message: Use the output finder to find the previous input
diff: @@ -13,15 +13,16 @@ FindInstructionInput(const TensorMap& map,
  const HloInstruction* inst,
  int64 input,
  int64 n) {
  - auto it = map.find(std::make_pair(inst->operand(input)->name(),n));
  - if (it == map.end()) {
  + const HloInstruction* operand = inst->operand(input);
  + std::vector<poplar::Tensor> outputs = FindInstructionOutputs(map, operand);
  + if (outputs.size() == 0) {
  return port::Status(port::error::UNKNOWN,
  port::StrCat("[Poplar] Couldn't find input ",
  input,
  " for ",
  inst->name()));
  }
  - return it->second;
  + return outputs[0];
  }
  std::vector<poplar::Tensor>
  