/// <summary>
/// Group input into a set of blocks that can be later arbitraliby schufled.
/// The method adds necessary branches to make control flow between blocks
/// explicit and thus order independent.
/// </summary>
void SplitToBasicBlocks(ILBlock block)
{
List <ILNode> basicBlocks = new List <ILNode>();
ILLabel entryLabel = block.Body.FirstOrDefault() as ILLabel ?? new ILLabel()
{
Name = "Block_" + (nextLabelIndex++)
};
ILBasicBlock basicBlock = new ILBasicBlock();
basicBlocks.Add(basicBlock);
basicBlock.Body.Add(entryLabel);
block.EntryGoto = new ILExpression(ILCode.Br, entryLabel);
if (block.Body.Count > 0)
{
if (block.Body[0] != entryLabel)
{
basicBlock.Body.Add(block.Body[0]);
}
for (int i = 1; i < block.Body.Count; i++)
{
ILNode lastNode = block.Body[i - 1];
ILNode currNode = block.Body[i];
// Start a new basic block if necessary
if (currNode is ILLabel ||
currNode is ILTryCatchBlock || // Counts as label
lastNode.IsConditionalControlFlow() ||
lastNode.IsUnconditionalControlFlow())
{
// Try to reuse the label
ILLabel label = currNode as ILLabel ?? new ILLabel()
{
Name = "Block_" + (nextLabelIndex++).ToString()
};
// Terminate the last block
if (!lastNode.IsUnconditionalControlFlow())
{
// Explicit branch from one block to other
basicBlock.Body.Add(new ILExpression(ILCode.Br, label));
}
// Start the new block
basicBlock = new ILBasicBlock();
basicBlocks.Add(basicBlock);
basicBlock.Body.Add(label);
// Add the node to the basic block
if (currNode != label)
{
basicBlock.Body.Add(currNode);
}
}
else
{
basicBlock.Body.Add(currNode);
}
}
}
block.Body = basicBlocks;
return;
}
public static bool IsUnconditionalControlFlow(this ILNode node)
{
ILExpression expr = node as ILExpression;
return(expr != null && expr.Code.IsUnconditionalControlFlow());
}
public static bool Match(this ILNode node, ILCode code)
{
ILExpression expr = node as ILExpression;
return(expr != null && expr.Prefixes == null && expr.Code == code);
}
public static bool MatchStloc(this ILNode node, ILVariable expectedVar, out ILExpression expr)
{
ILVariable v;
return(node.Match(ILCode.Stloc, out v, out expr) && v == expectedVar);
}
public static bool MatchLdloca(this ILNode node, ILVariable expectedVar)
{
ILVariable v;
return(node.Match(ILCode.Ldloca, out v) && v == expectedVar);
}
public static bool MatchThis(this ILNode node)
{
ILVariable v;
return(node.Match(ILCode.Ldloc, out v) && v.IsParameter && v.OriginalParameter.Index == -1);
}