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	// Subsequent blocks, if any. The number and order depend on the block kind.
	Succs []Edge

	// Inverse of successors.
	// The order is significant to Phi nodes in the block.
	// TODO: predecessors is a pain to maintain. Can we somehow order phi
	// arguments by block id and have this field computed explicitly when needed?
	Preds []Edge

	// A list of values that determine how the block is exited. The number

    AnalyzeRegion(region);
  }

  SideEffectAnalysisInfo(SideEffectAnalysisInfo&&) = default;

  // Returns a vector of ops that are direct control predecessors of `op`,
  // sorted in program order. If `filter` is provided, only predecessors that
  // pass the filter (returning true) will be included.
  const llvm::SmallVector<Operation*, 4>& DirectControlPredecessors(
      Operation* op) const;

  for (auto& entry : control_predecessors_) {
    auto op = entry.getFirst();
    auto& predecessors = entry.getSecond();
    auto& sorted_predecessors = sorted_control_predecessors_[op];
    for (Operation* predecessor : predecessors) {
      sorted_predecessors.push_back(predecessor);
      sorted_control_successors_[predecessor].push_back(op);
    }
  }
  control_predecessors_.clear();

		state.currentState.reset(ourStartState)
	}

	// Zero predecessors
	if len(preds) == 0 {
		if previousBlock != nil {
			state.f.Fatalf("Function %v, block %s with no predecessors is not first block, has previous %s", state.f, b.String(), previousBlock.String())
		}
		// startState is empty
		reset(abt.T{})
		return abt.T{}, blockChanged
	}

	// One predecessor
	l0 := blockLocs[preds[0].ID]
	p0 := l0.endState

	var args []*Value
	for _, a := range target.Args {
		if a != load && a.Block.ID == target.Block.ID {
			args = append(args, a)
		}
	}

	// memPreds contains memory states known to be predecessors of load's
	// memory state. It is lazily initialized.
	var memPreds map[*Value]bool
	for i := 0; len(args) > 0; i++ {
		const limit = 100
		if i >= limit {
			// Give up if we have done a lot of iterations.

	// come right after it.
	after := map[ID][]*Block{}

	// Check each loop header and decide if we want to move it.
	for _, loop := range loopnest.loops {
		b := loop.header
		var p *Block // b's in-loop predecessor
		for _, e := range b.Preds {
			if e.b.Kind != BlockPlain {
				continue
			}
			if loopnest.b2l[e.b.ID] != loop {
				continue
			}
			p = e.b
		}
		if p == nil {
			continue
		}

                // Node must be at the predecessor state before calculating dependencies
                NodeAtState predecessor = new NodeAtState(getPath(), getTargetState().previous());
                dependencies.add(graph.nodeAtState(predecessor));
                // Transition any other nodes that depend on the predecessor state
                dependencies.add(new TransitionDependents(predecessor));
                seenPredecessor = true;

	}
	for _, r := range rules {
		if r.op == "!<" {
			disallowed = append(disallowed, r)
			continue
		}
		for _, def := range r.def {
			if def == "NONE" {
				errorf("NONE cannot be a predecessor")
				continue
			}
			if !g.addNode(def) {
				errorf("multiple definitions for %s", def)
			}
			for _, less := range r.less {
				if less == "NONE" {
					continue
				}

	}
}

// An integrator tracks a position in a utilization function and
// integrates it.
type integrator struct {
	u *mmuSeries
	// pos is the index in u.util of the current time's non-strict
	// predecessor.
	pos int
}

// advance returns the integral of the utilization function from 0 to
// time. advance must be called on monotonically increasing values of
// times.

	}
	return &ssa.FuncLines{Filename: file, StartLineno: start, Lines: lines}, nil
}

// updateUnsetPredPos propagates the earliest-value position information for b
// towards all of b's predecessors that need a position, and recurs on that
// predecessor if its position is updated. B should have a non-empty position.
func (s *state) updateUnsetPredPos(b *ssa.Block) {
	if b.Pos == src.NoXPos {
		s.Fatalf("Block %s should have a position", b)
	}