Re: [PATCH] Re: Bignum performance

[Emanuel Berg]

tomas wrote:

>>>> Are we talking 1 word = 2 bytes = 16 bits here, s2c?
>>>>
>>>> If so, the range of fixnums are -32 768 to 32 767
>>>> inclusive, so those are hardly huge numbers.
>>>
>>> Under Arm64, general purpose integer registers are 64 bits
>>> wide. That is also the word size of said machine.
>> 
>> If they are, the range for fixnums is
>> 
>> (list (* -1 (expt 2 (1- 64)))
>>       (1-   (expt 2 (1- 64))) )
>> 
>> (-9223372036854775808 9223372036854775807)
>> 
>> Only after that it gets slower :P
>
> Unless SBCL uses tagged object representation. Unless the
> compiler can prove that some "thing" is going to be an int.
> Unless...

Actually the rules are quite simple. As long as the expected
execution and correct return value is observed and ultimately
achieved by the algorithm, all optimizations are fair.

-- 
underground experts united
https://dataswamp.org/~incal