Please review Compiler-nice.260 in the inbox because emitying code of a
special assigment for effect seems to push twice the binding and pop only
once. (If you run Decompiler tests you can see it)


2013/4/3 <commits at source.squeak.org>

> Eliot Miranda uploaded a new version of Compiler to project The Trunk:
> http://source.squeak.org/trunk/Compiler-eem.258.mcz
>
> ==================== Summary ====================
>
> Name: Compiler-eem.258
> Author: eem
> Time: 3 April 2013, 12:59:36.409 pm
> UUID: 7721a43f-63e6-4524-bb6d-48eddc955654
> Ancestors: Compiler-eem.257
>
> Fix store of special bindings.  Exsting code dropped the
> value assigned from the stack, so v := binding := expr would
> leave v holding binding, not expr.  New code generates
>         push expr
>         push binding
>         duplicate expr (by pushTemp: of expr's stack index)
>         send value:
>         pop
>
> =============== Diff against Compiler-eem.257 ===============
>
> Item was changed:
>   ----- Method: AssignmentNode>>emitCodeForEffect:encoder: (in category
> 'code generation') -----
>   emitCodeForEffect: stack encoder: encoder
>
> +       variable emitCodeForLoad: stack forValue: false encoder: encoder.
> -       variable emitCodeForLoad: stack encoder: encoder.
>         value emitCodeForValue: stack encoder: encoder.
>         pc := encoder methodStreamPosition + 1. "debug pc is first byte of
> the store, i.e. the next byte".
>         variable emitCodeForStorePop: stack encoder: encoder!
>
> Item was changed:
>   ----- Method: AssignmentNode>>emitCodeForValue:encoder: (in category
> 'code generation') -----
>   emitCodeForValue: stack encoder: encoder
>
> +       variable emitCodeForLoad: stack forValue: true encoder: encoder.
> -       variable emitCodeForLoad: stack encoder: encoder.
>         value emitCodeForValue: stack encoder: encoder.
>         pc := encoder methodStreamPosition + 1. "debug pc is first byte of
> the store, i.e. the next byte".
>         variable emitCodeForStore: stack encoder: encoder!
>
> Item was changed:
>   ----- Method: AssignmentNode>>sizeCodeForEffect: (in category 'code
> generation') -----
>   sizeCodeForEffect: encoder
>
> +       ^(variable sizeCodeForLoad: encoder forValue: false)
> -       ^(variable sizeCodeForLoad: encoder)
>         + (value sizeCodeForValue: encoder)
>         + (variable sizeCodeForStorePop: encoder)!
>
> Item was changed:
>   ----- Method: AssignmentNode>>sizeCodeForValue: (in category 'code
> generation') -----
>   sizeCodeForValue: encoder
>
> +       ^(variable sizeCodeForLoad: encoder forValue: true)
> -       ^(variable sizeCodeForLoad: encoder)
>         + (value sizeCodeForValue: encoder)
>         + (variable sizeCodeForStore: encoder)!
>
> Item was added:
> + ----- Method: BytecodeEncoder>>sizePushTempLong: (in category 'opcode
> sizing') -----
> + sizePushTempLong: tempIndex
> +       ^self sizeOpcodeSelector: #genPushTempLong: withArguments:
> {tempIndex}!
>
> Item was added:
> + ----- Method: EncoderForV3>>genPushTempLong: (in category 'bytecode
> generation') -----
> + genPushTempLong: tempIndex
> +       "See BlueBook page 596"
> +       (tempIndex >= 0 and: [tempIndex < 64]) ifTrue:
> +               ["128   10000000 jjkkkkkk       Push (Receiver Variable,
> Temporary Location, Literal Constant, Literal Variable) [jj] #kkkkkk"
> +                stream
> +                       nextPut: 128;
> +                       nextPut: 64 + tempIndex.
> +                ^self].
> +       ^self outOfRangeError: 'index' index: tempIndex range: 0 to: 63!
>
> Item was removed:
> - ----- Method: FieldNode>>emitCodeForLoad:encoder: (in category 'code
> generation') -----
> - emitCodeForLoad: stack encoder: encoder
> -       rcvrNode emitCodeForValue: stack encoder: encoder.
> -       fieldDef accessKey ifNotNil:[
> -               super emitCodeForValue: stack encoder: encoder.
> -       ].!
>
> Item was added:
> + ----- Method: FieldNode>>emitCodeForLoad:forValue:encoder: (in category
> 'code generation') -----
> + emitCodeForLoad: stack forValue: forValue encoder: encoder
> +       rcvrNode emitCodeForValue: stack encoder: encoder.
> +       fieldDef accessKey ifNotNil:
> +               [super emitCodeForValue: stack encoder: encoder]!
>
> Item was removed:
> - ----- Method: LeafNode>>emitCodeForLoad:encoder: (in category 'code
> generation') -----
> - emitCodeForLoad: stack encoder: encoder
> -       "Default is to do nothing.
> -        Subclasses may need to override."!
>
> Item was added:
> + ----- Method: LeafNode>>emitCodeForLoad:forValue:encoder: (in category
> 'code generation') -----
> + emitCodeForLoad: stack forValue: forValue encoder: encoder
> +       "Default is to do nothing.
> +        Subclasses may need to override."!
>
> Item was removed:
> - ----- Method: LeafNode>>sizeCodeForLoad: (in category 'code generation')
> -----
> - sizeCodeForLoad: encoder
> -       "Default is to do nothing.
> -        Subclasses may need to override."
> -       ^0!
>
> Item was added:
> + ----- Method: LeafNode>>sizeCodeForLoad:forValue: (in category 'code
> generation') -----
> + sizeCodeForLoad: encoder forValue: forValue
> +       "Default is to do nothing.
> +        Subclasses may need to override."
> +       ^0!
>
> Item was removed:
> - ----- Method: LiteralVariableNode>>emitCodeForLoad:encoder: (in category
> 'code generation') -----
> - emitCodeForLoad: stack encoder: encoder
> -       writeNode ifNotNil:
> -               [encoder genPushLiteral: index.
> -                stack push: 1]!
>
> Item was added:
> + ----- Method: LiteralVariableNode>>emitCodeForLoad:forValue:encoder: (in
> category 'code generation') -----
> + emitCodeForLoad: stack forValue: forValue encoder: encoder
> +       "If a normal literal variable (not sending value:), do nothing.
> +        If for value (e.g. v := Binding := expr) do nothing; the work
> will be done in emitCodeForStore:encoder:.
> +        If not for value then indeed load.  The rest of the work will be
> done in  emitCodeForStorePop:encoder:."
> +       (writeNode isNil or: [forValue]) ifTrue: [^self].
> +       encoder genPushLiteral: index.
> +       stack push: 1!
>
> Item was changed:
>   ----- Method: LiteralVariableNode>>emitCodeForStore:encoder: (in
> category 'code generation') -----
>   emitCodeForStore: stack encoder: encoder
> +       | exprOffset |
>         writeNode ifNil: [^encoder genStoreLiteralVar: index].
> +       "On entry the stack has only the expression.  Push the binding,
> +        duplicate the expression, send #value: and pop."
> +       exprOffset := stack position - 1.
> +       encoder genPushLiteral: index.
> +       stack push: 1.
> +       encoder genPushTempLong: exprOffset.
> +       stack push: 1.
> -       "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
> -       or use e.g. valueForStore:"
> -       self flag: #bogus.
>         writeNode
>                 emitCode: stack
>                 args: 1
>                 encoder: encoder
> +               super: false.
> +       stack pop: 1.
> +       encoder genPop!
> -               super: false!
>
> Item was removed:
> - ----- Method: LiteralVariableNode>>sizeCodeForLoad: (in category 'code
> generation') -----
> - sizeCodeForLoad: encoder
> -       self reserve: encoder.
> -       ^(key isVariableBinding and: [key isSpecialWriteBinding])
> -               ifTrue: [encoder sizePushLiteral: index]
> -               ifFalse: [0]!
>
> Item was added:
> + ----- Method: LiteralVariableNode>>sizeCodeForLoad:forValue: (in
> category 'code generation') -----
> + sizeCodeForLoad: encoder forValue: forValue
> +       self reserve: encoder.
> +       ^(key isVariableBinding and: [key isSpecialWriteBinding and:
> [forValue not]])
> +               ifTrue: [encoder sizePushLiteral: index]
> +               ifFalse: [0]!
>
> 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:.
> +       "On entry the stack has only the expression.  Push the binding,
> +        duplicate the expression, send #value: and pop."
> +       ^(encoder sizePushLiteral: index)
> +         + (encoder sizePushTempLong: 0) "we don't know yet, hence long,
> sigh..."
> +         + (writeNode sizeCode: encoder args: 1 super: false)
> +         + encoder sizePop!
> -       ^writeNode sizeCode: encoder args: 1 super: false!
>
> Item was removed:
> - ----- Method: TempVariableNode>>emitCodeForLoad:encoder: (in category
> 'code generation') -----
> - emitCodeForLoad: stack encoder: encoder
> -       remoteNode ~~ nil ifTrue:
> -               [remoteNode emitCodeForLoadFor: self stack: stack encoder:
> encoder]!
>
> Item was added:
> + ----- Method: TempVariableNode>>emitCodeForLoad:forValue:encoder: (in
> category 'code generation') -----
> + emitCodeForLoad: stack forValue: forValue encoder: encoder
> +       remoteNode ~~ nil ifTrue:
> +               [remoteNode emitCodeForLoadFor: self stack: stack encoder:
> encoder]!
>
> Item was removed:
> - ----- Method: TempVariableNode>>sizeCodeForLoad: (in category 'code
> generation') -----
> - sizeCodeForLoad: encoder
> -       ^remoteNode
> -               ifNil: [0]
> -               ifNotNil: [remoteNode sizeCodeForLoadFor: self encoder:
> encoder]!
>
> Item was added:
> + ----- Method: TempVariableNode>>sizeCodeForLoad:forValue: (in category
> 'code generation') -----
> + sizeCodeForLoad: encoder forValue: forValue
> +       ^remoteNode
> +               ifNil: [0]
> +               ifNotNil: [remoteNode sizeCodeForLoadFor: self encoder:
> encoder]!
>
> Item was removed:
> - ----- Method: VariableNode>>emitCodeForLoad:encoder: (in category 'code
> generation') -----
> - emitCodeForLoad: stack encoder: encoder
> -       "Do nothing"!
>
> Item was added:
> + ----- Method: VariableNode>>emitCodeForLoad:forValue:encoder: (in
> category 'code generation') -----
> + emitCodeForLoad: stack forValue: forValue encoder: encoder
> +       "Do nothing"!
>
>
>
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