Make Nix builds work

1 files changed, 1106 insertions, 0 deletions

diff --git a/vendor/github.com/klauspost/compress/s2/encode_better.go b/vendor/github.com/klauspost/compress/s2/encode_better.go
new file mode 100644
index 0000000..544cb1e
--- /dev/null
+++ b/vendor/github.com/klauspost/compress/s2/encode_better.go
@@ -0,0 +1,1106 @@
+// Copyright 2016 The Snappy-Go Authors. All rights reserved.
+// Copyright (c) 2019 Klaus Post. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package s2
+
+import (
+        "bytes"
+        "fmt"
+        "math/bits"
+)
+
+// hash4 returns the hash of the lowest 4 bytes of u to fit in a hash table with h bits.
+// Preferably h should be a constant and should always be <32.
+func hash4(u uint64, h uint8) uint32 {
+        const prime4bytes = 2654435761
+        return (uint32(u) * prime4bytes) >> ((32 - h) & 31)
+}
+
+// hash5 returns the hash of the lowest 5 bytes of u to fit in a hash table with h bits.
+// Preferably h should be a constant and should always be <64.
+func hash5(u uint64, h uint8) uint32 {
+        const prime5bytes = 889523592379
+        return uint32(((u << (64 - 40)) * prime5bytes) >> ((64 - h) & 63))
+}
+
+// hash7 returns the hash of the lowest 7 bytes of u to fit in a hash table with h bits.
+// Preferably h should be a constant and should always be <64.
+func hash7(u uint64, h uint8) uint32 {
+        const prime7bytes = 58295818150454627
+        return uint32(((u << (64 - 56)) * prime7bytes) >> ((64 - h) & 63))
+}
+
+// hash8 returns the hash of u to fit in a hash table with h bits.
+// Preferably h should be a constant and should always be <64.
+func hash8(u uint64, h uint8) uint32 {
+        const prime8bytes = 0xcf1bbcdcb7a56463
+        return uint32((u * prime8bytes) >> ((64 - h) & 63))
+}
+
+// encodeBlockBetter encodes a non-empty src to a guaranteed-large-enough dst. It
+// assumes that the varint-encoded length of the decompressed bytes has already
+// been written.
+//
+// It also assumes that:
+//
+//      len(dst) >= MaxEncodedLen(len(src)) &&
+//      minNonLiteralBlockSize <= len(src) && len(src) <= maxBlockSize
+func encodeBlockBetterGo(dst, src []byte) (d int) {
+        // sLimit is when to stop looking for offset/length copies. The inputMargin
+        // lets us use a fast path for emitLiteral in the main loop, while we are
+        // looking for copies.
+        sLimit := len(src) - inputMargin
+        if len(src) < minNonLiteralBlockSize {
+                return 0
+        }
+
+        // Initialize the hash tables.
+        const (
+                // Long hash matches.
+                lTableBits    = 17
+                maxLTableSize = 1 << lTableBits
+
+                // Short hash matches.
+                sTableBits    = 14
+                maxSTableSize = 1 << sTableBits
+        )
+
+        var lTable [maxLTableSize]uint32
+        var sTable [maxSTableSize]uint32
+
+        // Bail if we can't compress to at least this.
+        dstLimit := len(src) - len(src)>>5 - 6
+
+        // nextEmit is where in src the next emitLiteral should start from.
+        nextEmit := 0
+
+        // The encoded form must start with a literal, as there are no previous
+        // bytes to copy, so we start looking for hash matches at s == 1.
+        s := 1
+        cv := load64(src, s)
+
+        // We initialize repeat to 0, so we never match on first attempt
+        repeat := 0
+
+        for {
+                candidateL := 0
+                nextS := 0
+                for {
+                        // Next src position to check
+                        nextS = s + (s-nextEmit)>>7 + 1
+                        if nextS > sLimit {
+                                goto emitRemainder
+                        }
+                        hashL := hash7(cv, lTableBits)
+                        hashS := hash4(cv, sTableBits)
+                        candidateL = int(lTable[hashL])
+                        candidateS := int(sTable[hashS])
+                        lTable[hashL] = uint32(s)
+                        sTable[hashS] = uint32(s)
+
+                        valLong := load64(src, candidateL)
+                        valShort := load64(src, candidateS)
+
+                        // If long matches at least 8 bytes, use that.
+                        if cv == valLong {
+                                break
+                        }
+                        if cv == valShort {
+                                candidateL = candidateS
+                                break
+                        }
+
+                        // Check repeat at offset checkRep.
+                        const checkRep = 1
+                        // Minimum length of a repeat. Tested with various values.
+                        // While 4-5 offers improvements in some, 6 reduces
+                        // regressions significantly.
+                        const wantRepeatBytes = 6
+                        const repeatMask = ((1 << (wantRepeatBytes * 8)) - 1) << (8 * checkRep)
+                        if false && repeat > 0 && cv&repeatMask == load64(src, s-repeat)&repeatMask {
+                                base := s + checkRep
+                                // Extend back
+                                for i := base - repeat; base > nextEmit && i > 0 && src[i-1] == src[base-1]; {
+                                        i--
+                                        base--
+                                }
+                                d += emitLiteral(dst[d:], src[nextEmit:base])
+
+                                // Extend forward
+                                candidate := s - repeat + wantRepeatBytes + checkRep
+                                s += wantRepeatBytes + checkRep
+                                for s < len(src) {
+                                        if len(src)-s < 8 {
+                                                if src[s] == src[candidate] {
+                                                        s++
+                                                        candidate++
+                                                        continue
+                                                }
+                                                break
+                                        }
+                                        if diff := load64(src, s) ^ load64(src, candidate); diff != 0 {
+                                                s += bits.TrailingZeros64(diff) >> 3
+                                                break
+                                        }
+                                        s += 8
+                                        candidate += 8
+                                }
+                                // same as `add := emitCopy(dst[d:], repeat, s-base)` but skips storing offset.
+                                d += emitRepeat(dst[d:], repeat, s-base)
+                                nextEmit = s
+                                if s >= sLimit {
+                                        goto emitRemainder
+                                }
+                                // Index in-between
+                                index0 := base + 1
+                                index1 := s - 2
+
+                                for index0 < index1 {
+                                        cv0 := load64(src, index0)
+                                        cv1 := load64(src, index1)
+                                        lTable[hash7(cv0, lTableBits)] = uint32(index0)
+                                        sTable[hash4(cv0>>8, sTableBits)] = uint32(index0 + 1)
+
+                                        lTable[hash7(cv1, lTableBits)] = uint32(index1)
+                                        sTable[hash4(cv1>>8, sTableBits)] = uint32(index1 + 1)
+                                        index0 += 2
+                                        index1 -= 2
+                                }
+
+                                cv = load64(src, s)
+                                continue
+                        }
+
+                        // Long likely matches 7, so take that.
+                        if uint32(cv) == uint32(valLong) {
+                                break
+                        }
+
+                        // Check our short candidate
+                        if uint32(cv) == uint32(valShort) {
+                                // Try a long candidate at s+1
+                                hashL = hash7(cv>>8, lTableBits)
+                                candidateL = int(lTable[hashL])
+                                lTable[hashL] = uint32(s + 1)
+                                if uint32(cv>>8) == load32(src, candidateL) {
+                                        s++
+                                        break
+                                }
+                                // Use our short candidate.
+                                candidateL = candidateS
+                                break
+                        }
+
+                        cv = load64(src, nextS)
+                        s = nextS
+                }
+
+                // Extend backwards
+                for candidateL > 0 && s > nextEmit && src[candidateL-1] == src[s-1] {
+                        candidateL--
+                        s--
+                }
+
+                // Bail if we exceed the maximum size.
+                if d+(s-nextEmit) > dstLimit {
+                        return 0
+                }
+
+                base := s
+                offset := base - candidateL
+
+                // Extend the 4-byte match as long as possible.
+                s += 4
+                candidateL += 4
+                for s < len(src) {
+                        if len(src)-s < 8 {
+                                if src[s] == src[candidateL] {
+                                        s++
+                                        candidateL++
+                                        continue
+                                }
+                                break
+                        }
+                        if diff := load64(src, s) ^ load64(src, candidateL); diff != 0 {
+                                s += bits.TrailingZeros64(diff) >> 3
+                                break
+                        }
+                        s += 8
+                        candidateL += 8
+                }
+
+                if offset > 65535 && s-base <= 5 && repeat != offset {
+                        // Bail if the match is equal or worse to the encoding.
+                        s = nextS + 1
+                        if s >= sLimit {
+                                goto emitRemainder
+                        }
+                        cv = load64(src, s)
+                        continue
+                }
+
+                d += emitLiteral(dst[d:], src[nextEmit:base])
+                if repeat == offset {
+                        d += emitRepeat(dst[d:], offset, s-base)
+                } else {
+                        d += emitCopy(dst[d:], offset, s-base)
+                        repeat = offset
+                }
+
+                nextEmit = s
+                if s >= sLimit {
+                        goto emitRemainder
+                }
+
+                if d > dstLimit {
+                        // Do we have space for more, if not bail.
+                        return 0
+                }
+
+                // Index short & long
+                index0 := base + 1
+                index1 := s - 2
+
+                cv0 := load64(src, index0)
+                cv1 := load64(src, index1)
+                lTable[hash7(cv0, lTableBits)] = uint32(index0)
+                sTable[hash4(cv0>>8, sTableBits)] = uint32(index0 + 1)
+
+                // lTable could be postponed, but very minor difference.
+                lTable[hash7(cv1, lTableBits)] = uint32(index1)
+                sTable[hash4(cv1>>8, sTableBits)] = uint32(index1 + 1)
+                index0 += 1
+                index1 -= 1
+                cv = load64(src, s)
+
+                // Index large values sparsely in between.
+                // We do two starting from different offsets for speed.
+                index2 := (index0 + index1 + 1) >> 1
+                for index2 < index1 {
+                        lTable[hash7(load64(src, index0), lTableBits)] = uint32(index0)
+                        lTable[hash7(load64(src, index2), lTableBits)] = uint32(index2)
+                        index0 += 2
+                        index2 += 2
+                }
+        }
+
+emitRemainder:
+        if nextEmit < len(src) {
+                // Bail if we exceed the maximum size.
+                if d+len(src)-nextEmit > dstLimit {
+                        return 0
+                }
+                d += emitLiteral(dst[d:], src[nextEmit:])
+        }
+        return d
+}
+
+// encodeBlockBetterSnappyGo encodes a non-empty src to a guaranteed-large-enough dst. It
+// assumes that the varint-encoded length of the decompressed bytes has already
+// been written.
+//
+// It also assumes that:
+//
+//      len(dst) >= MaxEncodedLen(len(src)) &&
+//      minNonLiteralBlockSize <= len(src) && len(src) <= maxBlockSize
+func encodeBlockBetterSnappyGo(dst, src []byte) (d int) {
+        // sLimit is when to stop looking for offset/length copies. The inputMargin
+        // lets us use a fast path for emitLiteral in the main loop, while we are
+        // looking for copies.
+        sLimit := len(src) - inputMargin
+        if len(src) < minNonLiteralBlockSize {
+                return 0
+        }
+
+        // Initialize the hash tables.
+        const (
+                // Long hash matches.
+                lTableBits    = 16
+                maxLTableSize = 1 << lTableBits
+
+                // Short hash matches.
+                sTableBits    = 14
+                maxSTableSize = 1 << sTableBits
+        )
+
+        var lTable [maxLTableSize]uint32
+        var sTable [maxSTableSize]uint32
+
+        // Bail if we can't compress to at least this.
+        dstLimit := len(src) - len(src)>>5 - 6
+
+        // nextEmit is where in src the next emitLiteral should start from.
+        nextEmit := 0
+
+        // The encoded form must start with a literal, as there are no previous
+        // bytes to copy, so we start looking for hash matches at s == 1.
+        s := 1
+        cv := load64(src, s)
+
+        // We initialize repeat to 0, so we never match on first attempt
+        repeat := 0
+        const maxSkip = 100
+
+        for {
+                candidateL := 0
+                nextS := 0
+                for {
+                        // Next src position to check
+                        nextS = (s-nextEmit)>>7 + 1
+                        if nextS > maxSkip {
+                                nextS = s + maxSkip
+                        } else {
+                                nextS += s
+                        }
+
+                        if nextS > sLimit {
+                                goto emitRemainder
+                        }
+                        hashL := hash7(cv, lTableBits)
+                        hashS := hash4(cv, sTableBits)
+                        candidateL = int(lTable[hashL])
+                        candidateS := int(sTable[hashS])
+                        lTable[hashL] = uint32(s)
+                        sTable[hashS] = uint32(s)
+
+                        if uint32(cv) == load32(src, candidateL) {
+                                break
+                        }
+
+                        // Check our short candidate
+                        if uint32(cv) == load32(src, candidateS) {
+                                // Try a long candidate at s+1
+                                hashL = hash7(cv>>8, lTableBits)
+                                candidateL = int(lTable[hashL])
+                                lTable[hashL] = uint32(s + 1)
+                                if uint32(cv>>8) == load32(src, candidateL) {
+                                        s++
+                                        break
+                                }
+                                // Use our short candidate.
+                                candidateL = candidateS
+                                break
+                        }
+
+                        cv = load64(src, nextS)
+                        s = nextS
+                }
+
+                // Extend backwards
+                for candidateL > 0 && s > nextEmit && src[candidateL-1] == src[s-1] {
+                        candidateL--
+                        s--
+                }
+
+                // Bail if we exceed the maximum size.
+                if d+(s-nextEmit) > dstLimit {
+                        return 0
+                }
+
+                base := s
+                offset := base - candidateL
+
+                // Extend the 4-byte match as long as possible.
+                s += 4
+                candidateL += 4
+                for s < len(src) {
+                        if len(src)-s < 8 {
+                                if src[s] == src[candidateL] {
+                                        s++
+                                        candidateL++
+                                        continue
+                                }
+                                break
+                        }
+                        if diff := load64(src, s) ^ load64(src, candidateL); diff != 0 {
+                                s += bits.TrailingZeros64(diff) >> 3
+                                break
+                        }
+                        s += 8
+                        candidateL += 8
+                }
+
+                if offset > 65535 && s-base <= 5 && repeat != offset {
+                        // Bail if the match is equal or worse to the encoding.
+                        s = nextS + 1
+                        if s >= sLimit {
+                                goto emitRemainder
+                        }
+                        cv = load64(src, s)
+                        continue
+                }
+
+                d += emitLiteral(dst[d:], src[nextEmit:base])
+                d += emitCopyNoRepeat(dst[d:], offset, s-base)
+                repeat = offset
+
+                nextEmit = s
+                if s >= sLimit {
+                        goto emitRemainder
+                }
+
+                if d > dstLimit {
+                        // Do we have space for more, if not bail.
+                        return 0
+                }
+
+                // Index short & long
+                index0 := base + 1
+                index1 := s - 2
+
+                cv0 := load64(src, index0)
+                cv1 := load64(src, index1)
+                lTable[hash7(cv0, lTableBits)] = uint32(index0)
+                sTable[hash4(cv0>>8, sTableBits)] = uint32(index0 + 1)
+
+                lTable[hash7(cv1, lTableBits)] = uint32(index1)
+                sTable[hash4(cv1>>8, sTableBits)] = uint32(index1 + 1)
+                index0 += 1
+                index1 -= 1
+                cv = load64(src, s)
+
+                // Index large values sparsely in between.
+                // We do two starting from different offsets for speed.
+                index2 := (index0 + index1 + 1) >> 1
+                for index2 < index1 {
+                        lTable[hash7(load64(src, index0), lTableBits)] = uint32(index0)
+                        lTable[hash7(load64(src, index2), lTableBits)] = uint32(index2)
+                        index0 += 2
+                        index2 += 2
+                }
+        }
+
+emitRemainder:
+        if nextEmit < len(src) {
+                // Bail if we exceed the maximum size.
+                if d+len(src)-nextEmit > dstLimit {
+                        return 0
+                }
+                d += emitLiteral(dst[d:], src[nextEmit:])
+        }
+        return d
+}
+
+// encodeBlockBetterDict encodes a non-empty src to a guaranteed-large-enough dst. It
+// assumes that the varint-encoded length of the decompressed bytes has already
+// been written.
+//
+// It also assumes that:
+//
+//      len(dst) >= MaxEncodedLen(len(src)) &&
+//      minNonLiteralBlockSize <= len(src) && len(src) <= maxBlockSize
+func encodeBlockBetterDict(dst, src []byte, dict *Dict) (d int) {
+        // sLimit is when to stop looking for offset/length copies. The inputMargin
+        // lets us use a fast path for emitLiteral in the main loop, while we are
+        // looking for copies.
+        // Initialize the hash tables.
+        const (
+                // Long hash matches.
+                lTableBits    = 17
+                maxLTableSize = 1 << lTableBits
+
+                // Short hash matches.
+                sTableBits    = 14
+                maxSTableSize = 1 << sTableBits
+
+                maxAhead = 8 // maximum bytes ahead without checking sLimit
+
+                debug = false
+        )
+
+        sLimit := len(src) - inputMargin
+        if sLimit > MaxDictSrcOffset-maxAhead {
+                sLimit = MaxDictSrcOffset - maxAhead
+        }
+        if len(src) < minNonLiteralBlockSize {
+                return 0
+        }
+
+        dict.initBetter()
+
+        var lTable [maxLTableSize]uint32
+        var sTable [maxSTableSize]uint32
+
+        // Bail if we can't compress to at least this.
+        dstLimit := len(src) - len(src)>>5 - 6
+
+        // nextEmit is where in src the next emitLiteral should start from.
+        nextEmit := 0
+
+        // The encoded form must start with a literal, as there are no previous
+        // bytes to copy, so we start looking for hash matches at s == 1.
+        s := 0
+        cv := load64(src, s)
+
+        // We initialize repeat to 0, so we never match on first attempt
+        repeat := len(dict.dict) - dict.repeat
+
+        // While in dict
+searchDict:
+        for {
+                candidateL := 0
+                nextS := 0
+                for {
+                        // Next src position to check
+                        nextS = s + (s-nextEmit)>>7 + 1
+                        if nextS > sLimit {
+                                break searchDict
+                        }
+                        hashL := hash7(cv, lTableBits)
+                        hashS := hash4(cv, sTableBits)
+                        candidateL = int(lTable[hashL])
+                        candidateS := int(sTable[hashS])
+                        dictL := int(dict.betterTableLong[hashL])
+                        dictS := int(dict.betterTableShort[hashS])
+                        lTable[hashL] = uint32(s)
+                        sTable[hashS] = uint32(s)
+
+                        valLong := load64(src, candidateL)
+                        valShort := load64(src, candidateS)
+
+                        // If long matches at least 8 bytes, use that.
+                        if s != 0 {
+                                if cv == valLong {
+                                        goto emitMatch
+                                }
+                                if cv == valShort {
+                                        candidateL = candidateS
+                                        goto emitMatch
+                                }
+                        }
+
+                        // Check dict repeat.
+                        if repeat >= s+4 {
+                                candidate := len(dict.dict) - repeat + s
+                                if candidate > 0 && uint32(cv) == load32(dict.dict, candidate) {
+                                        // Extend back
+                                        base := s
+                                        for i := candidate; base > nextEmit && i > 0 && dict.dict[i-1] == src[base-1]; {
+                                                i--
+                                                base--
+                                        }
+                                        d += emitLiteral(dst[d:], src[nextEmit:base])
+                                        if debug && nextEmit != base {
+                                                fmt.Println("emitted ", base-nextEmit, "literals")
+                                        }
+                                        s += 4
+                                        candidate += 4
+                                        for candidate < len(dict.dict)-8 && s <= len(src)-8 {
+                                                if diff := load64(src, s) ^ load64(dict.dict, candidate); diff != 0 {
+                                                        s += bits.TrailingZeros64(diff) >> 3
+                                                        break
+                                                }
+                                                s += 8
+                                                candidate += 8
+                                        }
+                                        d += emitRepeat(dst[d:], repeat, s-base)
+                                        if debug {
+                                                fmt.Println("emitted dict repeat length", s-base, "offset:", repeat, "s:", s)
+                                        }
+                                        nextEmit = s
+                                        if s >= sLimit {
+                                                break searchDict
+                                        }
+                                        // Index in-between
+                                        index0 := base + 1
+                                        index1 := s - 2
+
+                                        cv = load64(src, s)
+                                        for index0 < index1 {
+                                                cv0 := load64(src, index0)
+                                                cv1 := load64(src, index1)
+                                                lTable[hash7(cv0, lTableBits)] = uint32(index0)
+                                                sTable[hash4(cv0>>8, sTableBits)] = uint32(index0 + 1)
+
+                                                lTable[hash7(cv1, lTableBits)] = uint32(index1)
+                                                sTable[hash4(cv1>>8, sTableBits)] = uint32(index1 + 1)
+                                                index0 += 2
+                                                index1 -= 2
+                                        }
+                                        continue
+                                }
+                        }
+                        // Don't try to find match at s==0
+                        if s == 0 {
+                                cv = load64(src, nextS)
+                                s = nextS
+                                continue
+                        }
+
+                        // Long likely matches 7, so take that.
+                        if uint32(cv) == uint32(valLong) {
+                                goto emitMatch
+                        }
+
+                        // Long dict...
+                        if uint32(cv) == load32(dict.dict, dictL) {
+                                candidateL = dictL
+                                goto emitDict
+                        }
+
+                        // Check our short candidate
+                        if uint32(cv) == uint32(valShort) {
+                                // Try a long candidate at s+1
+                                hashL = hash7(cv>>8, lTableBits)
+                                candidateL = int(lTable[hashL])
+                                lTable[hashL] = uint32(s + 1)
+                                if uint32(cv>>8) == load32(src, candidateL) {
+                                        s++
+                                        goto emitMatch
+                                }
+                                // Use our short candidate.
+                                candidateL = candidateS
+                                goto emitMatch
+                        }
+                        if uint32(cv) == load32(dict.dict, dictS) {
+                                // Try a long candidate at s+1
+                                hashL = hash7(cv>>8, lTableBits)
+                                candidateL = int(lTable[hashL])
+                                lTable[hashL] = uint32(s + 1)
+                                if uint32(cv>>8) == load32(src, candidateL) {
+                                        s++
+                                        goto emitMatch
+                                }
+                                candidateL = dictS
+                                goto emitDict
+                        }
+                        cv = load64(src, nextS)
+                        s = nextS
+                }
+        emitDict:
+                {
+                        if debug {
+                                if load32(dict.dict, candidateL) != load32(src, s) {
+                                        panic("dict emit mismatch")
+                                }
+                        }
+                        // Extend backwards.
+                        // The top bytes will be rechecked to get the full match.
+                        for candidateL > 0 && s > nextEmit && dict.dict[candidateL-1] == src[s-1] {
+                                candidateL--
+                                s--
+                        }
+
+                        // Bail if we exceed the maximum size.
+                        if d+(s-nextEmit) > dstLimit {
+                                return 0
+                        }
+
+                        // A 4-byte match has been found. We'll later see if more than 4 bytes
+                        // match. But, prior to the match, src[nextEmit:s] are unmatched. Emit
+                        // them as literal bytes.
+
+                        d += emitLiteral(dst[d:], src[nextEmit:s])
+                        if debug && nextEmit != s {
+                                fmt.Println("emitted ", s-nextEmit, "literals")
+                        }
+                        {
+                                // Invariant: we have a 4-byte match at s, and no need to emit any
+                                // literal bytes prior to s.
+                                base := s
+                                offset := s + (len(dict.dict)) - candidateL
+
+                                // Extend the 4-byte match as long as possible.
+                                s += 4
+                                candidateL += 4
+                                for s <= len(src)-8 && len(dict.dict)-candidateL >= 8 {
+                                        if diff := load64(src, s) ^ load64(dict.dict, candidateL); diff != 0 {
+                                                s += bits.TrailingZeros64(diff) >> 3
+                                                break
+                                        }
+                                        s += 8
+                                        candidateL += 8
+                                }
+
+                                if repeat == offset {
+                                        if debug {
+                                                fmt.Println("emitted dict repeat, length", s-base, "offset:", offset, "s:", s, "dict offset:", candidateL)
+                                        }
+                                        d += emitRepeat(dst[d:], offset, s-base)
+                                } else {
+                                        if debug {
+                                                fmt.Println("emitted dict copy, length", s-base, "offset:", offset, "s:", s, "dict offset:", candidateL)
+                                        }
+                                        // Matches longer than 64 are split.
+                                        if s <= sLimit || s-base < 8 {
+                                                d += emitCopy(dst[d:], offset, s-base)
+                                        } else {
+                                                // Split to ensure we don't start a copy within next block.
+                                                d += emitCopy(dst[d:], offset, 4)
+                                                d += emitRepeat(dst[d:], offset, s-base-4)
+                                        }
+                                        repeat = offset
+                                }
+                                if false {
+                                        // Validate match.
+                                        if s <= candidateL {
+                                                panic("s <= candidate")
+                                        }
+                                        a := src[base:s]
+                                        b := dict.dict[base-repeat : base-repeat+(s-base)]
+                                        if !bytes.Equal(a, b) {
+                                                panic("mismatch")
+                                        }
+                                }
+
+                                nextEmit = s
+                                if s >= sLimit {
+                                        break searchDict
+                                }
+
+                                if d > dstLimit {
+                                        // Do we have space for more, if not bail.
+                                        return 0
+                                }
+
+                                // Index short & long
+                                index0 := base + 1
+                                index1 := s - 2
+
+                                cv0 := load64(src, index0)
+                                cv1 := load64(src, index1)
+                                lTable[hash7(cv0, lTableBits)] = uint32(index0)
+                                sTable[hash4(cv0>>8, sTableBits)] = uint32(index0 + 1)
+
+                                lTable[hash7(cv1, lTableBits)] = uint32(index1)
+                                sTable[hash4(cv1>>8, sTableBits)] = uint32(index1 + 1)
+                                index0 += 1
+                                index1 -= 1
+                                cv = load64(src, s)
+
+                                // index every second long in between.
+                                for index0 < index1 {
+                                        lTable[hash7(load64(src, index0), lTableBits)] = uint32(index0)
+                                        lTable[hash7(load64(src, index1), lTableBits)] = uint32(index1)
+                                        index0 += 2
+                                        index1 -= 2
+                                }
+                        }
+                        continue
+                }
+        emitMatch:
+
+                // Extend backwards
+                for candidateL > 0 && s > nextEmit && src[candidateL-1] == src[s-1] {
+                        candidateL--
+                        s--
+                }
+
+                // Bail if we exceed the maximum size.
+                if d+(s-nextEmit) > dstLimit {
+                        return 0
+                }
+
+                base := s
+                offset := base - candidateL
+
+                // Extend the 4-byte match as long as possible.
+                s += 4
+                candidateL += 4
+                for s < len(src) {
+                        if len(src)-s < 8 {
+                                if src[s] == src[candidateL] {
+                                        s++
+                                        candidateL++
+                                        continue
+                                }
+                                break
+                        }
+                        if diff := load64(src, s) ^ load64(src, candidateL); diff != 0 {
+                                s += bits.TrailingZeros64(diff) >> 3
+                                break
+                        }
+                        s += 8
+                        candidateL += 8
+                }
+
+                if offset > 65535 && s-base <= 5 && repeat != offset {
+                        // Bail if the match is equal or worse to the encoding.
+                        s = nextS + 1
+                        if s >= sLimit {
+                                goto emitRemainder
+                        }
+                        cv = load64(src, s)
+                        continue
+                }
+
+                d += emitLiteral(dst[d:], src[nextEmit:base])
+                if debug && nextEmit != s {
+                        fmt.Println("emitted ", s-nextEmit, "literals")
+                }
+                if repeat == offset {
+                        if debug {
+                                fmt.Println("emitted match repeat, length", s-base, "offset:", offset, "s:", s)
+                        }
+                        d += emitRepeat(dst[d:], offset, s-base)
+                } else {
+                        if debug {
+                                fmt.Println("emitted match copy, length", s-base, "offset:", offset, "s:", s)
+                        }
+                        d += emitCopy(dst[d:], offset, s-base)
+                        repeat = offset
+                }
+
+                nextEmit = s
+                if s >= sLimit {
+                        goto emitRemainder
+                }
+
+                if d > dstLimit {
+                        // Do we have space for more, if not bail.
+                        return 0
+                }
+
+                // Index short & long
+                index0 := base + 1
+                index1 := s - 2
+
+                cv0 := load64(src, index0)
+                cv1 := load64(src, index1)
+                lTable[hash7(cv0, lTableBits)] = uint32(index0)
+                sTable[hash4(cv0>>8, sTableBits)] = uint32(index0 + 1)
+
+                lTable[hash7(cv1, lTableBits)] = uint32(index1)
+                sTable[hash4(cv1>>8, sTableBits)] = uint32(index1 + 1)
+                index0 += 1
+                index1 -= 1
+                cv = load64(src, s)
+
+                // Index large values sparsely in between.
+                // We do two starting from different offsets for speed.
+                index2 := (index0 + index1 + 1) >> 1
+                for index2 < index1 {
+                        lTable[hash7(load64(src, index0), lTableBits)] = uint32(index0)
+                        lTable[hash7(load64(src, index2), lTableBits)] = uint32(index2)
+                        index0 += 2
+                        index2 += 2
+                }
+        }
+
+        // Search without dict:
+        if repeat > s {
+                repeat = 0
+        }
+
+        // No more dict
+        sLimit = len(src) - inputMargin
+        if s >= sLimit {
+                goto emitRemainder
+        }
+        cv = load64(src, s)
+        if debug {
+                fmt.Println("now", s, "->", sLimit, "out:", d, "left:", len(src)-s, "nextemit:", nextEmit, "dstLimit:", dstLimit, "s:", s)
+        }
+        for {
+                candidateL := 0
+                nextS := 0
+                for {
+                        // Next src position to check
+                        nextS = s + (s-nextEmit)>>7 + 1
+                        if nextS > sLimit {
+                                goto emitRemainder
+                        }
+                        hashL := hash7(cv, lTableBits)
+                        hashS := hash4(cv, sTableBits)
+                        candidateL = int(lTable[hashL])
+                        candidateS := int(sTable[hashS])
+                        lTable[hashL] = uint32(s)
+                        sTable[hashS] = uint32(s)
+
+                        valLong := load64(src, candidateL)
+                        valShort := load64(src, candidateS)
+
+                        // If long matches at least 8 bytes, use that.
+                        if cv == valLong {
+                                break
+                        }
+                        if cv == valShort {
+                                candidateL = candidateS
+                                break
+                        }
+
+                        // Check repeat at offset checkRep.
+                        const checkRep = 1
+                        // Minimum length of a repeat. Tested with various values.
+                        // While 4-5 offers improvements in some, 6 reduces
+                        // regressions significantly.
+                        const wantRepeatBytes = 6
+                        const repeatMask = ((1 << (wantRepeatBytes * 8)) - 1) << (8 * checkRep)
+                        if false && repeat > 0 && cv&repeatMask == load64(src, s-repeat)&repeatMask {
+                                base := s + checkRep
+                                // Extend back
+                                for i := base - repeat; base > nextEmit && i > 0 && src[i-1] == src[base-1]; {
+                                        i--
+                                        base--
+                                }
+                                d += emitLiteral(dst[d:], src[nextEmit:base])
+
+                                // Extend forward
+                                candidate := s - repeat + wantRepeatBytes + checkRep
+                                s += wantRepeatBytes + checkRep
+                                for s < len(src) {
+                                        if len(src)-s < 8 {
+                                                if src[s] == src[candidate] {
+                                                        s++
+                                                        candidate++
+                                                        continue
+                                                }
+                                                break
+                                        }
+                                        if diff := load64(src, s) ^ load64(src, candidate); diff != 0 {
+                                                s += bits.TrailingZeros64(diff) >> 3
+                                                break
+                                        }
+                                        s += 8
+                                        candidate += 8
+                                }
+                                // same as `add := emitCopy(dst[d:], repeat, s-base)` but skips storing offset.
+                                d += emitRepeat(dst[d:], repeat, s-base)
+                                nextEmit = s
+                                if s >= sLimit {
+                                        goto emitRemainder
+                                }
+                                // Index in-between
+                                index0 := base + 1
+                                index1 := s - 2
+
+                                for index0 < index1 {
+                                        cv0 := load64(src, index0)
+                                        cv1 := load64(src, index1)
+                                        lTable[hash7(cv0, lTableBits)] = uint32(index0)
+                                        sTable[hash4(cv0>>8, sTableBits)] = uint32(index0 + 1)
+
+                                        lTable[hash7(cv1, lTableBits)] = uint32(index1)
+                                        sTable[hash4(cv1>>8, sTableBits)] = uint32(index1 + 1)
+                                        index0 += 2
+                                        index1 -= 2
+                                }
+
+                                cv = load64(src, s)
+                                continue
+                        }
+
+                        // Long likely matches 7, so take that.
+                        if uint32(cv) == uint32(valLong) {
+                                break
+                        }
+
+                        // Check our short candidate
+                        if uint32(cv) == uint32(valShort) {
+                                // Try a long candidate at s+1
+                                hashL = hash7(cv>>8, lTableBits)
+                                candidateL = int(lTable[hashL])
+                                lTable[hashL] = uint32(s + 1)
+                                if uint32(cv>>8) == load32(src, candidateL) {
+                                        s++
+                                        break
+                                }
+                                // Use our short candidate.
+                                candidateL = candidateS
+                                break
+                        }
+
+                        cv = load64(src, nextS)
+                        s = nextS
+                }
+
+                // Extend backwards
+                for candidateL > 0 && s > nextEmit && src[candidateL-1] == src[s-1] {
+                        candidateL--
+                        s--
+                }
+
+                // Bail if we exceed the maximum size.
+                if d+(s-nextEmit) > dstLimit {
+                        return 0
+                }
+
+                base := s
+                offset := base - candidateL
+
+                // Extend the 4-byte match as long as possible.
+                s += 4
+                candidateL += 4
+                for s < len(src) {
+                        if len(src)-s < 8 {
+                                if src[s] == src[candidateL] {
+                                        s++
+                                        candidateL++
+                                        continue
+                                }
+                                break
+                        }
+                        if diff := load64(src, s) ^ load64(src, candidateL); diff != 0 {
+                                s += bits.TrailingZeros64(diff) >> 3
+                                break
+                        }
+                        s += 8
+                        candidateL += 8
+                }
+
+                if offset > 65535 && s-base <= 5 && repeat != offset {
+                        // Bail if the match is equal or worse to the encoding.
+                        s = nextS + 1
+                        if s >= sLimit {
+                                goto emitRemainder
+                        }
+                        cv = load64(src, s)
+                        continue
+                }
+
+                d += emitLiteral(dst[d:], src[nextEmit:base])
+                if repeat == offset {
+                        d += emitRepeat(dst[d:], offset, s-base)
+                } else {
+                        d += emitCopy(dst[d:], offset, s-base)
+                        repeat = offset
+                }
+
+                nextEmit = s
+                if s >= sLimit {
+                        goto emitRemainder
+                }
+
+                if d > dstLimit {
+                        // Do we have space for more, if not bail.
+                        return 0
+                }
+
+                // Index short & long
+                index0 := base + 1
+                index1 := s - 2
+
+                cv0 := load64(src, index0)
+                cv1 := load64(src, index1)
+                lTable[hash7(cv0, lTableBits)] = uint32(index0)
+                sTable[hash4(cv0>>8, sTableBits)] = uint32(index0 + 1)
+
+                lTable[hash7(cv1, lTableBits)] = uint32(index1)
+                sTable[hash4(cv1>>8, sTableBits)] = uint32(index1 + 1)
+                index0 += 1
+                index1 -= 1
+                cv = load64(src, s)
+
+                // Index large values sparsely in between.
+                // We do two starting from different offsets for speed.
+                index2 := (index0 + index1 + 1) >> 1
+                for index2 < index1 {
+                        lTable[hash7(load64(src, index0), lTableBits)] = uint32(index0)
+                        lTable[hash7(load64(src, index2), lTableBits)] = uint32(index2)
+                        index0 += 2
+                        index2 += 2
+                }
+        }
+
+emitRemainder:
+        if nextEmit < len(src) {
+                // Bail if we exceed the maximum size.
+                if d+len(src)-nextEmit > dstLimit {
+                        return 0
+                }
+                d += emitLiteral(dst[d:], src[nextEmit:])
+        }
+        return d
+}