mirror
/
go
mirror of https://github.com/golang/go.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

doc: finish the small library changes in go1.5.html; start work on tools 

Also add words about the assembler.

Change-Id: I9bd8cc88076f06b0eef36a07f57d1ad5d9261d8d
Reviewed-on: https://go-review.googlesource.com/11853
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This commit is contained in:
Rob Pike 2015-07-02 12:56:51 +10:00
parent 11f50f41ee
commit 09b5463d9b
1 changed files with 225 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

262
doc/go1.5.html
View File

@ -241,30 +241,86 @@ cmd/gc: add -dynlink option (for amd64 only)
cmd/ld: add -buildmode option
cmd/trace: new command to view traces (https://golang.org/cl/3601)
Assembler:
New cmd/asm tool (now use go tool asm, not go tool 6a)
Assembler now supports -dynlink option.
ARM assembly syntax has had some features removed.
- mentioning SP or PC as a hardware register
These are always pseudo-registers except that in some contexts
they're not, and it's confusing because the context should not affect
which register you mean. Change the references to the hardware
registers to be explicit: R13 for SP, R15 for PC.
- constant creation using assignment
The files say a=b when they could instead say #define a b.
There is no reason to have both mechanisms.
- R(0) to refer to R0.
Some macros use this to a great extent. Again, it's easy just to
use a #define to rename a register.
Also expression evaluation now uses uint64s instead of signed integers and the
precedence of operators is now Go-like rather than C-like.
</pre>
<h3 id="assembler">Assembler</h3>
<p>
The assembler in Go 1.5 is a single new Go program that replaces
the suite of C-language assemblers (<code>6a</code>,
<code>8a</code>, etc.) in previous releases.
The values of the environmetn variables
<code>GOARCH</code> and <code>GOOS</code>
choose which architecture and operating system the generated
code will be for.
This is practical because the assembly language syntax has always
been idiosyncratic and nearly uniform across architectures;
what differs is just the list of instructions available and the
syntax of some addressing modes.
With the variation easily configured at startup, a single
assembler binary can cover all architectures.
(See the updated <a href="/doc/asm">assembler guide</a>
for more information about the language and some of
the changes listed below.)
</p>
<p>
The new assembler is very nearly compatible with the previous
one, but there are a few changes that may affect some
assembler source files.
</p>
<p>
First, the expression evaluation used for constants is a little
different.
It now uses unsigned 64-bit arithmetic and the precedence
of operators (<code>+</code>, <code>-</code>, <code><<</code>, etc.)
comes from Go, not C.
Since there are few assembly programs to start with, and few use
complex arithmetic expressions,
and of those even fewer will be affected by these changes, we expect
almost no programs will need to be updated.
</p>
<p>
Perhaps more important is that some discrepancies between the
architectures in how the PC and SP are handled have been
eliminated.
Sometimes these registers represented hardware
registers, and sometimes pseudo-registers.
As of Go 1.5, the names <code>PC</code> and <code>SP</code>
are always pseudo-registers.
To refer to the hardware register, use the alternate representation such
as <code>R13</code> for the stack pointer and
<code>R15</code> for the hardware program counter on x86.
(The names are different on other architectures.)
To help enforce this change, references to the
<code>SP</code> and <code>PC</code>
pseudo-registers now always require an identifier:
<code>f+4(SP)</code> not <code>4(SP)</code>;
it is a syntax error to omit the identifier.
Uses of <code>SP</code> (say) as a hardware register
tend to omit the name, and they will now be flagged by
the assembler.
</p>
<p>
One minor change is that some of the old assemblers
permitted the notation
</p>
<pre>
constant=value
</pre>
<p>
to define a named constant.
Since this is always possible to do with the traditional
C-like <code>#define</code> notation, which is still
supported (the assembler includes an implementation
of a simplified C preprocessor), the feature was removed.
</p>
<h2 id="performance">Performance</h2>
<pre>
@ -465,43 +521,86 @@ function that locates the rightmost byte with that value in the argument.
</li>
<li>
TODO crypto/cipher: clarify what will happen if len(src) != len(dst) for the Stream interface. (https://golang.org/cl/1754)
The <a href="/pkg/crypto/"><code>crypto</code></a> package
has a new interface, <a href="/pkg/crypto/#Decrypter"><code>Decrypter</code></a>,
that abstracts the behavior of a private key used in asymmetric decryption.
</li>
<li>
TODO crypto/cipher: support non-standard nonce lengths for GCM. (https://golang.org/cl/8946)
In the <a href="/pkg/crypto/cipher/"><code>crypto/cipher</code></a> package,
the documentation for the <a href="/pkg/crypto/cipher/#Stream"><code>Stream</code></a>
interface has been clarified regarding the behavior when the source and destination are
different lengths.
If the destination is shorter than the source, the method will panic.
This is not a change in the implementation, only the documentation.
</li>
<li>
TODO crypto/elliptic: add Name field to CurveParams struct (https://golang.org/cl/2133)
Also in the <a href="/pkg/crypto/cipher/"><code>crypto/cipher</code></a> package,
there is now support for nonce lengths other than 96 bytes in AES's Galois/Counter mode (GCM),
which some protocols require.
</li>
<li>
TODO crypto/elliptic: Unmarshaling points now automatically checks that the point is on the curve (https://golang.org/cl/2421)
In the <a href="/pkg/crypto/elliptic/"><code>crypto/elliptic</code></a> package,
there is now a <code>Name</code> field in the
<a href="/pkg/crypto/elliptic/#CurveParams"><code>CurveParams</code></a> struct,
and the curves implemented in the package have been given names.
These names provide a safer way to select a curve, as opposed to
selecting its bit size, for cryptographic systems that are curve-dependent.
</li>
<li>
TODO crypto/tls: change default minimum version to TLS 1.0. (https://golang.org/cl/1791)
Also in the <a href="/pkg/crypto/elliptic/"><code>crypto/elliptic</code></a> package,
the <a href="/pkg/crypto/elliptic/#Unmarshal"><code>Unmarshal</code></a> function
now verifies that the point is actually on the curve.
(If it is not, the function returns nils).
This change guards against certain attacks.
</li>
<li>
TODO crypto/tls: including Certificate Transparency SCTs in the handshake is now supported (https://golang.org/cl/8988)
The <a href="/pkg/crypto/tls/"><code>crypto/tls</code></a> package
now defaults to TLS 1.0.
The old default, SSLv3, is still available through <a href="/pkg/crypto/tls/#Config"><code>Config</code></a> if needed.
</li>
<li>
TODO crypto/tls: session ticket keys can now be rotated at runtime (https://golang.org/cl/9072)
Also, the <a href="/pkg/crypto/tls/"><code>crypto/tls</code></a> package
now supports Signed Certificate Timestamps (SCTs) as specified in RFC 6962.
The server serves them if they are listed in the
<a href="/pkg/crypto/tls/#Certificate"><code>Certificate</code></a> struct,
and the client reqeusts them and exposes them, if present,
in its <a href="/pkg/crypto/tls/#ConnectionState"><code>ConnectionState</code></a> struct.
The <a href="/pkg/crytpo/tls/"><code>crytpo/tls</code></a> server implementation
will also now always call the
<code>GetCertificate</code> function in
the <a href="/pkg/crypto/tls/#Config"><code>Config</code></a> struct
to select a certificate for the connection when none is supplied.
</li>
<li>
TODO crypto/tls: servers will now always call GetCertificate to pick a certificate for a connection when Certificates is empty (https://golang.org/cl/8792)
Finally, the session ticket keys in the
<a href="/pkg/crypto/tls/"><code>crypto/tls</code></a> package
can now be rotated (changed periodically during an active connection).
This is done through the new
<a href="/pkg/crypto/tls/#Config.SetSessionTicketKeys"><code>SetSessionTicketKeys</code></a>
method of the
<a href="/pkg/crypto/tls/#Config"><code>Config</code></a> type.
</li>
<li>
TODO crypto/x509: wildcards are now only accepted as the first label (https://golang.org/cl/5691)
In the <a href="/pkg/crypto/x509/"><code>crypto/x509</code></a> package,
wildcards are now accepted only in the leftmost label as defined in
<a href="https://tools.ietf.org/html/rfc6125#section-6.4.3">the specification</a>.
</li>
<li>
TODO crypto/x509: unknown critical extensions now cause errors in Verify, not when parsing (https://golang.org/cl/9390)
Also in the <a href="/pkg/crypto/x509/"><code>crypto/x509</code></a> package,
the handling of unknown critical extensions has been changed.
They used to cause parse errors but now they are parsed and caused errors only
in <a href="/pkg/crypto/x509/#Certificate.Verify"><code>Verify</code></a>.
The new field <code>UnhandledCriticalExtensions</code> of
<a href="/pkg/crypto/x509/#Certificate"><code>Certificate</code></a> records these extensions.
</li>
<li>
@ -511,6 +610,18 @@ now has a <a href="/pkg/database/sql/#DB.Stats"><code>Stats</code></a> method
to retrieve database statistics.
</li>
<li>
The <a href="/pkg/debug/dwarf/"><code>debug/dwarf</code></a>
package has extensive additions to better support DWARF version 4.
See for example the definition of the new type
<a href="/pkg/debug/dwarf/#Class"><code>Class</code></a>.
</li>
<li>
The <a href="/pkg/debug/elf/"><code>debug/elf</code></a>
package now has support for the 64-bit Power architecture.
</li>
<li>
The <a href="/pkg/encoding/base64/"><code>encoding/base64</code></a> package
now supports unpadded encodings through two new encoding variables,
@ -518,6 +629,20 @@ now supports unpadded encodings through two new encoding variables,
<a href="/pkg/encoding/base64/#RawURLEncoding"><code>RawURLEncoding</code></a>.
</li>
<li>
The <a href="/pkg/encoding/json/"><code>encoding/json</code></a> package
now returns an <a href="/pkg/encoding/json/#UnmarshalTypeError"><code>UnmarshalTypeError</code></a>
if a JSON value is not appropriate for the target variable or component
to which it is being unmarshaled.
</li>
<li>
The <a href="/pkg/flag/"><code>flag</code></a> package
has a new function, <a href="/pkg/flag/#UnquoteUsage"><code>UnquoteUsage</code></a>,
to assist in the creation of usage messages using the new convention
described above.
</li>
<li>
Also in the <a href="/pkg/fmt/"><code>fmt</code></a> package,
a value of type <a href="/pkg/reflect/#Value"><code>Value</code></a> now
@ -536,6 +661,9 @@ semicolon was implicitly added or was present in the source.
For forward compatibility the <a href="/pkg/go/build/"><code>go/build</code></a> package
reserves <code>GOARCH</code> values for a number of architectures that Go might support one day.
This is not a promise that it will.
Also, the <a href="/pkg/go/build/#Package"><code>Package</code></a> struct
now has a <code>PkgTargetRoot</code> field that stores the
architecture-dependent root directory in which to install, if known.
</li>
<li>
@ -548,6 +676,39 @@ rules since code that uses the package must explicitly ask for it at its new loc
TODO: There should be a gofix for this.
</li>
<li>
In the <a href="/pkg/image/"><code>image</code></a> package,
the <a href="/pkg/image/#Rectangle"><code>Rectangle</code></a> type
now implements the <a href="/pkg/image/#Image"><code>Image</code></a> interface,
mask image when drawing.
</li>
<li>
Also in the <a href="/pkg/image/"><code>image</code></a> package,
to assist in the handling of some JPEG images,
there is now support for 4:1:1 and 4:1:0 YCbCr subsampling and basic
CMYK support, represented by the new image.CMYK struct.
</li>
<li>
The <a href="/pkg/image/color/"><code>image/color</code></a> package
adds basic CMYK support, through the new
<a href="/pkg/image/color/#CMYK"><code>CMYK</code></a> struct,
the <a href="/pkg/image/color/#CMYKModel"><code>CMYKModel</code></a> color model, and the
<a href="/pkg/image/color/#CMYKToRGB"><code>CMYKToRGB</code></a> function, as
needed by some JPEG images.
</li>
<li>
The <a href="/pkg/image/gif/"><code>image/gif</code></a> package
includes a couple of generalizations.
A multiple-frame GIF file can now have an overall bounds different
from all the contained single frames' bounds.
Also, the <a href="/pkg/image/gif/#GIF"><code>GIF</code></a> struct
now has a <code>Disposal</code> field
that specifies the disposal method for each frame.
</li>
<li>
The <a href="/pkg/io/"><code>io</code></a> package
adds a <a href="/pkg/io/#CopyBuffer"><code>CopyBuffer</code></a> function
@ -579,7 +740,16 @@ method for the <a href="/pkg/math/big/#Int"><code>Int</code></a> type.
</li>
<li>
The <a href="/pkg/mime/"><code>mime</code></a> package adds an
The mime package
adds a new <a href="/pkg/mime/#WordDecoder"><code>WordDecoder</code></a> type
to decode MIME headers containing RFC 204-encoded words.
It also provides <a href="/pkg/mime/#BEncoding"><code>BEncoding</code></a> and
<a href="/pkg/mime/#QEncoding"><code>QEncoding</code></a>
as implementations of the encoding schemes of RFC 2045 and RFC 2047.
</li>
<li>
The <a href="/pkg/mime/"><code>mime</code></a> package also adds an
<a href="/pkg/mime/#ExtensionsByType"><code>ExtensionsByType</code></a>
function that returns the MIME extensions know to be associated with a given MIME type.
</li>
@ -609,10 +779,6 @@ type now includes a <code>Source</code> field that holds the local
network address.
</li>
<li>
TODO net: add SocketConn, SocketPacketConn (https://golang.org/cl/9275)
</li>
<li>
The <a href="/pkg/net/http/"><code>net/http</code></a> package now
has support for setting trailers from a server <a href="/pkg/net/http/#Handler"><code>Handler</code></a>.
@ -627,6 +793,14 @@ in the <a href="/pkg/net/#ServeContent"><code>ServeContent</code></a> function.
As of Go 1.5, it now also ignores a time value equal to the Unix epoch.
</li>
<li>
The <a href="/pkg/net/http/fcgi/"><code>net/http/fcgi</code></a> package
exports two new errors,
<a href="/pkg/net/http/fcgi/#ErrConnClosed"><code>ErrConnClosed</code></a> and
<a href="/pkg/net/http/fcgi/#ErrRequestAborted"><code>ErrRequestAborted</code></a>,
to report the corresponding error conditions.
</li>
<li>
The <a href="/pkg/net/http/cgi/"><code>net/http/cgi</code></a> package
had a bug that mishandled the values of the environment variables
@ -662,6 +836,20 @@ adds new <a href="/pkg/os/signal/#Ignore"><code>Ignore</code></a> and
<a href="/pkg/os/signal/#Reset"><code>Reset</code></a> functions.
</li>
<li>
The <a href="/pkg/runtime/"><code>runtime</code></a>,
<a href="/pkg/runtime/pprof/"><code>runtime/pprof</code></a>,
and <a href="/pkg/net/http/pprof/"><code>net/http/pprof</code></a> packages
each have new functions to support the tracing facilities described above:
<a href="/pkg/runtime/#ReadTrace"><code>ReadTrace</code></a>,
<a href="/pkg/runtime/#StartTrace"><code>StartTrace</code></a>,
<a href="/pkg/runtime/#StopTrace"><code>StopTrace</code></a>,
<a href="/pkg/runtime/pprof/#StartTrace"><code>StartTrace</code></a>,
<a href="/pkg/runtime/pprof/#StopTrace"><code>StopTrace</code></a>, and
<a href="/pkg/net/http/pprof/#Trace"><code>Trace</code></a>.
See the respective documentation for details.
</li>
<li>
The <a href="/pkg/runtime/pprof/"><code>runtime/pprof</code></a> package
by default now includes overall memory statistics in all memory profiles.