[Vm-dev] VM Maker: VMMaker.oscog-nice.2044.mcz

[commits at source.squeak.org]

Nicolas Cellier uploaded a new version of VMMaker to project VM Maker:
http://source.squeak.org/VMMaker/VMMaker.oscog-nice.2044.mcz

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

Name: VMMaker.oscog-nice.2044
Author: nice
Time: 21 December 2016, 2:43:59.503877 pm
UUID: bf51cf5c-9e79-499e-80e4-2e7d40c359aa
Ancestors: VMMaker.oscog-cb.2043

Correct generateCogMethod/FullBlock which might write one byte too far.

Indeed, (padIfPossibleWithStopsFrom: startAddress to: endAddress) is inclusive (it will write a byte into endAddress).
So it must be called with (self padIfPossibleWithStopsFrom: startAddress to: startAddress + size - 1).

Maybe we were saved by roundUpLength:, or maybe the methodZone further allocated size was not yet used, but we don't have to live that dangerously.

=============== Diff against VMMaker.oscog-cb.2043 ===============

Item was changed:
  ----- Method: Cogit>>generateCogFullBlock (in category 'compile abstract instructions') -----
  generateCogFullBlock
  	"We handle jump sizing simply.  First we make a pass that asks each
  	 instruction to compute its maximum size.  Then we make a pass that
  	 sizes jumps based on the maxmimum sizes.  Then we make a pass
  	 that fixes up jumps.  When fixing up a jump the jump is not allowed to
  	 choose a smaller offset but must stick to the size set in the second pass."
  	<returnTypeC: #'CogMethod *'>
  	<option: #SistaV1BytecodeSet>
  	| codeSize headerSize mapSize totalSize startAddress result method |
  	<var: #method type: #'CogMethod *'>
  	headerSize := self sizeof: CogMethod.
  	methodLabel address: methodZone freeStart.
  	self computeMaximumSizes.
  	methodLabel concretizeAt: methodZone freeStart.
  	codeSize := self generateInstructionsAt: methodLabel address + headerSize.
  	mapSize := self generateMapAt: nil start: methodLabel address + cbNoSwitchEntryOffset.
  .
  	totalSize := methodZone roundUpLength: headerSize + codeSize + mapSize.
  	totalSize > MaxMethodSize ifTrue:
  		[^self cCoerceSimple: MethodTooBig to: #'CogMethod *'].
  	startAddress := methodZone allocate: totalSize.
  	startAddress = 0 ifTrue:
  		[^self cCoerceSimple: InsufficientCodeSpace to: #'CogMethod *'].
  	self assert: startAddress + cbEntryOffset = fullBlockEntry address.
  	self assert: startAddress + cbNoSwitchEntryOffset = fullBlockNoContextSwitchEntry address.
  	result := self outputInstructionsAt: startAddress + headerSize.
  	self assert: startAddress + headerSize + codeSize = result.
+ 	backEnd padIfPossibleWithStopsFrom: result to: startAddress + totalSize - mapSize - 1.
- 	backEnd padIfPossibleWithStopsFrom: result to: startAddress + totalSize - mapSize.
  	self generateMapAt: startAddress + totalSize - 1 start: startAddress + cbNoSwitchEntryOffset.
  	self flag: #TOCHECK. "It's not clear we want the same header than regular methods. 
  	It could be of the same size, but maybe the cmType could be different and the selector could be ignored." 
  	method := self fillInMethodHeader: (self cCoerceSimple: startAddress to: #'CogMethod *')
  					size: totalSize
  					selector: objectMemory nilObject.
  	method cpicHasMNUCaseOrCMIsFullBlock: true.
  	postCompileHook ifNotNil:
  		[self perform: postCompileHook with: method.
  		 postCompileHook := nil].
  	^method!

Item was changed:
  ----- Method: Cogit>>generateCogMethod: (in category 'generate machine code') -----
  generateCogMethod: selector
  	"We handle jump sizing simply.  First we make a pass that asks each
  	 instruction to compute its maximum size.  Then we make a pass that
  	 sizes jumps based on the maxmimum sizes.  Then we make a pass
  	 that fixes up jumps.  When fixing up a jump the jump is not allowed to
  	 choose a smaller offset but must stick to the size set in the second pass."
  	<returnTypeC: #'CogMethod *'>
  	| codeSize headerSize mapSize totalSize startAddress result method |
  	<var: #method type: #'CogMethod *'>
  	headerSize := self sizeof: CogMethod.
  	methodLabel address: methodZone freeStart.
  	self computeMaximumSizes.
  	methodLabel concretizeAt: methodZone freeStart.
  	codeSize := self generateInstructionsAt: methodLabel address + headerSize.
  	mapSize := self generateMapAt: nil start: methodLabel address + cmNoCheckEntryOffset.
  	totalSize := methodZone roundUpLength: headerSize + codeSize + mapSize.
  	totalSize > MaxMethodSize ifTrue:
  		[^self cCoerceSimple: MethodTooBig to: #'CogMethod *'].
  	startAddress := methodZone allocate: totalSize.
  	startAddress = 0 ifTrue:
  		[^self cCoerceSimple: InsufficientCodeSpace to: #'CogMethod *'].
  	self assert: startAddress + cmEntryOffset = entry address.
  	self assert: startAddress + cmNoCheckEntryOffset = noCheckEntry address.
  	result := self outputInstructionsAt: startAddress + headerSize.
  	self assert: startAddress + headerSize + codeSize = result.
+ 	backEnd padIfPossibleWithStopsFrom: result to: startAddress + totalSize - mapSize - 1.
- 	backEnd padIfPossibleWithStopsFrom: result to: startAddress + totalSize - mapSize.
  	self generateMapAt: startAddress + totalSize - 1 start: startAddress + cmNoCheckEntryOffset.
  	self fillInBlockHeadersAt: startAddress.
  	method := self fillInMethodHeader: (self cCoerceSimple: startAddress to: #'CogMethod *')
  					size: totalSize
  					selector: selector.
  	postCompileHook ifNotNil:
  		[self perform: postCompileHook with: method.
  		 postCompileHook := nil].
  	^method!