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
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
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
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
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
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
CL 22730043 fixed a bug in these functions: they could
return 1.0 despite documentation saying otherwise.
But the fix changed the values returned in the non-buggy case too,
which might invalidate programs depending on a particular
stream when using rand.Seed(0) or when passing their own
Source to rand.New.
The example test says:
// These tests serve as an example but also make sure we don't change
// the output of the random number generator when given a fixed seed.
so I think there is some justification for thinking we have
promised not to change the values. In any case, there's no point in
changing the values gratuitously: we can easily fix this bug without
changing the values, and so we should.
That CL just changed the test values too, which defeats the
stated purpose, but it was just a comment.
Add an explicit regression test, which might be
a clearer signal next time that we don't want to change
the values.
Fixes#6721. (again)
Fixes#8013.
LGTM=r
R=iant, r
CC=golang-codereviews
https://golang.org/cl/95460049
Currently freeOSMemory makes only marking phase of GC, but not sweeping phase.
So recently memory is not released after freeOSMemory.
Do both marking and sweeping during freeOSMemory.
Fixes#8019.
LGTM=khr
R=golang-codereviews, khr
CC=golang-codereviews, rsc
https://golang.org/cl/97550043
Rename Seek to seek in asm file, was overlooked in CL 99320043.
LGTM=bradfitz, r
R=r, rsc, bradfitz
CC=golang-codereviews
https://golang.org/cl/99320044
These functions claimed to return error (an interface)
and be implemented entirely in assembly, but it's not
possible to create an interface from assembly
(at least not easily).
In reality the functions were written to return an errno uintptr
despite the Go prototype saying error.
When the errno was 0, they coincidentally filled out a nil error
by writing the 0 to the type word of the interface.
If the errno was ever non-zero, the functions would
create a non-nil error that would crash when trying to
call err.Error().
Luckily these functions (Seek, Time, Gettimeofday) pretty
much never fail, so it was all kind of working.
Found by go vet.
LGTM=bradfitz, r
R=golang-codereviews, bradfitz, r
CC=golang-codereviews
https://golang.org/cl/99320043
TestLargeDefs was issuing over one million small writes to
create a 7MB file (large.go). This is quite slow on Plan 9
since our disk file systems aren't very fast and they're
usually accessed over the network.
Buffering the writes makes the test about six times faster.
Even on Linux, it's about 1.5 times faster.
Here are the results on a slow Plan 9 machine:
Before:
% ./pack.test -test.v -test.run TestLargeDefs
=== RUN TestLargeDefs
--- PASS: TestLargeDefs (125.11 seconds)
PASS
After:
% ./pack.test -test.v -test.run TestLargeDefs
=== RUN TestLargeDefs
--- PASS: TestLargeDefs (20.835 seconds)
PASS
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/95040044
The introduction of temporaries in order.c was not
quite right for two corner cases:
1) The rewrite that pushed new variables on the lhs of
a receive into the body of the case was dropping the
declaration of the variables. If the variables escape,
the declaration is what allocates them.
Caught by escape analysis sanity check.
In fact the declarations should move into the body
always, so that we only allocate if the corresponding
case is selected. Do that. (This is an optimization that
was already present in Go 1.2. The new order code just
made it stop working.)
Fixes#7997.
2) The optimization to turn a single-recv select into
an ordinary receive assumed it could take the address
of the destination; not so if the destination is _.
Fixes#7998.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/100480043
Calling tar.Reader.Read() used to work fine, but without this patch it panics.
Simply return EOF to indicate the tar.Reader.Next() needs to be called.
LGTM=iant, bradfitz
R=golang-codereviews, bradfitz, iant, mikioh.mikioh, dominik.honnef
CC=golang-codereviews
https://golang.org/cl/94530043
This CL restores dropped constants not supported in OpenBSD 5.5
and tris to keep the promise of API compatibility.
Update #7049
LGTM=jsing, bradfitz, rsc
R=rsc, jsing, robert.hencke, minux.ma, bradfitz, iant
CC=golang-codereviews
https://golang.org/cl/96970043
- use Init to establish heap invariant on
a non-empty heap
- use Fix to update heap after an element's
properties have been changed
(The old code used Init where it wasn't needed,
and didn't use Fix because Fix was added after
the example was written.)
LGTM=bradfitz
R=adonovan, bradfitz
CC=golang-codereviews
https://golang.org/cl/94520043
for GOOS in darwin freebsd linux nacl netbsd openbsd plan9 solaris windows
do
for GOARCH in 386 amd64 amd64p32 arm
do
go vet
done
done
These are all real mistakes being corrected, but none
of them should be able to cause problems today
due to the NOSPLIT on the functions.
However, vet has also identified a few important problems.
I'm sending this CL to get rid of the trivial 'go vet' results
before attacking the real ones.
LGTM=r
R=golang-codereviews, r, bradfitz
CC=golang-codereviews
https://golang.org/cl/95460046
None of these are real bugs.
The variable name in the reference is not semantically meaningful,
except that 'go vet' will double check the offset against the name for you.
The stack sizes being corrected really are incorrect but they are also
in NOSPLIT functions so they typically don't matter.
Found by vet.
GOOS=linux GOARCH=amd64 go vet sync/atomic
GOOS=linux GOARCH=amd64p32 go vet sync/atomic
GOOS=linux GOARCH=386 go vet sync/atomic
GOOS=linux GOARCH=arm go vet sync/atomic
GOOS=freebsd GOARCH=arm go vet sync/atomic
GOOS=netbsd GOARCH=arm go vet sync/atomic
LGTM=r
R=r, bradfitz
CC=golang-codereviews
https://golang.org/cl/100500043
The GC program describing a data structure sometimes trusts the
pointer base type and other times does not (if not, the garbage collector
must fall back on per-allocation type information stored in the heap).
Make the scanning of a pointer in an interface do the same.
This fixes a crash in a particular use of reflect.SliceHeader.
Fixes#8004.
LGTM=khr
R=golang-codereviews, khr
CC=0xe2.0x9a.0x9b, golang-codereviews, iant, r
https://golang.org/cl/100470045
Globals, function arguments, and results are special cases in
registerization.
Globals must be flushed aggressively, because nearly any
operation can cause a panic, and the recovery code must see
the latest values. Globals also must be loaded aggressively,
because nearly any store through a pointer might be updating a
global: the compiler cannot see all the "address of"
operations on globals, especially exported globals. To
accomplish this, mark all globals as having their address
taken, which effectively disables registerization.
If a function contains a defer statement, the function results
must be flushed aggressively, because nearly any operation can
cause a panic, and the deferred code may call recover, causing
the original function to return the current values of its
function results. To accomplish this, mark all function
results as having their address taken if the function contains
any defer statements. This causes not just aggressive flushing
but also aggressive loading. The aggressive loading is
overkill but the best we can do in the current code.
Function arguments must be considered live at all safe points
in a function, because garbage collection always preserves
them: they must be up-to-date in order to be preserved
correctly. Accomplish this by marking them live at all call
sites. An earlier attempt at this marked function arguments as
having their address taken, which disabled registerization
completely, making programs slower. This CL's solution allows
registerization while preserving safety. The benchmark speedup
is caused by being able to registerize again (the earlier CL
lost the same amount).
benchmark old ns/op new ns/op delta
BenchmarkEqualPort32 61.4 56.0 -8.79%
benchmark old MB/s new MB/s speedup
BenchmarkEqualPort32 521.56 570.97 1.09x
Fixes#1304. (again)
Fixes#7944. (again)
Fixes#7984.
Fixes#7995.
LGTM=khr
R=golang-codereviews, khr
CC=golang-codereviews, iant, r
https://golang.org/cl/97500044
The function takes 32 bytes of arguments: 8 for the *block
and then 3*8 for the slice.
The 24 is not causing a bug (today at least) because the
final word is the cap of the slice, which the assembly
does not use.
Identified by 'go vet std'.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/96360043
Turns out elf.File.Sections is indexed by the actual
section number, not the number minus one.
I don't know why I thought the -1 was necessary.
Fixes objdump test (and therefore build) on ELF systems.
While we're here, fix bounds on gnuDump so that we
don't crash when asked to disassemble outside
the text segment. May fix Windows build or at least
make the failure more interesting.
TBR=iant
CC=golang-codereviews
https://golang.org/cl/92390043
There is some duplication here with cmd/nm.
There is a TODO to address that after 1.3 is out.
Update #7452
x86 disassembly works and is tested.
The arm disassembler does not exist yet
and is therefore not yet hooked up.
LGTM=crawshaw, iant
R=crawshaw, iant
CC=golang-codereviews
https://golang.org/cl/91360046
Do not use ustar format if we need the GNU one.
Change \000 to \x00 for consistency
Check for "ustar\x00" instead of "ustar\x00\x00" for conistency with tar
and compatiblity with archive generated with older code (which was ustar\x00\x20\x00)
Add test for long name + big file.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/99050043
AddressSanitizer says:
AddressSanitizer: heap-buffer-overflow on address 0x60200001b6f3
READ of size 6 at 0x60200001b6f3 thread T0
#0 0x46741b in __interceptor_memcmp asan_interceptors.cc:337
#1 0x4b5794 in compile src/cmd/6g/../gc/pgen.c:177
#2 0x509b81 in funccompile src/cmd/gc/dcl.c:1457
#3 0x520fe2 in p9main src/cmd/gc/lex.c:489
#4 0x5e2e01 in main src/lib9/main.c:57
#5 0x7fab81f7976c in __libc_start_main /build/buildd/eglibc-2.15/csu/libc-start.c:226
#6 0x4b16dc in _start (pkg/tool/linux_amd64/6g+0x4b16dc)
0x60200001b6f3 is located 0 bytes to the right of 3-byte region [0x60200001b6f0,0x60200001b6f3)
allocated by thread T0 here:
#0 0x493ec8 in __interceptor_malloc asan_malloc_linux.cc:75
#1 0x54d64e in mal src/cmd/gc/subr.c:459
#2 0x5260d5 in yylex src/cmd/gc/lex.c:1605
#3 0x52078f in p9main src/cmd/gc/lex.c:402
#4 0x5e2e01 in main src/lib9/main.c:57
If the memory block happens to be at the end of hunk and page bounadry,
this out-of-bounds can lead to a crash.
LGTM=dave, iant
R=golang-codereviews, dave, iant
CC=golang-codereviews
https://golang.org/cl/93370043
The code recurs very deeply in cases like (?:x{1,1000}){1,1000}
Since if much time is spent checking whether one pass is possible, it's not
worth doing at all, a simple fix is proposed: Stop if the check takes too long.
To do this, we simply avoid machines with >1000 instructions.
Benchmarks show a percent or less change either way, effectively zero.
Fixes#7608.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/92290043
If a map variable is created with reflect.New it has incorrect type (map[unsafe.Pointer]unsafe.Pointer).
If GC follows such pointer, it scans Hmap and buckets with incorrect type.
This can lead to overscan of up to 120 bytes for map[int8]struct{}.
Which in turn can lead to crash if the memory after a bucket object is unaddressable
or false retention (buckets are scanned as arrays of unsafe.Pointer).
I don't see how it can lead to heap corruptions, though.
LGTM=khr
R=rsc, khr
CC=golang-codereviews
https://golang.org/cl/96270044
mstats.last_gc is unix time now, it is compared with abstract monotonic time.
On my machine GC is forced every 5 mins regardless of last_gc.
LGTM=rsc
R=golang-codereviews
CC=golang-codereviews, iant, rsc
https://golang.org/cl/91350045
I have no test case for this at tip.
The original report included a program crashing at revision 88ac7297d2fa.
I tested this code at that revision and it does fix the crash.
However, at tip the reported code no longer crashes, presumably
because some allocation patterns have changed. I believe the
bug is still present at tip and that this code still fixes it.
Fixes#7143.
LGTM=alex.brainman
R=golang-codereviews, alex.brainman
CC=dvyukov, golang-codereviews
https://golang.org/cl/96300046
Originally it was an error, which made perfect sense, but in issue 2540
I got talked out of this sensible behavior. I'm not thrilled with the "new"
behavior but it's been there since Go 1.1 so we're stuck with it now.
Fixes#6724.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/100430043
This changes allows the first token encoded to be a xml declaration. A ProcInst with target of xml. Any other ProcInst after that with a target of xml will fail
Fixes#7380.
LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://golang.org/cl/72410043
The inputs to a function are marked live at all times in the
liveness bitmaps, so that the garbage collector will not free
the things they point at and reuse the pointers, so that the
pointers shown in stack traces are guaranteed not to have
been recycled.
Unfortunately, no one told the register optimizer that the
inputs need to be preserved at all call sites. If a function
is done with a particular input value, the optimizer will stop
preserving it across calls. For single-word values this just
means that the value recorded might be stale. For multi-word
values like slices, the value recorded could be only partially stale:
it can happen that, say, the cap was updated but not the len,
or that the len was updated but not the base pointer.
Either of these possibilities (and others) would make the
garbage collector misinterpret memory, leading to memory
corruption.
This came up in a real program, in which the garbage collector's
'slice len ≤ slice cap' check caught the inconsistency.
Fixes#7944.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews, khr
https://golang.org/cl/100370045
This is joint work with Daniel Morsing.
In order for the register allocator to alias two variables, they must have the same width, stack offset, and etype. Code generation was altering a variable's etype in a few places. This prevented the variable from being moved to a register, which in turn prevented peephole optimization. This failure to alias was very common, with almost 23,000 instances just running make.bash.
This phenomenon was not visible in the register allocation debug output because the variables that failed to alias had the same name. The debugging-only change to bits.c fixes this by printing the variable number with its name.
This CL fixes the source of all etype mismatches for 6g, all but one case for 8g, and depressingly few cases for 5g. (I believe that extending CL 6819083 to 5g is a prerequisite.) Fixing the remaining cases in 8g and 5g is work for the future.
The etype mismatch fixes are:
* [gc] Slicing changed the type of the base pointer into a uintptr in order to perform arithmetic on it. Instead, support addition directly on pointers.
* [*g] OSPTR was giving type uintptr to slice base pointers; undo that. This arose, for example, while compiling copy(dst, src).
* [8g] 64 bit float conversion was assigning int64 type during codegen, overwriting the existing uint64 type.
Note that some etype mismatches are appropriate, such as a struct with a single field or an array with a single element.
With these fixes, the number of registerizations that occur while running make.bash for 6g increases ~10%. Hello world binary size shrinks ~1.5%. Running all benchmarks in the standard library show performance improvements ranging from nominal to substantive (>10%); a full comparison using 6g on my laptop is available at https://gist.github.com/josharian/8f9b5beb46667c272064. The microbenchmarks must be taken with a grain of salt; see issue 7920. The few benchmarks that show real regressions are likely due to issue 7920. I manually examined the generated code for the top few regressions and none had any assembly output changes. The few benchmarks that show extraordinary improvements are likely also due to issue 7920.
Performance results from 8g appear similar to 6g.
5g shows no performance improvements. This is not surprising, given the discussion above.
Update #7316
LGTM=rsc
R=rsc, daniel.morsing, bradfitz
CC=dave, golang-codereviews
https://golang.org/cl/91850043
The runtime was detecting the cycle already,
but we can give a better error without even
building the binary.
Fixes#7789.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/96290043
This change requires using SWIG version 3.0 or later. Earlier
versions of SWIG do not generate the pragmas required to use
the external linker.
Fixes#7155.
Fixes#7156.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/97120046
Before we used line 1 of the first source file.
This should be clearer.
Fixes#4388.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/92250044
<enter reason for undo>
««« original CL description
net: make use of SO_LINGER_SEC on darwin
Fixes#7971.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/92210044
»»»
TBR=iant
R=golang-codereviews
CC=golang-codereviews
https://golang.org/cl/96220049
If it's not used (such as on other systems or if softfloat
is disabled) the linker will discard it.
The alternative is to teach cmd/go that every binary
depends on math implicitly on arm. I started down that
path but it's too scary. If we're going to get dependencies
right we should get dependencies right.
Fixes#6994.
LGTM=bradfitz, dave
R=golang-codereviews, bradfitz, dave
CC=golang-codereviews
https://golang.org/cl/95290043
This is a trivial change to make use of an existing `nl` byte slice
containing a single '\n' character. It's already declared and
used in another place in this file, so it might as well be used
in the other location instead of
a new slice literal. There should be no change in behavior,
aside from potentially less allocations.
This is my first CL, so I wanted to use a simple, hopefully non-controversial,
minor improvement to get more comfortable with golang contribution process.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/97280043
<enter reason for undo>
««« original CL description
runtime/race: fix the link for the race detector.
LGTM=bradfitz
R=golang-dev, bradfitz
CC=golang-codereviews
https://golang.org/cl/100330043
»»»
TBR=minux
R=minux.ma
CC=golang-codereviews
https://golang.org/cl/96200044
list has been adding them one at a time haphazardly
(race and tags were there and documented; compiler
was there and undocumented).
clean -i needs -compiler in order to clean the
installed targets for alternate compilers.
Fixes#7302.
While we're here, tweak the language in the 'go get' docs
about build flags.
Fixes#7807.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/99130043
If you write:
var x = 3
then the compiler arranges for x to be initialized in the linker
with an actual 3 from the data segment, rather than putting
x in the bss and emitting init-time "x = 3" assignment code.
If you write:
var y = x
var x = 3
then the compiler is clever and treats this the same as if
the code said 'y = 3': they both end up in the data segment
with no init-time assignments.
If you write
var y = x
var x int
then the compiler was treating this the same as if the
code said 'x = 0', making both x and y zero and avoiding
any init-time assignment.
This copying optimization to avoid init-time assignment of y
is incorrect if 'var x int' doesn't mean 'x = 0' but instead means
'x is initialized in C or assembly code'. The program ends up
with 'y = 0' instead of 'y = the value specified for x in that other code'.
Disable the propagation if there is no initializer for x.
This comes up in some uses of cgo, because cgo generates
Go globals that are initialized in accompanying C files.
Fixes#7665.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/93200044
If the ... element type contained no pointers,
then the escape analysis did not track the ... itself.
This manifested in an escaping ...byte being treated
as non-escaping.
Fixes#7934.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/100310043
The register allocator decides which variables should be placed into registers by charging for each load/store and crediting for each use, and then selecting an allocation with minimal cost. NOPs will be eliminated, however, so using a variable in a NOP should not generate credit.
Issue 7867 arises from attempted registerization of multi-word variables because they are used in NOPs. By not crediting for that use, they will no longer be considered for registerization.
This fix could theoretically lead to better register allocation, but NOPs are rare relative to other instructions.
Fixes#7867.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/94810044
TestDialFailPDLeak was created for testing runtime-integrated netwrok
poller stuff and used during Go 1.2 development cycle. Unfortunately
it's still flakey because it depends on MemStats of runtime, not
pollcache directly, and MemStats accounts and revises its own stats
occasionally.
For now the codepaths related to runtime-intergrated network poller
are pretty stable, so removing this test case never suffers us.
Fixes#6553.
LGTM=josharian, iant
R=iant, josharian
CC=golang-codereviews
https://golang.org/cl/98080043
There was confusion in the behavior of json.Indent; This change
attempts to clarify the behavior by providing a bit more verbiage
to the documentation as well as provide an example function.
Fixes#7821.
LGTM=robert.hencke, adg
R=golang-codereviews, minux.ma, bradfitz, aram, robert.hencke, r, adg
CC=golang-codereviews
https://golang.org/cl/97840044
Existing test TestMaxOpenConns was failing occasionally, especially
with higher values of GOMAXPROCS.
Fixes#7532
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/95130043
