rust/compiler/rustc_session
bors 327c7ee436 Auto merge of #133099 - RalfJung:forbidden-hardfloat-features, r=workingjubilee
forbid toggling x87 and fpregs on hard-float targets

Part of https://github.com/rust-lang/rust/issues/116344, follow-up to https://github.com/rust-lang/rust/pull/129884:

The `x87`  target feature on x86 and the `fpregs` target feature on ARM must not be disabled on a hardfloat target, as that would change the float ABI. However, *enabling* `fpregs` on ARM is [explicitly requested](https://github.com/rust-lang/rust/issues/130988) as it seems to be useful. Therefore, we need to refine the distinction of "forbidden" target features and "allowed" target features: all (un)stable target features can determine on a per-target basis whether they should be allowed to be toggled or not. `fpregs` then checks whether the current target has the `soft-float` feature, and if yes, `fpregs` is permitted -- otherwise, it is not. (Same for `x87` on x86).

Also fixes https://github.com/rust-lang/rust/issues/132351. Since `fpregs` and `x87` can be enabled on some builds and disabled on others, it would make sense that one can query it via `cfg`. Therefore, I made them behave in `cfg` like any other unstable target feature.

The first commit prepares the infrastructure, but does not change behavior. The second commit then wires up `fpregs` and `x87` with that new infrastructure.

r? `@workingjubilee`
2024-12-13 19:43:00 +00:00
..
src Auto merge of #133099 - RalfJung:forbidden-hardfloat-features, r=workingjubilee 2024-12-13 19:43:00 +00:00
Cargo.toml compiler: Add rustc_abi dependence to the compiler 2024-10-27 21:10:58 -07:00
messages.ftl rust_for_linux: -Zreg-struct-return commandline flag for X86 (#116973) 2024-12-02 01:14:40 +07:00