Nigel Tao [Thu, 19 Jun 2014 01:39:03 +0000 (11:39 +1000)]
image/jpeg: use a look-up table to speed up Huffman decoding. This
requires a decoder to do its own byte buffering instead of using
bufio.Reader, due to byte stuffing.
benchmark old MB/s new MB/s speedup
BenchmarkDecodeBaseline 33.40 50.65 1.52x
BenchmarkDecodeProgressive 24.34 31.92 1.31x
On 6g, unsafe.Sizeof(huffman{}) falls from 4872 to 964 bytes, and
the decoder struct contains 8 of those.
Rob Pike [Wed, 18 Jun 2014 17:57:18 +0000 (10:57 -0700)]
fmt: include ±Inf and NaN in the complex format test
Just to be more thorough.
No need to push this to 1.3; it's just a test change that
worked without any changes to the code being tested.
Rui Ueyama [Wed, 18 Jun 2014 05:08:46 +0000 (22:08 -0700)]
strings: add fast path to Replace
genericReplacer.lookup is called for each byte of an input
string. In many (most?) cases, lookup will fail for the first
byte, and it will return immediately. Adding a fast path for
that case seems worth it.
Rob Pike [Tue, 17 Jun 2014 21:56:54 +0000 (14:56 -0700)]
fmt: fix signs when zero padding.
Bug was introduced recently. Add more tests, fix the bugs.
Suppress + sign when not required in zero padding.
Do not zero pad infinities.
All old tests still pass.
This time for sure!
Fixes #8217.
Dominik Honnef [Tue, 17 Jun 2014 18:43:35 +0000 (14:43 -0400)]
misc/emacs: replace hacky go--delete-whole-line with own implementation
Using flet to replace kill-region with delete-region was a hack,
flet is now (GNU Emacs 24.3) deprecated and at least two people
have reported an issue where using go--delete-whole-line would
permanently break their kill ring. While that issue is probably
caused by faulty third party code (possibly prelude), it's easier
to write a clean implementation than to tweak the hack.
Generating shorter functions improves compilation time. On my laptop, this test's running time goes from 5.5s to 1.5s; the wall clock time to run all tests goes down 1s. On Raspberry Pi, this CL cuts 50s off the wall clock time to run all tests.
Rob Pike [Mon, 16 Jun 2014 17:45:05 +0000 (10:45 -0700)]
fmt: don't put 0x on every byte of a compact hex-encoded string
Printf("%x", "abc") was "0x610x620x63"; is now "0x616263", which
is surely better.
Printf("% #x", "abc") is still "0x61 0x62 0x63".
Russ Cox [Fri, 13 Jun 2014 01:12:53 +0000 (21:12 -0400)]
runtime: revise CL 105140044 (defer nil) to work on Windows
It appears that something about Go on Windows
cannot handle the fault cause by a jump to address 0.
The way Go represents and calls functions, this
never happened at all, until CL 105140044.
This CL changes the code added in CL 105140044
to make jump to 0 impossible once again.
Fixes #8047. (again, on Windows)
TBR=bradfitz
R=golang-codereviews, dave
CC=adg, golang-codereviews, iant, r
https://golang.org/cl/105120044
Russ Cox [Thu, 12 Jun 2014 20:34:54 +0000 (16:34 -0400)]
runtime: do not trace past jmpdefer during pprof traceback on arm
jmpdefer modifies PC, SP, and LR, and not atomically,
so walking past jmpdefer will often end up in a state
where the three are not a consistent execution snapshot.
This was causing warning messages a few frames later
when the traceback realized it was confused, but given
the right memory it could easily crash instead.
Update #8153
LGTM=minux, iant
R=golang-codereviews, minux, iant
CC=golang-codereviews, r
https://golang.org/cl/107970043
Rob Pike [Thu, 12 Jun 2014 18:44:55 +0000 (11:44 -0700)]
time: avoid broken fix for buggy TestOverflowRuntimeTimer
The test requires that timerproc runs, but busy loops and starves
the scheduler so that, with high probability, timerproc doesn't run.
Avoid the issue by expecting the test to succeed; if not, a major
outside timeout will kill it and let us know.
As you can see from the diffs, there have been several attempts to
fix this with chicanery, but none has worked. Don't bother trying
any more.
Rui Ueyama [Wed, 11 Jun 2014 18:22:08 +0000 (11:22 -0700)]
encoding/base64, encoding/base32: make DecodeString faster
Previously, an input string was stripped of newline
characters at the beginning of DecodeString and then passed
to Decode. Decode again tried to strip newline characters.
That's waste of time.
benchmark old MB/s new MB/s speedup
BenchmarkDecodeString 38.37 65.20 1.70x
Russ Cox [Wed, 11 Jun 2014 18:21:06 +0000 (14:21 -0400)]
cmd/gc: fix &result escaping into result
There is a hierarchy of location defined by loop depth:
-1 = the heap
0 = function results
1 = local variables (and parameters)
2 = local variable declared inside a loop
3 = local variable declared inside a loop inside a loop
etc
In general if an address from loopdepth n is assigned to
something in loop depth m < n, that indicates an extended
lifetime of some form that requires a heap allocation.
Function results can be local variables too, though, and so
they don't actually fit into the hierarchy very well.
Treat the address of a function result as level 1 so that
if it is written back into a result, the address is treated
as escaping.
Russ Cox [Wed, 11 Jun 2014 15:48:47 +0000 (11:48 -0400)]
cmd/gc: fix escape analysis for &x inside switch x := v.(type)
The analysis for &x was using the loop depth on x set
during x's declaration. A type switch creates a list of
implicit declarations that were not getting initialized
with loop depths.
Ian Lance Taylor [Tue, 10 Jun 2014 21:11:39 +0000 (14:11 -0700)]
cmd/ld: fix PC deltas in DWARF line number table
The putpclcdelta function set the DWARF line number PC to
s->value + pcline->pc, which is correct, but the code then set
the local variable pc to epc, which can be a different value.
This caused the next delta in the DWARF table to be wrong.
Russ Cox [Fri, 6 Jun 2014 20:52:14 +0000 (16:52 -0400)]
runtime: fix panic stack during runtime.Goexit during panic
A runtime.Goexit during a panic-invoked deferred call
left the panic stack intact even though all the stack frames
are gone when the goroutine is torn down.
The next goroutine to reuse that struct will have a
bogus panic stack and can cause the traceback routines
to walk into garbage.
Most likely to happen during tests, because t.Fatal might
be called during a deferred func and uses runtime.Goexit.
This "not enough cleared in Goexit" failure mode has
happened to us multiple times now. Clear all the pointers
that don't make sense to keep, not just gp->panic.
Russ Cox [Thu, 5 Jun 2014 20:40:23 +0000 (16:40 -0400)]
cmd/6g: fix stack zeroing on native client
I am not sure what the rounding here was
trying to do, but it was skipping the first
pointer on native client.
The code above the rounding already checks
that xoffset is widthptr-aligned, so the rnd
was a no-op everywhere but on Native Client.
And on Native Client it was wrong.
Perhaps it was supposed to be rounding down,
not up, but zerorange handles the extra 32 bits
correctly, so the rnd does not seem to be necessary
at all.
This wouldn't be worth doing for Go 1.3 except
that it can affect code on the playground.
Dmitriy Vyukov [Thu, 5 Jun 2014 17:08:28 +0000 (21:08 +0400)]
doc: fix happens-before rules for buffered channels
The current wording is reversed in 2 places.
Not sure how it got 4 LGTMs (mine was there as well).
Update #6242.
Russ Cox [Tue, 3 Jun 2014 15:35:59 +0000 (11:35 -0400)]
cmd/gc: fix escape analysis of func returning indirect of parameter
I introduced this bug when I changed the escape
analysis to run in phases based on call graph
dependency order, in order to be more precise about
inputs escaping back to outputs (functions returning
their arguments).
Given
func f(z **int) *int { return *z }
we were tagging the function as 'z does not escape
and is not returned', which is all true, but not
enough information.
If used as:
var x int
p := &x
q := &p
leak(f(q))
then the compiler might try to keep x, p, and q all
on the stack, since (according to the recorded
information) nothing interesting ends up being
passed to leak.
In fact since f returns *q = p, &x is passed to leak
and x needs to be heap allocated.
To trigger the bug, you need a chain that the
compiler wants to keep on the stack (like x, p, q
above), and you need a function that returns an
indirect of its argument, and you need to pass the
head of the chain to that function. This doesn't
come up very often: this bug has been present since
June 2012 (between Go 1 and Go 1.1) and we haven't
seen it until now. It helps that most functions that
return indirects are getters that are simple enough
to be inlined, avoiding the bug.
Earlier versions of Go also had the benefit that if
&x really wasn't used beyond x's lifetime, nothing
broke if you put &x in a heap-allocated structure
accidentally. With the new stack copying, though,
heap-allocated structures containing &x are not
updated when the stack is copied and x moves,
leading to crashes in Go 1.3 that were not crashes
in Go 1.2 or Go 1.1.
The fix is in two parts.
First, in the analysis of a function, recognize when
a value obtained via indirect of a parameter ends up
being returned. Mark those parameters as having
content escape back to the return results (but we
don't bother to write down which result).
Second, when using the analysis to analyze, say,
f(q), mark parameters with content escaping as
having any indirections escape to the heap. (We
don't bother trying to match the content to the
return value.)
The fix could be less precise (simpler).
In the first part we might mark all content-escaping
parameters as plain escaping, and then the second
part could be dropped. Or we might assume that when
calling f(q) all the things pointed at by q escape
always (for any f and q).
The fix could also be more precise (more complex).
We might record the specific mapping from parameter
to result along with the number of indirects from the
parameter to the thing being returned as the result,
and then at the call sites we could set up exactly the
right graph for the called function. That would make
notleaks(f(q)) be able to keep x on the stack, because
the reuslt of f(q) isn't passed to anything that leaks it.
The less precise the fix, the more stack allocations
become heap allocations.
This fix is exactly as precise as it needs to be so that
none of the current stack allocations in the standard
library turn into heap allocations.
Fixes #8120.
LGTM=iant
R=golang-codereviews, iant
CC=golang-codereviews, khr, r
https://golang.org/cl/102040046
Russ Cox [Tue, 3 Jun 2014 01:06:30 +0000 (21:06 -0400)]
runtime: fix 1-byte return during x.(T) for 0-byte T
The 1-byte write was silently clearing a byte on the stack.
If there was another function call with more arguments
in the same stack frame, no harm done.
Otherwise, if the variable at that location was already zero,
no harm done.
Otherwise, problems.
Fixes #8139.
LGTM=dsymonds
R=golang-codereviews, dsymonds
CC=golang-codereviews, iant, r
https://golang.org/cl/100940043
Rob Pike [Mon, 2 Jun 2014 23:01:53 +0000 (16:01 -0700)]
cmd/gc: don't generate zillions of linehists for wrapper functions
This is a workaround - the code should be better than this - but the
fix avoids generating large numbers of linehist entries for the wrapper
functions that enable interface conversions. There can be many of
them, they all happen at the end of compilation, and they can all
share a linehist entry.
Avoids bad n^2 behavior in liblink.
Test case in issue 8135 goes from 64 seconds to 2.5 seconds (still bad
but not intolerable).
Andrew Gerrand [Sun, 1 Jun 2014 22:48:20 +0000 (08:48 +1000)]
cmd/dist: only use beta tag in version string for the exact revision
Right now, any revision on the default branch after go1.3beta2 is
described by "go verson" as go1.3beta2 plus some revision.
That's OK for now, but once go1.3 is released, that will seem wrong.
Andrew Gerrand [Sun, 1 Jun 2014 22:34:26 +0000 (08:34 +1000)]
misc/goplay: remove program
This program has barely been touched since it was first committed,
and in its current state it opens a code execution vector similar
to the one that was recently fixed in go.tools/playground/socket.
Russ Cox [Sun, 1 Jun 2014 17:57:46 +0000 (13:57 -0400)]
runtime: fix correctness test at end of traceback
We were requiring that the defer stack and the panic stack
be completely processed, thinking that if any were left over
the stack scan and the defer stack/panic stack must be out
of sync. It turns out that the panic stack may well have
leftover entries in some situations, and that's okay.
Fixes #8132.
LGTM=minux, r
R=golang-codereviews, minux, r
CC=golang-codereviews, iant, khr
https://golang.org/cl/100900044