private CommonSubexpressionElimination(Code input, ControlFlowGraph cfg, AvailableExpressionsAnalysis analysis,
IDictionary <Instruction, FlowNode> instructionNodeMapping)
{
_input = input;
_cfg = cfg;
_analysis = analysis;
_instructionNodeMapping = instructionNodeMapping;
}
public static (Code Code, bool Changed) Optimize(Code code, ControlFlowGraph controlFlowGraph)
{
var analysis = AvailableExpressionsAnalysis.Analyze(controlFlowGraph);
var mapping = controlFlowGraph.Nodes
.ToDictionary(node => node.Instruction, node => node)
.ToImmutableDictionary();
var instance = new CommonSubexpressionElimination(code, controlFlowGraph, analysis, mapping);
return(instance._Optimize(), instance._changed);
}
public void ConstantAssignmentYieldsNoAvailableExpression()
{
var source = @"x = 1;";
var cfg = CreateControlFlowGraph(source);
var analysis = AvailableExpressionsAnalysis.Analyze(cfg);
var originalAssignment = _GetNodeWithSyntax(cfg, "Assignment: x = 1");
Assert.AreEqual(0, analysis.Entry[originalAssignment].Count);
Assert.AreEqual(0, analysis.Exit[originalAssignment].Count);
}
public void SelfAssignmentWithMethodInvocationIsNotAvailable()
{
var source = @"x = Method(x);";
var cfg = CreateControlFlowGraph(source);
var analysis = AvailableExpressionsAnalysis.Analyze(cfg);
var assignment = _GetNodeWithSyntax(cfg, "Assignment: x = Method(x)");
Assert.AreEqual(0, analysis.Entry[assignment].Count);
Assert.AreEqual(0, analysis.Exit[assignment].Count);
}
public void InvocationAssignmentYieldsAvailableExpression()
{
var source = @"x = Method(1);";
var cfg = CreateControlFlowGraph(source);
var analysis = AvailableExpressionsAnalysis.Analyze(cfg);
var originalAssignment = _GetNodeWithSyntax(cfg, "Assignment: x = Method(1)");
Assert.AreEqual(0, analysis.Entry[originalAssignment].Count);
Assert.AreEqual(1, analysis.Exit[originalAssignment].Count);
Assert.AreEqual(new AvailableExpression(originalAssignment, new InvocationExpression("Method", new[] { new IntegerExpression(1) })), analysis.Exit[originalAssignment].Single());
}
public void BinaryAssignmentYieldsAvailableExpression()
{
var source = @"x = 1 * 2;";
var cfg = CreateControlFlowGraph(source);
var analysis = AvailableExpressionsAnalysis.Analyze(cfg);
var originalAssignment = _GetNodeWithSyntax(cfg, "Assignment: x = 1 * 2");
Assert.AreEqual(0, analysis.Entry[originalAssignment].Count);
Assert.AreEqual(1, analysis.Exit[originalAssignment].Count);
Assert.AreEqual(new AvailableExpression(originalAssignment, new MultiplyExpression(new IntegerExpression(1), new IntegerExpression(2))), analysis.Exit[originalAssignment].Single());
}
public void BookExample()
{
var source = @"
x = a + b;
y = a * b;
while(y > a + b) {
a = a + 1;
x = a + b;
}";
var cfg = CreateControlFlowGraph(source);
var analysis = AvailableExpressionsAnalysis.Analyze(cfg);
var instruction1 = _GetNodeWithSyntax(cfg, "Assignment: x = a + b");
Assert.AreEqual(0, analysis.Entry[instruction1].Count);
Assert.AreEqual(1, analysis.Exit[instruction1].Count);
Assert.AreEqual(new AvailableExpression(instruction1, new AddExpression(new VariableExpression("a"), new VariableExpression("b"))), analysis.Exit[instruction1].Single());
var instruction2 = _GetNodeWithSyntax(cfg, "Assignment: y = a * b");
Assert.AreEqual(1, analysis.Entry[instruction2].Count);
Assert.IsTrue(analysis.Exit[instruction1].SetEquals(analysis.Entry[instruction2]));
Assert.AreEqual(2, analysis.Exit[instruction2].Count);
var expected2 = new HashSet <AvailableExpression> {
new AvailableExpression(instruction1, new AddExpression(new VariableExpression("a"), new VariableExpression("b"))),
new AvailableExpression(instruction2, new MultiplyExpression(new VariableExpression("a"), new VariableExpression("b")))
};
Assert.IsTrue(analysis.Exit[instruction2].SetEquals(expected2));
var tInstruction3 = _GetNodeWithSyntax(cfg, "Assignment: $temp_0 = a + b");
var cInstruction3 = _GetNodeWithSyntax(cfg, "ConditionalJump: y > $temp_0");
Assert.AreEqual(1, analysis.Entry[cInstruction3].Count);
Assert.IsFalse(analysis.Exit[instruction2].SetEquals(analysis.Entry[cInstruction3]));
Assert.AreEqual(1, analysis.Exit[cInstruction3].Count);
Assert.AreEqual(new AvailableExpression(tInstruction3, new AddExpression(new VariableExpression("a"), new VariableExpression("b"))), analysis.Exit[cInstruction3].Single());
var instruction4 = _GetNodeWithSyntax(cfg, "Assignment: a = a + 1");
Assert.AreEqual(1, analysis.Entry[instruction4].Count);
Assert.IsTrue(analysis.Exit[cInstruction3].SetEquals(analysis.Entry[instruction4]));
Assert.AreEqual(0, analysis.Exit[instruction4].Count);
var instruction5 = _GetNodeWithSyntax(cfg, "Assignment: x = a + b");
Assert.AreEqual(0, analysis.Entry[instruction5].Count);
Assert.IsTrue(analysis.Exit[instruction4].SetEquals(analysis.Entry[instruction5]));
Assert.AreEqual(1, analysis.Exit[instruction5].Count);
Assert.AreEqual(new AvailableExpression(instruction1, new AddExpression(new VariableExpression("a"), new VariableExpression("b"))), analysis.Exit[instruction5].Single());
}
public void MultipleInvocationExpressionsWithKilling()
{
var source = @"y = Method(x); x = Method(1);";
var cfg = CreateControlFlowGraph(source);
var analysis = AvailableExpressionsAnalysis.Analyze(cfg);
var assignment1 = _GetNodeWithSyntax(cfg, "Assignment: y = Method(x)");
Assert.AreEqual(0, analysis.Entry[assignment1].Count);
Assert.AreEqual(1, analysis.Exit[assignment1].Count);
Assert.AreEqual(new AvailableExpression(assignment1, new InvocationExpression("Method", new[] { new VariableExpression("x") })), analysis.Exit[assignment1].Single());
var assignment2 = _GetNodeWithSyntax(cfg, "Assignment: x = Method(1)");
Assert.AreEqual(1, analysis.Entry[assignment2].Count);
Assert.AreEqual(1, analysis.Exit[assignment2].Count);
var expected = new HashSet <AvailableExpression> {
new AvailableExpression(assignment2, new InvocationExpression("Method", new [] { new IntegerExpression(1) }))
};
Assert.IsTrue(analysis.Exit[assignment2].SetEquals(expected));
}
public void MultipleBinaryExpressionsWithKilling()
{
var source = @"y = x * 2; x = 4 + 10;";
var cfg = CreateControlFlowGraph(source);
var analysis = AvailableExpressionsAnalysis.Analyze(cfg);
var assignment1 = _GetNodeWithSyntax(cfg, "Assignment: y = x * 2");
Assert.AreEqual(0, analysis.Entry[assignment1].Count);
Assert.AreEqual(1, analysis.Exit[assignment1].Count);
Assert.AreEqual(new AvailableExpression(assignment1, new MultiplyExpression(new VariableExpression("x"), new IntegerExpression(2))), analysis.Exit[assignment1].Single());
var assignment2 = _GetNodeWithSyntax(cfg, "Assignment: x = 4 + 10");
Assert.AreEqual(1, analysis.Entry[assignment2].Count);
Assert.AreEqual(1, analysis.Exit[assignment2].Count);
var expected = new HashSet <AvailableExpression> {
new AvailableExpression(assignment2, new AddExpression(new IntegerExpression(4), new IntegerExpression(10)))
};
Assert.IsTrue(analysis.Exit[assignment2].SetEquals(expected));
}
