 0 { //gdb-opt=(a,n,t)
86:		for i, a := range hist {
91:			n += a
90:			t += i * a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
91:			n += a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
90:			t += i * a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
90:			t += i * a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
86:		for i, a := range hist {
90:			t += i * a
91:			n += a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
86:		for i, a := range hist {
87:			if a == 0 { //gdb-opt=(a,n,t)
86:		for i, a := range hist {
91:			n += a
90:			t += i * a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
91:			n += a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
90:			t += i * a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
90:			t += i * a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
86:		for i, a := range hist {
90:			t += i * a
91:			n += a
92:			fmt.Fprintf(os.Stderr, "%d\t%d\t%d\t%d\t%d\n", i, a, n, i*a, t) //gdb-dbg=(n,i,t)
86:		for i, a := range hist {
87:			if a == 0 { //gdb-opt=(a,n,t)
86:		for i, a := range hist {
99:	}

src/cmd/compile/internal/ssa/testdata/scopes.dlv-opt.nexts

@@ -4,32 +4,17 @@
24:		y := id(0)
25:		fmt.Println(x)
26:		for i := x; i < 3; i++ {
30:		y = x + y //gdb-dbg=(x,y)//gdb-opt=(x,y)
26:		for i := x; i < 3; i++ {
30:		y = x + y //gdb-dbg=(x,y)//gdb-opt=(x,y)
26:		for i := x; i < 3; i++ {
27:			x := i * i
28:			y += id(x) //gdb-dbg=(x,y)//gdb-opt=(x,y)
26:		for i := x; i < 3; i++ {
28:			y += id(x) //gdb-dbg=(x,y)//gdb-opt=(x,y)
30:		y = x + y //gdb-dbg=(x,y)//gdb-opt=(x,y)
26:		for i := x; i < 3; i++ {
27:			x := i * i
28:			y += id(x) //gdb-dbg=(x,y)//gdb-opt=(x,y)
26:		for i := x; i < 3; i++ {
28:			y += id(x) //gdb-dbg=(x,y)//gdb-opt=(x,y)
30:		y = x + y //gdb-dbg=(x,y)//gdb-opt=(x,y)
26:		for i := x; i < 3; i++ {
27:			x := i * i
28:			y += id(x) //gdb-dbg=(x,y)//gdb-opt=(x,y)
26:		for i := x; i < 3; i++ {
28:			y += id(x) //gdb-dbg=(x,y)//gdb-opt=(x,y)
30:		y = x + y //gdb-dbg=(x,y)//gdb-opt=(x,y)
26:		for i := x; i < 3; i++ {
31:		fmt.Println(x, y)
30:		y = x + y //gdb-dbg=(x,y)//gdb-opt=(x,y)
31:		fmt.Println(x, y)
22:	func test() {
33:		for x := 0; x <= 1; x++ { // From delve scopetest.go
35:			f1(a)
38:				f2(b)
@@ -49,11 +34,9 @@
54:				f = id(2)
56:			for i := 0; i <= 5; i++ {
58:				if i == f {
56:			for i := 0; i <= 5; i++ {
62:				sleepytime()
56:			for i := 0; i <= 5; i++ {
58:				if i == f {
56:			for i := 0; i <= 5; i++ {
62:				sleepytime()
56:			for i := 0; i <= 5; i++ {
58:				if i == f {