The existing names have bugged me for a while. Changes:
- `CycleError` -> `Cycle`. Because we normally use "error" for a `Diag`
with `Level::Error`, and this type is just a precursor to that. Also,
many existing locals of this type are already named `cycle`.
- `CycleError::cycle` -> `Cycle::frames`. Because it is a sequence of
frames, and we want to avoid `Cycle::cycle` (and `cycle.cycle`).
- `cycle_error` -> `find_and_handle_cycle`. Because that's what it does.
The existing name is just a non-descript noun phrase.
- `mk_cycle` -> `handle_cycle`. Because it doesn't make the cycle; the
cycle is already made. It handles the cycle, which involves (a)
creating the error, and (b) handling the error.
- `report_cycle` -> `create_cycle_error`. Because that's what it does:
creates the cycle error (i.e. the `Diag`).
- `value_from_cycle_error` -> `handle_cycle_error_fn`. Because most
cases don't produce a value, they just emit an error and quit.
And the `_fn` suffix is for consistency with other vtable fns.
- `from_cycle_error` -> `handle_cycle_error`. A similar story for this
module.
Overhaul `ensure_ok`
The interaction of `ensure_ok` and the `return_result_from_ensure_ok` query modifier is weird and hacky. This PR cleans it up. Details in the individual commits.
r? @Zalathar
`ensure_ok` provides a special, more efficient way of calling a query
when its return value isn't needed. But there is a complication: if the
query is marked with the `return_result_from_ensure_ok` modifier, then
it will return `Result<(), ErrorGuaranteed`. This is clunky and feels
tacked on. It's annoying to have to add a modifier to a query to declare
information present in its return type, and it's confusing that queries
called via `ensure_ok` have different return types depending on the
modifier.
This commit:
- Eliminates the `return_result_from_ensure_ok` modifier. The proc macro
now looks at the return type and detects if it matches `Result<_,
ErrorGuarantee>`. If so, it adds the modifier
`returns_error_guaranteed`. (Aside: We need better terminology to
distinguish modifiers written by the user in a `query` declaration
(e.g. `cycle_delayed_bug`) from modifiers added by the proc macro
(e.g. `cycle_error_handling`.))
- Introduces `ensure_result`, which replaces the use of `ensure_ok` for
queries that return `Result<_, ErrorGuarantee>`. As a result,
`ensure_ok` can now only be used for the "ignore the return value"
case.
Instead of defaulting to `None` it now defaults to `Align::ONE` i.e.
no alignment restriction. Codegen test changes are due to us now skipping
`align 1` annotations (they are useless; not skipping them makes all the
raw pointers gain an `align 1` annotation which doesn't seem any good)
Make `size`/`align` always correct rather than conditionally on the
`safe` field. This makes it less error prone and easier to work with for
`MaybeDangling` / potential future pointer kinds like `Aligned<_>`.
As a performance optimization, we altogether avoid ever invoking the
query that computes an Instance fn's fully optimized ABI in cases where
the build will not actually deduce parameter attributes.
`fn_abi_of_instance` can look at function bodies to deduce codegen
optimization attributes (namely `ArgAttribute::ReadOnly` and
`ArgAttribute::CapturesNone`) of indirectly-passed parameters. This can
lead to cycles when performed during typeck, when such attributes are
irrelevant.
This patch breaks a subquery out from `fn_abi_of_instance`,
`fn_abi_of_instance_no_deduced_attrs`, which returns the ABI before such
parameter attributes are deduced; and that new subquery is used in CTFE
instead.
This variant was a fallback value used to continue analysis after a
`Representability` error, but it's no longer needed thanks to the
previous commit. This means `Representability` can now be reduced to a
unit type that exists just so `FromCycleError` can exist for the
`representability` query. (There is potential for additional cleanups
here, but those are beyond the scope of this PR.)
This means the `representability`/`representability_adt_ty` queries no
longer have a meaningful return value, i.e. they are check-only queries.
So they now have a `check_` prefix added. And the `rtry!` macro is no
longer needed.
perf(codegen): Restore `noundef` On `PassMode::Cast` Args In Rust ABI
### Summary:
#### Problem:
Small aggregate arguments passed via `PassMode::Cast` in the Rust ABI (e.g. `[u32; 2]` cast to `i64`) are missing `noundef` in the emitted LLVM IR, even when the type contains no uninit bytes:
```rust
#[no_mangle]
pub fn f(v: [u32; 2]) -> u32 { v[0] }
```
```llvm
; expected: define i32 @f(i64 noundef %0)
; actual: define i32 @f(i64 %0) ← noundef missing
```
This blocks LLVM from applying optimizations that require value-defined semantics on function arguments.
#### Root Cause:
`adjust_for_rust_abi` calls `arg.cast_to(Reg::Integer)`, which internally creates a `CastTarget` with `ArgAttributes::new()` — always empty. Any validity attribute that was present before the cast is silently dropped.
This affects all `PassMode::Cast` arguments and return values in the Rust ABI: plain arrays, newtype wrappers, and any `BackendRepr::Memory` type small enough to fit in a register.
A prior attempt (rust-lang/rust#127210) used `Ty`/`repr` attributes to detect padding.
#### Solution:
After `adjust_for_rust_abi`, iterate all `PassMode::Cast` args and the return value. For each, call `layout_is_noundef` on the original layout; if it returns `true`, set `NoUndef` on the `CastTarget`'s `attrs`.
`layout_is_noundef` uses only the computed layout — `BackendRepr`, `FieldsShape`, `Variants`, `Scalar::is_uninit_valid()` — and never touches `Ty` or repr attributes. **Anything it cannot prove returns `false`.**
Covered cases:
- `Scalar` / `ScalarPair` (both halves initialized, fields contiguous)
- `FieldsShape::Array` (element type recursively uninit-free)
- `FieldsShape::Arbitrary` with `Variants::Single` (fields cover `0..size` with no gaps, each recursively uninit-free) — handles newtype wrappers, multi-field structs, single-variant enums, `repr(transparent)`, `repr(C)` wrappers
Conservatively excluded with FIXMEs:
- Multi-variant enums (per-variant padding analysis needed)
- Foreign-ABI casts (cast target may exceed layout size, needs a size guard)
### Changes:
- `compiler/rustc_ty_utils/src/abi.rs`: add restoration loop after `adjust_for_rust_abi`; add `layout_is_noundef` and `fields_cover_layout`.
- `tests/codegen-llvm/abi-noundef-cast.rs`: new FileCheck test covering arrays, newtype wrappers (`repr(Rust)`, `repr(transparent)`, `repr(C)`), multi-field structs, single-variant enums, return values, and negative cases (`MaybeUninit`, struct with trailing padding).
- `tests/codegen-llvm/debuginfo-dse.rs`: update one CHECK pattern — `Aggregate_4xi8` (`struct { i8, i8, i8, i8 }`) now correctly gets `noundef`.
Fixesrust-lang/rust#123183.
r? @RalfJung
refactor(mgca): Change `DefKind::Const` and `DefKind::AssocConst` to have a `is_type_const` flag
Addresses rust-lang/rust#152940
- Changed `DefKind::Const` and `DefKind::AssocConst` to have a `is_type_const` flag.
- changed `is_type_const` query to check for this flag
- removed `is_rhs_type_const` query
r? @BoxyUwU
* refactor: add `is_type_const` flag to `DefKind::Const` and `AssocConst`
* refactor(cleanup) remove the `rhs_is_type_const` query
* style: fix formatting
* refactor: refactor stuff in librustdoc for new Const and AssocConst
* refactor: refactor clippy for the changes
* chore: formatting
* fix: fix test
* fix: fix suggestions
* Update context.rs
Co-authored-by: Boxy <rust@boxyuwu.dev>
* changed AssocKind::Const to store data about being a type const
`adjust_for_rust_abi` was casting small aggregates to an integer register
without propagating `noundef`, causing a performance regression (#123183)
— LLVM could no longer assume the bits were fully defined.
Add `layout_is_noundef` (conservative) + `fields_are_noundef` helper,
then use `cast_to_with_attrs` to forward `NoUndef` when proven:
Scalar → `!is_uninit_valid()`
ScalarPair → both scalars valid + `s1.size + s2.size == layout.size`
(size equality rejects layouts with inter-scalar padding)
Array → recurse into element; empty arrays unconditionally noundef
Arbitrary → `Variants::Single` required; walk fields in offset order —
any gap, non-noundef field, or trailing pad returns false
Union / Primitive / Simd → false (conservative)
Bless `pass-indirectly-attr.stderr` and `debuginfo-dse.rs` for the new
attribute on Cast args. Add `tests/codegen-llvm/abi-noundef-cast.rs`
covering positive Cast cases (arrays, plain structs, single-variant enum)
and negative Cast cases (MaybeUninit, multi-variant enum, field/pair gap,
trailing padding).
Fixes#123183.
Co-authored-by: Ralf Jung <post@ralfj.de>
Implement RFC 3678: Final trait methods
Tracking: https://github.com/rust-lang/rust/issues/131179
This PR is based on rust-lang/rust#130802, with some minor changes and conflict resolution.
Futhermore, this PR excludes final methods from the vtable of a dyn Trait.
And some excerpt from the original PR description:
> Implements the surface part of https://github.com/rust-lang/rfcs/pull/3678.
>
> I'm using the word "method" in the title, but in the diagnostics and the feature gate I used "associated function", since that's more accurate.
cc @joshtriplett
UnsafePinned: implement opsem effects of UnsafeUnpin
This implements the next step for https://github.com/rust-lang/rust/issues/125735: actually making `UnsafePinned` have special opsem effects by suppressing the `noalias` *even if* the type is wrapped in an `Unpin` wrapper.
For backwards compatibility we also still keep the `Unpin` hack, i.e. a type must be both `Unpin` and `UnsafeUnpin` to get `noalias`.
aliases may be rigid even if they don't reference params. If the alias isn't well-formed, trying to normalize it as part of the input should have already failed
Nicholas Nethercote