On 2008-12-13 19:07:09 +0100, "Jarrett Billingsley"
<jarrett.billings...@gmail.com> said:
On Sat, Dec 13, 2008 at 12:55 PM, Jason House
<jason.james.ho...@gmail.com> wrote:
Jarrett Billingsley wrote:
I hope bearophile will eventually understand that DMD is not good at
optimizing code, and so comparing its output to GCC's is ultimately
meaningless.
Personally, I appreciate seeing this stuff from bearophile. I use D in
ways where speed really does count. One of my draws to D was that it
was a systems language that could be faster than something like Java.
I also was sick of C++ and its problems, such as code that requires
workarounds for compiler bugs or lack of compiler optimization. It's
really sad to see D requiring the same kind of stuff. For D to become
as mainstream as C++, all of this stuff that bearophile posts must be
fixed.
Walter is the only one who can make DMD faster, and I think his time
is much better spent on designing and maintaining the language. The
reference compiler is just supposed to be _correct_, not necessarily
_fast_. If Walter spent all his time working on making the the DMDFE
optimizer better and making DMD backend produce faster code, he
wouldn't have time to work on the language anymore, and it would be
duplicated effort since GDC and LDC already do it better.
I fully agree, and it is not that DMD is necessarily slow, but does not
perform some kinds of optimizations.
For example for the nested loops it does not float the operations out
of the internal loop to as high up as possible.
I would like for this to be the case (for example my multidimensional
array library would profit from this), but if you really see that in
your code it becomes and issue (looking at profiling) then normally it
is quite easy to rewrite it so that it is fast.
Just looking at very specific benchmarks that test one kind of
optimization can be very misleading.
It is good to have benchmarks and know where the weaknesses of a
compiler are, but for real code the situation is different.
At least for the code that I write, and typical code I have seen DMD is
reasonably competitive.
(this does not mean that it can't and shouldn't be improved ;)
Fawzi
