private static unsafe Jsm.ExecutableSegment MakeScript(Operation *operation, UInt16 count)
{
List <JsmInstruction> instructions = new List <JsmInstruction>(count / 2);
LabeledStack stack = new LabeledStack();
LabelBuilder labelBuilder = new LabelBuilder(count);
for (Int32 i = 0; i < count; i++)
{
Jsm.Opcode opcode = operation->Opcode;
Int32 parameter = operation->Parameter;
operation++;
stack.CurrentLabel = i;
IJsmExpression expression = Jsm.Expression.TryMake(opcode, parameter, stack);
if (expression != null)
{
stack.Push(expression);
continue;
}
JsmInstruction instruction = JsmInstruction.TryMake(opcode, parameter, stack);
if (instruction != null)
{
labelBuilder.TraceInstruction(i, stack.CurrentLabel, new IndexedInstruction(instructions.Count, instruction));
instructions.Add(instruction);
continue;
}
throw new NotSupportedException(opcode.ToString());
}
if (stack.Count != 0)
{
throw new InvalidProgramException("Stack unbalanced.");
}
if (!(instructions.First() is LBL))
{
throw new InvalidProgramException("Script must start with a label.");
}
if (!(instructions.Last() is IRET))
{
throw new InvalidProgramException("Script must end with a return.");
}
// Switch from opcodes to instructions
HashSet <Int32> labelIndices = labelBuilder.Commit();
// Merge similar instructions
instructions = InstructionMerger.Merge(instructions, labelIndices);
// Combine instructions to logical blocks
IReadOnlyList <Jsm.IJsmControl> controls = Jsm.Control.Builder.Build(instructions);
// Arrange instructions by segments and return root
return(Jsm.Segment.Builder.Build(instructions, controls));
}
private void FormatBranch(StringBuilder sb, Segment range)
{
sb.AppendLine("{");
for (Int32 i = range.From + 1; i < range.To; i++)
{
JsmInstruction instruction = _instructions[i];
sb.Append('\t').AppendLine(instruction.ToString());
}
sb.AppendLine("}");
}
public static List <JsmInstruction> Merge(List <JsmInstruction> instructions, HashSet <Int32> labelIndices)
{
List <JsmInstruction> result = new List <JsmInstruction>(instructions.Count);
for (Int32 i = 0; i < instructions.Count; i++)
{
JsmInstruction instruction = instructions[i];
result.Add(instruction);
if (labelIndices.Contains(i))
{
continue;
}
if (!(instructions[i] is JPF newJpf))
{
continue;
}
if (i + 1 < instructions.Count && instructions[i + 1] is JMP nextJmp)
{
newJpf.Inverse(nextJmp);
}
if (!(result[result.Count - 2] is JPF oldJpf))
{
continue;
}
if (oldJpf.Index != newJpf.Index)
{
continue;
}
Int32 currentIndex = result.LastIndex();
oldJpf.Union(newJpf);
result.RemoveLast();
oldJpf.Index--;
for (Int32 k = 0; k < instructions.Count; k++)
{
if (instructions[k] is IJumpToInstruction jmp && jmp.Index >= currentIndex && jmp != oldJpf)
{
jmp.Index--;
}
}
}
return(result);
}
public override String ToString()
{
StringBuilder sb = new StringBuilder();
sb.Append("while(");
sb.Append((JPF)_instructions[_segment.From]);
sb.AppendLine(")");
sb.AppendLine("{");
for (Int32 i = _segment.From + 1; i < _segment.To; i++)
{
JsmInstruction instruction = _instructions[i];
sb.Append('\t').AppendLine(instruction.ToString());
}
sb.AppendLine("}");
return(base.ToString());
}
public IndexedInstruction(Int32 index, JsmInstruction instruction)
{
Index = index;
Instruction = instruction;
}