Andreas Raab uploaded a new version of Compiler to project The Trunk:
http://source.squeak.org/trunk/Compiler-tfel.84.mcz

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

Name: Compiler-tfel.84
Author: tfel
Time: 16 September 2009, 12:55:08 pm
UUID: 8e446c0f-0888-4958-9bb0-6b570361c108
Ancestors: Compiler-nice.83

MethodContext>>who is deprecated, and here we only need the methodClass anyway, so replace that

=============== Diff against Compiler-nice.83 ===============

Item was changed:
  ----- Method: Decompiler>>decompileBlock: (in category 'public access') -----
  decompileBlock: aBlock 
  	"Decompile aBlock, returning the result as a BlockNode.  
  	Show temp names from source if available."
  	"Decompiler new decompileBlock: [3 + 4]"
  	| startpc end homeClass blockNode methodNode home source |
  	(home := aBlock home) ifNil: [^ nil].
  	method := home method.
+ 	(homeClass := home methodClass) == #unknown ifTrue: [^ nil].
- 	(homeClass := home who first) == #unknown ifTrue: [^ nil].
  	constructor := self constructorForMethod: aBlock method.
  	method fileIndex ~~ 0 ifTrue: "got any source code?"
  		[source := [method getSourceFromFile]
  						on: Error
  						do: [:ex | ^ nil].
  		 methodNode := [homeClass compilerClass new
  								parse: source
  								in: homeClass
  								notifying: nil]
  							on: (Smalltalk classNamed: 'SyntaxErrorNotification')
  							do: [:ex | ^ nil].
  		 self withTempNames: methodNode schematicTempNamesString].
  	self initSymbols: homeClass.
  	startpc := aBlock startpc.
  	end := aBlock isClosure
  				ifTrue: [(method at: startpc - 2) * 256
  					  + (method at: startpc - 1) + startpc - 1]
  				ifFalse:
  					[(method at: startpc - 2) \\ 16 - 4 * 256
  					+ (method at: startpc - 1) + startpc - 1].
  	stack := OrderedCollection new: method frameSize.
  	caseExits := OrderedCollection new.
  	statements := OrderedCollection new: 20.
  	super
  		method: method
  		pc: (aBlock isClosure ifTrue: [startpc - 4] ifFalse: [startpc - 5]).
  	aBlock isClosure ifTrue:
  		[numLocalTemps := #decompileBlock: "Get pushClosureCopy... to hack fake temps for copied values"].
  	blockNode := self blockTo: end.
  	stack isEmpty ifFalse: [self error: 'stack not empty'].
  	^blockNode statements first!