Clang has done this by default since LLVM commit 1a963d3278c2 ("[Driver]
Make -moutline-atomics default for aarch64-fuchsia targets"), [1], so do
the same here.
[1]: 1a963d3278
Add default sanitizers to TargetOptions
Some sanitizers are part of a system's ABI, like the shadow call stack on Aarch64 and RISC-V Fuchsia. Typically ABI options have other spellings, but LLVM has, for historical reasons, marked this as a sanitizer instead of an alternate ABI option. As a result, Fuchsia targets may not be compiled against the correct ABI unless this option is set. This hasn't caused correctness problems, since the backend reserves the SCS register, and thus preserves its value. But this is an issue for unwinding, as the SCS will not be an array of PCs describing the call complete call chain, and will have gaps from callers that don't use the correct ABI.
In the long term, I'd like to see all the sanitizer configs that all frontends copy from clang moved into llvm's libFrontend, and exposed so that frontend consumers can use a small set of simple APIs to use sanitizers in a consistent way across the LLVM ecosystem, but that work is not yet ready today.
Some sanitizers are part of a system's ABI, like the shadow call stack
on Aarch64 and RISC-V Fuchsia. Typically ABI options have other
spellings, but LLVM has, for historical reasons, marked this as a
sanitizer instead of an alternate ABI option. As a result, Fuchsia
targets may not be compiled against the correct ABI unless this option
is set. This hasn't caused correctness problems, since the backend
reserves the SCS register, and thus preserves its value. But this is an
issue for unwinding, as the SCS will not be an array of PCs describing
the call complete call chain, and will have gaps from callers that don't
use the correct ABI.
In the long term, I'd like to see all the sanitizer configs that all
frontends copy from clang moved into llvm's libFrontend, and exposed so
that frontend consumers can use a small set of simple APIs to use
sanitizers in a consistent way across the LLVM ecosystem, but that work
is not yet ready today.
This updates the Fuchsia target spec with the [Clang Fuchsia driver],
which picks up a few changes:
* Adds `-z start-stop-visibility=hidden` and `-z rel` to the pre link
arguments.
* Adds `--execute-only` and `--fix-cortex-a53-843419` for
`aarch64-unknown-fuchsia`.
* Enables the cpu features equivalent to x86-64-v2 for
`x86_64-unknown-fuchsia`, which is our minimum supported x86_64.
platform according to [RFC-0073].
* Enables the cpu features `+crc,+aes,+sha2,+neon` on aarch64.
* Increases the max atomic width on 86_64 to 128.
* Enables stack probes and xray on aarch64 and riscv64.
[Clang Fuchsia driver]: 8374d42186/clang/lib/Driver/ToolChains/Fuchsia.cpp
[RFC-0073]: https://fuchsia.dev/fuchsia-src/contribute/governance/rfcs/0073_x86_64_platform_requirement
LLVM has added 3 new address spaces to support special Windows use
cases. These shouldn't trouble us for now, but LLVM requires matching
data layouts.
See llvm/llvm-project#111879 for details
LLVM has updated data layouts to specify `Fn32` on 64-bit ARM to avoid
C++ accidentally underaligning functions when trying to comply with
member function ABIs.
This should only affect Rust in cases where we had a similar bug (I
don't believe we have one), but our data layout must match to generate
code.
As a compatibility adaptatation, if LLVM is not version 19 yet, `Fn32`
gets voided from the data layout.
See llvm/llvm-project#90415
This adds four pieces of metadata to every target:
- description
- tier
- host tools
- std
This information is currently scattered across target docs and both
- not machine readable, making validation harder
- sometimes subtly encoding by the table it's in, causing mistakes and
making it harder to review changes to the properties
By putting it in the compiler, we improve this. Later, we will use this
canonical information to generate target documentation from it.
This is the short description (`64-bit MinGW (Windows 7+)`) including
the platform requirements.
The reason for doing it like this is that this PR will be quite prone to
conflicts whenever targets get added, so it should be as simple as
possible to get it merged. Future PRs which migrate targets are scoped
to groups of targets, so they will not conflict as they can just touch
these.
This moves some of the information from the rustc book into the
compiler.
It cannot be queried yet, that is future work. It is also future work to
fill out all the descriptions, which will coincide with the work of
moving over existing target docs to the new format.
