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Jonathan Brouwer
ca1b24406d
prefer actual ABI-controling fields over target.abi when making ABI decisions We don't actually check that `abi` is consistent with the fields that control the ABI, e.g. one could set `llvm_abiname` to "ilp32e" on a riscv target without setting a matching `abi`. So, if we need to make actual decisions, better to use the source of truth we forward to LLVM than the informational string we forward to the user. This is a breaking change for aarch64 JSON target specs: setting `abi` to "softfloat" is no longer enough; one has to also set `rustc_abi` to "softfloat". That is consistent with riscv and arm32, but it's still surprising. Cc @Darksonn in case this affects the Linux kernel. Also see https://github.com/rust-lang/rust/pull/153035 which does something similar for PowerPC, and [Zulip](https://rust-lang.zulipchat.com/#narrow/channel/131828-t-compiler/topic/De-spaghettifying.20ABI.20controls/with/575095372). Happy to delay this PR if someone has a better idea. Cc @folkertdev @workingjubilee
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.