EXPECT_THAT(r_.GetPeakMemory(), FieldsAre(Eq(2), Eq(4)));

  r_.AddUse(/*ioperation=*/2, /*itensor=*/2);
  EXPECT_THAT(r_.GetMemProfile(), ElementsAre(0, 0, 4, 0, 0, 0));
  EXPECT_THAT(r_.GetPeakMemory(), FieldsAre(Eq(2), Eq(4)));

  r_.AddUse(/*ioperation=*/4, /*itensor=*/2);
  EXPECT_THAT(r_.GetMemProfile(), ElementsAre(0, 0, 4, 4, 4, 0));
  EXPECT_THAT(r_.GetPeakMemory(), FieldsAre(Eq(4), Eq(4)));

}

std::tuple<Rematerializer::SizeT, Rematerializer::RematSpec>
Rematerializer::FindBestRemat(const SizeT min_savings, const int begin_len,
                              const int end_len) const {
  const auto peak = GetPeakMemory();
  SizeT best_peak_mem = peak.size;
  RematSpec best_remat = {};

  for (int len = begin_len; len < end_len; ++len) {
    std::vector<std::tuple<SizeT, int, int>> pre_screen;

  // Gives the peak memory location and size after inserting operations
  // according to `remat` (but doesn't actually insert them.)  Ties are broken
  // towards later locations. `remat` must be valid (see above).
  MemSpec GetPeakMemory(const RematSpec& remat = {}) const;

  // Gives memory profile after inserting operations according to `remat` (but
  // doesn't actually insert them). `remat` must be valid (see above).