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Erik Eckstein
541664237c
The pass merges to adjacent borrow scopes in a basic block. ``` %2 = begin_borrow %1 use(%2) end_borrow %2 ... %6 = begin_borrow %1 use(%6) end_borrow %6 ``` -> ``` %2 = begin_borrow %1 use(%2) ... use(%2) end_borrow %2 ``` This helps other optimizations, like common-subexpression-elimination, because the borrow liveranges are larger and not split.