We create appropriate ELF files automatically based on GOOS. There's
no point in supporting -H elf flag, particularly since we need to emit
different flavors of ELF depending on GOOS anyway.
If that weren't reason enough, -H elf appears to be broken since at
least Go 1.4. At least I wasn't able to find a way to make use of it.
As best I can tell digging through commit history, -H elf is just an
artifact leftover from Plan 9's 6l linker.
Change-Id: I7393caaadbc60107bbd6bc99b976a4f4fe6b5451
Reviewed-on: https://go-review.googlesource.com/21343
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This only tests amd64 because it's currently broken on non-SSA
backends.
Fixes#8613
Change-Id: I6bc501c81c395e533bb9c7335789750e0c6b7a8f
Reviewed-on: https://go-review.googlesource.com/21325
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The http2 spec defines a magic string which initates an http2 session:
"PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n"
It was intentionally chosen to kinda look like an HTTP request, but
just different enough to break things not ready for it. This change
makes Go ready for it.
Notably: Go now accepts the request header (the prefix "PRI *
HTTP/2.0\r\n\r\n") as a valid request, even though it doesn't have a
Host header. But we now mark it as "Connection: close" and teach the
Server to never read a second request from the connection once that's
seen. If the http.Handler wants to deal with the upgrade, it has to
hijack the request, read out the "body", compare it against
"SM\r\n\r\n", and then speak http2. One of the new tests demonstrates
that hijacking.
Fixes#14451
Updates #14141 (h2c)
Change-Id: Ib46142f31c55be7d00c56fa2624ec8a232e00c43
Reviewed-on: https://go-review.googlesource.com/21327
Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This makes sure the net/http package never attempts to transmit a
bogus header field key or value and instead fails fast with an error
to the user, rather than relying on the server to maybe return an
error.
It's still possible to use x/net/http2.Transport directly to send
bogus stuff. This change only stops h1 & h2 usage via the net/http
package. A future change will update x/net/http2.
This change also moves some code from request.go to lex.go, which in a
separate future change should be moved so it can be shared with http2
to reduce code bloat.
Updates #14048
Change-Id: I0a44ae1ab357fbfcbe037aa4b5d50669a87f2856
Reviewed-on: https://go-review.googlesource.com/21326
Reviewed-by: Andrew Gerrand <adg@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Test to follow in a separate CL that arranges for the runtime package to
store non-Go addresses in a CPU profile.
Change-Id: I33ce1d66b77340b1e62b54505fc9b1abcec108a9
Reviewed-on: https://go-review.googlesource.com/21055
Reviewed-by: Austin Clements <austin@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Only use REP;MOVSB if:
1) The CPUID flag says it is fast, and
2) The pointers are unaligned
Otherwise, use REP;MOVSQ.
Update #14630
Change-Id: I946b28b87880c08e5eed1ce2945016466c89db66
Reviewed-on: https://go-review.googlesource.com/21300
Reviewed-by: Nigel Tao <nigeltao@golang.org>
Fixes#14522.
As I said on that issue:
----
This is a progressive JPEG image. There are two dimensions of
progressivity: spectral selection (variables zs and ze in scan.go,
ranging in [0, 63]) and successive approximation (variables ah and al in
scan.go, ranging in [0, 8), from LSB to MSB, although ah=0 implicitly
means ah=8).
For this particular image, there are three components, and the SOS
markers contain this progression:
zs, ze, ah, al: 0 0 0 0 components: 0, 1, 2
zs, ze, ah, al: 1 63 0 0 components: 1
zs, ze, ah, al: 1 63 0 0 components: 2
zs, ze, ah, al: 1 63 0 2 components: 0
zs, ze, ah, al: 1 10 2 1 components: 0
zs, ze, ah, al: 11 63 2 1 components: 0
zs, ze, ah, al: 1 10 1 0 components: 0
The combination of all of these is complete (i.e. spectra 0 to 63 and
bits 8 exclusive to 0) for components 1 and 2, but it is incomplete for
component 0 (the luma component). In particular, there is no data for
component 0, spectra 11 to 63 and bits 1 exclusive to 0.
The image/jpeg code, as of Go 1.6, waits until both dimensions are
complete before performing the de-quantization, IDCT and copy to an
*image.YCbCr. This is the "if zigEnd != blockSize-1 || al != 0 { ...
continue }" code and associated commentary in scan.go.
Almost all progressive JPEG images end up complete in both dimensions
for all components, but this particular image is incomplete for
component 0, so the Go code never writes anything to the Y values of the
resultant *image.YCbCr, which is why the broken output is so dark (but
still looks recognizable in terms of red and blue hues).
My reading of the ITU T.81 JPEG specification (Annex G) doesn't
explicitly say that this is a valid image, but it also doesn't rule it
out.
In any case, the fix is, for progressive JPEG images, to always
reconstruct the decoded blocks (by performing the de-quantization, IDCT
and copy to an *image.YCbCr), regardless of whether or not they end up
complete. Note that, in Go, the jpeg.Decode function does not return
until the entire image is decoded, so we still only want to reconstruct
each block once, not once per SOS (Start Of Scan) marker.
----
A test image was also added, based on video-001.progressive.jpeg. When
decoding that image, inserting a
println("nComp, zs, ze, ah, al:", nComp, zigStart, zigEnd, ah, al)
into decoder.processSOS in scan.go prints:
nComp, zs, ze, ah, al: 3 0 0 0 1
nComp, zs, ze, ah, al: 1 1 5 0 2
nComp, zs, ze, ah, al: 1 1 63 0 1
nComp, zs, ze, ah, al: 1 1 63 0 1
nComp, zs, ze, ah, al: 1 6 63 0 2
nComp, zs, ze, ah, al: 1 1 63 2 1
nComp, zs, ze, ah, al: 3 0 0 1 0
nComp, zs, ze, ah, al: 1 1 63 1 0
nComp, zs, ze, ah, al: 1 1 63 1 0
nComp, zs, ze, ah, al: 1 1 63 1 0
In other words, video-001.progressive.jpeg contains 10 different scans.
This little program below drops half of them (remembering to keep the
"\xff\xd9" End of Image marker):
----
package main
import (
"bytes"
"io/ioutil"
"log"
)
func main() {
sos := []byte{0xff, 0xda}
eoi := []byte{0xff, 0xd9}
src, err := ioutil.ReadFile("video-001.progressive.jpeg")
if err != nil {
log.Fatal(err)
}
b := bytes.Split(src, sos)
println(len(b)) // Prints 11.
dst := bytes.Join(b[:5], sos)
dst = append(dst, eoi...)
if err := ioutil.WriteFile("video-001.progressive.truncated.jpeg", dst, 0666); err != nil {
log.Fatal(err)
}
}
----
The video-001.progressive.truncated.jpeg was converted to png via
libjpeg and ImageMagick:
djpeg -nosmooth video-001.progressive.truncated.jpeg > tmp.tga
convert tmp.tga video-001.progressive.truncated.png
rm tmp.tga
Change-Id: I72b20cd4fb6746d36d8d4d587f891fb3bc641f84
Reviewed-on: https://go-review.googlesource.com/21062
Reviewed-by: Rob Pike <r@golang.org>
In tostruct0 and tofunargs we take a list of nodes, transform them into
a slice of Fields, set the fields on a type, then use the IterFields
iterator to iterate over the list again to see if any of them are
broken.
As we know the slice of fielde-we just created it-we can combine these two
interations into one pass over the fields.
Change-Id: I8b04c90fb32fd6c3b1752cfc607128a634ee06c5
Reviewed-on: https://go-review.googlesource.com/21350
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
This allows us to get rid of Isptr and Issigned. Still some code to
clean up for Isint, Isfloat, and Iscomplex.
CL produced mechanically using gofmt -w -r.
Passes toolstash -cmp.
Change-Id: If4f807bb7f2b357288d2547be2380eb511875786
Reviewed-on: https://go-review.googlesource.com/21339
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
* This is an improved version of an earlier patch.
* Verified with gcc up to 100.
* Limited to two instructions based on costs from
https://gmplib.org/~tege/x86-timing.pdf
Change-Id: Ib7c37de6fd8e0ba554459b15c7409508cbcf6728
Reviewed-on: https://go-review.googlesource.com/21103
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Replace Isfixedarray, Isslice, and Isinter with the IsArray, IsSlice,
and IsInterface methods added for SSA. Rewrite performed mechanically
using gofmt -w -r "Isfoo(t) -> t.IsFoo()".
Because the IsFoo methods panic when given a nil pointer, a handful of
call sites had to be modified to check for nil Type values. These
aren't strictly necessary, because nil Type values should only occur
in invalid Go source programs, so it would be okay if we panicked on
them and gave up type checking the rest of the package. However, there
are a couple regress tests that expect we continue, so add checks to
keep those tests passing. (See #15029.)
Passes toolstash -cmp.
Change-Id: I511c6ac4cfdf3f9cbdb3e52a5fa91b6d09d82f80
Reviewed-on: https://go-review.googlesource.com/21336
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Apparently I’m having a hard time following my
own naming scheme.
Change-Id: I99c801bef09fa65c1f0e8ecc2fba154a495e9c17
Reviewed-on: https://go-review.googlesource.com/21332
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
This removes almost all direct access to
Type’s heavily overloaded Type field.
Mostly generated by eg, manually checked.
Significant manual changes:
* reflect.go's typPkg used Type indiscriminately.
Use it only for specific etypes.
* gen.go's visitComponents contained a usage of Type
with structs. Using Type for structs no longer
occurs, and the Fatal contained therein has not triggered,
so it has been axed.
* Scary code in cgen.go's cgen_slice is now explicitly scary.
Passes toolstash -cmp.
Change-Id: I2dbfb3c959da7ae239f964d83898c204affcabc6
Reviewed-on: https://go-review.googlesource.com/21331
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Also, add two uses of Key and Val that I missed earlier.
As before, direct writes to Down and Type remain in bimport.
Change-Id: I487aa975926b30092db1ad74ace17994697117c1
Reviewed-on: https://go-review.googlesource.com/21330
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Partial revert of https://golang.org/cl/20967 which
I can't reproduce and actually breaks me more.
Fixes#14901
Change-Id: I8cce443fbd95f5f6f2a5b6a4b9f2faab36167a12
Reviewed-on: https://go-review.googlesource.com/21292
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Previously, t.IsPtr() reported whether t was represented with a
pointer, but some of its callers expected it to report whether t is an
actual Go pointer. Resolve this by renaming t.IsPtr to t.IsPtrShaped
and adding a new t.IsPtr method to report Go pointer types.
Updated a couple callers in gc/ssa.go to use IsPtr instead of
IsPtrShaped.
Passes toolstash -cmp.
Updates #15028.
Change-Id: I0a8154b5822ad8a6ad296419126ad01a3d2a5dc5
Reviewed-on: https://go-review.googlesource.com/21232
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Changes generated by eg and manually checked.
Isfixedarray, Isslice, and many other
Type-related functions in subr.go should
either be deleted or moved to type.go.
Later, though; the game now is cleanup via encapsulation.
Passes toolstash -cmp.
Change-Id: I83dd8816f6263b74367d23c2719a08c362e330f9
Reviewed-on: https://go-review.googlesource.com/21303
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Happens occasionally for boolean phis was used as a control.
Change-Id: Ie0f2483e9004c1706751d8dfb25ee2e5106d917e
Reviewed-on: https://go-review.googlesource.com/21310
Run-TryBot: Alexandru Moșoi <alexandru@mosoi.ro>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
The Read logic should not assume that only (0, io.EOF) is returned
instead of (n, io.EOF) where n is positive.
The fix done here is very similar to the fix to compress/zlib
in CL/20292.
Change-Id: Icb76258cdcf8cfa386a60bab330fefde46fc071d
Reviewed-on: https://go-review.googlesource.com/21308
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
It is valid for io.Reader to return (n, io.EOF) where n is positive.
The unit test should not fail if io.EOF is returned when read until
the end.
Change-Id: I7b918e3cc03db8b90c8aa58f4c0f7806a1d4af7e
Reviewed-on: https://go-review.googlesource.com/21307
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
s390x doesn't introduce any new assembly syntax. There are a few
instructions which require the operands to be reordered, notably
the storage-storage instructions that put the length into From3 so
that the memory operands can be put into From and To.
The assembly test currently covers a subset of instructions but
tries to hit edge cases as much as possible. Unlike the other ports
it can be linked as an executable to make disassembling it easy.
It would be nice to autogenerate it at some point in the future.
Change-Id: I8dd542c34b9e450b8129d46693a5acb0ded791ce
Reviewed-on: https://go-review.googlesource.com/21253
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
substAny needs access to many internal details
of gc.Type. substArgTypes comes along for the ride.
Change-Id: I430a4edfd54a1266522f7a9818e5e7b5da72479c
Reviewed-on: https://go-review.googlesource.com/21250
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Based on the ppc64 port.
s390x supports 2, 4 and 6 byte instructions and Go assembly
instructions sometimes map to several s390x instructions. The
assembler loops until a fixed point is reached in order to use
branch instructions that can only handle a short offset in a
similar way to other ports.
Change-Id: I4278bf46aca35a96ca9cea0857e6229643c9c1e3
Reviewed-on: https://go-review.googlesource.com/20942
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Previously if we were only using the low bits of AuxInt,
the high bits were ignored and could be junk. This CL
changes that behavior to define the high bits to be the
sign-extended version of the low bits for all cases.
There are 2 main benefits:
- Deterministic representation. This helps with CSE.
(Const8 [0x1]) and (Const8 [0x101]) used to be the same "value"
but CSE couldn't see them as such.
- Testability. We can check that all ops leave AuxInt in a state
consistent with the new rule. In the old scheme, it was hard
to check whether a rule correctly used only the low-order bits.
Side benefits:
- ==0 and !=0 tests are easier.
Drawbacks:
- This differs from the runtime representation in registers,
where it is important that we allow upper bits to be undefined
(so we're not sign/zero-extending all the time).
- Ops that treat AuxInt as unsigned (shifts, mostly) need to be
a bit more careful.
Change-Id: I9a685ff27e36dc03287c9ab1cecd6c0b4045c819
Reviewed-on: https://go-review.googlesource.com/21256
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Flip around the composition order of the http.Response.Body's
gzip.Reader vs. the reader which keeps track of waiting to see the end
of the HTTP/1 response framing (whether that's a Content-Length or
HTTP/1.1 chunking).
Previously:
user -> http.Response.Body
-> bodyEOFSignal
-> gzipReader
-> gzip.Reader
-> bufio.Reader
[ -> http/1.1 de-chunking reader ] optional
-> http1 framing *body
But because bodyEOFSignal was waiting to see an EOF from the
underlying gzip.Reader before reusing the connection, and gzip.Reader
(or more specifically: the flate.Reader) wasn't returning an early
io.EOF with the final chunk, the bodyEOfSignal was never releasing the
connection, because the EOF from the http1 framing was read by a party
who didn't care about it yet: the helper bufio.Reader created to do
byte-at-a-time reading in the flate.Reader.
Flip the read composition around to:
user -> http.Response.Body
-> gzipReader
-> gzip.Reader
-> bufio.Reader
-> bodyEOFSignal
[ -> http/1.1 de-chunking reader ] optional
-> http1 framing *body
Now when gzip.Reader does its byte-at-a-time reading via the
bufio.Reader, the bufio.Reader will do its big reads against the
bodyEOFSignal reader instead, which will then see the underlying http1
framing EOF, and be able to reuse the connection.
Updates google/go-github#317
Updates #14867
And related abandoned fix to flate.Reader: https://golang.org/cl/21290
Change-Id: I3729dfdffe832ad943b84f4734b0f59b0e834749
Reviewed-on: https://go-review.googlesource.com/21291
Reviewed-by: David Symonds <dsymonds@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Record total number of relocations, pcdata, automatics, funcdata and files in
object file and use these numbers in the linker to allocate contiguous
slices to later be filled by the defined symbols.
name old secs new secs delta
LinkCmdGo 0.52 ± 3% 0.49 ± 3% -4.21% (p=0.000 n=91+92)
LinkJuju 4.48 ± 4% 4.21 ± 7% -6.08% (p=0.000 n=96+100)
name old MaxRSS new MaxRSS delta
LinkCmdGo 122k ± 2% 120k ± 4% -1.66% (p=0.000 n=98+93)
LinkJuju 799k ± 5% 865k ± 8% +8.29% (p=0.000 n=89+99)
GOGC=off
name old secs new secs delta
LinkCmdGo 0.42 ± 2% 0.41 ± 0% -2.98% (p=0.000 n=89+70)
LinkJuju 3.61 ± 0% 3.52 ± 1% -2.46% (p=0.000 n=80+89)
name old MaxRSS new MaxRSS delta
LinkCmdGo 130k ± 1% 128k ± 1% -1.33% (p=0.000 n=100+100)
LinkJuju 1.00M ± 0% 0.99M ± 0% -1.70% (p=0.000 n=100+100)
Change-Id: Ie08f6ccd4311bb78d8950548c678230a58635c73
Reviewed-on: https://go-review.googlesource.com/21026
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
The CMP* family of instructions are longer than their TEST counterparts by one byte.
After this change, my go tool has 13 cmp.*$0x0 instructions, compared to 5612 before.
Change-Id: Ieb87d65657917e494c0e4b711a7ba2918ae27610
Reviewed-on: https://go-review.googlesource.com/21255
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Simplify the handling of zero padding in fmt_integer and
fmt_float to not require any adjustment of the format flags.
Note that f.zero can only be true when padding to the left
and f.wid is always greater than or equal to 0.
Change-Id: I204b57d103c0eac13d86995992f2b26209196925
Reviewed-on: https://go-review.googlesource.com/21185
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
These are the first of several convenience
constructors for types.
They are part of type field encapsulation.
This removes most external writes to TARRAY Type and Bound fields.
substAny still directly fiddles with the .Type field.
substAny generally needs access to Type internals.
It will be moved to type.go in a future CL.
bimport still directly writes the .Type field.
This is hard to change.
Also of note:
* inl.go contains an (apparently irrelevant) bug fix:
as.Right was given the wrong type.
vararrtype was previously unused.
* I believe that aindex (subr.go) never creates slices,
but it is safer to keep existing behavior.
The removal of -1 as a constant there is part
of hiding that implementation detail.
Future CLs will finish that job.
Passes toolstash -cmp.
Change-Id: If09bf001a874d7dba08e9ad0bcd6722860af4b91
Reviewed-on: https://go-review.googlesource.com/21249
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Previously format argument was detected via scanning func type args.
This didn't work when func type couldn't be determined if the func
is declared in the external package. Fall back to scanning for
the first string call argument in this case.
Fixes#14754
Change-Id: I571cc29684cc641bc87882002ef474cf1481e9e2
Reviewed-on: https://go-review.googlesource.com/21023
Run-TryBot: Rob Pike <r@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
This is a change improving consistency in the source tree.
The pattern foo &= ^bar, was only used six times in src/ directory.
The usage of the supported &^ (bit clear / AND NOT) operator is way more
common, about factor 10x.
Change-Id: If26a2994fd81d23d42189bee00245eb84e672cf3
Reviewed-on: https://go-review.googlesource.com/21224
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
RFC 2047 recommends a maximum length of 75 characters for
encoded-words. Due to a bug, encoded-words were limited to 77
characters instead of 75.
Change-Id: I2ff9d013ab922df6fd542464ace70b1c46dc7ae7
Reviewed-on: https://go-review.googlesource.com/20918
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Add a "HuffmanOnly" compression level, where the input is
only entropy encoded.
The output is fully inflate compatible. Typical compression
is reduction is about 50% of typical level 1 compression, however
the compression time is very stable, and does not vary as much as
nearly as much level 1 compression (or Snappy).
This mode is useful for:
* HTTP compression in a CPU limited environment.
* Entropy encoding Snappy compressed data, for archiving, etc.
* Compression where compression time needs to be predictable.
* Fast network transfer.
Snappy "usually" performs inbetween this and level 1 compression-wise,
but at the same speed as "Huffman", so this is not a replacement,
but a good supplement for Snappy, since it usually can compress
Snappy output further.
This is implemented as level -2, since this would be too much of a
compression reduction to replace level 1.
>go test -bench=Encode -cpu=1
BenchmarkEncodeDigitsHuffman1e4 30000 52334 ns/op 191.08 MB/s
BenchmarkEncodeDigitsHuffman1e5 3000 518343 ns/op 192.92 MB/s
BenchmarkEncodeDigitsHuffman1e6 300 5356884 ns/op 186.68 MB/s
BenchmarkEncodeDigitsSpeed1e4 5000 324214 ns/op 30.84 MB/s
BenchmarkEncodeDigitsSpeed1e5 500 3952614 ns/op 25.30 MB/s
BenchmarkEncodeDigitsSpeed1e6 30 40760350 ns/op 24.53 MB/s
BenchmarkEncodeDigitsDefault1e4 5000 387056 ns/op 25.84 MB/s
BenchmarkEncodeDigitsDefault1e5 300 5950614 ns/op 16.80 MB/s
BenchmarkEncodeDigitsDefault1e6 20 63842195 ns/op 15.66 MB/s
BenchmarkEncodeDigitsCompress1e4 5000 391859 ns/op 25.52 MB/s
BenchmarkEncodeDigitsCompress1e5 300 5707112 ns/op 17.52 MB/s
BenchmarkEncodeDigitsCompress1e6 20 59839465 ns/op 16.71 MB/s
BenchmarkEncodeTwainHuffman1e4 20000 73498 ns/op 136.06 MB/s
BenchmarkEncodeTwainHuffman1e5 2000 595892 ns/op 167.82 MB/s
BenchmarkEncodeTwainHuffman1e6 200 6059016 ns/op 165.04 MB/s
BenchmarkEncodeTwainSpeed1e4 5000 321212 ns/op 31.13 MB/s
BenchmarkEncodeTwainSpeed1e5 500 2823873 ns/op 35.41 MB/s
BenchmarkEncodeTwainSpeed1e6 50 27237864 ns/op 36.71 MB/s
BenchmarkEncodeTwainDefault1e4 3000 454634 ns/op 22.00 MB/s
BenchmarkEncodeTwainDefault1e5 200 6859537 ns/op 14.58 MB/s
BenchmarkEncodeTwainDefault1e6 20 71547405 ns/op 13.98 MB/s
BenchmarkEncodeTwainCompress1e4 3000 462307 ns/op 21.63 MB/s
BenchmarkEncodeTwainCompress1e5 200 7534992 ns/op 13.27 MB/s
BenchmarkEncodeTwainCompress1e6 20 80353365 ns/op 12.45 MB/s
PASS
ok compress/flate 55.333s
Change-Id: I8e12ad13220e50d4cf7ddba6f292333efad61b0c
Reviewed-on: https://go-review.googlesource.com/20982
Reviewed-by: Joe Tsai <joetsai@digital-static.net>
Reviewed-by: Nigel Tao <nigeltao@golang.org>
