scratch_index     391 src/LoopCarry.cpp                 Expr scratch_idx = scratch_index(i, orig_load->type);
scratch_index     407 src/LoopCarry.cpp                                                scratch_index(i-1, orig_load->type),
scratch_index     434 src/LoopCarry.cpp                 Expr scratch_idx = scratch_index(i, initial_scratch_values[i].type());