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@tgross35 tgross35 commented Aug 5, 2025

Subtree update of compiler-builtins to rust-lang/compiler-builtins@87a66ec.

Created using https://github.com/rust-lang/josh-sync.

r? @ghost

tgross35 and others added 24 commits July 21, 2025 12:18
We are getting warnings in CI about unsupported features. There isn't
any reason to use stable rustfmt so switch the channel here.
We now have access to native runners, so make use of them for these
architectures. The existing ppc64le Docker job is kept for now.
This includes a qemu update from 8.2.2 to 9.2.1 which should hopefully
fix some bugs we have encountered.

PowerPC64LE is skipped for now because the new version seems to cause a
number of new SIGILLs.
Wasm support has since been released, so we no longer need to depend on
a git version of `object`.
We pretty often get at least one job failed because of failure to pull
the musl git repo. Switch this to the unofficial mirror [1] which should
be more reliable.

Link: https://github.com/kraj/musl [1]
Update the last remaining image.

For this to work, the `QEMU_CPU=POWER8` configuration needed to be
dropped to avoid a new SIGILL. Doing some debugging locally, the crash
comes from an `extswsli` (per `powerpc:common64` in gdb-multiarch) in
the `ld64.so` available with PowerPC, which qemu rejects when set to
power8. Testing a build with `+crt-static` hits the same issue at a
`maddld` in `__libc_start_main_impl`.

Rust isn't needed to reproduce this:

    $ cat a.c
    #include <stdio.h>

    int main() {
            printf("Hello, world!\n");
    }
    $ powerpc64le-linux-gnu-gcc a.c
    $ QEMU_CPU=power8 QEMU_LD_PREFIX=/usr/powerpc64le-linux-gnu/ ./a.out
    qemu: uncaught target signal 4 (Illegal instruction) - core dumped
    Illegal instruction

So the cross toolchain provided by Debian must have a power9 baseline
rather than rustc's power8. Alternatively, qemu may be incorrectly
rejecting these instructions (I can't find a source on whether or not
they should be available for power8). Testing instead with the `-musl`
toolchain and ppc linker from musl.cc works correctly.

In any case, things work with the default qemu config so it seems fine
to drop. The env was originally added in 5d164a4edafb ("fix the
powerpc64le target") but whatever the problem was there appears to no
longer be relevant.
Most of these were skipped because of a bug with the platform
implementation, or some kind of crash unwinding. Since the upgrade to
Ubuntu 25.04, these all seem to be resolved with the exception of a bug
in the host `__floatundisf` [1].

[1] rust-lang/compiler-builtins#384 (comment)
The LLVM issue was resolved a while ago, these should no longer be a
problem.
The fix has since made it to nightly, so the skips here can be removed.
Emit `x86_no_sse` in the compiler-builtins (and builtins-test) build
script, and use it to simplify `all(target_arch = "x86",
not(target_fefature = "sse))` configuration.
Silence the approximate constant lint because it is noisy and not always
correct. `single_component_path_imports` is also not accurate when built
as part of `compiler-builtins`, so that needs to be `allow`ed as well.
Possible workaround for
rust-lang/compiler-builtins#976 (comment)

Inline assembly in the body of a function currently causes the compiler
to consider that function possibly unwinding, even if said asm
originated from inlining an `extern "C"` function. This patch wraps the
problematic callsite with `#[inline(never)]`.
Assembly-related configuration was added in 1621c6dbf9eb ("Use
`specialized-div-rem` 1.0.0 for division algorithms") to account for
Cranelift not yet supporting assembly. This hasn't been relevant for a
while, so we no longer need to gate `asm!` behind this configuration.
Thus, remove `cfg(not(feature = "no-asm"))` in places where there is no
generic fallback.

There are other cases, however, where setting the `no-asm` configuration
enables testing of generic version of builtins when there are platform-
specific implementations available; these cases are left unchanged. This
could be improved in the future by exposing both versions for testing
rather than using a configuration and running the entire testsuite
twice.

This is the compiler-builtins portion of
rust-lang#144471.
So there will no longer be the need to close and reopen sync PRs in
order for CI to run.
Rather than setting an environment variable in the workflow job based on
whether or not the environment is non-MinGW Windows, we can just check
this in the ci script.

This was originally added in b0f19660f0 ("Add tests for UNC paths on
windows builds") and its followup commits.
Replace the current system with something that is more structured and
will also catch unknown directives.
Use `tee` rather than printing to both stdout and stderr.
Introduce a new directive `ci: test-libm` to ensure tests run.
Currently, a failure in `ci-util.py` does not cause the job to fail
because the pipe eats the failure status . Set pipefail to fix this.

Fixes: ff2cc0e38e3e ("ci: Don't print output twice in `ci-util`")
Currently, attributes for `no-panic` are gated behind both the `test`
config and `assert_no_panic`, because `no-panic` is a dev dependency (so
only available with test configuration). However, we only emit
`assert_no_panic` when the test config is also set anyway, so there
isn't any need to gate on both.

Replace gates on `all(test, assert_no_panic)` with only
`assert_no_panic`. This is simpler, and also has the benefit that
attempting to check for panics without `--test` errors.
Currently we run the `rustc` from the `RUSTC` environment variable to
figure out whether or not to enable `f16` and `f128`, based on the
`target_has_reliable_{f16,f128}` config. However, this does not know
about the codegen backend used, and the backend isn't trivial to check
in a build script (usually it gets set via `RUSTFLAGS`).

It turns out we don't actually need to run `rustc` here: Cargo
unconditionally emits all config from the relevant compiler as
`CARGO_CFG_*` variables, regardless of whether or not they are known
options. Switch to checking these for setting config rather than
invoking `rustc`.

As an added advantage, this will work with target.json files without any
special handling.

Fixes: ed17b95715dd ("Use the compiler to determine whether or not to enable `f16` and `f128`")
@rustbot rustbot added A-compiler-builtins Area: compiler-builtins (https://github.com/rust-lang/compiler-builtins) S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Aug 5, 2025
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rustbot commented Aug 5, 2025

⚠️ Warning ⚠️

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tgross35 commented Aug 5, 2025

@bors r+

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bors commented Aug 5, 2025

📌 Commit fbc700f has been approved by tgross35

It is now in the queue for this repository.

@bors bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Aug 5, 2025
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6 participants