which is the index of the key that already exists in the hash map.
This enables the use case of using `AutoArrayHashMap(void, void)` which
may seem surprising at first, but is actually pretty handy!
This commit includes a proof-of-concept of how I want to use it, with a
new InternArena abstraction for stage2 that provides a compact way to
store values (and types) in an "internment arena", thus making types
stored exactly once (per arena), representable with a single u32 as a
reference to a type within an InternArena, and comparable with a
simple u32 integer comparison. If both types are in the same
InternArena, you can check if they are equal by seeing if their index is
the same.
What's neat about `AutoArrayHashMap(void, void)` is that it allows us to
look up the indexes by key, *without actually storing the keys*.
Instead, keys are treated as ephemeral values that are constructed as
needed.
As a result, we have an extremely efficient encoding of types and
values, represented only by three arrays, which has no pointers, and can
therefore be serialized and deserialized by a single writev/readv call.
The `map` field is denormalized data and can be computed from the other
two fields.
This is in contrast to our current Type/Value system which makes
extensive use of pointers.
The test at the bottom of InternArena.zig passes in this commit.
These changes have been made to resolve issue #10037. The `Random`
interface was implemented in such a way that causes significant slowdown
when calling the `fill` function of the rng used.
The `Random` interface is no longer stored in a field of the rng, and is
instead returned by the child function `random()` of the rng. This
avoids the performance issues caused by the interface.
We already have a LICENSE file that covers the Zig Standard Library. We
no longer need to remind everyone that the license is MIT in every single
file.
Previously this was introduced to clarify the situation for a fork of
Zig that made Zig's LICENSE file harder to find, and replaced it with
their own license that required annual payments to their company.
However that fork now appears to be dead. So there is no need to
reinforce the copyright notice in every single file.
This breaking change disambiguates between overriding the lib dir when
performing an installation with the Zig Build System, and overriding the
lib dir that the Zig installation itself uses.
Conflicts:
* doc/langref.html.in
* lib/std/enums.zig
* lib/std/fmt.zig
* lib/std/hash/auto_hash.zig
* lib/std/math.zig
* lib/std/mem.zig
* lib/std/meta.zig
* test/behavior/alignof.zig
* test/behavior/bitcast.zig
* test/behavior/bugs/1421.zig
* test/behavior/cast.zig
* test/behavior/ptrcast.zig
* test/behavior/type_info.zig
* test/behavior/vector.zig
Master branch added `try` to a bunch of testing function calls, and some
lines also had changed how to refer to the native architecture and other
`@import("builtin")` stuff.
auto_hash must be extra careful when hashing integers whose bit size is
not a multiple of 8 as, when reinterpreted with mem.asBytes, may contain
undefined non-zero bits too.
Speed up a little the slicing-by-8 code path by replacing the
(load+shift+xor)*4 sequence with a single u32 load plus a xor.
Before:
```
iterative: 1018 MiB/s [000000006c3b110d]
small keys: 1075 MiB/s [0035bf3dcac00000]
```
After:
```
iterative: 1114 MiB/s [000000006c3b110d]
small keys: 1324 MiB/s [0035bf3dcac00000]
```
