[llvm] [DAG] computeKnownFPClass - add ISD::EXTRACT_SUBVECTOR/INSERT_SUBVECTOR handling. (PR #190378)

[Simon Pilgrim via llvm-commits]

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+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
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RKSimon wrote:

You might be able to add these to the existing combine-is_fpclass.ll file

Ideally the base tests should be added as the base commit in the PR so that the codegen change is clear.

https://github.com/llvm/llvm-project/pull/190378