As I've been trying to replace a `Vec` with an `IndexVec`, having `last` exist on both but returning very different types makes the transition a bit awkward -- the errors are later, where you get things like "there's no `ty` method on `mir::Field`" rather than a more localized error like "hey, there's no `last` on `IndexVec`".
So I propose renaming `last` to `last_index` to help distinguish `Vec::last`, which returns an element, and `IndexVec::last_index`, which returns an index.
(Similarly, `Iterator::last` also returns an element, not an index.)
Avoid unnecessary hashing
I noticed some stable hashing being done in a non-incremental build. It turns out that some of this is necessary to compute the crate hash, but some of it is not. Removing the unnecessary hashing is a perf win.
r? `@cjgillot`
The crate hash is needed:
- if debug assertions are enabled, or
- if incr. comp. is enabled, or
- if metadata is being generated, or
- if `-C instrumentation-coverage` is enabled.
This commit avoids computing the crate hash when these conditions are
all false, such as when doing a release build of a binary crate.
It uses `Option` to store the hashes when needed, rather than
computing them on demand, because some of them are needed in multiple
places and computing them on demand would make compilation slower.
The commit also removes `Owner::hash_without_bodies`. There is no
benefit to pre-computing that one, it can just be done in the normal
fashion.
Use stable metric for const eval limit instead of current terminator-based logic
This patch adds a `MirPass` that inserts a new MIR instruction `ConstEvalCounter` to any loops and function calls in the CFG. This instruction is used during Const Eval to count against the `const_eval_limit`, and emit the `StepLimitReached` error, replacing the current logic which uses Terminators only.
The new method of counting loops and function calls should be more stable across compiler versions (i.e., not cause crates that compiled successfully before, to no longer compile when changes to the MIR generation/optimization are made).
Also see: #103877
This patch adds a `MirPass` that tracks the number of back-edges and
function calls in the CFG, adds a new MIR instruction to increment a
counter every time they are encountered during Const Eval, and emit a
warning if a configured limit is breached.
There is a number of APIs that answer dominance queries. Previously they
were named either "dominates" or "is_dominated_by". Consistently use the
"dominates" form.
No functional changes.
Remove the `..` from the body, only a few invocations used it and it's
inconsistent with rust syntax.
Use `;` instead of `,` between consts. As the Rust syntax gods inteded.
This removes the `custom` format functionality as its only user was
trivially migrated to using a normal format.
If a new use case for a custom formatting impl pops up, you can add it
back.
Replace `Body::basic_blocks()` with field access
Since the refactoring in #98930, it is possible to borrow the basic blocks
independently from other parts of MIR by accessing the `basic_blocks` field
directly.
Replace unnecessary `Body::basic_blocks()` method with a direct field access,
which has an additional benefit of borrowing the basic blocks only.
Make lowering a query
Split from https://github.com/rust-lang/rust/pull/88186.
This PR refactors the relationship between lowering and the resolver outputs in order to make lowering itself a query.
In a first part, lowering is changed to avoid modifying resolver outputs, by maintaining its own data structures for creating new `NodeId`s and so.
Then, the `TyCtxt` is modified to allow creating new `LocalDefId`s from inside it. This is done by:
- enclosing `Definitions` in a lock, so as to allow modification;
- creating a query `register_def` whose purpose is to declare a `LocalDefId` to the query system.
See `TyCtxt::create_def` and `TyCtxt::iter_local_def_id` for more detailed explanations of the design.
This makes it possible to mutably borrow different fields of the MIR
body without resorting to methods like `basic_blocks_local_decls_mut_and_var_debug_info`.
To preserve validity of control flow graph caches in the presence of
modifications, a new struct `BasicBlocks` wraps together basic blocks
and control flow graph caches.
The `BasicBlocks` dereferences to `IndexVec<BasicBlock, BasicBlockData>`.
On the other hand a mutable access requires explicit `as_mut()` call.
These links never worked, but the lint was suppressed due to the fact
that the span was pointing into the macro. With the new macro
implementation, the span now points directly to the doc comment in the
macro invocation, so it's no longer suppressed.
Specifically, change `Ty` from this:
```
pub type Ty<'tcx> = &'tcx TyS<'tcx>;
```
to this
```
pub struct Ty<'tcx>(Interned<'tcx, TyS<'tcx>>);
```
There are two benefits to this.
- It's now a first class type, so we can define methods on it. This
means we can move a lot of methods away from `TyS`, leaving `TyS` as a
barely-used type, which is appropriate given that it's not meant to
be used directly.
- The uniqueness requirement is now explicit, via the `Interned` type.
E.g. the pointer-based `Eq` and `Hash` comes from `Interned`, rather
than via `TyS`, which wasn't obvious at all.
Much of this commit is boring churn. The interesting changes are in
these files:
- compiler/rustc_middle/src/arena.rs
- compiler/rustc_middle/src/mir/visit.rs
- compiler/rustc_middle/src/ty/context.rs
- compiler/rustc_middle/src/ty/mod.rs
Specifically:
- Most mentions of `TyS` are removed. It's very much a dumb struct now;
`Ty` has all the smarts.
- `TyS` now has `crate` visibility instead of `pub`.
- `TyS::make_for_test` is removed in favour of the static `BOOL_TY`,
which just works better with the new structure.
- The `Eq`/`Ord`/`Hash` impls are removed from `TyS`. `Interned`s impls
of `Eq`/`Hash` now suffice. `Ord` is now partly on `Interned`
(pointer-based, for the `Equal` case) and partly on `TyS`
(contents-based, for the other cases).
- There are many tedious sigil adjustments, i.e. adding or removing `*`
or `&`. They seem to be unavoidable.
