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

[Matt Arsenault via llvm-commits]

https://github.com/arsenm requested changes to this pull request.

I don't think this is really a solution to codegen dying on oversized arrays. The underlying issue still exists regardless of whether InstCombine cleans up constant sized array allocations. 

I think a better fix would be to adjust codegen to treat oversized allocations like dynamic stack allocations 

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