[Vm-dev] Re: localIP, instructionPointer,
currentBytecode data size
John M McIntosh
johnmci at smalltalkconsulting.com
Tue Mar 2 17:21:39 UTC 2010
On 2010-03-02, at 12:41 AM, Ang BeePeng wrote:
> Is it true that char* in bold explain difference in both version?
> localIP = pointerForOop(instructionPointer); instead of
This moves the global variable instructionPointer OOPS value into localIP and makes it a memory address.
> localIP = pointerForOop(foo->instructionPointer);
This move the element instructionPointer from foo into localIP, and makes it a memory address. On the PowerPC
this form takes one less assembler instruction than referencing a global. On Intel depending on the compiler it may take less
> In the bluebook, for example
> | fieldIndex |
> fieldIndex := self extractBits: 12 to: 15 of: currentBytecode.
> I thought bytecode should be one byte, 8 bits. Why extracting from the
> second byte?
That is implementation. Take a look at
> Ang Beepeng
> View this message in context: http://n4.nabble.com/localIP-instructionPointer-currentBytecode-data-size-tp1574626p1574737.html
> Sent from the Squeak - VM mailing list archive at Nabble.com.
John M. McIntosh <johnmci at smalltalkconsulting.com> Twitter: squeaker68882
Corporate Smalltalk Consulting Ltd. http://www.smalltalkconsulting.com
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