/// <summary>
/// Compute a pre order (ignoring back edges) of the CFG reachable from the entry node
///
/// As a side effect, assigns each block its DF finishing number.
/// </summary>
public static FList /*<BasicBlocks>*/ Compute(ControlFlowGraph cfg)
{
// depth-first search
bool[] markBit = new bool[cfg.BlockCount];
FList result = null;
int DFTime = 0;
// Use a stack to represent the state of the search.
// Each stack element consists of a basic block and the
// the index of the next successor of that block to process.
Stack stack = new Stack();
CfgBlock[] blocks = cfg.Blocks();
CfgBlock start = cfg.Entry;
// invariant: all blocks pushed on the stack are marked.
markBit[start.Index] = true;
stack.Push(new StackElem(start));
while (stack.Count > 0)
{
StackElem elem = (StackElem)stack.Peek();
CfgBlock b = elem.node;
int nextChild = elem.nextChild;
CfgBlock[] normalNodes = cfg.NormalSucc(b);
CfgBlock[] exnNodes = cfg.ExcpSucc(b);
int normalNodesCount = normalNodes.Length;
int exnNodesCount = exnNodes.Length;
// Is there another child to process?
if (nextChild < normalNodesCount + exnNodesCount)
{
// Figure out the actual block.
CfgBlock child;
if (nextChild < normalNodesCount)
{
child = normalNodes[nextChild];
}
else
{
child = exnNodes[nextChild - normalNodesCount];
}
elem.nextChild = nextChild + 1;
// push the child block on to the stack.
if (!markBit[child.Index])
{
markBit[child.Index] = true;
stack.Push(new StackElem(child));
}
}
else
{
// After all children are processed, place the block
// on the result.
stack.Pop();
b.priority = ++DFTime;
result = FList.Cons(b, result);
}
}
return(result);
}
/// <summary>
/// Examines a CFG and removes the stack manipulating instructions by introducing
/// some explicit variables for stack locations. After this transformation, no more
/// Pop, Dup etc.
/// </summary>
/// <param name="cfg">Control Flow Graph that is modified by the transformation.
/// This argument WILL be mutated.</param>
/// <returns>A map that assigns to each block from <c>cfg</c> the stack depth at its
/// beginning. Useful as a pseudo-liveness information.</returns>
public static int[] Process(ControlFlowGraph cfg)
{
StackRemovalTransformation sd = new StackRemovalTransformation(cfg);
StackRemovalVisitor srv = new StackRemovalVisitor();
// should be in order.
foreach (CfgBlock block in cfg.PreOrder) {
int depth = sd.InitialDepthOfBlock(block, cfg);
if (depth < 0) {
continue;
}
// set block starting depth
srv.depth = depth;
StatementList stats = block.Statements;
for(int i = 0, n = stats.Count; i < n; i++) {
stats[i] = (Statement) srv.Visit(stats[i]);
if (cfg.GenericsUse == null) { cfg.GenericsUse = srv.GenericsUse; }
if (cfg.PointerUse == null) { cfg.PointerUse = srv.PointerUse; }
if (srv.SawMissingInfo) { cfg.HasMissingInfo = true; }
}
// push final depth onto successors.
foreach (CfgBlock succ in cfg.NormalSucc(block)) {
sd.PushDepth(succ, srv.depth);
}
}
// finalize stack depth info on each block
foreach (CfgBlock block in cfg.Blocks())
{
int depth = sd.block2depth[block.Index];
// cache depth on block
block.stackDepth = depth;
if (depth < 0) {
// unreachable
// set statementlist to null in case some backward analysis or other code gets to it
if (block.Statements.Count > 0) {
block.Statements = new StatementList(0);
}
}
}
return sd.block2depth;
}
/// <summary>
/// Examines a CFG and removes the stack manipulating instructions by introducing
/// some explicit variables for stack locations. After this transformation, no more
/// Pop, Dup etc.
/// </summary>
/// <param name="cfg">Control Flow Graph that is modified by the transformation.
/// This argument WILL be mutated.</param>
/// <returns>A map that assigns to each block from <c>cfg</c> the stack depth at its
/// beginning. Useful as a pseudo-liveness information.</returns>
public static int[] Process(ControlFlowGraph cfg)
{
StackRemovalTransformation sd = new StackRemovalTransformation(cfg);
StackRemovalVisitor srv = new StackRemovalVisitor();
// should be in order.
foreach (CfgBlock block in cfg.PreOrder)
{
int depth = sd.InitialDepthOfBlock(block, cfg);
if (depth < 0)
{
continue;
}
// set block starting depth
srv.depth = depth;
StatementList stats = block.Statements;
for (int i = 0, n = stats.Count; i < n; i++)
{
stats[i] = (Statement)srv.Visit(stats[i]);
if (cfg.GenericsUse == null)
{
cfg.GenericsUse = srv.GenericsUse;
}
if (cfg.PointerUse == null)
{
cfg.PointerUse = srv.PointerUse;
}
if (srv.SawMissingInfo)
{
cfg.HasMissingInfo = true;
}
}
// push final depth onto successors.
foreach (CfgBlock succ in cfg.NormalSucc(block))
{
sd.PushDepth(succ, srv.depth);
}
}
// finalize stack depth info on each block
foreach (CfgBlock block in cfg.Blocks())
{
int depth = sd.block2depth[block.Index];
// cache depth on block
block.stackDepth = depth;
if (depth < 0)
{
// unreachable
// set statementlist to null in case some backward analysis or other code gets to it
if (block.Statements.Count > 0)
{
block.Statements = new StatementList(0);
}
}
}
return(sd.block2depth);
}
