Causes LLVM Error when used in an executable that gets compiled with "+soft-float"

Hi there! I discovered this error originally in the fontdue crate (https://github.com/mooman219/fontdue/issues/98#issuecomment-1011092396) and created a Rust bug report yesterday (https://github.com/rust-lang/rust/issues/92760). In the meantime, I found out that the error originates in this library, which is a dependency of fontdue.

Minimal example to reproduce:

fn main() {
    let _book_reviews = hashbrown::HashMap::<(), ()>::new();
}

Compile with $ cargo rustc --bin bug -- -C target-feature=+soft-float,-sse,-sse2,-x87
Causes a broken compilation and LLVM ERROR: Do not know how to split this operator's operand!

The bug happens with multiple Rust versions, stable and nightly.

I try to further enclose the actual problem and trace it down to a specific Rust pattern or so. Maybe there will be an easy way to work-a-round this bug in this crate (maybe via a cargo feature) until this bug gets closed in Rustc or LLVM?

Start with the minimal HashMap example in the issue and run the given cargo rustc command using the listed target features. Compare the failure across Rust versions and review the linked fontdue and Rust reports to determine whether hashbrown-specific behavior is involved. Done means the failure is isolated to a reproducible hashbrown issue or a documented workaround is identified.