Re: [Caml-list] How much optimized is the 'a option type ?

[Markus Mottl <markus.mottl@gmail.com>]

Cross-module inlining (even across compilation units) is already
supported.  I guess what you mean is whether functor arguments are
inlined, which is not yet the case.  There has been some recent work
on this:

  http://www.ocamlpro.com/blog/2013/07/11/inlining-progress-report.html

I'd really love to see something like that in the compiler.

Regards,
Markus

On Fri, Jan 17, 2014 at 10:49 AM, Yotam Barnoy <yotambarnoy@gmail.com> wrote:
> That reminds me -- what is the situation regarding inlining? Is there work
> being done on inlining from other modules? Is heavy inlining being done
> within a module? Would it be possible to annotate with [@@inline] to give
> hints to the compiler at some point?
>
> -Yotam
>
>
> On Fri, Jan 17, 2014 at 9:36 AM, Markus Mottl <markus.mottl@gmail.com>
> wrote:
>>
>> Others have already answered about memory representation, but there is
>> one thing about allocations that many OCaml programmers may not yet be
>> aware of and that can make a noticeable performance difference when
>> used wisely: the OCaml compiler will inspect your code and, under the
>> right conditions, batch together allocations.  E.g. consider this
>> function (references are records, btw.):
>>
>>   let f n =
>>     let x = ref (ref (Some (Some n))) in
>>     [(x, n); (x, n)]
>>
>> One might naively assume that this would lead to seven or so
>> allocations.  But if you inspect the assembly, you'll see only one
>> allocation followed by mere initialization assignments.
>>
>> Such allocation batches can break if, for example, the code calls
>> non-inlined (e.g. recursive or external) functions.  I'm not quite
>> sure about all the rules there, but it's generally trivial to just
>> look at the assembler output to find out what the compiler is doing.
>> In some cases merely calling all functions before any allocations take
>> place can speed up your code.  There are even cases where it may be
>> more efficient to allocate several values in one chunk though only
>> some may be needed depending on branches taken later.
>>
>> Regards,
>> Markus
>>
>> On Fri, Jan 17, 2014 at 2:35 AM, Damien Guichard <alphablock@orange.fr>
>> wrote:
>> > Hello,
>> >
>> > Compared to the code :
>> >
>> > type 'a option = None | Some of 'a
>> >
>> > How do an 'a option value performs ?
>> > Any allocation saved ?
>> > Any indirection removed ?
>> >
>> > Is 'a option just like any sum type ?
>> > Or is 'a option more like an ANSI C pointer type ?
>> >
>> > Regards,
>> >
>> > Damien Guichard
>> >
>> >
>> >
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>>
>>
>> --
>> Markus Mottl        http://www.ocaml.info        markus.mottl@gmail.com
>>
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>



-- 
Markus Mottl        http://www.ocaml.info        markus.mottl@gmail.com