protected override BoundStatement RewriteWhileStatement(BoundWhileStatement node)
{
// while <condition>
// <body>
//
// ----->
//
// goto continue
// body:
// <body>
// continue:
// gotoTrue <condition> body
// break:
var bodyLabel = GenerateLabel();
var result = BoundNodeFactory.Block(node.Syntax,
BoundNodeFactory.Goto(node.Syntax, node.ContinueLabel),
BoundNodeFactory.Label(node.Syntax, bodyLabel),
node.Body,
BoundNodeFactory.Label(node.Syntax, node.ContinueLabel),
BoundNodeFactory.GotoTrue(node.Syntax, bodyLabel, node.Condition),
BoundNodeFactory.Label(node.Syntax, node.BreakLabel)
);
return(RewriteStatement(result));
}
protected override BoundStatement RewriteIfStatement(BoundIfStatement node)
{
if (node.ElseStatement == null)
{
// if <condition>
// <then>
//
// ---->
//
// gotoFalse <condition> end
// <then>
// end:
var endLabel = GenerateLabel();
var result = BoundNodeFactory.Block(node.Syntax,
BoundNodeFactory.GotoFalse(node.Syntax, endLabel, node.Condition),
node.ThenStatement,
BoundNodeFactory.Label(node.Syntax, endLabel)
);
return(RewriteStatement(result));
}
else
{
// if <condition>
// <then>
// else
// <else>
//
// ---->
//
// gotoFalse <condition> else
// <then>
// goto end
// else:
// <else>
// end:
var elseLabel = GenerateLabel();
var endLabel = GenerateLabel();
var result = BoundNodeFactory.Block(node.Syntax,
BoundNodeFactory.GotoFalse(node.Syntax, elseLabel, node.Condition),
node.ThenStatement,
BoundNodeFactory.Goto(node.Syntax, endLabel),
BoundNodeFactory.Label(node.Syntax, elseLabel),
node.ElseStatement,
BoundNodeFactory.Label(node.Syntax, endLabel)
);
return(RewriteStatement(result));
}
}
protected override BoundStatement RewriteConditionalGotoStatement(BoundConditionalGotoStatement node)
{
if (node.Condition.ConstantValue != null)
{
var condition = (bool)node.Condition.ConstantValue.Value !;
condition = node.JumpIfTrue ? condition : !condition;
if (condition)
{
return(RewriteStatement(BoundNodeFactory.Goto(node.Syntax, node.Label)));
}
else
{
return(RewriteStatement(BoundNodeFactory.Nop(node.Syntax)));
}
}
return(base.RewriteConditionalGotoStatement(node));
}