Symbols in the object file currently refer to each other using symbol name
and version. Referring to the same symbol many times in an object file takes
up space and causes redundant map lookups. Instead write out a list of unique
symbol references and have symbols refer to each other using indexes into this
list.

Credit to Michael Hudson-Doyle for kicking this off.

Reduces pkg/linux_amd64 size by 30% from 61MB to 43MB

name       old s/op   new s/op   delta
LinkCmdGo  0.74 ± 3%  0.63 ± 4%  -15.22%  (p=0.000 n=20+20)
LinkJuju   6.38 ± 6%  5.73 ± 6%  -10.16%  (p=0.000 n=20+19)

Change-Id: I7e101a0c80b8e673a3ba688295e6f80ea04e1cfb
Reviewed-on: https://go-review.googlesource.com/20099Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

CL 14603 attempted to preserve the callee-save registers for
the darwin/arm runtime initialization routine, but I believe it
wasn't sufficient and resulted in the crash reported in issue

Saving and restoring the registers on the stack the same way
linux/arm does seems more obvious and fixes #14778, so do that.

Even though #14778 is not reproducible on darwin/arm64, I applied
a similar change there, and to linux/arm64 which obeys the same
calling convention.

Finally, this CL is a candidate for a 1.6 minor release for the same
reason CL 14603 was in a 1.5 minor release (as CL 16968). It is
small and only touches the iOS platforms and gomobile on darwin/arm
is currently useless without it.

Fixes #14778
Fixes #12590 (again)

Change-Id: I7401daf0bbd7c579a7e84761384a7b763651752a
Reviewed-on: https://go-review.googlesource.com/20621Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Move the C header style architecture constants to the per arch Main
methods.

Change-Id: Ie7ff39baa275ceaa6680e7d16441ca9f0aa12597
Reviewed-on: https://go-review.googlesource.com/20722Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Partial automatic cleanup driven by Dominik Honnef's unused tool.

As _lookup now only has one caller, merge it into the caller and remove
the conditional create logic.

Change-Id: I2ea354d9d4b32a19905271eca74725231b6d8a93
Reviewed-on: https://go-review.googlesource.com/20589
Run-TryBot: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

This is a band-aid, but it fixes the problem
until a deeper fix is in place.

Testing with genpkg -n 50000, I see:

Before:

      154.67 real       184.66 user         3.15 sys

After:

       61.82 real        96.99 user         2.17 sys


Fixes #14781.

Change-Id: I24c7822d60c289bdd6a18a7840b984954c95f7d4
Reviewed-on: https://go-review.googlesource.com/20696Reviewed-by: Robert Griesemer <gri@golang.org>

Treat the verb %X in the same special way as %q, %s and %x
are for arrays and slices with byte type elements.

Modify input for tests so the result of %x and %X is distinct.

Change-Id: I38d227755e98c7fad5e4adc2f603c6873aa910fd
Reviewed-on: https://go-review.googlesource.com/20516
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

Change-Id: I928f51a1fe4830a81d4f5d3eb572785e06a75b77
Reviewed-on: https://go-review.googlesource.com/20581Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Another step towards hooking up exported inlined function bodies.

Change-Id: Ib8094b03ac7970fee0e51b5826b5f8aa232e23fb
Reviewed-on: https://go-review.googlesource.com/20605Reviewed-by: Alan Donovan <adonovan@google.com>
Run-TryBot: Robert Griesemer <gri@golang.org>

Allows removing a bunch of unnecessary fields.

Passes toolstash/buildall.

Change-Id: Iec2492920e1c3ef352a9bf4296c74a55d9cc9ad6
Reviewed-on: https://go-review.googlesource.com/20677Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Workaround Go 1.4 compiler bugs.  See discussion at:
https://groups.google.com/d/msg/golang-dev/Ss7mCKsvk8w/Gsq7VYI0AwAJ

Change-Id: I842335fddffb67a6e21c000fe5bef258ea61c77a
Reviewed-on: https://go-review.googlesource.com/20690Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Change-Id: I93e73f16474b4b31f7097af2f9479822dfc34c5c
Reviewed-on: https://go-review.googlesource.com/20678Reviewed-by: Adam Langley <agl@golang.org>

Currently, the only use for this is on the Left side of OKEY nodes
within struct literals.  esc and fmt only care so they can recognize
that the ONAME nodes are actually field names, which need special
handling.

sinit additionally needs to know the field's offset within the struct,
which we can provide via Xoffset.

Passes toolstash/buildall.

Change-Id: I362d965e161f4d80fcd9c9bae0dfacc657dc0b29
Reviewed-on: https://go-review.googlesource.com/20676Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Passes toolstash -cmp.

Change-Id: Id16009ef3ef1173eafe0f0c578dbf325b61aab3c
Reviewed-on: https://go-review.googlesource.com/20674
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Dave Cheney <dave@cheney.net>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Switch TSTRUCT and TINTER to use Fields instead of Type, which wrings
out the remaining few direct uses of the latter.

Preparation for converting fields to use a separate "Field" type.

Passes toolstash/buildall.

Change-Id: I5a2ea7e159d0dde1be2c9afafc10a8f739d95743
Reviewed-on: https://go-review.googlesource.com/20675
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>

Passes toolstash -cmp.

Change-Id: Iaa0d78c2552efb29e67f6c99c7287f8566027add
Reviewed-on: https://go-review.googlesource.com/20673Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Follow-up to CL 20645.

Passes toolstash -cmp.

Change-Id: Idc63c41b2be2d52e3a6ac59b3a12eb41aa2efbed
Reviewed-on: https://go-review.googlesource.com/20670Reviewed-by: Ian Lance Taylor <iant@golang.org>

Change-Id: I434f881c10dec41a802641db8873abf1353beba2
Reviewed-on: https://go-review.googlesource.com/20671
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

String symbols' names used to appear in the final binary.
Using a string's contents as it's symbol's name
was a thus a bad idea if the string's name was long.
Recent improvements by crawshaw have changed that.

Instead of placing long strings behind opaque names
in local packages, place them in the global string
package and make them content-addressable.
Symbol names still occur in the object files,
so use a hash to avoid needless length there.

Reduces the size of cmd/go by 30k.

Change-Id: Ifdbbaf47bf44352418c90ddd903d5106e48db4f1
Reviewed-on: https://go-review.googlesource.com/20524
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>

decompose-builtin pass requires an opt pass, but -N disables
late-opt, the only opt pass (out of two) that happens
after decompose-builtin.  This CL enables both 'opt' and 'late opt'
passes. The extra compile time for 'late opt' in negligible
since most rewrites were already done in the first 'opt'
(also measured before). We should put some effort in splitting the
generic rules into required and optional.

Also update generic.rules comments about lowering
of StringMake and SliceMake.

Tested with GO_GCFLAGS=-N ./all.bash

Change-Id: I92999681aaa02587b6dc6e32ce997a91f1fc9499
Reviewed-on: https://go-review.googlesource.com/20682
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Parts of the SSA compiler in package gc contain amd64-specific code,
most notably Prog generation. Move this code into package amd64, so that
other architectures can be added more easily.

In package gc, this change is just moving code. There are no functional
changes or even any larger structural changes beyond changing function
names (mostly for export).

In the cmd/compile/internal/ssa/gen tool, more information is included
in arch to remove the AMD64-specific behavior in the main portion of the
tool. The generated opGen.go is identical.

Change-Id: I8eb37c6e6df6de1b65fa7dab6f3bc32c29daf643
Reviewed-on: https://go-review.googlesource.com/20609Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

In particular, write down the rules for stack ownership because the
details of this are about to get very important with concurrent stack
shrinking. (Interestingly, the details don't actually change, but
anything that's currently skating on thin ice is likely to fall
through.)

Fox #12967.

Change-Id: I561e2610e864295e9faba07717a934aabefcaab9
Reviewed-on: https://go-review.googlesource.com/20034Reviewed-by: Rick Hudson <rlh@golang.org>

Currently copystack adjusts pointers in the old stack and then copies
the adjusted stack to the new stack. In addition to being generally
confusing, this is going to make concurrent stack shrinking harder.

Switch this around so that we first copy the stack and then adjust
pointers on the new stack (never writing to the old stack).

This reprises CL 15996, but takes a different and simpler approach. CL
15996 still walked the old stack while adjusting pointers on the new
stack. In this CL, we adjust auxiliary structures before walking the
stack, so we can just walk the new stack.

For #12967.

Change-Id: I94fa86f823ba9ee478e73b2ba509eed3361c43df
Reviewed-on: https://go-review.googlesource.com/20033Reviewed-by: Rick Hudson <rlh@golang.org>

In particular, document that *sel is on the stack no matter what.

Change-Id: I1c264215e026c27721b13eedae73ec845066cdec
Reviewed-on: https://go-review.googlesource.com/20032Reviewed-by: Rick Hudson <rlh@golang.org>

Fixes #14772

Change-Id: I32f2b6b74de28be406b1306364bc07620a453962
Reviewed-on: https://go-review.googlesource.com/20680Reviewed-by: David du Colombier <0intro@gmail.com>
Reviewed-by: Minux Ma <minux@golang.org>
Run-TryBot: Minux Ma <minux@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Line numbers are always int32, so the Warnl function should take the
line number as an int32 as well.  This matches gc.Warnl and removes
a cast every place it's used.

Change-Id: I5d6201e640d52ec390eb7174f8fd8c438d4efe58
Reviewed-on: https://go-review.googlesource.com/20662
Run-TryBot: Todd Neal <todd@tneal.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

Just recognize "DATA" as a special pseudo op word in the assembler
directly.

Change-Id: I508e111fd71f561efa600ad69567a7089a57adb2
Reviewed-on: https://go-review.googlesource.com/20648
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

Updates #14786.

Change-Id: I5fe889886f772167386cd10390ac50abc1383937
Reviewed-on: https://go-review.googlesource.com/20607
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

The only remaining place that generated ADATA
Prog was the assembler. Stop, and delete some
now-dead code.

Passes toolstash -cmp.

Change-Id: I26578ff1b4868e98562b44f69d909c083e96f8d5
Reviewed-on: https://go-review.googlesource.com/20646Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Instead of generating ADATA instructions for
static data, write that static data directly
into the linker sym.
This is considerably more efficient.
The assembler still generates
ADATA instructions, so the ADATA machinery
cannot be dismantled yet. (Future work.)
Skipping ADATA has a significant impact
compiling the unicode package, which has lots
of static data.

name     old time/op    new time/op    delta
Unicode     227ms ±10%     192ms ± 4%  -15.61%  (p=0.000 n=29+30)

name     old alloc/op   new alloc/op   delta
Unicode    51.0MB ± 0%    45.8MB ± 0%  -10.29%  (p=0.000 n=30+30)

name     old allocs/op  new allocs/op  delta
Unicode      610k ± 0%      578k ± 0%   -5.29%  (p=0.000 n=30+30)

This does not pass toolstash -cmp, because
this changes the order in which some relocations
get added, and thus it changes the output from
the compiler. It is not worth the execution time
to sort the relocs in the normal case.

However, compiling with -S -v generates identical
output if (1) you suppress printing of ADATA progs
in flushplist and (2) you suppress printing of
cpu timing. It is reasonable to suppress printing
the ADATA progs, since the data itself is dumped
later. I am therefore fairly confident that all
changes are superficial and non-functional.

Fixes #14786, although there's more to do
in general.

Change-Id: I8dfabe7b423b31a30e516cfdf005b62a2e9ccd82
Reviewed-on: https://go-review.googlesource.com/20645Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

And fix the wrong comment.

Initially found this because the comment was wrong about the possible
values. Then noticed that there doesn't seem to be any reason to use
uintptr over SelectDir.

Change-Id: I4f9f9640e49d89e558ed00bd99e57dab890785f5
Reviewed-on: https://go-review.googlesource.com/20655Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Only compute the number of maximum allowed elements per slice once.
Special case newcap computation for slices with byte sized elements.

name              old time/op  new time/op  delta
GrowSliceBytes-2  61.1ns ± 1%  43.4ns ± 1%  -29.00%  (p=0.000 n=20+20)
GrowSliceInts-2   85.9ns ± 1%  75.7ns ± 1%  -11.80%  (p=0.000 n=20+20)

Change-Id: I5d9c0d5987cdd108ac29dc32e31912dcefa2324d
Reviewed-on: https://go-review.googlesource.com/20653Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

It was failing like "unknown groupid ᎈ|" instead of "unknown groupid
5000" due to the conversion from int to string.

Updates #14806

Change-Id: I83e4b478ff628ad4053573a9f32b3fadce22e847
Reviewed-on: https://go-review.googlesource.com/20642Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>

Fixes #11419.

Change-Id: I7935a253e3e96191a33f5041bab203ecc5f0c976
Reviewed-on: https://go-review.googlesource.com/20647Reviewed-by: Keith Randall <khr@golang.org>

* Shaves about 10k from pkg/tools/linux_amd64.
* Was suggested by drchase before
* Found by looking at ssa output of #14758

Change-Id: If2c4ddf3b2603d4dfd8fb4d9199b9a3dcb05b17d
Reviewed-on: https://go-review.googlesource.com/20570Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Simplify function signature.
Remove unused Ctxt field Enforce_data_order.

Passes toolstash -cmp.

Change-Id: I5caa270ca9ae725708fe415b2c978b5f40780255
Reviewed-on: https://go-review.googlesource.com/20644
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Passes toolstash -cmp.

Change-Id: Ib8c76081956e1d4eecef16b82bc8d527d7849d7e
Reviewed-on: https://go-review.googlesource.com/20643
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

pprof crashed when running with:

     go tool pprof %INVALID

Change-Id: I47c2a4da7273e3a97a833f320a650b8c6b59d6b9
Reviewed-on: https://go-review.googlesource.com/20632Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

This makes the output of compiling with -S more
stable in the face of unimportant variation in the
order in which relocs are generated.
It is also more pleasant to read the relocs when
they are sorted.

Also, do some minor cleanup.

For #14786

Change-Id: Id92020b13fd21777dfb5b29c2722c3b2eb27001b
Reviewed-on: https://go-review.googlesource.com/20641Reviewed-by: Matthew Dempsky <mdempsky@google.com>

Shrinks gc.Type and gc.Func slightly.

Passes "GOEXPERIMENT=fieldtrack ./all.bash" and "go test -a
-toolexec='toolstash -cmp' -ldflags=-k=rsc.io/tmp/fieldtrack.tracked
rsc.io/tmp/fieldtrack".

Change-Id: I785fe8a18eb830d9867d34247e4cd41a6a7921d4
Reviewed-on: https://go-review.googlesource.com/20557
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

Split the auxFloat type into 32/64 bit versions and perform checking for
exactly representable float32 values.  Perform const folding on
float32/64.  Comment out some const negation rules that the frontend
already performs.

Change-Id: Ib3f8d59fa8b30e50fe0267786cfb3c50a06169d2
Reviewed-on: https://go-review.googlesource.com/20568
Run-TryBot: Todd Neal <todd@tneal.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>