905f2d1ecb
The testcase was delta-reduced from an LTO build with sanitizer coverage and the MIR tail duplication pass caused a machine basic block to become unreachable in MIR. This caused the MBB to be invisible to the reverse post-order traversal used to initialize the MBB <-> RPONumber lookup tables. rdar://97226240 Differential Revision: https://reviews.llvm.org/D130999