public static void OptimizeIf(Branch condition)
{
Node trueStart = condition.FloatUpToNeighbours(condition.TrueSuccessor);
Node falseStart = condition.FloatUpToNeighbours(condition.FalseSuccessor);
NodeCollection trueReachable = trueStart != null ? trueStart.GetReachableNodes() : NodeCollection.Empty;
NodeCollection falseReachable = falseStart != null ? falseStart.GetReachableNodes() : NodeCollection.Empty;
NodeCollection commonReachable = NodeCollection.Intersect(trueReachable, falseReachable);
NodeCollection trueNodes = trueReachable.Clone();
trueNodes.RemoveRange(commonReachable);
NodeCollection falseNodes = falseReachable.Clone();
falseNodes.RemoveRange(commonReachable);
// Replace the basic block with condition node
Node conditionParent = condition.Parent;
int conditionIndex = condition.Index;
ConditionalNode conditionalNode = new ConditionalNode(condition);
conditionalNode.MoveTo(conditionParent, conditionIndex);
// If there are no common nodes, let the 'true' block be the default
if (commonReachable.Count > 0) {
trueNodes.MoveTo(conditionalNode.TrueBody);
}
falseNodes.MoveTo(conditionalNode.FalseBody);
// Optimize the created subtrees
conditionalNode.TrueBody.OptimizeConditions();
conditionalNode.FalseBody.OptimizeConditions();
}
Ast.Expression MakeBranchCondition_Internal(Branch branch)
{
if (branch is SimpleBranch) {
List<Ast.Expression> args = TransformExpressionArguments((ILExpression)((SimpleBranch)branch).BasicBlock.Body[0]);
Ast.Expression arg1 = args.Count >= 1 ? args[0] : null;
Ast.Expression arg2 = args.Count >= 2 ? args[1] : null;
switch(((ILExpression)((SimpleBranch)branch).BasicBlock.Body[0]).OpCode.Code) {
case Code.Brfalse: return new Ast.UnaryOperatorExpression(arg1, UnaryOperatorType.Not);
case Code.Brtrue: return arg1;
case Code.Beq: return new Ast.BinaryOperatorExpression(arg1, BinaryOperatorType.Equality, arg2);
case Code.Bge: return new Ast.BinaryOperatorExpression(arg1, BinaryOperatorType.GreaterThanOrEqual, arg2);
case Code.Bge_Un: return new Ast.BinaryOperatorExpression(arg1, BinaryOperatorType.GreaterThanOrEqual, arg2);
case Code.Bgt: return new Ast.BinaryOperatorExpression(arg1, BinaryOperatorType.GreaterThan, arg2);
case Code.Bgt_Un: return new Ast.BinaryOperatorExpression(arg1, BinaryOperatorType.GreaterThan, arg2);
case Code.Ble: return new Ast.BinaryOperatorExpression(arg1, BinaryOperatorType.LessThanOrEqual, arg2);
case Code.Ble_Un: return new Ast.BinaryOperatorExpression(arg1, BinaryOperatorType.LessThanOrEqual, arg2);
case Code.Blt: return new Ast.BinaryOperatorExpression(arg1, BinaryOperatorType.LessThan, arg2);
case Code.Blt_Un: return new Ast.BinaryOperatorExpression(arg1, BinaryOperatorType.LessThan, arg2);
case Code.Bne_Un: return new Ast.BinaryOperatorExpression(arg1, BinaryOperatorType.InEquality, arg2);
case Code.Leave: return new Ast.PrimitiveExpression(true, true.ToString());
default: throw new Exception("Bad opcode");
}
} else if (branch is ShortCircuitBranch) {
ShortCircuitBranch scBranch = (ShortCircuitBranch)branch;
switch(scBranch.Operator) {
case ShortCircuitOperator.LeftAndRight:
return new BinaryOperatorExpression(
MakeBranchCondition(scBranch.Left),
BinaryOperatorType.LogicalAnd,
MakeBranchCondition(scBranch.Right)
);
case ShortCircuitOperator.LeftOrRight:
return new BinaryOperatorExpression(
MakeBranchCondition(scBranch.Left),
BinaryOperatorType.LogicalOr,
MakeBranchCondition(scBranch.Right)
);
case ShortCircuitOperator.NotLeftAndRight:
return new BinaryOperatorExpression(
new UnaryOperatorExpression(MakeBranchCondition(scBranch.Left), UnaryOperatorType.Not),
BinaryOperatorType.LogicalAnd,
MakeBranchCondition(scBranch.Right)
);
case ShortCircuitOperator.NotLeftOrRight:
return new BinaryOperatorExpression(
new UnaryOperatorExpression(MakeBranchCondition(scBranch.Left), UnaryOperatorType.Not),
BinaryOperatorType.LogicalOr,
MakeBranchCondition(scBranch.Right)
);
default:
throw new Exception("Bad operator");
}
} else {
throw new Exception("Bad type");
}
}
Ast.Expression MakeBranchCondition(Branch branch)
{
return new ParenthesizedExpression(MakeBranchCondition_Internal(branch));
}
public ConditionalNode(Branch condition)
{
this.condition = condition;
condition.MoveTo(this);
trueBody.MoveTo(this);
falseBody.MoveTo(this);
}