This is similar to the existing `union`, except that bits in the RHS are
negated before being incorporated into the LHS.
Currently only `DenseBitSet` is supported. Supporting other bitset types is
possible, but non-trivial, and currently isn't needed.
A `ChunkedBitSet` has to be at least 2048 bits for it to outperform a
`BitSet`, because that's the chunk size. The largest `SparseBitMatrix`
encountered when compiling the compiler and the entire rustc-perf
benchmark suite is less than 600 bits.
This change is a tiny perf win, but the motivation is more about
avoiding uses of `ChunkedBitSet` outside of `MixedBitSet`.
The test change is necessary to avoid hitting the `<BitSet<T> as
BitRelations<ChunkedBitSet<T>>>::subtract` method that has
`unimplemented!` in its body and isn't otherwise used.
It just uses `BitSet` for small/medium sizes (<= 2048 bits) and
`ChunkedBitSet` for larger sizes. This is good because `ChunkedBitSet`
is slow and memory-hungry at smaller sizes.
The current implementation is slow because it does an operation for
every bit in the set, even zero bits. So if you have a large bitset with
many zero bits (which is common) it's very slow.
This commit improves the iterator to skip over `Zeros` chunks in a
single step, and uses the fast `BitIter` for `Mixed` chunks. It also
removes the existing `fold` implementation, which was only there because
the old iterator was slow.
- Fix a typo in a comment.
- Remove unnecessary `Chunk::` qualifiers.
- Rename `ChunkedBitIter::bitset` as `ChunkedBitIter::bit_set`, because
`bit_set` is the form used everywhere else.
- Avoid some unnecessary local variables.
`ChunkedBitSet::is_empty` currently does an unnecessary check. This
commit removes that check and adds clarifying comments and an assertion
that demonstrate why it's unnecessary.
take 2
open up coroutines
tweak the wordings
the lint works up until 2021
We were missing one case, for ADTs, which was
causing `Result` to yield incorrect results.
only include field spans with significant types
deduplicate and eliminate field spans
switch to emit spans to impl Drops
Co-authored-by: Niko Matsakis <nikomat@amazon.com>
collect drops instead of taking liveness diff
apply some suggestions and add explantory notes
small fix on the cache
let the query recurse through coroutine
new suggestion format with extracted variable name
fine-tune the drop span and messages
bugfix on runtime borrows
tweak message wording
filter out ecosystem types earlier
apply suggestions
clippy
check lint level at session level
further restrict applicability of the lint
translate bid into nop for stable mir
detect cycle in type structure
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).
The previous implementation incorrectly assumed that the
number of words in a bit set is equal to the domain size.
The new implementation delegates to `Vec::clone_from` which
is specialized for `Copy` elements.
Remove dereferencing of Box from codegen
Through #94043, #94414, #94873, and #95328, I've been fixing issues caused by Box being treated like a pointer when it is not a pointer. However, these PRs just introduced special cases for Box. This PR removes those special cases and instead transforms a deref of Box into a deref of the pointer it contains.
Hopefully, this is the end of the Box<T, A> ICEs.
This reduces peak memory usage significantly for some programs with very
large functions, such as:
- `keccak`, `unicode_normalization`, and `match-stress-enum`, from
the `rustc-perf` benchmark suite;
- `http-0.2.6` from crates.io.
The new type is used in the analyses where the bitsets can get huge
(e.g. 10s of thousands of bits): `MaybeInitializedPlaces`,
`MaybeUninitializedPlaces`, and `EverInitializedPlaces`.
Some refactoring was required in `rustc_mir_dataflow`. All existing
analysis domains are either `BitSet` or a trivial wrapper around
`BitSet`, and access in a few places is done via `Borrow<BitSet>` or
`BorrowMut<BitSet>`. Now that some of these domains are `ClusterBitSet`,
that no longer works. So this commit replaces the `Borrow`/`BorrowMut`
usage with a new trait `BitSetExt` containing the needed bitset
operations. The impls just forward these to the underlying bitset type.
This required fiddling with trait bounds in a few places.
The commit also:
- Moves `static_assert_size` from `rustc_data_structures` to
`rustc_index` so it can be used in the latter; the former now
re-exports it so existing users are unaffected.
- Factors out some common "clear excess bits in the final word"
functionality in `bit_set.rs`.
- Uses `fill` in a few places instead of loops.
