62d1a080e6
Building on top of https://github.com/llvm/llvm-project/pull/148817, introduce a new abstract LastActiveLane opcode that gets lowered to Not(Mask) → FirstActiveLane(NotMask) → Sub(result, 1). When folding the tail, update all extracts for uses outside the loop the extract the value of the last actice lane. See also https://github.com/llvm/llvm-project/issues/148603 PR: https://github.com/llvm/llvm-project/pull/149042