Rollup merge of #125154 - FractalFir:fnabi_doc, r=compiler-errors

Small improvements to the documentaion of FnAbi

I have updated the documentation of  `FnAbi`.

The `arg` and `ret` fields are no longer LLVM types, but Rust types(`ArgAbi` contains a `TyAndLayout` and a `PassMode`), so I changed the documentation to reflect that.

Besides that, I also added documentation to other fields, and added a clarification about the differences between `FnAbi` and `FnSig`, since this is not something that is immediately obvious.
This commit is contained in:
León Orell Valerian Liehr 2024-05-15 22:01:20 +02:00 committed by GitHub
commit 601e5d199f
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@ -779,16 +779,21 @@ pub fn as_str(&self) -> &'static str {
/// Metadata describing how the arguments to a native function
/// should be passed in order to respect the native ABI.
///
/// The signature represented by this type may not match the MIR function signature.
/// Certain attributes, like `#[track_caller]` can introduce additional arguments, which are present in [`FnAbi`], but not in `FnSig`.
/// While this difference is rarely relevant, it should still be kept in mind.
///
/// I will do my best to describe this structure, but these
/// comments are reverse-engineered and may be inaccurate. -NDM
#[derive(Clone, PartialEq, Eq, Hash, HashStable_Generic)]
pub struct FnAbi<'a, Ty> {
/// The LLVM types of each argument.
/// The type, layout, and information about how each argument is passed.
pub args: Box<[ArgAbi<'a, Ty>]>,
/// LLVM return type.
/// The layout, type, and the way a value is returned from this function.
pub ret: ArgAbi<'a, Ty>,
/// Marks this function as variadic (accepting a variable number of arguments).
pub c_variadic: bool,
/// The count of non-variadic arguments.
@ -796,9 +801,9 @@ pub struct FnAbi<'a, Ty> {
/// Should only be different from args.len() when c_variadic is true.
/// This can be used to know whether an argument is variadic or not.
pub fixed_count: u32,
/// The calling convention of this function.
pub conv: Conv,
/// Indicates if an unwind may happen across a call to this function.
pub can_unwind: bool,
}