cmd/compile: include linknames in export data

This lets the compiler inline functions that contain a linknamed symbol.
Previously, the net/http tests would fail to build with -l=4 because
the compiler inlined functions that call net.byteIndex (which is
linknamed to strings.IndexByte).

This changes only the compiler-specific export data, so we don't need to
bump the export format version number.

The following benchmark results show how the size of package export data
is impacted by this change. These benchmarks were created by compiling
the go1 benchmark and running `go tool pack x` to extract the export
data from the resulting .a files.

name                                          old bytes   new bytes   delta
bufio                                        3.48k ± 0%  3.58k ± 0%  +2.90%
bytes                                        5.05k ± 0%  5.16k ± 0%  +2.16%
compress/bzip2                               2.61k ± 0%  2.68k ± 0%  +2.68%
compress/flate                               5.07k ± 0%  5.14k ± 0%  +1.40%
compress/gzip                                8.26k ± 0%  8.40k ± 0%  +1.70%
container/list                               1.69k ± 0%  1.76k ± 0%  +4.07%
context                                      3.93k ± 0%  4.01k ± 0%  +1.86%
crypto                                       1.03k ± 0%  1.03k ± 0%  +0.39%
crypto/aes                                     475 ± 0%    475 ± 0%  +0.00%
crypto/cipher                                1.18k ± 0%  1.18k ± 0%  +0.00%
crypto/des                                     502 ± 0%    502 ± 0%  +0.00%
crypto/dsa                                   5.71k ± 0%  5.77k ± 0%  +1.16%
crypto/ecdsa                                 6.67k ± 0%  6.75k ± 0%  +1.08%
crypto/elliptic                              6.28k ± 0%  6.35k ± 0%  +1.07%
crypto/hmac                                    464 ± 0%    464 ± 0%  +0.00%
crypto/internal/cipherhw                       313 ± 0%    313 ± 0%  +0.00%
crypto/md5                                     691 ± 0%    695 ± 0%  +0.58%
crypto/rand                                  5.37k ± 0%  5.43k ± 0%  +1.23%
crypto/rc4                                     512 ± 0%    512 ± 0%  +0.00%
crypto/rsa                                   7.05k ± 0%  7.12k ± 0%  +1.05%
crypto/sha1                                    756 ± 0%    760 ± 0%  +0.53%
crypto/sha256                                  523 ± 0%    523 ± 0%  +0.00%
crypto/sha512                                  662 ± 0%    662 ± 0%  +0.00%
crypto/subtle                                  835 ± 0%    873 ± 0%  +4.55%
crypto/tls                                   28.1k ± 0%  28.5k ± 0%  +1.30%
crypto/x509                                  17.7k ± 0%  17.9k ± 0%  +1.04%
crypto/x509/pkix                             9.75k ± 0%  9.90k ± 0%  +1.50%
encoding                                       473 ± 0%    473 ± 0%  +0.00%
encoding/asn1                                1.41k ± 0%  1.42k ± 0%  +1.00%
encoding/base64                              1.67k ± 0%  1.69k ± 0%  +0.90%
encoding/binary                              2.65k ± 0%  2.76k ± 0%  +4.07%
encoding/gob                                 13.3k ± 0%  13.5k ± 0%  +1.65%
encoding/hex                                   854 ± 0%    857 ± 0%  +0.35%
encoding/json                                11.9k ± 0%  12.1k ± 0%  +1.71%
encoding/pem                                   484 ± 0%    484 ± 0%  +0.00%
errors                                         360 ± 0%    361 ± 0%  +0.28%
flag                                         7.32k ± 0%  7.42k ± 0%  +1.48%
fmt                                          1.42k ± 0%  1.42k ± 0%  +0.00%
go/ast                                       15.7k ± 0%  15.8k ± 0%  +1.07%
go/parser                                    7.48k ± 0%  7.59k ± 0%  +1.55%
go/scanner                                   3.88k ± 0%  3.94k ± 0%  +1.39%
go/token                                     3.51k ± 0%  3.53k ± 0%  +0.60%
hash                                           507 ± 0%    507 ± 0%  +0.00%
hash/crc32                                     685 ± 0%    685 ± 0%  +0.00%
internal/nettrace                              474 ± 0%    474 ± 0%  +0.00%
internal/pprof/profile                       8.29k ± 0%  8.36k ± 0%  +0.89%
internal/race                                  511 ± 0%    511 ± 0%  +0.00%
internal/singleflight                          966 ± 0%    969 ± 0%  +0.31%
internal/syscall/unix                          427 ± 0%    427 ± 0%  +0.00%
io                                           3.48k ± 0%  3.52k ± 0%  +1.15%
io/ioutil                                    5.30k ± 0%  5.38k ± 0%  +1.53%
log                                          4.46k ± 0%  4.53k ± 0%  +1.59%
math                                         3.72k ± 0%  3.75k ± 0%  +0.75%
math/big                                     8.91k ± 0%  9.01k ± 0%  +1.15%
math/rand                                    1.29k ± 0%  1.30k ± 0%  +0.46%
mime                                         2.59k ± 0%  2.63k ± 0%  +1.55%
mime/multipart                               3.61k ± 0%  3.68k ± 0%  +1.80%
mime/quotedprintable                         2.20k ± 0%  2.25k ± 0%  +2.50%
net                                          21.1k ± 0%  21.3k ± 0%  +1.10%
net/http                                     56.6k ± 0%  57.3k ± 0%  +1.28%
net/http/httptest                            33.6k ± 0%  34.1k ± 0%  +1.38%
net/http/httptrace                           14.4k ± 0%  14.5k ± 0%  +1.29%
net/http/internal                            2.70k ± 0%  2.77k ± 0%  +2.59%
net/textproto                                4.51k ± 0%  4.60k ± 0%  +1.82%
net/url                                      1.71k ± 0%  1.73k ± 0%  +1.41%
os                                           11.3k ± 0%  11.4k ± 0%  +1.36%
path                                           587 ± 0%    589 ± 0%  +0.34%
path/filepath                                4.46k ± 0%  4.55k ± 0%  +1.88%
reflect                                      6.39k ± 0%  6.43k ± 0%  +0.72%
regexp                                       5.82k ± 0%  5.88k ± 0%  +1.12%
regexp/syntax                                3.22k ± 0%  3.24k ± 0%  +0.62%
runtime                                      12.9k ± 0%  13.2k ± 0%  +1.94%
runtime/cgo                                    229 ± 0%    229 ± 0%  +0.00%
runtime/debug                                3.66k ± 0%  3.72k ± 0%  +1.86%
runtime/internal/atomic                        905 ± 0%    905 ± 0%  +0.00%
runtime/internal/sys                         2.00k ± 0%  2.05k ± 0%  +2.55%
runtime/pprof                                4.16k ± 0%  4.23k ± 0%  +1.66%
runtime/pprof/internal/protopprof            11.5k ± 0%  11.7k ± 0%  +1.27%
runtime/trace                                  354 ± 0%    354 ± 0%  +0.00%
sort                                         1.63k ± 0%  1.68k ± 0%  +2.94%
strconv                                      1.84k ± 0%  1.85k ± 0%  +0.54%
strings                                      3.87k ± 0%  3.97k ± 0%  +2.48%
sync                                         1.51k ± 0%  1.52k ± 0%  +0.33%
sync/atomic                                  1.58k ± 0%  1.60k ± 0%  +1.27%
syscall                                      53.2k ± 0%  53.3k ± 0%  +0.20%
testing                                      8.14k ± 0%  8.26k ± 0%  +1.49%
testing/internal/testdeps                      597 ± 0%    598 ± 0%  +0.17%
text/tabwriter                               3.09k ± 0%  3.14k ± 0%  +1.85%
text/template                                15.4k ± 0%  15.7k ± 0%  +1.89%
text/template/parse                          8.90k ± 0%  9.12k ± 0%  +2.46%
time                                         5.75k ± 0%  5.86k ± 0%  +1.86%
unicode                                      4.62k ± 0%  4.62k ± 0%  +0.07%
unicode/utf16                                  693 ± 0%    706 ± 0%  +1.88%
unicode/utf8                                 1.05k ± 0%  1.07k ± 0%  +1.14%
vendor/golang_org/x/crypto/chacha20poly1305  1.25k ± 0%  1.26k ± 0%  +0.64%
vendor/golang_org/x/crypto/curve25519          392 ± 0%    392 ± 0%  +0.00%
vendor/golang_org/x/crypto/poly1305            426 ± 0%    426 ± 0%  +0.00%
vendor/golang_org/x/net/http2/hpack          4.19k ± 0%  4.26k ± 0%  +1.69%
vendor/golang_org/x/net/idna                   355 ± 0%    355 ± 0%  +0.00%
vendor/golang_org/x/net/lex/httplex            609 ± 0%    615 ± 0%  +0.99%
vendor/golang_org/x/text/transform           1.31k ± 0%  1.31k ± 0%  +0.08%
vendor/golang_org/x/text/unicode/norm        5.78k ± 0%  5.90k ± 0%  +2.06%
vendor/golang_org/x/text/width               1.24k ± 0%  1.24k ± 0%  +0.16%
[Geo mean]                                    2.49k       2.52k       +1.10%

Fixes #18167.

Change-Id: Ia5b7e70adc9652c7ee9954ca2efc1c59fa79be2b
Reviewed-on: https://go-review.googlesource.com/33911
Run-TryBot: David Lazar <lazard@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Reviewed-by: David Chase <drchase@google.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/test/linkname.go b/test/linkname.go
new file mode 100644
index 0000000000..c94a113c90
--- /dev/null
+++ b/test/linkname.go
@@ -0,0 +1,15 @@
+// errorcheckandrundir -0 -m -l=4
+
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Tests that linknames are included in export data (issue 18167).
+package ignored
+
+/*
+Without CL 33911, this test would fail with the following error:
+
+main.main: relocation target linkname2.byteIndex not defined
+main.main: undefined: "linkname2.byteIndex"
+*/