/// <summary>
/// Renames all variables in a block to use their SSA names
/// </summary>
/// <param name="n">Block to rename</param>
public void RenameBlock(Block n)
{
var wasonentry = new Dictionary <Identifier, Identifier>(rename);
// Rename variables in all blocks except the starting block which
// only contains dummy 'def' variables.
if (n != n.Procedure.EntryBlock)
{
foreach (Statement stm in n.Statements)
{
stmCur = stm;
stmCur.Instruction = stmCur.Instruction.Accept(this);
}
if (n == n.Procedure.ExitBlock && this.addUseInstructions)
{
AddUseInstructions(n);
}
}
// Rename arguments to phi functions in successor blocks.
bool [] visited = new bool[proc.ControlGraph.Blocks.Count];
foreach (Block y in n.Succ)
{
for (int j = 0; j < y.Pred.Count; ++j)
{
if (y.Pred[j] == n && !visited[ssa.RpoNumber(y)])
{
visited[ssa.RpoNumber(y)] = true;
// For each phi function in y...
foreach (Statement stm in y.Statements.Where(s => s.Instruction is PhiAssignment))
{
var newPhi = newPhiStatements.Contains(stm);
stmCur = stm;
PhiAssignment phi = (PhiAssignment)stmCur.Instruction;
PhiFunction p = phi.Src;
// replace 'n's slot with the renamed name of the variable.
p.Arguments[j] =
NewUse((Identifier)p.Arguments[j], stm, newPhi);
}
}
}
}
foreach (Block c in ssa.DomGraph.ReversePostOrder.Keys)
{
if (c != proc.EntryBlock && ssa.DomGraph.ImmediateDominator(c) == n)
{
RenameBlock(c);
}
}
rename = wasonentry;
}
private void MarkDefined(Identifier eDef)
{
SsaIdentifier sid;
var idDef = eDef as Identifier;
if (idDef != null && ssa.Identifiers.TryGetValue(idDef, out sid))
{
// If we've seen this identifier before, use its
// original name.
eDef = sid.OriginalIdentifier;
}
var dict = defVars[ssa.RpoNumber(block)];
byte bits;
dict.TryGetValue(eDef, out bits);
dict[eDef] = (byte)(bits | (BitDefined | BitDeadIn));
if (!inDefinitions.Contains(eDef))
{
inDefinitions.Add(eDef);
definitions.Add(eDef);
}
}
private HashSet <Statement> PlacePhiFunctions()
{
HashSet <Statement> phiStatements = new HashSet <Statement>();
var defVars = LocateAllDefinedVariables(AOrig);
MarkTemporariesDeadIn(AOrig);
// For each defined variable in block n, collect the places where it is defined
foreach (var a in defVars)
{
// Create a worklist W of all the blocks that define a.
var W = new WorkList <Block>();
foreach (Block b in SsaState.DomGraph.ReversePostOrder.Keys)
{
byte bits;
AOrig[SsaState.RpoNumber(b)].TryGetValue(a, out bits);
if ((bits & BitDefined) != 0)
{
W.Add(b);
}
}
Block n;
while (W.GetWorkItem(out n))
{
foreach (Block y in SsaState.DomGraph.DominatorFrontier(n))
{
// Only add phi functions if there is no
// phi already and variable is not deadIn.
var dict = AOrig[SsaState.RpoNumber(y)];
byte bits;
dict.TryGetValue(a, out bits);
if ((bits & (BitHasPhi | BitDeadIn)) == 0)
{
bits |= BitHasPhi;
dict[a] = bits;
var stm = InsertPhiStatement(y, a);
phiStatements.Add(stm);
if ((bits & BitDefined) == 0)
{
W.Add(y);
}
}
}
}
}
return(phiStatements);
}
/// <summary>
/// Temporary variables are never live-in, so we avoid getting phi
/// functions all over the place by marking them explicitly as dead-in.
/// </summary>
/// <param name="def"></param>
private void MarkTemporariesDeadIn(Dictionary <Expression, byte>[] def)
{
foreach (var block in proc.ControlGraph.Blocks)
{
int iBlock = SsaState.RpoNumber(block);
foreach (Identifier id in proc.Frame.Identifiers.Where(id => id.Storage is TemporaryStorage))
{
byte bits;
if (!def[iBlock].TryGetValue(id, out bits))
{
bits = 0;
}
def[iBlock][id] = (byte)(bits | BitDeadIn);
}
}
}
