Lower than C?

[Christopher Wright]

bearophile wrote:
> Jesse Phillips:
> 
> Thank you for your comments.
> 
>> That is to say the less specific something is described the more one can optimize to build for it.<
> 
> But you need a quite more intelligent compiler to do (optimize) it, and to build a more intelligent compiler you need much more work and time. You can see how the Intel compiler optimizes compared to DMD, and the Intel compiler is quite primitive still compared to some of the things said in that article.
> 
> 
>> I would also like to say that going to a language lower that C is working backwards. There was a reason languages have begun to abstract hardware features in cost to efficiency. Its to much coding for trivial things. It sounds as though he wanted a code base where people could take optimized code for these trivial tasks. My question is why doesn't he start this, he already has a language, asm is the lower level C.<
> 
> I am not advocating the creation of a new language between ASM and C. ASM can be used in D code already, but it may require too much work (the nice High Level Assembly too: http://webster.cs.ucr.edu/AsmTools/HLA/). And it looks like C is less and less able to use well the features of the modern CPUs. Sometimes even the VM of C# 3.0 is able to automatically use hardware better than "easy" C compiled with GCC... So maybe some things can be added to D to allow a better usage of the modern CPU, such things aren't useful for the whole program and for trivial tasks, but only for the small speed-critical parts of the D code where you may need max speed (like tight loops, etc) (where some people today are already using ASM in the middle of D code, so the readability my improve). (The disadvantage is this may increase the language complexity, but not much the compiler complexity).
> 
> Bye,
> bearophile

I think there will be a lot of specific but common cases in which some 
assembly tricks like they mention would result in a significant speed 
increase. These will probably be relatively difficult for the compiler 
to suss out. I think a library of templates containing inline asm is the 
way to go: you get most of the benefits of custom-crafted assembly, and 
quite possibly better than you yourself could write, but you don't have 
to spend the time writing assembly every time you encounter a similar 
problem.

The only problem is that combining these may not be nearly as efficient 
as writing the code manually. I'm sure there's a workaround, though.