I had tried unrolling the loops to avoid requiring the
`vector_store_elem` instruction, but it's arguably a problem to generate
O(N) code for an operation on `@Vector(N, T)`. In addition, that
lowering emitted a lot of `.aggregate_init` instructions, which is
itself a quite difficult operation to codegen.
This requires reintroducing runtime vector indexing internally. However,
I've put it in a couple of instructions which are intended only for use
by `Air.Legalize`, named `legalize_vec_elem_val` (like `array_elem_val`,
but for indexing a vector with a runtime-known index) and
`legalize_vec_store_elem` (like the old `vector_store_elem`
instruction). These are explicitly documented as *not* being emitted by
Sema, so need only be implemented by backends if they actually use an
`Air.Legalize.Feature` which emits them (otherwise they can be marked as
`unreachable`).
`__addosi4`, `__addodi4`, `__addoti4`, `__subosi4`, `__subodi4`, and
`__suboti4` were all functions which we invented for no apparent reason.
Neither LLVM, nor GCC, nor the Zig compiler use these functions. It
appears the functions were created in a kind of misunderstanding of an
old language proposal; see https://github.com/ziglang/zig/pull/10824.
There is no benefit to these functions existing; if a Zig compiler
backend needs this operation, it is trivial to implement, and *far*
simpler than calling a compiler-rt routine. Therefore, this commit
deletes them. A small amount of that code was used by other parts of
compiler-rt; the logic is trivial so has just been inlined where needed.
I also chose to quickly implement `__addvdi3` (a standard function)
because it is trivial and we already implement the `sub` parallel.
I started this diff trying to remove a little dead code from the C
backend, but ended up finding a bunch of dead code sprinkled all over
the place:
* `packed` handling in the C backend which was made dead by `Legalize`
* Representation of pointers to runtime-known vector indices
* Handling for the `vector_store_elem` AIR instruction (now removed)
* Old tuple handling from when they used the InternPool repr of structs
* Straightforward unused functions
* TODOs in the LLVM backend for features which Zig just does not support
The main goal of this change was to avoid emitting the
`vector_store_elem` AIR tag, because this represents an operation which
Zig no longer supports (and hence Sema no longer emits) as of 010d9a6
(because runtime vector indices are now forbidden). Backends should not
need to lower this operation, so I rewrote the legalizations which
emitted it (scalarizations of vector operations) to instead unroll the
loop and hence emit comptime-known vector indices.
In doing this, I actually reworked those legalizations to use a
different strategy; instead of using an `alloc` and storing to
individual vector elements, the vector is constructed by-val, for
instance by performing the scalar operation on all elements and passing
them to an `aggregate_init`. This is vastly simpler to implement in
Legalize, conceptually simpler, and doesn't severely pessimise memory
usage, because a non-optimizing backend will store the full vector on
the stack either way.
Given the above rationale, I also ended up reworking several other
legalizations to use simpler lowerings. The legalizations in question
were bitcast scalarization, `struct_field_val` of `packed struct`s
(where we just bitcast to an integer and perform the appropriate
shift/trunc sequence), and `aggregate_init` of a `packed struct` (also
implemented in terms of integer bitwise operations with bitcasts to and
from the actual types). This hugely simplified some parts of `Legalize`.
So, `Legalize` is now much simpler, and the `vector_store_elem`
instruction is no longer emitted by any part of the compiler so can be
removed in a future commit.
ML-DSA is a post-quantum signature scheme that was recently
standardized by NIST.
Keys and signatures are pretty large, not making it a drop-in
replacement for classical signature schemes.
But if you are shipping keys that may still be used in 10 years
or whenever large quantum computers able to break ECC arrive,
it that ever happens, and you don't have the ability to replace
these keys, ML-DSA is for you.
Performance is great, verification is faster than Ed25519 / ECDSA.
I tried manual vectorization, but it wasn't worth it, the compiler
does at good job at auto-vectorization already.
This configuration hasn't had much work put into it yet, so is all but
guaranteed to miscompile or crash. Since users are starting to try out
`-fincremental`, and LLVM is still the default backend in many cases,
it's worth having this warning to avoid bug reports like
https://github.com/ziglang/zig/issues/25873.
To match the new default implementation. In fact, I implemented this by
simply dispatching *to* the default implementation after the debug log
guard; no need to complicate things!
This change removes the ref_start_index from the possible enum values of
Index and OptionalIndex. It is not really a index, but a constant that
tells the offset of static Refs, so lets move it where such constant
belongs i.e. to the Ref.
Since the child process is spawned with the tmp directory as its CWD, the child process opens it without DELETE access. On error, the child process would still be alive while the tmp directory is attempting to be deleted, so it would fail with `.SHARING_VIOLATION => return error.FileBusy`.
Fixes arguably the least important part of #22510, since it's only the directory itself that would fail to get deleted, all the files inside would get deleted just fine.
