private static void MoveInward(GotoStatement stmt)
{
AstBlock block = ParentBlock(stmt.Goto);
AstBlock[] path = BackwardsPath(block, ParentBlock(stmt.Label));
for (int index = path.Length - 1; index >= 0; index--)
{
AstBlock child = path[index];
AstBlock last = child;
if (child.Type == AstBlockType.If)
{
// Modify the if condition to allow it to be entered by the goto.
if (!ContainsCondComb(child.Condition, Instruction.LogicalOr, stmt.Condition))
{
child.OrCondition(stmt.Condition);
}
}
else if (child.Type == AstBlockType.Else)
{
// Modify the matching if condition to force the else to be entered by the goto.
if (!(Previous(child) is AstBlock ifBlock) || ifBlock.Type != AstBlockType.If)
{
throw new InvalidOperationException("Found an else without a matching if.");
}
IAstNode cond = InverseCond(stmt.Condition);
if (!ContainsCondComb(ifBlock.Condition, Instruction.LogicalAnd, cond))
{
ifBlock.AndCondition(cond);
}
last = ifBlock;
}
Enclose(block, AstBlockType.If, stmt.Condition, Next(stmt.Goto), last);
block.Remove(stmt.Goto);
child.AddFirst(stmt.Goto);
block = child;
}
}
private static AstBlock EncloseDoWhile(GotoStatement stmt, AstBlock block, IAstNode first)
{
if (block.Type == AstBlockType.DoWhile && first == block.First)
{
// We only need to insert the continue if we're not at the end of the loop,
// or if our condition is different from the loop condition.
if (Next(stmt.Goto) != null || block.Condition != stmt.Condition)
{
EncloseSingleInst(stmt, Instruction.LoopContinue);
}
// Modify the do-while condition to allow it to continue.
if (!ContainsCondComb(block.Condition, Instruction.LogicalOr, stmt.Condition))
{
block.OrCondition(stmt.Condition);
}
return(block);
}
return(Enclose(block, AstBlockType.DoWhile, stmt.Condition, first, stmt.Goto));
}