Michael Schellenberger Costa

> Does this PR replace #883 and #840? Yes, that is the goal

Yeah, I am not fully ready with the device side memory resources. I hope to finish something this week

Yeah that is super interesting to see, I am really curious as to where that difference could come from. It should boil down to the same thing

I believe the issue is that i call the function `_Dynamic_index` rather than memoizing it in an array and indexing that

Note turning the loopy function into a static array indeed improved optimizations https://godbolt.org/z/GEx8Ee71j

Generally speaking I am extremely concerned about the implementation complexity here. I only looked at `extends` in detail, because I did implement it [previously](https://godbolt.org/z/T9T4db864). Especially compile times are going to...

Yeah I believe my `_Dynamic_index` function is the issue, I will try to memoize that in a second static array, so there is no runtime cost

@wmaxey Is this something we still want given the current blossom infra we have?

@ericniebler @allisonvacanti Is this ready to merge?

Hm that one is strange: ``` /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/ext/numeric_traits.h(70): error: qualified name is not allowed /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/ext/numeric_traits.h(72): error: expected a "(" /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/ext/numeric_traits.h(72): error: expected a type specifier /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/ext/numeric_traits.h(72): error: expected a ")" /usr/bin/../lib/gcc/x86_64-linux-gnu/9/../../../../include/c++/9/ext/numeric_traits.h(76):...