Computed gotos on Reddit

[Walter Bright]

On 7/25/2012 4:26 AM, Dmitry Olshansky wrote:
> On 25-Jul-12 15:14, Don Clugston wrote:
>> On 25/07/12 12:11, Walter Bright wrote:
>>> On 7/25/2012 12:51 AM, Don Clugston wrote:
>>>> so that there is no lookup table, just a multiply.
>>>
>>> Rethinking your idea a bit...
>>>
>>> Suppose the switch jump_address[] array was really an array of hardcoded
>>> jmp instructions, 5 bytes each:
>>>
>>>    jmp_table:
>>>      jmp Lcase1;
>>>      jmp Lcase2;
>>>      jmp Lcase3;
>>>      ...
>>>
>>> and then the switch(EBX) would be:
>>>
>>>      lea EAX,jmp_table[EBX][EBX*4]
>>>      jmp EAX
>>>
>>> is that kick-ass or what?
>>>
>>> (There'd be some additional complication for PIC code.)
>>
>> Very nice. The jumps in the jump table take effectively zero cycles.
>> That looks quite doable.
>
> Looks neat. I'd more then willing to test how it affects my tiny VM in std.regex.
>

Is it possible you could code it up and test it using inline asm?