GetBasicBlockLinearIrInstructions(CilBasicBlock basicBlock)
{
var result = new List <LinearIrInstruction>();
foreach (var instruction in basicBlock.Instructions)
{
result.Add(GetLinearIrInstructionFrom(instruction));
}
return(result);
}
/// <summary>
/// Recursive implementation of a DFS traversal on the control flow graph.
/// Recursion enables us to easily save the number of elements on the
/// evaluation stack before traversing a path. This way we know the
/// state of the evaluation stack after the control flow path is examined,
/// and we can move on with a valid evaluation stack to the other paths.
/// </summary>
/// <param name="basicBlock"> The starting basic block </param>
/// <param name="visited">
/// A map of visited nodes to their respective linear ir code string
/// </param>
private void RecursiveDFS(CilBasicBlock basicBlock)
{
visited.Add(basicBlock, GetBasicBlockLinearIrInstructions(basicBlock));
int evaluationStackSizeSnapshot = evaluationStackSize;
foreach (var outBasicBlock in basicBlock.OutBasicBlocks)
{
evaluationStackSize = evaluationStackSizeSnapshot;
if (!visited.ContainsKey(outBasicBlock))
{
RecursiveDFS(outBasicBlock);
}
}
}
/// <summary>
/// Performs a pass over the method body instructions and identifies the basic blocks.
/// This pass essentially generates the nodes of the graph.
/// </summary>
private void ConstructBasicBlocks()
{
int basicBlockId = 0;
var currentBasicBlock = new CilBasicBlock(basicBlockId);
foreach (var instruction in instructions)
{
currentBasicBlock.Instructions.Add(instruction);
// Update the dictionary for the branch target instructions.
if (branchTargetInstructionDictionary.ContainsKey(instruction))
{
branchTargetInstructionDictionary[instruction] = currentBasicBlock;
}
if (instruction.Next == null ||
branchTargetInstructionDictionary.ContainsKey(instruction.Next) || // Next BB starts at branch target.
instruction.IsControlFlowInstruction()) // BB ends at branch.
{
// When we reach the end of the Basic block
// we add it to the result list.
BasicBlocks.Add(currentBasicBlock);
currentBasicBlock = new CilBasicBlock(++basicBlockId);
}
}
}
