Remove unneeded `drop_in_place` calls
Might as well pull this out from rust-lang/rust#144561 because this is still used in things like `Vec::truncate` where it'd be nice to allow it be removed if inlined enough to see that the type is `Copy`.
So long as perf says it's ok, at least 🤞
lower pattern bindings in the order they're written and base drop order on primary bindings' order
To fixrust-lang/rust#142163, this PR does two things:
- Makes match arms base their drop order on the first sub-branch instead of the last sub-branch. Together with the second change, this makes bindings' drop order correspond to the relative order of when each binding first appears (i.e. the order of the "primary" bindings).
- Lowers pattern bindings in the order they're written (still treating the right-hand side of a ``@`` as coming before the binding on the left). In each sub-branch of a match arm, this is the order that would be obtained if the or-alternatives chosen in that sub-branch were inlined into the arm's pattern. This both affects drop order (making bindings in or-patterns not be dropped first) and fixes the issue in [this test](https://github.com/rust-lang/rust/blob/2a023bf80a6fbd6a06d5460a34eb247b986286ed/tests/ui/pattern/bindings-after-at/bind-by-copy-or-pat.rs) from rust-lang/rust#121716.
My approach to the second point is admittedly a bit trickier than may be necessary. To avoid passing around a counter when building `FlatPat`s, I've instead added just enough information to recover the original structure of the pattern's bindings from a `MatchTreeSubBranch`'s path through the `Candidate` tree. Some alternatives:
- We could use a counter, then sort bindings by their ordinals when making `MatchTreeSubBranch`es.
- I'd like to experiment with always merging sub-candidates and removing `test_remaining_match_pairs_after_or`; that would require lowering bindings and guards in a different way. That makes it a bigger change too, though, so I figure it might be simplest to start here.
- For a very big change, we could track which or-alternatives succeed at runtime to base drop order on the binding order in the particular alternatives matched.
This is a breaking change. It will need a crater run, language team sign-off, and likely updates to the Reference.
This will conflict with rust-lang/rust#143376 and probably also rust-lang/rust#143028, so they shouldn't be merged at the same time.
r? `@matthewjasper` or `@Nadrieril`
emit `StorageLive` and schedule `StorageDead` for `let`-`else`'s bindings after matching
This PR removes special handling of `let`-`else`, so that `StorageLive`s are emitted and `StorageDead`s are scheduled only after pattern-matching has succeeded. This means `StorageDead`s will no longer appear for all of its bindings on the `else` branch (because they're not live yet) and its drops&`StorageDead`s will happen together like they do elsewhere, rather than having all drops first, then all `StorageDead`s.
This fixesrust-lang/rust#142056, and is therefore a breaking change. I believe it'll need a crater run and a T-lang nomination/fcp thereafter. Specifically, this makes drop-checking slightly more restrictive for `let`-`else` to match the behavior of other variable binding forms. An alternative approach could be to change the relative order of drops and `StorageDead`s for other binding forms to make drop-checking more permissive, but making that consistent would be a significantly more involved change.
r? mir
cc `````@dingxiangfei2009`````
`````@rustbot````` label +T-lang +needs-crater
Add some pre-codegen MIR tests for debug mode
No functional changes; just some tests.
I made these for rust-lang/rust#144483, but that's going in a different direction, so I wanted to propose we just add them to help see the impact of other related changes in the future.
r? mir
`AlignmentEnum` should just be `repr(usize)` now
These used to use specific sizes because they were compiled on all widths. But now that the types themselves are `#[cfg]`'d, we can save some conversions by having it always be `repr(usize)`.
Rollup of 3 pull requests
Successful merges:
- rust-lang/rust#144657 (fix: Only "close the window" when its the last annotated file)
- rust-lang/rust#144665 (Re-block SRoA on SIMD types)
- rust-lang/rust#144713 (`rustc_middle::ty` cleanups)
r? `@ghost`
`@rustbot` modify labels: rollup
coverage: Re-land "Enlarge empty spans during MIR instrumentation"
This allows us to assume that coverage spans will only be discarded during codegen in very unusual situations.
---
This seemingly-simple change has a rather messy history:
- rust-lang/rust#140847
- rust-lang/rust#141650
- rust-lang/rust#144298
- rust-lang/rust#144480
Since then, a number of related changes have landed that should make it reasonable to try again:
- rust-lang/rust#144530
- rust-lang/rust#144560
- rust-lang/rust#144616
In particular, we have multiple fixes/mitigations, and a confirmed regression test for the original bug that is not triggered by re-landing the changes in this PR.
Fix Box allocator drop elaboration
New version of rust-lang/rust#131146.
Clearing Box's drop flag after running its destructor can cause it to skip dropping its allocator, so just don't. Its cleared by the drop ladder code afterwards already.
Unlike the last PR this also handles other types with destructors properly, in the event that we can have open drops on them in the future (by partial initialization or DerefMove or something).
Finally, I also added tests for the interaction with async drop here but I discovered rust-lang/rust#143658, so one of the tests has a `knownbug` annotation. Not sure if it should be in this PR at all though.
Fixesrust-lang/rust#131082
r? wesleywiser - prev. reviewer
MIR-build: No longer emit assumes in enum-as casting
This just uses the `valid_range` from the backend, so it's duplicating the range metadata that now we include on parameters and loads, and thus no longer seems to be useful -- notably there's no codegen test failures from removing it.
(Because it's using data from the same source as the backend annotations, it doesn't do anything to mitigate things like rust-lang/rust#144388 where the range in the layout is more permissive than the actual possible discriminants. A variant of this that actually checked the discriminants more specifically might be useful, so could potentially be added in future, but I don't think the *current* checks are actually providing value.)
r? mir
Randomly turns out that this
Fixes https://github.com/rust-lang/rust/issues/121097
Store the type of each GVN value
MIR is fully typed, so type information is an integral part of what defines a value. GVN currently tries to circumvent storing types, which creates all sorts of complexities.
This PR stores the type along with the enum `Value` when defining a value index. This allows to simplify a lot of code.
Fixesrust-lang/rust#128094Fixesrust-lang/rust#135128
r? ``````@ghost`````` for perf
Only inherit local hash for paths
`DefPathHash`, as the counterpart of `DefId` that is stable across compiler invocations, is comprised of 2 parts. The first one is the `StableCrateId`, stable form of `CrateNum`. The second is 64 complementary bits to identify the crate-local definition.
The current implementation always hashes the full 128 bits when (1) trying to create a new child `DefPathHash` or (2) hashing a `CrateNum` or a `LocalDefId`. But we only need half that information: `LocalDefId` means that the `StableCrateId` is always the current crate's ; `CrateNum` means that we do not care about the local part.
As stable hashing is very hot in the query system, in particular hashing definitions, this is a big deal.
We still want the local part to change when the `StableCrateId` changes, to make incr-compilation errors less painful, ie. increase the likelihood that if will magically disappear by changing some code.
This PR sprinkles some `#[inline]` attributes on small functions that appeared in profiles.
Apply effects to `otherwise` edge in dataflow analysis
This allows `ElaborateDrops` to remove drops when a `match` wildcard arm covers multiple no-Drop enum variants. It modifies dataflow analysis to update the `MaybeUninitializedPlaces` and `MaybeInitializedPlaces` data for a block reached through an `otherwise` edge.
Fixesrust-lang/rust#142705.
Dont resolve instance of root in `mir_callgraph_cyclic`
`Instance::try_resolve` on a default trait body method will always fail, since it's still possible to further substitute. This leads to a cycle, since in `tests/mir-opt/inline_default_trait_body.rs`, both `Trait::a` and `Trait::b` need to consider the other to be cyclical, but since we couldn't resolve a body, we'd just consider *nothing* to be cyclical.
The root instance we care about when computing `mir_callgraph_cyclic` is trivial to compute (it's just `InstanceKind::Item`), so just replace it with a call to `Instance::new_raw`.
r? `@cjgillot` `@oli-obk`
Fixesrust-lang/rust#143534
Stuart Cook