public BBLoop(BasicBlock head, BasicBlock tail, IMSet <BasicBlock> body, JST.Identifier label)
{
Head = head;
Tail = tail;
Body = body;
Label = label;
var headEscapes = false;
var headbranchbb = head as BranchBasicBlock;
foreach (var t in head.Targets)
{
if (!body.Contains(t))
{
headEscapes = true;
}
}
var tailEscapes = false;
var tailbranchbb = tail as BranchBasicBlock;
foreach (var t in tail.Targets)
{
if (!body.Contains(t))
{
tailEscapes = true;
}
}
if (!headEscapes && tailEscapes && tailbranchbb != null)
{
if (tailbranchbb.Target.Equals(head))
{
Flavor = LoopFlavor.DoWhile;
}
else if (tailbranchbb.Fallthrough.Equals(head))
{
Flavor = LoopFlavor.FlippedDoWhile;
}
else
{
throw new InvalidOperationException("invalid loop");
}
}
else if (headEscapes && !tailEscapes && headbranchbb != null)
{
if (body.Contains(headbranchbb.Target))
{
Flavor = LoopFlavor.WhileDo;
}
else if (body.Contains(headbranchbb.Fallthrough))
{
Flavor = LoopFlavor.FlippedWhileDo;
}
else
{
throw new InvalidOperationException("invalid loop");
}
}
else if (!headEscapes && !tailEscapes)
{
Flavor = LoopFlavor.Loop;
}
else if (headEscapes && tailEscapes && headbranchbb != null && tailbranchbb != null)
{
// Could encode as do-while with a break at start, or while-do with a break at end.
if (body.Contains(headbranchbb.Target))
{
Flavor = LoopFlavor.WhileDo;
}
else if (body.Contains(headbranchbb.Fallthrough))
{
Flavor = LoopFlavor.FlippedWhileDo;
}
else
{
throw new InvalidOperationException("invalid loop");
}
}
else
{
Flavor = LoopFlavor.Unknown;
}
}