`GenKillAnalysis` has five methods that take a transfer function arg:
- `statement_effect`
- `before_statement_effect`
- `terminator_effect`
- `before_terminator_effect`
- `call_return_effect`
All the transfer function args have type `&mut impl GenKill<Self::Idx>`,
except for `terminator_effect`, which takes the simpler `Self::Domain`.
But only the first two need to be `impl GenKill`. The other
three can all be `Self::Domain`, just like `Analysis`. So this commit
changes the last two to take `Self::Domain`, making `GenKillAnalysis`
and `Analysis` more similar.
(Another idea would be to make all these methods `impl GenKill`. But
that doesn't work: `MaybeInitializedPlaces::terminator_effect` requires
the arg be `Self::Domain` so that `self_is_unwind_dead(place, state)`
can be called on it.)
They both now only ever contain a `Results<'tcx, A>`.
This means `AnalysisResults` can be removed, as can many
`borrow`/`borrow_mut` calls. Also `Results` no longer needs a
`PhantomData` because `'tcx` is now named by `entry_sets`.
It's only implemented for analyses that implement `Copy`, which means
it's basically a complicated synonym for `Copy`. So this commit removes
it and uses `Copy` directly. (That direct use will be removed in a later
commit.)
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.
