Simonas Kazlauskas 73b221a686 abi: add a rust-preserve-none calling convention
This is the conceptual opposite of the rust-cold calling convention and
is particularly useful in combination with the new `explicit_tail_calls`
feature.

For relatively tight loops implemented with tail calling (`become`) each
of the function with the regular calling convention is still responsible
for restoring the initial value of the preserved registers. So it is not
unusual to end up with a situation where each step in the tail call loop
is spilling and reloading registers, along the lines of:

    foo:
        push r12
        ; do things
        pop r12
        jmp next_step

This adds up quickly, especially when most of the clobberable registers
are already used to pass arguments or other uses.

I was thinking of making the name of this ABI a little less LLVM-derived
and more like a conceptual inverse of `rust-cold`, but could not come
with a great name (`rust-cold` is itself not a great name: cold in what
context? from which perspective? is it supposed to mean that the
function is rarely called?)
2026-01-24 19:23:17 +02:00
2025-12-25 10:38:05 +01:00
2025-01-24 13:23:22 -08:00
2025-10-27 17:17:57 +02:00
2026-01-03 20:13:41 +05:30
2025-10-02 10:23:35 +03:00
2025-02-07 20:18:21 +01:00

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rust-analyzer is a language server that provides IDE functionality for writing Rust programs. You can use it with any editor that supports the Language Server Protocol (VS Code, Vim, Emacs, Zed, etc).

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