[Pkg] The Trunk: Compiler-nice.173.mcz

[commits at source.squeak.org]

Nicolas Cellier uploaded a new version of Compiler to project The Trunk:
http://source.squeak.org/trunk/Compiler-nice.173.mcz

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

Name: Compiler-nice.173
Author: nice
Time: 8 September 2010, 1:36:04.973 am
UUID: f40f6937-a88a-4f85-b0b0-f68b310a1d92
Ancestors: Compiler-eem.172

Compiler fix for http://bugs.squeak.org/view.php?id=7093
Avoid optimizing a to:do: loop that does modify its limit inside the loop. Thanks Eliot!

Note: an alternate solution would be to create a shadow variable, assign it with the limit, and optimize the block.

Note 2: the bug report also has a so far uncorrected Decompiler part and cannot be closed yet.

=============== Diff against Compiler-eem.172 ===============

Item was changed:
  ----- Method: MessageNode>>transformToDo: (in category 'macro transformations') -----
  transformToDo: encoder
  	" var := rcvr. L1: [var <= arg1] Bfp(L2) [block body. var := var + inc] 
  Jmp(L1) L2: "
+ 	| limit increment block initStmt test incStmt limitInit blockVar myRange blockRange limitIsAssignedTo |
- 	| limit increment block initStmt test incStmt limitInit blockVar myRange blockRange |
  	"First check for valid arguments"
  	((arguments last isMemberOf: BlockNode)
  	  and: [arguments last numberOfArguments = 1
  	  and: [arguments last firstArgument isVariableReference "As with debugger remote vars"]]) ifFalse:
  		[^false].
  	arguments size = 3
  		ifTrue: [increment := arguments at: 2.
  				(increment isConstantNumber
+ 				 and: [increment literalValue ~= 0]) ifFalse: [^false]]
- 				 and: [increment literalValue ~= 0]) ifFalse: [^ false]]
  		ifFalse: [increment := encoder encodeLiteral: 1].
+ 	(limit := arguments at: 1) isVariableReference ifTrue:
+ 		[limitIsAssignedTo := false.
+ 		 arguments last nodesDo:
+ 			[:node|
+ 			(node isAssignmentNode and: [node variable = limit]) ifTrue:
+ 				[limitIsAssignedTo := true]].
+ 		 limitIsAssignedTo ifTrue:
+ 			[^false]].
  	arguments size < 3 ifTrue:   "transform to full form"
  		[selector := SelectorNode new key: #to:by:do: code: #macro].
  
  	"Now generate auxiliary structures"
  	myRange := encoder rawSourceRanges at: self ifAbsent: [1 to: 0].
  	block := arguments last.
  	blockRange := encoder rawSourceRanges at: block ifAbsent: [1 to: 0].
  	blockVar := block firstArgument.
  	initStmt := AssignmentNode new variable: blockVar value: receiver.
- 	limit := arguments at: 1.
  	limit isVariableReference | limit isConstantNumber
  		ifTrue: [limitInit := nil]
  		ifFalse:  "Need to store limit in a var"
  			[limit := encoder bindBlockArg: blockVar key, 'LimiT' within: block.
  			 limit scope: -2.  "Already done parsing block; flag so it won't print"
  			 block addArgument: limit.
  			 limitInit := AssignmentNode new
  							variable: limit
  							value: arguments first].
  	test := MessageNode new
  				receiver: blockVar
  				selector: (increment key > 0 ifTrue: [#<=] ifFalse: [#>=])
  				arguments: (Array with: limit)
  				precedence: precedence from: encoder
  				sourceRange: (myRange first to: blockRange first).
  	incStmt := AssignmentNode new
  				variable: blockVar
  				value: (MessageNode new
  							receiver: blockVar selector: #+
  							arguments: (Array with: increment)
  							precedence: precedence from: encoder)
  				from: encoder
  				sourceRange: (myRange last to: myRange last).
  	arguments := (Array with: limit with: increment with: block),
  					(Array with: initStmt with: test with: incStmt with: limitInit).
  	block noteOptimizedIn: self.
  	^true!