Eliot Miranda uploaded a new version of Compiler to project The Trunk:
http://source.squeak.org/trunk/Compiler-eem.370.mcz

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

Name: Compiler-eem.370
Author: eem
Time: 11 January 2018, 8:41:19.10862 am
UUID: 277f856e-2abf-452c-a5e0-84d00819a04d
Ancestors: Compiler-eem.369

Move CompiledMethod>>startpcsToBlockExtents and its support machinery to Compiler; it is used both by the Decompiler and the Debugger and so belongs in Compiler, not in Tools.

=============== Diff against Compiler-eem.369 ===============

Item was changed:
  InstructionClient subclass: #BlockLocalTempCounter
  	instanceVariableNames: 'stackPointer scanner blockEnd joinOffsets'
  	classVariableNames: ''
  	poolDictionaries: ''
  	category: 'Compiler-Support'!
  
+ !BlockLocalTempCounter commentStamp: 'eem 1/11/2018 08:30' prior: 0!
+ I am a support class for the decompiler that is used to find the number of local temps in a block by finding out what the stack offset is at the end of a block.  I am necessary because in the EncoderForV3PlusClosures bytecode set the only way to initialize block-local temporaries is with pushConstant: nil bytecodes, but such bytecodes are ambiguous with a pushConstant: nil used to pass nil as a parameter or answer it as a result.  By scanning through to the end of the block these can be disambiguated by tracking the stack depth.!
- !BlockLocalTempCounter commentStamp: '<historical>' prior: 0!
- I am a support class for the decompiler that is used to find the number of local temps in a block by finding out what the stack offset is at the end of a block.!

Item was added:
+ InstructionClient subclass: #BlockStartLocator
+ 	instanceVariableNames: ''
+ 	classVariableNames: ''
+ 	poolDictionaries: ''
+ 	category: 'Compiler-Support'!
+ 
+ !BlockStartLocator commentStamp: 'eem 1/11/2018 08:32' prior: 0!
+ A BlockStartLocator is a scanner that locates the block creation bytecodes in a method.  For block creation bytecodes it answers information salient to the kind of block being created, and for all other bytecodes simply answers itself.
+ 
+ Instance Variables
+ !

Item was added:
+ ----- Method: BlockStartLocator>>pushClosureCopyNumCopiedValues:numArgs:blockSize: (in category 'instruction decoding') -----
+ pushClosureCopyNumCopiedValues: numCopied numArgs: numArgs blockSize: blockSize
+ 	"Answer the size of the block"
+ 	^blockSize!

Item was added:
+ ----- Method: BlockStartLocator>>pushFullClosure:numCopied: (in category 'instruction decoding') -----
+ pushFullClosure: aCompiledBlock numCopied: numCopied
+ 	"Answer the block method"
+ 	^aCompiledBlock!

Item was added:
+ ----- Method: CompiledMethod>>blockExtentsInto:from:to:scanner:numberer: (in category '*Compiler-support') -----
+ blockExtentsInto: aDictionary from: initialPC to: endPC scanner: scanner numberer: numbererBlock
+ 	"Support routine for startpcsToBlockExtents"
+ 	| extentStart blockSizeOrLocator |
+ 	extentStart := numbererBlock value.
+ 	[scanner pc <= endPC] whileTrue:
+ 		[blockSizeOrLocator := scanner interpretNextInstructionFor: BlockStartLocator new.
+ 		 blockSizeOrLocator isInteger ifTrue:
+ 			[self
+ 				blockExtentsInto: aDictionary
+ 				from: scanner pc
+ 				to: scanner pc + blockSizeOrLocator - 1
+ 				scanner: scanner
+ 				numberer: numbererBlock]].
+ 	aDictionary at: initialPC put: (extentStart to: numbererBlock value).
+ 	^aDictionary!

Item was added:
+ ----- Method: CompiledMethod>>startpcsToBlockExtents (in category '*Compiler-support') -----
+ startpcsToBlockExtents
+ 	"Answer a Dictionary of startpc to Interval of blockExtent, using the
+ 	 identical numbering scheme described in and orchestrated by
+ 	 BlockNode>>analyseArguments:temporaries:rootNode:.  This is used
+ 	 to find the temp names for any block in a method, as needed by the
+ 	 decompiler and debugger.  By indirecting through the blockExtent
+ 	 instead of using the startpc directly we decouple access to temp
+ 	 names from the exact bytecode; insulating the decompiler and
+ 	 debugger from minor changes in the compiler's output.  If the
+ 	 recompilation doesn't produce exactly the same bytecode at exactly
+ 	 the same offset no matter; the blockExtents will be the same."
+ 	| index |
+ 	index := 0.
+ 	^self
+ 		blockExtentsInto: Dictionary new
+ 		from: self initialPC
+ 		to: self endPC
+ 		scanner: (InstructionStream on: self)
+ 		numberer: [| value | value := index. index := index + 2. value]!