The new git submodule src/llvm-project is a monorepo replacing src/llvm
and src/tools/{clang,lld,lldb}. This also serves as a rebase for these
projects to the new 8.x branch from trunk.
The src/llvm-emscripten fork is unchanged for now.
This commit switches the standard library to using the `backtrace-sys`
crate from crates.io instead of duplicating the logic here in the Rust
repositor with the `backtrace-sys`'s crate's logic.
Eventually this will hopefully be a good step towards using the
`backtrace` crate directly from crates.io itself, but we're not quite
there yet! Hopefully this is a small incremental first step we can take.
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
This commit removes all jemalloc related submodules, configuration, etc,
from the bootstrap, from the standard library, and from the compiler.
This will be followed up with a change to use jemalloc specifically as
part of rustc on blessed platforms.
Fixes a problem where submodules could not be cloned under some git
configurations. Specifically, when url.git@github.com:.insteadOf =
https://github.com/ is set.
commit 6c10142251 ("Update LLVM submodule") disabled the lldb build.
This patch updates the lldb and clang submodules to once again build
against the LLVM that is included in the Rust tree, and reverts the
.travis.yml changes from that patch.
This optionally adds lldb (and clang, which it needs) to the build.
Because rust uses LLVM 7, and because clang 7 is not yet released, a
recent git master version of clang is used.
The lldb that is used includes the Rust plugin.
lldb is only built when asked for, or when doing a nightly build on
macOS. Only macOS is done for now due to difficulties with the Python
dependency.
While we're at it update the `backtrace` crate from crates.io. It turns out that
the submodule's configure script has gotten a lot more finnicky as of late so
also switch over to using the `cc` crate manually which allows to avoid some
hacks around the configure script as well
This commit imports the LLD project from LLVM to serve as the default linker for
the `wasm32-unknown-unknown` target. The `binaryen` submoule is consequently
removed along with "binaryen linker" support in rustc.
Moving to LLD brings with it a number of benefits for wasm code:
* LLD is itself an actual linker, so there's no need to compile all wasm code
with LTO any more. As a result builds should be *much* speedier as LTO is no
longer forcibly enabled for all builds of the wasm target.
* LLD is quickly becoming an "official solution" for linking wasm code together.
This, I believe at least, is intended to be the main supported linker for
native code and wasm moving forward. Picking up support early on should help
ensure that we can help LLD identify bugs and otherwise prove that it works
great for all our use cases!
* Improvements to the wasm toolchain are currently primarily focused around LLVM
and LLD (from what I can tell at least), so it's in general much better to be
on this bandwagon for bugfixes and new features.
* Historical "hacks" like `wasm-gc` will soon no longer be necessary, LLD
will [natively implement][gc] `--gc-sections` (better than `wasm-gc`!) which
means a postprocessor is no longer needed to show off Rust's "small wasm
binary size".
LLD is added in a pretty standard way to rustc right now. A new rustbuild target
was defined for building LLD, and this is executed when a compiler's sysroot is
being assembled. LLD is compiled against the LLVM that we've got in tree, which
means we're currently on the `release_60` branch, but this may get upgraded in
the near future!
LLD is placed into rustc's sysroot in a `bin` directory. This is similar to
where `gcc.exe` can be found on Windows. This directory is automatically added
to `PATH` whenever rustc executes the linker, allowing us to define a `WasmLd`
linker which implements the interface that `wasm-ld`, LLD's frontend, expects.
Like Emscripten the LLD target is currently only enabled for Tier 1 platforms,
notably OSX/Windows/Linux, and will need to be installed manually for compiling
to wasm on other platforms. LLD is by default turned off in rustbuild, and
requires a `config.toml` option to be enabled to turn it on.
Finally the unstable `#![wasm_import_memory]` attribute was also removed as LLD
has a native option for controlling this.
[gc]: https://reviews.llvm.org/D42511
This commit imports the `stdsimd` crate into the standard library,
creating an `arch` and `simd` module inside of both libcore and libstd.
Both of these modules are **unstable** and will continue to be so until
RFC 2335 is stabilized.
As a brief recap, the modules are organized as so:
* `arch` contains all current architectures with intrinsics, for example
`std::arch::x86`, `std::arch::x86_64`, `std::arch::arm`, etc. These
modules contain all of the intrinsics defined for the platform, like
`_mm_set1_epi8`.
* In the standard library, the `arch` module also exports a
`is_target_feature_detected` macro which performs runtime detection to
determine whether a target feature is available at runtime.
* The `simd` module contains experimental versions of strongly-typed
lane-aware SIMD primitives, to be fully fleshed out in a future RFC.
The main purpose of this commit is to start pulling in all these
intrinsics and such into the standard library on nightly and allow
testing and such. This'll help allow users to easily kick the tires and
see if intrinsics work as well as allow us to test out all the
infrastructure for moving the intrinsics into the standard library.
Is it really time? Have our months, no, *years* of suffering come to an end? Are we finally able to cast off the pall of Hoedown? The weight which has dragged us down for so long?
-----
So, timeline for those who need to catch up:
* Way back in December 2016, [we decided we wanted to switch out the markdown renderer](https://github.com/rust-lang/rust/issues/38400). However, this was put on hold because the build system at the time made it difficult to pull in dependencies from crates.io.
* A few months later, in March 2017, [the first PR was done, to switch out the renderers entirely](https://github.com/rust-lang/rust/pull/40338). The PR itself was fraught with CI and build system issues, but eventually landed.
* However, not all was well in the Rustdoc world. During the PR and shortly after, we noticed [some differences in the way the two parsers handled some things](https://github.com/rust-lang/rust/issues/40912), and some of these differences were major enough to break the docs for some crates.
* A couple weeks afterward, [Hoedown was put back in](https://github.com/rust-lang/rust/pull/41290), at this point just to catch tests that Pulldown was "spuriously" running. This would at least provide some warning about spurious tests, rather than just breaking spontaneously.
* However, the problems had created enough noise by this point that just a few days after that, [Hoedown was switched back to the default](https://github.com/rust-lang/rust/pull/41431) while we came up with a solution for properly warning about the differences.
* That solution came a few weeks later, [as a series of warnings when the HTML emitted by the two parsers was semantically different](https://github.com/rust-lang/rust/pull/41991). But that came at a cost, as now rustdoc needed proc-macro support (the new crate needed some custom derives farther down its dependency tree), and the build system was not equipped to handle it at the time. It was worked on for three months as the issue stumped more and more people.
* In that time, [bootstrap was completely reworked](https://github.com/rust-lang/rust/pull/43059) to change how it ordered compilation, and [the method by which it built rustdoc would change](https://github.com/rust-lang/rust/pull/43482), as well. This allowed it to only be built after stage1, when proc-macros would be available, allowing the "rendering differences" PR to finally land.
* The warnings were not perfect, and revealed a few [spurious](https://github.com/rust-lang/rust/pull/44368) [differences](https://github.com/rust-lang/rust/pull/45421) between how we handled the renderers.
* Once these were handled, [we flipped the switch to turn on the "rendering difference" warnings all the time](https://github.com/rust-lang/rust/pull/45324), in October 2017. This began the "warning cycle" for this change, and landed in stable in 1.23, on 2018-01-04.
* Once those warnings hit stable, and after a couple weeks of seeing whether we would get any more reports than what we got from sitting on nightly/beta, [we switched the renderers](https://github.com/rust-lang/rust/pull/47398), making Pulldown the default but still offering the option to use Hoedown.
And that brings us to the present. We haven't received more new issues from this in the meantime, and the "switch by default" is now on beta. Our reasoning is that, at this point, anyone who would have been affected by this has run into it already.
This commit introduces a separately compiled backend for Emscripten, avoiding
compiling the `JSBackend` target in the main LLVM codegen backend. This builds
on the foundation provided by #47671 to create a new codegen backend dedicated
solely to Emscripten, removing the `JSBackend` of the main codegen backend in
the process.
A new field was added to each target for this commit which specifies the backend
to use for translation, the default being `llvm` which is the main backend that
we use. The Emscripten targets specify an `emscripten` backend instead of the
main `llvm` one.
There's a whole bunch of consequences of this change, but I'll try to enumerate
them here:
* A *second* LLVM submodule was added in this commit. The main LLVM submodule
will soon start to drift from the Emscripten submodule, but currently they're
both at the same revision.
* Logic was added to rustbuild to *not* build the Emscripten backend by default.
This is gated behind a `--enable-emscripten` flag to the configure script. By
default users should neither check out the emscripten submodule nor compile
it.
* The `init_repo.sh` script was updated to fetch the Emscripten submodule from
GitHub the same way we do the main LLVM submodule (a tarball fetch).
* The Emscripten backend, turned off by default, is still turned on for a number
of targets on CI. We'll only be shipping an Emscripten backend with Tier 1
platforms, though. All cross-compiled platforms will not be receiving an
Emscripten backend yet.
This commit means that when you download the `rustc` package in Rustup for Tier
1 platforms you'll be receiving two trans backends, one for Emscripten and one
that's the general LLVM backend. If you never compile for Emscripten you'll
never use the Emscripten backend, so we may update this one day to only download
the Emscripten backend when you add the Emscripten target. For now though it's
just an extra 10MB gzip'd.
Closes#46819
This commit adds a new target to the compiler: wasm32-unknown-unknown. This
target is a reimagining of what it looks like to generate WebAssembly code from
Rust. Instead of using Emscripten which can bring with it a weighty runtime this
instead is a target which uses only the LLVM backend for WebAssembly and a
"custom linker" for now which will hopefully one day be direct calls to lld.
Notable features of this target include:
* There is zero runtime footprint. The target assumes nothing exists other than
the wasm32 instruction set.
* There is zero toolchain footprint beyond adding the target. No custom linker
is needed, rustc contains everything.
* Very small wasm modules can be generated directly from Rust code using this
target.
* Most of the standard library is stubbed out to return an error, but anything
related to allocation works (aka `HashMap`, `Vec`, etc).
* Naturally, any `#[no_std]` crate should be 100% compatible with this new
target.
This target is currently somewhat janky due to how linking works. The "linking"
is currently unconditional whole program LTO (aka LLVM is being used as a
linker). Naturally that means compiling programs is pretty slow! Eventually
though this target should have a linker.
This target is also intended to be quite experimental. I'm hoping that this can
act as a catalyst for further experimentation in Rust with WebAssembly. Breaking
changes are very likely to land to this target, so it's not recommended to rely
on it in any critical capacity yet. We'll let you know when it's "production
ready".
---
Currently testing-wise this target is looking pretty good but isn't complete.
I've got almost the entire `run-pass` test suite working with this target (lots
of tests ignored, but many passing as well). The `core` test suite is still
getting LLVM bugs fixed to get that working and will take some time. Relatively
simple programs all seem to work though!
---
It's worth nothing that you may not immediately see the "smallest possible wasm
module" for the input you feed to rustc. For various reasons it's very difficult
to get rid of the final "bloat" in vanilla rustc (again, a real linker should
fix all this). For now what you'll have to do is:
cargo install --git https://github.com/alexcrichton/wasm-gc
wasm-gc foo.wasm bar.wasm
And then `bar.wasm` should be the smallest we can get it!
---
In any case for now I'd love feedback on this, particularly on the various
integration points if you've got better ideas of how to approach them!
This commit migrates the in-tree `libcompiler_builtins` to the upstream version
at https://github.com/rust-lang-nursery/compiler-builtins. The upstream version
has a number of intrinsics written in Rust and serves as an in-progress rewrite
of compiler-rt into Rust. Additionally it also contains all the existing
intrinsics defined in `libcompiler_builtins` for 128-bit integers.
It's been the intention since the beginning to make this transition but
previously it just lacked the manpower to get done. As this PR likely shows it
wasn't a trivial integration! Some highlight changes are:
* The PR rust-lang-nursery/compiler-builtins#166 contains a number of fixes
across platforms and also some refactorings to make the intrinsics easier to
read. The additional testing added there also fixed a number of integration
issues when pulling the repository into this tree.
* LTO with the compiler-builtins crate was fixed to link in the entire crate
after the LTO process as these intrinsics are excluded from LTO.
* Treatment of hidden symbols was updated as previously the
`#![compiler_builtins]` crate would mark all symbol *imports* as hidden
whereas it was only intended to mark *exports* as hidden.
This avoids double compiled Cargo. Hopefully this would speed up (extended) compilation for ~10m.
Notes: when updating Cargo submodule, the replacement version may also need to be updated.
We've got a freshly minted beta compiler, let's update to use that on nightly!
This has a few other changes associated with it as well
* A bump to the rustc version number (to 1.19.0)
* Movement of the `cargo` and `rls` submodules to their "proper" location in
`src/tools/{cargo,rls}`. Now that Cargo workspaces support the `exclude`
option this can work.
* Updates of the `cargo` and `rls` submodules to their master branches.
* Tweak to the `src/stage0.txt` format to be more amenable for Cargo version
numbers. On the beta channel Cargo will bootstrap from a different version
than rustc (e.g. the version numbers are different), so we need different
configuration for this.
* Addition of `dev` as a readable key in the `src/stage0.txt` format. If present
then stage0 compilers are downloaded from `dev-static.rust-lang.org` instead
of `static.rust-lang.org`. This is added to accomodate our updated release
process with Travis and AppVeyor.
This causes problems when first cloning and bootstrapping the repository
unfortunately, so let's ensure that Cargo sticks around in its own workspace.
Because Cargo is a submodule it's not available by default on the inital clone
of the rust-lang/rust repository. Normally it's the responsibility of the
rustbuild to take care of this, but unfortunately to build rustbuild itself we
need to resolve the workspace conflicts.
To deal with this we'll just have to ensure that all submodules are in their own
workspace, which sort of makes sense anyway as updates to dependencies as
bugfixes to Cargo should go to rust-lang/cargo instead of rust-lang/rust. In any
case this commit removes Cargo from the global workspace which should resolve
the issues that we've been seeing.
To actually perform this the `cargo` submodule has been moved to the top
directory to ensure it's outside the scope of `src/Cargo.toml` as a workspace.
