[Vm-dev] VM Maker: VMMaker.oscog-eem.622.mcz

[commits at source.squeak.org]

Eliot Miranda uploaded a new version of VMMaker to project VM Maker:
http://source.squeak.org/VMMaker/VMMaker.oscog-eem.622.mcz

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

Name: VMMaker.oscog-eem.622
Author: eem
Time: 26 February 2014, 11:53:23.432 am
UUID: 7a33af68-b347-4a24-b960-e8755f7c49f3
Ancestors: VMMaker.oscog-eem.621

Improve spread in Spur's identity hash from 64% to 75%.
Make primitiveSizeInBytesOfInstance accept 2 args in Newspeak for
VMMirror.
Try and fix initialization of ProcessorClass in Cogit.

=============== Diff against VMMaker.oscog-eem.621 ===============

Item was changed:
  ----- Method: Cogit class>>ancilliaryClasses: (in category 'translation') -----
  ancilliaryClasses: options
+ 	ProcessorClass ifNil:
+ 		[Cogit initializeMiscConstants].
- 	ProcessorClass ifNil: [thisContext methodClass theNonMetaClass initialize].
  	^{	CogMethodZone.
  		CogAbstractInstruction.
  		ProcessorClass basicNew abstractInstructionCompilerClass.
  		CogBlockStart.
  		CogBytecodeDescriptor.
  		CogBytecodeFixup.
  		CogInstructionAnnotation.
  		CogPrimitiveDescriptor.
  		CogBlockMethod.
  		CogMethod },
  	((options at: #NewspeakVM ifAbsent: [false])
  		ifTrue: [{NewspeakCogMethod}]
  		ifFalse: [#()])!

Item was changed:
  ----- Method: InterpreterPrimitives>>primitiveSizeInBytesOfInstance (in category 'memory space primitives') -----
  primitiveSizeInBytesOfInstance
+ 	"Answer the byte size of an instance of the receiver.  If num args > 0
+ 	 then the last argument is a variable size and the size answered is the
+ 	 size of an instance of the receiver with that many indexable elements."
  	<option: #SpurObjectMemory>
  	| byteSizeOrErr |
+ 	self cppIf: NewspeakVM
+ 		ifTrue: "Support VMMirror>>byteSizeOfInstanceOf:WithIndexableVariables:"
+ 			[argumentCount > 2 ifTrue:
+ 				[^self primitiveFailFor: PrimErrBadNumArgs]]
+ 		ifFalse:
+ 			[argumentCount > 1 ifTrue:
+ 				[^self primitiveFailFor: PrimErrBadNumArgs]].
+ 	argumentCount >= 1 ifTrue:
- 	argumentCount > 1 ifTrue:
- 		[^self primitiveFailFor: PrimErrBadNumArgs].
- 	argumentCount = 1 ifTrue:
  		[(objectMemory isIntegerObject: self stackTop) ifFalse:
  			[^self primitiveFailFor: PrimErrBadArgument].
  		 byteSizeOrErr := objectMemory
  								byteSizeOfInstanceOf: (self stackValue: 1)
  								withIndexableSlots: (objectMemory integerValueOf: self stackTop).
  		 byteSizeOrErr < 0 ifTrue:
  			[^self primitiveFailFor: byteSizeOrErr negated].
+ 		 ^self pop: argumentCount + 1 thenPushInteger: byteSizeOrErr].
+ 	byteSizeOrErr := objectMemory byteSizeOfInstanceOf: (self stackValue: 0).
- 		 ^self pop: 2 thenPushInteger: byteSizeOrErr].
- 	byteSizeOrErr := objectMemory byteSizeOfInstanceOf: (self stackValue: 1).
  	byteSizeOrErr < 0 ifTrue:
  		[^self primitiveFailFor: byteSizeOrErr negated].
  	self pop: 1 thenPushInteger: byteSizeOrErr!

Item was changed:
  ----- Method: SpurMemoryManager>>newObjectHash (in category 'accessing') -----
  newObjectHash
  	"Use a slight variation on D.H. Lehmer's linear congruential generator from 1951.
  	 See e.g. http://en.wikipedia.org/wiki/Linear_congruential_generator."
+ 	| hash |
+ 	[lastHash := self cCode: [lastHash * 16807] "7 raisedTo: 5"
- 	lastHash := self cCode: [lastHash * 16807] "7 raisedTo: 5"
  					inSmalltalk: [lastHash := lastHash * 16807 bitAnd: 16rFFFFFFFF].
+ 	 hash := lastHash + (lastHash >> 4). "adding the top bits gives much better spread.  See below:"
+ 	 (hash bitAnd: self identityHashHalfWordMask) = 0] whileTrue.
+ 	^hash
- 	self assert: lastHash ~= 0.
- 	^lastHash + (lastHash >> 8) "adding the top bits gives much better spread.  See below:"
  
+ 	"the standard algorithm doesn't vary well in the least significant bits:"
  	"| r s n |
  	r := 1.
  	n := 256 * 256 * 256.
  	s := Set new: n * 2.
  	n timesRepeat:
+ 		[s add: (r bitAnd: n - 1).
- 		[s add: (r + (r bitShift: -8) bitAnd: n - 1).
  		r := r * 16807 bitAnd: 16rFFFFFFFF].
  	{ s size. s size / n asFloat. s includes: 0. r hex }
+ =>	 #(2097152 0.125 false '16r38000001')"
- =>	#(10702109 0.637895405292511 false '16r38000001')"
  
+ 	"this can be improved by adding in shifted upper bits"
  	"| r s n |
  	r := 1.
  	n := 256 * 256 * 256.
  	s := Set new: n * 2.
  	n timesRepeat:
+ 		[s add: (r + (r bitShift: -8) bitAnd: n - 1).
- 		[s add: (r bitAnd: n - 1).
  		r := r * 16807 bitAnd: 16rFFFFFFFF].
  	{ s size. s size / n asFloat. s includes: 0. r hex }
+ =>	#(10702109 0.637895405292511 false '16r38000001')"
+ 
+ 
+ "but which shift is best?  Looks like -4:"
+ "(-2 to: -15 by: -1) do:
+ 	[:shift|
+ 	| r s n |
+ 	r := 1.
+ 	n := 256 * 256 * 256.
+ 	s := Set new: n * 2.
+ 	n timesRepeat:
+ 		[s add: (r + (r bitShift: shift) bitAnd: n - 1).
+ 		r := r * 16807 bitAnd: 16rFFFFFFFF].
+ 	Transcript cr; print: { shift. s size. s size / n asFloat. s includes: 0. r hex }; flush]
+ 
+ #(-2 8388608 0.5 true '16r38000001')
+ #(-3 8388608 0.5 false '16r38000001')
+ #(-4 12582503 0.749975621700287 true '16r38000001')
+ #(-5 11468379 0.6835686564445495 false '16r38000001')
+ #(-6 11013442 0.656452298164368 true '16r38000001')
+ #(-7 10804094 0.643974184989929 true '16r38000001')
+ #(-8 10702109 0.637895405292511 false '16r38000001')
+ #(-9 10703730 0.637992024421692 false '16r38000001')
+ #(-10 7865201 0.468802511692047 false '16r38000001')
+ #(-11 8444092 0.503307104110718 false '16r38000001')
+ #(-12 10703317 0.6379674077034 true '16r38000001')
+ #(-13 10701116 0.637836217880249 true '16r38000001')
+ #(-14 10689443 0.637140452861786 true '16r38000001')
+ #(-15 7853923 0.4681302905082702 true '16r38000001')"!
- =>	 #(2097152 0.125 false '16r38000001')"!