ced813fec0
Re-land PR #71840 (Rework MIR drop tree lowering) PR https://github.com/rust-lang/rust/pull/71840 was reverted in https://github.com/rust-lang/rust/pull/72989 to fix an LLVM error (https://github.com/rust-lang/rust/issues/72470). That LLVM error no longer occurs with the recent upgrade to LLVM 11 (https://github.com/rust-lang/rust/pull/73526), so let's try re-landing this PR. I've cherry-picked the commits from the original PR (with the exception of the commit blessing test output), making as few modifications as possible. I addressed the rebase fallout in separate commits on top of those. r? `@matthewjasper`