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.
Russ Cox [Tue, 29 Oct 2013 14:36:51 +0000 (10:36 -0400)]
debug/dwarf: add DWARF 4 form constants
Some versions of clang generate DWARF 4-format attributes
even when using -gdwarf-2. We don't care much about the
values, but we do need to be able to parse past them.
This fixes a bug in Go 1.2 rc2 reported via private mail using
a near-tip version of clang.
Russ Cox [Tue, 29 Oct 2013 02:21:26 +0000 (22:21 -0400)]
cmd/cgo: stop using -fno-eliminate-unused-debug-types
This flag was added in January 2010, in CL 181102, to fix issue 497.
(Numbers were just shorter back then.) The fix was for OS X machines
and the llvm-gcc frontend.
In July 2011 we had to change the way we get enum values, because
there were no flags available to force Xcode's llvm-gcc to include the
enum names and values in DWARF debug output.
We now use clang, not llvm-gcc, on OS X machines.
Earlier versions of clang printed a warning about not knowing the flag.
Newer versions of clang now make that an error.
That is:
- The flag was added for OS X machines.
- The flag is no longer necessary on OS X machines.
- The flag now breaks some OS X machines.
Remove it.
I have run the original program from issue 497 successfully
without the flag on both OS X and Linux machines.
Russ Cox [Mon, 28 Oct 2013 23:40:40 +0000 (19:40 -0400)]
runtime: relax preemption assertion during stack split
The case can happen when starttheworld is calling acquirep
to get things moving again and acquirep gets preempted.
The stack trace is in golang.org/issue/6644.
It is difficult to build a short test case for this, but
the person who reported issue 6644 confirms that this
solves the problem.
Fixes #6644.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/18740044
Brad Fitzpatrick [Thu, 24 Oct 2013 22:51:19 +0000 (15:51 -0700)]
strings: fix Replacer bug with prefix matches
singleStringReplacer had a bug where if a string was replaced
at the beginning and no output had yet been produced into the
temp buffer before matching ended, an invalid nil check (used
as a proxy for having matched anything) meant it always
returned its input.
Fixes #6659
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/16880043
Adam Langley [Mon, 21 Oct 2013 20:35:09 +0000 (16:35 -0400)]
crypto/tls: advertise support for RSA+SHA1 in TLS 1.2 handshake.
Despite SHA256 support being required for TLS 1.2 handshakes, some
servers are aborting handshakes that don't offer SHA1 support.
This change adds support for signing TLS 1.2 ServerKeyExchange messages
with SHA1. It does not add support for signing TLS 1.2 client
certificates with SHA1 as that would require the handshake to be
buffered.
Fixes #6618.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/15650043
Russ Cox [Fri, 18 Oct 2013 19:56:25 +0000 (15:56 -0400)]
cmd/cgo: stop using compiler error message text to analyze C names
The old approach to determining whether "name" was a type, constant,
or expression was to compile the C program
name;
and scan the errors and warnings generated by the compiler.
This requires looking for specific substrings in the errors and warnings,
which ties the implementation to specific compiler versions.
As compilers change their errors or drop warnings, cgo breaks.
This happens slowly but it does happen.
Clang in particular (now required on OS X) has a significant churn rate.
The new approach compiles a slightly more complex program
that is either valid C or not valid C depending on what kind of
thing "name" is. It uses only the presence or absence of an error
message on a particular line, not the error text itself. The program is:
// error if and only if name is undeclared
void f1(void) { typeof(name) *x; }
// error if and only if name is not a type
void f2(void) { name *x; }
// error if and only if name is not an integer constant
void f3(void) { enum { x = (name)*1 }; }
I had not been planning to do this until Go 1.3, because it is a
non-trivial change, but it fixes a real Xcode 5 problem in Go 1.2,
and the new code is easier to understand than the old code.
It should be significantly more robust.
Dmitriy Vyukov [Fri, 18 Oct 2013 06:45:19 +0000 (10:45 +0400)]
runtime: remove nomemprof
Nomemprof seems to be unneeded now, there is no recursion.
If the recursion will be re-introduced, it will break loudly by deadlocking.
Fixes #6566.
Alberto García Hierro [Thu, 17 Oct 2013 16:02:32 +0000 (09:02 -0700)]
database/sql: make tests repeatable with -cpu=n,n
New test added in CL 14611045 causes a deadlock when
running the tests with -cpu=n,n because the fakedb
driver always waits when opening a new connection after
running TestConnectionLeak. Reset its state after.
Robert Griesemer [Wed, 16 Oct 2013 23:16:54 +0000 (16:16 -0700)]
spec: clarify re-use of underlying arrays in slice operations
Please note the slight rewording for append: The spec now
requires that append reuses the underlying array if it is
sufficiently large. Per majority sentiment.
This is technically a language change but the current
implementation always worked this way.
Alberto García Hierro [Wed, 16 Oct 2013 16:22:57 +0000 (09:22 -0700)]
database/sql: Fix connection leak and potential deadlock
CL 10726044 introduced a race condition which causes connections
to be leaked under certain circumstances. If SetMaxOpenConns is
used, the application eventually deadlocks. Otherwise, the number
of open connections just keep growing indefinitely.
Russ Cox [Tue, 15 Oct 2013 19:00:48 +0000 (15:00 -0400)]
cmd/cgo: print the builtin prolog after the per-file preamble
The preamble may want to #define some special symbols
and then #include <sys/types.h> itself. The builtin prolog
also #includes <sys/types.h>, which would break such a
preamble (because the second #include will be a no-op).
The use of sys/types.h in the builtin prolog is new since Go 1.1,
so this should preserve the semantics of more existing cgo
code than we would otherwise.
It also fixes src/pkg/syscall/mkall.sh's use of go tool cgo -godefs
on some Linux systems.
undone because the change slows down profile collection
significantly and unpredictable at times (see comments
at https://golang.org/cl/14231047 for details)
««« original CL description
runtime: collect profiles even while on g0 stack
Rob Pike [Fri, 11 Oct 2013 00:26:03 +0000 (17:26 -0700)]
doc/effective_go.html: fix a couple of cosmetic issues
At the moment, godoc expands the example in the link, but in
the past it has not. Add a waffle word to allow either possibility.
Also change the order of cases in the switch in Compare to
be consistent with the other switch in the function.
Dominik Honnef [Thu, 10 Oct 2013 23:30:47 +0000 (16:30 -0700)]
codereview: fix hg sync closing of CLs for subrepositories
The regexp for closing CLs that were sent by you but committed by
someone else only matched messages for the main repository,
because of the added &repo=... for subrepositories.
R=golang-dev, r
CC=golang-dev
https://golang.org/cl/14512045
Instead of adding an -march=armv5t flag to the gcc command
line, the same effect is obtained with an ".arch armv5t"
pseudo op in the assembly file that uses armv5t instructions.
R=golang-dev, iant, dave
CC=golang-dev
https://golang.org/cl/14511044