shared-generics: Do not share instantiations that contain local-only types
In Zed shared-generics loading takes up a significant chunk of time in incremental build, as rustc deserializes rmeta of all dependencies of a crate. I've recently realized that shared-generics includes all instantiations of some_generic_function in the following snippet:
```rs
pub fn some_generic_function(_: impl Fn()) {}
pub fn non_generic_function() {
some_generic_function(|| {});
some_generic_function(|| {});
some_generic_function(|| {});
some_generic_function(|| {});
some_generic_function(|| {});
some_generic_function(|| {});
some_generic_function(|| {});
}
```
even though none of these instantiations can actually be created from outside of `non_generic_function`. This is a dummy example, but we do rely on invoking callbacks with FnOnce a lot in our codebase.
This PR makes shared-generics account for visibilities of generic arguments; an item is only considered for exporting if it is reachable from the outside or if all of it's arguments are visible outside of the local crate.
This PR reduces incremental build time for Zed (touch editor.rs scenario) from 12.4s to 10.4s. I'd love to see a perf run if possible; per my checks this PR does not incur new instantiations in downstream crates, so if there'd be perf regressions, I'd expect them to come from newly-introduced visibility checks.
In Zed shared-generics loading takes up a significant chunk of time in incremental build, as rustc deserializes rmeta of all dependencies of a crate.
I've recently realized that shared-generics includes all instantiations of some_generic_function in the following snippet:
```rs
pub fn some_generic_function(_: impl Fn()) {}
pub fn non_generic_function() {
some_generic_function(|| {});
some_generic_function(|| {});
some_generic_function(|| {});
some_generic_function(|| {});
some_generic_function(|| {});
some_generic_function(|| {});
some_generic_function(|| {});
}
```
even though none of these instantiations can actually be created from outside of `non_generic_function`.
This PR makes shared-generics account for visibilities of generic arguments; an item is only considered for exporting if it is reachable from the outside or if all of it's arguments are visible outside of the local crate.
This PR reduces incremental build time for Zed (touch edito.rs scenario) from 12.4s to 10.4s.
Co-authored-by: bjorn3 <17426603+bjorn3@users.noreply.github.com>
If creating a temporary directory fails with permission denied then retry with backoff
On Windows, if creating a temporary directory fails with permission denied then use a retry/backoff loop. This hopefully fixes a recuring error in our CI.
cc ```@jieyouxu,``` https://github.com/rust-lang/rust/issues/133959
On Windows, if creating a temporary directory fails with permission denied then use a retry/backoff loop. This hopefully fixes a recuring error in our CI.
Rename `is_like_osx` to `is_like_darwin`
Replace `is_like_osx` with `is_like_darwin`, which more closely describes reality (OS X is the pre-2016 name for macOS, and is by now quite outdated; Darwin is the overall name for the OS underlying Apple's macOS, iOS, etc.).
``@rustbot`` label O-apple
r? compiler
Improve `xcrun` error handling
The compiler invokes `xcrun` on macOS when linking Apple targets, to find the Xcode SDK which contain all the necessary linker stubs. The error messages that `xcrun` outputs aren't always that great though, so this PR tries to improve that by providing extra context when an error occurs.
Fixes https://github.com/rust-lang/rust/issues/56829.
Fixes https://github.com/rust-lang/rust/issues/84534.
Part of https://github.com/rust-lang/rust/issues/129432.
See also the alternative https://github.com/rust-lang/rust/pull/131433.
Tested on:
- `x86_64-apple-darwin`, MacBook Pro running Mac OS X 10.12.6
- With no tooling installed
- With Xcode 9.2
- With Xcode 9.2 Commandline Tools
- `aarch64-apple-darwin`, MacBook M2 Pro running macOS 14.7.4
- With Xcode 13.4.1
- With Xcode 16.2
- Inside `nix-shell -p xcbuild` (nixpkgs' `xcrun` shim)
- `aarch64-apple-darwin`, VM running macOS 15.3.1
- With no tooling installed
- With Xcode 16.2 Commandline Tools
``@rustbot`` label O-apple
r? compiler
CC ``@BlackHoleFox`` ``@thomcc``
Remove InstanceKind::generates_cgu_internal_copy
This PR should not contain any behavior changes. Before this PR, the logic for selecting instantiation mode is spread across all of
* `instantiation_mode`
* `cross_crate_inlinable`
* `generates_cgu_internal_copy`
* `requires_inline`
The last two of those functions are not well-designed. The function that actually decides if we generate a CGU-internal copy is `instantiation_mode`, _not_ `generates_cgu_internal_copy`. The function `requires_inline` documents that it is about the LLVM `inline` attribute and that it is a hint. The LLVM attribute is called `inlinehint`, this function is also used by other codegen backends, and since it is part of instantiation mode selection it is *not* a hint.
The goal of this PR is to start cleaning up the logic into a sequence of checks that have a more logical flow and are easier to customize in the future (to do things like improve incrementality or improve optimizations without causing obscure linker errors because you forgot to update another part of the compiler).
Don't attempt to export compiler-builtins symbols from rust dylibs
They are marked with hidden visibility to prevent them from getting exported, so we shouldn't ask the linker to export them anyway. The only thing that does it cause a warning on macOS.
Part of https://github.com/rust-lang/rust/issues/136096
cc `@jyn514`
Avoid no-op unlink+link dances in incr comp
Incremental compilation scales quite poorly with the number of CGUs. This PR improves one reason for that.
The incr comp process hard-links all the files from an old session into a new one, then it runs the backend, which may just hard-link the new session files into the output directory. Then codegen hard-links all the output files back to the new session directory.
This PR (perhaps unimaginatively) fixes the silliness that ensues in the last step. The old `link_or_copy` implementation would be passed pairs of paths which are already the same inode, then it would blindly delete the destination and re-create the hard-link that it just deleted. This PR lets us skip both those operations. We don't skip the other two hard-links.
`cargo +stage1 b && touch crates/core/main.rs && strace -cfw -elink,linkat,unlink,unlinkat cargo +stage1 b` before and then after on `ripgrep-13.0.0`:
```
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
52.56 0.024950 25 978 485 unlink
34.38 0.016318 22 727 linkat
13.06 0.006200 24 249 unlinkat
------ ----------- ----------- --------- --------- ----------------
100.00 0.047467 24 1954 485 total
```
```
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
42.83 0.014521 57 252 unlink
38.41 0.013021 26 486 linkat
18.77 0.006362 25 249 unlinkat
------ ----------- ----------- --------- --------- ----------------
100.00 0.033904 34 987 total
```
This reduces the number of hard-links that are causing perf troubles, noted in https://github.com/rust-lang/rust/issues/64291 and https://github.com/rust-lang/rust/issues/137560
They are marked with hidden visibility to prevent them from getting
exported, so we shouldn't ask the linker to export them anyway. The only
thing that does it cause a warning on macOS.
Rollup of 7 pull requests
Successful merges:
- #138384 (Move `hir::Item::ident` into `hir::ItemKind`.)
- #138508 (Clarify "owned data" in E0515.md)
- #138531 (Store test diffs in job summaries and improve analysis formatting)
- #138533 (Only use `DIST_TRY_BUILD` for try jobs that were not selected explicitly)
- #138556 (Fix ICE: attempted to remap an already remapped filename)
- #138608 (rustc_target: Add target feature constraints for LoongArch)
- #138619 (Flatten `if`s in `rustc_codegen_ssa`)
r? `@ghost`
`@rustbot` modify labels: rollup
Mangle rustc_std_internal_symbols functions
This reduces the risk of issues when using a staticlib or rust dylib compiled with a different rustc version in a rust program. Currently this will either (in the case of staticlib) cause a linker error due to duplicate symbol definitions, or (in the case of rust dylibs) cause rustc_std_internal_symbols functions to be silently overridden. As rust gets more commonly used inside the implementation of libraries consumed with a C interface (like Spidermonkey, Ruby YJIT (curently has to do partial linking of all rust code to hide all symbols not part of the C api), the Rusticl OpenCL implementation in mesa) this is becoming much more of an issue. With this PR the only symbols remaining with an unmangled name are rust_eh_personality (LLVM doesn't allow renaming it) and `__rust_no_alloc_shim_is_unstable`.
Helps mitigate https://github.com/rust-lang/rust/issues/104707
try-job: aarch64-gnu-debug
try-job: aarch64-apple
try-job: x86_64-apple-1
try-job: x86_64-mingw-1
try-job: i686-mingw-1
try-job: x86_64-msvc-1
try-job: i686-msvc-1
try-job: test-various
try-job: armhf-gnu
Denote `ControlFlow` as `#[must_use]`
I've repeatedly hit bugs in the compiler due to `ControlFlow` not being marked `#[must_use]`. There seems to be an accepted ACP to make the type `#[must_use]` (https://github.com/rust-lang/libs-team/issues/444), so this PR implements that part of it.
Most of the usages in the compiler that trigger this new warning are "root" usages (calling into an API that uses control-flow internally, but for which the callee doesn't really care) and have been suppressed by `let _ = ...`, but I did legitimately find one instance of a missing `?` and one for a never-used `ControlFlow` value in #137448.
Presumably this needs an FCP too, so I'm opening this and nominating it for T-libs-api.
This PR also touches the tools (incl. rust-analyzer), but if this went into FCP, I'd split those out into separate PRs which can land before this one does.
r? libs-api
`@rustbot` label: T-libs-api I-libs-api-nominated
On Unix the limits can be gargantuan anyway so we're pretty
unlikely to hit them, but might still exceed it.
We consult ARG_MAX here to get an estimate.
fix: remove the check of lld not supporting @response-file
In LLVM v9, lld has supported `@response-file.`
LLVM v9 was released on 2019-09-19.
The check was added back to 2018-03-14 (1.26.0) via 04442af18b.
It has been more than five years, and we ship our own lld regardlessly.
This should be happily removed.
See also:
* <bb12396f91>
* <https://reviews.llvm.org/D63024>
metadata: Ignore sysroot when doing the manual native lib search in rustc
This is the opposite alternative to https://github.com/rust-lang/rust/pull/138170 and another way to make native library search consistent between rustc and linker.
This way the directory list searched by rustc is still a prefix of the directory list considered by linker, but it's a shorter prefix than in #138170.
We can include the sysroot directories into rustc's search again later if the issues with #138170 are resolved, it will be a backward compatible change.
This may break some code doing weird things on unstable rustc, or tier 2-3 targets, like bundling `libunwind.a` or sanitizers into something.
Note that this doesn't affect shipped `libc.a`, because it lives in `self-contained` directories in sysroot, and `self-contained` sysroot is already not included into the rustc's search. All libunwind and sanitizer libs should be moved to `self-contained` sysroot too eventually.
With the consistent search directory list between rustc and linker we can make rustc own the native library search (at least for static libs) and use linker search only as a fallback (like in #123436). This will allow addressing issues like https://github.com/rust-lang/rust/pull/132394 once and for all on all targets.
r? ``@bjorn3``
In LLVM v9, lld has supported @response-file
LLVM v9 was released on 2019-09-19.
And the check was added back to 2018-03-14 (1.26.0) via 04442af18b.
It has been more than five years, and we ship our own lld regardlessly.
This should be happily removed.
See also:
* <bb12396f91>
* <https://reviews.llvm.org/D63024>
Continuing the work from #137350.
Removes the unused methods: `expect_variant`, `expect_field`,
`expect_foreign_item`.
Every method gains a `hir_` prefix.
compiler: Use `size_of` from the prelude instead of imported
Use `std::mem::{size_of, size_of_val, align_of, align_of_val}` from the prelude instead of importing or qualifying them. Apply this change across the compiler.
These functions were added to all preludes in Rust 1.80.
r? ``@compiler-errors``
self-contained linker: conservatively default to `-znostart-stop-gc` on x64 linux
To help stabilization, this PR disables an LLD optimization on x64 linux with respect to `--gc-sections` and encapsulation symbols: it will reduce the number of crates needing to opt-out of lld due to this bfd / lld difference. For example, all the people using [linkme](https://github.com/dtolnay/linkme), which [doesn't work with lld](https://github.com/dtolnay/linkme/issues/63) or on nightly, need to disable lld.
More information about all this, and the historical differences, can be found in:
- https://maskray.me/blog/2021-01-31-metadata-sections-comdat-and-shf-link-order
- https://lld.llvm.org/ELF/start-stop-gc
This optimization has [no visible impact](https://github.com/rust-lang/rust/pull/137685#issuecomment-2686116312) on our benchmarks, so we can use it by default and have a safer/more conservative starting point to remove friction during migration. We can them emit an FCW for the cases where lld detects reliance on encapsulation symbols without `-znostart-stop-gc`, and then revert back to lld's default after a while. No one compiling on nightly relies on this difference, obviously, so doing an FCW is not necessary until after lld is used on stable.
I've tested that this correctly links on `linkme` examples. I've also quickly tried to crate an rmake test but the setup with encapsulation symbols is annoying to reproduce: a few link section/name attributes is not enough, we also need to collect symbols between the encapsulation symbols, without referencing them in code, for `-znostart-stop-gc` to only impact this... It should of course be doable though, maybe ````@Kobzol```` will look into it if they have time.
r? ````@petrochenkov````
