[llvm] [GVN] Permit load PRE to happen in more cases (PR #79324)

[David Sherwood via llvm-commits]

david-arm wrote:

Hi @nikic and @paulwalker-arm, unlike Phabricator I can't "Plan Changes" or "Request Changes" on my own PR, so I can only leave a comment here.

Downstream I have a patch that significantly restricts the maximum number of instructions we are willing to walk in total to just the amount that triggers the optimisation in omnetpp. However, it seems that this still causes significant compile-time regressions and probably the cost of doing this analysis outweighs the benefits. I'll put this PR on hold for now.

https://github.com/llvm/llvm-project/pull/79324