[llvm] [llvm-exegesis] [AArch64] Resolving "not all operands are initialized by snippet generator" (PR #142529)

[Lakshay Kumar via llvm-commits]

lakshayk-nv wrote:

> @lakshayk-nv: before we merge this, can you see if you can make the subject and description a bit more concrete with info on which opcodes are now supported because this patch has been a bit of journey.
>>
Updated the PR description and comments in code, including current state of this PR for the given error with the opcodes that we add support, findings from `OPERAND_UNKNOWN` hacky fix and its limitation and correct way to add rest support for un-init operands error.

This should cover everything, shoot any left out work if any.
Thanks !

https://github.com/llvm/llvm-project/pull/142529