Eliot Miranda uploaded a new version of Compiler to project The Trunk:
http://source.squeak.org/trunk/Compiler-eem.168.mcz

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

Name: Compiler-eem.168
Author: eem
Time: 17 August 2010, 5:15:54.534 pm
UUID: 0757e13e-9323-4603-927b-224965d39773
Ancestors: Compiler-eem.166

Merge with Compiler-nice.164.

Fix the case of special write binding.
Reminder: in case of special write binding, we must:
	1) load the VariableBinding
	2) push assigned value
	3) send value:
(see AssignmentNode>>emitCodeForEffect:encoder: )

#sizeCodeForLoad: read inst var writeNode
#sizeCodeForStore: write inst var writeNode
#sizeCodeForLoad: is sent before #sizeCodeForStore:
Therefore writeNode is read before written and the door is open for bugs.

Fortunately, #sizeCodeForStore: redo the job of #sizeCodeForLoad: and reserve space for pushing the VariableBinding on stack.

Unfortunately, it sometimes happens that the sizeCodeFor... is requested twice, the writeNode is then initialized and sizeCodeForLoad: reserve space for pushing VariableBinding a second time leading to a code size discrepancy...

Present fix implement following solution:
1) let sizeCodeForLoad: reserve size for emitCodeForLoad:encoder: operations, but don't trust writeNode isNil for this job.
2) let sizeCodeForStore: reserve size for - and only for - emitCodeForStore:encoder: operations.

=============== Diff against Compiler-eem.166 ===============

Item was changed:
  ----- Method: LiteralVariableNode>>sizeCodeForLoad: (in category 'code generation') -----
  sizeCodeForLoad: encoder
+ 	self reserve: encoder.
+ 	^(key isVariableBinding and: [key isSpecialWriteBinding])
+ 		ifTrue: [encoder sizePushLiteral: index]
+ 		ifFalse: [0]!
- 	^writeNode ifNil: [0] ifNotNil: [encoder sizePushLiteral: index]!

Item was changed:
  ----- Method: LiteralVariableNode>>sizeCodeForStore: (in category 'code generation') -----
  sizeCodeForStore: encoder
  	self reserve: encoder.
  	(key isVariableBinding and: [key isSpecialWriteBinding]) ifFalse:
  		[^encoder sizeStoreLiteralVar: index].
  	code < 0 ifTrue:
  		[self flag: #dubious.
  		 self code: (self code: self index type: LdLitType)].
  	"THIS IS WRONG!!!! THE VALUE IS LOST FROM THE STACK!!!!
  	 The various value: methods on Association ReadOnlyVariableBinding
  	 etc _do not_ return the value assigned; they return the receiver."
  	"Should generate something more like
  		push expr
  		push lit
  		push temp (index of expr)
  		send value:
  		pop"
  	self flag: #bogus.
  	writeNode := encoder encodeSelector: #value:.
+ 	^writeNode sizeCode: encoder args: 1 super: false!
- 	^(encoder sizePushLiteralVar: index)
- 	 + (writeNode sizeCode: encoder args: 1 super: false)!