On Friday, 28 June 2013 at 12:45:22 UTC, Marco Leise wrote:
Am Thu, 27 Jun 2013 23:24:48 +0200
schrieb "Meta" <[email protected]>:
I'm not an expert on how DMD works, but could this possibly be
done after the native code is generated
I've thought of that as well, but you have to merge templates
at an earlier stage. In case of a compiler such as GCC, the
native code is not even generated in the compiler, but an
external assembler.
That said, DMD does not create duplicate template instances
for the same parameters. I'd assume this includes "string
lambdas".
That's good to know. I wasn't sure if there were some cases when
template were ellided or not, even with the same arguments. By
string lambdas, I mean lambdas of the form sort!"a <= b" that are
heavily used in std.algorithm.
And I'm not sure what you really want to improve for
assertNotThrown. It is a unit testing function and the most
important thing at the moment seems to keep DMD's memory
consumption low, which more compile-time parameters can only
increase.
I was only using assertNotThrown as an example of a template
function where parameters that could be compile-time arguments
become run-time arguments to minimize template bloat.
Another point is that today's best compilers are good at
detecting compile-time constants already and could inline a
function with runtime parameters that are statically known.
I've once let DMD create a switch-case with 81 cases for me
and used a 100% templated function specialized for all these
cases. The result was a major slow-down from all the
compile-time arguments. Run-time arguments are just better!
That is certainly a corner case. Perhaps finding a way to fold
templates in some cases would still provide benefits in more
normal cases.
