compiler-builtins subtree update #144974

tgross35 · 2025-08-05T22:08:50Z

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

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

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)]`.

Fixes: rust-lang/compiler-builtins#837 The assembly is based on - https://github.com/NetBSD/src/blob/20433927938987dd64c8f6aa46904b7aca3fa39e/lib/libm/arch/i387/s_floor.S - https://github.com/NetBSD/src/blob/20433927938987dd64c8f6aa46904b7aca3fa39e/lib/libm/arch/i387/s_ceil.S Which both state /* * Written by J.T. Conklin <[email protected]>. * Public domain. */ Which I believe means we're good in terms of licensing.

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 · 2025-08-05T22:08:55Z

⚠️ Warning ⚠️

This PR is based on an upstream commit that is 18 days old.

It's recommended to update your branch according to the rustc-dev-guide.

tgross35 · 2025-08-05T23:19:48Z

@bors r+

bors · 2025-08-05T23:19:51Z

📌 Commit fbc700f has been approved by tgross35

It is now in the queue for this repository.

compiler-builtins subtree update Subtree update of `compiler-builtins` to rust-lang/compiler-builtins@87a66ec. Created using https://github.com/rust-lang/josh-sync. r? ``@ghost``

Rollup of 20 pull requests Successful merges: - #137831 (Tweak auto trait errors) - #143028 (emit `StorageLive` and schedule `StorageDead` for `let`-`else`'s bindings after matching) - #143764 (lower pattern bindings in the order they're written and base drop order on primary bindings' order) - #143808 (Port `#[should_panic]` to the new attribute parsing infrastructure ) - #143906 (Miri: non-deterministic floating point operations in `foreign_items`) - #143929 (Mark all deprecation lints in name resolution as deny-by-default and report-in-deps) - #144133 (Stabilize const TypeId::of) - #144439 (Introduce ModernIdent type to unify macro 2.0 hygiene handling) - #144473 (Address libunwind.a inconsistency issues in the bootstrap program) - #144659 (bootstrap: refactor mingw dist and fix gnullvm) - #144705 (compiler-builtins: plumb LSE support for aarch64 on linux/gnu when optimized-compiler-builtins not enabled) - #144807 (Streamline config in bootstrap) - #144900 (Stabilize `unsigned_signed_diff` feature) - #144903 (Rename `begin_panic_handler` to `panic_handler`) - #144931 ([win][arm64ec] Fix msvc-wholearchive for Arm64EC) - #144974 (compiler-builtins subtree update) - #144997 (bump bootstrap compiler to 1.90 beta) - #145004 (Couple of minor cleanups) - #145009 (A couple small changes for rust-analyzer next-solver work) - #145014 (Revert "Preserve the .debug_gdb_scripts section") r? `@ghost` `@rustbot` modify labels: rollup

compiler-builtins subtree update Subtree update of `compiler-builtins` to rust-lang/compiler-builtins@87a66ec. Created using https://github.com/rust-lang/josh-sync. r? ```@ghost```

Rollup of 8 pull requests Successful merges: - #144705 (compiler-builtins: plumb LSE support for aarch64 on linux/gnu when optimized-compiler-builtins not enabled) - #144857 (Port `#[allow_internal_unsafe]` to the new attribute system) - #144900 (Stabilize `unsigned_signed_diff` feature) - #144903 (Rename `begin_panic_handler` to `panic_handler`) - #144974 (compiler-builtins subtree update) - #145004 (Couple of minor cleanups) - #145007 (Fix build/doc/test of error index generator) - #145018 (Derive `Hash` for rustc_public types) r? `@ghost` `@rustbot` modify labels: rollup

tgross35 · 2025-08-07T23:29:11Z

#145063 (comment)
@bors r-
@bors2 try jobs=x86_64-apple-2

rust-bors · 2025-08-07T23:29:15Z

⌛ Trying commit fbc700f with merge 097896e…

To cancel the try build, run the command @bors try cancel.

compiler-builtins subtree update try-job: x86_64-apple-2

rust-bors · 2025-08-08T00:27:48Z

☀️ Try build successful (CI)
Build commit: 097896e (097896e3d472473f664a7fada4aa0947c74b9efa, parent: 2fd855fbfc8239285aa2d596f76a8cc75e17ce02)

tgross35 · 2025-08-08T00:30:04Z

@bors r+

bors · 2025-08-08T00:30:06Z

📌 Commit fbc700f has been approved by tgross35

It is now in the queue for this repository.

compiler-builtins subtree update Subtree update of `compiler-builtins` to rust-lang/compiler-builtins@87a66ec. Created using https://github.com/rust-lang/josh-sync. r? `@ghost`

Rollup of 9 pull requests Successful merges: - #144705 (compiler-builtins: plumb LSE support for aarch64 on linux/gnu when optimized-compiler-builtins not enabled) - #144857 (Port `#[allow_internal_unsafe]` to the new attribute system) - #144900 (Stabilize `unsigned_signed_diff` feature) - #144903 (Rename `begin_panic_handler` to `panic_handler`) - #144974 (compiler-builtins subtree update) - #145007 (Fix build/doc/test of error index generator) - #145018 (Derive `Hash` for rustc_public types) - #145045 (doc(library): Fix Markdown in `Iterator::by_ref`) - #145046 (Fix doc comment of File::try_lock and File::try_lock_shared) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #144974 - tgross35:update-builtins, r=tgross35 compiler-builtins subtree update Subtree update of `compiler-builtins` to rust-lang/compiler-builtins@87a66ec. Created using https://github.com/rust-lang/josh-sync. r? ``@ghost``

Kobzol · 2025-08-08T08:16:31Z

@rust-timer build c2b481d

Testing for regression in #145074.

tgross35 · 2025-08-08T08:25:20Z

I don't think this is likely to be the cause - it's mostly CI and test changes plus a i586-specific speedup for floor and ceil. But it doesn't hurt to check :)

rust-timer · 2025-08-08T10:38:10Z

Finished benchmarking commit (c2b481d): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results (secondary -2.9%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.9%	[-2.9%, -2.9%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary 0.8%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.5%	[2.4%, 2.7%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.6%	[-2.6%, -2.6%]	1
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 465.2s -> 464.707s (-0.11%)
Artifact size: 377.41 MiB -> 377.37 MiB (-0.01%)

Rollup of 9 pull requests Successful merges: - rust-lang/rust#144705 (compiler-builtins: plumb LSE support for aarch64 on linux/gnu when optimized-compiler-builtins not enabled) - rust-lang/rust#144857 (Port `#[allow_internal_unsafe]` to the new attribute system) - rust-lang/rust#144900 (Stabilize `unsigned_signed_diff` feature) - rust-lang/rust#144903 (Rename `begin_panic_handler` to `panic_handler`) - rust-lang/rust#144974 (compiler-builtins subtree update) - rust-lang/rust#145007 (Fix build/doc/test of error index generator) - rust-lang/rust#145018 (Derive `Hash` for rustc_public types) - rust-lang/rust#145045 (doc(library): Fix Markdown in `Iterator::by_ref`) - rust-lang/rust#145046 (Fix doc comment of File::try_lock and File::try_lock_shared) r? `@ghost` `@rustbot` modify labels: rollup

tgross35 and others added 24 commits July 21, 2025 12:18

ci: Switch to nightly rustfmt

ed50029

We are getting warnings in CI about unsupported features. There isn't any reason to use stable rustfmt so switch the channel here.

ci: Add native PowerPC64LE and s390x jobs

08bca4d

We now have access to native runners, so make use of them for these architectures. The existing ppc64le Docker job is kept for now.

ci: Update to the latest ubuntu:25.04 Docker images

fcc7824

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.

symcheck: Switch the object dependency from git to crates.io

95c4263

Wasm support has since been released, so we no longer need to depend on a git version of `object`.

ci: Use a mirror for musl

83aea65

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]

Enable tests that were skipped on aarch64

b168793

The LLVM issue was resolved a while ago, these should no longer be a problem.

Enable skipped f32 and f64 multiplication tests

0b6c1d3

The fix has since made it to nightly, so the skips here can be removed.

Use x86_no_sse configuration in more places

9dad77f

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.

libm: Update for new warn-by-default clippy lints

4743158

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.

Switch to using a GH app for authenticating sync PRs

54f6ab7

So there will no longer be the need to close and reopen sync PRs in order for CI to run.

cleanup: Trim trailing whitespace

54a4f86

ci: Switch to strongly typed directives

ab8a2e1

Replace the current system with something that is more structured and will also catch unknown directives.

ci: Don't print output twice in ci-util

eafafc4

Use `tee` rather than printing to both stdout and stderr.

ci: Commonize the way PrInfo is loaded from env

c045c9b

ci: Add a way to run libm tests that would otherwise be skipped

4ebfdf7

Introduce a new directive `ci: test-libm` to ensure tests run.

ci: Set pipefail before running ci-util

3cbd088

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`")

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

Zalathar mentioned this pull request Aug 7, 2025

Rollup of 21 pull requests #145034

Closed

Zalathar mentioned this pull request Aug 7, 2025

Rollup of 20 pull requests #145039

Closed

tgross35 mentioned this pull request Aug 7, 2025

Rollup of 8 pull requests #145063

Closed

bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Aug 7, 2025

rust-bors bot added a commit that referenced this pull request Aug 7, 2025

Auto merge of #144974 - tgross35:update-builtins, r=<try>

097896e

compiler-builtins subtree update try-job: x86_64-apple-2

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Aug 8, 2025

tgross35 mentioned this pull request Aug 8, 2025

Rollup of 9 pull requests #145074

Merged

bors merged commit 0a1e0c6 into rust-lang:master Aug 8, 2025
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rustbot added this to the 1.91.0 milestone Aug 8, 2025

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Overall result: no relevant changes - no action needed

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