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Commit Graph

22948 Commits

Author SHA1 Message Date
Austin Clements
69001e404e runtime: fix freed page accounting in mHeap_ReclaimList
mHeap_ReclaimList is asked to reclaim at least npages pages, but it
counts the number of spans reclaimed, not the number of pages
reclaimed. The number of spans reclaimed is strictly larger than the
number of pages, so this is not strictly wrong, but it is forcing more
reclamation than was intended by the caller, which delays large
allocations.

Fix this by increasing the count by the number of pages in the swept
span, rather than just increasing it by 1.

Fixes #9048.

Change-Id: I5ae364a9837a6012e68fcd431bba000340cfd50c
Reviewed-on: https://go-review.googlesource.com/8920
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Rick Hudson <rlh@golang.org>
2015-04-14 20:55:14 +00:00
Austin Clements
bedb6f8aef runtime: remove unnecessary traceNextGC
Commit d7e0ad4 removed the next_gc manipulation from mSpan_Sweep, but
left in the traceNextGC() for recording the updated next_gc
value. Remove this now unnecessary call.

Change-Id: I28e0de071661199be9810d7bdcc81ce50b5a58ae
Reviewed-on: https://go-review.googlesource.com/8894
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Rick Hudson <rlh@golang.org>
2015-04-14 20:54:23 +00:00
Marius Nuennerich
21e37daa49 io/ioutil: fix locking of the tempfile random state
Fixes #10451

Change-Id: I15ed777e9a4a4e1ba1178d07fcbe0ab4bf0d9e50
Reviewed-on: https://go-review.googlesource.com/8936
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2015-04-14 19:45:05 +00:00
Matthew Dempsky
eced964c2d reflect: document reflect.TypeOf((*Foo)(nil)).Elem() idiom
See also golang-dev discussion:
https://groups.google.com/d/msg/golang-dev/Nk9gnTINlTg/SV8rBt-2__kJ

Change-Id: I49edd98d73400c1757b6085dec86752de569c01a
Reviewed-on: https://go-review.googlesource.com/8923
Reviewed-by: Rob Pike <r@golang.org>
2015-04-14 17:19:36 +00:00
Rob Pike
eba38fd780 cmd/go: do not cover package unsafe
Even if requested, there is no .go file for unsafe - it comes from the
compiler - so referencing its cover variables will break the compilation
in a command like
	go test -coverpkg=all fmt

Fixes #10408.

Change-Id: If92658ef6c29dc020f66ba30b02eaa796f7205e0
Reviewed-on: https://go-review.googlesource.com/8891
Reviewed-by: Russ Cox <rsc@golang.org>
2015-04-14 17:07:34 +00:00
Dmitry Vyukov
24f246c1b6 cmd/gc: fix crash during escape analysis
Fixes #10441

Compiler crashed as:

panic: runtime error: invalid memory address or nil pointer dereference
goroutine 1 [running]:
cmd/internal/gc.haspointers(0x0, 0xffffffffffffffff)
    src/cmd/internal/gc/reflect.go:623 +0x1f
cmd/internal/gc.escwalk(0x20c82dc00, 0xffffffffffffffff, 0x20c82dda0, 0x20c835520)
    src/cmd/internal/gc/esc.go:1291 +0x14aa
cmd/internal/gc.escwalk(0x20c82dc00, 0xffffffffffffffff, 0x20c82dda0, 0x20beac340)
    src/cmd/internal/gc/esc.go:1386 +0x836

while evaluating haspointers of the fake OADDR node here:

	leaks = level <= 0 && dst.Escloopdepth < src.Escloopdepth || level < 0 && dst == &e.funcParam && haspointers(src.Type)

Change-Id: I13c23fced52e8fcd0ae1df81b374df8632eb7790
Reviewed-on: https://go-review.googlesource.com/8932
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Dmitry Vyukov <dvyukov@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-04-14 15:45:26 +00:00
David Crawshaw
3b22ffc07e runtime: make cgocallback wait on package init
With the new buildmodes c-archive and c-shared, it is possible for a
cgo call to come in early in the lifecycle of a Go program. Calls
before the runtime has been initialized are caught by
_cgo_wait_runtime_init_done. However a call can come in after the
runtime has initialized, but before the program's package init
functions have finished running.

To avoid this cgocallback checks m.ncgo to see if we are on a thread
running Go. If not, we may be a foreign thread and it blocks until
main_init is complete.

Change-Id: I7a9f137fa2a40c322a0b93764261f9aa17fcf5b8
Reviewed-on: https://go-review.googlesource.com/8897
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
2015-04-14 13:39:02 +00:00
David Crawshaw
cea272de30 runtime: rename close to closefd
Avoids shadowing the builtin channel close function.

Change-Id: I7a729b0937c8248fe27222be61318a88db995eee
Reviewed-on: https://go-review.googlesource.com/8898
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
2015-04-14 12:31:29 +00:00
Nigel Tao
2f98bac310 image/jpeg: don't assume that an ensureNBits failure implies that we can
call unreadByteStuffedByte.

If ensureNBits was due to an io.EOF that was translated to
jpeg.errShortHuffmanData, then we may have read no bytes, so there is no
byte-stuffed-byte to unread.

Fixes #10387

Change-Id: I39a3842590c6cef2aa48943288d52f603338b44d
Reviewed-on: https://go-review.googlesource.com/8841
Reviewed-by: Rob Pike <r@golang.org>
2015-04-14 07:22:44 +00:00
Brad Fitzpatrick
8b27d28ed4 cmd/5g, etc: remove outdated float type alias comment
Change-Id: Ie5fe5cf3e2926ba4f91271bd47f3f998c26e003e
Reviewed-on: https://go-review.googlesource.com/8914
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
2015-04-14 04:41:20 +00:00
Brad Fitzpatrick
47f095501e net: remove old comment
The memory model has been clarified since. This is legal and doesn't
need justification.

Change-Id: I60f9938503f86f52bb568ca1a99ac721ee72cee5
Reviewed-on: https://go-review.googlesource.com/8913
Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>
2015-04-14 04:38:20 +00:00
Shenghou Ma
ce43e1fec8 cmd/dist: detect sse2 even with gccgo
Change-Id: Idfb20bfe130d9a54d9f5aae8eab8a34655d30610
Reviewed-on: https://go-review.googlesource.com/8865
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-04-13 23:27:35 +00:00
Srdjan Petrovic
41e9f8c4ed cmd: -buildmode=c-shared for linux/arm
Already supported platforms are linux/amd64 and android/arm.

Running -buildmode=c-shared on linux/arm is equivalent to:
  -ldflags "-shared" -asmflags "-shared"

Change-Id: Ifdb267f1d6508157f236be912fa369440172d161
Reviewed-on: https://go-review.googlesource.com/8895
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2015-04-13 23:25:12 +00:00
Ian Lance Taylor
607d5158c1 test: add gcc65755.go for http://gcc.gnu.org/PR65755
Change-Id: Ic35dff4c9a7fc6716ef9d5553a7b1769bed9be01
Reviewed-on: https://go-review.googlesource.com/8892
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 23:24:30 +00:00
Mikio Hara
3cbe7ea7e9 os: fix TestProgWideChdir on darwin
On darwin, /tmp and /var directories are usually linked to /private.

% cd $TMPDIR; pwd -L
/var/.../T
% pwd -P
/private/var/.../T

Change-Id: I277ff2d096344d9a80e6004a83e9fc3e1716348c
Reviewed-on: https://go-review.googlesource.com/8842
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2015-04-13 22:26:15 +00:00
Srdjan Petrovic
d1eee2cebf runtime: shared library init support for android/arm.
Follows http://golang.org/cl/8454, a similar CL for arm architectures.
This CL involves android-specific changes, namely, synthesizing
argv/auxv, as android doesn't provide those to the init functions.

This code is based on crawshaw@ android code in golang.org/x/mobile.

Change-Id: I32364efbb2662e80270a99bd7dfb1d0421b5417d
Reviewed-on: https://go-review.googlesource.com/8457
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2015-04-13 21:53:15 +00:00
Rob Pike
0d1c027bf3 doc/go1.5.txt: fmt fix for empty byte slice
Change-Id: I392cedc49847c8ea0daa38024fca97a289d805af
Reviewed-on: https://go-review.googlesource.com/8890
Reviewed-by: Rob Pike <r@golang.org>
2015-04-13 21:40:24 +00:00
Rob Pike
57058327c8 fmt: empty byte slices should print nothing in hex
The documentation is clear that formats like %02x applied to a
byte slice are per-element, so the result should be nothing if the
slice is empty. It's not, because the top-level padding routine is called.
It shouldn't be: the loop does the padding for us.

Fixes #10430.

Change-Id: I04ea0e804c0f2e70fff3701e5bf22acc90e890da
Reviewed-on: https://go-review.googlesource.com/8864
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-04-13 20:50:13 +00:00
Ian Lance Taylor
63cced7b31 net: document that DNSError.Timeout and Temporary are unreliable
Update #10417.

Change-Id: Ibfbdd05358f696a37217eef160f71b14a468ff86
Reviewed-on: https://go-review.googlesource.com/8788
Reviewed-by: Rob Pike <r@golang.org>
2015-04-13 20:41:50 +00:00
Dave Cheney
67805eaa95 cmd/dist: use gccgo as bootstrap compiler
Fixes #10092

This change makes it possible to use gccgo 5 as the GOROOT_BOOTSTRAP
compiler.

Change-Id: Ie3a312781ac1a09ea77f95b5a78c9488d437e0aa
Reviewed-on: https://go-review.googlesource.com/8809
Run-TryBot: Dave Cheney <dave@cheney.net>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-04-13 19:10:16 +00:00
David Crawshaw
8543cc5635 misc/cgo/testcarchive: avoid bad pointer passing
Change-Id: Ifbcc0eb24834f2f7d3b160d1dc911209723d9797
Reviewed-on: https://go-review.googlesource.com/8863
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-04-13 19:00:52 +00:00
David Crawshaw
4345a9fc5d misc/ios: support go run in go_darwin_arm_exec
The -lldb flag makes it easy to use go run and end up in a debugging
session on darwin/arm.

Change-Id: I556f93e950086a7dff4839f301b9c55f7579f87b
Reviewed-on: https://go-review.googlesource.com/8024
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
2015-04-13 18:59:52 +00:00
Srdjan Petrovic
93644c9118 runtime: shared library runtime init for arm
Adds the runtime initialization flow for arm akin to amd64.
In particular,we use the library initialization entry point to:
    - create a new OS thread and run the "regular" runtime init stack on
      that thread
    - return immediately from the main (i.e., loader) thread
    - at the first CGO invocation, we wait for the runtime initialization
      to complete.

Verified to work on a Raspberry Pi and an Android phone.

Change-Id: I32f39228ae30a03ce9569287f234b305790fecf6
Reviewed-on: https://go-review.googlesource.com/8455
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Srdjan Petrovic <spetrovic@google.com>
2015-04-13 18:58:18 +00:00
David Crawshaw
fdab2f92ea misc/cgo/testcarchive: test -buildmode=c-archive
Change-Id: I1668a6885c45180ff88fe673d04cec7eba395ee7
Reviewed-on: https://go-review.googlesource.com/8861
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-04-13 18:31:07 +00:00
Srdjan Petrovic
a888fcf7a7 runtime: remove runtime wait/notify from ppc64x architectures.
Related to issue #10410

For some reason, any non-trivial code in _cgo_wait_runtime_init_done
(even fprintf()) will crash that call.

If anybody has any guess why this is happening, please let me know!

For now, I'm clearing the functions for ppc64, as it's currently not used.

Change-Id: I1b11383aaf4f9f9a16f1fd6606842cfeedc9f0b3
Reviewed-on: https://go-review.googlesource.com/8766
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: Srdjan Petrovic <spetrovic@google.com>
2015-04-13 17:21:04 +00:00
Josh Bleecher Snyder
4af5dcb2db iostest.bash: do not restart device by default
This is friendlier for manual runs and personal devices.
Builders will pass -restart.

Fixes #10333.

Change-Id: Ia64c8f1660e275b5a1543d7f81f5f5efb623182f
Reviewed-on: https://go-review.googlesource.com/8870
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2015-04-13 16:42:11 +00:00
David Crawshaw
9725f2258b cmd/go: -buildmode=c-archive support
Change-Id: I469254384b0f4e5b5f08a18658934e19259935f9
Reviewed-on: https://go-review.googlesource.com/8718
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-04-13 13:21:20 +00:00
David Crawshaw
989f0ee80a runtime/cgo: EXC_BAD_ACCESS handler for arm64
Change-Id: Ia9ff9c0d381fad43fc5d3e5972dd6e66503733a5
Reviewed-on: https://go-review.googlesource.com/8815
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 12:08:37 +00:00
David Crawshaw
4c1ee3ea88 cmd/objdump: skip fork test on darwin/arm64
Just like darwin/arm.

Change-Id: Ibaba67980db6e05aa71568199b2dac2fcaa86fd6
Reviewed-on: https://go-review.googlesource.com/8824
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 12:03:36 +00:00
David Crawshaw
d5bb4380c8 cmd/pack: skip fork test on darwin/arm64
Just like darwin/arm.

Change-Id: I5ed26975670d4189a46b585a56c66c199905d168
Reviewed-on: https://go-review.googlesource.com/8823
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 11:58:27 +00:00
David Crawshaw
0a81d31b66 runtime/pprof: skip fork test on darwin/arm64
Just like darwin/arm.

Change-Id: Ic75927bd6457d37cda7dd8279fd9b4cd52edc1d1
Reviewed-on: https://go-review.googlesource.com/8813
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 11:58:03 +00:00
David Crawshaw
2ce82c6c65 cmd/go: run darwin/arm64 tests sequentially
Just like darwin/arm, the test devices can only install and execute
a single app at a time.

Change-Id: I74e6130ef83537c465b4585a366d02953fd907bf
Reviewed-on: https://go-review.googlesource.com/8827
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 11:57:34 +00:00
David Crawshaw
7db8835a50 runtime/debug: disable arm64 test for issue 9993
Like other arm64 platforms, darwin/arm64 has a different physical
page size to logical page size so it is running into issue 9993. I
hope it can be fixed for Go 1.5, but for now it is demonstrating the
same bug as the other skipped os+arch combinations.

Change-Id: Iedaf9afe56d6954bb4391b6e843d81742a75a00c
Reviewed-on: https://go-review.googlesource.com/8814
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 11:57:12 +00:00
David Crawshaw
439318dd50 crypto/x509: skip arm64 tests limited by iOS
Just like darwin/arm.

Change-Id: Ib0438021bfe9eb105222b93e5bb375c282cc7b8c
Reviewed-on: https://go-review.googlesource.com/8822
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 11:55:32 +00:00
David Crawshaw
b214a88d76 log/syslog: limiting tests on darwin/arm64
Just like darwin/arm.

Change-Id: Ic5c6c0b2fdbb89f4579677e120a8f2dbf300e5b9
Reviewed-on: https://go-review.googlesource.com/8820
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 11:54:28 +00:00
David Crawshaw
1d57943987 go/build: skip darwin/arm64 tests that need GOROOT
Just like darwin/arm.

Change-Id: I1a9f51c572c14b78d35ea62f52927f2bdc46e4c0
Reviewed-on: https://go-review.googlesource.com/8821
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 11:53:49 +00:00
David Crawshaw
5ad83082c0 os/exec: skip fork test on darwin/arm64
Just like darwin/arm.

Change-Id: Ia8c912e91259a5073aa3ab2b6509a18aa9a1fce7
Reviewed-on: https://go-review.googlesource.com/8818
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 11:53:09 +00:00
David Crawshaw
8c5f66bce4 path/filepath: skip test on darwin/arm64
Just like darwin/arm.

Change-Id: I4b0ab4a104f2c8a821ca8b5fa8d266e51883709f
Reviewed-on: https://go-review.googlesource.com/8816
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 11:52:46 +00:00
David Crawshaw
d6d423b99b runtime: skip fork test on darwin/arm64
Just like darwin/arm.

Change-Id: Ie4998d24b2d891a9f6c8047ec40cd3fdf80622cd
Reviewed-on: https://go-review.googlesource.com/8812
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 11:52:05 +00:00
David Crawshaw
c0d48836ec net/http/cgi: skip fork test on darwin/arm64
Just like darwin/arm.

Change-Id: Ib9a32bb0aed5f08b27de11a93aaf273cacdf5779
Reviewed-on: https://go-review.googlesource.com/8819
Reviewed-by: Minux Ma <minux@golang.org>
2015-04-13 11:51:53 +00:00
Brad Fitzpatrick
dc2d64bf81 cmd/go: cache results of HTTP requests done during meta tag discovery
Previously, running

  $ go get -u -v golang.org/x/tools/cmd/godoc

would results in dozens of HTTP requests for

  https://golang.org/x/tools?go-get=1

once per package under x/tools.

Now it caches the results. We still end up doing one HTTP request for
all the packages under x/tools, but this reduces the total number of
HTTP requests in ~half.

This also moves the singleflight package back into an internal
package. singleflight was originally elsewhere as a package, then got
copied into "net" (without its tests). But now that we have internal,
put it in its own package, and restore its test.

Fixes #9249

Change-Id: Ieb5cf04fc4d0a0c188cb957efdc7ea3068c34e3f
Reviewed-on: https://go-review.googlesource.com/8727
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
2015-04-13 07:08:00 +00:00
Alex Brainman
d1af6bed84 runtime: move all exception related code into signal_windows.go
Change-Id: I9654a5c85bd9b3ae9c7a9eddaef1ec752f42bd1b
Reviewed-on: https://go-review.googlesource.com/8840
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-04-13 07:04:21 +00:00
Colin Kennedy
e6092d64a7 image/gif: expose disposal, bg index and Config
The background index in the global palette (located in the image.Config)
is necessary for interpreting GIF frames properly

Frame disposal information is necessary for interpreting GIF frames in
the context of a sequence (or animation)

Removes decoder.flags as it can be a local variable

Change-Id: I6790a7febf6ba0859175c834c807bc6413e6b194
Reviewed-on: https://go-review.googlesource.com/4620
Reviewed-by: Nigel Tao <nigeltao@golang.org>
2015-04-13 04:35:04 +00:00
Matt T. Proud
926616da3f expvar: swap Float sync. from mutex to atomic.
Float type from a mutex to atomic bit array in a manner akin to
Google Guava's AtomicDouble[0], including adding a benchmark for the
type (benchcmp included below) along with some expvar_test.go cruft
being fixed.

benchmark             old ns/op     new ns/op     delta
BenchmarkFloatSet     115           9.37          -91.85%
BenchmarkFloatAdd     114           17.1          -85.00%

benchmark             old allocs     new allocs     delta
BenchmarkFloatSet     0              0              +0.00%
BenchmarkFloatAdd     0              0              +0.00%

benchmark             old bytes     new bytes     delta
BenchmarkFloatSet     0             0             +0.00%
BenchmarkFloatAdd     0             0             +0.00%

[0] - http://goo.gl/m4dtlI

Change-Id: I4ce6a913734ec692e3ed243f6e6f7c11da4c6036
Reviewed-on: https://go-review.googlesource.com/3687
Reviewed-by: Rob Pike <r@golang.org>
2015-04-12 23:07:50 +00:00
David du Colombier
ae740a459e os: add TestProgWideChdir
This test checks the working directory is
always consistent after Chdir in a Go program.

Fixes #10035.

Change-Id: I6abf0e4fcd40680ee572c6b40fc52ab17ef38d54
Reviewed-on: https://go-review.googlesource.com/6382
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: David du Colombier <0intro@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2015-04-12 19:03:13 +00:00
David du Colombier
7d3f81a9f3 syscall: ignore getwd errors when fixing working directory on Plan 9
In Plan 9, goroutines can run in different processes,
which don't share their working directory. However,
Go expects the working directory to be program-wide.

We use a Fixwd function to fix the working directory
before calling system calls which depend on the
working directory.

In fixwdLocked, the working directory is not fixed
when getwd returns an error. However, an error can
happen is some cases, notably when the directory
has been previously removed in another process.

Fixes #10422.

Change-Id: Ie0c36f97c4b5ebe27ff0ead360987c5b35f825e4
Reviewed-on: https://go-review.googlesource.com/8800
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2015-04-12 17:37:30 +00:00
Hyang-Ah (Hana) Kim
63c16b1878 cmd/go: fix a typo.
Change-Id: Ic453da17817f66e1073f6ba740b830b8daf2fc38
Reviewed-on: https://go-review.googlesource.com/8829
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2015-04-12 16:36:15 +00:00
Austin Clements
947b6a7ec8 debug/dwarf: add Entry.AttrField method to get *Field by Attr
Currently, Entry has a Val method that looks up an attribute and
returns its value. Now that Field has more fields than the attribute
and its value, it's useful to return the whole Field and let the
caller retrieve the parts it needs.

This change adds an AttrField method to Entry that does the same
lookup at Val, but returns the whole *Field rather than just the
value.

Change-Id: Ic629744c14c0e09d7528fa1026b0e1857789948c
Reviewed-on: https://go-review.googlesource.com/8503
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-04-12 14:38:00 +00:00
Austin Clements
d7d1337368 debug/dwarf: add DWARF attribute value class to Field
To return DWARF attribute values, debug/dwarf maps the DWARF attribute
value classes to Go types. Unfortunately, this mapping is ambiguous in
a way that makes it impossible to correctly interpret some DWARF
attributes as of DWARF 4. For example, AttrStartScope can be either a
constant or a rangelistptr. The attribute is interpreted differently
depending on its class, but debug/dwarf maps both classes to int64, so
the caller can't distinguish them from the Go type.
AttrDataMemberLocation is similar.

To address this, this change adds a field to type Field that indicates
the exact DWARF attribute value class of that field's value. This
makes it possible to distinguish value classes that can't be
distinguished by their Go type alone.

The root of this type ambiguity was DWARF itself. For example, DWARF 2
made no distinction between constants that were just constants and
constants that were section offsets because no attribute could have
both meanings. Hence, the single int64 type was sufficient. To avoid
introducing just another layer of ambiguity, this change takes pains
to canonicalize ambiguous classes in DWARF 2 and 3 files into the
unambiguous classes of DWARF 4.

Of course, there's no guarantee that future DWARF versions won't do
the same thing again and further subdivide the DWARF 4 classes. This
change gets ahead of this somewhat by distinguishing the various *ptr
classes even though the encoding does not. If there's some other form
of split, we can handle this in a backwards-compatible way by
introducing, for example, a Class5 field and type.

Change-Id: I4ef96d1223b0fd7f96ecf44fcc0e704a36af02b4
Reviewed-on: https://go-review.googlesource.com/8502
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-04-12 14:37:35 +00:00
David Crawshaw
ced7ffe95b cmd/interal/ld: darwin c-archive buildmode support
Uses ar to create an archive when -buildmode=c-archive.

A small example (that I hope to turn into a test in a later CL):

goarchive.go:
	package main

	import "fmt"

	import "C"

	func init() {
		fmt.Println("ran go init")
	}

	//export FuncInGo
	func FuncInGo() {
		fmt.Println("called a go function")
	}

	func main() {
		fmt.Println("in main")
	}

This can be compiled with:

	go build -ldflags=-buildmode=c-archive -o=libgo.a goarchive.go

main.c:

	#include <stdio.h>

	extern void FuncInGo();

	int main(void) {
		printf("c hello\n");
		FuncInGo();
		printf("c goodbye\n");
		return 0;
	}

Can be compiled with:

	cc main.c libgo.a

Apple provide a warning about the lack of PIE, but still produce a
binary which runs and outputs (on darwin/amd64):

	c hello
	ran go init
	called a go function
	c goodbye

Change-Id: I7611925f210a83afa6bd1e66a5601dd636a428c8
Reviewed-on: https://go-review.googlesource.com/8711
Reviewed-by: Ian Lance Taylor <iant@golang.org>
2015-04-12 14:00:32 +00:00