MatchBranchSimplification: fix equal const bool assignments
The match branch simplification is applied when target blocks contain
statements that are either equal or perform a const bool assignment with
different values to the same place.
Previously, when constructing new statements, only statements from a
single block had been examined. This lead to a misoptimization when
statements are equal because the assign the *same* const bool value to
the same place.
Fix the issue by examining statements from both blocks when deciding on
replacement.
Additionally:
* Copy discriminant instead of moving it since it might be necessary to use its
value more than once.
* Optimize when switching on copy operand
Based on #75508.
r? @oli-obk / @JulianKnodt
Add sanitizer support on FreeBSD
Restarting #47337. Everything is better now, no more weird llvm problems, well not everything:
Unfortunately, the sanitizers don't have proper support for versioned symbols (https://github.com/google/sanitizers/issues/628), so `libc`'s usage of `stat@FBSD_1.0` and so on explodes, e.g. in calling `std::fs::metadata`.
Building std (now easy thanks to cargo `-Zbuild-std`) and libc with `freebsd12/13` config via the `LIBC_CI=1` env variable is a good workaround…
```
LIBC_CI=1 RUSTFLAGS="-Z sanitizer=address" cargo +san-test -Zbuild-std run --target x86_64-unknown-freebsd --verbose
```
…*except* std won't build because there's no `st_lspare` in the ino64 version of the struct, so an std patch is required:
```diff
--- i/src/libstd/os/freebsd/fs.rs
+++ w/src/libstd/os/freebsd/fs.rs
@@ -66,8 +66,6 @@ pub trait MetadataExt {
fn st_flags(&self) -> u32;
#[stable(feature = "metadata_ext2", since = "1.8.0")]
fn st_gen(&self) -> u32;
- #[stable(feature = "metadata_ext2", since = "1.8.0")]
- fn st_lspare(&self) -> u32;
}
#[stable(feature = "metadata_ext", since = "1.1.0")]
@@ -136,7 +134,4 @@ impl MetadataExt for Metadata {
fn st_flags(&self) -> u32 {
self.as_inner().as_inner().st_flags as u32
}
- fn st_lspare(&self) -> u32 {
- self.as_inner().as_inner().st_lspare as u32
- }
}
```
I guess std could like.. detect that `libc` isn't built for the old ABI, and replace the implementation of `st_lspare` with a panic?
Previously it was listed as a package but wasn't available in the component
lists in rustup, so wasn't actually installable.
rustc-docs is also only present for x86_64-unknown-linux-gnu. Eventually it'll
also be shipped for aarch64-gnu with current CI configuration, but that builder
isn't quite up and running yet.
We probably want to ship compiler docs for other platforms as well, though, but
this commit doesn't enable that quite yet. A future PR may do so by adding
--enable-compiler-docs to the relevant builders (but it would also need to
decide the set of builders which we'd ship on).
polymorphize: `I` used if `T` used in `I: Foo<T>`
Fixes#75326.
This PR adjusts polymorphization's handling of predicates so that after ensuring that `T` is used in `I: Foo<T>` if `I` is used, it now ensures that `I` is used if `T` is used in `I: Foo<T>`. This is necessary to mark generic parameters that only exist in impl parameters as used - thereby avoiding symbol clashes when using the new mangling scheme.
With this PR, rustc will now fully bootstrap with polymorphization and the new symbol mangling scheme enabled - not all tests pass, but I'm not sure how much of that is the interaction of the two features, I'll be looking into that soon. All tests pass with only polymorphization enabled.
r? @lcnr (this isn't sufficiently complex that I need to add to eddy's review queue)
cc @eddyb
Fix crate-version with rustdoc in bootstrap.
Cargo will now automatically use the `--crate-version` flag (see https://github.com/rust-lang/cargo/pull/8509). Cargo has special handling to avoid passing the flag if it is passed in via RUSTDOCFLAGS, but the `rustdoc` wrapper circumvents that check. This causes a problem because rustdoc will fail if the flag is passed in twice. Fix this by using RUSTDOCFLAGS.
This will be necessary when 1.47 is promoted to beta, but should be safe to do now.
Revert the fundamental changes in #74762 and #75257
Before possibly going over to #75487. Also contains some added and fixed comments.
r? @Mark-Simulacrum
std/sys/unix/time: make it easier for LLVM to optimize `Instant` subtraction.
This PR is the minimal change necessary to get LLVM to optimize `if self.t.tv_nsec >= other.t.tv_nsec` to branchless instructions (at least on x86_64), inspired by @m-ou-se's own attempts at optimizing `Instant` subtraction.
I stumbled over this by looking at the total number of instructions executed by `rustc -Z self-profile`, and found that after disabling ASLR, the largest source of non-determinism remaining was from this `if` taking one branch or the other, depending on the values involved.
The reason this code is even called so many times to make a difference, is that `measureme` (the `-Z self-profile` implementation) currently uses `Instant::elapsed` for its event timestamps (of which there can be millions).
I doubt it's critical to land this, although perhaps it could slightly improve some forms of benchmarking.
Recover gracefully from `struct` parse errors
Currently the parser tries to recover from finding a keyword where a field name was expected, but this causes extra knock down parse errors that are completely irrelevant. Instead, bail out early in the parsing of the field and consume the remaining tokens in the block. This can reduce output significantly.
_Improvements based on the narrative in https://fasterthanli.me/articles/i-am-a-java-csharp-c-or-cplusplus-dev-time-to-do-some-rust_
merge `as_local_hir_id` with `local_def_id_to_hir_id`
`as_local_hir_id` was defined as just calling `local_def_id_to_hir_id` and I think that having two different ways to call the same method is somewhat confusing.
Don't really care about which of these 2 methods we want to keep.
Does this require an MCP, considering that these methods are fairly frequently used?
Set CMAKE_SYSTEM_NAME when cross-compiling
Configure CMAKE_SYSTEM_NAME when cross-compiling in `configure_cmake`,
to tell CMake about target system. Previously this was done only for
LLVM step and now applies more generally to steps using cmake.
Helps with #74576.
Remove most specialization use in serialization
Switching from specialization to min_specialization in the compiler made the unsoundness of how we used these traits pretty clear. This changes how the `Encodable` and `Decodable` traits work to be more friendly for types need a `TyCtxt` to deserialize.
The alternative design of having both `Encodable` and `TyEncodable` traits was considered, but doesn't really work because the following impls would conflict:
```
impl<E: Ecodable> TyEncodable for Encodable
impl<E: TyEcodable> TyEncodable for [E]
```
## How-to guide
- `Rustc(De|En)codable` is now spelled `Ty(De|En)coable` in `rustc_middle`, `Metadata(En|De)codable` in `rustc_metadata` where needed, and `(De|En)codable` everywhere else.
- Manual implementations of `(De|En)codable` shouldn't be much different.
- If you're adding a new interned type that needs to be en/decodable then the simplest thing way to handle this is:
- Have the type be a wrapper around a reference to the interned data (i.e. do what `ty::Predicate` does, and not what all of the other interned types do)
- Derive `Ty(En|De)codable` on the inner type
- Implement `Encodable<impl TyEncoder>` by forwarding to the inner type.
- Implement `Decodable<impl TyDecoder>` by decoding the inner type and then creating the wrapper around that (using the `tcx` from the decoder as needed).
cc @rust-lang/compiler for opinions on this change
r? @oli-obk
The match branch simplification is applied when target blocks contain
statements that are either equal or perform a const bool assignment with
different values to the same place.
Previously, when constructing new statements, only statements from a
single block had been examined. This lead to a misoptimization when
statements are equal because the assign the *same* const bool value to
the same place.
Fix the issue by examining statements from both blocks when deciding on
replacement.
Rollup of 17 pull requests
Successful merges:
- #73943 (Document the unsafe keyword)
- #74062 (deny(unsafe_op_in_unsafe_fn) in libstd/ffi/c_str.rs)
- #74185 (Remove liballoc unneeded explicit link)
- #74192 (Improve documentation on process::Child.std* fields)
- #74409 (Change Debug impl of SocketAddr and IpAddr to match their Display output)
- #75195 (BTreeMap: purge innocent use of into_kv_mut)
- #75214 (Use intra-doc links in `mem::manually_drop` & `mem::maybe_uninit`)
- #75432 (Switch to intra-doc links in `std::process`)
- #75482 (Clean up E0752 explanation)
- #75501 (Move to intra doc links in std::ffi)
- #75509 (Tweak suggestion for `this` -> `self`)
- #75511 (Do not emit E0228 when it is implied by E0106)
- #75515 (Bump std's libc version to 0.2.74)
- #75517 (Promotion and const interning comments)
- #75519 (BTreeMap: refactor splitpoint and move testing over to unit test)
- #75530 (Switch to intra-doc links in os/raw/*.md)
- #75531 (Migrate unit tests of btree collections to their native breeding ground)
Failed merges:
r? @ghost
This commit adjusts polymorphization's handling of predicates so that
after ensuring that `T` is used in `I: Foo<T>` if `I` is used, it now
ensures that `I` is used if `T` is used in `I: Foo<T>`. This is
necessary to mark generic parameters that only exist in impl parameters
as used - thereby avoiding symbol clashes when using the new mangling
scheme.
Signed-off-by: David Wood <david@davidtw.co>
Migrate unit tests of btree collections to their native breeding ground
There's one BTreeSet test case that I couldn't easily convince to come along, maybe because it truly is an integration test. But leaving it in place would mean git wouldn't see the move so I also moved it to a new file.
r? @Mark-Simulacrum
Do not emit E0228 when it is implied by E0106
Emit E0288 (lifetime bound for trait object cannot be deduced) only on bare trait objects. When the trait object is in the form of `&dyn Trait`, E0106 (missing lifetime specifier) will have been emitted, making the former redundant.
BTreeMap: purge innocent use of into_kv_mut
Replace the use of `into_kv_mut` into more precise calls. This makes more sense if you know that the single remaining use of `into_kv_mut` is in fact evil and can be trialled in court (#75200) and sent to a correction facility (#73971).
No real performance difference reported (but functions that might benefit a tiny constant bit like `BTreeMap::get_mut` aren't benchmarked):
```
benchcmp old new --threshold 5
name old ns/iter new ns/iter diff ns/iter diff % speedup
btree::map::clone_fat_100 63,073 59,256 -3,817 -6.05% x 1.06
btree::map::iter_100 3,514 3,235 -279 -7.94% x 1.09
```
Change Debug impl of SocketAddr and IpAddr to match their Display output
This has already been done for `SocketAddrV4`, `SocketAddrV6`, `IpAddrV4` and `IpAddrV6`. I don't see a point to keep the rather bad to read derived impl, especially so when pretty printing:
V4(
127.0.0.1
)
From the `Display`, one can easily and unambiguously see if it's V4 or V6. Two examples:
```
127.0.0.1:443
[2001:db8:85a3::8a2e:370:7334]:443
```
Luckily the docs explicitly state that `Debug` output is not stable and that it may be changed at any time.
Using `Display` as `Debug` is very convenient for configuration structs (e.g. for webservers) that often just have a `derive(Debug)` and are printed that way to the one starting the server.
Improve documentation on process::Child.std* fields
As a relative beginner, it took a while for me to figure out I could just steal the references to avoid partially moving the child and thus retain ability to call functions on it (and store it in structs etc).
Document the unsafe keyword
Partial fix of #34601 (just one more and it will be done 😄).
I tried to be concise and redirect as much as possible on other, longer resources, exposing only the strict necessary.
I also used `SAFETY:` comments to promote good documentation.
I would like a thorough review to ensure I did not introduce mistakes that would confuse people or worse, lead them to write unsound code.
@rustbot modify labels: T-doc,C-enhancement
Edit: this is now the last PR for the original issue: fixes#34601.
