- position info for all exported globals, plus methods and fields
- use delta-encoded line number info in most cases
- canonicalize all strings: each filename appears only once,
  but will also compact other strings (names) to at most one
  occurence in encoding
- positions not yet hooked up when reading in

Also:
- adjusted go/importer (gcimporter)
- some refactoring for better symmetry

Stats:
- comparison of export data size w/o and w/ position info (bytes).
- delta is increase in %
- overall (see bottom of table): 14% increase
- however, the current binary format decreased from
  the original binary format last week by 14%
- compared to original textual format: 65% decrease
  (increase by 14% after decrease by 14% still leads
  to a decrease from original textual format)

(caveat: we used the textual size from last week, assuming
it has not changed - there may be a small error here).

package				w/o pos	w/ pos	delta

archive/tar			4234	4902	16%
archive/zip			6387	7340	15%
bufio				3106	3419	10%
bytes				4362	4757	9%
cmd/addr2line			27	70	159%
cmd/api				12065	13590	13%
cmd/asm				27	64	137%
cmd/asm/internal/arch		9957	11529	16%
cmd/asm/internal/asm		11788	13385	14%
cmd/asm/internal/flags		239	311	30%
cmd/asm/internal/lex		13415	15358	14%
cmd/cgo				13064	15006	15%
cmd/compile			27	67	148%
cmd/compile/internal/amd64	461	869	89%
cmd/compile/internal/arm	5963	7273	22%
cmd/compile/internal/arm64	363	657	81%
cmd/compile/internal/big	7186	8590	20%
cmd/compile/internal/gc		48242	56234	17%
cmd/compile/internal/mips64	367	666	81%
cmd/compile/internal/ppc64	372	721	94%
cmd/compile/internal/s390x	330	569	72%
cmd/compile/internal/ssa	30464	35058	15%
cmd/compile/internal/x86	429	770	79%
cmd/cover			3984	4731	19%
cmd/dist			74	154	108%
cmd/doc				7272	8591	18%
cmd/expdump			27	71	163%
cmd/fix				342	419	23%
cmd/go				8126	9520	17%
cmd/gofmt			27	70	159%
cmd/gofmt2			27	69	156%
cmd/gofmt2/internal/format	702	856	22%
cmd/gofmt2/internal/lexical	2954	3509	19%
cmd/gofmt2/internal/parse	6185	7295	18%
cmd/gofmt2/internal/syntax	3533	4738	34%
cmd/gofmt2/internal/test	540	615	14%
cmd/internal/bio		5395	6060	12%
cmd/internal/gcprog		533	663	24%
cmd/internal/goobj		1022	1277	25%
cmd/internal/obj		10951	12825	17%
cmd/internal/obj/arm		8612	9985	16%
cmd/internal/obj/arm64		15814	17638	12%
cmd/internal/obj/mips		10928	12487	14%
cmd/internal/obj/ppc64		13576	15277	13%
cmd/internal/obj/s390x		16513	18708	13%
cmd/internal/obj/x86		21152	23482	11%
cmd/internal/objfile		14442	16505	14%
cmd/internal/pprof/commands	1663	1885	13%
cmd/internal/pprof/driver	9517	10789	13%
cmd/internal/pprof/fetch	7632	8635	13%
cmd/internal/pprof/plugin	13150	14809	13%
cmd/internal/pprof/profile	7004	8248	18%
cmd/internal/pprof/report	7763	8942	15%
cmd/internal/pprof/svg		1332	1534	15%
cmd/internal/pprof/symbolizer	7376	8439	14%
cmd/internal/pprof/symbolz	6970	7976	14%
cmd/internal/pprof/tempfile	3645	4093	12%
cmd/internal/sys		505	619	23%
cmd/internal/unvendor/golang.org/x/arch/arm/armasm	73951	79188	7%
cmd/internal/unvendor/golang.org/x/arch/x86/x86asm	10140	11738	16%
cmd/link			27	64	137%
cmd/link/internal/amd64		9317	11034	18%
cmd/link/internal/arm		110	213	94%
cmd/link/internal/arm64		112	219	96%
cmd/link/internal/ld		53524	60149	12%
cmd/link/internal/mips64	113	222	96%
cmd/link/internal/ppc64		113	220	95%
cmd/link/internal/s390x		112	219	96%
cmd/link/internal/x86		110	212	93%
cmd/nm				27	61	126%
cmd/objdump			27	68	152%
cmd/pack			4141	4688	13%
cmd/pprof			27	67	148%
cmd/trace			624	842	35%
cmd/vet				11194	13140	17%
cmd/vet/internal/whitelist	52	113	117%
cmd/yacc			1141	1317	15%
compress/bzip2			2101	2484	18%
compress/flate			3619	4336	20%
compress/gzip			6261	7111	14%
compress/lzw			276	401	45%
compress/zlib			3630	4158	15%
container/heap			187	250	34%
container/list			1370	1506	10%
container/ring			466	546	17%
context				3005	3338	11%
crypto				728	856	18%
crypto/aes			181	321	77%
crypto/cipher			744	1163	56%
crypto/des			220	320	45%
crypto/dsa			4526	4990	10%
crypto/ecdsa			5341	5982	12%
crypto/elliptic			4969	5593	13%
crypto/hmac			188	250	33%
crypto/md5			560	706	26%
crypto/rand			4218	4746	13%
crypto/rc4			214	321	50%
crypto/rsa			5648	6355	13%
crypto/sha1			597	751	26%
crypto/sha256			228	351	54%
crypto/sha512			354	484	37%
crypto/subtle			586	621	6%
crypto/tls			20909	23438	12%
crypto/x509			14862	16857	13%
crypto/x509/pkix		8384	9278	11%
database/sql			6721	7715	15%
database/sql/driver		1243	1535	23%
debug/dwarf			7867	9153	16%
debug/elf			25479	28025	10%
debug/gosym			1887	2267	20%
debug/macho			7222	8846	22%
debug/pe			6921	8081	17%
debug/plan9obj			1084	1319	22%
encoding			217	280	29%
encoding/ascii85		587	722	23%
encoding/asn1			1043	1268	22%
encoding/base32			929	1112	20%
encoding/base64			1166	1368	17%
encoding/binary			2168	2410	11%
encoding/csv			3761	4203	12%
encoding/gob			11304	12936	14%
encoding/hex			510	606	19%
encoding/json			9965	11395	14%
encoding/pem			202	266	32%
encoding/xml			11817	13361	13%
errors				126	170	35%
expvar				930	1142	23%
flag				5905	6519	10%
fmt				1027	1190	16%
go/ast				12910	15541	20%
go/build			5460	6173	13%
go/constant			1645	1816	10%
go/doc				3107	3882	25%
go/format			1416	1729	22%
go/importer			1426	1668	17%
go/internal/gccgoimporter	1624	2028	25%
go/internal/gcimporter		2650	3095	17%
go/parser			6220	7073	14%
go/printer			1924	2306	20%
go/scanner			3137	3602	15%
go/token			3053	3474	14%
go/types			21793	25561	17%
hash				234	327	40%
hash/adler32			465	553	19%
hash/crc32			668	817	22%
hash/crc64			630	727	15%
hash/fnv			1413	1582	12%
html				76	114	50%
html/template			14382	16457	14%
image				10248	11409	11%
image/color			2247	2562	14%
image/color/palette		107	169	58%
image/draw			2313	2494	8%
image/gif			3079	3450	12%
image/internal/imageutil	3136	3456	10%
image/jpeg			2349	2735	16%
image/png			2404	2695	12%
index/suffixarray		4978	5596	12%
internal/race			225	278	24%
internal/singleflight		551	697	26%
internal/syscall/windows/sysdll	97	166	71%
internal/testenv		4488	5052	13%
internal/trace			1392	1680	21%
io				2811	3318	18%
io/ioutil			3988	4467	12%
log				3532	3907	11%
log/syslog			4247	4775	12%
math				3021	4499	49%
math/big			7250	8456	17%
math/cmplx			1034	1617	56%
math/rand			734	885	21%
mime				1889	2194	16%
mime/multipart			4313	4849	12%
mime/quotedprintable		1758	1996	14%
net				15686	18617	19%
net/http			42182	47848	13%
net/http/cgi			19496	21768	12%
net/http/cookiejar		4615	5248	14%
net/http/fcgi			17758	19771	11%
net/http/httptest		26108	29350	12%
net/http/httputil		20732	23286	12%
net/http/internal		2195	2497	14%
net/http/pprof			17596	19545	11%
net/internal/socktest		1689	2153	27%
net/mail			4328	4810	11%
net/rpc				24328	27249	12%
net/rpc/jsonrpc			11052	12438	13%
net/smtp			17127	19174	12%
net/textproto			3705	4329	17%
net/url				1193	1371	15%
os				8493	10113	19%
os/exec				6625	7532	14%
os/signal			137	236	72%
os/user				529	761	44%
path				295	372	26%
path/filepath			3452	3952	14%
reflect				5091	6028	18%
regexp				4848	5585	15%
regexp/syntax			2590	3076	19%
runtime				8721	11598	33%
runtime/cgo			17	17	0%
runtime/debug			2721	3130	15%
runtime/internal/atomic		569	704	24%
runtime/internal/sys		1874	2318	24%
runtime/pprof			478	582	22%
runtime/race			18	18	0%
runtime/trace			95	146	54%
sort				1052	1215	15%
strconv				1389	1667	20%
strings				3372	3772	12%
sync				946	1371	45%
sync/atomic			962	1079	12%
syscall				41574	45613	10%
testing				6184	7243	17%
testing/iotest			883	1116	26%
testing/quick			4659	5443	17%
text/scanner			2930	3269	12%
text/tabwriter			2333	2607	12%
text/template			13335	15274	15%
text/template/parse		8270	9285	12%
time				4687	5313	13%
unicode				3831	4355	14%
unicode/utf16			530	584	10%
unicode/utf8			872	946	8%
vendor/golang.org/x/net/http2/hpack	3386	3970	17%

				1295440	1481566	14%
orig. textual			4253585	1481566	-65%
orig. binary			1724071	1481566 -14%

Change-Id: I4177c6511cc57ebe5eb80c89bf3aefc83376ce86
Reviewed-on: https://go-review.googlesource.com/22096Reviewed-by: Matthew Dempsky <mdempsky@google.com>