[llvm] [X86] Remove def32 and drop redundant zero extensions after `isel` (PR #225462)

[Akash Manna via llvm-commits]

akash-manna-sky wrote:

> Is #218382 also fixed by #223750. I see the description also mentioned shrinkAndImmediate.

Yes, it is the same all-ones path in `shrinkAndImmediate` with a truncate operand, so #223750 covers #218382 as well. I'll rebase on top of it, drop the guard and the `SDNode` `isDef32` again since the `zext` no longer depends on its operand, and keep the reduced case from #218382 here as a regression test later.


https://github.com/llvm/llvm-project/pull/225462