Compute a bucket hash and use it in the cache path to avoid grouping entries
that will never make sense together. Don't trust the path, though, and also
lace it into the keys themselves, so that eg. a RO cache miss can never turn
into corruption.
Keep a readable metadata entry at the beginning of the cache, with readable
version, bitness and serialized config.
Use printable characters in FOZ key names as intended.
FEX Relocations now live at an offset from the `CodeData.BlockBegin` of the
code. Regardless of where the relocation moves to, it should always be
relative to that address. This is what makes it PIC compatible.
We were preemptively offsetting the relocation location to be relative
to the memory base in the buffer, which is unnecessary and causes code
caching to basically relocate twice to get the real location.
So in JIT.cpp, stop relocating the offsets, they're already relative to
`BlockBegin`, which is offset 0.
Then when storing the relocation, stop relocating offsets AGAIN because it's
already relative to the code being serialized.
Then when loading the relocations in `CodeCache::ApplyCodeRelocations`
stop relocating offsets YET ANOTHER TIME.
All this is to say that relocation offsets are already PIC and relative
to offset 0, so we don't need to do it three times.
With all Stores happening on the same thread now, we can also make locking
more granular for extra perf. Move to positioned IO for everything, as we
can't reliably track the cursor with that faster locking model.
Add some bounds checking to index population to protect against corruption.
Serializes code blocks to disk - only blocks coming from known regions, for now
Disabled by default, key and versioning still needs work, but works for testing
Pierre-Loup A. Griffais