When multiple dialects share td `#includes` (e.g. `affine` includes
`arith`), each dialect's `*_enum_gen.py` file registers attribute
builders under the same keys, causing "already registered" errors on the
second import; the first commit checks in such a case which currently
fails on main:
```
# | RuntimeError: Attribute builder for 'Arith_CmpFPredicateAttr' is already registered with func: <function _arith_cmpfpredicateattr at 0x78d13cbe9a80>
```
This PR implements a two-pronged fix:
1. Add `allow_existing=True` to `register_attribute_builder` (and the
underlying C++ `registerAttributeBuilder`). When set, silently skips
registration if the key already exists (first-wins semantics). This
handles `EnumInfo`-based builders which have no dialect prefix (e.g.
`AtomicRMWKindAttr`, `Arith_CmpFPredicateAttr`), which may be emitted by
every dialect whose td file includes the defining file;
2. Filter `EnumAttr` builders by `-bind-dialect` in
`EnumPythonBindingGen.cpp` and register them under dialect qualified
keys (`"dialect.AttrName"`). Update `OpPythonBindingGen.cpp` to look up
the same qualified keys for EnumAttr typed op attributes (detected via
`isSubClassOf("EnumAttr")`). Pass `-bind-dialect` from
`AddMLIRPython.cmake`.
This approach incurs no changes to `ir.py` registrations (no "builtin."
prefix), and no manual builder additions to individual dialect Python
files (unlike the previous attempt
https://github.com/llvm/llvm-project/pull/117918).
Note, this PR was "clauded" not "coded".
c3f381ccfe