[llvm] [InstCombine] Avoid Allocating Arrays Too Large For the Target (PR #70980)

[Nikita Popov via llvm-commits]

nikic wrote:

LangRef also isn't clear on what exactly the semantics are around that type size * num elements multiplication -- in what bit width is it performed? What happens on overflow?

We should probably clarify these things, otherwise it's hard to say what the correct behavior is.

https://github.com/llvm/llvm-project/pull/70980