85 lines
2.2 KiB
Smalltalk
85 lines
2.2 KiB
Smalltalk
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"
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As I traverste the graph, I find equivalent nodes and I merge the equivalent nodes under the single one.
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This saves compiler time, number of instance variables needed and makes compiled class more compact.
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I am using `node:equals:` because of performance (I do cache allNodes) which took too much time to constantly compute...
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"
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Class {
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#name : 'PPCMergingVisitor',
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#superclass : 'PPCRewritingVisitor',
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#instVars : [
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'nodeSet',
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'childrenCache'
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],
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#category : 'PetitCompiler-Visitors'
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}
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{ #category : 'children cache' }
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PPCMergingVisitor >> cachedChildren: node [
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^ childrenCache at: node ifAbsentPut: [
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node dfsOrder
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]
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]
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{ #category : 'node comparison' }
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PPCMergingVisitor >> equivalentNode: node [
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self halt: 'not used?'.
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^ nodeSet detect: [ :e | self node: e equals: node ]
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]
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{ #category : 'node comparison' }
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PPCMergingVisitor >> equivalentNode: node ifNone: block [
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^ nodeSet detect: [ :e | self node: e equals: node ] ifNone: block
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]
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{ #category : 'node comparison' }
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PPCMergingVisitor >> hasEquivalentNode: node [
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^ nodeSet contains: [ :e | self node: e equals: node ]
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]
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{ #category : 'initialization' }
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PPCMergingVisitor >> initialize [
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super initialize.
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"Though this is IdentitySet, I do assert node:equals: befoere inserting node into the set"
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nodeSet := IdentitySet new.
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childrenCache := IdentityDictionary new.
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]
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{ #category : 'node comparison' }
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PPCMergingVisitor >> node: node equals: anotherNode [
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| children anotherChildren |
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(node equals: anotherNode) ifFalse: [ ^ false ].
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children := self cachedChildren: node.
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anotherChildren := self cachedChildren: anotherNode.
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(children size = anotherChildren size) ifFalse: [ ^ false ].
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children with: anotherChildren do: [ :n1 :n2 |
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(n1 equals: n2) ifFalse: [ ^ false ]
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].
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^ true
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]
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{ #category : 'node comparison' }
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PPCMergingVisitor >> store: node [
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self assert: (self hasEquivalentNode: node) not.
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nodeSet add: node
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]
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{ #category : 'traversing' }
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PPCMergingVisitor >> visitNode: node [
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| equivalent |
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"merge the conntent of the node"
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super visitNode: node.
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(equivalent := self equivalentNode: node ifNone: nil ) isNil ifFalse: [
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self cache: node value: equivalent.
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^ equivalent
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].
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self store: node.
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^ node
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]
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