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Commit Graph

2086 Commits

Author SHA1 Message Date
Dmitry Vyukov
b581ca5956 cmd/gc: allow map index expressions in for range statements
Fixes #9691.

Change-Id: I22bfc82e05497e91a7b18a668913aed6c723365d
Reviewed-on: https://go-review.googlesource.com/3282
Reviewed-by: Russ Cox <rsc@golang.org>
2015-01-28 15:14:04 +00:00
Ian Lance Taylor
ec0ebc2281 cmd/gc: treat non-local vars inlined into wrapper as escaping
The compiler has a phase ordering problem.  Escape analysis runs
before wrapper generation.  When a generated wrapper calls a method
defined in a different package, if that call is inlined, there will be
no escape information for the variables defined in the inlined call.
Those variables will be placed on the stack, which fails if they
actually do escape.

There are probably various complex ways to fix this.  This is a simple
way to avoid it: when a generated wrapper calls a method defined in a
different package, treat all local variables as escaping.

Fixes #9537.

Change-Id: I530f39346de16ad173371c6c3f69cc189351a4e9
Reviewed-on: https://go-review.googlesource.com/3092
Reviewed-by: Russ Cox <rsc@golang.org>
2015-01-22 03:25:12 +00:00
Chris Manghane
f5b8813e93 cmd/gc: don't unpack struct arguments to append
Fixes #9634.

Change-Id: I7b18f26c2fb812978fc7adc5bfd39ebfffe48701
Reviewed-on: https://go-review.googlesource.com/3080
Reviewed-by: Minux Ma <minux@golang.org>
2015-01-20 22:55:56 +00:00
Keith Randall
c3b459d328 test: generate tests for arithmetic on narrow types
Fixes #9607
Related to #9604
Inadvertently found #9609

Change-Id: I8a8ddf84ac72d3e18986fd8e9288734459f3f174
Reviewed-on: https://go-review.googlesource.com/2962
Reviewed-by: Minux Ma <minux@golang.org>
2015-01-17 21:00:15 +00:00
Keith Randall
daa64ddfe6 cmd/5g: make sure we normalize after unary ops on small types
We were failing ^uint16(0xffff) == 0, as we computed 0xffff0000 instead.

I could only trigger a failure for the above case, the other two tests
^uint16(0xfffe) == 1 and -uint16(0xffff) == 1 didn't seem to fail
previously.  Somehow they get MOVHUs inserted for other reasons (used
by CMP instead of TST?).  I fixed OMINUS anyway, better safe than
sorry.

Fixes #9604

Change-Id: I4c2d5bdc667742873ac029fdbe3db0cf12893c27
Reviewed-on: https://go-review.googlesource.com/2940
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
2015-01-15 23:50:01 +00:00
Rob Pike
3b63b69d2f test: comment the behavior and use of cmplxdivide*
The various files are confusingly named and their operation
not easy to see. Add a comment to cmplxdivide.c, one of the few
C files that will endure in the repository, to explain how to build
and run the test.

Change-Id: I1fd5c564a14217e1b9815b09bc24cc43c54c096f
Reviewed-on: https://go-review.googlesource.com/2850
Reviewed-by: Russ Cox <rsc@golang.org>
2015-01-15 00:00:06 +00:00
Shenghou Ma
fcff3ba740 cmd/gc: don't recurse infinitely when a recursive type references itself more than once
Fixes #9432

Change-Id: I08c92481afa7c7fac890aa780efc1cb2fabad528
Reviewed-on: https://go-review.googlesource.com/2115
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Russ Cox <rsc@golang.org>
2015-01-12 02:09:50 +00:00
Josh Bleecher Snyder
f03c9202c4 cmd/gc: optimize memclr of slices and arrays
Recognize loops of the form

for i := range a {
	a[i] = zero
}

in which the evaluation of a is free from side effects.
Replace these loops with calls to memclr.
This occurs in the stdlib in 18 places.

The motivating example is clearing a byte slice:

benchmark                old ns/op     new ns/op     delta
BenchmarkGoMemclr5       3.31          3.26          -1.51%
BenchmarkGoMemclr16      13.7          3.28          -76.06%
BenchmarkGoMemclr64      50.8          4.14          -91.85%
BenchmarkGoMemclr256     157           6.02          -96.17%

Update #5373.

Change-Id: I99d3e6f5f268e8c6499b7e661df46403e5eb83e4
Reviewed-on: https://go-review.googlesource.com/2520
Reviewed-by: Keith Randall <khr@golang.org>
2015-01-09 22:35:25 +00:00
Rick Hudson
db7fd1c142 runtime: increase GC concurrency.
run GC in its own background goroutine making the
caller runnable if resources are available. This is
critical in single goroutine applications.
Allow goroutines that allocate a lot to help out
the GC and in doing so throttle their own allocation.
Adjust test so that it only detects that a GC is run
during init calls and not whether the GC is memory
efficient. Memory efficiency work will happen later
in 1.5.

Change-Id: I4306f5e377bb47c69bda1aedba66164f12b20c2b
Reviewed-on: https://go-review.googlesource.com/2349
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
2015-01-08 20:34:56 +00:00
Keith Randall
fcfbeb3adf test: shorten test runtime
This test was taking a long time, reduce its zealousness.

Change-Id: Ib824247b84b0039a9ec690f72336bef3738d4c44
Reviewed-on: https://go-review.googlesource.com/2502
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Minux Ma <minux@golang.org>
2015-01-08 04:49:43 +00:00
Josh Bleecher Snyder
43e6923131 cmd/gc: optimize existence-only map lookups
The compiler converts 'val, ok = m[key]' to

        tmp, ok = <runtime call>
        val = *tmp

For lookups of the form '_, ok = m[key]',
the second statement is unnecessary.
By not generating it we save a nil check.

Change-Id: I21346cc195cb3c62e041af8b18770c0940358695
Reviewed-on: https://go-review.googlesource.com/1975
Reviewed-by: Russ Cox <rsc@golang.org>
2015-01-07 22:36:06 +00:00
Josh Bleecher Snyder
60801c4853 test: delete testlib
It is unused as of e7173dfd.

Change-Id: I3e4ea3fc66cf0a768ff28172a151b244952eefc9
Reviewed-on: https://go-review.googlesource.com/2093
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2015-01-07 21:48:48 +00:00
Matthew Dempsky
537ddc9456 runtime: fix slicecopy return value for zero-width elements
Fixes #8620

Change-Id: Idb49e586919d21d07e94a39ed9ebb0562f403460
Reviewed-on: https://go-review.googlesource.com/2221
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-01-04 01:59:59 +00:00
Josh Bleecher Snyder
8bbd80063b cmd/go: put user ldflags at the end of the linker invocation
If the user provided a key but no value via -ldflag -X,
another linker flag was used as the value.

Placing the user's flags at the end avoids this problem.
It also provides the user the opportunity to
override existing linker flags.

Fixes #8810.

Change-Id: I96f4190713dc9a9c29142e56658446fba7fb6bc8
Reviewed-on: https://go-review.googlesource.com/2242
Reviewed-by: Minux Ma <minux@golang.org>
2015-01-02 18:36:44 +00:00
Shenghou Ma
cb1897a58c cmd/gc: give an error if only one argument is given to complex()
Fixes #8501

Change-Id: I0dbbdded7f7924351c3d1841d60cb5c934b295b7
Reviewed-on: https://go-review.googlesource.com/2143
Reviewed-by: Chris Manghane <cmang@golang.org>
2015-01-02 02:52:56 +00:00
Chris Manghane
5cc29ab95e cmd/gc: logical operators should produce untyped bool for untyped
operands

Fixes #6671 for cmd/gc.

Change-Id: I4907655b6e243960f2ceb544c63ea16513c7bd68
Reviewed-on: https://go-review.googlesource.com/1251
Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-29 23:36:30 +00:00
Chris Manghane
edf7258416 test: add fixed GoSmith bugs reported on the gcc Bugzilla
Change-Id: I36b57f3e299a4f96b8b5aa55c9c224d888229684
Reviewed-on: https://go-review.googlesource.com/1790
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2014-12-29 23:21:10 +00:00
Shenghou Ma
958e0792b5 test/fixedbugs/issue9355: fix build on arm and power64
Change-Id: I1ef770184ad1d42bcb58714d559f2cc866a919ab
Signed-off-by: Shenghou Ma <minux@golang.org>
Reviewed-on: https://go-review.googlesource.com/1880
Reviewed-by: Keith Randall <khr@golang.org>
2014-12-24 00:07:46 +00:00
David du Colombier
fbdf59a7c4 test: disable bug248 and bug345 tests on Plan 9
These tests were enabled as part of change 1774.
They depend on the errchk tool, which is a Perl
script. However, Perl is not available on Plan 9.

Change-Id: I82707aae16013acc9a3800d39b0084588b852b53
Reviewed-on: https://go-review.googlesource.com/2031
Reviewed-by: Minux Ma <minux@golang.org>
2014-12-23 10:28:39 +00:00
Josh Bleecher Snyder
209dd4cdc1 test: fix windows build
Broken by e7173dfdfd

Fix by simply disabling the relevant tests.

* bug248 and bug345 require errchk, but we can't
  rely on perl being available.
* bug369 is disabled anyway.

Change-Id: Idf73ebccb066943e3fe17c2f662b37238ec74dfe
Reviewed-on: https://go-review.googlesource.com/2052
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
2014-12-23 01:12:30 +00:00
Ian Lance Taylor
02f56bfb5c test: add test case that gccgo failed to link
Gccgo creates a struct to hold the arguments for the deferred
function.  In this example the struct holds a type defined in a
different package.  The bug was that gccgo tried to create an equality
function for this struct, and it implemented that function by calling
the equality function for the type defined in the other package.
Since that type is not exported, the reference to the equality
function failed at link time.  Normally it is impossible for a struct
to directly contain a member that is an unexported type from another
package, but in this specific case it was possible.  Fixed in gccgo
with https://codereview.appspot.com/183500043 .

Change-Id: I8ec3a33631225b9ac2a4ac060cb4d10b4635e60b
Reviewed-on: https://go-review.googlesource.com/1690
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
2014-12-22 23:07:10 +00:00
Josh Bleecher Snyder
e7173dfdfd test: migrate remaining tests to run.go
* bug248, bug345, bug369, and bug429 were ported from bash commands to run scripts. bug369 remains disabled.
* bug395 is a test for issue 1909, which is still open. It is marked as skip now and will be usable with compile with run.go when issue 1909 is fixed.

Fixes #4139

Updates #1909

Change-Id: Ibb5fbfb5cf72ddc285829245318eeacd3fb5a636
Reviewed-on: https://go-review.googlesource.com/1774
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-22 22:41:34 +00:00
Shenghou Ma
c5089a7a81 test/fixedbugs/issue9355: fix build on windows and skip on nacl
Change-Id: If367cc1e8c2d744569513bc71da6e6c454c74e9a
Signed-off-by: Shenghou Ma <minux@golang.org>
Reviewed-on: https://go-review.googlesource.com/1802
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>
2014-12-19 01:06:33 +00:00
Keith Randall
2fc29a83ae cmd/gc: resolve static addresses of the form &x.f at link time
When we do y = &x for global variables x and y, y gets initialized
at link time.  Do the same for y = &x.f if x is a struct and y=&x[5]
if x is an array.

fixes #9217
fixes #9355

Change-Id: Iea3c0ce2ce1b309e2b760e345608fd95460b5713
Reviewed-on: https://go-review.googlesource.com/1691
Reviewed-by: Minux Ma <minux@golang.org>
2014-12-18 21:53:03 +00:00
Josh Bleecher Snyder
8e0686a071 test: add missing linkx test
This test was added in CL 151000043.
It got lost in CL 144630044.

Change-Id: I318ab11be8e3e7489fc1395457c029c8bdb2aa41
Reviewed-on: https://go-review.googlesource.com/1773
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2014-12-18 17:41:27 +00:00
Ian Lance Taylor
6cd4d59db6 test: add bug494: test case miscompiled by gccgo
Gccgo incorrectly executed functions multiple times when they appeared
in a composite literal that required a conversion between different
interface types.

Change-Id: I7b40e76ed23fa8440ffa03b262041265c109adf7
Reviewed-on: https://go-review.googlesource.com/1710
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Minux Ma <minux@golang.org>
2014-12-18 02:45:00 +00:00
Ian Lance Taylor
60ea2c594b test: add test that gccgo failed to compile
Gccgo failed to create the type descriptor for the type used to
allocate the nil value passed to append as the second argument when
append is called with only one argument.  Calling append with only one
argument is unusual but obviously should not cause a compiler crash.

Change-Id: I530821847dfd68f0302de6ca6a84dfbc79653935
Reviewed-on: https://go-review.googlesource.com/1692
Reviewed-by: Minux Ma <minux@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2014-12-17 02:22:57 +00:00
Keith Randall
50bc3d5bbc runtime: fix deadlock in runtime.Stack
It shouldn't semacquire() inside an acquirem(), the runtime
thinks that means deadlock.  It actually isn't a deadlock, but it
looks like it because acquirem() does m.locks++.

Candidate for inclusion in 1.4.1.  runtime.Stack with all=true
is pretty unuseable in GOMAXPROCS>1 environment.

fixes #9321

Change-Id: Iac6b664217d24763b9878c20e49229a1ecffc805
Reviewed-on: https://go-review.googlesource.com/1600
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
2014-12-16 17:04:45 +00:00
Shenghou Ma
e8f13700b7 test/fixedbugs/bug302: fix test on windows.
Change-Id: I74c2578d1620b37a6486eca00a774b9a736a8899
Reviewed-on: https://go-review.googlesource.com/1222
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2014-12-09 05:23:35 +00:00
Ian Lance Taylor
c5de72b213 test: write Go wrapper code so that bug302 can be run by run.go
Issue #4139.

Change-Id: I50d85a65b22c0cfb4d2a078cee45cf7adb23ba77
Reviewed-on: https://go-review.googlesource.com/1210
Reviewed-by: Russ Cox <rsc@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
2014-12-09 01:07:27 +00:00
Robert Griesemer
779682107f Fix whitespace (use blanks consistently).
Change-Id: I73ecfe8f1e46e4821dafc6ed5788f48a1f0deeea
Reviewed-on: https://go-review.googlesource.com/1213
Reviewed-by: Alan Donovan <adonovan@google.com>
2014-12-08 22:22:58 +00:00
Keith Randall
212914f573 runtime: test for linear enqueue/dequeue behavior
Make sure dequeueing from a channel queue does not exhibit quadratic time behavior.

Change-Id: Ifb7c709b026f74c7e783610d4914dd92909a441b
Reviewed-on: https://go-review.googlesource.com/1212
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-08 22:18:17 +00:00
Robert Griesemer
8d5fe682b0 test/fibo: a stand-alone bignum/allocation benchmark and test
Usage:
fibo <n>        compute fibonacci(n), n must be >= 0
fibo -bench     benchmark fibonacci computation (takes about 1 min)

Additional flags:
-half           add values using two half-digit additions
-opt            optimize memory allocation through reuse
-short          only print the first 10 digits of very large fibonacci numbers

This change was reviewed in detail as https://codereview.appspot.com/168480043 .

Change-Id: I7c86d49c5508532ea6206d00f424cf2117d2fe41
Reviewed-on: https://go-review.googlesource.com/1211
Reviewed-by: Russ Cox <rsc@golang.org>
2014-12-08 20:57:31 +00:00
Russ Cox
31457cef6d all: merge dev.garbage (d1238958d4ae) into default branch
When we start work on Gerrit, ppc64 and garbage collection
work will continue in the master branch, not the dev branches.

(We may still use dev branches for other things later, but
these are ready to be merged, and doing it now, before moving
to Git means we don't have to have dev branches working
in the Gerrit workflow on day one.)

TBR=rlh
CC=golang-codereviews
https://golang.org/cl/183140043
2014-12-05 20:34:45 -05:00
Russ Cox
db40624110 [dev.garbage] runtime: raise StackGuard limit for Windows (again)
640 bytes ought to be enough for anybody.

We'll bring this back down before Go 1.5. That's issue 9214.

TBR=rlh
CC=golang-codereviews
https://golang.org/cl/188730043
2014-12-05 19:50:09 -05:00
Russ Cox
09d92b6bbf all: power64 is now ppc64
Fixes #8654.

LGTM=austin
R=austin
CC=golang-codereviews
https://golang.org/cl/180600043
2014-12-05 19:13:20 -05:00
Russ Cox
b8540fc288 [dev.garbage] all: merge dev.cc (493ad916c3b1) into dev.garbage
TBR=austin
CC=golang-codereviews
https://golang.org/cl/179290043
2014-11-24 12:07:11 -05:00
Russ Cox
50e0749f87 [dev.cc] all: merge default (e4ab8f908aac) into dev.cc
TBR=austin
CC=golang-codereviews
https://golang.org/cl/179040044
2014-11-20 11:48:08 -05:00
Russ Cox
b3932baba4 runtime: fix sudog leak
The SudoG used to sit on the stack, so it was cheap to allocated
and didn't need to be cleaned up when finished.

For the conversion to Go, we had to move sudog off the stack
for a few reasons, so we added a cache of recently used sudogs
to keep allocation cheap. But we didn't add any of the necessary
cleanup before adding a SudoG to the new cache, and so the cached
SudoGs had stale pointers inside them that have caused all sorts
of awful, hard to debug problems.

CL 155760043 made sure SudoG.elem is cleaned up.
CL 150520043 made sure SudoG.selectdone is cleaned up.

This CL makes sure SudoG.next, SudoG.prev, and SudoG.waitlink
are cleaned up. I should have done this when I did the other two
fields; instead I wasted a week tracking down a leak they caused.

A dangling SudoG.waitlink can point into a sudogcache list that
has been "forgotten" in order to let the GC collect it, but that
dangling .waitlink keeps the list from being collected.
And then the list holding the SudoG with the dangling waitlink
can find itself in the same situation, and so on. We end up
with lists of lists of unusable SudoGs that are still linked into
the object graph and never collected (given the right mix of
non-trivial selects and non-channel synchronization).

More details in golang.org/issue/9110.

Fixes #9110.

LGTM=r
R=r
CC=dvyukov, golang-codereviews, iant, khr
https://golang.org/cl/177870043
2014-11-16 16:44:45 -05:00
Russ Cox
3e804631d9 [dev.cc] all: merge dev.power64 (7667e41f3ced) into dev.cc
This is to reduce the delta between dev.cc and dev.garbage to just garbage collector changes.

These are the files that had merge conflicts and have been edited by hand:
        malloc.go
        mem_linux.go
        mgc.go
        os1_linux.go
        proc1.go
        panic1.go
        runtime1.go

LGTM=austin
R=austin
CC=golang-codereviews
https://golang.org/cl/174180043
2014-11-14 12:10:52 -05:00
Russ Cox
9ef4e56108 [dev.garbage] all: merge dev.power64 (7667e41f3ced) into dev.garbage
Now the only difference between dev.cc and dev.garbage
is the runtime conversion on the one side and the
garbage collection on the other. They both have the
same set of changes from default and dev.power64.

LGTM=austin
R=austin
CC=golang-codereviews
https://golang.org/cl/172570043
2014-11-14 12:09:42 -05:00
Russ Cox
3dcc62e1da [dev.garbage] all: merge default (f38460037b72) into dev.garbage
This is the revision that dev.cc is branched from.

LGTM=austin
R=austin
CC=golang-codereviews
https://golang.org/cl/169590043
2014-11-14 11:37:54 -05:00
Russ Cox
c99616fc67 test: fix nacl build
Disable linkx_run.go and sinit_run.go, because they
exec subprocesses, which NaCl cannot.

TBR=r
CC=golang-codereviews
https://golang.org/cl/171350043
2014-11-09 21:10:49 -05:00
Josh Bleecher Snyder
9b5444420c test: move linkx and sinit to run.go
The remaining run-only tests will be migrated to run.go in another CL.

This CL will break the build due to issues 8746 and 8806.

Update #4139
Update #8746
Update #8806

LGTM=rsc
R=rsc, bradfitz, iant
CC=golang-codereviews
https://golang.org/cl/144630044
2014-11-06 15:14:08 -05:00
Russ Cox
75d3f62b3c [dev.garbage] cmd/gc, runtime: add locks around print statements
Now each C printf, Go print, or Go println is guaranteed
not to be interleaved with other calls of those functions.
This should help when debugging concurrent failures.

LGTM=rlh
R=rlh
CC=golang-codereviews
https://golang.org/cl/169120043
2014-11-05 14:42:54 -05:00
Ian Lance Taylor
c6e53fea10 test: comment out failing cases from sinit.go
One failing case this removes is:

var bytes = []byte("hello, world")
var copy_bytes = bytes

We could handle this in the compiler, but it requires special
case for a variable that is initialized to the value of a
variable that is initialized to a string literal converted to
[]byte.  This seems an unlikely case--it never occurs in the
standrd library--and it seems unnecessary to write the code to
handle it.

If we do want to support this case, one approach is
https://golang.org/cl/171840043.

The other failing cases are of the form

var bx bool
var copy_bx = bx

The compiler used to initialize copy_bx to false.  However,
that led to issue 7665, since bx may be initialized in non-Go
code.  The compiler no longer assumes that bx must be false,
so copy_bx can not be statically initialized.

We can fix these with https://golang.org/cl/169040043
if we also pass -complete to the compiler as part of this
test.  This is OK but it's too late in the release cycle.

Fixes #8746.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/165400043
2014-11-04 10:20:35 -08:00
Austin Clements
a5e1e1599c [dev.power64] test: "fix" live.go test on power64x
On power64x, this one line in live.go reports that t is live
because of missing optimization passes.  This isn't what this
test is trying to test, so shuffle bad40 so that it still
accomplishes the intent of the test without also depending on
optimization.

LGTM=rsc
R=rsc, dave
CC=golang-codereviews
https://golang.org/cl/167110043
2014-11-03 17:25:36 -05:00
Austin Clements
d10a115ef9 [dev.power64] test: disable nilptr3 test on power64x
The remaining failures in this test are because of incomplete
optimization support on power64x.  Tracked in issue 9058.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/168130043
2014-11-03 17:25:03 -05:00
Austin Clements
31b1207fde [dev.power64] all: merge default into dev.power64
Trivial merge except for src/runtime/asm_power64x.s and
src/runtime/signal_power64x.c

LGTM=rsc
R=rsc
CC=golang-codereviews
https://golang.org/cl/168950044
2014-11-03 10:53:11 -05:00
Austin Clements
6e86003651 [dev.power64] 9g: fix under-zeroing in clearfat
All three cases of clearfat were wrong on power64x.

The cases that handle 1032 bytes and up and 32 bytes and up
both use MOVDU (one directly generated in a loop and the other
via duffzero), which leaves the pointer register pointing at
the *last written* address.  The generated code was not
accounting for this, so the byte fill loop was re-zeroing the
last zeroed dword, rather than the bytes following the last
zeroed dword.  Fix this by simply adding an additional 8 byte
offset to the byte zeroing loop.

The case that handled under 32 bytes was also wrong.  It
didn't update the pointer register at all, so the byte zeroing
loop was simply re-zeroing the beginning of region.  Again,
the fix is to add an offset to the byte zeroing loop to
account for this.

LGTM=dave, bradfitz
R=rsc, dave, bradfitz
CC=golang-codereviews
https://golang.org/cl/168870043
2014-10-31 11:08:27 -04:00