Perform simple scalar replacement of aggregates (SROA) MIR opt
This is a re-open of https://github.com/rust-lang/rust/pull/85796
I copied the debuginfo implementation (first commit) from `@eddyb's` own SROA PR.
This pass replaces plain field accesses by simple locals when possible.
To be eligible, the replaced locals:
- must not be enums or unions;
- must not be used whole;
- must not have their address taken.
The storage and deinit statements are duplicated on each created local.
cc `@tmiasko` who reviewed the former version of this PR.
interpret: support for per-byte provenance
Also factors the provenance map into its own module.
The third commit does the same for the init mask. I can move it in a separate PR if you prefer.
Fixes https://github.com/rust-lang/miri/issues/2181
r? `@oli-obk`
Rollup of 9 pull requests
Successful merges:
- #103439 (Show note where the macro failed to match)
- #103734 (Adjust stabilization version to 1.65.0 for wasi fds)
- #104148 (Visit attributes of trait impl items during AST validation)
- #104241 (Move most of unwind's build script to lib.rs)
- #104258 (Deduce closure signature from a type alias `impl Trait`'s supertraits)
- #104296 (Walk types more carefully in `ProhibitOpaqueTypes` visitor)
- #104309 (Slightly improve error message for invalid identifier)
- #104316 (Simplify suggestions for errors in generators.)
- #104339 (Add `rustc_deny_explicit_impl`)
Failed merges:
- #103484 (Add `rust` to `let_underscore_lock` example)
r? `@ghost`
`@rustbot` modify labels: rollup
Deduce closure signature from a type alias `impl Trait`'s supertraits
r? `@oli-obk`
Basically pass the TAIT's bounds through the same method that we're using to deduce a signature from infer var closure bounds.
Does this need a new FCP? I see it as a logical extension of #101834, but happy to rfcbot a new one if it does.
Add new MIR constant propagation based on dataflow analysis
The current constant propagation in `rustc_mir_transform/src/const_prop.rs` fails to handle many cases that would be expected from a constant propagation optimization. For example:
```rust
let x = if true { 0 } else { 0 };
```
This pull request adds a new constant propagation MIR optimization pass based on the existing dataflow analysis framework. Since most of the analysis is not unique to constant propagation, a generic framework has been extracted. It works on top of the existing framework and could be reused for other optimzations.
Closes#80038. Closes#81605.
## Todo
### Essential
- [x] [Writes to inactive enum variants](https://github.com/rust-lang/rust/pull/101168#pullrequestreview-1089493974). Resolved by rejecting the registration of places with downcast projections for now. Could be improved by flooding other variants if mutable access to a variant is observed.
- [X] Handle [`StatementKind::CopyNonOverlapping`](https://github.com/rust-lang/rust/pull/101168#discussion_r957774914). Resolved by flooding the destination.
- [x] Handle `UnsafeCell` / `!Freeze` correctly.
- [X] Overflow propagation of `CheckedBinaryOp`: Decided to not propagate if overflow flag is `true` (`false` will still be propagated)
- [x] More documentation in general.
- [x] Arguments for correctness, documentation of necessary assumptions.
- [x] Better performance, or alternatively, require `-Zmir-opt-level=3` for now.
### Extra
- [x] Add explicit unreachability, i.e. upgrading the lattice from $\mathbb{P} \to \mathbb{V}$ to $\set{\bot} \cup (\mathbb{P} \to \mathbb{V})$.
- [x] Use storage statements to improve precision.
- [ ] Consider opening issue for duplicate diagnostics: https://github.com/rust-lang/rust/pull/101168#issuecomment-1276609950
- [ ] Flood moved-from places with $\bot$ (requires some changes for places with tracked projections).
- [ ] Add downcast projections back in.
- [ ] [Algebraic simplifications](https://github.com/rust-lang/rust/pull/101168#discussion_r957967878) (possibly with a shared API; done by old const prop).
- [ ] Propagation through slices / arrays.
- [ ] Find other optimizations that are done by old `const_prop.rs`, but not by this one.
Resolve lifetimes independently for each item-like.
Now that the heavy-lifting is done on the AST and during lowering, we do not need to perform HIR lifetime resolution on a full item at once. Instead, we can treat each item-like independently, and look at `generics_of` the parent exceptionally for associated items.
Use `const_error_with_guaranteed` more
Better to pass down an ErrorGuaranteed rather than making a new one out of thin air, for some usages. Also for the ones where we *do* need to delay a bug, that delayed bug will have a more descriptive message.
Add support for custom mir
This implements rust-lang/compiler-team#564 . Details about the design, motivation, etc. can be found in there.
r? ```@oli-obk```
Rollup of 7 pull requests
Successful merges:
- #100508 (avoid making substs of type aliases late bound when used as fn args)
- #101381 (Test that target feature mix up with homogeneous floats is sound)
- #103353 (Fix Access Violation when using lld & ThinLTO on windows-msvc)
- #103521 (Avoid possible infinite loop when next_point reaching the end of file)
- #103559 (first move on a nested span_label)
- #103778 (Update several crates for improved support of the new targets)
- #103827 (Properly remap and check for substs compatibility in `confirm_impl_trait_in_trait_candidate`)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Better error for HRTB error from generator interior
cc #100013
This is just a first pass at an error. It could be better, and shouldn't really be emitted in the first place. But this is better than what was being emitted before.
selection failure: recompute applicable impls
The way we currently skip errors for ambiguous trait obligations seems pretty fragile so we get some duplicate errors because of this.
Removing this info from selection errors changes this system to be closer to my image of our new trait solver and is also making it far easier to change overflow errors to be non-fatal ✨
r? types cc `@estebank`
resolve: More detailed effective visibility tracking for imports
Per-`DefId` tracking is not enough, due to glob imports in particular, which have a single `DefId` for the whole glob import item.
We need to track this stuff per every introduced name (`NameBinding`).
Also drop `extern` blocks from the effective visibility table, they are nominally private and it doesn't make sense to keep them there.
Later commits add some debug-only invariant checking and optimiaztions to mitigate regressions in https://github.com/rust-lang/rust/pull/103965#issuecomment-1304256445.
This is a bugfix and continuation of https://github.com/rust-lang/rust/pull/102026.
