Levente Uzonyi uploaded a new version of Kernel to project The Trunk:
http://source.squeak.org/trunk/Kernel-ul.1058.mcz

==================== Summary ====================

Name: Kernel-ul.1058
Author: ul
Time: 10 February 2017, 1:16:53.505258 pm
UUID: 62aa1881-7b99-4ba0-bfa5-a2599f1386a9
Ancestors: Kernel-eem.1057

- extracted BitCountPerByteTable from Integer >> bitCount
- added optimized version of #bitCount to SmallInteger

=============== Diff against Kernel-eem.1057 ===============

Item was changed:
  Number subclass: #Integer
  	instanceVariableNames: ''
+ 	classVariableNames: 'BitCountPerByteTable LowBitPerByteTable'
- 	classVariableNames: 'LowBitPerByteTable'
  	poolDictionaries: ''
  	category: 'Kernel-Numbers'!
  
  !Integer commentStamp: '<historical>' prior: 0!
  I am a common abstract superclass for all Integer implementations. My implementation subclasses are SmallInteger, LargePositiveInteger, and LargeNegativeInteger.
  	
  Integer division consists of:
  	/	exact division, answers a fraction if result is not a whole integer
  	//	answers an Integer, rounded towards negative infinity
  	\\	is modulo rounded towards negative infinity
  	quo: truncated division, rounded towards zero!

Item was changed:
  ----- Method: Integer class>>initialize (in category 'class initialization') -----
  initialize
+ 	"Integer initialize"
+ 	
+ 	self 
+ 		initializeLowBitPerByteTable;
+ 		initializeBitCountPerByteTable!
- 	"Integer initialize"	
- 	self initializeLowBitPerByteTable!

Item was added:
+ ----- Method: Integer class>>initializeBitCountPerByteTable (in category 'class initialization') -----
+ initializeBitCountPerByteTable
+ 	"Initialize BitCountPerByteTable which is a ByteArray that contains the number of set bits (1) of the integers between 0 and 255. It's defined as a class variable so that it can be used from the instance side and subclasses too."
+ 	"Evaluate this expression to form the byte array:
+ 	((0 to: 255)
+ 		collect: [:i | 
+ 			| bitCount n |
+ 			n := i.
+ 			bitCount := 0.
+ 			[n = 0]
+ 				whileFalse:
+ 					[bitCount := bitCount + 1.
+ 					n := n bitAnd: n - 1].
+ 			bitCount]
+ 		as: ByteArray)"
+ 	
+ 	BitCountPerByteTable := #[0 1 1 2 1 2 2 3 1 2 2 3 2 3 3 4 1 2 2 3 2 3 3 4 2 3 3 4 3 4 4 5 1 2 2 3 2 3 3 4 2 3 3 4 3 4 4 5 2 3 3 4 3 4 4 5 3 4 4 5 4 5 5 6 1 2 2 3 2 3 3 4 2 3 3 4 3 4 4 5 2 3 3 4 3 4 4 5 3 4 4 5 4 5 5 6 2 3 3 4 3 4 4 5 3 4 4 5 4 5 5 6 3 4 4 5 4 5 5 6 4 5 5 6 5 6 6 7 1 2 2 3 2 3 3 4 2 3 3 4 3 4 4 5 2 3 3 4 3 4 4 5 3 4 4 5 4 5 5 6 2 3 3 4 3 4 4 5 3 4 4 5 4 5 5 6 3 4 4 5 4 5 5 6 4 5 5 6 5 6 6 7 2 3 3 4 3 4 4 5 3 4 4 5 4 5 5 6 3 4 4 5 4 5 5 6 4 5 5 6 5 6 6 7 3 4 4 5 4 5 5 6 4 5 5 6 5 6 6 7 4 5 5 6 5 6 6 7 5 6 6 7 6 7 7 8]!

Item was changed:
  ----- Method: Integer>>bitCount (in category 'bit manipulation') -----
  bitCount
  	"Count the number of bits set to 1 in self"
  
  	| bitCount |
  	self < 0 ifTrue: [self error: 'Cannot count bits of negative integers'].
  	bitCount := 0.
  	1 to: self digitLength do: [:i |
+ 		bitCount := bitCount + (BitCountPerByteTable at: (self digitAt: i) + 1) ].
- 		bitCount := bitCount + (self digitAt: i) bitCountOfByte].
  	^bitCount!

Item was added:
+ ----- Method: SmallInteger>>bitCount (in category 'bit manipulation') -----
+ bitCount
+ 	"Count the number of bits set to 1 in self. Overridden for performance"
+ 
+ 	| n bitCount |
+ 	self < 0 ifTrue: [self error: 'Cannot count bits of negative integers'].
+ 	bitCount := 0.
+ 	n := self.
+ 	[ n = 0 ] whileFalse: [
+ 		bitCount := bitCount + (BitCountPerByteTable at: (n bitAnd: 16rFF) + 1).
+ 		n := n bitShift: -8 ].
+ 	^bitCount!

Item was changed:
  ----- Method: SmallInteger>>bitCountOfByte (in category 'bit manipulation') -----
  bitCountOfByte
  	"Count the number of bits set to 1 in a byte."
  
+ 	^BitCountPerByteTable at: self + 1!
- 	^#[0 1 1 2 1 2 2 3 1 2 2 3 2 3 3 4 1 2 2 3 2 3 3 4 2 3 3 4 3 4 4 5 1 2 2 3 2 3 3 4 2 3 3 4 3 4 4 5 2 3 3 4 3 4 4 5 3 4 4 5 4 5 5 6 1 2 2 3 2 3 3 4 2 3 3 4 3 4 4 5 2 3 3 4 3 4 4 5 3 4 4 5 4 5 5 6 2 3 3 4 3 4 4 5 3 4 4 5 4 5 5 6 3 4 4 5 4 5 5 6 4 5 5 6 5 6 6 7 1 2 2 3 2 3 3 4 2 3 3 4 3 4 4 5 2 3 3 4 3 4 4 5 3 4 4 5 4 5 5 6 2 3 3 4 3 4 4 5 3 4 4 5 4 5 5 6 3 4 4 5 4 5 5 6 4 5 5 6 5 6 6 7 2 3 3 4 3 4 4 5 3 4 4 5 4 5 5 6 3 4 4 5 4 5 5 6 4 5 5 6 5 6 6 7 3 4 4 5 4 5 5 6 4 5 5 6 5 6 6 7 4 5 5 6 5 6 6 7 5 6 6 7 6 7 7 8] at: self + 1
- 
- 	"Evaluate this expression to form above byte array:
- 	((0 to: 255)
- 		collect: [:i | 
- 			| bitCount n |
- 			n := i.
- 			bitCount := 0.
- 			[n = 0]
- 				whileFalse:
- 					[bitCount := bitCount + 1.
- 					n := n bitAnd: n - 1].
- 			bitCount]
- 		as: ByteArray)"!