36b495f3cf
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. |
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| Cargo.toml | ||