[Bug target/106723] Unreplaced mode/code attributes in aarch64/arm backends

[rearnsha at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106723

--- Comment #3 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
I think we should error if the name matches some iteration values, but not
others.  If <foo> is valid in the assembler output 'as-is' then it's bad form
to have an attribute that overloads this - and the fix is easy: rename the
iterator attribute.