/// <summary>
/// Simplifies the CFG of the given implementation impl by merging each
/// basic block with a single predecessor into that predecessor if the
/// predecessor has a single successor. If a uniformity analyser is
/// being used then blocks will only be merged if they are both uniform
/// or both non-uniform
/// </summary>
public static void MergeBlocksIntoPredecessors(Program prog, Implementation impl, UniformityAnalyser uni)
{
var blockGraph = prog.ProcessLoops(impl);
var predMap = new Dictionary<Block, Block>();
foreach (var block in blockGraph.Nodes)
{
try
{
var pred = blockGraph.Predecessors(block).Single();
if (blockGraph.Successors(pred).Single() == block &&
(uni == null ||
(uni.IsUniform(impl.Name, pred) && uni.IsUniform(impl.Name, block)) ||
(!uni.IsUniform(impl.Name, pred) && !uni.IsUniform(impl.Name, block))))
{
Block predMapping;
while (predMap.TryGetValue(pred, out predMapping))
pred = predMapping;
pred.Cmds.AddRange(block.Cmds);
pred.TransferCmd = block.TransferCmd;
impl.Blocks.Remove(block);
predMap[block] = pred;
}
// If Single throws an exception above (i.e. not exactly one pred/succ), skip this block.
}
catch (InvalidOperationException) { }
}
}
