By splitting the `FnSig` within `TyKind::FnPtr` into `FnSigTys` and
`FnHeader`, which can be packed more efficiently. This reduces the size
of the hot `TyKind` type from 32 bytes to 24 bytes on 64-bit platforms.
This reduces peak memory usage by a few percent on some benchmarks. It
also reduces cache misses and page faults similarly, though this doesn't
translate to clear cycles or wall-time improvements on CI.
There are some comments describing multiple subsequent `use` items. When
the big `use` reformatting happens some of these `use` items will be
reordered, possibly moving them away from the comment. With this
additional level of formatting it's not really feasible to have comments
of this type. This commit removes them in various ways:
- merging separate `use` items when appropriate;
- inserting blank lines between the comment and the first `use` item;
- outright deletion (for comments that are relatively low-value);
- adding a separate "top-level" comment.
We also entirely skip formatting for four library files that contain
nothing but `pub use` re-exports, where reordering would be painful.
Remove the unstable `extern "wasm"` ABI (`wasm_abi` feature tracked
in #83788).
As discussed in https://github.com/rust-lang/rust/pull/127513#issuecomment-2220410679
and following, this ABI is a failed experiment that did not end
up being used for anything. Keeping support for this ABI in LLVM 19
would require us to switch wasm targets to the `experimental-mv`
ABI, which we do not want to do.
It should be noted that `Abi::Wasm` was internally used for two
things: The `-Z wasm-c-abi=legacy` ABI that is still used by
default on some wasm targets, and the `extern "wasm"` ABI. Despite
both being `Abi::Wasm` internally, they were not the same. An
explicit `extern "wasm"` additionally enabled the `+multivalue`
feature.
I've opted to remove `Abi::Wasm` in this patch entirely, instead
of keeping it as an ABI with only internal usage. Both
`-Z wasm-c-abi` variants are now treated as part of the normal
C ABI, just with different different treatment in
adjust_for_foreign_abi.
The internal function was unsound, it could cause UB in rare cases where
the user inadvertly stored the returned object in a location that could
outlive the TyCtxt.
In order to make it safe, we now take a type context as an argument to
the internal fn, and we ensure that interned items are lifted using the
provided context.
Thus, this change ensures that the compiler can properly enforce
that the object does not outlive the type context it was lifted to.
This change introduces a new module to StableMIR named `abi` with
information from `rustc_target::abi` and `rustc_abi`, that allow users
to retrieve more low level information required to perform
bit-precise analysis.
The layout of a type can be retrieved via `Ty::layout`, and the instance
ABI can be retrieved via `Instance::fn_abi()`.
To properly handle errors while retrieve layout information, we had
to implement a few layout related traits.
In cases like Kani, we will invoke the rustc_internal run command
directly for now. It would be handly to be able to have a callback
that can return a value.
We also need extra methods to convert stable constructs into internal
ones, so we can break down the transition into finer grain commits.
We are not planning to support user generated constant in the
foreseeable future, so we are removing the Fold logic for now in
favor of the Instance::resolve logic.
The Instance::resolve was however incomplete, since we weren't handling
internalizing constants yet. Thus, I added that.
I decided to keep the Const fields private in case we decide to
translate them lazily.
The `Instance::body()` returns a monomorphized body.
For that, we had to implement visitor that monomorphize types and
constants. We are also introducing the RustcInternal trait that will
allow us to convert back from Stable to Internal.
Note that this trait is not yet visible for our users as it depends on
Tables. We should probably add a new trait that can be exposed.
