[llvm-dev] TableGen pseudo lowering

[Paul C. Anagnostopoulos via llvm-dev]

Can you give an example of the property splitting issue?

At 9/26/2020 03:34 AM, Anton Korobeynikov wrote:
>Paul,
>
>Absolutely. This may reduce the amount of hand-written code for
>pseudo-expansion in the backends in general. However, there are
>caveats as in many cases additional properties need to be transferred
>as well and "splitted" between these instructions. I don't have a good
>solution for this.
>
>
>On Fri, Sep 25, 2020 at 7:48 PM Paul C. Anagnostopoulos via llvm-dev
><llvm-dev at lists.llvm.org> wrote:
>>
>> The TableGen PseudoLoweringEmitter backend is responsible for lowering pseudo-instructions to real machine instructions. In the code is this comment:
>>
>> // FIXME: This pass currently can only expand a pseudo to a single instruction.
>> //        The pseudo expansion really should take a list of dags, not just
>> //        a single dag, so we can do fancier things.
>>
>> Does anyone think that enhancing it to expand to multiple instructions is worth the effort?