Add `ODIN_PLATFORM_SUBTARGET_IOS` builtin constant which evaluated to
`true` when the platform is `Darwin` and the subtarget it either `iPhone` or `iPhoneSimulator`
It has been discovered that AddressSanitizer does not keep a 1:1 mapping
of which bytes are poisoned and which are not. This can cause issues for
allocations less than 8 bytes and where addresses straddle 8-byte
boundaries.
See the following link for more information:
https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm#mapping
`typeid` used to be a fancy index with extra metadata stored on it. Now it is direct hash of the type.
This is safe to do in practice since any possible collisions are checked at compile time AND the chances of having a 1% collision are around 1 in 600K (see the Birthday Paradox).
Therefore accessing a `^Type_Info` is now a hash table lookup with linear probing. The table is twice the size than necessary so prevent too much probing due to an overly dense hash table.
This affects `runtime.Arena` and `virtual.Arena`, but not currently
`mem.Arena`. These changes allow the last allocation that has been
made to be resized to a larger size by just extending their
allocation in-place, when there's sufficient room in the memory block to
do so.
Shrinking in place and re-using the rest of the allocation can be
supported using almost the same logic, but would require the memory to
be zeroed. Since this would add a additional cost that isn't currently
present, shrinking has not been changed.
`map_desired_position` does not return the actual position, probing must
be done afterwards to figure out the real position. `map_entry` did not
do this for the returned key pointer so it could point to the wrong key
if probing was done.
This provides an equivalent to `assert` and `assert_contextless` that
are always evaluated, ignoring `ODIN_DISABLE_ASSERT`, which is useful
for enforcing API contracts or "asserting" on conditionals with
side-effects.
