RelationSlot was compiling a reflective write. But we can do better;

- refactor write: to:  so we do most of the stuff in another method
- implement emitStore: to call that method and use bytecodes to acces ivars

This PR was done to speed up Moose which uses RelationSlots a lot.

src/Slot-Examples/RelationSlot.class.st

@@ -71,17 +71,21 @@ RelationSlot >> checkValue: aValue [
 
 { #category : #'code generation' }
 RelationSlot >> emitStore: aMethodBuilder [
-	"copy of #emitStore from Slot as my superclass has overriden it"
+	"This bytecode does the following: 
+		self updateOld: (self read: anObject) new: newValue in: anObject.
+		super write: newValue to: anObject
+	"
 	| tempName |
 	tempName := '0slotTempForStackManipulation'.
 	aMethodBuilder
 		addTemp: tempName;
 		storeTemp: tempName;
 		popTop;
 		pushReceiver;
-		pushLiteralVariable: (AdditionalBinding key: #slot value: self);
+		pushInstVar: index;
 		pushTemp: tempName;
-		send: #writeSlot:value:
+		send: #updateOld:new:in:;
+		storeInstVar: index
 ]
 
 { #category : #testing }

src/Slot-Examples/ToOneRelationSlot.class.st

@@ -13,21 +13,21 @@ ToOneRelationSlot >> isToOneSlot [
 	^true
 ]
 
-{ #category : #'meta-object-protocol' }
-ToOneRelationSlot >> write: newValue to: anObject [
-
-	| oldValue |
+{ #category : #internal }
+ToOneRelationSlot >> updateOld: oldValue new: newValue in: anObject [
 
-	oldValue := self read: anObject.
 	newValue notNil
 		ifTrue: [ self checkValue: newValue ].
-	self hasInverse 
-		ifTrue: [ 
-			oldValue notNil
+	self hasInverse ifFalse:  [^ self ]. 
+	oldValue notNil
 				ifTrue: [ self removeAssociationFrom: anObject to: oldValue ].
-			newValue notNil
-				ifTrue: [ self addAssociationFrom: anObject to: newValue ] ].
-
+	newValue notNil
+				ifTrue: [ self addAssociationFrom: anObject to: newValue ]
+]
+
+{ #category : #'meta-object-protocol' }
+ToOneRelationSlot >> write: newValue to: anObject [
+	self updateOld: (self read: anObject) new: newValue in: anObject.
 	super write: newValue to: anObject
 ]