[llvm] [SimplifyCFG] Simplify conditional branches on const icmp eq's (PR #73334)

[via llvm-commits]

yonillasky wrote:

So ... the suggested alternative is to replace all calls to `DeleteDeadBlock` with a new function that has the same semantics, but also lets us act upon 1-input PHIs being decayed into constants?


https://github.com/llvm/llvm-project/pull/73334