[PATCH] D93298: [RISCV] add the MC layer support of Zfinx extension

Fraser Cormack via Phabricator via cfe-commits cfe-commits at lists.llvm.org
Fri Sep 24 08:53:36 PDT 2021


frasercrmck added a comment.

In D93298#3014160 <https://reviews.llvm.org/D93298#3014160>, @jrtc27 wrote:

> The amount of duplication here really depresses me and is only going to get worse once codegen is added, but TableGen isn't able to have operands that use different register classes based on even HwMode, that I know of, and whilst you could make use of multi classes to generate both versions of the instructions you can't easily do that for patterns, so I don't know what the right answer is.

Do we know if it's possible to teach TableGen how to do that? This extension seems like a good reason to implement such a feature as the duplication really is unfortunate.

I thought that `MCOperandInfo` may be an issue but there's already dynamic lookup there to support `isLookupPtrRegClass`.


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