[llvm-dev] TableGen pseudo lowering

[Anton Korobeynikov via llvm-dev]

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?
>
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--
With best regards, Anton Korobeynikov
Department of Statistical Modelling, Saint Petersburg State University