[llvm] [VPlan] Encode single-scalar-ness of VPInstruction in a field (NFC). (PR #227761)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

> can it be encoded as `VPValue::getSymbolicTypes()`

Hm, so the idea would be to narrow recipes to single-scalars by simply narrowing its operands, and query the single-scalar-ness of recipes by checking if any of the operands are single-scalar? This might be workable in principle, but I think what we currently do is to broadcast all live-ins in wide consumers? We have some ad-hoc code currently to avoid introducing extra broadcasts when narrowing recipes that I really wish we could clean up? I'm not totally sure what kind of benefit we'd get in practice by encoding the single-scalar-ness in live-ins?

https://github.com/llvm/llvm-project/pull/227761