List <ILNode> FindConditions(HashSet <ControlFlowNode> scope, ControlFlowNode entryNode)
{
List <ILNode> result = new List <ILNode>();
// Do not modify entry data
scope = new HashSet <ControlFlowNode>(scope);
Stack <ControlFlowNode> agenda = new Stack <ControlFlowNode>();
agenda.Push(entryNode);
while (agenda.Count > 0)
{
ControlFlowNode node = agenda.Pop();
// Find a block that represents a simple condition
if (scope.Contains(node))
{
ILBasicBlock block = (ILBasicBlock)node.UserData;
{
IList <ILExpression> conditions;
ILLabel fallLabel;
// Switch
FakeSwitch fswitch;
if (block.MatchLastAndBr(GMCode.Switch, out fswitch, out conditions, out fallLabel))
{
ILSwitch ilSwitch = new ILSwitch()
{
Condition = fswitch.SwitchExpression
};
block.Body[block.Body.Count - 2] = ilSwitch; // replace it, nothing else needs to be done!
result.Add(block); // except add it to the result, DOLT
scope.RemoveOrThrow(node); // Remove the item so that it is not picked up as content
// Pull in code of cases
ControlFlowNode fallTarget = null;
labelToCfNode.TryGetValue(fallLabel, out fallTarget);
HashSet <ControlFlowNode> frontiers = new HashSet <ControlFlowNode>();
if (fallTarget != null)
{
frontiers.UnionWith(fallTarget.DominanceFrontier.Except(new[] { fallTarget }));
}
foreach (ILLabel condLabel in fswitch.CaseExpressions.Select(x => x.Value))
{
ControlFlowNode condTarget = null;
labelToCfNode.TryGetValue(condLabel, out condTarget);
if (condTarget != null)
{
frontiers.UnionWith(condTarget.DominanceFrontier.Except(new[] { condTarget }));
}
}
for (int i = 0; i < fswitch.CaseExpressions.Count; i++)
{
ILLabel condLabel = fswitch.CaseExpressions[i].Value;
// Find or create new case block
ILSwitch.ILCase caseBlock = ilSwitch.Cases.FirstOrDefault(b => b.EntryGoto.Operand == condLabel);
if (caseBlock == null)
{
caseBlock = new ILSwitch.ILCase()
{
Values = new List <ILExpression>(),
EntryGoto = new ILExpression(GMCode.B, condLabel)
};
ilSwitch.Cases.Add(caseBlock);
ControlFlowNode condTarget = null;
labelToCfNode.TryGetValue(condLabel, out condTarget);
if (condTarget != null && !frontiers.Contains(condTarget))
{
HashSet <ControlFlowNode> content = FindDominatedNodes(scope, condTarget);
scope.ExceptWith(content);
foreach (var con in FindConditions(content, condTarget))
{
caseBlock.Body.Add(con);
}
// caseBlock.Body.AddRange(FindConditions(content, condTarget));
// Add explicit break which should not be used by default, but the goto removal might decide to use it
caseBlock.Body.Add(new ILBasicBlock()
{
Body =
{
ILLabel.Generate("SwitchBreak", (int)nextLabelIndex++),
new ILExpression(GMCode.LoopOrSwitchBreak, null)
}
});
}
}
caseBlock.Values.Add(fswitch.CaseExpressions[i].Key);
}
// Heuristis to determine if we want to use fallthough as default case
if (fallTarget != null && !frontiers.Contains(fallTarget))
{
HashSet <ControlFlowNode> content = FindDominatedNodes(scope, fallTarget);
if (content.Any())
{
var caseBlock = new ILSwitch.ILCase()
{
EntryGoto = new ILExpression(GMCode.B, fallLabel)
};
ilSwitch.Cases.Add(caseBlock);
block.Body.RemoveTail(GMCode.B);
scope.ExceptWith(content);
foreach (var con in FindConditions(content, fallTarget))
{
caseBlock.Body.Add(con);
}
// Add explicit break which should not be used by default, but the goto removal might decide to use it
caseBlock.Body.Add(new ILBasicBlock()
{
Body =
{
ILLabel.Generate("SwitchBreak", (int)nextLabelIndex++),
new ILExpression(GMCode.LoopOrSwitchBreak, null)
}
});
}
}
}
// Debug.Assert((block.Body.First() as ILLabel).Name != "L1938");
// Two-way branch
ILLabel trueLabel;
ILLabel falseLabel;
IList <ILExpression> condExprs;
if (block.MatchLastAndBr(GMCode.Bt, out trueLabel, out condExprs, out falseLabel) && // be sure to invert this condition
condExprs.Count > 0) // its resolved
{
ILExpression condExpr = condExprs[0];
IList <ILNode> body = block.Body;
// this is a simple condition, skip anything short curiket for now
// Match a condition patern
// Convert the brtrue to ILCondition
ILCondition ilCond = new ILCondition()
{
Condition = condExpr, //code == GMCode.Bf ? condExpr : condExpr.NegateCondition(),
TrueBlock = new ILBlock()
{
EntryGoto = new ILExpression(GMCode.B, trueLabel)
},
FalseBlock = new ILBlock()
{
EntryGoto = new ILExpression(GMCode.B, falseLabel)
}
};
block.Body.RemoveTail(GMCode.Bt, GMCode.B);
block.Body.Add(ilCond);
result.Add(block);
// Remove the item immediately so that it is not picked up as content
scope.RemoveOrThrow(node);
ControlFlowNode trueTarget = null;
labelToCfNode.TryGetValue(trueLabel, out trueTarget);
ControlFlowNode falseTarget = null;
labelToCfNode.TryGetValue(falseLabel, out falseTarget);
// Pull in the conditional code
if (trueTarget != null && HasSingleEdgeEnteringBlock(trueTarget))
{
HashSet <ControlFlowNode> content = FindDominatedNodes(scope, trueTarget);
scope.ExceptWith(content);
foreach (var con in FindConditions(content, trueTarget))
{
ilCond.TrueBlock.Body.Add(con);
}
}
if (falseTarget != null && HasSingleEdgeEnteringBlock(falseTarget))
{
HashSet <ControlFlowNode> content = FindDominatedNodes(scope, falseTarget);
scope.ExceptWith(content);
foreach (var con in FindConditions(content, falseTarget))
{
ilCond.FalseBlock.Body.Add(con);
}
}
}
}
// Add the node now so that we have good ordering
if (scope.Contains(node))
{
result.Add((ILNode)node.UserData);
scope.Remove(node);
}
}
// depth-first traversal of dominator tree
for (int i = node.DominatorTreeChildren.Count - 1; i >= 0; i--)
{
agenda.Push(node.DominatorTreeChildren[i]);
}
}
// Add whatever is left
foreach (var node in scope)
{
result.Add((ILNode)node.UserData);
}
return(result);
}
List<ILNode> FindConditions(HashSet<ControlFlowNode> scope, ControlFlowNode entryNode)
{
List<ILNode> result = new List<ILNode>();
// Do not modify entry data
scope = new HashSet<ControlFlowNode>(scope);
Stack<ControlFlowNode> agenda = new Stack<ControlFlowNode>();
agenda.Push(entryNode);
while (agenda.Count > 0)
{
ControlFlowNode node = agenda.Pop();
// Find a block that represents a simple condition
if (scope.Contains(node))
{
ILBasicBlock block = (ILBasicBlock)node.UserData;
{
IList<ILExpression> conditions;
ILLabel fallLabel;
// Switch
FakeSwitch fswitch;
if (block.MatchLastAndBr(GMCode.Switch, out fswitch, out conditions, out fallLabel))
{
ILSwitch ilSwitch = new ILSwitch() { Condition = fswitch.SwitchExpression };
block.Body[block.Body.Count - 2] = ilSwitch; // replace it, nothing else needs to be done!
result.Add(block); // except add it to the result, DOLT
scope.RemoveOrThrow(node);// Remove the item so that it is not picked up as content
// Pull in code of cases
ControlFlowNode fallTarget = null;
labelToCfNode.TryGetValue(fallLabel, out fallTarget);
HashSet<ControlFlowNode> frontiers = new HashSet<ControlFlowNode>();
if (fallTarget != null)
frontiers.UnionWith(fallTarget.DominanceFrontier.Except(new[] { fallTarget }));
foreach (ILLabel condLabel in fswitch.CaseExpressions.Select(x => x.Value))
{
ControlFlowNode condTarget = null;
labelToCfNode.TryGetValue(condLabel, out condTarget);
if (condTarget != null)
frontiers.UnionWith(condTarget.DominanceFrontier.Except(new[] { condTarget }));
}
for (int i = 0; i < fswitch.CaseExpressions.Count; i++)
{
ILLabel condLabel = fswitch.CaseExpressions[i].Value;
// Find or create new case block
ILSwitch.ILCase caseBlock = ilSwitch.Cases.FirstOrDefault(b => b.EntryGoto.Operand == condLabel);
if (caseBlock == null)
{
caseBlock = new ILSwitch.ILCase()
{
Values = new List<ILExpression>(),
EntryGoto = new ILExpression(GMCode.B, condLabel)
};
ilSwitch.Cases.Add(caseBlock);
ControlFlowNode condTarget = null;
labelToCfNode.TryGetValue(condLabel, out condTarget);
if (condTarget != null && !frontiers.Contains(condTarget))
{
HashSet<ControlFlowNode> content = FindDominatedNodes(scope, condTarget);
scope.ExceptWith(content);
foreach (var con in FindConditions(content, condTarget)) caseBlock.Body.Add(con);
// caseBlock.Body.AddRange(FindConditions(content, condTarget));
// Add explicit break which should not be used by default, but the goto removal might decide to use it
caseBlock.Body.Add(new ILBasicBlock()
{
Body = {
ILLabel.Generate("SwitchBreak" ,(int)nextLabelIndex++),
new ILExpression(GMCode.LoopOrSwitchBreak, null)
}
});
}
}
caseBlock.Values.Add(fswitch.CaseExpressions[i].Key);
}
// Heuristis to determine if we want to use fallthough as default case
if (fallTarget != null && !frontiers.Contains(fallTarget))
{
HashSet<ControlFlowNode> content = FindDominatedNodes(scope, fallTarget);
if (content.Any())
{
var caseBlock = new ILSwitch.ILCase() { EntryGoto = new ILExpression(GMCode.B, fallLabel) };
ilSwitch.Cases.Add(caseBlock);
block.Body.RemoveTail(GMCode.B);
scope.ExceptWith(content);
foreach (var con in FindConditions(content, fallTarget)) caseBlock.Body.Add(con);
// Add explicit break which should not be used by default, but the goto removal might decide to use it
caseBlock.Body.Add(new ILBasicBlock()
{
Body = {
ILLabel.Generate("SwitchBreak" ,(int)nextLabelIndex++),
new ILExpression(GMCode.LoopOrSwitchBreak, null)
}
});
}
}
}
// Debug.Assert((block.Body.First() as ILLabel).Name != "L1938");
// Two-way branch
ILLabel trueLabel;
ILLabel falseLabel;
IList<ILExpression> condExprs;
if (block.MatchLastAndBr(GMCode.Bt, out trueLabel, out condExprs, out falseLabel) // be sure to invert this condition
&& condExprs.Count > 0) // its resolved
{
ILExpression condExpr = condExprs[0];
IList<ILNode> body = block.Body;
// this is a simple condition, skip anything short curiket for now
// Match a condition patern
// Convert the brtrue to ILCondition
ILCondition ilCond = new ILCondition()
{
Condition = condExpr, //code == GMCode.Bf ? condExpr : condExpr.NegateCondition(),
TrueBlock = new ILBlock() { EntryGoto = new ILExpression(GMCode.B, trueLabel) },
FalseBlock = new ILBlock() { EntryGoto = new ILExpression(GMCode.B, falseLabel) }
};
block.Body.RemoveTail(GMCode.Bt, GMCode.B);
block.Body.Add(ilCond);
result.Add(block);
// Remove the item immediately so that it is not picked up as content
scope.RemoveOrThrow(node);
ControlFlowNode trueTarget = null;
labelToCfNode.TryGetValue(trueLabel, out trueTarget);
ControlFlowNode falseTarget = null;
labelToCfNode.TryGetValue(falseLabel, out falseTarget);
// Pull in the conditional code
if (trueTarget != null && HasSingleEdgeEnteringBlock(trueTarget))
{
HashSet<ControlFlowNode> content = FindDominatedNodes(scope, trueTarget);
scope.ExceptWith(content);
foreach (var con in FindConditions(content, trueTarget)) ilCond.TrueBlock.Body.Add(con);
}
if (falseTarget != null && HasSingleEdgeEnteringBlock(falseTarget))
{
HashSet<ControlFlowNode> content = FindDominatedNodes(scope, falseTarget);
scope.ExceptWith(content);
foreach (var con in FindConditions(content, falseTarget)) ilCond.FalseBlock.Body.Add(con);
}
}
}
// Add the node now so that we have good ordering
if (scope.Contains(node))
{
result.Add((ILNode)node.UserData);
scope.Remove(node);
}
}
// depth-first traversal of dominator tree
for (int i = node.DominatorTreeChildren.Count - 1; i >= 0; i--)
{
agenda.Push(node.DominatorTreeChildren[i]);
}
}
// Add whatever is left
foreach (var node in scope)
{
result.Add((ILNode)node.UserData);
}
return result;
}
