[Vm-dev] VM Maker: VMMaker.oscog-nice.2723.mcz
Levente Uzonyi
leves at caesar.elte.hu
Tue Mar 10 20:55:10 UTC 2020
Hi Nicolas,
Thanks for the fix. It works.
I wonder why is it necessary to cast to usqInt. Is it just to ensure
unsignedness?
Levente
On Mon, 9 Mar 2020, commits at source.squeak.org wrote:
>
> Nicolas Cellier uploaded a new version of VMMaker to project VM Maker:
> http://source.squeak.org/VMMaker/VMMaker.oscog-nice.2723.mcz
>
> ==================== Summary ====================
>
> Name: VMMaker.oscog-nice.2723
> Author: nice
> Time: 10 March 2020, 12:26:31.04183 am
> UUID: c1319382-406c-43a7-9f55-2b48c4007d80
> Ancestors: VMMaker.oscog-eem.2722
>
> Fix the right shift: dont convert to usqInt a type longer than usqInt
>
> =============== Diff against VMMaker.oscog-eem.2722 ===============
>
> Item was changed:
> ----- Method: CCodeGenerator>>generateBitShift:on:indent: (in category 'C translation') -----
> generateBitShift: msgNode on: aStream indent: level
> "Generate the C code for this message onto the given stream."
>
> + | arg shift rightShift |
> + (self isConstantNode: (arg := msgNode args first) valueInto: [:shiftValue| shift := shiftValue])
> - | arg rcvr shift |
> - arg := msgNode args first.
> - rcvr := msgNode receiver.
> - (self isConstantNode: arg valueInto: [:shiftValue| shift := shiftValue])
> ifTrue: "bit shift amount is a constant"
> + [aStream nextPut: $(.
> - [aStream nextPutAll: '((usqInt) '.
> - self emitCExpression: rcvr on: aStream.
> shift < 0
> + ifTrue:
> + [rightShift := TSendNode new
> + setSelector: #>>
> + receiver: msgNode receiver
> + arguments: {TConstantNode new setValue: shift negated}.
> + self generateShiftRight: rightShift on: aStream indent: level]
> + ifFalse: [self generateShiftLeft: msgNode on: aStream indent: level].
> - ifTrue: [aStream nextPutAll: ' >> '; print: shift negated]
> - ifFalse: [aStream nextPutAll: ' << '; print: shift].
> aStream nextPut: $)]
> ifFalse: "bit shift amount is an expression"
> + [rightShift := TSendNode new
> + setSelector: #>>
> + receiver: msgNode receiver
> + arguments: {TSendNode new
> + setSelector: #negated
> + receiver: arg
> + arguments: #()}.
> + aStream nextPutAll: '(('.
> + self emitCExpression: arg on: aStream.
> + aStream nextPutAll: ' < 0) ? ('.
> + self generateShiftRight: rightShift on: aStream indent: level.
> + aStream nextPutAll: ') : ('.
> + self generateShiftLeft: msgNode on: aStream indent: level.
> - [aStream nextPutAll: '(('.
> - self emitCExpression: arg on: aStream indent: level.
> - aStream nextPutAll: ' < 0) ? ((usqInt) '.
> - self emitCExpression: rcvr on: aStream indent: level.
> - aStream nextPutAll: ' >> -'.
> - self emitCExpression: arg on: aStream indent: level.
> - aStream nextPutAll: ') : ((usqInt) '.
> - self emitCExpression: rcvr on: aStream indent: level.
> - aStream nextPutAll: ' << '.
> - self emitCExpression: arg on: aStream indent: level.
> aStream nextPutAll: '))']!
>
> Item was changed:
> ----- Method: CCodeGenerator>>generateShiftRight:on:indent: (in category 'C translation') -----
> generateShiftRight: msgNode on: aStream indent: level
> + "Generate the C code for this message onto the given stream.
> + Note that this generates a Logical Shift (unsigned), not an Arithmetic Shift (signed)."
> - "Generate the C code for this message onto the given stream."
>
> + | type typeIsUnsigned mustCastToUnsigned unsignedType |
> + type := self typeFor: msgNode receiver in: currentMethod.
> + typeIsUnsigned := type first = $u.
> + mustCastToUnsigned := typeIsUnsigned not or:
> + ["cast to usqInt if the int is shorter: we want to avoid UB related to a shift exceeeding bit width"
> + (self sizeOfIntegralCType: type) < (self sizeOfIntegralCType: #usqInt)].
> + "If not unsigned cast it to unsigned."
> + mustCastToUnsigned
> - | type |
> - "If the variable is a 64-bit type then don't cast it to usqInt (typically a 32-bit type)"
> - (self is64BitIntegralVariable: msgNode receiver typeInto: [:t| type := t])
> ifTrue:
> + ["If the variable is a 64-bit type then don't cast it to usqInt (typically a 32-bit type)"
> + unsignedType := (self sizeOfIntegralCType: type) < (self sizeOfIntegralCType: #usqLong)
> + ifTrue: [#usqInt]
> + ifFalse: [self unsignedTypeForIntegralType: type].
> + aStream nextPutAll: '(('; nextPutAll: unsignedType; nextPutAll: ')('.
> - ["If not unsigned cast it to unsigned."
> - type first ~= $u ifTrue:
> - [aStream nextPutAll: '((unsigned '; nextPutAll: type; nextPut: $)].
> self emitCExpression: msgNode receiver on: aStream indent: level.
> + aStream nextPutAll: '))']
> - type first ~= $u ifTrue:
> - [aStream nextPut: $)]]
> ifFalse:
> + [aStream nextPutAll: '('.
> - [aStream nextPutAll: '((usqInt) '.
> self emitCExpression: msgNode receiver on: aStream indent: level.
> aStream nextPut: $)].
> aStream nextPutAll: ' >> '.
> self emitCExpression: msgNode args first on: aStream indent: level!
>
> Item was changed:
> ----- Method: CCodeGenerator>>generateSignedBitShift:on:indent: (in category 'C translation') -----
> generateSignedBitShift: msgNode on: aStream indent: level
> "Generate the C code for this message onto the given stream."
>
> + | arg shift rightShift |
> - | cast type arg shift |
> - "since ``signed'' is a synonym for ``signed int'' do not cast 64-bit values to signed if at all possible."
> - cast := (self is64BitIntegralVariable: msgNode receiver typeInto: [:t| type := t])
> - ifTrue: ['(', (type first = $u ifTrue: [type allButFirst: (type second = $n ifTrue: [2] ifFalse: [1])] ifFalse: [type]), ')']
> - ifFalse: ['(signed)'].
> (self isConstantNode: (arg := msgNode args first) valueInto: [:shiftValue| shift := shiftValue])
> ifTrue: "bit shift amount is a constant"
> + [aStream nextPut: $(.
> - [aStream nextPut: $(; nextPutAll: cast.
> - self emitCExpression: msgNode receiver on: aStream.
> shift < 0
> + ifTrue:
> + [rightShift := TSendNode new
> + setSelector: #>>
> + receiver: msgNode receiver
> + arguments: {TConstantNode new setValue: shift negated}.
> + self generateSignedShiftRight: rightShift on: aStream indent: level]
> + ifFalse: [self generateShiftLeft: msgNode on: aStream indent: level].
> - ifTrue: [aStream nextPutAll: ' >> '; print: shift negated]
> - ifFalse: [aStream nextPutAll: ' << '; print: shift].
> aStream nextPut: $)]
> ifFalse: "bit shift amount is an expression"
> + [rightShift := TSendNode new
> + setSelector: #>>
> + receiver: msgNode receiver
> + arguments: {TSendNode new
> + setSelector: #negated
> + receiver: arg
> + arguments: #()}.
> + aStream nextPutAll: '(('.
> - [aStream nextPutAll: '(('.
> self emitCExpression: arg on: aStream.
> + aStream nextPutAll: ' < 0) ? ('.
> + self generateSignedShiftRight: rightShift on: aStream indent: level.
> + aStream nextPutAll: ') : ('.
> + self generateShiftLeft: msgNode on: aStream indent: level.
> - aStream nextPutAll: ' < 0) ? ('; nextPutAll: cast.
> - self emitCExpression: msgNode receiver on: aStream.
> - aStream nextPutAll: ' >> -'.
> - self emitCExpression: arg on: aStream.
> - aStream nextPutAll: ') : ('; nextPutAll: cast.
> - self emitCExpression: msgNode receiver on: aStream.
> - aStream nextPutAll: ' << '.
> - self emitCExpression: arg on: aStream.
> aStream nextPutAll: '))']!
>
> Item was changed:
> ----- Method: CCodeGenerator>>generateSignedShiftRight:on:indent: (in category 'C translation') -----
> generateSignedShiftRight: msgNode on: aStream indent: level
> "Generate the C code for >>> onto the given stream."
>
> + | type typeIsUnsigned mustCastToSigned signedType |
> + type := self typeFor: msgNode receiver in: currentMethod.
> + typeIsUnsigned := type first = $u.
> + mustCastToSigned := typeIsUnsigned or:
> + ["cast to sqInt if the int is shorter: we want to avoid UB related to a shift exceeeding bit width"
> + (self sizeOfIntegralCType: type) < (self sizeOfIntegralCType: #usqInt)].
> + mustCastToSigned
> - (self is64BitIntegralVariable: msgNode receiver typeInto: [:t|])
> ifTrue:
> + ["If the variable is a 64-bit type then don't cast it to usqInt (typically a 32-bit type)"
> + signedType := (self sizeOfIntegralCType: type) < (self sizeOfIntegralCType: #usqLong)
> + ifTrue: [#usqInt]
> + ifFalse: [self signedTypeForIntegralType: type].
> + aStream nextPutAll: '(('; nextPutAll: signedType; nextPutAll: ')('.
> + self emitCExpression: msgNode receiver on: aStream indent: level.
> + aStream nextPutAll: '))']
> - [aStream nextPutAll: '((sqLong) ']
> ifFalse:
> + [aStream nextPutAll: '('.
> + self emitCExpression: msgNode receiver on: aStream indent: level.
> + aStream nextPut: $)].
> + aStream nextPutAll: ' >> '.
> - [aStream nextPutAll: '((sqInt) '].
> - self emitCExpression: msgNode receiver on: aStream.
> - aStream nextPutAll: ') >> '.
> self emitCExpression: msgNode args first on: aStream!
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