⚠️ #[rustc_intrinsic_const_stable_indirect] controls whether intrinsics can be exposed to stable const
code; adding it needs t-lang approval.

cc @rust-lang/wg-const-eval

Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter
gets adapted for the changes, if necessary.

cc @rust-lang/miri, @RalfJung, @oli-obk, @lcnr

Some changes occurred to the platform-builtins intrinsics. Make sure the
LLVM backend as well as portable-simd gets adapted for the changes.

cc @antoyo, @GuillaumeGomez, @bjorn3, @calebzulawski, @programmerjake

r? @joboet

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So you plan to soon const-stabilize functions using these intrinsics?

I won't say soon (it would require t-libs-api approval), but yes the plan is eventually to stabilize them

Usually we do the t-lang FCP for const intrinsics as part of that stabilization, not preemptively.

r? @RalfJung
I'm really not sure who normally handles these PRs, feel free to reassign as necessary.

@rustbot author
based on the comments above

I would propose to remove all controversial cases, then we can proceed to FCP.

Reminder, once the PR becomes ready for a review, use @rustbot ready.

Apologize for the delay. @RalfJung do the above-mentioned caveats also apply to simd_fmax and simd_fmin?

Yeah, they do.

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.

@rustbot ready

I have removed the attributes from simd_reduce_{min,max}, simd_f{max,min} and simd_relaxed_fma.

I have nominated this for t-lang discussion. It'd be good to update the PR description to give the required context to team members visiting this during triage: which new capabilities are exposed to const code here, and what does the test coverage look like?