Shenghou Ma [Tue, 10 Dec 2013 04:25:13 +0000 (23:25 -0500)]
os: clarify docs for Rename.
Three changes:
1. mention "move" to clarify things up.
2. use {old,new}path instead of {old,new}name, which makes it clear what
relative path would do here.
3. mention "OS-specific restrictions might apply".
Fixes #6887.
R=golang-dev, alex.brainman, iant, r
CC=golang-dev
https://golang.org/cl/36930044
David du Colombier [Mon, 9 Dec 2013 23:47:22 +0000 (18:47 -0500)]
cmd/8c, cmd/8g, cmd/8l: fix Plan 9 warnings
warning: src/cmd/8c/list.c:124 format mismatch d VLONG, arg 3
warning: src/cmd/8c/list.c:134 format mismatch d VLONG, arg 3
warning: src/cmd/8c/list.c:142 format mismatch d VLONG, arg 3
warning: src/cmd/8c/list.c:152 format mismatch d VLONG, arg 3
warning: src/cmd/8c/list.c:156 format mismatch d VLONG, arg 4
warning: src/cmd/8c/list.c:160 format mismatch d VLONG, arg 4
warning: src/cmd/8c/list.c:165 format mismatch d VLONG, arg 4
warning: src/cmd/8c/list.c:167 format mismatch d VLONG, arg 3
warning: src/cmd/8c/list.c:172 format mismatch d VLONG, arg 4
warning: src/cmd/8c/list.c:174 format mismatch d VLONG, arg 3
warning: src/cmd/8c/list.c:178 format mismatch d VLONG, arg 3
warning: src/cmd/8c/list.c:184 format mismatch d VLONG, arg 3
warning: src/cmd/8g/list.c:91 format mismatch d VLONG, arg 4
warning: src/cmd/8g/list.c:100 format mismatch d VLONG, arg 4
warning: src/cmd/8g/list.c:114 format mismatch d VLONG, arg 5
warning: src/cmd/8g/list.c:118 format mismatch d VLONG, arg 5
warning: src/cmd/8g/list.c:122 format mismatch d VLONG, arg 5
warning: src/cmd/8g/list.c:126 format mismatch d VLONG, arg 5
warning: src/cmd/8g/list.c:136 format mismatch d VLONG, arg 4
warning: src/cmd/8l/list.c:107 format mismatch d VLONG, arg 4
warning: src/cmd/8l/list.c:125 format mismatch ux VLONG, arg 4
warning: src/cmd/8l/list.c:128 format mismatch ux VLONG, arg 4
warning: src/cmd/8l/list.c:130 format mismatch d VLONG, arg 4
warning: src/cmd/8l/list.c:134 format mismatch d VLONG, arg 5
warning: src/cmd/8l/list.c:138 format mismatch d VLONG, arg 6
warning: src/cmd/8l/list.c:143 format mismatch d VLONG, arg 5
warning: src/cmd/8l/list.c:148 format mismatch d VLONG, arg 5
warning: src/cmd/8l/list.c:150 format mismatch d VLONG, arg 4
warning: src/cmd/8l/list.c:154 format mismatch d VLONG, arg 4
warning: src/cmd/8l/list.c:158 format mismatch d VLONG, arg 4
warning: src/cmd/8l/obj.c:132 format mismatch ux VLONG, arg 2
Anthony Martin [Mon, 9 Dec 2013 23:41:48 +0000 (18:41 -0500)]
runtime: do not use memmove in the Plan 9 signal handler
Fixes a regression introduced in revision 4cb93e2900d0.
That revision changed runtime·memmove to use SSE MOVOU
instructions for sizes between 17 and 256 bytes. We were
using memmove to save a copy of the note string during
the note handler. The Plan 9 kernel does not allow the
use of floating point in note handlers (which includes
MOVOU since it touches the XMM registers).
Arguably, runtime·memmove should not be using MOVOU when
GO386=387 but that wouldn't help us on amd64. It's very
important that we guard against any future changes so we
use a simple copy loop instead.
This change is extracted from CL 9796043 (since that CL
is still being ironed out).
Carl Shapiro [Mon, 9 Dec 2013 22:45:10 +0000 (14:45 -0800)]
cmd/gc, runtime: correct a misnomer regarding dead value maps
The funcdata symbol incorrectly named the dead value map the
dead pointer map. The dead value map identifies all dead
values, including pointers and non-pointers, in a stack frame.
The purpose of this map is to allow the runtime to poison
locations of dead data to catch lost invariants.
Russ Cox [Mon, 9 Dec 2013 15:33:27 +0000 (10:33 -0500)]
cmd/dist, cmd/go: pass -fmessage-length=0 when using clang
That option turns off word wrapping of individual
error messages generated by clang. The wrapping
makes the errors harder to read and conflicts with the
idea of a terminal window that can be resized.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/35810043
Russ Cox [Mon, 9 Dec 2013 03:49:37 +0000 (22:49 -0500)]
liblink: create new library based on linker code
There is an enormous amount of code moving around in this CL,
but the code is the same, and it is invoked in the same ways.
This CL is preparation for the new linker structure, not the new
structure itself.
The new library's definition is in include/link.h.
The main change is the use of a Link structure to hold all the
linker-relevant state, replacing the smattering of global variables.
The Link structure should both make it clearer which state must
be carried around and make it possible to parallelize more easily
later.
The main body of the linker has moved into the architecture-independent
cmd/ld directory. That includes the list of known header types, so the
distinction between Hplan9x32 and Hplan9x64 is removed (no other
header type distinguished 32- and 64-bit formats), and code for unused
formats such as ipaq kernels has been deleted.
The code being deleted from 5l, 6l, and 8l reappears in liblink or in ld.
Because multiple files are being merged in the liblink directory,
it is not possible to show the diffs nicely in hg.
The Prog and Addr structures have been unified into an
architecture-independent form and moved to link.h, where they will
be shared by all tools: the assemblers, the compilers, and the linkers.
The unification makes it possible to write architecture-independent
traversal of Prog lists, among other benefits.
The Sym structures cannot be unified: they are too fundamentally
different between the linker and the compilers. Instead, liblink defines
an LSym - a linker Sym - to be used in the Prog and Addr structures,
and the linker now refers exclusively to LSyms. The compilers will
keep using their own syms but will fill out the corresponding LSyms in
the Prog and Addr structures.
Although code from 5l, 6l, and 8l is now in a single library, the
code has been arranged so that only one architecture needs to
be linked into a particular program: 5l will not contain the code
needed for x86 instruction layout, for example.
The object file writing code in liblink/obj.c is from cmd/gc/obj.c.
Preparation for golang.org/s/go13linker work.
This CL does not build by itself. It depends on 35740044
and will be submitted at the same time.
Russ Cox [Mon, 9 Dec 2013 03:48:11 +0000 (22:48 -0500)]
cmd/dist: add liblink build information
In addition to adding the library, change the way the anames array is created.
Previously, it was written to src/cmd/6l/enam.c (and similarly for 5l and 8l)
and each of the other tools (6g, 6c, 6a) compiled the 6l/enam.c file in addition
to their own sources.
Now that there is a library shared by all these programs, move the anames
array into that library. To eliminate name conflicts, name the array after
the architecture letter: anames5, anames6, anames8.
First step to linker cleanup (golang.org/s/go13linker).
This CL does not build by itself. It depends on the CLs introducing
liblink and changing commands to use it.
Carl Shapiro [Fri, 6 Dec 2013 22:40:45 +0000 (14:40 -0800)]
runtime: add GODEBUG option for an electric fence like heap mode
When enabled this new debugging mode will allocate objects on
their own page and never recycle memory addresses. This is an
essential tool to root cause a broad class of heap corruption.
This change allows the garbage collector to examine stack
slots that are determined as live and containing a pointer
value by the garbage collector. This results in a mean
reduction of 65% in the number of stack slots scanned during
an invocation of "GOGC=1 all.bash".
Unfortunately, this does not yet allow garbage collection to
be precise for the stack slots computed as live. Pointers
confound the determination of what definitions reach a given
instruction. In general, this problem is not solvable without
runtime cost but some advanced cooperation from the compiler
might mitigate common cases.
Carl Shapiro [Tue, 3 Dec 2013 22:12:55 +0000 (14:12 -0800)]
runtime: move stack scanning into the parallel mark phase
This change reduces the cost of the stack scanning by frames.
It moves the stack scanning from the serial root enumeration
phase to the parallel tracing phase. The output that follows
are timings for the issue 6482 benchmark
The remaining performance disparity is due to inefficiencies
in gentraceback and its callees. The effect was isolated by
using a parallel stack scan where scanstack was modified to do
a conservative scan of the stack segments without gentraceback
followed by a call of gentrackback with a no-op callback.
The output that follows are the top-10 most frequent tops of
stacks as determined by the Linux perf record facility.
Keith Randall [Tue, 3 Dec 2013 02:03:25 +0000 (18:03 -0800)]
runtime: fix race detector when map keys/values are passed by pointer.
Now that the map implementation is reading the keys and values from
arbitrary memory (instead of from stack slots), it needs to tell the
race detector when it does so.
Fixes #6875.
R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/36360043
Keith Randall [Mon, 2 Dec 2013 21:36:50 +0000 (13:36 -0800)]
reflect: prevent the callXX routines from calling makeFuncStub
and methodValueCall directly. Instead, we inline their behavior
inside of reflect.call.
This change is required because otherwise we have a situation where
reflect.callXX calls makeFuncStub, neither of which knows the
layout of the args passed between them. That's bad for
precise gc & stack copying.
Keith Randall [Mon, 2 Dec 2013 21:05:04 +0000 (13:05 -0800)]
runtime: pass key/value to map accessors by reference, not by value.
This change is part of the plan to get rid of all vararg C calls
which are a pain for getting exact stack scanning.
We allocate a chunk of zero memory to return a pointer to when a
map access doesn't find the key. This is simpler than returning nil
and fixing things up in the caller. Linker magic allocates a single
zero memory area that is shared by all (non-reflect-generated) map
types.
Passing things by reference gets rid of some copies, so it speeds
up code with big keys/values.
benchmark old ns/op new ns/op delta
BenchmarkBigKeyMap 34 31 -8.48%
BenchmarkBigValMap 37 30 -18.62%
BenchmarkSmallKeyMap 26 23 -11.28%
Andrew Gerrand [Wed, 20 Nov 2013 20:55:29 +0000 (07:55 +1100)]
doc: update installation instructions
Clarify that GOROOT should only be set when using a custom install path.
Remove NetBSD from binary install page (we don't provide binaries).
Remove "What's next" links from installation instructions.
Emphasize "How to Write Go Code" page.
Fixes #6613.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/28700043
Russ Cox [Thu, 7 Nov 2013 20:24:51 +0000 (15:24 -0500)]
cmd/cgo: fix handling of array of pointers when using clang
Clang does not record the "size" field for pointer types,
so we must insert the size ourselves. We were already
doing this, but only for the case of pointer types.
For an array of pointer types, the setting of the size for
the nested pointer type was happening after the computation
of the size of the array type, meaning that the array type
was always computed as 0 bytes. Delay the size computation.
This bug happens on all Clang systems, not just FreeBSD.
Our test checked that cgo wrote something, not that it was correct.
FreeBSD's default clang rejects array[0] as a C struct field,
so it noticed the incorrect sizes. But the sizes were incorrect
everywhere.
Update testcdefs to check the output has the right semantics.
Russ Cox [Thu, 31 Oct 2013 18:15:55 +0000 (18:15 +0000)]
cmd/5l, runtime: fix divide for profiling tracebacks on ARM
Two bugs:
1. The first iteration of the traceback always uses LR when provided,
which it is (only) during a profiling signal, but in fact LR is correct
only if the stack frame has not been allocated yet. Otherwise an
intervening call may have changed LR, and the saved copy in the stack
frame should be used. Fix in traceback_arm.c.
2. The division runtime call adds 8 bytes to the stack. In order to
keep the traceback routines happy, it must copy the saved LR into
the new 0(SP). Change
SUB $8, SP
into
MOVW 0(SP), R11 // r11 is temporary, for use by linker
MOVW.W R11, -8(SP)
to update SP and 0(SP) atomically, so that the traceback always
sees a saved LR at 0(SP).
Fixes #6681.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/19910044
The CL causes misc/cgo/test to fail randomly.
I suspect that the problem is the use of a division instruction
in usleep, which can be called while trying to acquire an m
and therefore cannot store the denominator in m.
The solution to that would be to rewrite the code to use a
magic multiply instead of a divide, but now we're getting
pretty far off the original code.
Go back to the original in preparation for a different,
less efficient but simpler fix.
««« original CL description
cmd/5l, runtime: make ARM integer division profiler-friendly
The implementation of division constructed non-standard
stack frames that could not be handled by the traceback
routines.
CL 13239052 left the frames non-standard but fixed them
for the specific case of a divide-by-zero panic.
A profiling signal can arrive at any time, so that fix
is not sufficient.
Change the division to store the extra argument in the M struct
instead of in a new stack slot. That keeps the frames bog standard
at all times.
Also fix a related bug in the traceback code: when starting
a traceback, the LR register should be ignored if the current
function has already allocated its stack frame and saved the
original LR on the stack. The stack copy should be used, as the
LR register may have been modified.
Combined, these make the torture test from issue 6681 pass.
Russ Cox [Wed, 30 Oct 2013 18:50:34 +0000 (18:50 +0000)]
cmd/5l, runtime: make ARM integer division profiler-friendly
The implementation of division constructed non-standard
stack frames that could not be handled by the traceback
routines.
CL 13239052 left the frames non-standard but fixed them
for the specific case of a divide-by-zero panic.
A profiling signal can arrive at any time, so that fix
is not sufficient.
Change the division to store the extra argument in the M struct
instead of in a new stack slot. That keeps the frames bog standard
at all times.
Also fix a related bug in the traceback code: when starting
a traceback, the LR register should be ignored if the current
function has already allocated its stack frame and saved the
original LR on the stack. The stack copy should be used, as the
LR register may have been modified.
Combined, these make the torture test from issue 6681 pass.
Russ Cox [Wed, 30 Oct 2013 14:24:42 +0000 (10:24 -0400)]
cmd/cgo: accept extra leading _ on __cgodebug_data for all object formats
The current Windows build breakage appears to be because
the Windows code should be looking for __cgodebug_data
not ___cgodebug_data. Dodge the question everywhere by
accepting both.
Russ Cox [Tue, 29 Oct 2013 21:11:51 +0000 (17:11 -0400)]
time: correct path to time zone zip file on Unix
Most Unix systems have their own time zone data,
so we almost never get far enough in the list to
discover that we cannot fall back to the zip file.
Adjust testing to exercise the final fallback.
Plan 9 and Windows were already correct
(and are the main users of the zip file).
Russ Cox [Tue, 29 Oct 2013 15:50:40 +0000 (11:50 -0400)]
os: do not return Lstat errors from Readdir
This CL restores the Go 1.1.2 semantics for os.File's Readdir method.
The code in Go 1.1.2 was rewritten mainly because it looked buggy.
This new version attempts to be clearer but still provide the 1.1.2 results.
The important diff is not this CL's version against tip but this CL's version
against Go 1.1.2.
Go 1.1.2:
names, err := f.Readdirnames(n)
fi = make([]FileInfo, len(names))
for i, filename := range names {
fip, err := Lstat(dirname + filename)
if err == nil {
fi[i] = fip
} else {
fi[i] = &fileStat{name: filename}
}
}
return fi, err
This CL:
names, err := f.Readdirnames(n)
fi = make([]FileInfo, len(names))
for i, filename := range names {
fip, lerr := lstat(dirname + filename)
if lerr != nil {
fi[i] = &fileStat{name: filename}
continue
}
fi[i] = fip
}
return fi, err
The changes from Go 1.1.2 are stylistic, not semantic:
1. Use lstat instead of Lstat, for testing (done before this CL).
2. Make error handling in loop body look more like an error case.
3. Use separate error variable name in loop body, to be clear
we are not trying to influence the final return result.