This commit intends to fix an accidental regression from #70846. The
goal of #70846 was to build compiler-builtins with a maximal number of
CGUs to ensure that each module in the source corresponds to an object
file. This high degree of control for compiler-builtins is desirable to
ensure that there's at most one exported symbol per CGU, ideally
enabling compiler-builtins to not conflict with the system libgcc as
often.
In #70846, however, only part of the compiler understands that
compiler-builtins is built with many CGUs. The rest of the compiler
thinks it's building with `sess.codegen_units()`. Notably the
calculation of `sess.lto()` consults `sess.codegen_units()`, which when
there's only one CGU it disables ThinLTO. This means that
compiler-builtins is built without ThinLTO, which is quite harmful to
performance! This is the root of the cause from #73135 where intrinsics
were found to not be inlining trivial functions.
The fix applied in this commit is to remove the special-casing of
compiler-builtins in the compiler. Instead the build system is now
responsible for special-casing compiler-builtins. It doesn't know
exactly how many CGUs will be needed but it passes a large number that
is assumed to be much greater than the number of source-level modules
needed. After reading the various locations in the compiler source, this
seemed like the best solution rather than adding more and more special
casing in the compiler for compiler-builtins.
Closes#73135
Change opt-level from 2 back to 3
In Cargo.toml, the opt-level for `release` and `bench` was overridden to be 2. This was to work around a problem with LLVM 7. However, rust no longer uses LLVM 7, so this is hopefully no longer needed?
I tried a little bit to replicate the original problem, and could not. I think running this through CI is the best way to smoke test this :) Even if things break dramatically, the comment should be updated to reflect that things are still broken with LLVM 9.
I'm just getting started playing with the compiler, so apologies if I've missed an obvious problem here.
fixes#52378
(possibly relevant is the [current update to LLVM 10](https://github.com/rust-lang/rust/pull/67759))
In Cargo.toml, the opt-level for `release` and `bench` was
overridden to be 2. This was to work around a problem with LLVM
7. However, rust no longer uses LLVM 7, so this is no longer
needed.
This creates a small compile time regression in MIR constant eval,
so I've added a #[inline(always)] on the `step` function used in
const eval
Also creates a binary size increase in wasm-stringify-ints-small,
so I've bumped the limit there.
Since its inception rustbuild has always worked in three stages: one for
libstd, one for libtest, and one for rustc. These three stages were
architected around crates.io dependencies, where rustc wants to depend
on crates.io crates but said crates don't explicitly depend on libstd,
requiring a sysroot assembly step in the middle. This same logic was
applied for libtest where libtest wants to depend on crates.io crates
(`getopts`) but `getopts` didn't say that it depended on std, so it
needed `std` built ahead of time.
Lots of time has passed since the inception of rustbuild, however,
and we've since gotten to the point where even `std` itself is depending
on crates.io crates (albeit with some wonky configuration). This
commit applies the same logic to the two dependencies that the `test`
crate pulls in from crates.io, `getopts` and `unicode-width`. Over the
many years since rustbuild's inception `unicode-width` was the only
dependency picked up by the `test` crate, so the extra configuration
necessary to get crates building in this crate graph is unlikely to be
too much of a burden on developers.
After this patch it means that there are now only two build phasese of
rustbuild, one for libstd and one for rustc. The libtest/libproc_macro
build phase is all lumped into one now with `std`.
This was originally motivated by rust-lang/cargo#7216 where Cargo was
having to deal with synthesizing dependency edges but this commit makes
them explicit in this repository.
Changes:
````
Revert "tests: used_underscore_binding_macro: disable random_state lint."
Revert "Auto merge of #3603 - xfix:random-state-lint, r=phansch"
rustup https://github.com/rust-lang/rust/pull/56837
rustup (don't know the exact PR unfortunately)
Add itertools to integration tests
tests: used_underscore_binding_macro: disable random_state lint.
Trigger `use_self` lint in local macros
Add run-rustfix where it already passes
rustup: https://github.com/rust-lang/rust/pull/55517
Make clippy work with parallel rustc
Add ui/for_kv_map test for false positive in #1279
Update to latest compiletest-rs release
add testcase for #3462
deps: bump rustc_tools_util version from 0.1.0 to 0.1.1 just in case...
Use compiletest's aux-build header instead of include macro
rustc_tool_utils: fix failure to create proper non-repo version string when used in crates on crates.io, bump version
rustfmt
UI test cleanup: Extract ifs_same_cond tests
Extract IteratorFalsePositives into option_helpers.rs
UI test cleanup: Extract for_kv_map lint tests
UI test cleanup: Extract lint from methods.rs test
Fix test for rust-lang/rust#57250
Limit infinite_iter collect() check to known types
Some improvements to util documentation
Use hashset for name blacklist
Reformat random_state tests
Use node_id_to_type_opt instead of node_it_to_type in random_state
Check pattern equality while checking declaration equality
random_state lint
Move constant write checks to temporary_assignment lint
Use an FxHashSet for valid idents in documentation lint
Fix suggestion for unnecessary_ref lint
Update CONTRIBUTING.md for rustfix tests
Update .fixed files via update-references.sh
Run rustfix on first UI test
Use WIP branch for compiletest_rs
````
Ever since we added a Cargo-based build system for the compiler the
standard library has always been a little special, it's never been able
to depend on crates.io crates for runtime dependencies. This has been a
result of various limitations, namely that Cargo doesn't understand that
crates from crates.io depend on libcore, so Cargo tries to build crates
before libcore is finished.
I had an idea this afternoon, however, which lifts the strategy
from #52919 to directly depend on crates.io crates from the standard
library. After all is said and done this removes a whopping three
submodules that we need to manage!
The basic idea here is that for any crate `std` depends on it adds an
*optional* dependency on an empty crate on crates.io, in this case named
`rustc-std-workspace-core`. This crate is overridden via `[patch]` in
this repository to point to a local crate we write, and *that* has a
`path` dependency on libcore.
Note that all `no_std` crates also depend on `compiler_builtins`, but if
we're not using submodules we can publish `compiler_builtins` to
crates.io and all crates can depend on it anyway! The basic strategy
then looks like:
* The standard library (or some transitive dep) decides to depend on a
crate `foo`.
* The standard library adds
```toml
[dependencies]
foo = { version = "0.1", features = ['rustc-dep-of-std'] }
```
* The crate `foo` has an optional dependency on `rustc-std-workspace-core`
* The crate `foo` has an optional dependency on `compiler_builtins`
* The crate `foo` has a feature `rustc-dep-of-std` which activates these
crates and any other necessary infrastructure in the crate.
A sample commit for `dlmalloc` [turns out to be quite simple][commit].
After that all `no_std` crates should largely build "as is" and still be
publishable on crates.io! Notably they should be able to continue to use
stable Rust if necessary, since the `rename-dependency` feature of Cargo
is soon stabilizing.
As a proof of concept, this commit removes the `dlmalloc`,
`libcompiler_builtins`, and `libc` submodules from this repository. Long
thorns in our side these are now gone for good and we can directly
depend on crates.io! It's hoped that in the long term we can bring in
other crates as necessary, but for now this is largely intended to
simply make it easier to manage these crates and remove submodules.
This should be a transparent non-breaking change for all users, but one
possible stickler is that this almost for sure breaks out-of-tree
`std`-building tools like `xargo` and `cargo-xbuild`. I think it should
be relatively easy to get them working, however, as all that's needed is
an entry in the `[patch]` section used to build the standard library.
Hopefully we can work with these tools to solve this problem!
[commit]: 28ee12db81
