Anecdote 1: The generic version is way more popular than the non-generic
one in Zig codebase:
git grep -w alignForward | wc -l
56
git grep -w alignForwardGeneric | wc -l
149
git grep -w alignBackward | wc -l
6
git grep -w alignBackwardGeneric | wc -l
15
Anecdote 2: In my project (turbonss) that does much arithmetic and
alignment I exclusively use the Generic functions.
Anecdote 3: we used only the Generic versions in the Macho Man's linker
workshop.
These are frequently invalidated whenever a string is interned, so avoid
creating pointers to `string_bytes` wherever possible. This is an
attempt to fix random CI failures.
The main motivation for this commit is eliminating Decl.value_arena.
Everything else is dominoes.
Decl.name used to be stored in the GPA, now it is stored in InternPool.
It ended up being simpler to migrate other strings to be interned as
well, such as struct field names, union field names, and a few others.
This ended up requiring a big diff, sorry about that. But the changes
are pretty nice, we finally start to take advantage of InternPool's
existence.
global_error_set and error_name_list are simplified. Now it is a single
ArrayHashMap(NullTerminatedString, void) and the index is the error tag
value.
Module.tmp_hack_arena is re-introduced (it was removed in
eeff407941560ce8eb5b737b2436dfa93cfd3a0c) in order to deal with
comptime_args, optimized_order, and struct and union fields. After
structs and unions get moved into InternPool properly, tmp_hack_arena
can be deleted again.
This is neither a type nor a value. Simplifies `addStrLit` as well as
the many places that switch on `InternPool.Key`.
This is a partial revert of bec29b9e498e08202679aa29a45dab2a06a69a1e.
This is a bit odd, because this value doesn't actually exist:
see #15909. This gets all the empty enum/union behavior tests passing.
Also adds an assertion to `Sema.analyzeBodyInner` which would have
helped figure out the issue here much more quickly.
Key.PtrType is now an extern struct so that hashing it can be done by
reinterpreting bytes directly. It also uses the same representation for
type_pointer Tag encoding and the Key. Accessing pointer attributes now
requires packed struct access, however, many operations are now a copy
of a u32 rather than several independent fields.
This function moves the top two most used Key variants - pointer types
and pointer values - to use a single-shot hash function that branches
for small keys instead of calling memcpy.
As a result, perf against merge-base went from 1.17x ± 0.04 slower to
1.12x ± 0.04 slower. After the pointer value hashing was changed, total
CPU instructions spent in memcpy went from 4.40% to 4.08%, and after
additionally improving pointer type hashing, it further decreased to
3.72%.
The Zig language allows the compiler to make this optimization
automatically. We should definitely make the compiler do that, and
revert this commit. However, that will not happen in this branch, and I
want to continue to explore achieving performance parity with
merge-base. So, this commit changes all InternPool parameters to be
passed by const pointer rather than by value.
I measured a 1.03x ± 0.03 speedup vs the previous commit compiling the
(set of passing) behavior tests. Against merge-base, this commit is
1.17x ± 0.04 slower, which is an improvement from the previous
measurement of 1.22x ± 0.02.
Related issue: #13510
Related issue: #14129
Related issue: #15688
I'm not sure if this is the right place for this to happen, and
it should become obsolete when comptime mutation is rewritten
and the remaining legacy value tags are remove, so keeping this
as a separate revertable commit.
This allows some code (like struct initializers) to use interned types
while other code (such as comptime mutation) continues to use legacy
types.
With these changes, an `zig build-obj empty.zig` gets to a crash on
missing interned error union types.
One change worth noting in this commit is that `module.global_error_set`
is no longer kept strictly up-to-date. The previous code reserved
integer error values when dealing with error set types, but this is no
longer needed because the integer values are not needed for semantic
analysis unless `@errorToInt` or `@intToError` are used and therefore
may be assigned lazily.
I'm seeing a new assertion trip: the call to `enumTagFieldIndex` in the
implementation of `@Type` is attempting to query the field index of an
union's enum tag, but the type of the enum tag value provided is not the
same as the union's tag type. Most likely this is a problem with type
coercion, since values are now typed.
Another problem is that I added some hacks in std.builtin because I
didn't see any convenient way to access them from Sema. That should
definitely be cleaned up before merging this branch.
