The old limit of 5 was chosen because we didn't actually know how
many bytes of arguments there were; 5 was a halfway point between
printing some useful information and looking ridiculous.
Now we know how many bytes of arguments there are, and we stop
the printing when we reach that point, so the "looking ridiculous" case
doesn't happen anymore: we only print actual argument words.
The cutoff now serves only to truncate very long (but real) argument lists.
In multiple debugging sessions recently (completely unrelated bugs)
I have been frustrated by not seeing more of the long argument lists:
5 words is only 2.5 interface values or strings, and not even 2 slices.
Double the max amount we'll show.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews, iant, r
https://golang.org/cl/83850043
The data field is the generic array that acts as a standin
for the keys and values arrays for the generic runtime code.
We want to substitute the keys and values arrays for the data
array, not just add keys and values in addition to it.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/81160044
Darwin 10.6 (gcc 4.2) and some older versions of gcc default to C90 mode, not C99 mode. Silence the warning.
LGTM=aram, iant
R=golang-codereviews, aram, iant
CC=golang-codereviews
https://golang.org/cl/83090050
There is no way to call them from outside the net package.
They are used to implement UCPConn.ReadMsgUDP and similar.
LGTM=mikioh.mikioh
R=golang-codereviews, mikioh.mikioh
CC=golang-codereviews
https://golang.org/cl/83730044
Reduce footprint of liveness bitmaps by about 5x.
1. Mark all liveness bitmap symbols as 4-byte aligned
(they were aligned to a larger size by default).
2. The bitmap data is a bitmap count n followed by n bitmaps.
Each bitmap begins with its own count m giving the number
of bits. All the m's are the same for the n bitmaps.
Emit this bitmap length once instead of n times.
3. Many bitmaps within a function have the same bit values,
but each call site was given a distinct bitmap. Merge duplicate
bitmaps so that no bitmap is written more than once.
4. Many functions end up with the same aggregate bitmap data.
We used to name the bitmap data funcname.gcargs and funcname.gclocals.
Instead, name it gclocals.<md5 of data> and mark it dupok so
that the linker coalesces duplicate sets. This cut the bitmap
data remaining after step 3 by 40%; I was not expecting it to
be quite so dramatic.
Applied to "go build -ldflags -w code.google.com/p/go.tools/cmd/godoc":
bitmaps pclntab binary on disk
before this CL 1326600 1985854 12738268
4-byte align 1154288 (0.87x) 1985854 (1.00x) 12566236 (0.99x)
one bitmap len 782528 (0.54x) 1985854 (1.00x) 12193500 (0.96x)
dedup bitmap 414748 (0.31x) 1948478 (0.98x) 11787996 (0.93x)
dedup bitmap set 245580 (0.19x) 1948478 (0.98x) 11620060 (0.91x)
While here, remove various dead blocks of code from plive.c.
Fixes#6929.
Fixes#7568.
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/83630044
warning: src/cmd/8g/ggen.c:35 non-interruptable temporary
warning: src/cmd/gc/walk.c:656 set and not used: l
warning: src/cmd/gc/walk.c:658 set and not used: l
LGTM=minux.ma
R=golang-codereviews, minux.ma
CC=golang-codereviews
https://golang.org/cl/83660043
1. Use n->alloc, not n->left, to hold the allocated temp being
passed from orderstmt/orderexpr to walk.
2. Treat method values the same as closures.
3. Use killed temporary for composite literal passed to
non-escaping function argument.
4. Clean temporaries promptly in if and for statements.
5. Clean temporaries promptly in select statements.
As part of this, move all the temporary-generating logic
out of select.c into order.c, so that the temporaries can
be reclaimed.
With the new temporaries, can re-enable the 1-entry
select optimization. Fixes issue 7672.
While we're here, fix a 1-line bug in select processing
turned up by the new liveness test (but unrelated; select.c:72).
Fixes#7686.
6. Clean temporaries (but not particularly promptly) in switch
and range statements.
7. Clean temporary used during convT2E/convT2I.
8. Clean temporaries promptly during && and || expressions.
---
CL 81940043 reduced the number of ambiguously live temps
in the godoc binary from 860 to 711.
CL 83090046 reduced the number from 711 to 121.
This CL reduces the number from 121 to 23.
15 the 23 that remain are in fact ambiguously live.
The final 8 could be fixed but are not trivial and
not common enough to warrant work at this point
in the release cycle.
These numbers only count ambiguously live temps,
not ambiguously live user-declared variables.
There are 18 such variables in the godoc binary after this CL,
so a total of 41 ambiguously live temps or user-declared
variables.
The net effect is that zeroing anything on entry to a function
should now be a rare event, whereas earlier it was the
common case.
This is good enough for Go 1.3, and probably good
enough for future releases too.
Fixes#7345.
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/83000048
DragonFlyBSD, FreeBSD 9 and beyond, NetBSD 6 and beyond, and
Solaris (illumos) support AF_UNIX+SOCK_SEQPACKET socket.
LGTM=dave
R=golang-codereviews, dave
CC=golang-codereviews
https://golang.org/cl/83390043
This CL tries to fill the gap between Linux and other Unix-like systems
in the same way UDPConn already did.
Fixes#7677.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/83330045
1. In functions with heap-allocated result variables or with
defer statements, the return sequence requires more than
just a single RET instruction. There is an optimization that
arranges for all returns to jump to a single copy of the return
epilogue in this case. Unfortunately, that optimization is
fundamentally incompatible with PC-based liveness information:
it takes PCs at many different points in the function and makes
them all land at one PC, making the combined liveness information
at that target PC a mess. Disable this optimization, so that each
return site gets its own copy of the 'call deferreturn' and the
copying of result variables back from the heap.
This removes quite a few spurious 'ambiguously live' variables.
2. Let orderexpr allocate temporaries that are passed by address
to a function call and then die on return, so that we can arrange
an appropriate VARKILL.
2a. Do this for ... slices.
2b. Do this for closure structs.
2c. Do this for runtime.concatstring, which is the implementation
of large string additions. Change representation of OADDSTR to
an explicit list in typecheck to avoid reconstructing list in both
walk and order.
3. Let orderexpr allocate the temporary variable copies used for
range loops, so that they can be killed when the loop is over.
Similarly, let it allocate the temporary holding the map iterator.
CL 81940043 reduced the number of ambiguously live temps
in the godoc binary from 860 to 711.
This CL reduces the number to 121. Still more to do, but another
good checkpoint.
Update #7345
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/83090046
There's enough jitter in the scheduler on overloaded machines
that 25ms is not enough.
LGTM=dave
R=golang-codereviews, gobot, rsc, dave
CC=golang-codereviews
https://golang.org/cl/83300044
REP MOVSQ and REP STOSQ have a really high startup overhead.
Use a Duff's device to do the repetition instead.
benchmark old ns/op new ns/op delta
BenchmarkClearFat32 7.20 1.60 -77.78%
BenchmarkCopyFat32 6.88 2.38 -65.41%
BenchmarkClearFat64 7.15 3.20 -55.24%
BenchmarkCopyFat64 6.88 3.44 -50.00%
BenchmarkClearFat128 9.53 5.34 -43.97%
BenchmarkCopyFat128 9.27 5.56 -40.02%
BenchmarkClearFat256 13.8 9.53 -30.94%
BenchmarkCopyFat256 13.5 10.3 -23.70%
BenchmarkClearFat512 22.3 18.0 -19.28%
BenchmarkCopyFat512 22.0 19.7 -10.45%
BenchmarkCopyFat1024 36.5 38.4 +5.21%
BenchmarkClearFat1024 35.1 35.0 -0.28%
TODO: use for stack frame zeroing
TODO: REP prefixes are still used for "reverse" copying when src/dst
regions overlap. Might be worth fixing.
LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews, r
https://golang.org/cl/81370046
The old code was using the PC of the instruction after the CALL.
Variables live during the call but not live when it returns would
not be seen as live during the stack copy, which might lead to
corruption. The correct PC to use is the one just before the
return address. After this CL the lookup matches what mgc0.c does.
The only time this matters is if you have back to back CALL instructions:
CALL f1 // x live here
CALL f2 // x no longer live
If a stack copy occurs during the execution of f1, the old code will
use the liveness bitmap intended for the execution of f2 and will not
treat x as live.
The only way this situation can arise and cause a problem in a stack copy
is if x lives on the stack has had its address taken but the compiler knows
enough about the context to know that x is no longer needed once f1
returns. The compiler has never known that much, so using the f2 context
cannot currently cause incorrect execution. For the same reason, it is not
possible to write a test for this today.
CL 83090046 will make the compiler precise enough in some cases
that this distinction will start mattering. The existing stack growth tests
in package runtime will fail if that CL is submitted without this one.
While we're here, print the frame PC in debug mode and update the
bitmap interpretation strings.
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/83250043
The new channel and map runtime routines take pointers
to values, typically temporaries. Without help, the compiler
cannot tell when those temporaries stop being needed,
because it isn't sure what happened to the pointer.
Arrange to insert explicit VARKILL instructions for these
temporaries so that the liveness analysis can avoid seeing
them as "ambiguously live".
The change is made in order.c, which was already in charge of
introducing temporaries to preserve the order-of-evaluation
guarantees. Now its job has expanded to include introducing
temporaries as needed by runtime routines, and then also
inserting the VARKILL annotations for all these temporaries,
so that their lifetimes can be shortened.
In order to do its job for the map runtime routines, order.c arranges
that all map lookups or map assignments have the form:
x = m[k]
x, y = m[k]
m[k] = x
where x, y, and k are simple variables (often temporaries).
Likewise, receiving from a channel is now always:
x = <-c
In order to provide the map guarantee, order.c is responsible for
rewriting x op= y into x = x op y, so that m[k] += z becomes
t = m[k]
t2 = t + z
m[k] = t2
While here, fix a few bugs in order.c's traversal: it was failing to
walk into select and switch case bodies, so order of evaluation
guarantees were not preserved in those situations.
Added tests to test/reorder2.go.
Fixes#7671.
In gc/popt's temporary-merging optimization, allow merging
of temporaries with their address taken as long as the liveness
ranges do not intersect. (There is a good chance of that now
that we have VARKILL annotations to limit the liveness range.)
Explicitly killing temporaries cuts the number of ambiguously
live temporaries that must be zeroed in the godoc binary from
860 to 711, or -17%. There is more work to be done, but this
is a good checkpoint.
Update #7345
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/81940043
GODEBUG=allocfreetrace=1:
The allocfreetrace=1 mode prints a stack trace for each block
allocated and freed, and also a stack trace for each garbage collection.
It was implemented by reusing the heap profiling support: if allocfreetrace=1
then the heap profile was effectively running at 1 sample per 1 byte allocated
(always sample). The stack being shown at allocation was the stack gathered
for profiling, meaning it was derived only from the program counters and
did not include information about function arguments or frame pointers.
The stack being shown at free was the allocation stack, not the free stack.
If you are generating this log, you can find the allocation stack yourself, but
it can be useful to see exactly the sequence that led to freeing the block:
was it the garbage collector or an explicit free? Now that the garbage collector
runs on an m0 stack, the stack trace for the garbage collector was never interesting.
Fix all these problems:
1. Decouple allocfreetrace=1 from heap profiling.
2. Print the standard goroutine stack traces instead of a custom format.
3. Print the stack trace at time of allocation for an allocation,
and print the stack trace at time of free (not the allocation trace again)
for a free.
4. Print all goroutine stacks at garbage collection. Having all the stacks
means that you can see the exact point at which each goroutine was
preempted, which is often useful for identifying liveness-related errors.
GODEBUG=gcdead=1:
This mode overwrites dead pointers with a poison value.
Detect the poison value as an invalid pointer during collection,
the same way that small integers are invalid pointers.
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/81670043
e.g., don't delete /dev/null. this fix inspired by gnu libiberty,
unlink-if-ordinary.c.
Fixes#7563
LGTM=iant
R=golang-codereviews, iant, 0intro
CC=golang-codereviews, r
https://golang.org/cl/76810045
On DragonFly BSD, we adjust the ephemeral port range because
unlike other BSD systems its default ephemeral port range
doesn't conform to IANA recommendation as described in RFC 6355
and is pretty narrow.
On DragonFly BSD 3.6: default range [1024, 5000], high range [49152, 65535]
On FreeBSD 10: default range [10000, 65535], high range [49152, 65535]
On Linux 3.11: default range [32768, 61000]
Fixes#7541.
LGTM=iant
R=jsing, gobot, iant
CC=golang-codereviews
https://golang.org/cl/80610044
SendmsgN is an alternate version Sendmsg that also returns
the number of bytes transferred, instead of just the error.
Update #7645
LGTM=aram, iant
R=iant, aram, bradfitz
CC=golang-codereviews
https://golang.org/cl/81210043
chanrecv now expects a pointer to the data to be filled in.
mapiterinit expects a pointer to the hash iterator to be filled in.
In both cases, the temporary being pointed at changes from
dead to alive during the call. In order to make sure it is
preserved if a garbage collection happens after that transition
but before the call returns, the temp must be marked as live
during the entire call.
But if it is live during the entire call, it needs to be safe for
the garbage collector to scan at the beginning of the call,
before the new data has been filled in. Therefore, it must be
zeroed by the caller, before the call. Do that.
My previous attempt waited to mark it live until after the
call returned, but that's unsafe (see first paragraph);
undo that change in plive.c.
This makes powser2 pass again reliably.
I looked at every call to temp in the compiler.
The vast majority are followed immediately by an
initialization of temp, so those are fine.
The only ones that needed changing were the ones
where the next operation is to pass the address of
the temp to a function call, and there aren't too many.
Maps are exempted from this because mapaccess
returns a pointer to the data and lets the caller make
the copy.
Fixes many builds.
TBR=khr
CC=golang-codereviews
https://golang.org/cl/80700046
This change sets systemSkip on a test where Go and CAPI have different
chain building behaviour. CAPI is correct, but aligning the Go code is
probably too large a change prior to 1.3.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/81620043
For now we strictly use IPV6_V6ONLY=1 for IPv6-only communications
and IPV6_V6ONLY=0 for both IPv4 and IPv6 communications. So let the
capability test do the same.
LGTM=iant
R=golang-codereviews, gobot, iant
CC=golang-codereviews
https://golang.org/cl/80140044
The root update on 3/11/2014 removed the Verisign root cert that the Go
tests use. This only affects the 'TestSystemVerify' test in
crypto/x509.
Fixes#7523.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/80000044
cgo represents all 0-sized and unsized types internally as [0]byte. This means that pointers to incomplete types would be interchangable, even if given a name by typedef.
Fixes#7409.
LGTM=iant
R=golang-codereviews, bradfitz, iant
CC=golang-codereviews
https://golang.org/cl/76450043
This is the same check we use during stack copying.
The check cannot be applied to C stack frames, even
though we do emit pointer bitmaps for the arguments,
because (1) the pointer bitmaps assume all arguments
are always live, not true of outputs during the prologue,
and (2) the pointer bitmaps encode interface values as
pointer pairs, not true of interfaces holding integers.
For the rest of the frames, however, we should hold ourselves
to the rule that a pointer marked live really is initialized.
The interface scanning already implicitly checks this
because it interprets the type word as a valid type pointer.
This may slow things down a little because of the extra loads.
Or it may speed things up because we don't bother enqueuing
nil pointers anymore. Enough of the rest of the system is slow
right now that we can't measure it meaningfully.
Enable for now, even if it is slow, to shake out bugs in the
liveness bitmaps, and then decide whether to turn it off
for the Go 1.3 release (issue 7650 reminds us to do this).
The new m->traceback field lets us force printing of fp=
values on all goroutine stack traces when we detect a
bad pointer. This makes it easier to understand exactly
where in the frame the bad pointer is, so that we can trace
it back to a specific variable and determine what is wrong.
Update #7650
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/80860044
1. On entry to a function, only zero the ambiguously live stack variables.
Before, we were zeroing all stack variables containing pointers.
The zeroing is pretty inefficient right now (issue 7624), but there are also
too many stack variables detected as ambiguously live (issue 7345),
and that must be addressed before deciding how to improve the zeroing code.
(Changes in 5g/ggen.c, 6g/ggen.c, 8g/ggen.c, gc/pgen.c)
Fixes#7647.
2. Make the regopt word-based liveness analysis preserve the
whole-variable liveness property expected by the garbage collection
bitmap liveness analysis. That is, if the regopt liveness decides that
one word in a struct needs to be preserved, make sure it preserves
the entire struct. This is particularly important for multiword values
such as strings, slices, and interfaces, in which all the words need
to be present in order to understand the meaning.
(Changes in 5g/reg.c, 6g/reg.c, 8g/reg.c.)
Fixes#7591.
3. Make the regopt word-based liveness analysis treat a variable
as having its address taken - which makes it preserved across
all future calls - whenever n->addrtaken is set, for consistency
with the gc bitmap liveness analysis, even if there is no machine
instruction actually taking the address. In this case n->addrtaken
is incorrect (a nicer way to put it is overconservative), and ideally
there would be no such cases, but they can happen and the two
analyses need to agree.
(Changes in 5g/reg.c, 6g/reg.c, 8g/reg.c; test in bug484.go.)
Fixes crashes found by turning off "zero everything" in step 1.
4. Remove spurious VARDEF annotations. As the comment in
gc/pgen.c explains, the VARDEF must immediately precede
the initialization. It cannot be too early, and it cannot be too late.
In particular, if a function call sits between the VARDEF and the
actual machine instructions doing the initialization, the variable
will be treated as live during that function call even though it is
uninitialized, leading to problems.
(Changes in gc/gen.c; test in live.go.)
Fixes crashes found by turning off "zero everything" in step 1.
5. Do not treat loading the address of a wide value as a signal
that the value must be initialized. Instead depend on the existence
of a VARDEF or the first actual read/write of a word in the value.
If the load is in order to pass the address to a function that does
the actual initialization, treating the load as an implicit VARDEF
causes the same problems as described in step 4.
The alternative is to arrange to zero every such value before
passing it to the real initialization function, but this is a much
easier and more efficient change.
(Changes in gc/plive.c.)
Fixes crashes found by turning off "zero everything" in step 1.
6. Treat wide input parameters with their address taken as
initialized on entry to the function. Otherwise they look
"ambiguously live" and we will try to emit code to zero them.
(Changes in gc/plive.c.)
Fixes crashes found by turning off "zero everything" in step 1.
7. An array of length 0 has no pointers, even if the element type does.
Without this change, the zeroing code complains when asked to
clear a 0-length array.
(Changes in gc/reflect.c.)
LGTM=khr
R=khr
CC=golang-codereviews
https://golang.org/cl/80160044
Zeroing the outputs makes sure that during function calls
in those functions we do not let the garbage collector
treat uninitialized values as pointers.
The garbage collector may still see uninitialized values
if a preemption occurs during the function prologue,
before the zeroing has had a chance to run.
This reduces the number of 'bad pointer' messages when
that runtime check is enabled, but it doesn't fix all of them,
so the check is still disabled.
It will also avoid leaks, although I doubt any of these were
particularly serious.
LGTM=iant, khr
R=iant, khr
CC=golang-codereviews
https://golang.org/cl/80850044
This was added by the one-pass CL (post Go 1.2)
so it can still be removed.
Removing because surely there will be new operations
added later, and we can't change the constant value
once we define it, so "last" is a bad concept to expose.
Nothing uses it.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/81160043
The garbage collector will scan these pointers,
so make sure they are initialized.
LGTM=bradfitz, khr
R=khr, bradfitz
CC=golang-codereviews
https://golang.org/cl/80960047
If you compile a program that has cgo LDFLAGS directives, those are exported to an environment variable to be used by subsequent compiler tool invocations. The linking phase when using the gccgo toolchain did not consider the envvar CGO_LDFLAGS's linking directives resulting in undefined references when using cgo+gccgo.
Fixes#7573
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/80780043
GCC on OS X 10.6 doesn't support -Wuninitialized without -O.
Fixes#7492.
LGTM=iant
R=golang-codereviews, dave, iant
CC=golang-codereviews
https://golang.org/cl/72360045
m->moreargp/morebuf were not cleared in case of preemption and stack growing,
it can lead to persistent leaks of large memory blocks.
It seems to fix the sync.Pool finalizer failures. I've run the test 500'000 times
w/o a single failure; previously it would fail dozens of times.
Fixes#7633.
Fixes#7533.
LGTM=rsc
R=golang-codereviews
CC=golang-codereviews, khr, rsc
https://golang.org/cl/80480044
Update channel race annotations to support change in
cl/75130045: doc: allow buffered channel as semaphore without initialization
The new annotations are added only for channels with capacity 1.
Strictly saying it's possible to construct a counter-example that
will produce a false positive with capacity > 1. But it's hardly can
lead to false positives in real programs, at least I would like to see such programs first.
Any additional annotations also increase probability of false negatives,
so I would prefer to add them lazily.
LGTM=rsc
R=golang-codereviews
CC=golang-codereviews, iant, khr, rsc
https://golang.org/cl/76970043
Currently it's possible that bgsweep finishes before all spans
have been swept (we only know that sweeping of all spans has *started*).
In such case bgsweep may fail wake up runfinq goroutine when it needs to.
finq may still be nil at this point, but some finalizers may be queued later.
Make bgsweep to wait for sweeping to *complete*, then it can decide
whether it needs to wake up runfinq for sure.
Update #7533
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/75960043
If we set obj, then it will be enqueued for marking at the end of the scanning loop.
This is not necessary, since we've already marked it.
This can wait for 1.4 if you wish.
LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/80030043
Fixes#7627.
CL 61970044 changed the order in which .a files are passed to gccgo's link phase. However by reversing the order it caused gccgo to complain if both internal (liba.a) and external (liba_test.a) versions of a package were presented as the former would not contain all the necessary symbols, and the latter would duplicate symbols already defined.
This change ensures that all 'fake' targets remain at the top of the final link order which should be fine as a package compiled as an external test is a superset of its internal sibling.
Looking at how gcToolchain links tests I think this change now accurately mirrors those actions which present $WORK/_test before $WORK in the link order.
LGTM=iant
R=rsc, iant
CC=golang-codereviews, michael.hudson
https://golang.org/cl/80300043
Some platform that implements inp_localgroup-like shared internet
protocol control block group looks a bit sensitive about transport
layer protocol's address:port reuse. Sometimes it rejects a TCP SYN
packet using TCP RST, and sometimes silence.
For now, until test case refactoring, we admit few Dial failures on
TestTCPConcurrentAccept as a workaround.
Update #7400
Update #7541
LGTM=jsing
R=jsing
CC=golang-codereviews
https://golang.org/cl/75920043
The previous fix CL 69340044 still leaves a possibility of it.
This CL prevents the kernel, especially DragonFly BSD, from
performing unpredictable asynchronous connection establishment
on stream-based transport layer protocol sockets.
Update #7541
Update #7474
LGTM=jsing
R=jsing
CC=golang-codereviews
https://golang.org/cl/75930043
Disable it until it's debugged so it doesn't hide other real
problems on Windows. The test was known to be unreliable
anyway (which is why it only needed 1 of 20 runs to pass), but
apparently it never passes on Windows. Figure out why later.
Update #7634
LGTM=alex.brainman
R=adg, alex.brainman
CC=golang-codereviews
https://golang.org/cl/80110043
Change two-bit stack map entries to encode:
0 = dead
1 = scalar
2 = pointer
3 = multiword
If multiword, the two-bit entry for the following word encodes:
0 = string
1 = slice
2 = iface
3 = eface
That way, during stack scanning we can check if a string
is zero length or a slice has zero capacity. We can avoid
following the contained pointer in those cases. It is safe
to do so because it can never be dereferenced, and it is
desirable to do so because it may cause false retention
of the following block in memory.
Slice feature turned off until issue 7564 is fixed.
Update #7549
LGTM=rsc
R=golang-codereviews, bradfitz, rsc
CC=golang-codereviews
https://golang.org/cl/76380043
The existing code did not have a clear notion of whether
memory has been actually reserved. It checked based on
whether in 32-bit mode or 64-bit mode and (on GNU/Linux) the
requested address, but it confused the requested address and
the returned address.
LGTM=rsc
R=rsc, dvyukov
CC=golang-codereviews, michael.hudson
https://golang.org/cl/79610043
This the second part of making persistent HTTPS connections to
certain servers (notably Amazon) robust.
See the story in part 1: https://golang.org/cl/76400046/
This is the http Transport change that notes whether our
net.Conn.Read has ever seen an EOF. If it has, then we use
that as an additional signal to not re-use that connection (in
addition to the HTTP response headers)
Fixes#3514
LGTM=rsc
R=agl, rsc
CC=golang-codereviews
https://golang.org/cl/79240044
Update #3514
An io.Reader is permitted to return either (n, nil)
or (n, io.EOF) on EOF or other error.
The tls package previously always returned (n, nil) for a read
of size n if n bytes were available, not surfacing errors at
the same time.
Amazon's HTTPS frontends like to hang up on clients without
sending the appropriate HTTP headers. (In their defense,
they're allowed to hang up any time, but generally a server
hangs up after a bit of inactivity, not immediately.) In any
case, the Go HTTP client tries to re-use connections by
looking at whether the response headers say to keep the
connection open, and because the connection looks okay, under
heavy load it's possible we'll reuse it immediately, writing
the next request, just as the Transport's always-reading
goroutine returns from tls.Conn.Read and sees (0, io.EOF).
But because Amazon does send an AlertCloseNotify record before
it hangs up on us, and the tls package does its own internal
buffering (up to 1024 bytes) of pending data, we have the
AlertCloseNotify in an unread buffer when our Conn.Read (to
the HTTP Transport code) reads its final bit of data in the
HTTP response body.
This change makes that final Read return (n, io.EOF) when
an AlertCloseNotify record is buffered right after, if we'd
otherwise return (n, nil).
A dependent change in the HTTP code then notes whether a
client connection has seen an io.EOF and uses that as an
additional signal to not reuse a HTTPS connection. With both
changes, the majority of Amazon request failures go
away. Without either one, 10-20 goroutines hitting the S3 API
leads to such an error rate that empirically up to 5 retries
are needed to complete an API call.
LGTM=agl, rsc
R=agl, rsc
CC=golang-codereviews
https://golang.org/cl/76400046
The nproc and ndone fields are uint32. This makes the type
consistent.
LGTM=minux.ma
R=golang-codereviews, minux.ma
CC=golang-codereviews
https://golang.org/cl/79340044
Strictly speaking, it's not necessary in example_test.go, as the
Rows.Close docs say that "If Next returns false, the Rows are closed
automatically". However, if the for loop breaks or returns early, it's
not obvious that you'll leak unless you explicitly call Rows.Close.
LGTM=bradfitz
R=bradfitz
CC=golang-codereviews, rsc
https://golang.org/cl/79330043
Structured Exception Handling (SEH) was the first way to handle
exceptions (memory faults, divides by zero) on Windows.
The S might as well stand for "stack-based": the implementation
interprets stack addresses in a few different ways, and it gets
subtly confused by Go's management of stacks. It's also something
that requires active maintenance during cgo switches, and we've
had bugs in that maintenance in the past.
We have recently come to believe that SEH cannot work with
Go's stack usage. See http://golang.org/issue/7325 for details.
Vectored Exception Handling (VEH) is more like a Unix signal
handler: you set it once for the whole process and forget about it.
This CL drops all the SEH code and replaces it with VEH code.
Many special cases and 7 #ifdefs disappear.
VEH was introduced in Windows XP, so Go on windows/386 will
now require Windows XP or later. The previous requirement was
Windows 2000 or later. Windows 2000 immediately preceded
Windows XP, so Windows 2000 is the only affected version.
Microsoft stopped supporting Windows 2000 in 2010.
See http://golang.org/s/win2000-golang-nuts for details.
Fixes#7325.
LGTM=alex.brainman, r
R=golang-codereviews, alex.brainman, stephen.gutekanst, dave
CC=golang-codereviews, iant, r
https://golang.org/cl/74790043
This has come up twice now. Redirect future questions
to the explanation in the issue tracker.
LGTM=iant, r
R=r, iant
CC=golang-codereviews
https://golang.org/cl/79550043
Currently it's always zero, but that is inconsistent with math.Pow
and also plain wrong.
This is a proposal for how it should be defined.
Fixes#7583.
LGTM=rsc
R=golang-codereviews, iant, gobot, rsc
CC=golang-codereviews
https://golang.org/cl/76940044
ReadFrom should not return until it receives a non-nil error
or too many contiguous (0, nil)s from a given reader.
Currently it immediately returns if it receives one (0, nil).
Fixes#7611.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/76400048
bi is a slice and not an array, so bi[:] does not make much sense.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/79280043
It's a little bit waste to check if r is not a surrogate
code point because RuneError is not a surrogate code point.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/79230043
"min" and "max" in "case '{'" clause are fresh variables.
The variables defined in the outer scope never get value
other than 0.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/78750044
Currently Scan ignores an error returned from source if the number
of bytes source has read is 0.
Fixes#7594.
LGTM=gri
R=golang-codereviews, bradfitz, gri
CC=golang-codereviews
https://golang.org/cl/78120043
Revision 3ae4607a43ff introduced CONVNOP layers
to fix type checking issues arising from comparisons.
The added complexity made 8g run out of registers
when compiling an equality function in go.net/ipv6.
A similar issue occurred in test/sizeof.go on
amd64p32 with 6g.
Fixes#7405.
LGTM=khr
R=rsc, dave, iant, khr
CC=golang-codereviews
https://golang.org/cl/78100044
Encoding.Decode() failed to detect trailing garbages if input contains "==" followed by garbage smaller than 3 bytes (for example, it failed to detect "x" in "AA==x"). This patch fixes the bug and adds a few tests.
LGTM=nigeltao
R=golang-codereviews, bradfitz, nigeltao
CC=golang-codereviews
https://golang.org/cl/75340044
Removes most uses of the REP prefix, which has a high startup cost.
LGTM=iant
R=golang-codereviews, iant, khr
CC=golang-codereviews
https://golang.org/cl/77920043
Rationale:
It already is for scanning.
It is accepted for complexes already, but doesn't work.
It's analogous to %G and %E.
C accepts it too, and we try to be roughly compatible.
Fixes#7518.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/77580044
CL 77580046 caused a data race issue with tests that assumes ReadAt
does not mutate receiver. This patch partially revert CL 77580046
to fix it.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/77900043
These test cases are redundant because TestSimpleFold tests
all possible rotations of test data, so no need to add
rotated strings.
Also updated the comment as it's guaranteed that SimpleFold
returns values in increasing order.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/77730043
UnreadRune should return an error if previous operation is not
ReadRune.
Fixes#7579.
LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/77580046
Also move generated code into a separate file,
because it's difficult to work with the file otherwise.
LGTM=khr
R=golang-codereviews, khr
CC=golang-codereviews
https://golang.org/cl/76080044
A too large float constant is an error.
A too small float constant is rounded to zero.
Fixes#7419
Update #6902
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews
https://golang.org/cl/76730046
