Speed up NLL with HybridIdxSetBuf.
It's a sparse-when-small but dense-when-large index set that is very
efficient for sets that (a) have few elements, (b) have large
universe_size values, and (c) are cleared frequently. Which makes it
perfect for the `gen_set` and `kill_set` sets used by the new borrow
checker.
This patch reduces `tuple-stress`'s NLL-check time by 40%, and up to 12%
for several other benchmarks. And it halves the max-rss for `keccak`,
and has smaller wins for `inflate` and `clap-rs`.
`HybridIdxSetBuf` is a sparse-when-small but dense-when-large index set
that is very efficient for sets that (a) have few elements, (b) have
large `universe_size` values, and (c) are cleared frequently. Which
makes it perfect for the `gen_set` and `kill_set` sets used by the new
borrow checker.
This patch reduces the execution time of the five slowest NLL benchmarks
by 55%, 21%, 16%, 10% and 9%. It also reduces the max-rss of three
benchmarks by 53%, 33%, and 9%.
optimize redundant borrows and escaping paths in NLL
This builds on https://github.com/rust-lang/rust/pull/53168 and adds a commit that addresses https://github.com/rust-lang/rust/issues/53176 -- or at least I think it does. I marked this as WIP because I want to see the test results (and measure the performance). I also want to double check we're not adding in any unsoundness here.
[NLL] Use span of the closure args in free region errors
Also adds a note when one of the free regions is BrEnv.
In a future PR I'll change these messages to say "return requires", which should improve them a bit more.
r? @nikomatsakis
rustc: Tweak visibility of some lang items
This commit tweaks the linker-level visibility of some lang items that rustc
uses and defines. Notably this means that `#[panic_implementation]` and
`#[alloc_error_handler]` functions are never marked as `internal`. It's up to
the linker to eliminate these, not rustc.
Additionally `#[global_allocator]` generated symbols are no longer forced to
`Default` visibility (fully exported), but rather they're relaxed to `Hidden`
visibility). This symbols are *not* needed across DLL boundaries, only as a
local implementation detail of the compiler-injected allocator symbols, so
`Hidden` should suffice.
Closes#51342Closes#52795
revert #52991
Reverts https://github.com/rust-lang/rust/pull/52991 which is flawed. I have an idea how to fix it but might as well revert first since it is so wildly flawed. That's what I get for opening PRs while on PTO =)
r? @pnkfelix
This commit tweaks the linker-level visibility of some lang items that rustc
uses and defines. Notably this means that `#[panic_implementation]` and
`#[alloc_error_handler]` functions are never marked as `internal`. It's up to
the linker to eliminate these, not rustc.
Additionally `#[global_allocator]` generated symbols are no longer forced to
`Default` visibility (fully exported), but rather they're relaxed to `Hidden`
visibility). This symbols are *not* needed across DLL boundaries, only as a
local implementation detail of the compiler-injected allocator symbols, so
`Hidden` should suffice.
Closes#51342Closes#52795
The previous iteration was a large `match` which was quite heavily indented,
making it slightly difficult to read and see what was going on. This iteration
is a refactoring (no functional change intended) to make it a bit easier on the
eyes and a bit easier to modify over time.
Place unions, pointer casts and pointer derefs behind extra feature gates
To ensure we don't stabilize these things together with const fn stabilization (or any other stabilization)
This PR moves union field accesses inside `const fn` behind a feature gate. It was possible without a feature gate before, but since `const fn` was behind a feature gate we can do this change.
While "dereferencing raw pointers" and "casting raw pointers to usize" were hard errors before this PR, one could work around them by abusing unions:
```rust
// deref
union Foo<T> {
x: &'static T,
y: *const T,
}
const FOO: u32 = unsafe { *Foo { y: 42 as *const T }.x };
// as usize cast
union Bar<T> {
x: usize,
y: *const T,
}
const BAR: usize = unsafe { Bar { y: &1u8 }.x };
```
r? @eddyb
cc @nikomatsakis
