[beetrees]

On RISC-V, callee-saved floating point registers are only callee-saved up to ABI_FLEN bits; the rest of the register is considered temporary. For clobber_abi("C"), as LLVM doesn't support partial register clobbers, this requires the callee-saved floating point registers to be clobbered.

These issues are noticeable in beta but not stable due to the recent stabilisation of the f and d target features (tracking issue: #150257) so this probably needs a beta backport unless the stabilisation is reverted.

[rustbot]

r? @petrochenkov

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[rust-log-analyzer]

The job test-aarch64-gnu-llvm-22-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[RUSTC-TIMING] rustc_expand_queries test:false 0.430
   Compiling rustc_public_bridge v0.0.0 (/checkout/compiler/rustc_public_bridge)
[RUSTC-TIMING] rustc_resolve test:false 29.568

##[error]The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.
Session terminated, killing shell...::group::Clock drift check
  local time: Mon Oct  5 20:17:11 UTC 2026
  network time: Mon, 05 Oct 2026 20:17:11 GMT
##[endgroup]
 ...killed.
##[error]The operation was canceled.

[tgross35]

Relevant stabilization PR: #161385

[petrochenkov]

r? @Amanieu