/// <summary>
/// Performs stage specific processing on the compiler context.
/// </summary>
public void Run()
{
bool remove = false;
foreach (BasicBlock block in BasicBlocks)
{
for (Context ctx = new Context(InstructionSet, block); !ctx.EndOfInstruction; ctx.GotoNext())
{
if (ctx.Instruction is IR.MoveInstruction || ctx.Instruction is CIL.StlocInstruction)
{
if (ctx.Operand1 is ConstantOperand)
{
// HACK: We can't track a constant through a register, so we keep those moves
if (ctx.Result is StackOperand)
{
Debug.Assert(ctx.Result.Definitions.Count == 1, @"Operand defined multiple times. Instruction stream not in SSA form!");
ctx.Result.Replace(ctx.Operand1, InstructionSet);
remove = true;
}
}
}
else if (ctx.Instruction is IR.PhiInstruction)
{
IR.PhiInstruction phi = (IR.PhiInstruction)ctx.Instruction;
ConstantOperand co = ctx.Operand2 as ConstantOperand;
List <BasicBlock> blocks = ctx.Other as List <BasicBlock>; // FIXME PG / ctx has moved
if (co != null && blocks.Count == 1)
{
// We can remove the phi, as it is only defined once
// HACK: We can't track a constant through a register, so we keep those moves
if (!ctx.Result.IsRegister)
{
Debug.Assert(ctx.Result.Definitions.Count == 1, @"Operand defined multiple times. Instruction stream not in SSA form!");
ctx.Result.Replace(co, InstructionSet);
remove = true;
}
}
}
// Shall we remove this instruction?
if (remove)
{
ctx.Remove();
remove = false;
}
}
}
}
private void MergePhiInstructions(BasicBlock block, BasicBlock caller, IDictionary <StackOperand, StackOperand> liveIn)
{
for (Context ctx = new Context(InstructionSet, block); !ctx.EndOfInstruction; ctx.GotoNext())
{
IR.PhiInstruction phi = ctx.Instruction as IR.PhiInstruction;
if (phi != null && liveIn.ContainsKey(ctx.Result as StackOperand))
{
StackOperand value = liveIn[ctx.Result as StackOperand];
if (!IR.PhiInstruction.Contains(ctx, value) && (ctx.Result as StackOperand).Version != value.Version)
{
IR.PhiInstruction.AddValue(ctx, caller, value);
}
}
}
}
