diff --git a/.github/SUPPORT b/.github/SUPPORT.md
similarity index 100%
rename from .github/SUPPORT
rename to .github/SUPPORT.md
diff --git a/doc/editors.html b/doc/editors.html
index 1448781036a1f..264f5af920f84 100644
--- a/doc/editors.html
+++ b/doc/editors.html
@@ -19,11 +19,12 @@ <h2 id="options">Options</h2>
 </p>
 
 <ul>
-<li><a href="https://github.com/fatih/vim-go">Vim Go</a>: a plugin for Vim to provide Go programming language support</li>
-<li><a href="https://marketplace.visualstudio.com/items?itemName=lukehoban.Go">Visual Studio Code Go</a>:
-an extension for Visual Studio Code to provide support for the Go programming language</li>
+<li><a href="https://github.com/fatih/vim-go">vim</a>: vim-go plugin provides Go programming language support</li>
+<li><a href="https://marketplace.visualstudio.com/items?itemName=lukehoban.Go">Visual Studio Code</a>:
+Go extension provides support for the Go programming language</li>
 <li><a href="https://www.jetbrains.com/go">Gogland</a>: Gogland is distributed either as a standalone IDE
-or as a plugin for the IntelliJ Platform IDEs</li>
+or as a plugin for the commercial IntelliJ Platform IDEs</li>
+<li><a href="https://atom.io/packages/go-plus">Atom</a>: Go-Plus is an Atom package that provides enhanced Go support</li>
 </ul>
 
 <p>
@@ -41,133 +42,155 @@ <h2 id="options">Options</h2>
 <table class="features-matrix">
   <tr>
     <th></th>
-    <th><img title="Vim Go" src="/doc/editors/vimgo.png"><br>Vim Go</th>
-    <th><img title="Visual Studio Code" src="/doc/editors/vscodego.png"><br>Visual Studio Code Go</th>
+    <th><img title="Vim Go" src="/doc/editors/vimgo.png"><br>vim</th>
+    <th><img title="Visual Studio Code" src="/doc/editors/vscodego.png"><br>Visual Studio Code</th>
     <th><img title="Gogland" src="/doc/editors/gogland.png"><br>Gogland</th>
+    <th><img title="Go-Plus" src="/doc/editors/go-plus.png"><br>Atom</th>
   </tr>
   <tr>
-    <td class="feature-row" colspan="4">Editing features</td>
+    <td class="feature-row" colspan="5">Editing features</td>
   </tr>
   <tr>
     <td>Build and run from the editor/IDE</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
+    <td class="yes">Yes</td>
   </tr>
   <tr>
     <td>Autocompletion of identifers (variable, method, and function names)</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
+    <td class="yes">Yes</td>
   </tr>
   <tr>
-    <td>Autocompletion based on type</td>
+    <td>Type-aware autocompletion</td>
     <td class="no">No</td>
     <td class="no">No</td>
     <td class="yes">Yes</td>
+    <td class="no">No</td>
   </tr>
   <tr>
     <td>Rename identifiers</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
+    <td class="yes">Yes</td>
   </tr>
   <tr>
     <td>Auto format, build, vet, and lint on save</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes<sup>1</sup></td>
+    <td class="yes">Yes</td>
   </tr>
   <tr>
     <td>Auto insert import paths and remove unused on save</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes<sup>2</sup></td>
+    <td class="yes">Yes</td>
   </tr>
   <tr>
     <td>Auto generate JSON, XML tags for struct fields</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
+    <td class="yes">Yes</td>
   </tr>
   <tr>
-    <td class="feature-row" colspan="4">Navigation features</td>
+    <td class="feature-row" colspan="5">Navigation features</td>
   </tr>
   <tr>
     <td>Display documentation inline, or open godoc in browser</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
+    <td class="yes">Yes</td>
   </tr>
   <tr>
     <td>Switch between <code>*.go</code> and <code>*_test.go</code> file</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
+    <td class="yes">No</td>
   </tr>
   <tr>
     <td>Jump to definition and referees</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
+    <td class="yes">Yes</td>
   </tr>
   <tr>
     <td>Look up for interface implementations</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
+    <td class="yes">Yes</td>
   </tr>
   <tr>
     <td>Search for callers and callees</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
+    <td class="yes">Yes</td>
   </tr>
   <tr>
-    <td class="feature-row" colspan="4">Testing and debugging features</td>
+    <td class="feature-row" colspan="5">Testing and debugging features</td>
   </tr>
   <tr>
     <td>Debugger support</td>
     <td class="no">No</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
+    <td class="yes">Yes<sup>3</sup></td>
+
   </tr>
   <tr>
     <td>Run a single test case, all tests from file, or all tests from a package</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
+    <td class="no">No</td>
   </tr>
   <tr>
     <td>Auto generate tests for packages, files and identifiers</td>
     <td class="no">No</td>
     <td class="yes">Yes</td>
     <td class="no">No</td>
+    <td class="no">No</td>
   </tr>
   <tr>
     <td>Debug tests</td>
     <td class="no">No</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
+    <td class="yes">Yes<sup>3</sup></td>
   </tr>
   <tr>
     <td>Display test coverage</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
     <td class="yes">Yes</td>
+    <td class="yes">Yes</td>
   </tr>
   <tr class="download">
     <td></td>
     <td><a href="https://github.com/fatih/vim-go">Install<a/></td>
     <td><a href="https://marketplace.visualstudio.com/items?itemName=lukehoban.Go">Install<a/></td>
     <td><a href="https://www.jetbrains.com/go">Install<a/></td>
+    <td><a href="https://atom.io/packages/go-plus">Install</a></td>
   </tr>
 </table>
 
 <p>
-<sup>1</sup>: Possible when enabled via Settings &gt; Go &gt; On Save, <code>go</code> <code>vet</code> and <code>golint</code> are available via plugins. Also runs tests on save if configured.
+<sup>1</sup>Possible when enabled via Settings &gt; Go &gt; On Save, <code>go</code> <code>vet</code> and <code>golint</code> are available via plugins. Also runs tests on save if configured.
 <br>
-<sup>2</sup>: Additionally, user input can disambiguate when two or more options are available.
+<sup>2</sup>Additionally, user input can disambiguate when two or more options are available.
+<br>
+<sup>3</sup>Available if the <a href="https://atom.io/packages/go-debug">go-debug</a> package is installed.
 </p>
 
 </div>
@@ -206,5 +229,3 @@ <h2 id="options">Options</h2>
   font-weight: bold;
 }
 </style>
-
-<!--TODO(jbd): Add the Atom comparison-->
\ No newline at end of file
diff --git a/doc/editors/go-plus.png b/doc/editors/go-plus.png
new file mode 100644
index 0000000000000..c09c7fe6756a7
Binary files /dev/null and b/doc/editors/go-plus.png differ
diff --git a/doc/go1.9.html b/doc/go1.9.html
index be0ceefcd5c53..7cee379c45cf4 100644
--- a/doc/go1.9.html
+++ b/doc/go1.9.html
@@ -156,6 +156,21 @@ <h3 id="vendor-dotdotdot">Vendor matching with ./...</h3>
   directories, write <code>./vendor/...</code>.
 </p>
 
+<h3 id="goroot">Moved GOROOT</h3>
+
+<p><!-- CL 42533 -->
+  The <a href="/cmd/go/">go tool</a> will now use the path from which it
+  was invoked to attempt to locate the root of the Go install tree.
+  This means that if the entire Go installation is moved to a new
+  location, the go tool should continue to work as usual.
+  This may be overriden by setting <code>GOROOT</code> in the environment,
+  which should only be done in unusual circumstances.
+  Note that this does not affect the result of
+  the <a href="/pkg/runtime/#GOROOT">runtime.GOROOT</a> function, which
+  will continue to report the original installation location;
+  this may be fixed in later releases.
+</p>
+
 <h3 id="compiler">Compiler Toolchain</h3>
 
 <p><!-- CL 37441 -->
@@ -473,6 +488,15 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
       populated.
     </p>
 
+    <p><!-- CL 36696 -->
+
+    If any SAN extension, including with no DSN names, is present
+    in the certificate, then the Common Name from
+    <a href="/pkg/crypto/x509/#Certificate.Subject"><code>Subject</code></a> is ignored.
+    In previous releases, the code tested only whether DNS-name SANs were
+    present in a certificate.
+    </p>
+
 </dl><!-- crypto/x509 -->
 
 <dl id="database/sql"><dt><a href="/pkg/database/sql/">database/sql</a></dt>
@@ -728,7 +752,7 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
       <li><!-- CL 35488 -->
         The <a href="/pkg/net/http/#Transport"><code>Transport</code></a>
         now supports making requests via SOCKS5 proxy when the URL returned by
-        <a href="/net/http/#Transport.Proxy"><code>Transport.Proxy</code></a>
+        <a href="/pkg/net/http/#Transport.Proxy"><code>Transport.Proxy</code></a>
         has the scheme <code>socks5</code>.
       </li>
     </ul>
@@ -764,6 +788,16 @@ <h3 id="minor_library_changes">Minor changes to the library</h3>
 
 </dl><!-- net/http/httptest -->
 
+<dl id="net/http/httputil"><dt><a href="/pkg/net/http/httputil/">net/http/httputil</a></dt>
+  <dd>
+    <p><!-- CL 43712 -->
+      The <a href="/pkg/net/http/httputil/#ReverseProxy"><code>ReverseProxy</code></a>
+      now proxies all HTTP/2 response trailers, even those not declared in the initial response
+      header. Such undeclared trailers are used by the gRPC protocol.
+    </p>
+
+</dl><!-- net/http/httputil -->
+
 <dl id="os"><dt><a href="/pkg/os/">os</a></dt>
   <dd>
     <p><!-- CL 36800 -->
diff --git a/doc/root.html b/doc/root.html
index 27dbc74ab67d3..9bdf927480407 100644
--- a/doc/root.html
+++ b/doc/root.html
@@ -6,7 +6,9 @@
 <div class="left">
 
 <div id="learn">
+{{if not $.GoogleCN}}
 <a class="popout share">Pop-out</a>
+{{end}}
 <div class="rootHeading">Try Go</div>
 <div class="input">
 <textarea spellcheck="false" class="code">// You can edit this code!
@@ -26,10 +28,10 @@
 </div>
 <div class="buttons">
 <a class="run" href="#" title="Run this code [shift-enter]">Run</a>
-{{if $.Share}}
+{{if not $.GoogleCN}}
 <a class="share" href="#" title="Share this code">Share</a>
-{{end}}
 <a class="tour" href="//tour.golang.org/" title="Learn Go from your browser">Tour</a>
+{{end}}
 </div>
 <div class="toys">
 <select>
@@ -68,85 +70,91 @@
 
 <div style="clear: both"></div>
 
+{{if not $.GoogleCN}}
 <div class="left">
-
-<div id="video">
-<div class="rootHeading">Featured video</div>
-<iframe width="415" height="241" src="//www.youtube.com/embed/ytEkHepK08c" frameborder="0" allowfullscreen></iframe>
-</div>
-
+  <div id="video">
+    <div class="rootHeading">Featured video</div>
+    <iframe width="415" height="241" src="//www.youtube.com/embed/ytEkHepK08c" frameborder="0" allowfullscreen></iframe>
+  </div>
 </div>
 
 <div class="right">
-
-<div id="blog">
-<div class="rootHeading">Featured articles</div>
-<div class="read"><a href="//blog.golang.org/">Read more</a></div>
-</div>
-
+	<div id="blog">
+		<div class="rootHeading">Featured articles</div>
+		<div class="read"><a href="//blog.golang.org/">Read more</a></div>
+	</div>
 </div>
+{{end}}
 
 <div style="clear: both;"></div>
 
-<script type="text/javascript">
-
-function readableTime(t) {
-	var m = ["January", "February", "March", "April", "May", "June", "July",
-		"August", "September", "October", "November", "December"];
-	var p = t.substring(0, t.indexOf("T")).split("-");
-	var d = new Date(p[0], p[1]-1, p[2]);
-	return d.getDate() + " " + m[d.getMonth()] + " " + d.getFullYear();
-}
-
-function feedLoaded(result) {
-	var blog = document.getElementById("blog");
-	var read = blog.getElementsByClassName("read")[0];
-	for (var i = 0; i < result.length && i < 2; i++) {
-		var entry = result[i];
-		var title = document.createElement("a");
-		title.className = "title";
-		title.href = entry.Link;
-		title.innerHTML = entry.Title;
-		blog.insertBefore(title, read);
-		var extract = document.createElement("div");
-		extract.className = "extract";
-		extract.innerHTML = entry.Summary;
-		blog.insertBefore(extract, read);
-		var when = document.createElement("div");
-		when.className = "when";
-		when.innerHTML = "Published " + readableTime(entry.Time);
-		blog.insertBefore(when, read);
-	}
-}
-
-window.initFuncs.push(function() {
-	// Set up playground if enabled.
-	if (window.playground) {
-		window.playground({
-			"codeEl":        "#learn .code",
-			"outputEl":      "#learn .output",
-			"runEl":         "#learn .run",
-			"shareEl":       "#learn .share",
-			"shareRedirect": "//play.golang.org/p/",
-			"toysEl":        "#learn .toys select"
-		});
-	} else {
-		$('#learn').hide()
+<script>
+(function() {
+	'use strict';
+
+	window.initFuncs.push(function() {
+		// Set up playground if enabled.
+		if (window.playground) {
+			window.playground({
+				"codeEl":        "#learn .code",
+				"outputEl":      "#learn .output",
+				"runEl":         "#learn .run",
+				"shareEl":       "#learn .share",
+				"shareRedirect": "//play.golang.org/p/",
+				"toysEl":        "#learn .toys select"
+			});
+		} else {
+			$('#learn').hide()
+		}
+	});
+
+	{{if not $.GoogleCN}}
+
+	function readableTime(t) {
+		var m = ["January", "February", "March", "April", "May", "June", "July",
+			"August", "September", "October", "November", "December"];
+		var p = t.substring(0, t.indexOf("T")).split("-");
+		var d = new Date(p[0], p[1]-1, p[2]);
+		return d.getDate() + " " + m[d.getMonth()] + " " + d.getFullYear();
 	}
 
-	// Load blog feed.
-	$('<script/>').attr('text', 'text/javascript')
-		.attr('src', '//blog.golang.org/.json?jsonp=feedLoaded')
-		.appendTo('body');
-
-	// Set the video at random.
-	var videos = [
-		{h: 241, s: "//www.youtube.com/embed/ytEkHepK08c"}, // Tour of Go
-		{h: 241, s: "//www.youtube.com/embed/f6kdp27TYZs"}, // Concurrency Patterns
-		{h: 233, s: "//player.vimeo.com/video/69237265"}    // Simple environment
-	];
-	var v = videos[Math.floor(Math.random()*videos.length)];
-	$('#video iframe').attr('height', v.h).attr('src', v.s);
-});
+	window.feedLoaded = function(result) {
+		var blog = document.getElementById("blog");
+		var read = blog.getElementsByClassName("read")[0];
+		for (var i = 0; i < result.length && i < 2; i++) {
+			var entry = result[i];
+			var title = document.createElement("a");
+			title.className = "title";
+			title.href = entry.Link;
+			title.innerHTML = entry.Title;
+			blog.insertBefore(title, read);
+			var extract = document.createElement("div");
+			extract.className = "extract";
+			extract.innerHTML = entry.Summary;
+			blog.insertBefore(extract, read);
+			var when = document.createElement("div");
+			when.className = "when";
+			when.innerHTML = "Published " + readableTime(entry.Time);
+			blog.insertBefore(when, read);
+		}
+	}
 
+	window.initFuncs.push(function() {
+		// Load blog feed.
+		$('<script/>').attr('text', 'text/javascript')
+			.attr('src', '//blog.golang.org/.json?jsonp=feedLoaded')
+			.appendTo('body');
+
+		// Set the video at random.
+		var videos = [
+			{h: 241, s: "//www.youtube.com/embed/ytEkHepK08c"}, // Tour of Go
+			{h: 241, s: "//www.youtube.com/embed/f6kdp27TYZs"}, // Concurrency Patterns
+			{h: 233, s: "//player.vimeo.com/video/69237265"}    // Simple environment
+		];
+		var v = videos[Math.floor(Math.random()*videos.length)];
+		$('#video iframe').attr('height', v.h).attr('src', v.s);
+	});
+
+	{{end}}
+})();
 </script>
diff --git a/misc/cgo/errors/ptr.go b/misc/cgo/errors/ptr.go
index 4dafbdf3c0117..3e117666bffb5 100644
--- a/misc/cgo/errors/ptr.go
+++ b/misc/cgo/errors/ptr.go
@@ -343,6 +343,14 @@ var ptrTests = []ptrTest{
 		body:    `var b C.char; p := &b; C.f((*C.u)(unsafe.Pointer(&p)))`,
 		fail:    false,
 	},
+	{
+		// Issue #21306.
+		name:    "preempt-during-call",
+		c:       `void f() {}`,
+		imports: []string{"runtime", "sync"},
+		body:    `var wg sync.WaitGroup; wg.Add(100); for i := 0; i < 100; i++ { go func(i int) { for j := 0; j < 100; j++ { C.f(); runtime.GOMAXPROCS(i) }; wg.Done() }(i) }; wg.Wait()`,
+		fail:    false,
+	},
 }
 
 func main() {
diff --git a/misc/cgo/testsanitizers/test.bash b/misc/cgo/testsanitizers/test.bash
index ea08f374325cb..9f80af6c50755 100755
--- a/misc/cgo/testsanitizers/test.bash
+++ b/misc/cgo/testsanitizers/test.bash
@@ -156,15 +156,18 @@ if test "$tsan" = "yes"; then
     if ! $CC -fsanitize=thread ${TMPDIR}/testsanitizers$$.c -o ${TMPDIR}/testsanitizers$$ &> ${TMPDIR}/testsanitizers$$.err; then
 	ok=no
     fi
-     if grep "unrecognized" ${TMPDIR}/testsanitizers$$.err >& /dev/null; then
+    if grep "unrecognized" ${TMPDIR}/testsanitizers$$.err >& /dev/null; then
 	echo "skipping tsan tests: -fsanitize=thread not supported"
 	tsan=no
-     elif test "$ok" != "yes"; then
-	 cat ${TMPDIR}/testsanitizers$$.err
-	 echo "skipping tsan tests: -fsanitizer=thread build failed"
-	 tsan=no
-     fi
-     rm -f ${TMPDIR}/testsanitizers$$*
+    elif test "$ok" != "yes"; then
+	cat ${TMPDIR}/testsanitizers$$.err
+	echo "skipping tsan tests: -fsanitizer=thread build failed"
+	tsan=no
+    elif ! ${TMPDIR}/testsanitizers$$ 2>&1; then
+	echo "skipping tsan tests: running tsan program failed"
+	tsan=no
+    fi
+    rm -f ${TMPDIR}/testsanitizers$$*
 fi
 
 # Run a TSAN test.
@@ -196,8 +199,10 @@ if test "$tsan" = "yes"; then
     # These tests are only reliable using clang or GCC version 7 or later.
     # Otherwise runtime/cgo/libcgo.h can't tell whether TSAN is in use.
     ok=false
+    clang=false
     if ${CC} --version | grep clang >/dev/null 2>&1; then
 	ok=true
+	clang=true
     else
 	ver=$($CC -dumpversion)
 	major=$(echo $ver | sed -e 's/\([0-9]*\).*/\1/')
@@ -213,9 +218,13 @@ if test "$tsan" = "yes"; then
 	testtsan tsan5.go "CGO_CFLAGS=-fsanitize=thread CGO_LDFLAGS=-fsanitize=thread" "-installsuffix=tsan"
 	testtsan tsan6.go "CGO_CFLAGS=-fsanitize=thread CGO_LDFLAGS=-fsanitize=thread" "-installsuffix=tsan"
 	testtsan tsan7.go "CGO_CFLAGS=-fsanitize=thread CGO_LDFLAGS=-fsanitize=thread" "-installsuffix=tsan"
-	testtsan tsan10.go "CGO_CFLAGS=-fsanitize=thread CGO_LDFLAGS=-fsanitize=thread" "-installsuffix=tsan"
-	testtsan tsan11.go "CGO_CFLAGS=-fsanitize=thread CGO_LDFLAGS=-fsanitize=thread" "-installsuffix=tsan"
-	testtsan tsan12.go "CGO_CFLAGS=-fsanitize=thread CGO_LDFLAGS=-fsanitize=thread" "-installsuffix=tsan"
+
+	# The remaining tests reportedly hang when built with GCC; issue #21196.
+	if test "$clang" = "true"; then
+	    testtsan tsan10.go "CGO_CFLAGS=-fsanitize=thread CGO_LDFLAGS=-fsanitize=thread" "-installsuffix=tsan"
+	    testtsan tsan11.go "CGO_CFLAGS=-fsanitize=thread CGO_LDFLAGS=-fsanitize=thread" "-installsuffix=tsan"
+	    testtsan tsan12.go "CGO_CFLAGS=-fsanitize=thread CGO_LDFLAGS=-fsanitize=thread" "-installsuffix=tsan"
+	fi
 
 	testtsanshared
     fi
diff --git a/src/cmd/compile/internal/arm/ssa.go b/src/cmd/compile/internal/arm/ssa.go
index 343f2d3aec7da..93abee3da0f09 100644
--- a/src/cmd/compile/internal/arm/ssa.go
+++ b/src/cmd/compile/internal/arm/ssa.go
@@ -464,6 +464,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 	case ssa.OpARMMOVWaddr:
 		p := s.Prog(arm.AMOVW)
 		p.From.Type = obj.TYPE_ADDR
+		p.From.Reg = v.Args[0].Reg()
 		p.To.Type = obj.TYPE_REG
 		p.To.Reg = v.Reg()
 
@@ -485,7 +486,6 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 		case nil:
 			// No sym, just MOVW $off(SP), R
 			wantreg = "SP"
-			p.From.Reg = arm.REGSP
 			p.From.Offset = v.AuxInt
 		}
 		if reg := v.Args[0].RegName(); reg != wantreg {
diff --git a/src/cmd/compile/internal/arm64/ssa.go b/src/cmd/compile/internal/arm64/ssa.go
index dec6a4e93ede5..0f9e82c727db3 100644
--- a/src/cmd/compile/internal/arm64/ssa.go
+++ b/src/cmd/compile/internal/arm64/ssa.go
@@ -260,6 +260,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 	case ssa.OpARM64MOVDaddr:
 		p := s.Prog(arm64.AMOVD)
 		p.From.Type = obj.TYPE_ADDR
+		p.From.Reg = v.Args[0].Reg()
 		p.To.Type = obj.TYPE_REG
 		p.To.Reg = v.Reg()
 
@@ -281,7 +282,6 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 		case nil:
 			// No sym, just MOVD $off(SP), R
 			wantreg = "SP"
-			p.From.Reg = arm64.REGSP
 			p.From.Offset = v.AuxInt
 		}
 		if reg := v.Args[0].RegName(); reg != wantreg {
diff --git a/src/cmd/compile/internal/gc/asm_test.go b/src/cmd/compile/internal/gc/asm_test.go
index 221b8497f1598..08ec638f44ef7 100644
--- a/src/cmd/compile/internal/gc/asm_test.go
+++ b/src/cmd/compile/internal/gc/asm_test.go
@@ -898,6 +898,17 @@ var linuxAMD64Tests = []*asmTest{
 		}`,
 		[]string{"\tCMPL\t[A-Z]"},
 	},
+	{
+		// make sure assembly output has matching offset and base register.
+		`
+		func f72(a, b int) int {
+			var x [16]byte // use some frame
+			_ = x
+			return b
+		}
+		`,
+		[]string{"b\\+40\\(SP\\)"},
+	},
 }
 
 var linux386Tests = []*asmTest{
@@ -1302,6 +1313,17 @@ var linuxARMTests = []*asmTest{
 		`,
 		[]string{"\tCLZ\t"},
 	},
+	{
+		// make sure assembly output has matching offset and base register.
+		`
+		func f13(a, b int) int {
+			var x [16]byte // use some frame
+			_ = x
+			return b
+		}
+		`,
+		[]string{"b\\+4\\(FP\\)"},
+	},
 }
 
 var linuxARM64Tests = []*asmTest{
@@ -1473,7 +1495,7 @@ var linuxARM64Tests = []*asmTest{
 			return
 		}
 		`,
-		[]string{"\tMOVD\t\"\"\\.a\\+[0-9]+\\(RSP\\), R[0-9]+", "\tMOVD\tR[0-9]+, \"\"\\.b\\+[0-9]+\\(RSP\\)"},
+		[]string{"\tMOVD\t\"\"\\.a\\+[0-9]+\\(FP\\), R[0-9]+", "\tMOVD\tR[0-9]+, \"\"\\.b\\+[0-9]+\\(FP\\)"},
 	},
 }
 
diff --git a/src/cmd/compile/internal/mips/ssa.go b/src/cmd/compile/internal/mips/ssa.go
index d2b4885eaad9c..e65515a85b010 100644
--- a/src/cmd/compile/internal/mips/ssa.go
+++ b/src/cmd/compile/internal/mips/ssa.go
@@ -273,6 +273,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 	case ssa.OpMIPSMOVWaddr:
 		p := s.Prog(mips.AMOVW)
 		p.From.Type = obj.TYPE_ADDR
+		p.From.Reg = v.Args[0].Reg()
 		var wantreg string
 		// MOVW $sym+off(base), R
 		// the assembler expands it as the following:
@@ -291,7 +292,6 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 		case nil:
 			// No sym, just MOVW $off(SP), R
 			wantreg = "SP"
-			p.From.Reg = mips.REGSP
 			p.From.Offset = v.AuxInt
 		}
 		if reg := v.Args[0].RegName(); reg != wantreg {
diff --git a/src/cmd/compile/internal/mips64/ssa.go b/src/cmd/compile/internal/mips64/ssa.go
index 5a7a6019422b1..db163f3e9d077 100644
--- a/src/cmd/compile/internal/mips64/ssa.go
+++ b/src/cmd/compile/internal/mips64/ssa.go
@@ -247,6 +247,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 	case ssa.OpMIPS64MOVVaddr:
 		p := s.Prog(mips.AMOVV)
 		p.From.Type = obj.TYPE_ADDR
+		p.From.Reg = v.Args[0].Reg()
 		var wantreg string
 		// MOVV $sym+off(base), R
 		// the assembler expands it as the following:
@@ -265,7 +266,6 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 		case nil:
 			// No sym, just MOVV $off(SP), R
 			wantreg = "SP"
-			p.From.Reg = mips.REGSP
 			p.From.Offset = v.AuxInt
 		}
 		if reg := v.Args[0].RegName(); reg != wantreg {
diff --git a/src/cmd/compile/internal/ppc64/ssa.go b/src/cmd/compile/internal/ppc64/ssa.go
index a95dabccf0be1..5fe140fdcf16e 100644
--- a/src/cmd/compile/internal/ppc64/ssa.go
+++ b/src/cmd/compile/internal/ppc64/ssa.go
@@ -638,6 +638,7 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 	case ssa.OpPPC64MOVDaddr:
 		p := s.Prog(ppc64.AMOVD)
 		p.From.Type = obj.TYPE_ADDR
+		p.From.Reg = v.Args[0].Reg()
 		p.To.Type = obj.TYPE_REG
 		p.To.Reg = v.Reg()
 
@@ -660,7 +661,6 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
 		case nil:
 			// No sym, just MOVD $off(SP), R
 			wantreg = "SP"
-			p.From.Reg = ppc64.REGSP
 			p.From.Offset = v.AuxInt
 		}
 		if reg := v.Args[0].RegName(); reg != wantreg {
diff --git a/src/cmd/go/go_test.go b/src/cmd/go/go_test.go
index e706e27bdf366..7d80d965ae6dc 100644
--- a/src/cmd/go/go_test.go
+++ b/src/cmd/go/go_test.go
@@ -4314,3 +4314,20 @@ func TestTestRegexps(t *testing.T) {
 		t.Errorf("reduced output:<<<\n%s>>> want:<<<\n%s>>>", have, want)
 	}
 }
+
+func TestListTests(t *testing.T) {
+	var tg *testgoData
+	testWith := func(listName, expected string) func(*testing.T) {
+		return func(t *testing.T) {
+			tg = testgo(t)
+			defer tg.cleanup()
+			tg.run("test", "./testdata/src/testlist/...", fmt.Sprintf("-list=%s", listName))
+			tg.grepStdout(expected, fmt.Sprintf("-test.list=%s returned %q, expected %s", listName, tg.getStdout(), expected))
+		}
+	}
+
+	t.Run("Test", testWith("Test", "TestSimple"))
+	t.Run("Bench", testWith("Benchmark", "BenchmarkSimple"))
+	t.Run("Example1", testWith("Example", "ExampleSimple"))
+	t.Run("Example2", testWith("Example", "ExampleWithEmptyOutput"))
+}
diff --git a/src/cmd/go/testdata/src/testlist/bench_test.go b/src/cmd/go/testdata/src/testlist/bench_test.go
new file mode 100644
index 0000000000000..22f147b63390d
--- /dev/null
+++ b/src/cmd/go/testdata/src/testlist/bench_test.go
@@ -0,0 +1,14 @@
+package testlist
+
+import (
+	"fmt"
+	"testing"
+)
+
+func BenchmarkSimplefunc(b *testing.B) {
+	b.StopTimer()
+	b.StartTimer()
+	for i := 0; i < b.N; i++ {
+		_ = fmt.Sprint("Test for bench")
+	}
+}
diff --git a/src/cmd/go/testdata/src/testlist/example_test.go b/src/cmd/go/testdata/src/testlist/example_test.go
new file mode 100644
index 0000000000000..0298dfde81e2a
--- /dev/null
+++ b/src/cmd/go/testdata/src/testlist/example_test.go
@@ -0,0 +1,21 @@
+package testlist
+
+import (
+	"fmt"
+)
+
+func ExampleSimple() {
+	fmt.Println("Test with Output.")
+
+	// Output: Test with Output.
+}
+
+func ExampleWithEmptyOutput() {
+	fmt.Println("")
+
+	// Output:
+}
+
+func ExampleNoOutput() {
+	_ = fmt.Sprint("Test with no output")
+}
diff --git a/src/cmd/go/testdata/src/testlist/test_test.go b/src/cmd/go/testdata/src/testlist/test_test.go
new file mode 100644
index 0000000000000..bdc09f27c5b10
--- /dev/null
+++ b/src/cmd/go/testdata/src/testlist/test_test.go
@@ -0,0 +1,10 @@
+package testlist
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestSimple(t *testing.T) {
+	_ = fmt.Sprint("Test simple")
+}
diff --git a/src/cmd/internal/obj/arm/asm5.go b/src/cmd/internal/obj/arm/asm5.go
index cfda99f60289b..8abf732b2caf7 100644
--- a/src/cmd/internal/obj/arm/asm5.go
+++ b/src/cmd/internal/obj/arm/asm5.go
@@ -1167,6 +1167,11 @@ func (c *ctxt5) aclass(a *obj.Addr) int {
 			return C_ADDR
 
 		case obj.NAME_AUTO:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-SP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = c.autosize + a.Offset
 			if t := immaddr(int32(c.instoffset)); t != 0 {
 				if immhalf(int32(c.instoffset)) {
@@ -1185,6 +1190,11 @@ func (c *ctxt5) aclass(a *obj.Addr) int {
 			return C_LAUTO
 
 		case obj.NAME_PARAM:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-FP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = c.autosize + a.Offset + 4
 			if t := immaddr(int32(c.instoffset)); t != 0 {
 				if immhalf(int32(c.instoffset)) {
@@ -1285,10 +1295,20 @@ func (c *ctxt5) aclass(a *obj.Addr) int {
 			return C_LCONADDR
 
 		case obj.NAME_AUTO:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-SP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = c.autosize + a.Offset
 			return c.aconsize()
 
 		case obj.NAME_PARAM:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-FP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = c.autosize + a.Offset + 4
 			return c.aconsize()
 		}
diff --git a/src/cmd/internal/obj/arm64/asm7.go b/src/cmd/internal/obj/arm64/asm7.go
index 04a481863ad6f..4419909f69149 100644
--- a/src/cmd/internal/obj/arm64/asm7.go
+++ b/src/cmd/internal/obj/arm64/asm7.go
@@ -1149,10 +1149,20 @@ func (c *ctxt7) aclass(a *obj.Addr) int {
 			return C_GOTADDR
 
 		case obj.NAME_AUTO:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-SP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset
 			return autoclass(c.instoffset)
 
 		case obj.NAME_PARAM:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-FP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset + 8
 			return autoclass(c.instoffset)
 
@@ -1228,10 +1238,20 @@ func (c *ctxt7) aclass(a *obj.Addr) int {
 			return C_VCONADDR
 
 		case obj.NAME_AUTO:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-SP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset
 			goto aconsize
 
 		case obj.NAME_PARAM:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-FP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset + 8
 			goto aconsize
 		}
diff --git a/src/cmd/internal/obj/mips/asm0.go b/src/cmd/internal/obj/mips/asm0.go
index 3cfb260d60398..6257e5b83d2a0 100644
--- a/src/cmd/internal/obj/mips/asm0.go
+++ b/src/cmd/internal/obj/mips/asm0.go
@@ -556,6 +556,11 @@ func (c *ctxt0) aclass(a *obj.Addr) int {
 			return C_LEXT
 
 		case obj.NAME_AUTO:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-SP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset
 			if c.instoffset >= -BIG && c.instoffset < BIG {
 				return C_SAUTO
@@ -563,6 +568,11 @@ func (c *ctxt0) aclass(a *obj.Addr) int {
 			return C_LAUTO
 
 		case obj.NAME_PARAM:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-FP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset + c.ctxt.FixedFrameSize()
 			if c.instoffset >= -BIG && c.instoffset < BIG {
 				return C_SAUTO
@@ -616,6 +626,11 @@ func (c *ctxt0) aclass(a *obj.Addr) int {
 			return C_LECON
 
 		case obj.NAME_AUTO:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-SP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset
 			if c.instoffset >= -BIG && c.instoffset < BIG {
 				return C_SACON
@@ -623,6 +638,11 @@ func (c *ctxt0) aclass(a *obj.Addr) int {
 			return C_LACON
 
 		case obj.NAME_PARAM:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-FP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset + c.ctxt.FixedFrameSize()
 			if c.instoffset >= -BIG && c.instoffset < BIG {
 				return C_SACON
diff --git a/src/cmd/internal/obj/ppc64/asm9.go b/src/cmd/internal/obj/ppc64/asm9.go
index bdbac03f9c043..4d787b1c352ee 100644
--- a/src/cmd/internal/obj/ppc64/asm9.go
+++ b/src/cmd/internal/obj/ppc64/asm9.go
@@ -758,6 +758,11 @@ func (c *ctxt9) aclass(a *obj.Addr) int {
 			return C_GOTADDR
 
 		case obj.NAME_AUTO:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-SP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset
 			if c.instoffset >= -BIG && c.instoffset < BIG {
 				return C_SAUTO
@@ -765,6 +770,11 @@ func (c *ctxt9) aclass(a *obj.Addr) int {
 			return C_LAUTO
 
 		case obj.NAME_PARAM:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-FP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset + c.ctxt.FixedFrameSize()
 			if c.instoffset >= -BIG && c.instoffset < BIG {
 				return C_SAUTO
@@ -817,6 +827,11 @@ func (c *ctxt9) aclass(a *obj.Addr) int {
 			return C_LCON
 
 		case obj.NAME_AUTO:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-SP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset
 			if c.instoffset >= -BIG && c.instoffset < BIG {
 				return C_SACON
@@ -824,6 +839,11 @@ func (c *ctxt9) aclass(a *obj.Addr) int {
 			return C_LACON
 
 		case obj.NAME_PARAM:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-FP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset + c.ctxt.FixedFrameSize()
 			if c.instoffset >= -BIG && c.instoffset < BIG {
 				return C_SACON
diff --git a/src/cmd/internal/obj/s390x/asmz.go b/src/cmd/internal/obj/s390x/asmz.go
index 3bba7b2a5ce90..6d2b870f0aca9 100644
--- a/src/cmd/internal/obj/s390x/asmz.go
+++ b/src/cmd/internal/obj/s390x/asmz.go
@@ -505,6 +505,11 @@ func (c *ctxtz) aclass(a *obj.Addr) int {
 			return C_GOTADDR
 
 		case obj.NAME_AUTO:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-SP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset
 			if c.instoffset >= -BIG && c.instoffset < BIG {
 				return C_SAUTO
@@ -512,6 +517,11 @@ func (c *ctxtz) aclass(a *obj.Addr) int {
 			return C_LAUTO
 
 		case obj.NAME_PARAM:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-FP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset + c.ctxt.FixedFrameSize()
 			if c.instoffset >= -BIG && c.instoffset < BIG {
 				return C_SAUTO
@@ -567,6 +577,11 @@ func (c *ctxtz) aclass(a *obj.Addr) int {
 			return C_SYMADDR
 
 		case obj.NAME_AUTO:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-SP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset
 			if c.instoffset >= -BIG && c.instoffset < BIG {
 				return C_SACON
@@ -574,6 +589,11 @@ func (c *ctxtz) aclass(a *obj.Addr) int {
 			return C_LACON
 
 		case obj.NAME_PARAM:
+			if a.Reg == REGSP {
+				// unset base register for better printing, since
+				// a.Offset is still relative to pseudo-FP.
+				a.Reg = obj.REG_NONE
+			}
 			c.instoffset = int64(c.autosize) + a.Offset + c.ctxt.FixedFrameSize()
 			if c.instoffset >= -BIG && c.instoffset < BIG {
 				return C_SACON
diff --git a/src/cmd/vet/main.go b/src/cmd/vet/main.go
index 77376c90ed16b..34c5297b89f9e 100644
--- a/src/cmd/vet/main.go
+++ b/src/cmd/vet/main.go
@@ -349,8 +349,9 @@ func doPackage(directory string, names []string, basePkg *Package) *Package {
 	pkg.files = files
 	// Type check the package.
 	err := pkg.check(fs, astFiles)
-	if err != nil && *verbose {
-		warnf("%s", err)
+	if err != nil {
+		// Note that we only report this error when *verbose.
+		Println(err)
 	}
 
 	// Check.
diff --git a/src/cmd/vet/testdata/cgo/cgo3.go b/src/cmd/vet/testdata/cgo/cgo3.go
new file mode 100644
index 0000000000000..0b1518e1f930a
--- /dev/null
+++ b/src/cmd/vet/testdata/cgo/cgo3.go
@@ -0,0 +1,13 @@
+// Copyright 2017 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.
+
+// Used by TestVetVerbose to test that vet -v doesn't fail because it
+// can't find "C".
+
+package testdata
+
+import "C"
+
+func F() {
+}
diff --git a/src/cmd/vet/vet_test.go b/src/cmd/vet/vet_test.go
index b3d5c663a714c..8db8ff4d20266 100644
--- a/src/cmd/vet/vet_test.go
+++ b/src/cmd/vet/vet_test.go
@@ -205,3 +205,15 @@ func TestTags(t *testing.T) {
 		})
 	}
 }
+
+// Issue #21188.
+func TestVetVerbose(t *testing.T) {
+	t.Parallel()
+	Build(t)
+	cmd := exec.Command("./"+binary, "-v", "-all", "testdata/cgo/cgo3.go")
+	out, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Logf("%s", out)
+		t.Error(err)
+	}
+}
diff --git a/src/encoding/binary/example_test.go b/src/encoding/binary/example_test.go
index 2b52a47d129cf..a8b8dba650770 100644
--- a/src/encoding/binary/example_test.go
+++ b/src/encoding/binary/example_test.go
@@ -68,3 +68,94 @@ func ExampleByteOrder_get() {
 	// Output:
 	// 0x03e8 0x07d0
 }
+
+func ExamplePutUvarint() {
+	buf := make([]byte, binary.MaxVarintLen64)
+
+	for _, x := range []uint64{1, 2, 127, 128, 255, 256} {
+		n := binary.PutUvarint(buf, x)
+		fmt.Printf("%x\n", buf[:n])
+	}
+	// Output:
+	// 01
+	// 02
+	// 7f
+	// 8001
+	// ff01
+	// 8002
+}
+
+func ExamplePutVarint() {
+	buf := make([]byte, binary.MaxVarintLen64)
+
+	for _, x := range []int64{-65, -64, -2, -1, 0, 1, 2, 63, 64} {
+		n := binary.PutVarint(buf, x)
+		fmt.Printf("%x\n", buf[:n])
+	}
+	// Output:
+	// 8101
+	// 7f
+	// 03
+	// 01
+	// 00
+	// 02
+	// 04
+	// 7e
+	// 8001
+}
+
+func ExampleUvarint() {
+	inputs := [][]byte{
+		[]byte{0x01},
+		[]byte{0x02},
+		[]byte{0x7f},
+		[]byte{0x80, 0x01},
+		[]byte{0xff, 0x01},
+		[]byte{0x80, 0x02},
+	}
+	for _, b := range inputs {
+		x, n := binary.Uvarint(b)
+		if n != len(b) {
+			fmt.Println("Uvarint did not consume all of in")
+		}
+		fmt.Println(x)
+	}
+	// Output:
+	// 1
+	// 2
+	// 127
+	// 128
+	// 255
+	// 256
+}
+
+func ExampleVarint() {
+	inputs := [][]byte{
+		[]byte{0x81, 0x01},
+		[]byte{0x7f},
+		[]byte{0x03},
+		[]byte{0x01},
+		[]byte{0x00},
+		[]byte{0x02},
+		[]byte{0x04},
+		[]byte{0x7e},
+		[]byte{0x80, 0x01},
+	}
+	for _, b := range inputs {
+		x, n := binary.Varint(b)
+		if n != len(b) {
+			fmt.Println("Varint did not consume all of in")
+		}
+		fmt.Println(x)
+	}
+	// Output:
+	// -65
+	// -64
+	// -2
+	// -1
+	// 0
+	// 1
+	// 2
+	// 63
+	// 64
+}
diff --git a/src/go/ast/ast.go b/src/go/ast/ast.go
index 77ef98ceaf9d2..9ab7b1e62568f 100644
--- a/src/go/ast/ast.go
+++ b/src/go/ast/ast.go
@@ -969,14 +969,14 @@ func (*FuncDecl) declNode() {}
 //
 // For correct printing of source code containing comments (using packages
 // go/format and go/printer), special care must be taken to update comments
-// when a File's syntax tree is modified: For printing, comments are inter-
-// spersed between tokens based on their position. If syntax tree nodes are
+// when a File's syntax tree is modified: For printing, comments are interspersed
+// between tokens based on their position. If syntax tree nodes are
 // removed or moved, relevant comments in their vicinity must also be removed
 // (from the File.Comments list) or moved accordingly (by updating their
 // positions). A CommentMap may be used to facilitate some of these operations.
 //
-// Whether and how a comment is associated with a node depends on the inter-
-// pretation of the syntax tree by the manipulating program: Except for Doc
+// Whether and how a comment is associated with a node depends on the
+// interpretation of the syntax tree by the manipulating program: Except for Doc
 // and Comment comments directly associated with nodes, the remaining comments
 // are "free-floating" (see also issues #18593, #20744).
 //
diff --git a/src/go/parser/parser.go b/src/go/parser/parser.go
index 1b4309b5da739..2b58724521fb4 100644
--- a/src/go/parser/parser.go
+++ b/src/go/parser/parser.go
@@ -1707,8 +1707,8 @@ func (p *parser) parseSimpleStmt(mode int) (ast.Stmt, bool) {
 		}
 		// The label declaration typically starts at x[0].Pos(), but the label
 		// declaration may be erroneous due to a token after that position (and
-		// before the ':'). If SpuriousErrors is not set, the (only) error re-
-		// ported for the line is the illegal label error instead of the token
+		// before the ':'). If SpuriousErrors is not set, the (only) error
+		// reported for the line is the illegal label error instead of the token
 		// before the ':' that caused the problem. Thus, use the (latest) colon
 		// position for error reporting.
 		p.error(colon, "illegal label declaration")
diff --git a/src/internal/poll/fd_windows.go b/src/internal/poll/fd_windows.go
index 9f40886d08b07..655f9348c6223 100644
--- a/src/internal/poll/fd_windows.go
+++ b/src/internal/poll/fd_windows.go
@@ -154,6 +154,10 @@ func (s *ioSrv) ProcessRemoteIO() {
 // is available. Alternatively, it passes the request onto
 // runtime netpoll and waits for completion or cancels request.
 func (s *ioSrv) ExecIO(o *operation, submit func(o *operation) error) (int, error) {
+	if o.fd.pd.runtimeCtx == 0 {
+		return 0, errors.New("internal error: polling on unsupported descriptor type")
+	}
+
 	if !canCancelIO {
 		onceStartServer.Do(startServer)
 	}
@@ -315,8 +319,21 @@ func (fd *FD) Init(net string) (string, error) {
 		return "", errors.New("internal error: unknown network type " + net)
 	}
 
-	if err := fd.pd.init(fd); err != nil {
-		return "", err
+	if !fd.isFile && !fd.isConsole && !fd.isDir {
+		// Only call init for a network socket.
+		// This means that we don't add files to the runtime poller.
+		// Adding files to the runtime poller can confuse matters
+		// if the user is doing their own overlapped I/O.
+		// See issue #21172.
+		//
+		// In general the code below avoids calling the ExecIO
+		// method for non-network sockets. If some method does
+		// somehow call ExecIO, then ExecIO, and therefore the
+		// calling method, will return an error, because
+		// fd.pd.runtimeCtx will be 0.
+		if err := fd.pd.init(fd); err != nil {
+			return "", err
+		}
 	}
 	if hasLoadSetFileCompletionNotificationModes {
 		// We do not use events, so we can skip them always.
diff --git a/src/math/big/ratconv.go b/src/math/big/ratconv.go
index a6a401c857656..4bc6ef7e8063e 100644
--- a/src/math/big/ratconv.go
+++ b/src/math/big/ratconv.go
@@ -40,8 +40,8 @@ func (z *Rat) Scan(s fmt.ScanState, ch rune) error {
 // SetString sets z to the value of s and returns z and a boolean indicating
 // success. s can be given as a fraction "a/b" or as a floating-point number
 // optionally followed by an exponent. The entire string (not just a prefix)
-// must be valid for success. If the operation failed, the value of z is un-
-// defined but the returned value is nil.
+// must be valid for success. If the operation failed, the value of z is
+// undefined but the returned value is nil.
 func (z *Rat) SetString(s string) (*Rat, bool) {
 	if len(s) == 0 {
 		return nil, false
diff --git a/src/math/bits/example_test.go b/src/math/bits/example_test.go
index 5d30f4b259970..a43d1f365f600 100644
--- a/src/math/bits/example_test.go
+++ b/src/math/bits/example_test.go
@@ -36,3 +36,43 @@ func ExampleLeadingZeros64() {
 	// 64
 	// 63
 }
+
+func ExampleOnesCount() {
+	fmt.Printf("%b\n", 14)
+	fmt.Println(bits.OnesCount(14))
+	// Output:
+	// 1110
+	// 3
+}
+
+func ExampleOnesCount8() {
+	fmt.Printf("%b\n", 14)
+	fmt.Println(bits.OnesCount8(14))
+	// Output:
+	// 1110
+	// 3
+}
+
+func ExampleOnesCount16() {
+	fmt.Printf("%b\n", 14)
+	fmt.Println(bits.OnesCount16(14))
+	// Output:
+	// 1110
+	// 3
+}
+
+func ExampleOnesCount32() {
+	fmt.Printf("%b\n", 14)
+	fmt.Println(bits.OnesCount32(14))
+	// Output:
+	// 1110
+	// 3
+}
+
+func ExampleOnesCount64() {
+	fmt.Printf("%b\n", 14)
+	fmt.Println(bits.OnesCount64(14))
+	// Output:
+	// 1110
+	// 3
+}
diff --git a/src/plugin/plugin.go b/src/plugin/plugin.go
index 3dc79640487ee..c7744658122a2 100644
--- a/src/plugin/plugin.go
+++ b/src/plugin/plugin.go
@@ -4,8 +4,6 @@
 
 // Package plugin implements loading and symbol resolution of Go plugins.
 //
-// Currently plugins only work on Linux.
-//
 // A plugin is a Go main package with exported functions and variables that
 // has been built with:
 //
@@ -14,6 +12,9 @@
 // When a plugin is first opened, the init functions of all packages not
 // already part of the program are called. The main function is not run.
 // A plugin is only initialized once, and cannot be closed.
+//
+// The plugin support is currently incomplete, only supports Linux,
+// and has known bugs. Please report any issues.
 package plugin
 
 // Plugin is a loaded Go plugin.
diff --git a/src/reflect/deepequal.go b/src/reflect/deepequal.go
index f3fd7043e5ace..2fdd6a3d82ba3 100644
--- a/src/reflect/deepequal.go
+++ b/src/reflect/deepequal.go
@@ -178,6 +178,12 @@ func deepValueEqual(v1, v2 Value, visited map[visit]bool, depth int) bool {
 // DeepEqual has been defined so that the same short-cut applies
 // to slices and maps: if x and y are the same slice or the same map,
 // they are deeply equal regardless of content.
+//
+// As DeepEqual traverses the data values it may find a cycle. The
+// second and subsequent times that DeepEqual compares two pointer
+// values that have been compared before, it treats the values as
+// equal rather than examining the values to which they point.
+// This ensures that DeepEqual terminates.
 func DeepEqual(x, y interface{}) bool {
 	if x == nil || y == nil {
 		return x == y
diff --git a/src/runtime/cpuprof.go b/src/runtime/cpuprof.go
index c761e440b66fc..fb841a9f3ddcb 100644
--- a/src/runtime/cpuprof.go
+++ b/src/runtime/cpuprof.go
@@ -163,6 +163,15 @@ func (p *cpuProfile) addExtra() {
 	}
 }
 
+func (p *cpuProfile) addLostAtomic64(count uint64) {
+	hdr := [1]uint64{count}
+	lostStk := [2]uintptr{
+		funcPC(_LostSIGPROFDuringAtomic64) + sys.PCQuantum,
+		funcPC(_System) + sys.PCQuantum,
+	}
+	cpuprof.log.write(nil, 0, hdr[:], lostStk[:])
+}
+
 // CPUProfile panics.
 // It formerly provided raw access to chunks of
 // a pprof-format profile generated by the runtime.
diff --git a/src/runtime/hashmap_fast.go b/src/runtime/hashmap_fast.go
index 1f9b313219c52..67b978790989b 100644
--- a/src/runtime/hashmap_fast.go
+++ b/src/runtime/hashmap_fast.go
@@ -495,7 +495,7 @@ again:
 	}
 
 	// store new key/value at insert position
-	*((*uint32)(insertk)) = key
+	typedmemmove(t.key, insertk, unsafe.Pointer(&key))
 	*inserti = top
 	h.count++
 
@@ -583,7 +583,7 @@ again:
 	}
 
 	// store new key/value at insert position
-	*((*uint64)(insertk)) = key
+	typedmemmove(t.key, insertk, unsafe.Pointer(&key))
 	*inserti = top
 	h.count++
 
@@ -723,7 +723,7 @@ func mapdelete_fast32(t *maptype, h *hmap, key uint32) {
 			if key != *k {
 				continue
 			}
-			*k = 0
+			typedmemclr(t.key, unsafe.Pointer(k))
 			v := unsafe.Pointer(uintptr(unsafe.Pointer(b)) + dataOffset + bucketCnt*4 + i*uintptr(t.valuesize))
 			typedmemclr(t.elem, v)
 			b.tophash[i] = empty
@@ -778,7 +778,7 @@ func mapdelete_fast64(t *maptype, h *hmap, key uint64) {
 			if key != *k {
 				continue
 			}
-			*k = 0
+			typedmemclr(t.key, unsafe.Pointer(k))
 			v := unsafe.Pointer(uintptr(unsafe.Pointer(b)) + dataOffset + bucketCnt*8 + i*uintptr(t.valuesize))
 			typedmemclr(t.elem, v)
 			b.tophash[i] = empty
diff --git a/src/runtime/pprof/pprof_test.go b/src/runtime/pprof/pprof_test.go
index 22fea0a52f1ba..992d2abb6a335 100644
--- a/src/runtime/pprof/pprof_test.go
+++ b/src/runtime/pprof/pprof_test.go
@@ -12,6 +12,7 @@ import (
 	"fmt"
 	"internal/testenv"
 	"io"
+	"io/ioutil"
 	"math/big"
 	"os"
 	"os/exec"
@@ -20,6 +21,7 @@ import (
 	"runtime/pprof/internal/profile"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"testing"
 	"time"
 )
@@ -713,3 +715,32 @@ func TestCPUProfileLabel(t *testing.T) {
 		})
 	})
 }
+
+// Check that there is no deadlock when the program receives SIGPROF while in
+// 64bit atomics' critical section. Used to happen on mips{,le}. See #20146.
+func TestAtomicLoadStore64(t *testing.T) {
+	f, err := ioutil.TempFile("", "profatomic")
+	if err != nil {
+		t.Fatalf("TempFile: %v", err)
+	}
+	defer os.Remove(f.Name())
+	defer f.Close()
+
+	if err := StartCPUProfile(f); err != nil {
+		t.Fatal(err)
+	}
+	defer StopCPUProfile()
+
+	var flag uint64
+	done := make(chan bool, 1)
+
+	go func() {
+		for atomic.LoadUint64(&flag) == 0 {
+			runtime.Gosched()
+		}
+		done <- true
+	}()
+	time.Sleep(50 * time.Millisecond)
+	atomic.StoreUint64(&flag, 1)
+	<-done
+}
diff --git a/src/runtime/proc.go b/src/runtime/proc.go
index a5ada4f6db456..ed333bb92eeeb 100644
--- a/src/runtime/proc.go
+++ b/src/runtime/proc.go
@@ -3232,10 +3232,14 @@ var prof struct {
 	hz         int32
 }
 
-func _System()           { _System() }
-func _ExternalCode()     { _ExternalCode() }
-func _LostExternalCode() { _LostExternalCode() }
-func _GC()               { _GC() }
+func _System()                    { _System() }
+func _ExternalCode()              { _ExternalCode() }
+func _LostExternalCode()          { _LostExternalCode() }
+func _GC()                        { _GC() }
+func _LostSIGPROFDuringAtomic64() { _LostSIGPROFDuringAtomic64() }
+
+// Counts SIGPROFs received while in atomic64 critical section, on mips{,le}
+var lostAtomic64Count uint64
 
 // Called if we receive a SIGPROF signal.
 // Called by the signal handler, may run during STW.
@@ -3245,6 +3249,21 @@ func sigprof(pc, sp, lr uintptr, gp *g, mp *m) {
 		return
 	}
 
+	// On mips{,le}, 64bit atomics are emulated with spinlocks, in
+	// runtime/internal/atomic. If SIGPROF arrives while the program is inside
+	// the critical section, it creates a deadlock (when writing the sample).
+	// As a workaround, create a counter of SIGPROFs while in critical section
+	// to store the count, and pass it to sigprof.add() later when SIGPROF is
+	// received from somewhere else (with _LostSIGPROFDuringAtomic64 as pc).
+	if GOARCH == "mips" || GOARCH == "mipsle" {
+		if f := findfunc(pc); f.valid() {
+			if hasprefix(funcname(f), "runtime/internal/atomic") {
+				lostAtomic64Count++
+				return
+			}
+		}
+	}
+
 	// Profiling runs concurrently with GC, so it must not allocate.
 	// Set a trap in case the code does allocate.
 	// Note that on windows, one thread takes profiles of all the
@@ -3371,6 +3390,10 @@ func sigprof(pc, sp, lr uintptr, gp *g, mp *m) {
 	}
 
 	if prof.hz != 0 {
+		if (GOARCH == "mips" || GOARCH == "mipsle") && lostAtomic64Count > 0 {
+			cpuprof.addLostAtomic64(lostAtomic64Count)
+			lostAtomic64Count = 0
+		}
 		cpuprof.add(gp, stk[:n])
 	}
 	getg().m.mallocing--
diff --git a/src/runtime/symtab.go b/src/runtime/symtab.go
index 8e410c456099e..e1b41ca4ff8f0 100644
--- a/src/runtime/symtab.go
+++ b/src/runtime/symtab.go
@@ -409,6 +409,11 @@ var modulesSlice unsafe.Pointer // see activeModules
 //
 // A module is active once its gcdatamask and gcbssmask have been
 // assembled and it is usable by the GC.
+//
+// This is nosplit/nowritebarrier because it is called by the
+// cgo pointer checking code.
+//go:nosplit
+//go:nowritebarrier
 func activeModules() []*moduledata {
 	p := (*[]*moduledata)(atomic.Loadp(unsafe.Pointer(&modulesSlice)))
 	if p == nil {
diff --git a/src/testing/testing.go b/src/testing/testing.go
index 3d1c0c694741d..11af926c80f8e 100644
--- a/src/testing/testing.go
+++ b/src/testing/testing.go
@@ -970,7 +970,7 @@ func listTests(matchString func(pat, str string) (bool, error), tests []Internal
 		}
 	}
 	for _, example := range examples {
-		if ok, _ := matchString(*matchList, example.Name); ok && example.Output != "" {
+		if ok, _ := matchString(*matchList, example.Name); ok {
 			fmt.Println(example.Name)
 		}
 	}
diff --git a/src/time/zoneinfo_windows_test.go b/src/time/zoneinfo_windows_test.go
index 7ac1e8682238e..cf3b428c0956e 100644
--- a/src/time/zoneinfo_windows_test.go
+++ b/src/time/zoneinfo_windows_test.go
@@ -14,6 +14,14 @@ func testZoneAbbr(t *testing.T) {
 	t1 := Now()
 	// discard nsec
 	t1 = Date(t1.Year(), t1.Month(), t1.Day(), t1.Hour(), t1.Minute(), t1.Second(), 0, t1.Location())
+
+	// Skip the test if we're in a timezone with no abbreviation.
+	// Format will fallback to the numeric abbreviation, and
+	// Parse(RFC1123, ..) will fail (see Issue 21183).
+	if tz := t1.Format("MST"); tz[0] == '-' || tz[0] == '+' {
+		t.Skip("No zone abbreviation")
+	}
+
 	t2, err := Parse(RFC1123, t1.Format(RFC1123))
 	if err != nil {
 		t.Fatalf("Parse failed: %v", err)
diff --git a/test/README.md b/test/README.md
new file mode 100644
index 0000000000000..ca6a8c6580cfa
--- /dev/null
+++ b/test/README.md
@@ -0,0 +1,15 @@
+The test directory contains tests of the Go tool chain and runtime.
+It includes black box tests, regression tests, and error output tests.
+They are run as part of all.bash.
+
+To run just these tests, execute:
+
+    go run run.go
+
+Standard library tests should be written as regular Go tests in the appropriate package.
+
+The tool chain and runtime also have regular Go tests in their packages.
+The main reasons to add a new test to this directory are:
+
+* it is most naturally expressed using the test runner; or
+* it is also applicable to `gccgo` and other Go tool chains.