Store sharer and eraser in function prefix

[serkm]

This reduces the size of frame headers for faster PushFrame/Return.
Non-linear handlers get slower though, because now there is an additional indirection for sharers/erasers.

[serkm]

I also moved vtables to function prefixes.
This removes one indirection for the first operator of an object.

Here are some benchmark results:

[b-studios]

How does this lead to an additional indirection? I would have assumed it would just be an additional offset computation.

[serkm]

Previously it was:
Load stack pointer -> add offset -> load sharer address

Now it is:
Load stack pointer -> add offset -> load return address -> add offset -> load sharer address

[b-studios]

Hmm... I expected it to be

Load stack pointer -> add offset -> load return address -> add offset

but maybe my mental model of how LLVM works is just off here, or you implemented a different variant than I had in mind (where the sharers and erasers are always placed at a particular offset of the return address in code).

[serkm]

I didn't see an easy way to place functions relative to each other.
I placed function pointers relative to the return address.

[b-studios]

ok, then the additional indirection makes sense, thanks for the explanation

[b-studios]

Is there a way to make the linker happy?