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Re: [Scheme-reports] fresh empty strings



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On 01/23/2012 07:03 AM, Andy Wingo wrote:
> On Mon 23 Jan 2012 14:27, Alaric Snell-Pym <alaric@x> writes:
> 
>> Short strings might be represented in a single SSE2 vector register or
>> something
> 
> The point of this nit-pick is that this is impossible -- strings of one
> character *cannot* be immediates.
> 
> Regards,

That's just not true.

The size of immediate values varies from implementation to
implementation.  Even allowing a full byte for a typetag,
in an implementation where immediates are  64-bits it's
possible to have immediate strings of up to 7 UTF8 values.

That's very short for a string, but worth it if you're
handling a lot of strings which are one word (in the language
sense).

You don't have to heap-allocate strings until can no longer
prove that you have only one reference to the string.

				Bear


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