Ignore symbols that aren't text, data, or bss since they cause
problems when dissassembling instructions with small immediate
values.

Before:
        build.go:142    0x10ee  83ec50      SUBL $text/template/parse.autotmp_1293(SB), SP

After:
        build.go:142    0x10ee  83ec50      SUBL $0x50, SP

Fixes #7947.

LGTM=rsc
R=rsc, 0intro
CC=golang-codereviews
https://golang.org/cl/93520045

Noted by gri in CL 100660044 review but I missed them.

TBR=gri
CC=golang-codereviews
https://golang.org/cl/97570049

Add larger comment explaining testing methodology,
and derive tests arithmetically.

(These tests are checking rounding again; the derived
tests they replace were checking exact values.)

LGTM=r, gri
R=gri, r
CC=golang-codereviews
https://golang.org/cl/100660044

Passes the expanded test in CL 100660044,
which gives me some confidence that it
might be right.

(The old code failed by not considering all the
low bits.)

LGTM=r
R=golang-codereviews, r, bradfitz
CC=golang-codereviews, iant, khr
https://golang.org/cl/99410051

Rewrite formatFloat to be much simpler and clearer and
avoid the tricky interaction with padding.
The issue refers to complex but the problem is just floating-point.
The new tests added were incorrectly formatted before this fix.
Fixes #8064.

LGTM=jscrockett01, rsc
R=rsc, jscrockett01
CC=golang-codereviews
https://golang.org/cl/99420048

Fixes #8062.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/91610046

Fixes #7983.

LGTM=crawshaw
R=golang-codereviews, crawshaw
CC=golang-codereviews, rsc
https://golang.org/cl/96540044

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/95480045

These constants pass go/types constant conversions as well.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/91590047

Fixes #8061.

LGTM=crawshaw
R=golang-codereviews, crawshaw
CC=golang-codereviews
https://golang.org/cl/93520046

Patch from http://gnats.NetBSD.org/48811.

LGTM=iant
R=golang-codereviews, minux.ma, iant
CC=golang-codereviews, tk
https://golang.org/cl/94670047

Fixes #8032.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/95580043

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/100660043

The spec did not specify the order in which
init() functions are called. Specify that
they are called in source order since we have
now also specified the initialization order
of independent variables.

While technically a language change, no
existing code could have relied on this,
so this should not break anything.

Per suggestion from rsc.

LGTM=r, iant
R=rsc, iant, r, ken
CC=golang-codereviews
https://golang.org/cl/98420046

Fixes #8051

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/95560046

- split description of package initialization and
  program execution
- better grouping of concerns in section on package
  initialization
- more explicit definition of what constitues a
  dependency
- removed language about constant dependencies -
  they are computed at compile-time and not
  initialized at run-time
- clarified that independent variables are initialized
  in declaration order (rather than reference order)

Note that the last clarification is what distinguishes
gc and gccgo at the moment: gc uses reference order
(i.e., order in which variables are referenced in
initialization expressions), while gccgo uses declaration
order for independent variables.

Not a language change. But adopting this CL will
clarify what constitutes a dependency.

Fixes #6703.

LGTM=adonovan, r, iant, rsc
R=r, rsc, iant, ken, adonovan
CC=golang-codereviews
https://golang.org/cl/99020043

LGTM=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/99420045

LGTM=minux.ma
R=adg, minux.ma
CC=golang-codereviews
https://golang.org/cl/95540045

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/93470043

Fixes #7701. (again, differently)

LGTM=rsc
R=iant, rsc
CC=golang-codereviews
https://golang.org/cl/94560043

TBR=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/98480043

This idea was rejected in CL 5731059. We should fix the
runtime docs instead.

««« original CL description
cmd/dist: reflect local changes to tree in goversion

runtime.Version() requires a trailing "+" when
tree had local modifications at time of build.

Fixes #7701

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/84040045

»»»

LGTM=rsc, mra
R=iant, rsc, mra
CC=golang-codereviews
https://golang.org/cl/100520043

- Don't export Prog structure.
- Remove ProgHeader and ExecTable structures.
- Add Magic, Bss and Entry fields in FileHeader.
- Replace ?_MAGIC variables with constants.
- Ignore final EOF from ReadAt.
- Improve documentation.

Fixes #7989.

LGTM=rsc
R=rsc, bradfitz
CC=golang-codereviews
https://golang.org/cl/91400044

Explain which files the go command looks at, and what they represent.
Fixes #6348.

LGTM=rsc
R=rsc, minux.ma
CC=golang-codereviews
https://golang.org/cl/96480043

Fixes #7958.

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/91590044

Add nacl.bash, the NaCl version of all.bash.
It's a separate script because it builds a variant of package syscall
with a large zip file embedded in it, containing all the input files
needed for tests.

Disable various tests new since the last round, mostly the ones using os/exec.

Fixes #7945.

LGTM=dave
R=golang-codereviews, remyoudompheng, dave, bradfitz
CC=golang-codereviews
https://golang.org/cl/100590044

I don't know when the bug was fixed, but empirically it was.
Make sure it stays fixed by adding a test.

Fixes #7884.

LGTM=adg
R=golang-codereviews, adg
CC=golang-codereviews
https://golang.org/cl/93500043

Fixes #7050.

LGTM=crawshaw, r
R=golang-codereviews, crawshaw, r
CC=golang-codereviews
https://golang.org/cl/91590043

Apparently all the __DWARF sections need addresses
even though they are marked as "do not load from disk".
Continue the address numbering from the data segment.

With this change:

g% lldb helloworld
Current executable set to 'helloworld' (x86_64).
(lldb) b main.main
Breakpoint 1: where = helloworld`main.main + 25 at helloworld.go:12, address = 0x0000000000002019
(lldb) r
Process 68509 launched: '/Users/rsc/g/go/src/cmd/6l/helloworld' (x86_64)
1 location added to breakpoint 1
(lldb)
[KProcess 68509 stopped
* thread #1: tid = 0x8b7a27, 0x0000000000002019 helloworld`main.main + 25 at helloworld.go:12, stop reason = breakpoint 1.2
    frame #0: 0x0000000000002019 helloworld`main.main + 25 at helloworld.go:12
   9   	package main
   10
   11  	func main() {
-> 12  		print("hello, world\n")
   13  	}
(lldb) bt
* thread #1: tid = 0x8b7a27, 0x0000000000002019 helloworld`main.main + 25 at helloworld.go:12, stop reason = breakpoint 1.2
  * frame #0: 0x0000000000002019 helloworld`main.main + 25 at helloworld.go:12
(lldb) disas
helloworld`main.main at helloworld.go:11:
   0x2000:  movq   %gs:0x8a0, %rcx
   0x2009:  cmpq   (%rcx), %rsp
   0x200c:  ja     0x2015                    ; main.main + 21 at helloworld.go:11
   0x200e:  callq  0x20da0                   ; runtime.morestack00_noctxt at atomic_amd64x.c:28
   0x2013:  jmp    0x2000                    ; main.main at helloworld.go:11
   0x2015:  subq   $0x10, %rsp
-> 0x2019:  leaq   0x2c2e0, %rbx
   0x2021:  leaq   (%rsp), %rbp
   0x2025:  movq   %rbp, %rdi
   0x2028:  movq   %rbx, %rsi
   0x202b:  movsq
   0x202d:  movsq
   0x202f:  callq  0x10300                   ; runtime.printstring at compiler.go:1
   0x2034:  addq   $0x10, %rsp
   0x2038:  ret
   0x2039:  addb   %al, (%rax)
   0x203b:  addb   %al, (%rax)
   0x203d:  addb   %al, (%rax)
(lldb) quit
Quitting LLDB will kill one or more processes. Do you really want to proceed: [Y/n] y
g%

Fixes #7070.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/93510043

Fixes #7835.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/94670044

Update #8030

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/94680043

Update #4714

LGTM=iant, minux.ma, rsc
R=rsc, iant, r, minux.ma
CC=golang-codereviews
https://golang.org/cl/100390043

The USEFIELD instructions no longer make it to the linker,
so we have to do something else to pin the references
they were pinning. Emit a 0-length relocation of type R_USEFIELD.

Fixes #7486.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews, r
https://golang.org/cl/95530043

The move from 4kB to 8kB in Go 1.2 was to eliminate many stack split hot spots.

The move back to 4kB was predicated on copying stacks eliminating
the potential for hot spots.

Unfortunately, the fact that stacks do not copy 100% of the time means
that hot spots can still happen under the right conditions, and the slowdown
is worse now than it was in Go 1.2. There is a real program in issue 8030 that
sees about a 30x slowdown: it has a reflect call near the top of the stack
which inhibits any stack copying on that segment.

Go back to 8kB until stack copying can be used 100% of the time.

Fixes #8030.

LGTM=khr, dave, iant
R=iant, khr, r, bradfitz, dave
CC=golang-codereviews
https://golang.org/cl/92540043

The float32 const conversion used to round to float64
and then use the hardware to round to float32.
Even though there was a range check before this
conversion, the double rounding introduced inaccuracy:
the round to float64 might round the value further away
from the float32 range, reaching a float64 value that
could not actually be rounded to float32. The hardware
appears to give us 0 in that case, but it is probably undefined.
Double rounding also meant that the wrong value might
be used for certain border cases.

Do the rounding the float32 ourselves, just as we already
did the rounding to float64. This makes the conversion
precise and also makes the conversion match the range check.

Finally, add some code to print very large (bigger than float64)
floating point constants in decimal floating point notation instead
of falling back to the precise but human-unreadable binary floating
point notation.

Fixes #8015.

LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews, r
https://golang.org/cl/100580044

Update #7980
This CL make the linker abort for the example program. For Go 1.4,
we need to find a general way to handle large memory model programs.

LGTM=dave, josharian, iant
R=iant, dave, josharian
CC=golang-codereviews
https://golang.org/cl/91500046

Fixes #7445.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/94640043

The temporary-introducing pass was not recursing
into the argumnt of a receive operation.

Fixes #8011.

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews, iant, khr
https://golang.org/cl/91540043

Fixes #7256

LGTM=r
R=golang-codereviews, r
CC=golang-codereviews, rsc
https://golang.org/cl/97590043

This is the main point of confusion and the emphasis of
a recent Gophercon talk.

Fixes #5886. (mostly fixed in previous commits)

LGTM=r
R=r
CC=golang-codereviews
https://golang.org/cl/100560043