Starting it lazily causes a memory allocation (for the goroutine) during GC.

First use of channels for runtime implementation.

Change-Id: I9cd24dcadbbf0ee5070ee6d0ed7ea415504f316c
Reviewed-on: https://go-review.googlesource.com/6960
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Austin Clements <austin@google.com>

Previously, gc would compile code like

    func foo() { ... }
    var bar = foo

by emitting a static closure to wrap "foo", but then emitting runtime
initialization code to assign the closure to "bar".  This CL changes
gc to instead statically initialize "bar".

Notably, this change shrinks the "go" tool's text segment by ~7.4kB on
linux/amd64 while only increasing the data segment by ~100B:

   text	   data	    bss	    dec	    hex	filename
7237819	 122412	 215616	7575847	 739927	go.before
7230398	 122540	 215232	7568170	 737b2a	go.after

Fixes issue #10081.

Change-Id: If5e26cf46b323393ba6f2199a82a06e9e4baf411
Reviewed-on: https://go-review.googlesource.com/6880
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Remove the per-achitecture formatter for Prog and replace it with
a global String method. Clean up and regularize the output. Update
tests affected by the format; some tests are made correct now when
they were broken before (and known to be).

Also, related: Change the encoding of the (R1+R2) syntax on ppc64
to be equivalent to (R1)(R2*1), which means it needs no special
handling.

Delete the now unused STRINGSZ constant.

Change-Id: I7f6654d11f80065f3914a3f19353f2f12edfe310
Reviewed-on: https://go-review.googlesource.com/6931Reviewed-by: Russ Cox <rsc@golang.org>

Use optimized formatBits function to format mantissa and exponent.
Add benchmark for binary exponent float format.

on darwin/386

benchmark                         old ns/op     new ns/op     delta
BenchmarkAppendFloatBinaryExp     520           122           -76.54%

on darwin/amd64

benchmark                         old ns/op     new ns/op     delta
BenchmarkAppendFloatBinaryExp     76.9          84.3          +9.62%

Change-Id: If543552f1960e1655bed3a4130914e5eaa3aac69
Reviewed-on: https://go-review.googlesource.com/5600Reviewed-by: Robert Griesemer <gri@golang.org>

I asked for this in CL 3742 and it was ignored.

Change-Id: I30ad05f87c7d9eccb11df7e19288e3ed2c7e2e3f
Reviewed-on: https://go-review.googlesource.com/6930Reviewed-by: Dmitry Vyukov <dvyukov@google.com>

Change-Id: I815b685e261065bad3416b55feb4fec68974c9a0
Reviewed-on: https://go-review.googlesource.com/6896Reviewed-by: Rob Pike <r@golang.org>

Cleanup after https://go-review.googlesource.com/3742

Change-Id: Iff3ceffc31b778b1ed0b730696fce6d1b5124447
Reviewed-on: https://go-review.googlesource.com/6761Reviewed-by: Minux Ma <minux@golang.org>

With the new unificiation, the flag must be TYPE_CONST to print
properly.

Change-Id: I7cd1c56355724f08cbe9afc6ab7a66904031adc9
Reviewed-on: https://go-review.googlesource.com/6903Reviewed-by: Russ Cox <rsc@golang.org>

Change-Id: I3a2b17e218aa05cfb67d7561e0b52a6df766924d
Reviewed-on: https://go-review.googlesource.com/6897
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

This was in i386 but not in x86 and was missed during the merge.
Needed for linux/386.

Change-Id: Ia6e495c044f53bcb98f3bb03e20d8f6d35a8f8ff
Reviewed-on: https://go-review.googlesource.com/6902Reviewed-by: Rob Pike <r@golang.org>

Change-Id: If2872e73da4daa4ff1912883d30c8fc9754ef552
Reviewed-on: https://go-review.googlesource.com/6894Reviewed-by: Rob Pike <r@golang.org>

Now unused.

Change-Id: I0ba27e58721ad66cc3068346d6d31ba0ac37ad64
Reviewed-on: https://go-review.googlesource.com/6893Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>

Change-Id: I7d289c7f250e4db551192d52535a90974685f0b3
Reviewed-on: https://go-review.googlesource.com/6891Reviewed-by: Minux Ma <minux@golang.org>

Support the old syntax for AX:DX by rewriting into the new form,
AX, DX. Delete now-unnecessary hacks for some special cases.

Change-Id: Icd42697c7617f8a50864ca8b0c69469321a2296e
Reviewed-on: https://go-review.googlesource.com/6901Reviewed-by: Russ Cox <rsc@golang.org>

(Because that's what the assembly files actually say - no $ on the constant.)

Change-Id: Idb774cdca0e089c4ac24ab665e23290bf7b565bf
Reviewed-on: https://go-review.googlesource.com/6895Reviewed-by: Rob Pike <r@golang.org>

Nothing uses it, nothing should start using it.
Stop leaving plausible-looking values there.
It would be nice to remove entirely, but that would
require a new version number for the object file format,
in order not to break external readers like debug/gosym.
It's easier to leave and poison.

I came across an old mail thread suggesting we start using it
to speed up tracebacks. I want to make sure that doesn't happen.

(The values there were never quite right, and the number is
fundamentally PC-specific anyway.)

Change-Id: Iaf38e8a6b523cbae30b69c28497c4588ef397519
Reviewed-on: https://go-review.googlesource.com/6890Reviewed-by: Minux Ma <minux@golang.org>

Make cmd/internal/obj/x86 support 32-bit mode and use
instead of cmd/internal/obj/i386. Delete cmd/internal/obj/i386.

Clean up encoding of PINSRQ, CMPSD to use explicit third arg
instead of jamming it into an unused slot of a different arg.

Also fix bug in old6a, which declared the wrong grammar.
The accepted (and encoded) arguments to CMPSD etc are mem,reg not reg,mem.
Code that did try to use mem,reg before would be rejected by liblink,
so only reg,reg ever worked, so existing code is not affected.
After this change, code can use mem,reg successfully.

The real bug here is that the encoding tables inverted the argument
order, making the comparisons all backward from what they say on the page.
It's too late to swap them, though: people have already written code that
expects the inverted comparisons (like in package math, and likely externally).
The best we can do is make the argument that should and can take a
memory operand accept it.

Bit-for-bit compatibility checked against tree without this CL.

Change-Id: Ife5685bc98c95001f64407f35066b34b4dae11c1
Reviewed-on: https://go-review.googlesource.com/6810Reviewed-by: Rob Pike <r@golang.org>

Add unused (but initialized) from3 field to ytab, f3t to movtab.
Remove level of indentation in movtab processing.

Change-Id: I8475988f46b541ecaccf8d34608da8bef7d12e24
Reviewed-on: https://go-review.googlesource.com/6892Reviewed-by: Rob Pike <r@golang.org>

Node.Needzero only has two values and acts as a bool, so make it a bool.

Change-Id: Ica46e5ebafbe478017ea52ce6bb335f404059677
Reviewed-on: https://go-review.googlesource.com/6800Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Fixes #10066.

Change-Id: I43c423793dd094989e921e163a06b12181a35719
Signed-off-by: Shenghou Ma <minux@golang.org>
Reviewed-on: https://go-review.googlesource.com/6750
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Chris Manghane <cmang@golang.org>

Change-Id: I520a0f2c2d14f744a5d2e8cf93963eec1cf3e9ba
Signed-off-by: Shenghou Ma <minux@golang.org>
Reviewed-on: https://go-review.googlesource.com/6732Reviewed-by: Andrew Gerrand <adg@golang.org>

This avoids repeated allocation and map lookups
when constructing the pcln tables.

For 6g compiling cmd/internal/gc/*.go this saves about 8% wall time.

Change-Id: I6a1a80e278ae2c2a44bd1537015ea7b4e7a4d6ca
Reviewed-on: https://go-review.googlesource.com/6793Reviewed-by: Rob Pike <r@golang.org>

Remove blank lines and merge lone imports into blocks.

Change-Id: Ib46dad584456909969f1ba3a2c7f5667abf336ae
Reviewed-on: https://go-review.googlesource.com/6792Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

Change-Id: I764933f4928bb9d0d119fbfe44a193ce1449b61e
Reviewed-on: https://go-review.googlesource.com/6791Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

Change-Id: Ib813eb5960c3310b1c919f25f687560f4f9d63b0
Reviewed-on: https://go-review.googlesource.com/6820Reviewed-by: Russ Cox <rsc@golang.org>

For OSes that use elf on intel, 2*Ptrsize bytes are reserved for TLS.
But only one pointer (g) has been stored in the TLS for a while now.
So we can set it to just Ptrsize, which happily matches what happens
when externally linking.

Fixes #9913

Change-Id: Ic816369d3a55a8cdcc23be349b1a1791d53f5f81
Reviewed-on: https://go-review.googlesource.com/6584
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Accidental semantics change in 4c6364a8.

Change-Id: I0bbfc441662d79af4dbac6f9fc4e3a485adfb924
Reviewed-on: https://go-review.googlesource.com/6831Reviewed-by: Minux Ma <minux@golang.org>

Change-Id: I83de9d83708edc8d196bbcfdc7d2ba7ffaff50d2
Reviewed-on: https://go-review.googlesource.com/6586Reviewed-by: Rob Pike <r@golang.org>

Fixes #10072

Change-Id: I1f73c8829a89144d49433a36a4e64223c74af954
Reviewed-on: https://go-review.googlesource.com/6585Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: Ice4f78e74ec3025a974ffd9ca5e3d28bb3164f40
Reviewed-on: https://go-review.googlesource.com/6794Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Run-TryBot: David Crawshaw <crawshaw@golang.org>

Change-Id: Id1927180ecd18b849727225adea05465d36b3973
Reviewed-on: https://go-review.googlesource.com/6210Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

This is an experiment to see if removing the boundary bit logic will
lead to fewer cache misses and improved performance. Instead of using
boundary bits we use the span information to get element size and use
some bit whacking to get the boundary without having to touch the
random heap bits which cause cache misses.

Furthermore once the boundary bit is removed we can either use that
bit for a simpler checkmark routine or we can reduce the number of
bits in the GC bitmap to 2 bits per pointer sized work. For example
the 2 bits at the boundary can be used for marking and pointer/scalar
differentiation. Since we don't need the mark bit except at the
boundary nibble of the object other nibbles can use this bit
as a noscan bit to indicate that there are no more pointers in
the object.

Currently the changed included in this CL slows down the garbage
benchmark. With the boundary bits garbage gives 5.78 and without
(this CL) it gives 5.88 which is a 2% slowdown.

Change-Id: Id68f831ad668176f7dc9f7b57b339e4ebb6dc4c2
Reviewed-on: https://go-review.googlesource.com/6665Reviewed-by: Austin Clements <austin@google.com>

Change-Id: I932c2f1b1d27c437722cd27d2001b085a655c572
Reviewed-on: https://go-review.googlesource.com/6722Reviewed-by: Alan Donovan <adonovan@google.com>

Change-Id: Ide0615542d67b7d81bf6c56aab550e142a8789f7
Reviewed-on: https://go-review.googlesource.com/6682Reviewed-by: Alan Donovan <adonovan@google.com>

Change-Id: If04840c34b0ac5168ce1699eae880f04ae21c84c
Reviewed-on: https://go-review.googlesource.com/6680Reviewed-by: Alan Donovan <adonovan@google.com>

Shifts are trivially implemented by combining
Float.MantExp and Float.SetMantExp.

Change-Id: Ia2fb49297d8ea7aa7d64c8b1318dc3dc7c8af2f7
Reviewed-on: https://go-review.googlesource.com/6671Reviewed-by: Alan Donovan <adonovan@google.com>

This change represents Accuracy as a bit pattern rather than
an ordered value; with a new value Undef which is both Below
and Above.

Change-Id: Ibb96294c1417fb3cf2c3cf2374c993b0a4e106b3
Reviewed-on: https://go-review.googlesource.com/6650Reviewed-by: Alan Donovan <adonovan@google.com>

Change-Id: I9a6ebb747d5b9756c214bdeb19f60820602d7a24
Reviewed-on: https://go-review.googlesource.com/6340Reviewed-by: Alan Donovan <adonovan@google.com>

This change introduces NaNs (for situations like Inf-Inf, etc.).
The implementation is incomplete (the four basic operations produce
a NaN if any of the operands is an Inf or a NaN); and some operations
produce incorrect accuracy for NaN arguments. These are known bugs
which are documented.

Change-Id: Ia88841209e47930681cef19f113e178f92ceeb33
Reviewed-on: https://go-review.googlesource.com/6540Reviewed-by: Alan Donovan <adonovan@google.com>

These benchmarks show the effect of the combination of this change
and Rick's pending CL 6665. Code with interior pointers is helped
much more than code without, but even code without doesn't suffer
too badly.

benchmark                          old ns/op      new ns/op      delta
BenchmarkBinaryTree17              6989407768     6851728175     -1.97%
BenchmarkFannkuch11                4416250775     4405762558     -0.24%
BenchmarkFmtFprintfEmpty           134            130            -2.99%
BenchmarkFmtFprintfString          491            402            -18.13%
BenchmarkFmtFprintfInt             430            420            -2.33%
BenchmarkFmtFprintfIntInt          748            663            -11.36%
BenchmarkFmtFprintfPrefixedInt     602            534            -11.30%
BenchmarkFmtFprintfFloat           728            699            -3.98%
BenchmarkFmtManyArgs               2528           2507           -0.83%
BenchmarkGobDecode                 17448191       17749756       +1.73%
BenchmarkGobEncode                 14579824       14370183       -1.44%
BenchmarkGzip                      656489990      652669348      -0.58%
BenchmarkGunzip                    141254147      141099278      -0.11%
BenchmarkHTTPClientServer          94111          93738          -0.40%
BenchmarkJSONEncode                36305013       36696440       +1.08%
BenchmarkJSONDecode                124652000      128176454      +2.83%
BenchmarkMandelbrot200             6009333        5997093        -0.20%
BenchmarkGoParse                   7651583        7623494        -0.37%
BenchmarkRegexpMatchEasy0_32       213            213            +0.00%
BenchmarkRegexpMatchEasy0_1K       511            494            -3.33%
BenchmarkRegexpMatchEasy1_32       186            187            +0.54%
BenchmarkRegexpMatchEasy1_1K       1834           1827           -0.38%
BenchmarkRegexpMatchMedium_32      427            412            -3.51%
BenchmarkRegexpMatchMedium_1K      154841         153086         -1.13%
BenchmarkRegexpMatchHard_32        7473           7478           +0.07%
BenchmarkRegexpMatchHard_1K        233587         232272         -0.56%
BenchmarkRevcomp                   918797689      944528032      +2.80%
BenchmarkTemplate                  167665081      167773121      +0.06%
BenchmarkTimeParse                 631            636            +0.79%
BenchmarkTimeFormat                672            666            -0.89%

Change-Id: Ia923de3cdb3993b640fe0a02cbe2c7babc16f32c
Reviewed-on: https://go-review.googlesource.com/6782Reviewed-by: Rick Hudson <rlh@golang.org>
Reviewed-by: Austin Clements <austin@google.com>