Commit 6ec96158 authored by ale's avatar ale

Update github.com/golang/snappy

parent 75efe505
Pipeline #11511 passed with stages
in 1 minute and 22 seconds
......@@ -5,6 +5,7 @@ go 1.14
require (
github.com/blevesearch/bleve v1.0.14
github.com/glycerine/go-unsnap-stream v0.0.0-20190730064659-98d31706395a // indirect
github.com/golang/snappy v0.0.2 // indirect
github.com/google/subcommands v1.2.0
github.com/gorilla/mux v1.6.3-0.20181030152528-3d80bc801bb0
github.com/meskio/epubgo v0.0.0-20160213181628-90dd5d78197f
......
......@@ -62,6 +62,8 @@ github.com/golang/protobuf v1.3.2/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5y
github.com/golang/snappy v0.0.0-20180518054509-2e65f85255db/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
github.com/golang/snappy v0.0.1 h1:Qgr9rKW7uDUkrbSmQeiDsGa8SjGyCOGtuasMWwvp2P4=
github.com/golang/snappy v0.0.1/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
github.com/golang/snappy v0.0.2 h1:aeE13tS0IiQgFjYdoL8qN3K1N2bXXtI6Vi51/y7BpMw=
github.com/golang/snappy v0.0.2/go.mod h1:/XxbfmMg8lxefKM7IXC3fBNl/7bRcc72aCRzEWrmP2Q=
github.com/google/subcommands v1.2.0 h1:vWQspBTo2nEqTUFita5/KeEWlUL8kQObDFbub/EN9oE=
github.com/google/subcommands v1.2.0/go.mod h1:ZjhPrFU+Olkh9WazFPsl27BQ4UPiG37m3yTrtFlrHVk=
github.com/gopherjs/gopherjs v0.0.0-20190910122728-9d188e94fb99 h1:twflg0XRTjwKpxb/jFExr4HGq6on2dEOmnL6FV+fgPw=
......@@ -114,6 +116,7 @@ github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+
github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJyk=
github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
github.com/syndtr/goleveldb v1.0.0 h1:fBdIW9lB4Iz0n9khmH8w27SJ3QEJ7+IgjPEwGSZiFdE=
github.com/syndtr/goleveldb v1.0.0/go.mod h1:ZVVdQEZoIme9iO1Ch2Jdy24qqXrMMOU6lpPAyBWyWuQ=
github.com/syndtr/goleveldb v1.0.1-0.20190625010220-02440ea7a285 h1:uSDYjYejelKyceA6DiCsngFof9jAyeaSyX9XC5a1a7Q=
github.com/syndtr/goleveldb v1.0.1-0.20190625010220-02440ea7a285/go.mod h1:9OrXJhf154huy1nPWmuSrkgjPUtUNhA+Zmy+6AESzuA=
......
......@@ -8,8 +8,10 @@
# Please keep the list sorted.
Amazon.com, Inc
Damian Gryski <dgryski@gmail.com>
Google Inc.
Jan Mercl <0xjnml@gmail.com>
Klaus Post <klauspost@gmail.com>
Rodolfo Carvalho <rhcarvalho@gmail.com>
Sebastien Binet <seb.binet@gmail.com>
......@@ -28,7 +28,9 @@
Damian Gryski <dgryski@gmail.com>
Jan Mercl <0xjnml@gmail.com>
Jonathan Swinney <jswinney@amazon.com>
Kai Backman <kaib@golang.org>
Klaus Post <klauspost@gmail.com>
Marc-Antoine Ruel <maruel@chromium.org>
Nigel Tao <nigeltao@golang.org>
Rob Pike <r@golang.org>
......
......@@ -52,6 +52,8 @@ const (
// Otherwise, a newly allocated slice will be returned.
//
// The dst and src must not overlap. It is valid to pass a nil dst.
//
// Decode handles the Snappy block format, not the Snappy stream format.
func Decode(dst, src []byte) ([]byte, error) {
dLen, s, err := decodedLen(src)
if err != nil {
......@@ -83,6 +85,8 @@ func NewReader(r io.Reader) *Reader {
}
// Reader is an io.Reader that can read Snappy-compressed bytes.
//
// Reader handles the Snappy stream format, not the Snappy block format.
type Reader struct {
r io.Reader
err error
......
// Copyright 2020 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.
// +build !appengine
// +build gc
// +build !noasm
#include "textflag.h"
// The asm code generally follows the pure Go code in decode_other.go, except
// where marked with a "!!!".
// func decode(dst, src []byte) int
//
// All local variables fit into registers. The non-zero stack size is only to
// spill registers and push args when issuing a CALL. The register allocation:
// - R2 scratch
// - R3 scratch
// - R4 length or x
// - R5 offset
// - R6 &src[s]
// - R7 &dst[d]
// + R8 dst_base
// + R9 dst_len
// + R10 dst_base + dst_len
// + R11 src_base
// + R12 src_len
// + R13 src_base + src_len
// - R14 used by doCopy
// - R15 used by doCopy
//
// The registers R8-R13 (marked with a "+") are set at the start of the
// function, and after a CALL returns, and are not otherwise modified.
//
// The d variable is implicitly R7 - R8, and len(dst)-d is R10 - R7.
// The s variable is implicitly R6 - R11, and len(src)-s is R13 - R6.
TEXT ·decode(SB), NOSPLIT, $56-56
// Initialize R6, R7 and R8-R13.
MOVD dst_base+0(FP), R8
MOVD dst_len+8(FP), R9
MOVD R8, R7
MOVD R8, R10
ADD R9, R10, R10
MOVD src_base+24(FP), R11
MOVD src_len+32(FP), R12
MOVD R11, R6
MOVD R11, R13
ADD R12, R13, R13
loop:
// for s < len(src)
CMP R13, R6
BEQ end
// R4 = uint32(src[s])
//
// switch src[s] & 0x03
MOVBU (R6), R4
MOVW R4, R3
ANDW $3, R3
MOVW $1, R1
CMPW R1, R3
BGE tagCopy
// ----------------------------------------
// The code below handles literal tags.
// case tagLiteral:
// x := uint32(src[s] >> 2)
// switch
MOVW $60, R1
ADD R4>>2, ZR, R4
CMPW R4, R1
BLS tagLit60Plus
// case x < 60:
// s++
ADD $1, R6, R6
doLit:
// This is the end of the inner "switch", when we have a literal tag.
//
// We assume that R4 == x and x fits in a uint32, where x is the variable
// used in the pure Go decode_other.go code.
// length = int(x) + 1
//
// Unlike the pure Go code, we don't need to check if length <= 0 because
// R4 can hold 64 bits, so the increment cannot overflow.
ADD $1, R4, R4
// Prepare to check if copying length bytes will run past the end of dst or
// src.
//
// R2 = len(dst) - d
// R3 = len(src) - s
MOVD R10, R2
SUB R7, R2, R2
MOVD R13, R3
SUB R6, R3, R3
// !!! Try a faster technique for short (16 or fewer bytes) copies.
//
// if length > 16 || len(dst)-d < 16 || len(src)-s < 16 {
// goto callMemmove // Fall back on calling runtime·memmove.
// }
//
// The C++ snappy code calls this TryFastAppend. It also checks len(src)-s
// against 21 instead of 16, because it cannot assume that all of its input
// is contiguous in memory and so it needs to leave enough source bytes to
// read the next tag without refilling buffers, but Go's Decode assumes
// contiguousness (the src argument is a []byte).
MOVD $16, R1
CMP R1, R4
BGT callMemmove
CMP R1, R2
BLT callMemmove
CMP R1, R3
BLT callMemmove
// !!! Implement the copy from src to dst as a 16-byte load and store.
// (Decode's documentation says that dst and src must not overlap.)
//
// This always copies 16 bytes, instead of only length bytes, but that's
// OK. If the input is a valid Snappy encoding then subsequent iterations
// will fix up the overrun. Otherwise, Decode returns a nil []byte (and a
// non-nil error), so the overrun will be ignored.
//
// Note that on arm64, it is legal and cheap to issue unaligned 8-byte or
// 16-byte loads and stores. This technique probably wouldn't be as
// effective on architectures that are fussier about alignment.
VLD1 0(R6), [V0.B16]
VST1 [V0.B16], 0(R7)
// d += length
// s += length
ADD R4, R7, R7
ADD R4, R6, R6
B loop
callMemmove:
// if length > len(dst)-d || length > len(src)-s { etc }
CMP R2, R4
BGT errCorrupt
CMP R3, R4
BGT errCorrupt
// copy(dst[d:], src[s:s+length])
//
// This means calling runtime·memmove(&dst[d], &src[s], length), so we push
// R7, R6 and R4 as arguments. Coincidentally, we also need to spill those
// three registers to the stack, to save local variables across the CALL.
MOVD R7, 8(RSP)
MOVD R6, 16(RSP)
MOVD R4, 24(RSP)
MOVD R7, 32(RSP)
MOVD R6, 40(RSP)
MOVD R4, 48(RSP)
CALL runtime·memmove(SB)
// Restore local variables: unspill registers from the stack and
// re-calculate R8-R13.
MOVD 32(RSP), R7
MOVD 40(RSP), R6
MOVD 48(RSP), R4
MOVD dst_base+0(FP), R8
MOVD dst_len+8(FP), R9
MOVD R8, R10
ADD R9, R10, R10
MOVD src_base+24(FP), R11
MOVD src_len+32(FP), R12
MOVD R11, R13
ADD R12, R13, R13
// d += length
// s += length
ADD R4, R7, R7
ADD R4, R6, R6
B loop
tagLit60Plus:
// !!! This fragment does the
//
// s += x - 58; if uint(s) > uint(len(src)) { etc }
//
// checks. In the asm version, we code it once instead of once per switch case.
ADD R4, R6, R6
SUB $58, R6, R6
MOVD R6, R3
SUB R11, R3, R3
CMP R12, R3
BGT errCorrupt
// case x == 60:
MOVW $61, R1
CMPW R1, R4
BEQ tagLit61
BGT tagLit62Plus
// x = uint32(src[s-1])
MOVBU -1(R6), R4
B doLit
tagLit61:
// case x == 61:
// x = uint32(src[s-2]) | uint32(src[s-1])<<8
MOVHU -2(R6), R4
B doLit
tagLit62Plus:
MOVW $62, R1
CMPW R1, R4
BHI tagLit63
// case x == 62:
// x = uint32(src[s-3]) | uint32(src[s-2])<<8 | uint32(src[s-1])<<16
MOVHU -3(R6), R4
MOVBU -1(R6), R3
ORR R3<<16, R4
B doLit
tagLit63:
// case x == 63:
// x = uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24
MOVWU -4(R6), R4
B doLit
// The code above handles literal tags.
// ----------------------------------------
// The code below handles copy tags.
tagCopy4:
// case tagCopy4:
// s += 5
ADD $5, R6, R6
// if uint(s) > uint(len(src)) { etc }
MOVD R6, R3
SUB R11, R3, R3
CMP R12, R3
BGT errCorrupt
// length = 1 + int(src[s-5])>>2
MOVD $1, R1
ADD R4>>2, R1, R4
// offset = int(uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24)
MOVWU -4(R6), R5
B doCopy
tagCopy2:
// case tagCopy2:
// s += 3
ADD $3, R6, R6
// if uint(s) > uint(len(src)) { etc }
MOVD R6, R3
SUB R11, R3, R3
CMP R12, R3
BGT errCorrupt
// length = 1 + int(src[s-3])>>2
MOVD $1, R1
ADD R4>>2, R1, R4
// offset = int(uint32(src[s-2]) | uint32(src[s-1])<<8)
MOVHU -2(R6), R5
B doCopy
tagCopy:
// We have a copy tag. We assume that:
// - R3 == src[s] & 0x03
// - R4 == src[s]
MOVD $2, R1
CMP R1, R3
BEQ tagCopy2
BGT tagCopy4
// case tagCopy1:
// s += 2
ADD $2, R6, R6
// if uint(s) > uint(len(src)) { etc }
MOVD R6, R3
SUB R11, R3, R3
CMP R12, R3
BGT errCorrupt
// offset = int(uint32(src[s-2])&0xe0<<3 | uint32(src[s-1]))
MOVD R4, R5
AND $0xe0, R5
MOVBU -1(R6), R3
ORR R5<<3, R3, R5
// length = 4 + int(src[s-2])>>2&0x7
MOVD $7, R1
AND R4>>2, R1, R4
ADD $4, R4, R4
doCopy:
// This is the end of the outer "switch", when we have a copy tag.
//
// We assume that:
// - R4 == length && R4 > 0
// - R5 == offset
// if offset <= 0 { etc }
MOVD $0, R1
CMP R1, R5
BLE errCorrupt
// if d < offset { etc }
MOVD R7, R3
SUB R8, R3, R3
CMP R5, R3
BLT errCorrupt
// if length > len(dst)-d { etc }
MOVD R10, R3
SUB R7, R3, R3
CMP R3, R4
BGT errCorrupt
// forwardCopy(dst[d:d+length], dst[d-offset:]); d += length
//
// Set:
// - R14 = len(dst)-d
// - R15 = &dst[d-offset]
MOVD R10, R14
SUB R7, R14, R14
MOVD R7, R15
SUB R5, R15, R15
// !!! Try a faster technique for short (16 or fewer bytes) forward copies.
//
// First, try using two 8-byte load/stores, similar to the doLit technique
// above. Even if dst[d:d+length] and dst[d-offset:] can overlap, this is
// still OK if offset >= 8. Note that this has to be two 8-byte load/stores
// and not one 16-byte load/store, and the first store has to be before the
// second load, due to the overlap if offset is in the range [8, 16).
//
// if length > 16 || offset < 8 || len(dst)-d < 16 {
// goto slowForwardCopy
// }
// copy 16 bytes
// d += length
MOVD $16, R1
MOVD $8, R0
CMP R1, R4
BGT slowForwardCopy
CMP R0, R5
BLT slowForwardCopy
CMP R1, R14
BLT slowForwardCopy
MOVD 0(R15), R2
MOVD R2, 0(R7)
MOVD 8(R15), R3
MOVD R3, 8(R7)
ADD R4, R7, R7
B loop
slowForwardCopy:
// !!! If the forward copy is longer than 16 bytes, or if offset < 8, we
// can still try 8-byte load stores, provided we can overrun up to 10 extra
// bytes. As above, the overrun will be fixed up by subsequent iterations
// of the outermost loop.
//
// The C++ snappy code calls this technique IncrementalCopyFastPath. Its
// commentary says:
//
// ----
//
// The main part of this loop is a simple copy of eight bytes at a time
// until we've copied (at least) the requested amount of bytes. However,
// if d and d-offset are less than eight bytes apart (indicating a
// repeating pattern of length < 8), we first need to expand the pattern in
// order to get the correct results. For instance, if the buffer looks like
// this, with the eight-byte <d-offset> and <d> patterns marked as
// intervals:
//
// abxxxxxxxxxxxx
// [------] d-offset
// [------] d
//
// a single eight-byte copy from <d-offset> to <d> will repeat the pattern
// once, after which we can move <d> two bytes without moving <d-offset>:
//
// ababxxxxxxxxxx
// [------] d-offset
// [------] d
//
// and repeat the exercise until the two no longer overlap.
//
// This allows us to do very well in the special case of one single byte
// repeated many times, without taking a big hit for more general cases.
//
// The worst case of extra writing past the end of the match occurs when
// offset == 1 and length == 1; the last copy will read from byte positions
// [0..7] and write to [4..11], whereas it was only supposed to write to
// position 1. Thus, ten excess bytes.
//
// ----
//
// That "10 byte overrun" worst case is confirmed by Go's
// TestSlowForwardCopyOverrun, which also tests the fixUpSlowForwardCopy
// and finishSlowForwardCopy algorithm.
//
// if length > len(dst)-d-10 {
// goto verySlowForwardCopy
// }
SUB $10, R14, R14
CMP R14, R4
BGT verySlowForwardCopy
makeOffsetAtLeast8:
// !!! As above, expand the pattern so that offset >= 8 and we can use
// 8-byte load/stores.
//
// for offset < 8 {
// copy 8 bytes from dst[d-offset:] to dst[d:]
// length -= offset
// d += offset
// offset += offset
// // The two previous lines together means that d-offset, and therefore
// // R15, is unchanged.
// }
MOVD $8, R1
CMP R1, R5
BGE fixUpSlowForwardCopy
MOVD (R15), R3
MOVD R3, (R7)
SUB R5, R4, R4
ADD R5, R7, R7
ADD R5, R5, R5
B makeOffsetAtLeast8
fixUpSlowForwardCopy:
// !!! Add length (which might be negative now) to d (implied by R7 being
// &dst[d]) so that d ends up at the right place when we jump back to the
// top of the loop. Before we do that, though, we save R7 to R2 so that, if
// length is positive, copying the remaining length bytes will write to the
// right place.
MOVD R7, R2
ADD R4, R7, R7
finishSlowForwardCopy:
// !!! Repeat 8-byte load/stores until length <= 0. Ending with a negative
// length means that we overrun, but as above, that will be fixed up by
// subsequent iterations of the outermost loop.
MOVD $0, R1
CMP R1, R4
BLE loop
MOVD (R15), R3
MOVD R3, (R2)
ADD $8, R15, R15
ADD $8, R2, R2
SUB $8, R4, R4
B finishSlowForwardCopy
verySlowForwardCopy:
// verySlowForwardCopy is a simple implementation of forward copy. In C
// parlance, this is a do/while loop instead of a while loop, since we know
// that length > 0. In Go syntax:
//
// for {
// dst[d] = dst[d - offset]
// d++
// length--
// if length == 0 {
// break
// }
// }
MOVB (R15), R3
MOVB R3, (R7)
ADD $1, R15, R15
ADD $1, R7, R7
SUB $1, R4, R4
MOVD $0, R1
CMP R1, R4
BNE verySlowForwardCopy
B loop
// The code above handles copy tags.
// ----------------------------------------
end:
// This is the end of the "for s < len(src)".
//
// if d != len(dst) { etc }
CMP R10, R7
BNE errCorrupt
// return 0
MOVD $0, ret+48(FP)
RET
errCorrupt:
// return decodeErrCodeCorrupt
MOVD $1, R2
MOVD R2, ret+48(FP)
RET
......@@ -5,6 +5,7 @@
// +build !appengine
// +build gc
// +build !noasm
// +build amd64 arm64
package snappy
......
......@@ -2,7 +2,7 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.