static private ConditionStatementBlock Detect(Instruction first, Instruction last)
{
Instruction current = null;
for (var instruction = first; instruction != last.Next && instruction != null; instruction = instruction.Next)
{
if (ConditionalBranch_OpCodes.Contains(instruction.OpCode) && (instruction.Operand as Instruction).Offset > instruction.Offset)
{
current = instruction;
break;
}
}
if (current == null)
{
return(null);
}
Instruction next = current.Operand as Instruction;
var lastOffset = last.Offset;
if (lastOffset < current.Offset ||
lastOffset < current.Next.Offset ||
lastOffset < next.Previous.Offset)
{
return(null);
}
return(new ConditionStatementBlock(
new CodeBlock(first, current),
new CodeBlock(current.Next, next.Previous)
));
}
static public bool Detect(CodeBlock block, out StatementStructure statementStructure)
{
List <OpCode> brs = new List <OpCode> {
OpCodes.Br_S, OpCodes.Br
};
statementStructure = null;
if (!ConditionalBranch_OpCodes.Contains(block.first.OpCode))
{
return(false);
}
var conditionStatementBlock = Detect(block.first, block.last);
if (conditionStatementBlock == null)
{
return(false);
}
List <ConditionStatementBlock> blocks = new List <ConditionStatementBlock>();
blocks.Add(conditionStatementBlock);
while (true)
{
var next = conditionStatementBlock.body.last.Next;
if (!brs.Contains(next.Previous.OpCode))
{
break;
}
var br = next.Previous as Instruction;
var target = br.Operand as Instruction;
if (target.OpCode == OpCodes.Ret)
{
break;
}
conditionStatementBlock = Detect(next, target.Previous);
if (conditionStatementBlock == null)
{
conditionStatementBlock = new ConditionStatementBlock(null, new CodeBlock(next, target.Previous));
blocks.Add(conditionStatementBlock);
break;
}
var current = blocks[blocks.Count - 1];
blocks[blocks.Count - 1] = new ConditionStatementBlock(
current.condition,
new CodeBlock(current.body.first, current.body.last.Previous)
);
blocks.Add(conditionStatementBlock);
}
CodeBlock all = new CodeBlock(block.first, blocks[blocks.Count - 1].body.last);
statementStructure = new ConditionStatementStructure(all, blocks);
return(true);
}
static public bool Detect(CodeBlock block, out StatementStructure statementStructure)
{
statementStructure = null;
var opCode = block.first.OpCode;
if (opCode != OpCodes.Br && opCode != OpCodes.Br_S)
{
return(false);
}
// maybe loop condition
var target = block.first.Operand as Instruction;
// find next branch instruction (Brtrue, Brtrue_S), which may be a loop tag and an end
Instruction last = null;
{
var tmp = target;
while (tmp != null && !ConditionalBranch_OpCodes.Contains(tmp.OpCode))
{
tmp = tmp.Next;
}
if (tmp == null)
{
return(false);
}
last = tmp;
}
// loop body
if ((last.Operand as Instruction).Previous != block.first)
{
return(false);
}
CodeBlock all = new CodeBlock(block.first, last);
CodeBlock init = null;
CodeBlock condition = new CodeBlock(target, last);
CodeBlock step = null;
CodeBlock body = new CodeBlock(block.first.Next, target.Previous);
statementStructure = new LoopStatementStructure(all, init, condition, step, body);
return(true);
}
