Reland #171963, #172639 and #173444, they are reverted in 86b9f90b9574b3a7d15d28a91f6316459dcfa046 because of introducing non-determinism in compiles. The non-determinism has been fixed in 9b8addffa70cee5b2acc5454712d9cf78ce45710.
br i1 undef
JumpThreading