- always set the Pkg field in QualifiedIdents
- call Context.Ident for all identifiers in the AST that denote
  a types.Object (bug fix)
- added test that Context.Ident is called for all such identifiers

R=adonovan
CC=golang-dev
https://golang.org/cl/7101054

Fixes #4622

R=golang-dev, dave, dvyukov
CC=golang-dev
https://golang.org/cl/7103046

R=adonovan
CC=golang-dev
https://golang.org/cl/7103055

Also re-enabled resolver test.

R=adonovan
CC=golang-dev
https://golang.org/cl/7107043

Fixes #4634.

R=adg, kevlar
CC=golang-dev
https://golang.org/cl/7066053

R=dave, rsc
CC=golang-dev
https://golang.org/cl/7039044

Fixes #4222.
Fixes #4628.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/7100049

R=golang-dev, kevlar
CC=adg, golang-dev
https://golang.org/cl/7093056

Fixes #4647.

R=r, golang-dev
CC=golang-dev
https://golang.org/cl/7085051

R=dsymonds
CC=golang-dev
https://golang.org/cl/7106044

It's possible to view the package docs in plain text, eg:
        http://golang.org/pkg/time/?m=text
and this CL introduces the ability to do the same for files:
        http://golang.org/src/pkg/time/time.go?m=text

R=golang-dev, dave, minux.ma
CC=golang-dev
https://golang.org/cl/7085054

Completely removed *ast.Objects from being exposed by the
types API. *ast.Objects are still required internally for
resolution, but now the door is open for an internal-only
rewrite of identifier resolution entirely at type-check
time. Once that is done, ASTs can be type-checked whether
they have been created via the go/parser or otherwise,
and type-checking does not require *ast.Object or scope
invariants to be maintained externally.

R=adonovan
CC=golang-dev
https://golang.org/cl/7096048

R=minux.ma, lucio.dere
CC=golang-dev
https://golang.org/cl/7094048

Also undo revision a5b96b602690 used to workaround the bug.

Fixes #4643.

R=rsc, golang-dev, dave, minux.ma, lucio.dere, bradfitz
CC=golang-dev
https://golang.org/cl/7090043

runoutput styles tests generally consume a lot of memory. On arm platforms rotate?.go consume around 200mb each to compile, and as tests are sorted alphabetically, they all tend to run at once.

This change limits the number of runoutput jobs to 2 on arm platforms.

R=minux.ma, remyoudompheng, bradfitz, lucio.dere
CC=golang-dev
https://golang.org/cl/7099047

R=golang-dev, minux.ma, rsc, ality, seed
CC=golang-dev
https://golang.org/cl/7034052

Fixes #4642.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/7090044

Fixes #4640.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/7082044

Fixes #4485.

R=golang-dev, rsc, adg
CC=golang-dev
https://golang.org/cl/7071050

Fixes #4645

R=golang-dev, alex.brainman, minux.ma
CC=golang-dev
https://golang.org/cl/7105047

R=adonovan
CC=golang-dev
https://golang.org/cl/7103047

Fixes #3460

R=golang-dev, alex.brainman
CC=golang-dev
https://golang.org/cl/7096046

The existing type checker was relying on augmenting ast.Object
fields (empty interfaces) for its purposes. While this worked
for some time now, it has become increasingly brittle. Also,
the need for package information for Fields and Methods would
have required a new field in each ast.Object. Rather than making
them bigger and the code even more subtle, in this CL we are moving
away from ast.Objects.

The types packge now defines its own objects for different
language entities (Const, Var, TypeName, Func), and they
implement the types.Object interface. Imported packages
create a Package object which holds the exported entities
in a types.Scope of types.Objects.

For type-checking, the current package is still using ast.Objects
to make this transition manageable. In a next step, the type-
checker will also use types.Objects instead, which opens the door
door to resolving ASTs entirely by the type checker. As a result,
the AST and type checker become less entangled, and ASTs can be
manipulated "by hand" or programmatically w/o having to worry
about scope and object invariants that are very hard to maintain.

(As a consequence, a future parser can do less work, and a
future AST will not need to define objects and scopes anymore.
Also, object resolution which is now split across the parser,
the ast, (ast.NewPackage), and even the type checker (for composite
literal keys) can be done in a single place which will be simpler
and more efficient.)

Change details:
- Check now takes a []*ast.File instead of a map[string]*ast.File.
It's easier to handle (I deleted code at all use sites) and does
not suffer from undefined order (which is a pain for testing).
- ast.Object.Data is now a *types.Package rather then an *ast.Scope
if the object is a package (obj.Kind == ast.Pkg). Eventually this
will go away altogether.
- Instead of an ast.Importer, Check now uses a types.Importer
(which returns a *types.Package).
- types.NamedType has two object fields (Obj Object and obj *ast.Object);
eventually there will be only Obj. The *ast.Object is needed during
this transition since a NamedType may refer to either an imported
(using types.Object) or locally defined (using *ast.Object) type.
- ast.NewPackage is not used anymore - there's a local copy for
package-level resolution of imports.
- struct fields now take the package origin into account.
- The GcImporter is now returning a *types.Package. It cannot be
used with ast.NewPackage anymore. If that functionality is still
used, a copy of the old GcImporter should be made locally (note
that GcImporter was part of exp/types and it's API was not frozen).
- dot-imports are not handled for the time being (this will come back).

R=adonovan
CC=golang-dev
https://golang.org/cl/7058060

Update #4139.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/7094047

Fixes #3678.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/6460087

The -I. syntax now needs a space to be recognized in the
compiler.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7098046

This allows test/dwarf to be supported by run.go.

Update #4139.

R=golang-dev, bradfitz, iant
CC=golang-dev
https://golang.org/cl/7064067

This introduces a buffer between writing from a handler and
writing chunks.  Further, it delays writing the header until
the first full chunk is ready.  In the case where the first
full chunk is also the final chunk (for small responses), that
means we can also compute a Content-Length, which is a nice
side effect for certain benchmarks.

Fixes #2357

R=golang-dev, dave, minux.ma, rsc, adg, balasanjay
CC=golang-dev
https://golang.org/cl/6964043

Update #2656

R=golang-dev, iant, minux.ma, bradfitz
CC=golang-dev
https://golang.org/cl/7065063

The peephole optimizer would keep hands off AX and X0 during returns, even though go doesn't return through registers.

R=dave, rsc
CC=golang-dev
https://golang.org/cl/7030046

Fixes #4583.

R=golang-dev, minux.ma, bradfitz, rsc, dave
CC=golang-dev
https://golang.org/cl/6976050

R=golang-dev, dave, rsc
CC=golang-dev
https://golang.org/cl/7066052

Modeled after CL 7030046 by daniel.morsing.

example program:
func f(x int) int { x -= 10; return x }

5g -S difference:
 --- prog list "f" ---
 0011 (x.go:7) TEXT   	add+0(SB),$0-8
 0012 (x.go:7) MOVW   	x+0(FP),R0
-0013 (x.go:7) SUB    	$10,R0,R2
-0014 (x.go:7) MOVW   	R2,R0
-0015 (x.go:7) MOVW   	R2,.noname+4(FP)
-0016 (x.go:7) RET    	,
+0013 (x.go:7) SUB    	$10,R0
+0014 (x.go:7) MOVW   	R0,.noname+4(FP)
+0015 (x.go:7) RET    	,

R=dave, rsc
CC=golang-dev
https://golang.org/cl/7030047

also added appropriate docs to cmd/ld/doc.go
(largely copied from Russ's CL 6938073).

R=rsc
CC=golang-dev
https://golang.org/cl/7004049

Skip most of the scanning and parsing logic for simple (non-object/array) JSON values.

benchmark                   old ns/op    new ns/op    delta
BenchmarkUnmarshalInt             948          436  -54.01%
BenchmarkUnmarshalUint            930          427  -54.09%
BenchmarkUnmarshalString         1407          715  -49.18%
BenchmarkUnmarshalFloat          1114          536  -51.89%
BenchmarkUnmarshalBool            759          266  -64.95%
BenchmarkUnmarshalStruct         8165         8181   +0.20%

No significant effects on the go1 benchmarks:

benchmark                 old ns/op    new ns/op    delta
BenchmarkBinaryTree17    9647362752   9596196417   -0.53%
BenchmarkFannkuch11      5623613048   5518694872   -1.87%
BenchmarkGobDecode         32944041     33165434   +0.67%
BenchmarkGobEncode         21237482     21080554   -0.74%
BenchmarkGzip             750955920    749861980   -0.15%
BenchmarkGunzip           197369742    197886192   +0.26%
BenchmarkJSONEncode        79274091     78891137   -0.48%
BenchmarkJSONDecode       180257802    175280358   -2.76%
BenchmarkMandelbrot200      7396666      7388266   -0.11%
BenchmarkParse             11446460     11386550   -0.52%
BenchmarkRevcomp         1605152523   1599512029   -0.35%
BenchmarkTemplate         204538247    207765574   +1.58%

benchmark                  old MB/s     new MB/s  speedup
BenchmarkGobDecode            23.30        23.14    0.99x
BenchmarkGobEncode            36.14        36.41    1.01x
BenchmarkGzip                 25.84        25.88    1.00x
BenchmarkGunzip               98.32        98.06    1.00x
BenchmarkJSONEncode           24.48        24.60    1.00x
BenchmarkJSONDecode           10.76        11.07    1.03x
BenchmarkParse                 5.06         5.09    1.01x
BenchmarkRevcomp             158.34       158.90    1.00x
BenchmarkTemplate              9.49         9.34    0.98x

Fixes #3949.

R=golang-dev, dave, bradfitz, timo
CC=golang-dev
https://golang.org/cl/7068043

Update #2631.
Update #3097.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/7061060

Fixes #2656.

R=golang-dev, bradfitz, iant, minux.ma
CC=golang-dev
https://golang.org/cl/7062057

5c miscompiles *p++ = struct_literal.

R=dave, golang-dev
CC=golang-dev
https://golang.org/cl/7065069

R=rsc, dvyukov, remyoudompheng, dave, minux.ma, bradfitz
CC=golang-dev
https://golang.org/cl/6945069

Generated by addca.

R=gobot
CC=golang-dev
https://golang.org/cl/7057067