add target feature ABI checks for SPARC by RalfJung · Pull Request #160562 · rust-lang/rust

RalfJung · 2026-08-05T12:38:54Z

Fixes #157083
MCP: rust-lang/compiler-team#1028

Cc @psumbera @kulikjak @workingjubilee @taiki-e @jonathanpallant I hope this makes sense :)

rustbot · 2026-08-05T12:38:57Z

These commits modify compiler targets.
(See the Target Tier Policy.)

rustbot · 2026-08-05T12:39:00Z

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RalfJung · 2026-08-05T13:19:07Z

Ah, the sparc-unknown-linux-gnu target enables v8plus... that's a bit surprising given that I was told that the ABI isn't actually implemented in LLVM yet?
This is also a tier 3 target without a listed target maintainer, so I feel inclined to just remove the target feature from the target spec.

RalfJung · 2026-08-05T13:50:14Z

        VecDefault = "vec-default",
        VecExtAbi = "vec-extabi",
        X32 = "x32",
+        V8Plus = "v8plus",


Do we need any kind of process for a new cfg value here?

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I filed an MCP: rust-lang/compiler-team#1028

fee1-dead · 2026-08-09T18:51:19Z

@rustbot reroll

chenyukang · 2026-08-10T01:25:06Z

@rustbot reroll

hanna-kruppe · 2026-08-11T17:08:07Z

I don't really know anything about SPARC nor have I touched the compiler machinery for these checks yet. Maybe one of the people pinged earlier wants to take this? If not, I guess that's my chance to learn some more funny cursed trivia, but it'll take a while.

rustbot · 2026-08-17T09:30:36Z

These commits modify compiler targets.
(See the Target Tier Policy.)

rustbot · 2026-08-17T09:30:38Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

RalfJung · 2026-08-26T20:17:31Z

@hanna-kruppe MCP finished, now only the review is left.

Or maybe one of the folks reading along could do that (@workingjubilee @tgross35 ?)

One point that was not fully resolved in the MCP is "v8plus" vs "v8+" for the cfg(target_abi) value. I don't really care either way, it seems hardly anyone else cares either. The only person that expressed a preference was @tgross35 who preferred "v8+". Do the target maintainers have an opinion?

jonathanpallant · 2026-08-27T09:38:26Z

AFAIK this only applies to sparc-unknown-linux-gnu right? There is no target maintainer, nor platform docs page. So I think you can do whatever you like.

RalfJung · 2026-08-27T09:45:31Z

Oh, right.

RalfJung · 2026-08-27T19:30:04Z

We're going with "v8plus": #t-compiler/major changes > Expose `target_abi = "v8plus"` on sparc-… compiler-team#1028 @ 💬.

This PR is ready then :)

RalfJung · 2026-08-27T19:30:22Z

r? @tgross35

rustbot · 2026-08-27T19:30:28Z

tgross35 is currently at their maximum review capacity.
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tgross35 · 2026-08-27T19:38:11Z

+                match self.rustc_abi {
+                    None => FeatureConstraints {
+                        required: &[],
+                        incompatible: &["soft-float", "v8plus"],
+                    },
+                    Some(RustcAbi::SparcV8Plus) => {
+                        FeatureConstraints { required: &["v8plus"], incompatible: &["soft-float"] }
+                    }
+                    _ => unreachable!(),
+                }
+            }
+            Arch::Sparc64 => {
+                // We currently don't have a soft-float target for SPARC64.
+                // v8plus is for 32bit SPARC only.
+                FeatureConstraints { required: &[], incompatible: &["soft-float", "v8plus"] }


Does the incompatible list make these target modifiers and prevent linking? I'm not sure whether that is something we should be testing.

View changes since the review

This system predates target modifiers so it is currently unrelated (though I am trying to marry them in #160593).

What this does is emit a warning whenever these target features are enabled via -Ctarget-feature or even implicitly via -Ctarget-cpu (with a note that this warning will become a hard error eventually). It also causes a hard error when they are enabled via #[target_feature].

tgross35

In that case, LGTM!

@bors r+

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rust-bors · 2026-08-27T21:12:32Z

📌 Commit e7cadc3 has been approved by tgross35

It is now in the queue for this repository.

@psumbera

add target feature ABI checks for SPARC Fixes rust-lang#157083 MCP: rust-lang/compiler-team#1028 Cc @psumbera @kulikjak @workingjubilee @taiki-e @jonathanpallant I hope this makes sense :)

@psumbera

add target feature ABI checks for SPARC Fixes rust-lang#157083 MCP: rust-lang/compiler-team#1028 Cc @psumbera @kulikjak @workingjubilee @taiki-e @jonathanpallant I hope this makes sense :)

…uwer Rollup of 21 pull requests Successful merges: - #158609 (Update sccache to 0.16.0) - #150075 (Implement clamp_to) - #159103 (fix(reborrow): recursive implementation) - #160562 (add target feature ABI checks for SPARC) - #160848 (std: avoid aliasing violations when wrapping opaque C types) - #161421 (Include startup crt objects on WASI for more outputs) - #161805 (Prefer ambiguous candidates when deduplicating traits in scope, so `ambiguous_glob_imported_traits` doesn't depend on import order) - #161862 (Put data segment in specified section with link_section on wasm) - #161866 (delegation: add tests fixating behavior of delegating to default trait implementations) - #161456 (reduce perf impact of scalar size checks) - #161528 (Add regression test to ensure optimal compilation) - #161666 (Print vendor instructions in `x vendor`) - #161730 (Improve type mismatch annotation for lets with block-wrapped initializers) - #161828 (Never type after-stabilization cleanup) - #161859 (Do not optimize MIR for comptime ConstFns) - #161860 (atomicptr.rs test: remove unused import) - #161870 (bind to [::1] instead of 127.0.0.1 in documentation examples for v6 UDP methods) - #161876 (rustdoc: Correctly handle when a macro generates multiple items in `--generate-macro-expansion`) - #161889 (Add link to ownership section in ptr::read docs) - #161890 (rustdoc: some clarifying comments) - #161891 (Mark `extern_item_impls` feature as incomplete) Failed merges: - #161702 (Use `drop_guard` in some places in {core,alloc,std})

@psumbera

add target feature ABI checks for SPARC Fixes rust-lang#157083 MCP: rust-lang/compiler-team#1028 Cc @psumbera @kulikjak @workingjubilee @taiki-e @jonathanpallant I hope this makes sense :)

…uwer Rollup of 21 pull requests Successful merges: - #150075 (Implement clamp_to) - #159103 (fix(reborrow): recursive implementation) - #160562 (add target feature ABI checks for SPARC) - #160848 (std: avoid aliasing violations when wrapping opaque C types) - #161421 (Include startup crt objects on WASI for more outputs) - #161805 (Prefer ambiguous candidates when deduplicating traits in scope, so `ambiguous_glob_imported_traits` doesn't depend on import order) - #161862 (Put data segment in specified section with link_section on wasm) - #161866 (delegation: add tests fixating behavior of delegating to default trait implementations) - #157218 (Track items behind `cfg_select` in the same way we do for `cfg`) - #161456 (reduce perf impact of scalar size checks) - #161528 (Add regression test to ensure optimal compilation) - #161666 (Print vendor instructions in `x vendor`) - #161730 (Improve type mismatch annotation for lets with block-wrapped initializers) - #161828 (Never type after-stabilization cleanup) - #161859 (Do not optimize MIR for comptime ConstFns) - #161860 (atomicptr.rs test: remove unused import) - #161870 (bind to [::1] instead of 127.0.0.1 in documentation examples for v6 UDP methods) - #161876 (rustdoc: Correctly handle when a macro generates multiple items in `--generate-macro-expansion`) - #161889 (Add link to ownership section in ptr::read docs) - #161890 (rustdoc: some clarifying comments) - #161891 (Mark `extern_item_impls` feature as incomplete) Failed merges: - #161702 (Use `drop_guard` in some places in {core,alloc,std})

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Aug 5, 2026

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RalfJung force-pushed the sparc branch from c454884 to 5ee14f5 Compare August 5, 2026 13:48

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sparc: make ABI consistent with clang #160401

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RalfJung force-pushed the sparc branch from 5ee14f5 to e301f22 Compare August 5, 2026 15:06

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turn ABI-controlling target features into a target modifier #160593

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RalfJung mentioned this pull request Aug 7, 2026

Expose target_abi = "v8plus" on sparc-unknown-linux-gnu rust-lang/compiler-team#1028

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add target feature ABI checks for SPARC

e7cadc3

RalfJung force-pushed the sparc branch from e301f22 to e7cadc3 Compare August 17, 2026 09:30

This was referenced Aug 17, 2026

Introduce aarch64-unknown-linux-pauthtest target #155722

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Tracking Issue for sparc_target_feature #132783

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Add floating point inline ASM support for SPARC #160949

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RalfJung mentioned this pull request Aug 26, 2026

Tracking issue for MCP 1028: Expose target_abi = "v8plus" on sparc-unknown-linux-gnu #161835

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RalfJung removed the S-waiting-on-MCP Status: PR has a compiler MCP and is waiting for the compiler MCP to complete. label Aug 26, 2026

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rust-bors Bot 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 27, 2026

JonathanBrouwer mentioned this pull request Aug 28, 2026

Rollup of 18 pull requests #161901

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Rollup of 21 pull requests #161905

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JonathanBrouwer mentioned this pull request Aug 28, 2026

Rollup of 21 pull requests #161906

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