rust/compiler/rustc_codegen_llvm
bors e8c698bb3b Auto merge of #129884 - RalfJung:forbidden-target-features, r=workingjubilee
mark some target features as 'forbidden' so they cannot be (un)set with -Ctarget-feature

The context for this is https://github.com/rust-lang/rust/issues/116344: some target features change the way floats are passed between functions. Changing those target features is unsound as code compiled for the same target may now use different ABIs.

So this introduces a new concept of "forbidden" target features (on top of the existing "stable " and "unstable" categories), and makes it a hard error to (un)set such a target feature. For now, the x86 and ARM feature `soft-float` is on that list. We'll have to make some effort to collect more relevant features, and similar features from other targets, but that can happen after the basic infrastructure for this landed. (These features are being collected in https://github.com/rust-lang/rust/issues/131799.)

I've made this a warning for now to give people some time to speak up if this would break something.

MCP: https://github.com/rust-lang/compiler-team/issues/780
2024-11-05 16:25:45 +00:00
..
src Auto merge of #129884 - RalfJung:forbidden-target-features, r=workingjubilee 2024-11-05 16:25:45 +00:00
Cargo.toml compiler: Factor rustc_target::abi out of cg_llvm 2024-10-08 18:24:56 -07:00
messages.ftl mark some target features as 'forbidden' so they cannot be (un)set 2024-11-04 22:56:47 +01:00
README.md

The codegen crate contains the code to convert from MIR into LLVM IR, and then from LLVM IR into machine code. In general it contains code that runs towards the end of the compilation process.

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