rust/compiler/rustc_target
Michael Goulet 7b40a9b7c6
Rollup merge of #133102 - RalfJung:aarch64-softfloat, r=davidtwco,wesleywiser
aarch64 softfloat target: always pass floats in int registers

This is a part of https://github.com/rust-lang/rust/issues/131058: on softfloat aarch64 targets, the float registers may be unavailable. And yet, LLVM will happily use them to pass float types if the corresponding target features are enabled. That's a problem as it means enabling/disabling `neon` instructions can change the ABI.

Other targets have a `soft-float` target feature that forces the use of the soft-float ABI no matter whether float registers are enabled or not; aarch64 has nothing like that.

So we follow the aarch64 [softfloat ABI](https://github.com/rust-lang/rust/issues/131058#issuecomment-2385027423) and treat floats like integers for `extern "C"` functions. For the "Rust" ABI, we do the same for scalars, and then just do something reasonable for ScalarPair that avoids the pointer indirection.

Cc ```@workingjubilee```
2024-11-22 21:07:39 -05:00
..
src Rollup merge of #133102 - RalfJung:aarch64-softfloat, r=davidtwco,wesleywiser 2024-11-22 21:07:39 -05:00
Cargo.toml Remove unused intercrate dependencies 2024-11-07 14:17:16 +00:00
README.md Fix outdated crate names in compiler docs 2021-04-08 11:12:14 -05:00

rustc_target contains some very low-level details that are specific to different compilation targets and so forth.

For more information about how rustc works, see the rustc dev guide.