/// <summary>
/// Lays out all parameters of the method.
/// </summary>
private void LayoutParameters()
{
var parameters = new List <Operand>();
int offset = 0;
if (MethodCompiler.Method.HasThis || MethodCompiler.Method.HasExplicitThis)
{
++offset;
}
for (int i = 0; i < MethodCompiler.Method.Signature.Parameters.Count + offset; ++i)
{
var parameter = MethodCompiler.GetParameterOperand(i);
parameters.Add(parameter);
}
int returnSize = 0;
if (TypeLayout.IsCompoundType(MethodCompiler.Method.Signature.ReturnType))
{
returnSize = TypeLayout.GetTypeSize(MethodCompiler.Method.Signature.ReturnType);
}
int size = LayoutVariables(parameters, CallingConvention, CallingConvention.OffsetOfFirstParameter + returnSize, false);
MethodCompiler.StackLayout.StackParameterSize = size;
MethodCompiler.TypeLayout.SetMethodParameterStackSize(MethodCompiler.Method, size);
}
/// <summary>
/// Adds PHI functions for all ref/out parameters of the method being compiled.
/// </summary>
private void AddPhiFunctionsForOutParameters()
{
Dictionary <StackOperand, StackOperand> liveIn = null;
// Retrieve the well known epilogue block
BasicBlock epilogue = FindBlock(Int32.MaxValue);
Debug.Assert(epilogue != null, "Method doesn't have epilogue block?");
Context ctxEpilogue = new Context(InstructionSet, epilogue);
ctxEpilogue.GotoLast();
// Iterate all parameter definitions
foreach (RuntimeParameter rp in MethodCompiler.Method.Parameters)
{
// Retrieve the stack operand for the parameter
StackOperand paramOp = (StackOperand)MethodCompiler.GetParameterOperand(rp.Position - 1);
// Only add a PHI if the runtime parameter is out or ref...
if (rp.IsOut || (paramOp.Type is RefSigType || paramOp.Type is PtrSigType))
{
ctxEpilogue.AppendInstruction(IR.Instruction.PhiInstruction, paramOp);
if (liveIn == null)
{
liveIn = new Dictionary <StackOperand, StackOperand> ();
}
liveIn.Add(paramOp, paramOp);
}
}
// Save the in versions to force a merge later
if (liveIn != null)
{
_liveness[epilogue.Sequence] = liveIn;
}
}
/// <summary>
/// Performs stage specific processing on the compiler context.
/// </summary>
public void Run()
{
_dominanceProvider = (IDominanceProvider)MethodCompiler.GetPreviousStage(typeof(IDominanceProvider));
Debug.Assert(_dominanceProvider != null, "SSA Conversion requires a dominance provider.");
if (_dominanceProvider == null)
{
throw new InvalidOperationException("SSA Conversion requires a dominance provider.");
}
// Allocate space for live outs
_liveness = new IDictionary <StackOperand, StackOperand> [BasicBlocks.Count];
// Retrieve the dominance frontier Blocks
_dominanceFrontierBlocks = _dominanceProvider.GetDominanceFrontier();
// Add ref/out parameters to the epilogue block to have uses there...
AddPhiFunctionsForOutParameters();
// Transformation worklist
Queue <WorkItem> workList = new Queue <WorkItem> ();
/* Move parameter operands into the dictionary as version 0,
* because they are live at entry and maybe referenced. Anyways, an
* assignment to a parameter is also SSA related.
*/
IDictionary <StackOperand, StackOperand> liveIn = new Dictionary <StackOperand, StackOperand> (s_comparer);
int i = 0;
if (MethodCompiler.Method.Signature.HasThis)
{
StackOperand param = (StackOperand)MethodCompiler.GetParameterOperand(0);
liveIn.Add(param, param);
i++;
}
for (int j = 0; j < MethodCompiler.Method.Parameters.Count; j++)
{
StackOperand param = (StackOperand)MethodCompiler.GetParameterOperand(i + j);
liveIn.Add(param, param);
}
// Start with the very first block
workList.Enqueue(new WorkItem(BasicBlocks[0], null, liveIn));
// Iterate until the worklist is empty
while (workList.Count != 0)
{
// Remove the block From the queue
WorkItem workItem = workList.Dequeue();
// Transform the block
BasicBlock block = workItem.block;
bool schedule = TransformToSsaForm(new Context(InstructionSet, block), workItem.caller, workItem.liveIn, out liveIn);
_liveness[block.Sequence] = liveIn;
if (schedule)
{
// Add all branch targets to the work list
foreach (BasicBlock next in block.NextBlocks)
{
// Only follow backward branches, if we've redefined a variable
// this may force us to reinsert a PHI function in a block we
// already have completed processing on.
workList.Enqueue(new WorkItem(next, block, liveIn));
}
}
}
}
