[llvm] [LLVM][Tablegen] Add Default arguments support for Intrinsics in TableGen (PR #198557)

[Rahul Joshi via llvm-commits]

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jurahul wrote:

for witdth < 64, we don't know the signedness of the type, so should only accept values that are >= 0? For example, for i0, we will only accept values 0 -255, or 0x0 - 0xff.

https://github.com/llvm/llvm-project/pull/198557