A new version of Kernel was added to project The Inbox:
http://source.squeak.org/inbox/Kernel-ul.664.mcz

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

Name: Kernel-ul.664
Author: ul
Time: 9 January 2012, 2:46:30.214 am
UUID: cc70b7c6-5bbd-4a4e-9bd1-4a22915a61de
Ancestors: Kernel-bf.663

Enhanced pointer tracing:
- handle SmallIntegers correctly (they don't point to any object)
- handle instances of compact classes correctly (they don't point to their class)
- weak references are ignored, because they don't stop the garbage collector in collecting objects
These changes modify the behavior of #pointsTo:, #outboundPointersDo: and #inboundPointersExcluding:.

=============== Diff against Kernel-bf.663 ===============

Item was added:
+ ----- Method: Behavior>>isCompact (in category 'testing') -----
+ isCompact
+ 
+ 	^self indexIfCompact ~= 0!

Item was changed:
  ----- Method: CompiledMethod>>outboundPointersDo: (in category 'tracing') -----
  outboundPointersDo: aBlock
+ 	"Evaluate aBlock for all objects I am causing not to be garbage-collected."
  
+ 	self class isCompact ifFalse: [ aBlock value: self class ].
+ 	1 to: self numLiterals do: [ :i | aBlock value: (self literalAt: i) ]!
- 	| numLiterals |
- 	aBlock value: self class.
- 	numLiterals := self numLiterals.
- 	1 to: numLiterals do: [:i | aBlock value: (self literalAt: i)]!

Item was changed:
  ----- Method: Object>>inboundPointers (in category 'tracing') -----
  inboundPointers
+ 	"Answer a list of all objects in the system that hold a strong reference to me."
- "Answers a collection of all objects in the system that point to myself"
  
  	^ self inboundPointersExcluding: #()!

Item was changed:
  ----- Method: Object>>inboundPointersExcluding: (in category 'tracing') -----
  inboundPointersExcluding: objectsToExclude
+ 	"Answer a list of all objects in the system that hold a strong reference to me, excluding those in the collection of objectsToExclude."
- "Answer a list of all objects in the system that point to me, excluding those in the collection of objectsToExclude. I do my best to avoid creating any temporary objects that point to myself, especially method and block contexts. Adapted from PointerFinder class >> #pointersTo:except:"
  
+ 	| pointers object objectsToAlwaysExclude |
- 	| anObj pointers objectsToAlwaysExclude |
  	Smalltalk garbageCollect.
+ 	pointers := OrderedCollection new.
+ 	"SystemNavigation >> #allObjectsDo: is inlined here with a slight modification: the marker object is pointers. This gives better results, because the value of pointers, it's inner objects and transient method contexts will not be iterated over."
+ 	object := self someObject.
+ 	[ object == pointers ] whileFalse: [
+ 		(object isInMemory and: [ object pointsTo: self ]) ifTrue: [
+ 			pointers add: object ].
+ 		object := object nextObject ].
- 	"big collection shouldn't grow, so it's contents array is always the same"
- 	pointers := OrderedCollection new: 1000.
- 
- 	"#allObjectsDo: and #pointsTo: are expanded inline to keep spurious
- 	 method and block contexts out of the results"
- 	anObj := self someObject.
- 	[0 == anObj] whileFalse: [ "We must use #== here, to avoid leaving the loop when anObj is another number that's equal to 0 (e.g. 0.0)."
- 		anObj isInMemory
- 			ifTrue: [((anObj instVarsInclude: self)
- 				or: [anObj class == self])
- 					ifTrue: [pointers add: anObj]].
- 		anObj := anObj nextObject].
- 
  	objectsToAlwaysExclude := {
- 		pointers collector.
  		thisContext.
  		thisContext sender.
  		thisContext sender sender.
  		objectsToExclude.
  	}.
+ 	^pointers removeAllSuchThat: [ :ea |
- 
- 	^ pointers removeAllSuchThat: [:ea |
  		(objectsToAlwaysExclude identityIncludes: ea)
+ 			or: [objectsToExclude identityIncludes: ea ] ]!
- 			or: [objectsToExclude identityIncludes: ea]]!

Item was changed:
  ----- Method: Object>>outboundPointers (in category 'tracing') -----
  outboundPointers
+ 	"Answers a list of all objects I am causing not to be garbage collected"
- "Answers a list of all objects I am causing not to be garbage-collected"
  
  	| collection |
  	collection := OrderedCollection new.
  	self outboundPointersDo: [:ea | collection add: ea].
  	^ collection!

Item was changed:
  ----- Method: Object>>outboundPointersDo: (in category 'tracing') -----
  outboundPointersDo: aBlock
+ 	"Evaluate aBlock for all objects I am causing not to be garbage-collected."
- "do aBlock for every object I point to, exactly how the garbage collector would. Adapted from PointerFinder >> #followObject:"
  
+ 	self class isCompact ifFalse: [ aBlock value: self class ].
- 	aBlock value: self class.
  	1 to: self class instSize do: [:i | aBlock value: (self instVarAt: i)].
+ 	self class isWeak ifFalse: [
+ 		1 to: self basicSize do: [:i | aBlock value: (self basicAt: i)] ]!
- 	1 to: self basicSize do: [:i | aBlock value: (self basicAt: i)].!

Item was changed:
  ----- Method: ProtoObject>>pointsTo: (in category 'tracing') -----
  pointsTo: anObject
+ 	"Answers true if the garbage collector would fail to collect anObject because I hold a reference to it, or false otherwise"
- "Answers true if I hold a reference to anObject, or false otherwise. Or stated another way:
  
+ 	(self instVarsInclude: anObject)
+ 		ifTrue: [ 
+ 			self class isWeak ifFalse: [ ^true ].
+ 			1 to: self class instSize do: [ :i | 
+ 				(self instVarAt: i) == anObject ifTrue: [ ^true ] ].
+ 			^false ]
+ 		ifFalse: [ ^self class == anObject and: [ self class isCompact not ] ]!
- Answers true if the garbage collector would fail to collect anObject because I hold a reference to it, or false otherwise"
- 
- 	^ (self instVarsInclude: anObject)
- 		or: [self class == anObject]!

Item was added:
+ ----- Method: SmallInteger>>outboundPointersDo: (in category 'tracing') -----
+ outboundPointersDo: aBlock
+ 	"Evaluate aBlock for all objects I am causing not to be garbage-collected."!

Item was added:
+ ----- Method: SmallInteger>>pointsTo: (in category 'tracing') -----
+ pointsTo: anObject
+ 	"Answers true if the garbage collector would fail to collect anObject because I hold a reference to it, or false otherwise"
+ 
+ 	^false!