hello world in D

Paulo Pinto pjmlp at progtools.org
Sat Jun 1 03:32:19 PDT 2013


Am 31.05.2013 19:21, schrieb Rob T:
> On Friday, 31 May 2013 at 16:52:53 UTC, Jonathan M Davis wrote:
>> On Friday, May 31, 2013 18:05:16 Rob T wrote:
>>> I've seen this happen with 2.062, if you take out -noboundscheck
>>> it may reduce the size significantly and compile a lot faster.
>>> Makes no sense.
>>
>> My first guess would be that more ends up being inlined with
>> -noboundscheck due
>> to the differences in the code that's being generated, but I really
>> don't knw.
>>
>> - Jonathan M Davis
>
> I discovered this last night while playing around with the raytrace
> performance issue a few threads back. I noticed that Derelict was being
> built without -noboundscheck so I put the flag in to see what if
> anything would happen.
>
> The difference is from a few kilobytes per lib to a few megabytes per
> lib, so it's a drastic increase and it takes a lot more time to build.
> This may be something that should be investigated further.
>
> --rt

dmd is not alone in this regard.

There is a presentation from Chandler Carruth on the last LLVM 
conference, http://llvm.org/devmtg/2013-04/ where he rants about that in 
C++ code.

Basically there are some use cases in C++ where the optimizer currently 
does the wrong thing and the generated code increases exponentially.

--
Paulo


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