Flate: Fix/tweak huffman bit estimates

[klauspost]

New blocks where given an advantage since estimates for new blocks did not include extra bits.

Optimize log2 calculation with faster estimate:

Benchmark_tokens_EstimatedBits-32    	  299931	      4062 ns/op	   0.25 MB/s
Benchmark_tokens_EstimatedBits-32    	 2201341	       543 ns/op	   1.84 MB/s

Before/After

file	out	level	insize	outsize	millis	mb/s
gob-stream	gzkp	-2	1911399616	1410346540	6927	263.13
gob-stream	gzkp	1	1911399616	360099905	5708	319.33
gob-stream	gzkp	2	1911399616	346448934	6334	287.77
gob-stream	gzkp	3	1911399616	339896850	8308	219.39
gob-stream	gzkp	4	1911399616	319850581	9092	200.49
gob-stream	gzkp	5	1911399616	310556560	10675	170.75
gob-stream	gzkp	6	1911399616	309710534	12074	150.96
gob-stream	gzkp	7	1911399616	305960448	14837	122.86
gob-stream	gzkp	8	1911399616	300291259	17893	101.88
gob-stream	gzkp	9	1911399616	280306976	31682	57.54
file	out	level	insize	outsize	millis	mb/s
gob-stream	gzkp	-2	1911399616	1410346519	6767	269.35
gob-stream	gzkp	1	1911399616	361916183	5635	323.47
gob-stream	gzkp	2	1911399616	349857310	6256	291.36
gob-stream	gzkp	3	1911399616	341885261	6885	264.74
gob-stream	gzkp	4	1911399616	321792143	7890	231.01
gob-stream	gzkp	5	1911399616	312085491	8911	204.54
gob-stream	gzkp	6	1911399616	311292135	11114	164.01
gob-stream	gzkp	7	1911399616	305960448	14712	123.90
gob-stream	gzkp	8	1911399616	300291259	17781	102.51
gob-stream	gzkp	9	1911399616	280306976	31161	58.50

file	out	level	insize	outsize	millis	mb/s
github-june-2days-2019.json	gzkp	-2	6273951764	4191425185	22107	270.64
github-june-2days-2019.json	gzkp	1	6273951764	1150816630	18647	320.87
github-june-2days-2019.json	gzkp	2	6273951764	1112997952	21263	281.39
github-june-2days-2019.json	gzkp	3	6273951764	1103339187	25701	232.80
github-june-2days-2019.json	gzkp	4	6273951764	997880134	28780	207.89
github-june-2days-2019.json	gzkp	5	6273951764	963159098	34158	175.16
github-june-2days-2019.json	gzkp	6	6273951764	949542385	39269	152.36
github-june-2days-2019.json	gzkp	7	6273951764	934872037	49069	121.94
github-june-2days-2019.json	gzkp	8	6273951764	921116719	57011	104.95
github-june-2days-2019.json	gzkp	9	6273951764	899793019	84347	70.94
file	out	level	insize	outsize	millis	mb/s
github-june-2days-2019.json	gzkp	-2	6273951764	4196148824	21661	276.22
github-june-2days-2019.json	gzkp	1	6273951764	1125991387	18940	315.90
github-june-2days-2019.json	gzkp	2	6273951764	1107583034	21865	273.64
github-june-2days-2019.json	gzkp	3	6273951764	1103676413	23369	256.03
github-june-2days-2019.json	gzkp	4	6273951764	999153827	25717	232.65
github-june-2days-2019.json	gzkp	5	6273951764	964959169	29933	199.89
github-june-2days-2019.json	gzkp	6	6273951764	951460252	35396	169.03
github-june-2days-2019.json	gzkp	7	6273951764	934872037	48143	124.28
github-june-2days-2019.json	gzkp	8	6273951764	921116719	56076	106.70
github-june-2days-2019.json	gzkp	9	6273951764	899793019	83476	71.68

file	out	level	insize	outsize	millis	mb/s
enwik9	gzkp	-2	1000000000	651299040	3615	263.75
enwik9	gzkp	1	1000000000	384456678	6512	146.44
enwik9	gzkp	2	1000000000	372262266	6973	136.76
enwik9	gzkp	3	1000000000	364294282	8140	117.15
enwik9	gzkp	4	1000000000	341904112	9049	105.39
enwik9	gzkp	5	1000000000	338375880	10652	89.52
enwik9	gzkp	6	1000000000	336071599	11201	85.14
enwik9	gzkp	7	1000000000	329248670	18506	51.53
enwik9	gzkp	8	1000000000	326623117	23616	40.38
enwik9	gzkp	9	1000000000	324205510	29803	32.00
file	out	level	insize	outsize	millis	mb/s
enwik9	gzkp	-2	1000000000	652568269	3534	269.85
enwik9	gzkp	1	1000000000	383140821	6523	146.19
enwik9	gzkp	2	1000000000	372365357	7062	135.04
enwik9	gzkp	3	1000000000	364568604	7674	124.26
enwik9	gzkp	4	1000000000	342411924	8418	113.28
enwik9	gzkp	5	1000000000	338866672	9879	96.53
enwik9	gzkp	6	1000000000	336511427	10474	91.05
enwik9	gzkp	7	1000000000	329248670	18497	51.56
enwik9	gzkp	8	1000000000	326623117	24016	39.71
enwik9	gzkp	9	1000000000	324205510	29511	32.32

file	out	level	insize	outsize	millis	mb/s
10gb.tar	gzkp	-2	10065157632	6540870519	30341	316.36
10gb.tar	gzkp	1	10065157632	5280659104	45780	209.67
10gb.tar	gzkp	2	10065157632	5147972222	48354	198.51
10gb.tar	gzkp	3	10065157632	5059091941	54003	177.75
10gb.tar	gzkp	4	10065157632	4947136306	59389	161.63
10gb.tar	gzkp	5	10065157632	4933679787	71788	133.71
10gb.tar	gzkp	6	10065157632	4895606626	76606	125.30
file	out	level	insize	outsize	millis	mb/s
10gb.tar	gzkp	-2	10065157632	6548123344	29288	327.73
10gb.tar	gzkp	1	10065157632	5214106110	45982	208.75
10gb.tar	gzkp	2	10065157632	5120120494	48900	196.29
10gb.tar	gzkp	3	10065157632	5047291855	52904	181.44
10gb.tar	gzkp	4	10065157632	4943352328	55613	172.60
10gb.tar	gzkp	5	10065157632	4931789557	67581	142.03
10gb.tar	gzkp	6	10065157632	4894858258	71080	135.04
10gb.tar	gzkp	7	10065157632	4849130270	204530	46.93

name                        old speed      new speed      delta
EncodeDigitsConstant1e4-12   349MB/s ± 1%   355MB/s ± 0%    ~     (p=0.107 n=3+3)
EncodeDigitsConstant1e5-12   326MB/s ± 0%   333MB/s ± 1%  +2.24%  (p=0.008 n=3+3)
EncodeDigitsConstant1e6-12   368MB/s ± 1%   381MB/s ± 0%  +3.58%  (p=0.008 n=3+3)
EncodeDigitsSpeed1e4-12      132MB/s ± 1%   135MB/s ± 1%  +2.35%  (p=0.024 n=3+3)
EncodeDigitsSpeed1e5-12      103MB/s ± 0%   102MB/s ± 0%    ~     (p=0.276 n=3+3)
EncodeDigitsSpeed1e6-12      103MB/s ± 0%   107MB/s ± 0%  +4.10%  (p=0.001 n=3+3)
EncodeDigitsDefault1e4-12   65.6MB/s ± 0%  66.7MB/s ± 1%    ~     (p=0.060 n=3+3)
EncodeDigitsDefault1e5-12   60.4MB/s ± 1%  61.7MB/s ± 1%  +2.02%  (p=0.018 n=3+3)
EncodeDigitsDefault1e6-12   59.2MB/s ± 0%  60.1MB/s ± 1%    ~     (p=0.103 n=3+3)
EncodeDigitsCompress1e4-12  45.8MB/s ± 0%  45.8MB/s ± 0%    ~     (p=0.552 n=3+3)
EncodeDigitsCompress1e5-12  26.5MB/s ± 1%  26.7MB/s ± 0%    ~     (p=0.354 n=3+3)
EncodeDigitsCompress1e6-12  24.6MB/s ± 1%  24.9MB/s ± 0%  +1.23%  (p=0.041 n=3+3)
EncodeDigitsSL1e4-12        76.4MB/s ± 0%  78.6MB/s ± 0%  +2.83%  (p=0.000 n=3+3)
EncodeDigitsSL1e5-12         112MB/s ± 0%   117MB/s ± 0%  +5.21%  (p=0.001 n=3+3)
EncodeDigitsSL1e6-12         120MB/s ± 0%   126MB/s ± 1%  +5.07%  (p=0.000 n=3+3)
EncodeTwainConstant1e4-12    255MB/s ± 1%   278MB/s ± 0%  +9.29%  (p=0.002 n=3+3)
EncodeTwainConstant1e5-12    289MB/s ± 1%   301MB/s ± 0%  +4.24%  (p=0.014 n=3+3)
EncodeTwainConstant1e6-12    339MB/s ± 1%   347MB/s ± 0%    ~     (p=0.055 n=3+3)
EncodeTwainSpeed1e4-12      98.5MB/s ± 0%  98.8MB/s ± 0%    ~     (p=0.108 n=3+3)
EncodeTwainSpeed1e5-12       104MB/s ± 1%   105MB/s ± 0%    ~     (p=0.241 n=3+3)
EncodeTwainSpeed1e6-12       112MB/s ± 0%   113MB/s ± 0%  +1.03%  (p=0.019 n=3+3)
EncodeTwainDefault1e4-12    65.9MB/s ± 1%  65.3MB/s ± 1%    ~     (p=0.092 n=3+3)
EncodeTwainDefault1e5-12    68.5MB/s ± 0%  68.7MB/s ± 0%    ~     (p=0.114 n=3+3)
EncodeTwainDefault1e6-12    67.1MB/s ± 2%  70.8MB/s ± 3%  +5.46%  (p=0.049 n=3+3)
EncodeTwainCompress1e4-12   37.3MB/s ± 0%  37.5MB/s ± 1%    ~     (p=0.297 n=3+3)
EncodeTwainCompress1e5-12   20.9MB/s ± 1%  20.6MB/s ± 2%    ~     (p=0.197 n=3+3)
EncodeTwainCompress1e6-12   19.0MB/s ± 0%  18.6MB/s ± 1%  -1.90%  (p=0.018 n=3+3)
EncodeTwainSL1e4-12         70.8MB/s ± 0%  69.9MB/s ± 0%  -1.14%  (p=0.012 n=3+3)
EncodeTwainSL1e5-12          111MB/s ± 0%   111MB/s ± 2%    ~     (p=0.635 n=3+3)
EncodeTwainSL1e6-12          120MB/s ± 1%   123MB/s ± 1%  +2.26%  (p=0.037 n=3+3)

Compression size changes pending...