Hi Ryan, On Tue, Nov 18, 2014 at 7:59 PM, Ryan Macnak <rmacnak@gmail.com> wrote:

What about bytecode pc's? These are indexed based on the physical size of the literals. I don't like the idea of debugging pc -> source mappings, pc coverage data, etc needing invalidation after starting an image on a platform with a different word size.

I think this is taken care of. For example, CompiledMethod>>initialPC already consults wordSize. CompiledMethod>>initialPC "Answer the program counter for the receiver's first bytecode." ^ (self numLiterals + 1) * Smalltalk wordSize + 1 and of course the image bootstrap maps pcs already. i.e. Spur32to64BitBootstrap>>fillInPointerObjectWithPC: obj64 from: obj32 | method | self fillInPointerObject: obj64 from: obj32. (heap64 classIndexOf: obj64) = ClassBlockClosureCompactIndex ifTrue: [method := heap32 fetchPointer: MethodIndex ofObject: (heap32 fetchPointer: ClosureOuterContextIndex ofObject: obj32). self incrementPCField: ClosureStartPCIndex ofObject: obj64 for: method]. (heap64 classIndexOf: obj64) = ClassMethodContextCompactIndex ifTrue: [method := heap32 fetchPointer: MethodIndex ofObject: obj32. self incrementPCField: InstructionPointerIndex ofObject: obj64 for: method] Spur32to64BitBootstrap>>incrementPCField: fieldIndex ofObject: obj64 for: method32 | value nLits | value := heap64 fetchPointer: fieldIndex ofObject: obj64. (heap64 isIntegerObject: value) ifTrue: [nLits := heap32 literalCountOf: method32. heap64 storePointerUnchecked: fieldIndex ofObject: obj64 withValue: (heap64 integerObjectOf: nLits + LiteralStart * 4 + (heap64 integerValueOf: value))] ifFalse: [self assert: (reverseMap at: value) = heap32 nilObject] So I'm more looking for issues where the code implicitly assumes 32-bit pointers, such as digitAt: below. On Tue, Nov 18, 2014 at 7:12 PM, Eliot Miranda <eliot.miranda@gmail.com>

wrote:

...

Hi All,

I'm making good progress on 64-bit Spur in the Stack VM simulator. But I've just noticed an image-level issue which could be indicative of lots of 32-bit assumptions baked into the Squeal/Pharo/Newspeak systems.

SmallInteger>>digitAt: n "Answer the value of an indexable field in the receiver. LargePositiveInteger uses bytes of base two number, and each is a 'digit' base 256. Fail if the argument (the index) is not an Integer or is out of bounds." n>4 ifTrue: [^ 0]. self < 0 ifTrue: [self = SmallInteger minVal ifTrue: ["Can't negate minVal -- treat specially" ^ #(0 0 0 64) at: n]. ^ ((0-self) bitShift: (1-n)*8) bitAnd: 16rFF] ifFalse: [^ (self bitShift: (1-n)*8) bitAnd: 16rFF]

This assumes that SmallInteger is only ever 4 bytes, which is unacceptably wasteful for my approach to 64-bits. In 64-bit Spur, SmallIntegers are 61-bit 2's complement.

I'm raising this example at this point to see if the community might find similar issues and bring them to my attention. -- best, Eliot

-- best, Eliot