`asm!` xmm16-31 register usage is reported as zmm on i686 targets in diagnostic

Code

pub fn foo() {
    unsafe {
        std::arch::asm!(
            "",
            lateout("xmm0") _,
            lateout("xmm8") _,
            lateout("xmm16") _,
            )
    }
}

Current output

error: cannot use register `xmm8`: register is only available on x86_64
 --> <source>:6:13
  |
6 |             lateout("xmm8") _,
  |             ^^^^^^^^^^^^^^^^^

error: cannot use register `zmm16`: register is only available on x86_64
 --> <source>:7:13
  |
7 |             lateout("xmm16") _,
  |             ^^^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors

Desired output

error: cannot use register `xmm8`: register is only available on x86_64
 --> <source>:6:13
  |
6 |             lateout("xmm8") _,
  |             ^^^^^^^^^^^^^^^^^

error: cannot use register `xmm16`: register is only available on x86_64
 --> <source>:7:13
  |
7 |             lateout("xmm16") _,
  |             ^^^^^^^^^^^^^^^^^^

error: aborting due to 2 previous errors

Rationale and extra context

Registers xmm8-xmm31 are unavailable on 32-bit x86 targets. However, the inline assembly error message reports xmm16 - xmm31 as zmm in the diagnostics (xmm8 - xmm15 are reported as xmm).

This isn't technically wrong due to the way x86 registers are laid out, but a confusing and unnecessary difference in the diagnostic.

Reproduced with i686-pc-windows-msvc and i686-unknown-linux-gnu.

Other cases

Rust Version

rustc 1.99.0-nightly (d0babd8b6 2026-07-15)
binary: rustc
commit-hash: d0babd8b6b05ef9bb65d42f928cef4129d64cf65
commit-date: 2026-07-15
host: x86_64-unknown-linux-gnu
release: 1.99.0-nightly
LLVM version: 22.1.8

Anything else?

No response