[dev.power64] all: merge default (dd5014ed9b01) into dev.power64

Still passes on amd64.

LGTM=austin
R=austin
CC=golang-codereviews
https://golang.org/cl/165110043

doc/asm.html

@@ -117,6 +117,9 @@ All user-defined symbols other than jump labels are written as offsets to these
 <p>
 The <code>SB</code> pseudo-register can be thought of as the origin of memory, so the symbol <code>foo(SB)</code>
 is the name <code>foo</code> as an address in memory.
+This form is used to name global functions and data.
+Adding <code>&lt;&gt;</code> to the name, as in <code>foo&lt;&gt;(SB)</code>, makes the name
+visible only in the current source file, like a top-level <code>static</code> declaration in a C file.
 </p>
 
 <p>
@@ -128,8 +131,11 @@ Thus <code>0(FP)</code> is the first argument to the function,
 When referring to a function argument this way, it is conventional to place the name
 at the beginning, as in <code>first_arg+0(FP)</code> and <code>second_arg+8(FP)</code>.
 Some of the assemblers enforce this convention, rejecting plain <code>0(FP)</code> and <code>8(FP)</code>.
-For assembly functions with Go prototypes, <code>go vet</code> will check that the argument names
+For assembly functions with Go prototypes, <code>go</code> <code>vet</code> will check that the argument names
 and offsets match.
+On 32-bit systems, the low and high 32 bits of a 64-bit value are distinguished by adding
+a <code>_lo</code> or <code>_hi</code> suffix to the name, as in <code>arg_lo+0(FP)</code> or <code>arg_hi+4(FP)</code>.
+If a Go prototype does not name its result, the expected assembly name is <code>ret</code>.
 </p>
 
 <p>
@@ -206,6 +212,8 @@ The frame size <code>$24-8</code> states that the function has a 24-byte frame
 and is called with 8 bytes of argument, which live on the caller's frame.
 If <code>NOSPLIT</code> is not specified for the <code>TEXT</code>,
 the argument size must be provided.
+For assembly functions with Go prototypes, <code>go</code> <code>vet</code> will check that the
+argument size is correct.
 </p>
 
 <p>
@@ -216,19 +224,20 @@ simple name <code>profileloop</code>.
 </p>
 
 <p>
-For <code>DATA</code> directives, the symbol is followed by a slash and the number
+Global data symbols are defined by a sequence of initializing
-of bytes the memory associated with the symbol occupies.
+<code>DATA</code> directives followed by a <code>GLOBL</code> directive.
-The arguments are optional flags and the data itself.
+Each <code>DATA</code> directive initializes a section of the
-For instance,
+corresponding memory.
-</p>
+The memory not explicitly initialized is zeroed.
+The general form of the <code>DATA</code> directive is
 
 <pre>
-DATA  runtime·isplan9(SB)/4, $1
+DATA	symbol+offset(SB)/width, value
 </pre>
 
 <p>
-declares the local symbol <code>runtime·isplan9</code> of size 4 and value 1.
+which initializes the symbol memory at the given offset and width with the given value.
-Again the symbol has the middle dot and is offset from <code>SB</code>.
+The <code>DATA</code> directives for a given symbol must be written with increasing offsets.
 </p>
 
 <p>
@@ -237,15 +246,26 @@ The arguments are optional flags and the size of the data being declared as a gl
 which will have initial value all zeros unless a <code>DATA</code> directive
 has initialized it.
 The <code>GLOBL</code> directive must follow any corresponding <code>DATA</code> directives.
-This example
+</p>
+
+<p>
+For example,
 </p>
 
 <pre>
-GLOBL runtime·tlsoffset(SB),$4
+DATA divtab&lt;&gt;+0x00(SB)/4, $0xf4f8fcff
+DATA divtab&lt;&gt;+0x04(SB)/4, $0xe6eaedf0
+...
+DATA divtab&lt;&gt;+0x3c(SB)/4, $0x81828384
+GLOBL divtab&lt;&gt;(SB), RODATA, $64
+
+GLOBL runtime·tlsoffset(SB), NOPTR, $4
 </pre>
 
 <p>
-declares <code>runtime·tlsoffset</code> to have size 4.
+declares and initializes <code>divtab&lt;&gt;</code>, a read-only 64-byte table of 4-byte integer values,
+and declares <code>runtime·tlsoffset</code>, a 4-byte, implicitly zeroed variable that
+contains no pointers.
 </p>
 
 <p>
@@ -299,6 +319,80 @@ This is a wrapper function and should not count as disabling <code>recover</code
 </li>
 </ul>
 
+<h3 id="runtime">Runtime Coordination</h3>
+
+<p>
+For garbage collection to run correctly, the runtime must know the
+location of pointers in all global data and in most stack frames.
+The Go compiler emits this information when compiling Go source files,
+but assembly programs must define it explicitly.
+</p>
+
+<p>
+A data symbol marked with the <code>NOPTR</code> flag (see above)
+is treated as containing no pointers to runtime-allocated data.
+A data symbol with the <code>RODATA</code> flag
+is allocated in read-only memory and is therefore treated
+as implicitly marked <code>NOPTR</code>.
+A data symbol with a total size smaller than a pointer
+is also treated as implicitly marked <code>NOPTR</code>.
+It is not possible to define a symbol containing pointers in an assembly source file;
+such a symbol must be defined in a Go source file instead.
+Assembly source can still refer to the symbol by name
+even without <code>DATA</code> and <code>GLOBL</code> directives.
+A good general rule of thumb is to define all non-<code>RODATA</code>
+symbols in Go instead of in assembly.
+</p>
+
+<p>
+Each function also needs annotations giving the location of
+live pointers in its arguments, results, and local stack frame.
+For an assembly function with no pointer results and
+either no local stack frame or no function calls,
+the only requirement is to define a Go prototype for the function
+in a Go source file in the same package.
+For more complex situations, explicit annotation is needed.
+These annotations use pseudo-instructions defined in the standard
+<code>#include</code> file <code>funcdata.h</code>.
+</p>
+
+<p>
+If a function has no arguments and no results,
+the pointer information can be omitted.
+This is indicated by an argument size annotation of <code>$<i>n</i>-0</code>
+on the <code>TEXT</code> instruction.
+Otherwise, pointer information must be provided by
+a Go prototype for the function in a Go source file,
+even for assembly functions not called directly from Go.
+(The prototype will also let <code>go</code> <code>vet</code> check the argument references.)
+At the start of the function, the arguments are assumed
+to be initialized but the results are assumed uninitialized.
+If the results will hold live pointers during a call instruction,
+the function should start by zeroing the results and then 
+executing the pseudo-instruction <code>GO_RESULTS_INITIALIZED</code>.
+This instruction records that the results are now initialized
+and should be scanned during stack movement and garbage collection.
+It is typically easier to arrange that assembly functions do not
+return pointers or do not contain call instructions;
+no assembly functions in the standard library use
+<code>GO_RESULTS_INITIALIZED</code>.
+</p>
+
+<p>
+If a function has no local stack frame,
+the pointer information can be omitted.
+This is indicated by a local frame size annotation of <code>$0-<i>n</i></code>
+on the <code>TEXT</code> instruction.
+The pointer information can also be omitted if the
+function contains no call instructions.
+Otherwise, the local stack frame must not contain pointers,
+and the assembly must confirm this fact by executing the 
+pseudo-instruction <code>NO_LOCAL_POINTERS</code>.
+Because stack resizing is implemented by moving the stack,
+the stack pointer may change during any function call:
+even pointers to stack data must not be kept in local variables.
+</p>
+
 <h2 id="architectures">Architecture-specific details</h2>
 
 <p>
@@ -434,13 +528,10 @@ Here's how the 386 runtime defines the 64-bit atomic load function.
 // so actually
 // void atomicload64(uint64 *res, uint64 volatile *addr);
 TEXT runtime·atomicload64(SB), NOSPLIT, $0-8
-	MOVL	4(SP), BX
+	MOVL	ptr+0(FP), AX
-	MOVL	8(SP), AX
+	LEAL	ret_lo+4(FP), BX
-	// MOVQ (%EAX), %MM0
+	BYTE $0x0f; BYTE $0x6f; BYTE $0x00	// MOVQ (%EAX), %MM0
-	BYTE $0x0f; BYTE $0x6f; BYTE $0x00
+	BYTE $0x0f; BYTE $0x7f; BYTE $0x03	// MOVQ %MM0, 0(%EBX)
-	// MOVQ %MM0, 0(%EBX)
+	BYTE $0x0F; BYTE $0x77			// EMMS
-	BYTE $0x0f; BYTE $0x7f; BYTE $0x03
-	// EMMS
-	BYTE $0x0F; BYTE $0x77
 	RET
 </pre>

doc/go1.4.html

@@ -0,0 +1,598 @@
+<!--{
+	"Title": "Go 1.4 Release Notes",
+	"Path":  "/doc/go1.4",
+	"Template": true
+}-->
+
+<h2 id="introduction">Introduction to Go 1.4</h2>
+
+<p>
+The latest Go release, version 1.4, arrives as scheduled six months after 1.3
+and contains only one tiny language change,
+a possibly breaking change to the compiler,
+a backwards-compatible simple form of <code>for</code>-<code>range</code> loop.
+The release focuses primarily on implementation work, improving the garbage collector
+and preparing the ground for a fully concurrent collector to be rolled out in the
+next few releases.
+Stacks are now contiguous, reallocated when necessary rather than linking on new
+"segments";
+this release therefore eliminates the notorious "hot stack split" problem.
+There are some new tools available including support in the <code>go</code> command
+for build-time source code generation
+and TODO.
+The release also adds support for ARM processors on Android and Native Client (NaCl)
+and AMD64 on Plan 9.
+As always, Go 1.4 keeps the <a href="/doc/go1compat.html">promise
+of compatibility</a>,
+and almost everything 
+will continue to compile and run without change when moved to 1.4.
+</p>
+
+<h2 id="language">Changes to the language</h2>
+
+<h3 id="forrange">For-range loops</h3>
+<p>
+Up until Go 1.3, <code>for</code>-<code>range</code> loop had two forms
+</p>
+
+<pre>
+for k, v := range x {
+	...
+}
+</pre>
+
+<p>
+and
+</p>
+
+<pre>
+for k := range x {
+	...
+}
+</pre>
+
+<p>
+If one was not interested in the loop values, only the iteration itself, it was still
+necessary to mention a variable (probably the <a href="/ref/spec#Blank_identifier">blank identifier</a>, as in
+<code>for</code> <code>_</code> <code>=</code> <code>range</code> <code>x</code>), because
+the form
+</p>
+
+<pre>
+for range x {
+	...
+}
+</pre>
+
+<p>
+was not syntactically permitted.
+</p>
+
+<p>
+This situation seemed awkward, so as of Go 1.4 the variable-free form is now legal.
+The pattern arises rarely but the code can be cleaner when it does.
+</p>
+
+<p>
+<em>Updating</em>: The change is strictly backwards compatible to existing Go
+programs, but tools that analyze Go parse trees may need to be modified to accept
+this new form as the
+<code>Key</code> field of <a href="/pkg/go/ast/#RangeStmt"><code>RangeStmt</code></a>
+may now be <code>nil</code>.
+</p>
+
+<h3 id="methodonpointertopointer">Method calls on **T</h3>
+
+<p>
+Given these declarations,
+</p>
+
+<pre>
+type T int
+func (T) M() {}
+var x **T
+</pre>
+
+<p>
+both <code>gc</code> and <code>gccgo</code> accepted the method call
+</p>
+
+<pre>
+x.M()
+</pre>
+
+<p>
+which is a double dereference of the pointer-to-pointer <code>x</code>.
+The Go specification allows a single dereference to be inserted automatically,
+but not two, so this call is erroneous according to the language definition.
+It has therefore been disallowed in Go 1.4, which is a breaking change,
+although very few programs will be affected.
+</p>
+
+<p>
+<em>Updating</em>: Code that depends on the old, erroneous behavior will no longer
+compile but is easy to fix by adding an explicit dereference.
+</p>
+
+<h2 id="os">Changes to the supported operating systems and architectures</h2>
+
+<h3 id="android">Android</h3>
+
+<p>
+Go 1.4 can build binaries for ARM processors running the Android operating system.
+It can also build a <code>.so</code> library that can be loaded by an Android application
+using the supporting packages in the <a href="http://code.google.com/p/go.mobile">go.mobile</a> repository.
+A brief description of the plans for this experimental port are available
+<a href="/s/go14android">here</a>.
+</p>
+
+<h3 id="naclarm">NaCl on ARM</h3>
+
+<p>
+The previous release introduced Native Client (NaCl) support for the 32-bit x86
+(<code>GOARCH=386</code>)
+and 64-bit x86 using 32-bit pointers (GOARCH=amd64p32).
+The 1.4 release adds NaCl support for ARM (GOARCH=arm).
+</p>
+
+<h3 id="plan9amd64">Plan9 on AMD64</h3>
+
+<p>
+This release adds support for the Plan 9 operating system on AMD64 processors,
+provided the kernel supports the <code>nsec</code> system call and uses 4K pages.
+</p>
+
+<h2 id="compatibility">Changes to the compatibility guidelines</h2>
+
+<p>
+The <a href="/pkg/unsafe/"><code>unsafe</code></a> package allows one
+to defeat Go's type system by exploiting internal details of the implementation
+or machine representation of data.
+It was never explicitly specified what use of <code>unsafe</code> meant
+with respect to compatibility as specified in the
+<a href="go1compat.html">Go compatibility guidelines</a>.
+The answer, of course, is that we can make no promise of compatibility
+for code that does unsafe things.
+</p>
+
+<p>
+We have clarified this situation in the documentation included in the release.
+The <a href="go1compat.html">Go compatibility guidelines</a> and the
+docs for the <a href="/pkg/unsafe/"><code>unsafe</code></a> package
+are now explicit that unsafe code is not guaranteed to remain compatible.
+</p>
+  
+<p>
+<em>Updating</em>: Nothing technical has changed; this is just a clarification
+of the documentation.
+</p>
+
+
+<h2 id="impl">Changes to the implementations and tools</h2>
+
+<h3 id="runtime">Changes to the runtime</h3>
+
+<p>
+Up to Go 1.4, the runtime (garbage collector, concurrency support, interface management,
+maps, slices, strings, ...) was mostly written in C, with some assembler support.
+In 1.4, much of the code has been translated to Go so that the garbage collector can scan
+the stacks of programs in the runtime and get accurate information about what variables
+are active.
+This change was large but should have no semantic effect on programs.
+</p>
+
+<p>
+This rewrite allows the garbage collector in 1.4 to be fully precise,
+meaning that it is aware of the location of all active pointers in the program.
+This means the heap will be smaller as there will be no false positives keeping non-pointers alive.
+Other related changes also reduce the heap size, which is smaller by 10%-30% overall
+relative to the previous release.
+</p>
+
+<p>
+A consequence is that stacks are no longer segmented, eliminating the "hot split" problem.
+When a stack limit is reached, a new, larger stack is allocated, all active frames for
+the goroutine are copied there, and any pointers into the stack are updated.
+Performance can be noticeably better in some cases and is always more predictable.
+Details are available in <a href="/s/contigstacks">the design document</a>.
+</p>
+
+<p>
+The use of contiguous stacks means that stacks can start smaller without triggering performance issues,
+so the default starting size for a goroutine's stack in 1.4 has been reduced to 2048 bytes from 8192 bytes.
+TODO: It may be bumped to 4096 for the release.
+</p>
+
+<p>
+As preparation for the concurrent garbage collector scheduled for the 1.5 release,
+writes to pointer values in the heap are now done by a function call,
+called a write barrier, rather than directly from the function updating the value.
+In this next release, this will permit the garbage collector to mediate writes to the heap while it is running.
+This change has no semantic effect on programs in 1.4, but was
+included in the release to test the compiler and the resulting performance.
+</p>
+
+<p>
+The implementation of interface values has been modified.
+In earlier releases, the interface contained a word that was either a pointer or a one-word
+scalar value, depending on the type of the concrete object stored.
+This implementation was problematical for the garbage collector,
+so as of 1.4 interface values always hold a pointer.
+In running programs, most interface values were pointers anyway,
+so the effect is minimal, but programs that store integers (for example) in
+interfaces will see more allocations.
+</p>
+
+<p>
+As of Go 1.3, the runtime crashes if it finds a memory word that should contain
+a valid pointer but instead contains an obviously invalid pointer (for example, the value 3).
+Programs that store integers in pointer values may run afoul of this check and crash.
+In Go 1.4, setting the <a href="/pkg/runtime/"><code>GODEBUG</code></a> variable
+<code>invalidptr=0</code> disables
+the crash as a workaround, but we cannot guarantee that future releases will be
+able to avoid the crash; the correct fix is to rewrite code not to alias integers and pointers.
+</p>
+
+<h3 id="asm">Assembly</h3>
+
+<p>
+The language accepted by the assemblers <code>cmd/5a</code>, <code>cmd/6a</code>
+and <code>cmd/8a</code> has had several changes,
+mostly to make it easier to deliver type information to the runtime.
+</p>
+
+<p>
+First, the <code>textflag.h</code> file that defines flags for <code>TEXT</code> directives
+has been copied from the linker source directory to a standard location so it can be
+included with the simple directive
+</p>
+
+<pre>
+#include "textflag.h"
+</pre>
+
+<p>
+The more important changes are in how assembler source can define the necessary
+type information.
+For most programs it will suffice to move data
+definitions (<code>DATA</code> and <code>GLOBL</code> directives)
+out of assembly into Go files
+and to write a Go declaration for each assembly function.
+The <a href="/doc/asm#runtime">assembly document</a> describes what to do.
+</p>
+
+<p>
+<em>Updating</em>:
+Assembly files that include <code>textflag.h</code> from its old
+location will still work, but should be updated.
+For the type information, most assembly routines will need no change,
+but all should be examined.
+Assembly source files that define data,
+functions with non-empty stack frames, or functions that return pointers
+need particular attention.
+A description of the necessary (but simple) changes
+is in the <a href="/doc/asm#runtime">assembly document</a>.
+</p>
+
+<p>
+More information about these changes is in the <a href="/doc/asm">assembly document</a>.
+</p>
+
+<h3 id="gccgo">Status of gccgo</h3>
+
+<p>
+TODO gccgo news
+</p>
+
+<h3 id="internalpackages">Internal packages</h3>
+
+<p>
+Go's package system makes it easy to structure programs into components with clean boundaries,
+but there are only two forms of access: local (unexported) and global (exported).
+Sometimes one wishes to have components that are not exported,
+for instance to avoid acquiring clients of interfaces to code that is part of a public repository
+but not intended for use outside the program to which it belongs.
+</p>
+
+<p>
+The Go language does not have the power to enforce this distinction, but as of Go 1.4 the
+<a href="/cmd/go/"><code>go</code></a> command introduces
+a mechanism to define "internal" packages that may not be imported by packages outside
+the source subtree in which they reside.
+</p>
+
+<p>
+To create such a package, place it in a directory named <code>internal</code> or in a subdirectory of a directory
+named internal.
+When the <code>go</code> command sees an import of a package with <code>internal</code> in its path,
+it verifies that the package doing the import
+is within the tree rooted at the parent of the <code>internal</code> directory.
+For example, a package <code>.../a/b/c/internal/d/e/f</code>
+can be imported only by code in the directory tree rooted at <code>.../a/b/c</code>.
+It cannot be imported by code in <code>.../a/b/g</code> or in any other repository.
+</p>
+
+<p>
+For Go 1.4, the internal package mechanism is enforced for the main Go repository;
+from 1.5 and onward it will be enforced for any repository.
+</p>
+
+<p>
+Full details of the mechanism are in
+<a href="http://golang.org/s/go14internal">the design document</a>.
+</p>
+
+<h3 id="canonicalimports">Canonical import paths</h3>
+
+<p>
+Code often lives in repositories hosted by public services such as <code>github.com</code>,
+meaning that the import paths for packages begin with the name of the hosting service,
+<code>github.com/rsc/pdf</code> for example.
+One can use
+<a href="/cmd/go/#hdr-Remote_import_paths">an existing mechanism</a>
+to provide a "custom" or "vanity" import path such as
+<code>rsc.io/pdf</code>, but
+that creates two valid import paths for the package.
+That is a problem: one may inadvertently import the package through the two
+distinct paths in a single program, which is wasteful;
+miss an update to a package because the path being used is not recognized to be
+out of date;
+or break clients using the old path by moving the package to a different hosting service.
+</p>
+
+<p>
+Go 1.4 introduces an annotation for package clauses in Go source that identify a canonical
+import path for the package.
+If an import is attempted using a path that is not canonical,
+the <a href="/cmd/go/"><code>go</code></a> command
+will refuse to compile the importing package.
+</p>
+
+<p>
+The syntax is simple: put an identifying comment on the package line.
+For our example, the package clause would read:
+</p>
+
+<pre>
+package pdf // import "rsc.io/pdf"
+</pre>
+
+<p>
+With this in place,
+the <code>go</code> command will
+refuse to compile a package that imports <code>github.com/rsc/pdf</code>, 
+ensuring that the code can be moved without breaking users.
+</p>
+
+<p>
+The check is at build time, not download time, so if <code>go</code> <code>get</code>
+fails because of this check, the mis-imported package has been copied to the local machine
+and should be removed manually.
+</p>
+
+<p>
+Further information is in
+<a href="http://golang.org/s/go14customimport">the design document</a>.
+</p>
+
+<h3 id="gogenerate">The go generate subcommand</h3>
+
+<p>
+The <a href="/cmd/go/"><code>go</code></a> command has a new subcommand,
+<a href="/cmd/go/#hdr-Generate_Go_files_by_processing_source"><code>go generate</code></a>,
+to automate the running of tools to generate source code before compilation.
+For example, it can be used to run the <a href="/cmd/yacc"><code>yacc</code></a>
+compiler-compiler on a <code>.y</code> file to produce the Go source file implementing the grammar,
+or to automate the generation of <code>String</code> methods for typed constants using the new
+<a href="http://godoc.org/code.google.com/p/go.tools/cmd/stringer">stringer</a>
+tool in the <code>go.tools</code> repository.
+</p>
+
+<p>
+For more information, see the 
+<a href="http://golang.org/s/go1.4-generate">design document</a>.
+</p>
+
+<h3 id="filenames">Change to file name handling</h3>
+
+<p>
+Build constraints, also known as build tags, control compilation by including or excluding files
+(see the documentation <a href="/pkg/go/build/"><code>/go/build</code></a>).
+Compilation can also be controlled by the name of the file itself by "tagging" the file with
+a suffix (before the <code>.go</code> or <code>.s</code> extension) with an underscore
+and the name of the architecture or operating system.
+For instance, the file <code>gopher_arm.go</code> will only be compiled if the target
+processor is an ARM.
+</p>
+
+<p>
+Before Go 1.4, a file called just <code>arm.go</code> was similarly tagged, but this behavior
+can break sources when new architectures are added, causing files to suddenly become tagged.
+In 1.4, therefore, a file will be tagged in this manner only if the tag (architecture or operating
+system name) is preceded by an underscore.
+</p>
+
+<p>
+<em>Updating</em>: Packages that depend on the old behavior will no longer compile correctly.
+Files with names like <code>windows.go</code> or <code>amd64.go</code> should either
+have explicit build tags added to the source or be renamed to something like
+<code>os_windows.go</code> or <code>support_amd64.go</code>.
+</p>
+
+<h3 id="gocmd">Other changes to the go command</h3>
+
+<p>
+There were a number of minor changes to the
+<a href="/cmd/go/"><code>cmd/go</code></a>
+command worth noting.
+</p>
+
+<ul>
+
+<li>
+Unless <a href="/cmd/cgo/"><code>cgo</code></a> is being used to build the package,
+the <code>go</code> command now refuses to compile C source files,
+since the relevant C compilers
+(<a href="/cmd/6c/"><code>6c</code></a> etc.)
+are intended to be removed from the installation in some future release.
+(They are used today only to build part of the runtime.)
+It is difficult to use them correctly in any case, so any extant uses are likely incorrect,
+so we have disabled them.
+</li>
+
+<li>
+The <a href="/cmd/go/#hdr-Test_packages"><code>go</code> <code>test</code></a>
+subcommand has a new flag, <code>-o</code>, to set the name of the resulting binary,
+corresponding to the same flag in other subcommands.
+The non-functional <code>-file</code> flag has been removed.
+</li>
+
+<li>
+The <a href="/cmd/go/#hdr-Test_packages"><code>go</code> <code>test</code></a>
+subcommand will compile and link all <code>*_test.go</code> files in the package,
+even when there are no <code>Test</code> functions in them. 
+It previously ignored such files.
+</li>
+
+<li>
+The behavior of the
+<a href="/cmd/go/#hdr-Test_packages"><code>go</code> <code>build</code></a>
+subcommand's
+<code>-a</code> flag has been changed for non-development installations.
+For installations running a released distribution, the <code>-a</code> flag will no longer
+rebuild the standard library and commands, to avoid overwriting the installation's files.
+</li>
+
+</ul>
+
+<h3 id="godoc">Changes to godoc</h3>
+<p>
+TODO godoc news
+</p>
+
+<h3 id="pkg">Changes to package source layout</h3>
+
+<p>
+In the main Go source repository, the source code for the packages was kept in
+the directory <code>src/pkg</code>, which made sense but differed from
+other repositories, including the Go sub-repositories such as <code>go.tools</code>.
+In Go 1.4, the<code> pkg</code> level of the source tree is now gone, so for example
+the <a href="/pkg/fmt/"><code>fmt</code></a> package's source, once kept in
+directory <code>src/pkg/fmt</code>, now lives one level higher in <code>src/fmt</code>.
+</p>
+
+<p>
+<em>Updating</em>: Tools like <code>godoc</code> that discover source code
+need to know about the new location. All tools and services maintained by the Go team
+have been updated.
+</p>
+
+<h3 id="misc">Miscellany</h3>
+
+<p>
+The standard repository's top-level <code>misc</code> directory used to contain
+Go support for editors and IDEs: plugins, initialization scripts and so on.
+Maintaining these was becoming time-consuming
+and needed external help because many of the editors listed were not used by
+members of the core team.
+It also required us to make decisions about which plugin was best for a given
+editor, even for editors we do not use.
+</p>
+
+<p>
+The Go community at large is much better suited to managing this information.
+In Go 1.4, therefore, this support has been removed from the repository.
+Instead, there is a curated, informative list of what's available on
+a <a href="https://code.google.com/p/go-wiki/wiki/IDEsAndTextEditorPlugins">wiki page</a>.
+</p>
+
+<h2 id="performance">Performance</h2>
+
+<p>
+Most programs will run about the same speed or slightly faster in 1.4 than in 1.3;
+some will be slightly slower.
+There are many changes, making it hard to be precise about what to expect.
+</p>
+
+<p>
+As mentioned above, much of the runtime was translated to Go from C,
+which led to some reduction in heap sizes.
+It also improved performance slightly because the Go compiler is better
+at optimization, due to things like inlining, than the C compiler used to build
+the runtime.
+</p>
+
+<p>
+The garbage collector was sped up, leading to measurable improvements for
+garbage-heavy programs.
+On the other hand, the new write barriers slow things down again, typically
+by about the same amount but, depending on their behavior, some programs
+may be somewhat slower or faster.
+</p>
+
+<p>
+Library changes that affect performance are documented below.
+</p>
+
+<h2 id="library">Changes to the standard library</h2>
+
+<h3 id="new_packages">New packages</h3>
+
+<p>
+There are no new packages in this release.
+</p>
+
+<h3 id="major_library_changes">Major changes to the library</h3>
+
+<p>
+TODO major changes
+</p>
+
+<pre>
+encoding/gob: remove unsafe (CL 102680045)
+syscall: now frozen (CL 129820043); go.sys subrepo created: http://golang.org/s/go1.4-syscall
+</pre>
+
+<h3 id="minor_library_changes">Minor changes to the library</h3>
+
+<p>
+The following list summarizes a number of minor changes to the library, mostly additions.
+See the relevant package documentation for more information about each change.
+</p>
+
+<ul>
+
+<li> TODO changes
+</li>
+</ul>
+
+<pre>
+
+cmd/6l, liblink: use pc-relative addressing for all memory references, so that linking Go binaries at high addresses works (CL 125140043). This cuts the maximum size of a Go binary's text+data+bss from 4GB to 2GB.
+
+bufio: handling of empty tokens at EOF changed, may require scanner change (CL 145390043)
+compress/flate, compress/gzip, compress/zlib: Reset support (https://codereview.appspot.com/97140043)
+crypto/tls: add support for ALPN (RFC 7301) (CL 108710046)
+crypto/tls: support programmatic selection of server certificates (CL 107400043)
+encoding/asn1: optional elements with a default value will now only be omitted if they have that value (CL 86960045)
+fmt: print type *map[T]T as &amp;map[k:v] (CL 154870043)
+encoding/csv: do not quote empty strings, quote \. (CL 164760043)
+net/http: add Request.BasicAuth method (CL 76540043)
+net/http: add Transport.DialTLS hook (CL 137940043)
+net/http/httputil: add ReverseProxy.ErrorLog (CL 132750043)
+os: implement symlink support for windows (CL 86160044)
+reflect: add type.Comparable (CL 144020043)
+reflect: Value is one word smaller
+runtime: implement monotonic clocks on windows (CL 108700045)
+runtime: MemStats.Mallocs now counts very small allocations missed in Go 1.3. This may break tests using runtime.ReadMemStats or testing.AllocsPerRun by giving a more accurate answer than Go 1.3 did (CL 143150043).
+runtime/race: freebsd is supported (CL 107270043)
+runtime: add PauseEnd array to MemStats and GCStats (CL 153670043)
+swig: Due to runtime changes Go 1.4 will require SWIG 3.0.3 (not yet released)
+sync/atomic: add Value (CL 136710045)
+syscall: Setuid, Setgid are disabled on linux platforms. On linux those syscalls operate on the calling thread, not the whole process. This does not match the semantics of other platforms, nor the expectations of the caller, so the operations have been disabled until issue 1435 is resolved (CL 106170043)
+testing: add Coverage (CL 98150043)
+testing: add TestMain support (CL 148770043)
+text/scanner: add IsIdentRune field of Scanner. (CL 108030044)
+text/template: allow comparison of signed and unsigned integers (CL 149780043)
+time: use the micro symbol (µ (U+00B5)) to print microsecond duration (CL 105030046)
+</pre>

doc/go1.4.txt

@@ -1,53 +0,0 @@
-This file collects notes about what has changed since Go 1.3
-and should be mentioned in the Go 1.4 release notes.
-
-Please keep the descriptions to a single line, starting with the
-package or cmd/xxx directory name, and ending in a CL number.
-Please keep the list sorted (as in sort.Strings of the lines).
-
-spec: permit for range x (CL 104680043)
-
-the directory src/pkg has been deleted, for instance src/pkg/fmt is now just src/fmt (CL 134570043)
-
-cmd/6l, liblink: use pc-relative addressing for all memory references, so that linking Go binaries at high addresses works (CL 125140043). This cuts the maximum size of a Go binary's text+data+bss from 4GB to 2GB.
-cmd/go: import comments (CL 124940043)
-cmd/go: implement "internal" (CL 120600043)
-cmd/go: implement "generate" (CL 125580044)
-cmd/go: disallow C sources except when using cgo (CL 149720043)
-cmd/go: add test -o flag (CL 149070043)
-cmd/go: redefine build -a to skip standard library in releases (CL 151730045)
-cmd/go: compile and link all _test.go files during 'go test', even in packages where there are no Test functions (CL 150980043)
-cmd/go: (via go/build): a GOOS prefix acts as a tag only if preceded by an underscore. this is a breaking change. (CL 147690043)
-
-asm: make textflag.h available outside of cmd/ld (CL 128050043)
-bufio: handling of empty tokens at EOF changed, may require scanner change (CL 145390043)
-compress/flate, compress/gzip, compress/zlib: Reset support (https://codereview.appspot.com/97140043)
-crypto/tls: add support for ALPN (RFC 7301) (CL 108710046)
-crypto/tls: support programmatic selection of server certificates (CL 107400043)
-encoding/asn1: optional elements with a default value will now only be omitted if they have that value (CL 86960045)
-flag: it is now an error to set a flag multiple times (CL 156390043)
-fmt: print type *map[T]T as &map[k:v] (CL 154870043)
-encoding/csv: do not quote empty strings, quote \. (CL 164760043)
-encoding/gob: remove unsafe (CL 102680045)
-misc: deleted editor support; refer to https://code.google.com/p/go-wiki/wiki/IDEsAndTextEditorPlugins instead (CL 105470043)
-net/http: add Request.BasicAuth method (CL 76540043)
-net/http: add Transport.DialTLS hook (CL 137940043)
-net/http/httputil: add ReverseProxy.ErrorLog (CL 132750043)
-os: implement symlink support for windows (CL 86160044)
-reflect: add type.Comparable (CL 144020043)
-runtime: implement monotonic clocks on windows (CL 108700045)
-runtime: memory consumption is reduced by 10-30% (CL 106260045 removes type info from heap, CL 145790043 reduces stack size to 2K (4K on plan 9 and windows))
-runtime: MemStats.Mallocs now counts very small allocations missed in Go 1.3. This may break tests using runtime.ReadMemStats or testing.AllocsPerRun by giving a more accurate answer than Go 1.3 did (CL 143150043).
-runtime/race: freebsd is supported (CL 107270043)
-swig: Due to runtime changes Go 1.4 will require SWIG 3.0.3 (not yet released)
-sync/atomic: add Value (CL 136710045)
-syscall: Setuid, Setgid are disabled on linux platforms. On linux those syscalls operate on the calling thread, not the whole process. This does not match the semantics of other platforms, nor the expectations of the caller, so the operations have been disabled until issue 1435 is resolved (CL 106170043)
-syscall: now frozen (CL 129820043)
-testing: add Coverage (CL 98150043)
-testing: add TestMain support (CL 148770043)
-text/scanner: add IsIdentRune field of Scanner. (CL 108030044)
-text/template: allow comparison of signed and unsigned integers (CL 149780043)
-time: use the micro symbol (µ (U+00B5)) to print microsecond duration (CL 105030046)
-unsafe: document the existing situation that unsafe programs are not go1-guaranteed (CL 162060043)
-
-go.sys subrepo created: http://golang.org/s/go1.4-syscall

doc/go_mem.html

@@ -21,6 +21,29 @@ reads of a variable in one goroutine can be guaranteed to
 observe values produced by writes to the same variable in a different goroutine.
 </p>
 
+
+<h2>Advice</h2>
+
+<p>
+Programs that modify data being simultaneously accessed by multiple goroutines
+must serialize such access.
+</p>
+
+<p>
+To serialize access, protect the data with channel operations or other synchronization primitives
+such as those in the <a href="/pkg/sync/"><code>sync</code></a>
+and <a href="/pkg/sync/atomic/"><code>sync/atomic</code></a> packages.
+</p>
+
+<p>
+If you must read the rest of this document to understand the behavior of your program,
+you are being too clever.
+</p>
+
+<p>
+Don't be clever.
+</p>
+
 <h2>Happens Before</h2>
 
 <p>

doc/go_spec.html

@@ -1,6 +1,6 @@
 <!--{
 	"Title": "The Go Programming Language Specification",
-	"Subtitle": "Version of October 23, 2014",
+	"Subtitle": "Version of October 27, 2014",
 	"Path": "/ref/spec"
 }-->
 
@@ -2449,12 +2449,11 @@ Primary expressions are the operands for unary and binary expressions.
 PrimaryExpr =
 	Operand |
 	Conversion |
-	BuiltinCall |
 	PrimaryExpr Selector |
 	PrimaryExpr Index |
 	PrimaryExpr Slice |
 	PrimaryExpr TypeAssertion |
-	PrimaryExpr Call .
+	PrimaryExpr Arguments .
 
 Selector       = "." identifier .
 Index          = "[" Expression "]" .
@@ -2462,8 +2461,7 @@ Slice          = "[" ( [ Expression ] ":" [ Expression ] ) |
                      ( [ Expression ] ":" Expression ":" Expression )
                  "]" .
 TypeAssertion  = "." "(" Type ")" .
-Call           = "(" [ ArgumentList [ "," ] ] ")" .
+Arguments      = "(" [ ( ExpressionList | Type [ "," ExpressionList ] ) [ "..." ] [ "," ] ] ")" .
-ArgumentList   = ExpressionList [ "..." ] .
 </pre>
 
 
@@ -3166,7 +3164,7 @@ the method.
 <pre>
 math.Atan2(x, y)  // function call
 var pt *Point
-pt.Scale(3.5)  // method call with receiver pt
+pt.Scale(3.5)     // method call with receiver pt
 </pre>
 
 <p>
@@ -5371,11 +5369,6 @@ so they can only appear in <a href="#Calls">call expressions</a>;
 they cannot be used as function values.
 </p>
 
-<pre class="ebnf">
-BuiltinCall = identifier "(" [ BuiltinArgs [ "," ] ] ")" .
-BuiltinArgs = Type [ "," ArgumentList ] | ArgumentList .
-</pre>
-
 <h3 id="Close">Close</h3>
 
 <p>

src/cmd/gc/builtin.c

@@ -24,7 +24,6 @@ char *runtimeimport =
 	"func @\"\".printslice (? any)\n"
 	"func @\"\".printnl ()\n"
 	"func @\"\".printsp ()\n"
-	"func @\"\".goprintf ()\n"
 	"func @\"\".concatstring2 (? string, ? string) (? string)\n"
 	"func @\"\".concatstring3 (? string, ? string, ? string) (? string)\n"
 	"func @\"\".concatstring4 (? string, ? string, ? string, ? string) (? string)\n"

src/cmd/gc/runtime.go

@@ -36,7 +36,6 @@ func printeface(any)
 func printslice(any)
 func printnl()
 func printsp()
-func goprintf()
 
 func concatstring2(string, string) string
 func concatstring3(string, string, string) string

src/cmd/gc/walk.c

@@ -7,7 +7,7 @@
 #include	"go.h"
 #include	"../ld/textflag.h"
 
-static	Node*	walkprint(Node*, NodeList**, int);
+static	Node*	walkprint(Node*, NodeList**);
 static	Node*	writebarrierfn(char*, Type*, Type*);
 static	Node*	applywritebarrier(Node*, NodeList**);
 static	Node*	mapfn(char*, Type*);
@@ -32,6 +32,7 @@ static	void	walkmul(Node**, NodeList**);
 static	void	walkdiv(Node**, NodeList**);
 static	int	bounded(Node*, int64);
 static	Mpint	mpzero;
+static	void	walkprintfunc(Node**, NodeList**);
 
 void
 walk(Node *fn)
@@ -226,8 +227,7 @@ walkstmt(Node **np)
 		switch(n->left->op) {
 		case OPRINT:
 		case OPRINTN:
-			walkexprlist(n->left->list, &n->ninit);
+			walkprintfunc(&n->left, &n->ninit);
-			n->left = walkprint(n->left, &n->ninit, 1);
 			break;
 		case OCOPY:
 			n->left = copyany(n->left, &n->ninit, 1);
@@ -260,8 +260,7 @@ walkstmt(Node **np)
 		switch(n->left->op) {
 		case OPRINT:
 		case OPRINTN:
-			walkexprlist(n->left->list, &n->ninit);
+			walkprintfunc(&n->left, &n->ninit);
-			n->left = walkprint(n->left, &n->ninit, 1);
 			break;
 		case OCOPY:
 			n->left = copyany(n->left, &n->ninit, 1);
@@ -543,7 +542,7 @@ walkexpr(Node **np, NodeList **init)
 	case OPRINT:
 	case OPRINTN:
 		walkexprlist(n->list, init);
-		n = walkprint(n, init, 0);
+		n = walkprint(n, init);
 		goto ret;
 
 	case OPANIC:
@@ -1757,7 +1756,7 @@ ret:
 
 // generate code for print
 static Node*
-walkprint(Node *nn, NodeList **init, int defer)
+walkprint(Node *nn, NodeList **init)
 {
 	Node *r;
 	Node *n;
@@ -1765,31 +1764,17 @@ walkprint(Node *nn, NodeList **init, int defer)
 	Node *on;
 	Type *t;
 	int notfirst, et, op;
-	NodeList *calls, *intypes, *args;
+	NodeList *calls;
-	Fmt fmt;
 
 	on = nil;
 	op = nn->op;
 	all = nn->list;
 	calls = nil;
 	notfirst = 0;
-	intypes = nil;
-	args = nil;
-
-	memset(&fmt, 0, sizeof fmt);
-	if(defer) {
-		// defer print turns into defer printf with format string
-		fmtstrinit(&fmt);
-		intypes = list(intypes, nod(ODCLFIELD, N, typenod(types[TSTRING])));
-		args = list1(nod(OXXX, N, N));
-	}
 
 	for(l=all; l; l=l->next) {
 		if(notfirst) {
-			if(defer)
+			calls = list(calls, mkcall("printsp", T, init));
-				fmtprint(&fmt, " ");
-			else
-				calls = list(calls, mkcall("printsp", T, init));
 		}
 		notfirst = op == OPRINTN;
 
@@ -1817,122 +1802,63 @@ walkprint(Node *nn, NodeList **init, int defer)
 		t = n->type;
 		et = n->type->etype;
 		if(isinter(n->type)) {
-			if(defer) {
+			if(isnilinter(n->type))
-				if(isnilinter(n->type))
+				on = syslook("printeface", 1);
-					fmtprint(&fmt, "%%e");
+			else
-				else
+				on = syslook("printiface", 1);
-					fmtprint(&fmt, "%%i");
+			argtype(on, n->type);		// any-1
-			} else {
-				if(isnilinter(n->type))
-					on = syslook("printeface", 1);
-				else
-					on = syslook("printiface", 1);
-				argtype(on, n->type);		// any-1
-			}
 		} else if(isptr[et] || et == TCHAN || et == TMAP || et == TFUNC || et == TUNSAFEPTR) {
-			if(defer) {
+			on = syslook("printpointer", 1);
-				fmtprint(&fmt, "%%p");
+			argtype(on, n->type);	// any-1
-			} else {
-				on = syslook("printpointer", 1);
-				argtype(on, n->type);	// any-1
-			}
 		} else if(isslice(n->type)) {
-			if(defer) {
+			on = syslook("printslice", 1);
-				fmtprint(&fmt, "%%a");
+			argtype(on, n->type);	// any-1
-			} else {
-				on = syslook("printslice", 1);
-				argtype(on, n->type);	// any-1
-			}
 		} else if(isint[et]) {
-			if(defer) {
+			if(et == TUINT64) {
-				if(et == TUINT64)
+				if((t->sym->pkg == runtimepkg || compiling_runtime) && strcmp(t->sym->name, "hex") == 0)
-					fmtprint(&fmt, "%%U");
+					on = syslook("printhex", 0);
-				else {
+				else
-					fmtprint(&fmt, "%%D");
+					on = syslook("printuint", 0);
-					t = types[TINT64];
+			} else
-				}
+				on = syslook("printint", 0);
-			} else {
-				if(et == TUINT64) {
-					if((t->sym->pkg == runtimepkg || compiling_runtime) && strcmp(t->sym->name, "hex") == 0)
-						on = syslook("printhex", 0);
-					else
-						on = syslook("printuint", 0);
-				} else
-					on = syslook("printint", 0);
-			}
 		} else if(isfloat[et]) {
-			if(defer) {
+			on = syslook("printfloat", 0);
-				fmtprint(&fmt, "%%f");
-				t = types[TFLOAT64];
-			} else
-				on = syslook("printfloat", 0);
 		} else if(iscomplex[et]) {
-			if(defer) {
+			on = syslook("printcomplex", 0);
-				fmtprint(&fmt, "%%C");
-				t = types[TCOMPLEX128];
-			} else
-				on = syslook("printcomplex", 0);
 		} else if(et == TBOOL) {
-			if(defer)
+			on = syslook("printbool", 0);
-				fmtprint(&fmt, "%%t");
-			else
-				on = syslook("printbool", 0);
 		} else if(et == TSTRING) {
-			if(defer)
+			on = syslook("printstring", 0);
-				fmtprint(&fmt, "%%S");
-			else
-				on = syslook("printstring", 0);
 		} else {
 			badtype(OPRINT, n->type, T);
 			continue;
 		}
 
-		if(!defer) {
+		t = *getinarg(on->type);
-			t = *getinarg(on->type);
+		if(t != nil)
-			if(t != nil)
+			t = t->type;
-				t = t->type;
+		if(t != nil)
-			if(t != nil)
+			t = t->type;
-				t = t->type;
-		}
 
 		if(!eqtype(t, n->type)) {
 			n = nod(OCONV, n, N);
 			n->type = t;
 		}
 
-		if(defer) {
-			intypes = list(intypes, nod(ODCLFIELD, N, typenod(t)));
-			args = list(args, n);
-		} else {
-			r = nod(OCALL, on, N);
-			r->list = list1(n);
-			calls = list(calls, r);
-		}
-	}
-
-	if(defer) {
-		if(op == OPRINTN)
-			fmtprint(&fmt, "\n");
-		on = syslook("goprintf", 1);
-		on->type = functype(nil, intypes, nil);
-		args->n = nod(OLITERAL, N, N);
-		args->n->val.ctype = CTSTR;
-		args->n->val.u.sval = strlit(fmtstrflush(&fmt));
 		r = nod(OCALL, on, N);
-		r->list = args;
+		r->list = list1(n);
-		typecheck(&r, Etop);
+		calls = list(calls, r);
-		walkexpr(&r, init);
-	} else {
-		if(op == OPRINTN)
-			calls = list(calls, mkcall("printnl", T, nil));
-		typechecklist(calls, Etop);
-		walkexprlist(calls, init);
-
-		r = nod(OEMPTY, N, N);
-		typecheck(&r, Etop);
-		walkexpr(&r, init);
-		r->ninit = calls;
 	}
+
+	if(op == OPRINTN)
+		calls = list(calls, mkcall("printnl", T, nil));
+	typechecklist(calls, Etop);
+	walkexprlist(calls, init);
+
+	r = nod(OEMPTY, N, N);
+	typecheck(&r, Etop);
+	walkexpr(&r, init);
+	r->ninit = calls;
 	return r;
 }
 
@@ -3229,7 +3155,7 @@ countfield(Type *t)
 static void
 walkcompare(Node **np, NodeList **init)
 {
-	Node *n, *l, *r, *call, *a, *li, *ri, *expr;
+	Node *n, *l, *r, *call, *a, *li, *ri, *expr, *cmpl, *cmpr;
 	int andor, i;
 	Type *t, *t1;
 	
@@ -3249,18 +3175,25 @@ walkcompare(Node **np, NodeList **init)
 		break;
 	}
 	
-	if(!islvalue(n->left) || !islvalue(n->right)) {
+	cmpl = n->left;
-		fatal("arguments of comparison must be lvalues");
+	while(cmpl != N && cmpl->op == OCONVNOP)
+		cmpl = cmpl->left;
+	cmpr = n->right;
+	while(cmpr != N && cmpr->op == OCONVNOP)
+		cmpr = cmpr->left;
+	
+	if(!islvalue(cmpl) || !islvalue(cmpr)) {
+		fatal("arguments of comparison must be lvalues - %N %N", cmpl, cmpr);
 	}
 
 	l = temp(ptrto(t));
-	a = nod(OAS, l, nod(OADDR, n->left, N));
+	a = nod(OAS, l, nod(OADDR, cmpl, N));
 	a->right->etype = 1;  // addr does not escape
 	typecheck(&a, Etop);
 	*init = list(*init, a);
 
 	r = temp(ptrto(t));
-	a = nod(OAS, r, nod(OADDR, n->right, N));
+	a = nod(OAS, r, nod(OADDR, cmpr, N));
 	a->right->etype = 1;  // addr does not escape
 	typecheck(&a, Etop);
 	*init = list(*init, a);
@@ -3941,3 +3874,71 @@ candiscard(Node *n)
 	
 	return 1;
 }
+
+// rewrite
+//	print(x, y, z)
+// into
+//	func(a1, a2, a3) {
+//		print(a1, a2, a3)
+//	}(x, y, z)
+// and same for println.
+static void
+walkprintfunc(Node **np, NodeList **init)
+{
+	Node *n;
+	Node *a, *fn, *t, *oldfn;
+	NodeList *l, *printargs;
+	int num;
+	char buf[100];
+	static int prgen;
+	
+	n = *np;
+
+	if(n->ninit != nil) {
+		walkstmtlist(n->ninit);
+		*init = concat(*init, n->ninit);
+		n->ninit = nil;
+	}
+
+	t = nod(OTFUNC, N, N);
+	num = 0;
+	printargs = nil;
+	for(l=n->list; l != nil; l=l->next) {
+		snprint(buf, sizeof buf, "a%d", num++);
+		a = nod(ODCLFIELD, newname(lookup(buf)), typenod(l->n->type));
+		t->list = list(t->list, a);
+		printargs = list(printargs, a->left);
+	}
+
+	fn = nod(ODCLFUNC, N, N);
+	snprint(buf, sizeof buf, "print·%d", ++prgen);
+	fn->nname = newname(lookup(buf));
+	fn->nname->defn = fn;
+	fn->nname->ntype = t;
+	declare(fn->nname, PFUNC);
+
+	oldfn = curfn;
+	curfn = nil;
+	funchdr(fn);
+	
+	a = nod(n->op, N, N);
+	a->list = printargs;
+	typecheck(&a, Etop);
+	walkstmt(&a);
+	
+	fn->nbody = list1(a);
+
+	funcbody(fn);
+	
+	typecheck(&fn, Etop);
+	typechecklist(fn->nbody, Etop);
+	xtop = list(xtop, fn);
+	curfn = oldfn;
+
+	a = nod(OCALL, N, N);
+	a->left = fn->nname;
+	a->list = n->list;
+	typecheck(&a, Etop);
+	walkexpr(&a, init);
+	*np = a;
+}

src/cmd/go/get.go

@@ -16,7 +16,7 @@ import (
 )
 
 var cmdGet = &Command{
-	UsageLine: "get [-d] [-fix] [-t] [-u] [build flags] [packages]",
+	UsageLine: "get [-d] [-f] [-fix] [-t] [-u] [build flags] [packages]",
 	Short:     "download and install packages and dependencies",
 	Long: `
 Get downloads and installs the packages named by the import paths,
@@ -25,6 +25,11 @@ along with their dependencies.
 The -d flag instructs get to stop after downloading the packages; that is,
 it instructs get not to install the packages.
 
+The -f flag, valid only when -u is set, forces get -u not to verify that
+each package has been checked out from the source control repository
+implied by its import path. This can be useful if the source is a local fork
+of the original.
+
 The -fix flag instructs get to run the fix tool on the downloaded packages
 before resolving dependencies or building the code.
 
@@ -53,6 +58,7 @@ See also: go build, go install, go clean.
 }
 
 var getD = cmdGet.Flag.Bool("d", false, "")
+var getF = cmdGet.Flag.Bool("f", false, "")
 var getT = cmdGet.Flag.Bool("t", false, "")
 var getU = cmdGet.Flag.Bool("u", false, "")
 var getFix = cmdGet.Flag.Bool("fix", false, "")
@@ -63,6 +69,10 @@ func init() {
 }
 
 func runGet(cmd *Command, args []string) {
+	if *getF && !*getU {
+		fatalf("go get: cannot use -f flag without -u")
+	}
+
 	// Phase 1.  Download/update.
 	var stk importStack
 	for _, arg := range downloadPaths(args) {
@@ -268,7 +278,7 @@ func downloadPackage(p *Package) error {
 		repo = "<local>" // should be unused; make distinctive
 
 		// Double-check where it came from.
-		if *getU && vcs.remoteRepo != nil {
+		if *getU && vcs.remoteRepo != nil && !*getF {
 			dir := filepath.Join(p.build.SrcRoot, rootPath)
 			if remote, err := vcs.remoteRepo(vcs, dir); err == nil {
 				if rr, err := repoRootForImportPath(p.ImportPath); err == nil {

src/cmd/go/test.bash

@@ -219,6 +219,16 @@ q' | ed $d/src/$config >/dev/null 2>&1
 			cat $d/err
 			ok=false
 		fi
+		
+		if GOPATH=$d ./testgo get -d -f -u $url 2>$d/err; then
+			echo "go get -d -u $url succeeded with wrong remote repo"
+			cat $d/err
+			ok=false
+		elif ! egrep -i 'validating server certificate|not found' $d/err >/dev/null; then
+			echo "go get -d -f -u $url failed for wrong reason"
+			cat $d/err
+			ok=false
+		fi
 	fi
 	rm -rf $d
 }

src/cmd/objdump/main.go

@@ -159,7 +159,7 @@ func dump(tab *gosym.Table, lookup lookupFunc, disasm disasmFunc, goarch string,
 
 	printed := false
 	for _, sym := range syms {
-		if sym.Code != 'T' || sym.Size == 0 || sym.Name == "_text" || sym.Name == "text" || sym.Addr < textStart || symRE != nil && !symRE.MatchString(sym.Name) {
+		if (sym.Code != 'T' && sym.Code != 't') || sym.Size == 0 || sym.Name == "_text" || sym.Name == "text" || sym.Addr < textStart || symRE != nil && !symRE.MatchString(sym.Name) {
 			continue
 		}
 		if sym.Addr >= textStart+uint64(len(textData)) || sym.Addr+uint64(sym.Size) > textStart+uint64(len(textData)) {

src/cmd/objdump/objdump_test.go

@@ -157,12 +157,15 @@ var armNeed = []string{
 // binary for the current system (only) and test that objdump
 // can handle that one.
 
-func TestDisasm(t *testing.T) {
+func testDisasm(t *testing.T, flags ...string) {
 	tmp, exe := buildObjdump(t)
 	defer os.RemoveAll(tmp)
 
 	hello := filepath.Join(tmp, "hello.exe")
-	out, err := exec.Command("go", "build", "-o", hello, "testdata/fmthello.go").CombinedOutput()
+	args := []string{"build", "-o", hello}
+	args = append(args, flags...)
+	args = append(args, "testdata/fmthello.go")
+	out, err := exec.Command("go", args...).CombinedOutput()
 	if err != nil {
 		t.Fatalf("go build fmthello.go: %v\n%s", err, out)
 	}
@@ -194,3 +197,15 @@ func TestDisasm(t *testing.T) {
 		t.Logf("full disassembly:\n%s", text)
 	}
 }
+
+func TestDisasm(t *testing.T) {
+	testDisasm(t)
+}
+
+func TestDisasmExtld(t *testing.T) {
+	switch runtime.GOOS {
+	case "plan9", "windows":
+		t.Skipf("skipping on %s", runtime.GOOS)
+	}
+	testDisasm(t, "-ldflags=-linkmode=external")
+}

src/encoding/json/encode.go

@@ -805,6 +805,9 @@ func (e *encodeState) string(s string) (int, error) {
 			case '\r':
 				e.WriteByte('\\')
 				e.WriteByte('r')
+			case '\t':
+				e.WriteByte('\\')
+				e.WriteByte('t')
 			default:
 				// This encodes bytes < 0x20 except for \n and \r,
 				// as well as <, > and &. The latter are escaped because they
@@ -878,9 +881,12 @@ func (e *encodeState) stringBytes(s []byte) (int, error) {
 			case '\r':
 				e.WriteByte('\\')
 				e.WriteByte('r')
+			case '\t':
+				e.WriteByte('\\')
+				e.WriteByte('t')
 			default:
 				// This encodes bytes < 0x20 except for \n and \r,
-				// as well as < and >. The latter are escaped because they
+				// as well as <, >, and &. The latter are escaped because they
 				// can lead to security holes when user-controlled strings
 				// are rendered into JSON and served to some browsers.
 				e.WriteString(`\u00`)

src/encoding/json/encode_test.go

@@ -478,3 +478,55 @@ func TestEncodePointerString(t *testing.T) {
 		t.Fatalf("*N = %d; want 42", *back.N)
 	}
 }
+
+var encodeStringTests = []struct {
+	in  string
+	out string
+}{
+	{"\x00", `"\u0000"`},
+	{"\x01", `"\u0001"`},
+	{"\x02", `"\u0002"`},
+	{"\x03", `"\u0003"`},
+	{"\x04", `"\u0004"`},
+	{"\x05", `"\u0005"`},
+	{"\x06", `"\u0006"`},
+	{"\x07", `"\u0007"`},
+	{"\x08", `"\u0008"`},
+	{"\x09", `"\t"`},
+	{"\x0a", `"\n"`},
+	{"\x0b", `"\u000b"`},
+	{"\x0c", `"\u000c"`},
+	{"\x0d", `"\r"`},
+	{"\x0e", `"\u000e"`},
+	{"\x0f", `"\u000f"`},
+	{"\x10", `"\u0010"`},
+	{"\x11", `"\u0011"`},
+	{"\x12", `"\u0012"`},
+	{"\x13", `"\u0013"`},
+	{"\x14", `"\u0014"`},
+	{"\x15", `"\u0015"`},
+	{"\x16", `"\u0016"`},
+	{"\x17", `"\u0017"`},
+	{"\x18", `"\u0018"`},
+	{"\x19", `"\u0019"`},
+	{"\x1a", `"\u001a"`},
+	{"\x1b", `"\u001b"`},
+	{"\x1c", `"\u001c"`},
+	{"\x1d", `"\u001d"`},
+	{"\x1e", `"\u001e"`},
+	{"\x1f", `"\u001f"`},
+}
+
+func TestEncodeString(t *testing.T) {
+	for _, tt := range encodeStringTests {
+		b, err := Marshal(tt.in)
+		if err != nil {
+			t.Errorf("Marshal(%q): %v", tt.in, err)
+			continue
+		}
+		out := string(b)
+		if out != tt.out {
+			t.Errorf("Marshal(%q) = %#q, want %#q", tt.in, out, tt.out)
+		}
+	}
+}

src/fmt/doc.go

@@ -38,8 +38,8 @@
 		%E	scientific notation, e.g. -1234.456E+78
 		%f	decimal point but no exponent, e.g. 123.456
 		%F	synonym for %f
-		%g	whichever of %e or %f produces more compact output
+		%g	%e for large exponents, %f otherwise
-		%G	whichever of %E or %f produces more compact output
+		%G	%E for large exponents, %F otherwise
 	String and slice of bytes:
 		%s	the uninterpreted bytes of the string or slice
 		%q	a double-quoted string safely escaped with Go syntax

src/html/template/js_test.go

@@ -138,7 +138,7 @@ func TestJSValEscaper(t *testing.T) {
 		// Newlines.
 		{"\r\n\u2028\u2029", `"\r\n\u2028\u2029"`},
 		// "\v" == "v" on IE 6 so use "\x0b" instead.
-		{"\t\x0b", `"\u0009\u000b"`},
+		{"\t\x0b", `"\t\u000b"`},
 		{struct{ X, Y int }{1, 2}, `{"X":1,"Y":2}`},
 		{[]interface{}{}, "[]"},
 		{[]interface{}{42, "foo", nil}, `[42,"foo",null]`},

src/net/z_last_test.go

@@ -8,6 +8,7 @@ import (
 	"flag"
 	"fmt"
 	"testing"
+	"time"
 )
 
 var testDNSFlood = flag.Bool("dnsflood", false, "whether to test dns query flooding")
@@ -35,3 +36,64 @@ func TestDNSThreadLimit(t *testing.T) {
 
 	// If we're still here, it worked.
 }
+
+func TestLookupIPDeadline(t *testing.T) {
+	if !*testDNSFlood {
+		t.Skip("test disabled; use -dnsflood to enable")
+	}
+
+	const N = 5000
+	const timeout = 3 * time.Second
+	c := make(chan error, 2*N)
+	for i := 0; i < N; i++ {
+		name := fmt.Sprintf("%d.net-test.golang.org", i)
+		go func() {
+			_, err := lookupIPDeadline(name, time.Now().Add(timeout/2))
+			c <- err
+		}()
+		go func() {
+			_, err := lookupIPDeadline(name, time.Now().Add(timeout))
+			c <- err
+		}()
+	}
+	qstats := struct {
+		succeeded, failed         int
+		timeout, temporary, other int
+		unknown                   int
+	}{}
+	deadline := time.After(timeout + time.Second)
+	for i := 0; i < 2*N; i++ {
+		select {
+		case <-deadline:
+			t.Fatal("deadline exceeded")
+		case err := <-c:
+			switch err := err.(type) {
+			case nil:
+				qstats.succeeded++
+			case Error:
+				qstats.failed++
+				if err.Timeout() {
+					qstats.timeout++
+				}
+				if err.Temporary() {
+					qstats.temporary++
+				}
+				if !err.Timeout() && !err.Temporary() {
+					qstats.other++
+				}
+			default:
+				qstats.failed++
+				qstats.unknown++
+			}
+		}
+	}
+
+	// A high volume of DNS queries for sub-domain of golang.org
+	// would be coordinated by authoritative or recursive server,
+	// or stub resolver which implements query-response rate
+	// limitation, so we can expect some query successes and more
+	// failures including timeout, temporary and other here.
+	// As a rule, unknown must not be shown but it might possibly
+	// happen due to issue 4856 for now.
+	t.Logf("%v succeeded, %v failed (%v timeout, %v temporary, %v other, %v unknown)", qstats.succeeded, qstats.failed, qstats.timeout, qstats.temporary, qstats.other, qstats.unknown)
+}

src/os/dir_unix.go

@@ -36,7 +36,7 @@ func (f *File) readdirnames(n int) (names []string, err error) {
 		if d.bufp >= d.nbuf {
 			d.bufp = 0
 			var errno error
-			d.nbuf, errno = syscall.ReadDirent(f.fd, d.buf)
+			d.nbuf, errno = fixCount(syscall.ReadDirent(f.fd, d.buf))
 			if errno != nil {
 				return names, NewSyscallError("readdirent", errno)
 			}

src/os/file.go

@@ -255,3 +255,12 @@ var lstat = Lstat
 func Rename(oldpath, newpath string) error {
 	return rename(oldpath, newpath)
 }
+
+// Many functions in package syscall return a count of -1 instead of 0.
+// Using fixCount(call()) instead of call() corrects the count.
+func fixCount(n int, err error) (int, error) {
+	if n < 0 {
+		n = 0
+	}
+	return n, err
+}

src/os/file_plan9.go

@@ -244,14 +244,14 @@ func (f *File) Sync() (err error) {
 // read reads up to len(b) bytes from the File.
 // It returns the number of bytes read and an error, if any.
 func (f *File) read(b []byte) (n int, err error) {
-	return syscall.Read(f.fd, b)
+	return fixCount(syscall.Read(f.fd, b))
 }
 
 // pread reads len(b) bytes from the File starting at byte offset off.
 // It returns the number of bytes read and the error, if any.
 // EOF is signaled by a zero count with err set to nil.
 func (f *File) pread(b []byte, off int64) (n int, err error) {
-	return syscall.Pread(f.fd, b, off)
+	return fixCount(syscall.Pread(f.fd, b, off))
 }
 
 // write writes len(b) bytes to the File.
@@ -262,7 +262,7 @@ func (f *File) write(b []byte) (n int, err error) {
 	if len(b) == 0 {
 		return 0, nil
 	}
-	return syscall.Write(f.fd, b)
+	return fixCount(syscall.Write(f.fd, b))
 }
 
 // pwrite writes len(b) bytes to the File starting at byte offset off.
@@ -273,7 +273,7 @@ func (f *File) pwrite(b []byte, off int64) (n int, err error) {
 	if len(b) == 0 {
 		return 0, nil
 	}
-	return syscall.Pwrite(f.fd, b, off)
+	return fixCount(syscall.Pwrite(f.fd, b, off))
 }
 
 // seek sets the offset for the next Read or Write on file to offset, interpreted

src/os/file_posix.go

@@ -18,7 +18,7 @@ func sigpipe() // implemented in package runtime
 func Readlink(name string) (string, error) {
 	for len := 128; ; len *= 2 {
 		b := make([]byte, len)
-		n, e := syscall.Readlink(name, b)
+		n, e := fixCount(syscall.Readlink(name, b))
 		if e != nil {
 			return "", &PathError{"readlink", name, e}
 		}

src/os/file_unix.go

@@ -187,7 +187,7 @@ func (f *File) read(b []byte) (n int, err error) {
 	if needsMaxRW && len(b) > maxRW {
 		b = b[:maxRW]
 	}
-	return syscall.Read(f.fd, b)
+	return fixCount(syscall.Read(f.fd, b))
 }
 
 // pread reads len(b) bytes from the File starting at byte offset off.
@@ -197,7 +197,7 @@ func (f *File) pread(b []byte, off int64) (n int, err error) {
 	if needsMaxRW && len(b) > maxRW {
 		b = b[:maxRW]
 	}
-	return syscall.Pread(f.fd, b, off)
+	return fixCount(syscall.Pread(f.fd, b, off))
 }
 
 // write writes len(b) bytes to the File.
@@ -208,7 +208,7 @@ func (f *File) write(b []byte) (n int, err error) {
 		if needsMaxRW && len(bcap) > maxRW {
 			bcap = bcap[:maxRW]
 		}
-		m, err := syscall.Write(f.fd, bcap)
+		m, err := fixCount(syscall.Write(f.fd, bcap))
 		n += m
 
 		// If the syscall wrote some data but not all (short write)
@@ -234,7 +234,7 @@ func (f *File) pwrite(b []byte, off int64) (n int, err error) {
 	if needsMaxRW && len(b) > maxRW {
 		b = b[:maxRW]
 	}
-	return syscall.Pwrite(f.fd, b, off)
+	return fixCount(syscall.Pwrite(f.fd, b, off))
 }
 
 // seek sets the offset for the next Read or Write on file to offset, interpreted

src/os/file_windows.go

@@ -295,7 +295,7 @@ func (f *File) read(b []byte) (n int, err error) {
 	if f.isConsole {
 		return f.readConsole(b)
 	}
-	return syscall.Read(f.fd, b)
+	return fixCount(syscall.Read(f.fd, b))
 }
 
 // pread reads len(b) bytes from the File starting at byte offset off.
@@ -376,7 +376,7 @@ func (f *File) write(b []byte) (n int, err error) {
 	if f.isConsole {
 		return f.writeConsole(b)
 	}
-	return syscall.Write(f.fd, b)
+	return fixCount(syscall.Write(f.fd, b))
 }
 
 // pwrite writes len(b) bytes to the File starting at byte offset off.

src/runtime/asm_386.s

@@ -732,6 +732,20 @@ needm:
 	MOVL	g(CX), BP
 	MOVL	g_m(BP), BP
 
+	// Set m->sched.sp = SP, so that if a panic happens
+	// during the function we are about to execute, it will
+	// have a valid SP to run on the g0 stack.
+	// The next few lines (after the havem label)
+	// will save this SP onto the stack and then write
+	// the same SP back to m->sched.sp. That seems redundant,
+	// but if an unrecovered panic happens, unwindm will
+	// restore the g->sched.sp from the stack location
+	// and then onM will try to use it. If we don't set it here,
+	// that restored SP will be uninitialized (typically 0) and
+	// will not be usable.
+	MOVL	m_g0(BP), SI
+	MOVL	SP, (g_sched+gobuf_sp)(SI)
+
 havem:
 	// Now there's a valid m, and we're running on its m->g0.
 	// Save current m->g0->sched.sp on stack and then set it to SP.

src/runtime/asm_amd64.s

@@ -717,6 +717,20 @@ needm:
 	get_tls(CX)
 	MOVQ	g(CX), BP
 	MOVQ	g_m(BP), BP
+	
+	// Set m->sched.sp = SP, so that if a panic happens
+	// during the function we are about to execute, it will
+	// have a valid SP to run on the g0 stack.
+	// The next few lines (after the havem label)
+	// will save this SP onto the stack and then write
+	// the same SP back to m->sched.sp. That seems redundant,
+	// but if an unrecovered panic happens, unwindm will
+	// restore the g->sched.sp from the stack location
+	// and then onM will try to use it. If we don't set it here,
+	// that restored SP will be uninitialized (typically 0) and
+	// will not be usable.
+	MOVQ	m_g0(BP), SI
+	MOVQ	SP, (g_sched+gobuf_sp)(SI)
 
 havem:
 	// Now there's a valid m, and we're running on its m->g0.

src/runtime/asm_arm.s

@@ -556,6 +556,21 @@ TEXT	·cgocallback_gofunc(SB),NOSPLIT,$8-12
 	MOVW	$runtime·needm(SB), R0
 	BL	(R0)
 
+	// Set m->sched.sp = SP, so that if a panic happens
+	// during the function we are about to execute, it will
+	// have a valid SP to run on the g0 stack.
+	// The next few lines (after the havem label)
+	// will save this SP onto the stack and then write
+	// the same SP back to m->sched.sp. That seems redundant,
+	// but if an unrecovered panic happens, unwindm will
+	// restore the g->sched.sp from the stack location
+	// and then onM will try to use it. If we don't set it here,
+	// that restored SP will be uninitialized (typically 0) and
+	// will not be usable.
+	MOVW	g_m(g), R8
+	MOVW	m_g0(R8), R3
+	MOVW	R13, (g_sched+gobuf_sp)(R3)
+
 havem:
 	MOVW	g_m(g), R8
 	MOVW	R8, savedm-4(SP)

src/runtime/crash_cgo_test.go

@@ -8,6 +8,7 @@ package runtime_test
 
 import (
 	"runtime"
+	"strings"
 	"testing"
 )
 
@@ -34,6 +35,17 @@ func TestCgoTraceback(t *testing.T) {
 	}
 }
 
+func TestCgoExternalThreadPanic(t *testing.T) {
+	if runtime.GOOS == "windows" || runtime.GOOS == "plan9" {
+		t.Skipf("no pthreads on %s", runtime.GOOS)
+	}
+	got := executeTest(t, cgoExternalThreadPanicSource, nil, "main.c", cgoExternalThreadPanicC)
+	want := "panic: BOOM"
+	if !strings.Contains(got, want) {
+		t.Fatalf("want failure containing %q. output:\n%s\n", want, got)
+	}
+}
+
 const cgoSignalDeadlockSource = `
 package main
 
@@ -117,3 +129,43 @@ func main() {
 	fmt.Printf("OK\n")
 }
 `
+
+const cgoExternalThreadPanicSource = `
+package main
+
+// void start(void);
+import "C"
+
+func main() {
+	C.start()
+	select {}
+}
+
+//export gopanic
+func gopanic() {
+	panic("BOOM")
+}
+`
+
+const cgoExternalThreadPanicC = `
+#include <stdlib.h>
+#include <stdio.h>
+#include <pthread.h>
+
+void gopanic(void);
+
+static void*
+die(void* x)
+{
+	gopanic();
+	return 0;
+}
+
+void
+start(void)
+{
+	pthread_t t;
+	if(pthread_create(&t, 0, die, 0) != 0)
+		printf("pthread_create failed\n");
+}
+`

src/runtime/crash_test.go

@@ -31,7 +31,7 @@ func testEnv(cmd *exec.Cmd) *exec.Cmd {
 	return cmd
 }
 
-func executeTest(t *testing.T, templ string, data interface{}) string {
+func executeTest(t *testing.T, templ string, data interface{}, extra ...string) string {
 	switch runtime.GOOS {
 	case "android", "nacl":
 		t.Skipf("skipping on %s", runtime.GOOS)
@@ -61,7 +61,20 @@ func executeTest(t *testing.T, templ string, data interface{}) string {
 		t.Fatalf("failed to close file: %v", err)
 	}
 
-	got, _ := testEnv(exec.Command("go", "run", src)).CombinedOutput()
+	for i := 0; i < len(extra); i += 2 {
+		if err := ioutil.WriteFile(filepath.Join(dir, extra[i]), []byte(extra[i+1]), 0666); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	cmd := exec.Command("go", "build", "-o", "a.exe")
+	cmd.Dir = dir
+	out, err := testEnv(cmd).CombinedOutput()
+	if err != nil {
+		t.Fatalf("building source: %v\n%s", err, out)
+	}
+
+	got, _ := testEnv(exec.Command(filepath.Join(dir, "a.exe"))).CombinedOutput()
 	return string(got)
 }
 

src/runtime/debug/garbage.go

@@ -16,6 +16,7 @@ type GCStats struct {
 	NumGC          int64           // number of garbage collections
 	PauseTotal     time.Duration   // total pause for all collections
 	Pause          []time.Duration // pause history, most recent first
+	PauseEnd       []time.Time     // pause end times history, most recent first
 	PauseQuantiles []time.Duration
 }
 
@@ -30,25 +31,36 @@ type GCStats struct {
 func ReadGCStats(stats *GCStats) {
 	// Create a buffer with space for at least two copies of the
 	// pause history tracked by the runtime. One will be returned
-	// to the caller and the other will be used as a temporary buffer
+	// to the caller and the other will be used as transfer buffer
-	// for computing quantiles.
+	// for end times history and as a temporary buffer for
+	// computing quantiles.
 	const maxPause = len(((*runtime.MemStats)(nil)).PauseNs)
-	if cap(stats.Pause) < 2*maxPause {
+	if cap(stats.Pause) < 2*maxPause+3 {
-		stats.Pause = make([]time.Duration, 2*maxPause)
+		stats.Pause = make([]time.Duration, 2*maxPause+3)
 	}
 
-	// readGCStats fills in the pause history (up to maxPause entries)
+	// readGCStats fills in the pause and end times histories (up to
-	// and then three more: Unix ns time of last GC, number of GC,
+	// maxPause entries) and then three more: Unix ns time of last GC,
-	// and total pause time in nanoseconds. Here we depend on the
+	// number of GC, and total pause time in nanoseconds. Here we
-	// fact that time.Duration's native unit is nanoseconds, so the
+	// depend on the fact that time.Duration's native unit is
-	// pauses and the total pause time do not need any conversion.
+	// nanoseconds, so the pauses and the total pause time do not need
+	// any conversion.
 	readGCStats(&stats.Pause)
 	n := len(stats.Pause) - 3
 	stats.LastGC = time.Unix(0, int64(stats.Pause[n]))
 	stats.NumGC = int64(stats.Pause[n+1])
 	stats.PauseTotal = stats.Pause[n+2]
+	n /= 2 // buffer holds pauses and end times
 	stats.Pause = stats.Pause[:n]
 
+	if cap(stats.PauseEnd) < maxPause {
+		stats.PauseEnd = make([]time.Time, 0, maxPause)
+	}
+	stats.PauseEnd = stats.PauseEnd[:0]
+	for _, ns := range stats.Pause[n : n+n] {
+		stats.PauseEnd = append(stats.PauseEnd, time.Unix(0, int64(ns)))
+	}
+
 	if len(stats.PauseQuantiles) > 0 {
 		if n == 0 {
 			for i := range stats.PauseQuantiles {

src/runtime/debug/garbage_test.go

@@ -70,6 +70,19 @@ func TestReadGCStats(t *testing.T) {
 			t.Errorf("stats.PauseQuantiles[%d]=%d > stats.PauseQuantiles[%d]=%d", i, q[i], i+1, q[i+1])
 		}
 	}
+
+	// compare memory stats with gc stats:
+	if len(stats.PauseEnd) != n {
+		t.Fatalf("len(stats.PauseEnd) = %d, want %d", len(stats.PauseEnd), n)
+	}
+	off := (int(mstats.NumGC) + len(mstats.PauseEnd) - 1) % len(mstats.PauseEnd)
+	for i := 0; i < n; i++ {
+		dt := stats.PauseEnd[i]
+		if dt.UnixNano() != int64(mstats.PauseEnd[off]) {
+			t.Errorf("stats.PauseEnd[%d] = %d, want %d", i, dt, mstats.PauseEnd[off])
+		}
+		off = (off + len(mstats.PauseEnd) - 1) % len(mstats.PauseEnd)
+	}
 }
 
 var big = make([]byte, 1<<20)

src/runtime/extern.go

@@ -39,6 +39,12 @@ a comma-separated list of name=val pairs. Supported names are:
 	gcdead: setting gcdead=1 causes the garbage collector to clobber all stack slots
 	that it thinks are dead.
 
+	invalidptr: defaults to invalidptr=1, causing the garbage collector and stack
+	copier to crash the program if an invalid pointer value (for example, 1)
+	is found in a pointer-typed location. Setting invalidptr=0 disables this check.
+	This should only be used as a temporary workaround to diagnose buggy code.
+	The real fix is to not store integers in pointer-typed locations.
+
 	scheddetail: setting schedtrace=X and scheddetail=1 causes the scheduler to emit
 	detailed multiline info every X milliseconds, describing state of the scheduler,
 	processors, threads and goroutines.

src/runtime/funcdata.h

@@ -28,6 +28,9 @@
 // defines the pointer map for the function's arguments.
 // GO_ARGS should be the first instruction in a function that uses it.
 // It can be omitted if there are no arguments at all.
+// GO_ARGS is inserted implicitly by the linker for any function
+// that also has a Go prototype and therefore is usually not necessary
+// to write explicitly.
 #define GO_ARGS	FUNCDATA $FUNCDATA_ArgsPointerMaps, go_args_stackmap(SB)
 
 // GO_RESULTS_INITIALIZED indicates that the assembly function

src/runtime/malloc.h

@@ -267,7 +267,8 @@ struct MStats
 	uint64	next_gc;	// next GC (in heap_alloc time)
 	uint64  last_gc;	// last GC (in absolute time)
 	uint64	pause_total_ns;
-	uint64	pause_ns[256];
+	uint64	pause_ns[256];  // circular buffer of recent GC pause lengths
+	uint64	pause_end[256]; // circular buffer of recent GC end times (nanoseconds since 1970)
 	uint32	numgc;
 	bool	enablegc;
 	bool	debuggc;

src/runtime/mem.go

@@ -44,7 +44,8 @@ type MemStats struct {
 	NextGC       uint64 // next collection will happen when HeapAlloc ≥ this amount
 	LastGC       uint64 // end time of last collection (nanoseconds since 1970)
 	PauseTotalNs uint64
-	PauseNs      [256]uint64 // circular buffer of recent GC pause times, most recent at [(NumGC+255)%256]
+	PauseNs      [256]uint64 // circular buffer of recent GC pause durations, most recent at [(NumGC+255)%256]
+	PauseEnd     [256]uint64 // circular buffer of recent GC pause end times
 	NumGC        uint32
 	EnableGC     bool
 	DebugGC      bool

src/runtime/mgc0.c

@@ -330,7 +330,7 @@ scanblock(byte *b, uintptr n, byte *ptrmask)
 			if(obj == nil)
 				continue;
 			if(obj < arena_start || obj >= arena_used) {
-				if((uintptr)obj < PhysPageSize) {
+				if((uintptr)obj < PhysPageSize && runtime·invalidptr) {
 					s = nil;
 					goto badobj;
 				}
@@ -375,7 +375,7 @@ scanblock(byte *b, uintptr n, byte *ptrmask)
 					else
 						runtime·printf(" span=%p-%p-%p state=%d\n", (uintptr)s->start<<PageShift, s->limit, (uintptr)(s->start+s->npages)<<PageShift, s->state);
 					if(ptrmask != nil)
-						runtime·throw("bad pointer");
+						runtime·throw("invalid heap pointer");
 					// Add to badblock list, which will cause the garbage collection
 					// to keep repeating until it has traced the chain of pointers
 					// leading to obj all the way back to a root.
@@ -1459,6 +1459,7 @@ gc(struct gc_args *args)
 	t4 = runtime·nanotime();
 	runtime·atomicstore64(&mstats.last_gc, runtime·unixnanotime());  // must be Unix time to make sense to user
 	mstats.pause_ns[mstats.numgc%nelem(mstats.pause_ns)] = t4 - t0;
+	mstats.pause_end[mstats.numgc%nelem(mstats.pause_end)] = t4;
 	mstats.pause_total_ns += t4 - t0;
 	mstats.numgc++;
 	if(mstats.debuggc)
@@ -1572,7 +1573,7 @@ readgcstats_m(void)
 {
 	Slice *pauses;	
 	uint64 *p;
-	uint32 i, n;
+	uint32 i, j, n;
 	
 	pauses = g->m->ptrarg[0];
 	g->m->ptrarg[0] = nil;
@@ -1581,25 +1582,29 @@ readgcstats_m(void)
 	if(pauses->cap < nelem(mstats.pause_ns)+3)
 		runtime·throw("runtime: short slice passed to readGCStats");
 
-	// Pass back: pauses, last gc (absolute time), number of gc, total pause ns.
+	// Pass back: pauses, pause ends, last gc (absolute time), number of gc, total pause ns.
 	p = (uint64*)pauses->array;
 	runtime·lock(&runtime·mheap.lock);
+
 	n = mstats.numgc;
 	if(n > nelem(mstats.pause_ns))
 		n = nelem(mstats.pause_ns);
-	
+
 	// The pause buffer is circular. The most recent pause is at
 	// pause_ns[(numgc-1)%nelem(pause_ns)], and then backward
 	// from there to go back farther in time. We deliver the times
 	// most recent first (in p[0]).
-	for(i=0; i<n; i++)
+	for(i=0; i<n; i++) {
-		p[i] = mstats.pause_ns[(mstats.numgc-1-i)%nelem(mstats.pause_ns)];
+		j = (mstats.numgc-1-i)%nelem(mstats.pause_ns);
+		p[i] = mstats.pause_ns[j];
+		p[n+i] = mstats.pause_end[j];
+	}
 
-	p[n] = mstats.last_gc;
+	p[n+n] = mstats.last_gc;
-	p[n+1] = mstats.numgc;
+	p[n+n+1] = mstats.numgc;
-	p[n+2] = mstats.pause_total_ns;	
+	p[n+n+2] = mstats.pause_total_ns;	
 	runtime·unlock(&runtime·mheap.lock);
-	pauses->len = n+3;
+	pauses->len = n+n+3;
 }
 
 void

src/runtime/print1.go

@@ -19,32 +19,17 @@ func bytes(s string) (ret []byte) {
 	return
 }
 
-// goprintf is the function call that is actually deferred when you write
+// printf is only called from C code. It has no type information for the args,
-//	defer print(...)
+// but C stacks are ignored by the garbage collector anyway, so having
-// It is otherwise unused. In particular it is not used for ordinary prints.
+// type information would not add anything.
-// Right now a dynamically allocated string that is being passed as an
-// argument is invisible to the garbage collector and might be collected
-// if that argument list is the only reference. For now we ignore that possibility.
-// To fix, we should change to defer a call to vprintf with a pointer to
-// an argument list on the stack, stored in an appropriately typed
-// struct. golang.org/issue/8614.
-//go:nosplit
-func goprintf(s string) {
-	vprintf(s, add(unsafe.Pointer(&s), unsafe.Sizeof(s)))
-}
-
-// printf is only called from C code. It has the same problem as goprintf
-// with strings possibly being collected from underneath.
-// However, the runtime never prints dynamically allocated
-// Go strings using printf. The strings it prints come from the symbol
-// and type tables.
 //go:nosplit
 func printf(s *byte) {
 	vprintf(gostringnocopy(s), add(unsafe.Pointer(&s), unsafe.Sizeof(s)))
 }
 
-// sprintf is only called from C code.
+// sprintf is only called from C code. It has no type information for the args,
-// It has the same problem as goprintf.
+// but C stacks are ignored by the garbage collector anyway, so having
+// type information would not add anything.
 //go:nosplit
 func snprintf(dst *byte, n int32, s *byte) {
 	buf := (*[1 << 30]byte)(unsafe.Pointer(dst))[0:n:n]

src/runtime/proc.c

@@ -2758,6 +2758,8 @@ static void
 checkdead(void)
 {
 	G *gp;
+	P *p;
+	M *mp;
 	int32 run, grunning, s;
 	uintptr i;
 
@@ -2799,6 +2801,24 @@ checkdead(void)
 	runtime·unlock(&runtime·allglock);
 	if(grunning == 0)  // possible if main goroutine calls runtime·Goexit()
 		runtime·throw("no goroutines (main called runtime.Goexit) - deadlock!");
+
+	// Maybe jump time forward for playground.
+	if((gp = runtime·timejump()) != nil) {
+		runtime·casgstatus(gp, Gwaiting, Grunnable);
+		globrunqput(gp);
+ 		p = pidleget();
+ 		if(p == nil)
+ 			runtime·throw("checkdead: no p for timer");
+ 		mp = mget();
+ 		if(mp == nil)
+ 			newm(nil, p);
+ 		else {
+ 			mp->nextp = p;
+ 			runtime·notewakeup(&mp->park);
+ 		}
+ 		return;
+ 	}
+
 	g->m->throwing = -1;  // do not dump full stacks
 	runtime·throw("all goroutines are asleep - deadlock!");
 }

src/runtime/rt0_nacl_amd64p32.s

@@ -26,5 +26,5 @@ TEXT _rt0_amd64p32_nacl(SB),NOSPLIT,$16
 TEXT main(SB),NOSPLIT,$0
 	// Uncomment for fake time like on Go Playground.
 	//MOVQ	$1257894000000000000, AX
-	//MOVQ	AX, runtime·timens(SB)
+	//MOVQ	AX, runtime·faketime(SB)
 	JMP	runtime·rt0_go(SB)

src/runtime/runtime.c

@@ -282,9 +282,13 @@ struct DbgVar
 	int32*	value;
 };
 
+// Do we report invalid pointers found during stack or heap scans?
+int32 runtime·invalidptr = 1;
+
 #pragma dataflag NOPTR /* dbgvar has no heap pointers */
 static DbgVar dbgvar[] = {
 	{"allocfreetrace", &runtime·debug.allocfreetrace},
+	{"invalidptr", &runtime·invalidptr},
 	{"efence", &runtime·debug.efence},
 	{"gctrace", &runtime·debug.gctrace},
 	{"gcdead", &runtime·debug.gcdead},

src/runtime/runtime.h

@@ -657,6 +657,8 @@ enum {
 byte*	runtime·startup_random_data;
 uint32	runtime·startup_random_data_len;
 
+int32	runtime·invalidptr;
+
 enum {
 	// hashinit wants this many random bytes
 	HashRandomBytes = 32

src/runtime/stack.c

@@ -401,12 +401,12 @@ adjustpointers(byte **scanp, BitVector *bv, AdjustInfo *adjinfo, Func *f)
 			break;
 		case BitsPointer:
 			p = scanp[i];
-			if(f != nil && (byte*)0 < p && (p < (byte*)PageSize || (uintptr)p == PoisonGC || (uintptr)p == PoisonStack)) {
+			if(f != nil && (byte*)0 < p && (p < (byte*)PageSize && runtime·invalidptr || (uintptr)p == PoisonGC || (uintptr)p == PoisonStack)) {
 				// Looks like a junk value in a pointer slot.
 				// Live analysis wrong?
 				g->m->traceback = 2;
 				runtime·printf("runtime: bad pointer in frame %s at %p: %p\n", runtime·funcname(f), &scanp[i], p);
-				runtime·throw("bad pointer!");
+				runtime·throw("invalid stack pointer");
 			}
 			if(minp <= p && p < maxp) {
 				if(StackDebug >= 3)

src/runtime/sys_nacl_amd64p32.s

@@ -60,7 +60,7 @@ TEXT syscall·naclWrite(SB), NOSPLIT, $24-20
 TEXT runtime·write(SB),NOSPLIT,$16-20
 	// If using fake time and writing to stdout or stderr,
 	// emit playback header before actual data.
-	MOVQ runtime·timens(SB), AX
+	MOVQ runtime·faketime(SB), AX
 	CMPQ AX, $0
 	JEQ write
 	MOVL fd+0(FP), DI
@@ -242,7 +242,7 @@ TEXT runtime·mmap(SB),NOSPLIT,$8
 	RET
 
 TEXT time·now(SB),NOSPLIT,$16
-	MOVQ runtime·timens(SB), AX
+	MOVQ runtime·faketime(SB), AX
 	CMPQ AX, $0
 	JEQ realtime
 	MOVQ $0, DX
@@ -277,7 +277,7 @@ TEXT runtime·nacl_clock_gettime(SB),NOSPLIT,$0
 	RET
 
 TEXT runtime·nanotime(SB),NOSPLIT,$16
-	MOVQ runtime·timens(SB), AX
+	MOVQ runtime·faketime(SB), AX
 	CMPQ AX, $0
 	JEQ 3(PC)
 	MOVQ	AX, ret+0(FP)

src/runtime/time.go

@@ -35,8 +35,8 @@ var timers struct {
 	t            []*timer
 }
 
-// nacl fake time support.
+// nacl fake time support - time in nanoseconds since 1970
-var timens int64
+var faketime int64
 
 // Package time APIs.
 // Godoc uses the comments in package time, not these.
@@ -194,7 +194,7 @@ func timerproc() {
 			f(arg, seq)
 			lock(&timers.lock)
 		}
-		if delta < 0 {
+		if delta < 0 || faketime > 0 {
 			// No timers left - put goroutine to sleep.
 			timers.rescheduling = true
 			goparkunlock(&timers.lock, "timer goroutine (idle)")
@@ -208,6 +208,29 @@ func timerproc() {
 	}
 }
 
+func timejump() *g {
+	if faketime == 0 {
+		return nil
+	}
+
+	lock(&timers.lock)
+	if !timers.created || len(timers.t) == 0 {
+		unlock(&timers.lock)
+		return nil
+	}
+
+	var gp *g
+	if faketime < timers.t[0].when {
+		faketime = timers.t[0].when
+		if timers.rescheduling {
+			timers.rescheduling = false
+			gp = timers.gp
+		}
+	}
+	unlock(&timers.lock)
+	return gp
+}
+
 // Heap maintenance algorithms.
 
 func siftupTimer(i int) {

src/syscall/fs_nacl.go

@@ -818,6 +818,12 @@ func create(name string, mode uint32, sec int64, data []byte) error {
 	fs.mu.Unlock()
 	f, err := fs.open(name, O_CREATE|O_EXCL, mode)
 	if err != nil {
+		if mode&S_IFMT == S_IFDIR {
+			ip, _, err := fs.namei(name, false)
+			if err == nil && (ip.Mode&S_IFMT) == S_IFDIR {
+				return nil // directory already exists
+			}
+		}
 		return err
 	}
 	ip := f.(*fsysFile).inode

src/syscall/route_bsd.go

@@ -153,7 +153,7 @@ func (m *InterfaceAddrMessage) sockaddr() (sas []Sockaddr) {
 	// RTAX_NETMASK socket address on the FreeBSD kernel.
 	preferredFamily := uint8(AF_UNSPEC)
 	for i := uint(0); i < RTAX_MAX; i++ {
-		if m.Header.Addrs&rtaIfaMask&(1<<i) == 0 {
+		if m.Header.Addrs&(1<<i) == 0 {
 			continue
 		}
 		rsa := (*RawSockaddr)(unsafe.Pointer(&b[0]))

test/fixedbugs/issue9006.go

@@ -0,0 +1,37 @@
+// run
+
+// Copyright 2014 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 main
+
+type T1 struct {
+	X int
+}
+
+func NewT1(x int) T1 { return T1{x} }
+
+type T2 int
+
+func NewT2(x int) T2 { return T2(x) }
+
+func main() {
+	switch (T1{}) {
+	case NewT1(1):
+		panic("bad1")
+	case NewT1(0):
+		// ok
+	default:
+		panic("bad2")
+	}
+
+	switch T2(0) {
+	case NewT2(2):
+		panic("bad3")
+	case NewT2(0):
+		// ok
+	default:
+		panic("bad4")
+	}
+}

test/maplinear.go

@@ -44,14 +44,21 @@ func checkLinear(typ string, tries int, f func(n int)) {
 			}
 			return
 		}
-		fails++
+		// If n ops run in under a second and the ratio
-		if fails == 6 {
+		// doesn't work out, make n bigger, trying to reduce
+		// the effect that a constant amount of overhead has
+		// on the computed ratio.
+		if t1 < 1*time.Second {
+			n *= 2
+			continue
+		}
+		// Once the test runs long enough for n ops,
+		// try to get the right ratio at least once.
+		// If five in a row all fail, give up.
+		if fails++; fails >= 5 {
 			panic(fmt.Sprintf("%s: too slow: %d inserts: %v; %d inserts: %v\n",
 				typ, n, t1, 2*n, t2))
 		}
-		if fails < 4 {
-			n *= 2
-		}
 	}
 }