[llvm] [LLVM][Triple] Add an argument to specify canonical form to `Triple::normalize` (PR #122935)

[Shilei Tian via llvm-commits]

shiltian wrote:

> What if I ask for a 4-tuple, and the code produces a 5-tuple? Right now, i think I get a 5-tuple?

Yes.

> It's not clear what the code should do here. This seems like an oversight in working out what you intend.

I'm not sure what we should do here, but my second thought would be to cut it to the asked form.

> Are you sure that the items in the 4-/5-tuples are in their correct locations? I'm not sure you can just add unknown at the end, but I could be wrong.

The code to expand `Components` is at the end of the function. At that moment all the other identifiers have been at the right location. I think It is safe to expand the array and add `unknown` here.

> I'd like to see a lot more testing with real triples, not totally fake ones. That would probably answer whether the right thing is happening in the latter case with a lot more certainty.

I can definitely do that.

https://github.com/llvm/llvm-project/pull/122935