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Subject: Re: [boost] Current Guidance on Compiler Warnings?
From: Gavin Lambert (boost_at_[hidden])
Date: 2018-11-28 23:53:09

On 29/11/2018 07:19, Robert Ramey wrote:
> On 11/28/18 8:34 AM, Daniela Engert wrote:
>> Did you actually bother to think about my proposal? I don't want to take
>> away 'int' (as it is specified in the language). I want an *additional*
>> signed integral type with a sane mathematical definition: an abelian
>> group with modulus. And it should offer a widening multiplication N * N
>> -> 2N in addition to the regular one N * N -> N. The compiler should
>> know about this type and lower it's operations to the corresponding
>> hardware instruction (in most cases a single one).
> Would this be of value only in the (special) case where N is a power of
> 2?  Seems like a very special case to me.  For such a special case, I'd
> expect to be able to insert some inline assembler to do the job as
> opposed to altering the core language.

Here N is referring to the bit size of the type, which is "always"
(barring weird architectures) a power of two.

It is possible to define such a type as a library, using inline assembly
where possible and with a fallback to a less efficient portable
implementation otherwise. Direct compiler support is not required,
though might be nice.

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