Slow code, slow

[ketmar]

H. S. Teoh wrote:

> On Mon, Feb 26, 2018 at 08:38:39PM +0200, ketmar via Digitalmars-d wrote:
>> H. S. Teoh wrote:
>> 
>>> On Sat, Feb 24, 2018 at 09:43:35AM +0000, Stefan Koch via Digitalmars-d
>>> wrote:
>>> [...]
>>>> This particular slowdown happens because there are somehow
>>>> depdencies on std.format.format which is instantiated.  Which has
>>>> a ton of dependencies itself.
>>> Aha!  That explains it.  Thanks, Stefan, for the accurate diagnosis. :-)
>>> Now the next problem is: how to trim the fat off std.format ...
>> p.s.: and ditch type safety. 'cause `foo(T...) (T args)` is a major
>> slowdown -- it is a template. ;-)
>
> Actually, I think this is the classic example of why the compiler should
> improve the way it implements templates.
>
> In my mind, even C's printf API is sucky, because it involves runtime
> parsing of what's usually a static string, over and over again. What we
> *really* want is for something like:
>
> 	writeln("blah %d bluh %s", i, s);
>
> to be translated into something like:
>
> 	stdout.putString("blah ");
> 	stdout.putInt(i);
> 	stdout.putString(" bluh ");
> 	stdout.putString(s);
>
> I.e., there should not be Yet Another Template with Yet Another
> Ridiculously Long Argument List Type Encoded In The Mangled Name, along
> with needless marshalling of function arguments on the stack, branching
> to some other part of the code (potentially causing an instruction cache
> miss), tons of copy-pasta for calling the same old functions for
> outputting strings and formatting integers, and incurring Yet Another
> Branch Hazard when the function finally returns.
>
> And there should definitely be no silly runtime parsing of format
> strings and all of that useless dance.

i once wrote such thing (for fun, using "Functional Programming With 
Templates"). it was fun to do, and freakin' slow due to template bloat. ;-) 
but yes, it generates a string mixin, and in runtime there was no format 
string parsing.

still, we can be either smart, or have fast compile times, but not both. T_T

p.s.: oops. just found that i cannot pass structs with dtors to `(...)` 
functions. not fun at all.