The Trunk: Compiler-nice.164.mcz

Nicolas Cellier uploaded a new version of Compiler to project The Trunk:
http://source.squeak.org/trunk/Compiler-nice.164.mcz

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

Name: Compiler-nice.164
Author: nice
Time: 17 August 2010, 10:45:20.737 pm
UUID: edf34da9-a326-490b-97f9-2768511b2768
Ancestors: Compiler-eem.163

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.163 ===============

Item was changed:
  ----- Method: LiteralVariableNode>>sizeCodeForLoad: (in category 'code generation (new scheme)') -----
  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 (new scheme)') -----
  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)!