[clang] [clang-tools-extra] [compiler-rt] [llvm] [X86] AMD Zen 6 Initial enablement (PR #179150)

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ganeshgit wrote:

> Mainly minor tidyup comments - it'd be much better if the BMM work was in a separate patch to the znver6 work - some BMM ref docs would be good as all I have to go off is the gcc patches. We have enough ISD::BITREVERSE functionality now that I don't see any need for the BITREV builtins/intrinsics.

Agreed. Will split the patch into two. The BMM doc is available as https://docs.amd.com/v/u/en-US/69192-PUB.

BITREVERSE includes all integer types whereas BITREVB is byte granular. So, thought of having it separately. 

https://github.com/llvm/llvm-project/pull/179150