Use `unused_generic_params` from crate metadata
Due to the way that `separate_provide_extern` interacted with the implementation of `<ty::InstanceDef<'tcx> as Key>::query_crate_is_local`, we actually never hit the foreign provider for `unused_generic_params`.
Additionally, since the *local* provider of `unused_generic_params` calls `should_polymorphize`, which always returns false if the def-id is foreign, this means that we never actually polymorphize monomorphic instances originating from foreign crates.
We don't actually encode `unused_generic_params` for items where all generics are used, so I had to tweak the foreign provider to fall back to `ty::UnusedGenericParams::new_all_used()` to avoid more ICEs when the above bugs were fixed.
Ensure value is on the on-disk cache before returning from `ensure()`.
The current logic for `ensure()` a query just checks that the node is green in the dependency graph.
However, a lot of places use `ensure()` to prevent the query from being called later. This is the case before stealing a query result.
If the query is actually green but the value is not available in the on-disk cache, `ensure` would return, but a subsequent call to the full query would run the code, and attempt to read from a stolen value.
This PR conforms the query system to the usage by checking whether the queried value is loadable from disk before returning.
Sadly, I can't manage to craft a proper test...
Should fix all instances of "attempted to read from stolen value".
Rollup of 9 pull requests
Successful merges:
- #108726 (tidy: enforce comment blocks to have an even number of backticks)
- #108797 (Allow binary files to go through the `FileLoader`)
- #108841 (Add suggestion to diagnostic when user has array but trait wants slice. (rebased))
- #108984 (bootstrap: document tidy)
- #109013 (Give proper error message when tcx wasn't passed to decoder)
- #109017 (remove duplicated calls to sort_string)
- #109018 (Expand on the allocator comment in `rustc-main`)
- #109028 (Add eslint checks for rustdoc-js tester)
- #109034 (Commit some tests for the new solver + lazy norm)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Give proper error message when tcx wasn't passed to decoder
I hit this yesterday and found it very confusing, even though the solution to the problem is very simple.
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`
Simplify message paths
This makes it easier to open the messages file. Right now I have to first click on the `locales` dir to open it, and then on the `en-US.ftl` file. `Cargo.toml` and `build.rs` files are also in the top level, and I think there should not be more than one file, so a directory isn't really needed. The [chosen strategy for pontoon adoption](https://rust-lang.zulipchat.com/#narrow/stream/336883-i18n/topic/pontoon.20and.20next.20steps) is out of tree. Even if this descision is changed in the future, the `messages.ftl` approach is also compatible with non-english translations living in-tree, as long as the non-english translations don't live in the `compiler/rustc_foo/` directories but in different ones. That would also be helpful for grepability purposes.
The commit was the result of automated changes:
```
for p in compiler/rustc_*; do mv $p/locales/en-US.ftl $p/messages.ftl; rmdir $p/locales; done
for p in compiler/rustc_*; do sed -i "s#\.\./locales/en-US.ftl#../messages.ftl#" $p/src/lib.rs; done
```
r? `@davidtwco`
This makes it easier to open the messages file while developing on features.
The commit was the result of automatted changes:
for p in compiler/rustc_*; do mv $p/locales/en-US.ftl $p/messages.ftl; rmdir $p/locales; done
for p in compiler/rustc_*; do sed -i "s#\.\./locales/en-US.ftl#../messages.ftl#" $p/src/lib.rs; done
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.
Make compressed rmeta contain compressed data length after header
Fixes#90056, which is caused by link.exe introducing padding to the `.rustc` section, since it assumes this will have no effect besides allowing it to possibly use the extra space in future links.
Implement -Zlink-directives=yes/no
`-Zlink-directives=no` will ignored `#[link]` directives while compiling a crate, so nothing is emitted into the crate's metadata. The assumption is that the build system already knows about the crate's native dependencies and can provide them at link time without these directives.
This is another way to address issue # #70093, which is currently addressed by `-Zlink-native-libraries` (implemented in #70095). The latter is implemented at link time, which has the effect of ignoring `#[link]` in *every* crate. This makes it a very large hammer as it requires all native dependencies to be known to the build system to be at all usable, including those in sysroot libraries. I think this means its effectively unused, and definitely under-used.
Being able to control this on a crate-by-crate basis should make it much easier to apply when needed.
I'm not sure if we need both mechanisms, but we can decide that later.
cc `@pcwalton` `@cramertj`
(This is a large commit. The changes to
`compiler/rustc_middle/src/ty/context.rs` are the most important ones.)
The current naming scheme is a mess, with a mix of `_intern_`, `intern_`
and `mk_` prefixes, with little consistency. In particular, in many
cases it's easy to use an iterator interner when a (preferable) slice
interner is available.
The guiding principles of the new naming system:
- No `_intern_` prefixes.
- The `intern_` prefix is for internal operations.
- The `mk_` prefix is for external operations.
- For cases where there is a slice interner and an iterator interner,
the former is `mk_foo` and the latter is `mk_foo_from_iter`.
Also, `slice_interners!` and `direct_interners!` can now be `pub` or
non-`pub`, which helps enforce the internal/external operations
division.
It's not perfect, but I think it's a clear improvement.
The following lists show everything that was renamed.
slice_interners
- const_list
- mk_const_list -> mk_const_list_from_iter
- intern_const_list -> mk_const_list
- substs
- mk_substs -> mk_substs_from_iter
- intern_substs -> mk_substs
- check_substs -> check_and_mk_substs (this is a weird one)
- canonical_var_infos
- intern_canonical_var_infos -> mk_canonical_var_infos
- poly_existential_predicates
- mk_poly_existential_predicates -> mk_poly_existential_predicates_from_iter
- intern_poly_existential_predicates -> mk_poly_existential_predicates
- _intern_poly_existential_predicates -> intern_poly_existential_predicates
- predicates
- mk_predicates -> mk_predicates_from_iter
- intern_predicates -> mk_predicates
- _intern_predicates -> intern_predicates
- projs
- intern_projs -> mk_projs
- place_elems
- mk_place_elems -> mk_place_elems_from_iter
- intern_place_elems -> mk_place_elems
- bound_variable_kinds
- mk_bound_variable_kinds -> mk_bound_variable_kinds_from_iter
- intern_bound_variable_kinds -> mk_bound_variable_kinds
direct_interners
- region
- intern_region (unchanged)
- const
- mk_const_internal -> intern_const
- const_allocation
- intern_const_alloc -> mk_const_alloc
- layout
- intern_layout -> mk_layout
- adt_def
- intern_adt_def -> mk_adt_def_from_data (unusual case, hard to avoid)
- alloc_adt_def(!) -> mk_adt_def
- external_constraints
- intern_external_constraints -> mk_external_constraints
Other
- type_list
- mk_type_list -> mk_type_list_from_iter
- intern_type_list -> mk_type_list
- tup
- mk_tup -> mk_tup_from_iter
- intern_tup -> mk_tup
`-Zlink-directives=no` will ignored `#[link]` directives while compiling a
crate, so nothing is emitted into the crate's metadata. The assumption is
that the build system already knows about the crate's native dependencies
and can provide them at link time without these directives.
This is another way to address issue # #70093, which is currently addressed
by `-Zlink-native-libraries` (implemented in #70095). The latter is
implemented at link time, which has the effect of ignoring `#[link]`
in *every* crate. This makes it a very large hammer as it requires all
native dependencies to be known to the build system to be at all usable,
including those in sysroot libraries. I think this means its effectively
unused, and definitely under-used.
Being able to control this on a crate-by-crate basis should make it much
easier to apply when needed.
I'm not sure if we need both mechanisms, but we can decide that later.
Instead of loading the Fluent resources for every crate in
`rustc_error_messages`, each crate generates typed identifiers for its
own diagnostics and creates a static which are pulled together in the
`rustc_driver` crate and provided to the diagnostic emitter.
Signed-off-by: David Wood <david.wood@huawei.com>
Add rpitit queries
This is part of the changes we are making to lower RPITITs as an associated type. The rest of the stuff will follow under a `-Z` flag.
I still need to add comments to the code, explain stuff and also I'd need to avoid encoding in metadata when rpitit queries return `&[]`
r? `@compiler-errors`
There are several `mk_foo`/`intern_foo` pairs, where the former takes an
iterator and the latter takes a slice. (This naming convention is bad,
but that's a fix for another PR.)
This commit changes several `mk_foo` occurrences into `intern_foo`,
avoiding the need for some `.iter()`/`.into_iter()` calls. Affected
cases:
- mk_type_list
- mk_tup
- mk_substs
- mk_const_list
Switch to `EarlyBinder` for `type_of` query
Part of the work to finish #105779 and implement https://github.com/rust-lang/types-team/issues/78.
Several queries `X` have a `bound_X` variant that wraps the output in `EarlyBinder`. This adds `EarlyBinder` to the return type of the `type_of` query and removes `bound_type_of`.
r? `@lcnr`
Enable new rlib in non stable cases
If bundled static library uses cfg (unstable) or whole-archive (wasn't supported) bundled libs are packed even without packed_bundled_libs.
r? `@petrochenkov`
Adds the extended error documentation for E0523 to indicate that the
error is no longer produced by the compiler.
Update the E0464 documentation to include example code that produces the
error.
Remove the error message E0523 from the compiler and replace it with an
internal compiler error.
Change wording from "nullable" to "default".
Introduce a trait `IsDefault` for detecting values that are encoded as zeros or not encoded at all.
Add panics to impossible cases.
Some other minor cleanups.
rustdoc: Collect "rustdoc-reachable" items during early doc link resolution
This pass only needs to know about visibilities, attributes and reexports, so it can be run early, similarly to `compute_effective_visibilities` in rustc.
Results of this pass can be used to prune the list of extern impls early thus improving performance of https://github.com/rust-lang/rust/pull/94857.
rustc_metadata: Fix `encode_attrs`
This function didn't do what the authors intended it to do.
- Due to `move` in the closure `is_public` wasn't captured by mutalbe reference and wasn't used as a cache.
- Due to iterator cloning all the `should_encode_attr` logic run for the second time to calculate `may_have_doc_links`
This PR fixes these issues, and calculates all the needed attribute flags in one go.
(Noticed while implementing https://github.com/rust-lang/rust/pull/107136.)
This function didn't do what the authors intended it to do.
- Due to `move` in the closure `is_public` wasn't captured by mutalbe reference and wasn't used as a cache.
- Due to iterator cloning all the `should_encode_attr` logic run for the second time to calculate `may_have_doc_links`
This PR fixes these issues, and calculates all the needed attribute flags in one go.
This is a convenience feature for cases in which "no value in the table" and "default value in the table" are equivalent.
Tables using `Table<DefIndex, ()>` are migrated in this PR, some other cases can be migrated later.
This helps `DocFlags` in https://github.com/rust-lang/rust/pull/107136 in particular.
To retrieve these flags rustdoc currently has to mass decode full attributes for items in the whole crate tree, so it's better to pre-compute it in advance.
This is especially for short-term performance of https://github.com/rust-lang/rust/pull/107054 because resolver cannot use memoization of query results yet.
Use UnordMap and UnordSet for id collections (DefIdMap, LocalDefIdMap, etc)
This PR changes the `rustc_data_structures::define_id_collections!` macro to use `UnordMap` and `UnordSet` instead of `FxHashMap` and `FxHashSet`. This should account for a large portion of hash-maps being used in places where they can cause trouble.
The changes required are moderate but non-zero:
- In some places the collections are extracted into sorted vecs.
- There are a few instances where for-loops have been changed to extends.
~~Let's see what the performance impact is. With a bit more refactoring, we might be able to get rid of some of the additional sorting -- but the change set is already big enough. Unless there's a performance impact, I'd like to do further changes in subsequent PRs.~~
Performance does not seem to be negatively affected ([perf-run here](https://github.com/rust-lang/rust/pull/106977#issuecomment-1396776699)).
Part of [MCP 533](https://github.com/rust-lang/compiler-team/issues/533).
r? `@ghost`
Convert all the crates that have had their diagnostic migration
completed (except save_analysis because that will be deleted soon and
apfloat because of the licensing problem).
Only include metadata for non-dynamic libraries in rustc-dev
The actual object code should be linked from librustc_driver.so, which is still included in rustc-dev. This saves on download time and disk usage.
Fixes https://github.com/rust-lang/rust/issues/103538
Some `compare_method` tweaks
1. Make some of the comparison functions' names more regular
2. Reduce pub scope of some of the things in `compare_method`
~3. Remove some unnecessary opaque type handling code -- `InferCtxt` already is in a mode that doesn't define opaque types~
* moved to a different PR
4. Bubble up `ErrorGuaranteed` for region constraint errors in `compare_method` - Improves a redundant error message in one unit test.
5. Move the `compare_method` module to have a more general name, since it's more like `compare_impl_item` :)
6. Rename `collect_trait_impl_trait_tys`
Remove wrapper functions for some unstable options
They are trivial and just forward to the option. Like most other options, we can just access it directly.
Stabilize default_alloc_error_handler
Tracking issue: #66741
This turns `feature(default_alloc_error_handler)` on by default, which causes the compiler to automatically generate a default OOM handler which panics if `#[alloc_error_handler]` is not provided.
The FCP completed over 2 years ago but the stabilization was blocked due to an issue with unwinding. This was fixed by #88098 so stabilization can be unblocked.
Closes#66741
Combine `ty::Projection` and `ty::Opaque` into `ty::Alias`
Implements https://github.com/rust-lang/types-team/issues/79.
This PR consolidates `ty::Projection` and `ty::Opaque` into a single `ty::Alias`, with an `AliasKind` and `AliasTy` type (renamed from `ty::ProjectionTy`, which is the inner data of `ty::Projection`) defined as so:
```
enum AliasKind {
Projection,
Opaque,
}
struct AliasTy<'tcx> {
def_id: DefId,
substs: SubstsRef<'tcx>,
}
```
Since we don't have access to `TyCtxt` in type flags computation, and because repeatedly calling `DefKind` on the def-id is expensive, these two types are distinguished with `ty::AliasKind`, conveniently glob-imported into `ty::{Projection, Opaque}`. For example:
```diff
match ty.kind() {
- ty::Opaque(..) =>
+ ty::Alias(ty::Opaque, ..) => {}
_ => {}
}
```
This PR also consolidates match arms that treated `ty::Opaque` and `ty::Projection` identically.
r? `@ghost`
Make encode_info_for_trait_item use queries instead of accessing the HIR
This change avoids accessing the HIR on `encode_info_for_trait_item` and uses queries. We will need to execute this function for elements that have no HIR and by using queries we will be able to feed for definitions that have no HIR.
r? ``@oli-obk``
Initial pass at expr/abstract const/s
Address comments
Switch to using a list instead of &[ty::Const], rm `AbstractConst`
Remove try_unify_abstract_consts
Update comments
Add edits
Recurse more
More edits
Prevent equating associated consts
Move failing test to ui
Changes this test from incremental to ui, and mark it as failing and a known bug.
Does not cause the compiler to ICE, so should be ok.
Use `as_deref` in compiler (but only where it makes sense)
This simplifies some code :3
(there are some changes that are not exacly `as_deref`, but more like "clever `Option`/`Result` method use")
`MacArgs` is an enum with three variants: `Empty`, `Delimited`, and `Eq`. It's
used in two ways:
- For representing attribute macro arguments (e.g. in `AttrItem`), where all
three variants are used.
- For representing function-like macros (e.g. in `MacCall` and `MacroDef`),
where only the `Delimited` variant is used.
In other words, `MacArgs` is used in two quite different places due to them
having partial overlap. I find this makes the code hard to read. It also leads
to various unreachable code paths, and allows invalid values (such as
accidentally using `MacArgs::Empty` in a `MacCall`).
This commit splits `MacArgs` in two:
- `DelimArgs` is a new struct just for the "delimited arguments" case. It is
now used in `MacCall` and `MacroDef`.
- `AttrArgs` is a renaming of the old `MacArgs` enum for the attribute macro
case. Its `Delimited` variant now contains a `DelimArgs`.
Various other related things are renamed as well.
These changes make the code clearer, avoids several unreachable paths, and
disallows the invalid values.
Support using `Self` or projections inside an RPIT/async fn
I reuse the same idea as https://github.com/rust-lang/rust/pull/103449 to use variances to encode whether a lifetime parameter is captured by impl-trait.
The current implementation of async and RPIT replace all lifetimes from the parent generics by `'static`. This PR changes the scheme
```rust
impl<'a> Foo<'a> {
fn foo<'b, T>() -> impl Into<Self> + 'b { ... }
}
opaque Foo::<'_a>::foo::<'_b, T>::opaque<'b>: Into<Foo<'_a>> + 'b;
impl<'a> Foo<'a> {
// OLD
fn foo<'b, T>() -> Foo::<'static>::foo::<'static, T>::opaque::<'b> { ... }
^^^^^^^ the `Self` becomes `Foo<'static>`
// NEW
fn foo<'b, T>() -> Foo::<'a>::foo::<'b, T>::opaque::<'b> { ... }
^^ the `Self` stays `Foo<'a>`
}
```
There is the same issue with projections. In the example, substitute `Self` by `<T as Trait<'b>>::Assoc` in the sugared version, and `Foo<'_a>` by `<T as Trait<'_b>>::Assoc` in the desugared one.
This allows to support `Self` in impl-trait, since we do not replace lifetimes by `'static` any more. The same trick allows to use projections like `T::Assoc` where `Self` is allowed. The feature is gated behind a `impl_trait_projections` feature gate.
The implementation relies on 2 tweaking rules for opaques in 2 places:
- we only relate substs that correspond to captured lifetimes during TypeRelation;
- we only list captured lifetimes in choice region computation.
For simplicity, I encoded the "capturedness" of lifetimes as a variance, `Bivariant` vs `Invariant` for unused vs captured lifetimes. The `variances_of` query used to ICE for opaques.
Impl-trait that do not reference `Self` or projections will have their variances as:
- `o` (invariant) for each parent type or const;
- `*` (bivariant) for each parent lifetime --> will not participate in borrowck;
- `o` (invariant) for each own lifetime.
Impl-trait that does reference `Self` and/or projections will have some parent lifetimes marked as `o` (as the example above), and participate in type relation and borrowck. In the example above, `variances_of(opaque) = ['_a: o, '_b: *, T: o, 'b: o]`.
r? types
cc `@compiler-errors` , as you asked about the issue with `Self` and projections.
Record `LocalDefId` in HIR nodes instead of a side table
This is part of an attempt to remove the `HirId -> LocalDefId` table from HIR.
This attempt is a prerequisite to creation of `LocalDefId` after HIR lowering (https://github.com/rust-lang/rust/pull/96840), by controlling how `def_id` information is accessed.
This first part adds the information to HIR nodes themselves instead of a table.
The second part is https://github.com/rust-lang/rust/pull/103902
The third part will be to make `hir::Visitor::visit_fn` take a `LocalDefId` as last parameter.
The fourth part will be to completely remove the side table.
Track where diagnostics were created.
This implements the `-Ztrack-diagnostics` flag, which uses `#[track_caller]` to track where diagnostics are created. It is meant as a debugging tool much like `-Ztreat-err-as-bug`.
For example, the following code...
```rust
struct A;
struct B;
fn main(){
let _: A = B;
}
```
...now emits the following error message:
```
error[E0308]: mismatched types
--> src\main.rs:5:16
|
5 | let _: A = B;
| - ^ expected struct `A`, found struct `B`
| |
| expected due to this
-Ztrack-diagnostics: created at compiler\rustc_infer\src\infer\error_reporting\mod.rs:2275:31
```
rustc_metadata: Encode even less doc comments
The fact that `def_id` is in the `tcx.privacy_access_levels(())` table is not very meaningful, especially after https://github.com/rust-lang/rust/pull/102026, `is_exported` (or `is_reachable` in the worst case) is what you need.
Follow up to https://github.com/rust-lang/rust/pull/98450.
r? `@GuillaumeGomez` `@lqd`
The new implementation doesn't use weak lang items and instead changes
`#[alloc_error_handler]` to an attribute macro just like
`#[global_allocator]`.
The attribute will generate the `__rg_oom` function which is called by
the compiler-generated `__rust_alloc_error_handler`. If no `__rg_oom`
function is defined in any crate then the compiler shim will call
`__rdl_oom` in the alloc crate which will simply panic.
This also fixes link errors with `-C link-dead-code` with
`default_alloc_error_handler`: `__rg_oom` was previously defined in the
alloc crate and would attempt to reference the `oom` lang item, even if
it didn't exist. This worked as long as `__rg_oom` was excluded from
linking since it was not called.
This is a prerequisite for the stabilization of
`default_alloc_error_handler` (#102318).
spastorino noticed some silly expressions like `item_id.def_id.def_id`.
This commit renames several `def_id: OwnerId` fields as `owner_id`, so
those expressions become `item_id.owner_id.def_id`.
`item_id.owner_id.local_def_id` would be even clearer, but the use of
`def_id` for values of type `LocalDefId` is *very* widespread, so I left
that alone.
privacy: Rename "accessibility levels" to "effective visibilities"
And a couple of other naming and comment tweaks.
Related to https://github.com/rust-lang/rust/issues/48054
For `enum Level` I initially used naming `enum EffectiveVisibilityLevel`, but it was too long and inconvenient because it's used pretty often.
So I shortened it to just `Level`, if it needs to be used from some context where this name would be ambiguous, then it can be imported with renaming like `use rustc_middle::privacy::Level as EffVisLevel` or something.
rustc_metadata: Add struct and variant constructors to module children at encoding time
instead of decoding time.
Continuation of https://github.com/rust-lang/rust/pull/95899.
The last time it caused some ICEs from generator use, but not everything seems ok.
Rollup of 6 pull requests
Successful merges:
- #101293 (Recover when unclosed char literal is parsed as a lifetime in some positions)
- #101908 (Suggest let for assignment, and some code refactor)
- #103192 (rustdoc: Eliminate uses of `EarlyDocLinkResolver::all_traits`)
- #103226 (Check `needs_infer` before `needs_drop` during HIR generator analysis)
- #103249 (resolve: Revert "Set effective visibilities for imports more precisely")
- #103305 (Move some tests to more reasonable places)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Get rid of native_library projection queries
They don't seem particularly useful as I don't expect native libraries to change frequently.
Maybe they do provide significant value of keeping incremental compilation green though, I'm not sure.
Introduce deduced parameter attributes, and use them for deducing `readonly` on indirect immutable freeze by-value function parameters.
Introduce deduced parameter attributes, and use them for deducing `readonly` on
indirect immutable freeze by-value function parameters.
Right now, `rustc` only examines function signatures and the platform ABI when
determining the LLVM attributes to apply to parameters. This results in missed
optimizations, because there are some attributes that can be determined via
analysis of the MIR making up the function body. In particular, `readonly`
could be applied to most indirectly-passed by-value function arguments
(specifically, those that are freeze and are observed not to be mutated), but
it currently is not.
This patch introduces the machinery that allows `rustc` to determine those
attributes. It consists of a query, `deduced_param_attrs`, that, when
evaluated, analyzes the MIR of the function to determine supplementary
attributes. The results of this query for each function are written into the
crate metadata so that the deduced parameter attributes can be applied to
cross-crate functions. In this patch, we simply check the parameter for
mutations to determine whether the `readonly` attribute should be applied to
parameters that are indirect immutable freeze by-value. More attributes could
conceivably be deduced in the future: `nocapture` and `noalias` come to mind.
Adding `readonly` to indirect function parameters where applicable enables some
potential optimizations in LLVM that are discussed in [issue 103103] and [PR
103070] around avoiding stack-to-stack memory copies that appear in functions
like `core::fmt::Write::write_fmt` and `core::panicking::assert_failed`. These
functions pass a large structure unchanged by value to a subfunction that also
doesn't mutate it. Since the structure in this case is passed as an indirect
parameter, it's a pointer from LLVM's perspective. As a result, the
intermediate copy of the structure that our codegen emits could be optimized
away by LLVM's MemCpyOptimizer if it knew that the pointer is `readonly
nocapture noalias` in both the caller and callee. We already pass `nocapture
noalias`, but we're missing `readonly`, as we can't determine whether a
by-value parameter is mutated by examining the signature in Rust. I didn't have
much success with having LLVM infer the `readonly` attribute, even with fat
LTO; it seems that deducing it at the MIR level is necessary.
No large benefits should be expected from this optimization *now*; LLVM needs
some changes (discussed in [PR 103070]) to more aggressively use the `noalias
nocapture readonly` combination in its alias analysis. I have some LLVM patches
for these optimizations and have had them looked over. With all the patches
applied locally, I enabled LLVM to remove all the `memcpy`s from the following
code:
```rust
fn main() {
println!("Hello {}", 3);
}
```
which is a significant codegen improvement over the status quo. I expect that if this optimization kicks in in multiple places even for such a simple program, then it will apply to Rust code all over the place.
[issue 103103]: https://github.com/rust-lang/rust/issues/103103
[PR 103070]: https://github.com/rust-lang/rust/pull/103070
indirect immutable freeze by-value function parameters.
Right now, `rustc` only examines function signatures and the platform ABI when
determining the LLVM attributes to apply to parameters. This results in missed
optimizations, because there are some attributes that can be determined via
analysis of the MIR making up the function body. In particular, `readonly`
could be applied to most indirectly-passed by-value function arguments
(specifically, those that are freeze and are observed not to be mutated), but
it currently is not.
This patch introduces the machinery that allows `rustc` to determine those
attributes. It consists of a query, `deduced_param_attrs`, that, when
evaluated, analyzes the MIR of the function to determine supplementary
attributes. The results of this query for each function are written into the
crate metadata so that the deduced parameter attributes can be applied to
cross-crate functions. In this patch, we simply check the parameter for
mutations to determine whether the `readonly` attribute should be applied to
parameters that are indirect immutable freeze by-value. More attributes could
conceivably be deduced in the future: `nocapture` and `noalias` come to mind.
Adding `readonly` to indirect function parameters where applicable enables some
potential optimizations in LLVM that are discussed in [issue 103103] and [PR
103070] around avoiding stack-to-stack memory copies that appear in functions
like `core::fmt::Write::write_fmt` and `core::panicking::assert_failed`. These
functions pass a large structure unchanged by value to a subfunction that also
doesn't mutate it. Since the structure in this case is passed as an indirect
parameter, it's a pointer from LLVM's perspective. As a result, the
intermediate copy of the structure that our codegen emits could be optimized
away by LLVM's MemCpyOptimizer if it knew that the pointer is `readonly
nocapture noalias` in both the caller and callee. We already pass `nocapture
noalias`, but we're missing `readonly`, as we can't determine whether a
by-value parameter is mutated by examining the signature in Rust. I didn't have
much success with having LLVM infer the `readonly` attribute, even with fat
LTO; it seems that deducing it at the MIR level is necessary.
No large benefits should be expected from this optimization *now*; LLVM needs
some changes (discussed in [PR 103070]) to more aggressively use the `noalias
nocapture readonly` combination in its alias analysis. I have some LLVM patches
for these optimizations and have had them looked over. With all the patches
applied locally, I enabled LLVM to remove all the `memcpy`s from the following
code:
```rust
fn main() {
println!("Hello {}", 3);
}
```
which is a significant codegen improvement over the status quo. I expect that
if this optimization kicks in in multiple places even for such a simple
program, then it will apply to Rust code all over the place.
[issue 103103]: https://github.com/rust-lang/rust/issues/103103
[PR 103070]: https://github.com/rust-lang/rust/pull/103070
If we fail to locate a native library that we are linking with, it could
be the case the user entered a complete file name like `foo.lib` or
`libfoo.a` when we expect them to simply provide `foo`.
In this situation, we now detect that case and suggest the user only
provide the library name itself.
fix a ui test
use `into`
fix clippy ui test
fix a run-make-fulldeps test
implement `IntoQueryParam<DefId>` for `OwnerId`
use `OwnerId` for more queries
change the type of `ParentOwnerIterator::Item` to `(OwnerId, OwnerNode)`
Move and rename `SessionDiagnostic` & `SessionSubdiagnostic` traits and macros
After PR #101434, we want to:
- [x] Move `SessionDiagnostic` to `rustc_errors`.
- [x] Add `emit_` methods that accept `impl SessionDiagnostic` to `Handler`.
- [x] _(optional)_ Rename trait `SessionDiagnostic` to `DiagnosticHandler`.
- [x] _(optional)_ Rename macro `SessionDiagnostic` to `DiagnosticHandler`.
- [x] Update Rustc Dev Guide and Docs to reflect these changes. https://github.com/rust-lang/rustc-dev-guide/pull/1460
Now I am having build issues getting the compiler to build when trying to rename the macro.
<details>
<summary>See diagnostics errors and context when building.</summary>
```
error: diagnostics should only be created in `SessionDiagnostic`/`AddSubdiagnostic` impls
--> compiler/rustc_attr/src/session_diagnostics.rs:13:10
|
13 | #[derive(DiagnosticHandler)]
| ^^^^^^^^^^^^^^^^^ in this derive macro expansion
|
::: /Users/jhonny/.cargo/registry/src/github.com-1ecc6299db9ec823/synstructure-0.12.6/src/macros.rs:94:9
|
94 | / pub fn $derives(
95 | | i: $crate::macros::TokenStream
96 | | ) -> $crate::macros::TokenStream {
| |________________________________________- in this expansion of `#[derive(DiagnosticHandler)]`
|
note: the lint level is defined here
--> compiler/rustc_attr/src/lib.rs:10:9
|
10 | #![deny(rustc::diagnostic_outside_of_impl)]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```
And also this one:
```
error: diagnostics should only be created in `SessionDiagnostic`/`AddSubdiagnostic` impls
--> compiler/rustc_attr/src/session_diagnostics.rs:213:32
|
213 | let mut diag = handler.struct_span_err_with_code(
| ^^^^^^^^^^^^^^^^^^^^^^^^^
```
> **Note**
> Can't find where this message is coming from, because you can see in [this experimental branch](https://github.com/JhonnyBillM/rust/tree/experimental/trying-to-rename-session-diagnostic-macro) that I updated all errors and diags to say:
> error: diagnostics should only be created in **`DiagnosticHandler`**/`AddSubdiagnostic` impls
> and not:
> error: diagnostics should only be created in **`SessionDiagnostic`**/`AddSubdiagnostic` impls
</details>
I tried building the compiler in different ways (playing with the stages etc), but nothing worked.
## Question
**Do we need to build or do something different when renaming a macro and identifiers?**
For context, see experimental commit f2193a98b4 where the macro and symbols are renamed, but it doesn't compile.
FIX - ambiguous Diagnostic link in docs
UPDATE - rename diagnostic_items to IntoDiagnostic and AddToDiagnostic
[Gardening] FIX - formatting via `x fmt`
FIX - rebase conflicts. NOTE: Confirm wheather or not we want to handle TargetDataLayoutErrorsWrapper this way
DELETE - unneeded allow attributes in Handler method
FIX - broken test
FIX - Rebase conflict
UPDATE - rename residual _SessionDiagnostic and fix LintDiag link
