DMD is faster than LDC and GDC

John Colvin via Digitalmars-d digitalmars-d at puremagic.com
Thu Nov 12 04:38:47 PST 2015


On Thursday, 12 November 2015 at 12:23:11 UTC, Daniel Kozak wrote:
> V Thu, 12 Nov 2015 12:10:30 +0000
> John Colvin via Digitalmars-d <digitalmars-d at puremagic.com> 
> napsáno:
>
>> On Thursday, 12 November 2015 at 11:59:50 UTC, Daniel Kozak 
>> wrote:
>> > [...]
>> 
>> What versions of these compilers? I suspect the majority 
>> (maybe 80%-ish) of the time is spent allocating memory, so you 
>> might be seeing GC improvements in recent DMD
>
> DMD 2.069
>
> LDC 2.067
>
> GDC 2.065
>
> No it is not cause by memory allocations.
>
> It seems DMD can recognize that fmttable has same result every 
> time, so it does compute it only once.

Ok, then my second hypothesis is that dmd is inferring the pure 
attribute for fmttable because it returns auto (new in 2.069 
IIRC), which enable the above optimisation that you have noted. 
Gdc and ldc (and dmd) can do similar things in their backend, but 
perhaps not here.

Do you have older dmd versions on hand to test?


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