Make wasm32 buildbot test LLVM backend
This adds the experimental targets option to configure so it can be used
by the builders and changes the wasm32 Dockerfile accordingly. Instead
of using LLVM from the emsdk, the builder's emscripten tools now uses
the Rust in-tree LLVM, since this is the one built with wasm support.
I think LLVM has had support for quite some time now for this, we just never got
around to testing it out and binding it. We've had some trouble landing this in
the past I believe, but it's time to try again!
This commit flags the `#[thread_local]` attribute as being available for Windows
targets and adds an implementation of `register_dtor` in the `thread::local`
module to ensure we can destroy these keys. The same functionality is
implemented in clang via a function called `__tlregdtor` (presumably provided in
some Windows runtime somewhere), but this function unfortunately does not take a
data pointer (just a thunk) which means we can't easily call it. For now
destructors are just run in the same way the Linux fallback is implemented,
which is just keeping track via a single OS-based TLS key.
This is used in wasm32-experimental-emscripten to ensure that emscripten
links against the libc bitcode files produced by the wasm LLVM backend,
instead of using fastcomp.
Enable wasm LLVM backend
Enables compilation to WebAssembly with the LLVM backend using the target triple "wasm32-unknown-unknown". This is the beginning of my work on #38804.
**edit:** The new new target is now wasm32-experimental-emscripten instead of wasm32-unknown-unknown.
The new target is wasm32-experimental-emscripten. Adds a new
configuration option to opt in to building experimental LLVM backends
such as the WebAssembly backend. The target name was chosen to be
similar to the existing wasm32-unknown-emscripten target so that the
build and tests would work with minimal other code changes. When/if the
new target replaces the old target, simply renaming it should just work.
Without that flag, LLVM generates unaligned memory access instructions, which are not allowed on ARMv5.
For example, the 'hello world' example from `cargo --new` failed with:
```
$ ./hello
Hello, world!
thread 'main' panicked at 'assertion failed: end <= len', src/libcollections/vec.rs:1113
note: Run with `RUST_BACKTRACE=1` for a backtrace.
```
I traced this error back to the following assembler code in `BufWriter::flush_buf`:
```
6f44: e28d0018 add r0, sp, #24
[...]
6f54: e280b005 add fp, r0, #5
[...]
7018: e5cd001c strb r0, [sp, #28]
701c: e1a0082a lsr r0, sl, #16
7020: 03a01001 moveq r1, #1
7024: e5cb0002 strb r0, [fp, #2]
7028: e1cba0b0 strh sl, [fp]
```
Note that `fp` points to `sp + 29`, so the three `str*`-instructions should fill up a 32bit - value at `sp + 28`, which is later used as the value `n` in `Ok(n) => written += n`. This doesn't work on ARMv5 as the `strh` can't write to the unaligned contents of `fp`, so the upper bits of `n` won't get cleared, leading to the assertion failure in Vec::drain.
With `+strict-align`, the code works as expected.
This support is needed for bindgen to work well on 32-bit Windows, and
also enables people to begin experimenting with C++ FFI support on that
platform.
Fixes#42044.
Add -march=armv7-a parameter to armv7 android linker
Without this option, the linker fails to link any library that uses `std::future`. The error points some undefined references, like `std::__future_base::_Result_base`.
For example, it fails to link rustc because llvm 4.0 uses `std::future`.
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64735
Looks like the LinkerFlavor change introduced in #40018 accidentally uses GCC for the WebAssembly target, causing Rust to never actually pass the post link args to emscripten. This then causes the code to be compiled as asm.js instead of WebAssembly, because the Binaryen tools never run due to the missing linker argument.
This patch adds a `-Z linker-flavor` flag to rustc which can be used to invoke
the linker using a different interface.
For example, by default rustc assumes that all the Linux targets will be linked
using GCC. This makes it impossible to use LLD as a linker using just `-C
linker=ld.lld` because that will invoke LLD with invalid command line
arguments. (e.g. rustc will pass -Wl,--gc-sections to LLD but LLD doesn't
understand that; --gc-sections would be the right argument)
With this patch one can pass `-Z linker-flavor=ld` to rustc to invoke the linker
using a LD-like interface. This way, `rustc -C linker=ld.lld -Z
linker-flavor=ld` will invoke LLD with the right arguments.
`-Z linker-flavor` accepts 4 different arguments: `em` (emcc), `ld`,
`gcc`, `msvc` (link.exe). `em`, `gnu` and `msvc` cover all the existing linker
interfaces. `ld` is a new flavor for interfacing GNU's ld and LLD.
This patch also changes target specifications. `linker-flavor` is now a
mandatory field that specifies the *default* linker flavor that the target will
use. This change also makes the linker interface *explicit*; before, it used to
be derived from other fields like linker-is-gnu, is-like-msvc,
is-like-emscripten, etc.
Another change to target specifications is that the fields `pre-link-args`,
`post-link-args` and `late-link-args` now expect a map from flavor to linker
arguments.
``` diff
- "pre-link-args": ["-Wl,--as-needed", "-Wl,-z,-noexecstack"],
+ "pre-link-args": {
+ "gcc": ["-Wl,--as-needed", "-Wl,-z,-noexecstack"],
+ "ld": ["--as-needed", "-z,-noexecstack"],
+ },
```
[breaking-change] for users of custom targets specifications
This commit deletes the internal liblog in favor of the implementation that
lives on crates.io. Similarly it's also setting a convention for adding crates
to the compiler. The main restriction right now is that we want compiler
implementation details to be unreachable from normal Rust code (e.g. requires a
feature), and by default everything in the sysroot is reachable via `extern
crate`.
The proposal here is to require that crates pulled in have these lines in their
`src/lib.rs`:
#![cfg_attr(rustbuild, feature(staged_api, rustc_private))]
#![cfg_attr(rustbuild, unstable(feature = "rustc_private", issue = "27812"))]
This'll mean that by default they're not using these attributes but when
compiled as part of the compiler they do a few things:
* Mark themselves as entirely unstable via the `staged_api` feature and the
`#![unstable]` attribute.
* Allow usage of other unstable crates via `feature(rustc_private)` which is
required if the crate relies on any other crates to compile (other than std).
* Update bootstrap to recognize the cputype 'sparcv9' (used on Solaris)
* Change to never use -fomit-frame-pointer on Solaris or for sparc
* Adds rust target sparcv9-sun-solaris
Fixes#39901
This might have performance implications. But do note that MSVC
disables FPO by default nowadays and it's use is limited in exception
heavy languages like C++.
Closes: #28218
Remove not(stage0) from deny(warnings)
Historically this was done to accommodate bugs in lints, but there hasn't been a
bug in a lint since this feature was added which the warnings affected. Let's
completely purge warnings from all our stages by denying warnings in all stages.
This will also assist in tracking down `stage0` code to be removed whenever
we're updating the bootstrap compiler.
Add socket timeout and ttl support in `sys::redox`
This adds support for `read_timeout`, `write_timeout`, and `ttl` on `TcpStream`, `TcpListener`, and `UdpSocket` in the `sys::redox` module.
The DNS lookup has been set to use a 5 second timeout by default.
Partial fix for #38489.
Fixes script name resolution for windows by invoking `emcc.bat` instead of `emcc`, etc.
Remaining issue:
```
Traceback (most recent call last):
File "C:\Program Files\Emscripten\emscripten\1.35.0\\emcc", line 1309, in <module>
final = shared.Building.llvm_opt(final, link_opts, DEFAULT_FINAL)
File "C:\Program Files\Emscripten\emscripten\1.35.0\tools\shared.py", line 1471, in llvm_opt
assert os.path.exists(target), 'Failed to run llvm optimizations: ' + output
AssertionError: Failed to run llvm optimizations:
```
Historically this was done to accommodate bugs in lints, but there hasn't been a
bug in a lint since this feature was added which the warnings affected. Let's
completely purge warnings from all our stages by denying warnings in all stages.
This will also assist in tracking down `stage0` code to be removed whenever
we're updating the bootstrap compiler.
Add a min_atomic_width target option, like max_atomic_width
Rationale: some ISAs, e.g. OR1K, do not have atomic instructions
for byte and halfword access, and at the same time do not have
a fixed endianness, which makes it unreasonable to implement these
through word-sized atomic accesses.
Rationale: some ISAs, e.g. OR1K, do not have atomic instructions
for byte and halfword access, and at the same time do not have
a fixed endianness, which makes it unreasonable to implement these
through word-sized atomic accesses.
Redox Cross Compilation
I will admit - there are things here that I wish I did not have to do. This completes the ability to create a cross compiler from the rust repository for `x86_64-unknown-redox`. I will document this PR with inline comments explaining some things.
[View this gist to see how a cross compiler is built](https://gist.github.com/jackpot51/6680ad973986e84d69c79854249f2b7e)
Prior discussion of a smaller change is here: https://github.com/rust-lang/rust/pull/38366
