public void CopiesWhereIntermediateIsOverwritten()
{
var source = @"
var x = 1;
var y = x;
y = 2;
var z = y;";
var cfg = CreateControlFlowGraph(source);
var analysis = CopyPropagationAnalysis.Analyze(cfg);
var assignmentX = _GetNodeWithSyntax(cfg, "Assignment: x = 1");
var assignmentY1 = _GetNodeWithSyntax(cfg, "Assignment: y = x");
var assignmentY2 = _GetNodeWithSyntax(cfg, "Assignment: y = 2");
var assignmentZ = _GetNodeWithSyntax(cfg, "Assignment: z = y");
Assert.AreEqual(0, analysis.Entry[assignmentX].Count);
Assert.AreEqual(0, analysis.Exit[assignmentX].Count);
Assert.AreEqual(0, analysis.Entry[assignmentY1].Count);
Assert.AreEqual(1, analysis.Exit[assignmentY1].Count);
Assert.AreEqual(new VariableCopy(assignmentY1, "y", "x"), analysis.Exit[assignmentY1].Single());
Assert.AreEqual(1, analysis.Entry[assignmentY2].Count);
Assert.IsTrue(analysis.Entry[assignmentY2].SetEquals(analysis.Exit[assignmentY1]));
Assert.AreEqual(0, analysis.Exit[assignmentY2].Count);
Assert.AreEqual(0, analysis.Entry[assignmentZ].Count);
Assert.AreEqual(1, analysis.Exit[assignmentZ].Count);
Assert.AreEqual(new VariableCopy(assignmentZ, "z", "y"), analysis.Exit[assignmentZ].Single());
}
private CopyPropagation(Code input, ControlFlowGraph cfg, CopyPropagationAnalysis analysis,
IDictionary <Instruction, FlowNode> instructionNodeMapping)
{
_input = input;
_cfg = cfg;
_analysis = analysis;
_instructionNodeMapping = instructionNodeMapping;
}
/// <summary>
/// Optimizes the given IR code by applying a copy propagation.
/// </summary>
/// <param name="code">The code to optimize.</param>
/// <param name="controlFlowGraph">The control flow graph of the code.</param>
/// <returns>A tuple of the possibly optimized code and a flag identifying if a change was applied.</returns>
public static (Code Code, bool Changed) Optimize(Code code, ControlFlowGraph controlFlowGraph)
{
var analysis = CopyPropagationAnalysis.Analyze(controlFlowGraph);
var mapping = controlFlowGraph.Nodes
.ToDictionary(node => node.Instruction, node => node)
.ToImmutableDictionary();
var instance = new CopyPropagation(code, controlFlowGraph, analysis, mapping);
return(instance._Optimize(), instance._changed);
}
public void DirectCopy()
{
var source = @"var a = 1; var b = a;";
var cfg = CreateControlFlowGraph(source);
var analysis = CopyPropagationAnalysis.Analyze(cfg);
var assignmentA = _GetNodeWithSyntax(cfg, "Assignment: a = 1");
var assignmentB = _GetNodeWithSyntax(cfg, "Assignment: b = a");
Assert.AreEqual(0, analysis.Entry[assignmentA].Count);
Assert.AreEqual(0, analysis.Exit[assignmentA].Count);
Assert.AreEqual(0, analysis.Entry[assignmentB].Count);
Assert.AreEqual(1, analysis.Exit[assignmentB].Count);
Assert.AreEqual(new VariableCopy(assignmentB, "b", "a"), analysis.Exit[assignmentB].Single());
}
public void NestedCopiesOnlyCopyIntermediate()
{
var source = @"
var x = 1;
var y = x;
var z = y;
var a = z;";
var cfg = CreateControlFlowGraph(source);
var analysis = CopyPropagationAnalysis.Analyze(cfg);
var assignmentX = _GetNodeWithSyntax(cfg, "Assignment: x = 1");
var assignmentY = _GetNodeWithSyntax(cfg, "Assignment: y = x");
var assignmentZ = _GetNodeWithSyntax(cfg, "Assignment: z = y");
var assignmentA = _GetNodeWithSyntax(cfg, "Assignment: a = z");
Assert.AreEqual(0, analysis.Entry[assignmentX].Count);
Assert.AreEqual(0, analysis.Exit[assignmentX].Count);
Assert.AreEqual(0, analysis.Entry[assignmentY].Count);
Assert.AreEqual(1, analysis.Exit[assignmentY].Count);
Assert.AreEqual(new VariableCopy(assignmentY, "y", "x"), analysis.Exit[assignmentY].Single());
Assert.AreEqual(1, analysis.Entry[assignmentZ].Count);
Assert.IsTrue(analysis.Entry[assignmentZ].SetEquals(analysis.Exit[assignmentY]));
Assert.AreEqual(2, analysis.Exit[assignmentZ].Count);
var expectedAfterZ = new HashSet <VariableCopy> {
new VariableCopy(assignmentY, "y", "x"),
new VariableCopy(assignmentZ, "z", "y"),
};
Assert.IsTrue(expectedAfterZ.SetEquals(analysis.Exit[assignmentZ]));
Assert.AreEqual(2, analysis.Entry[assignmentA].Count);
Assert.IsTrue(analysis.Entry[assignmentA].SetEquals(analysis.Exit[assignmentZ]));
Assert.AreEqual(3, analysis.Exit[assignmentA].Count);
var expectedAfterA = new HashSet <VariableCopy> {
new VariableCopy(assignmentY, "y", "x"),
new VariableCopy(assignmentZ, "z", "y"),
new VariableCopy(assignmentA, "a", "z"),
};
Assert.IsTrue(expectedAfterA.SetEquals(analysis.Exit[assignmentA]));
}
public void CopyAfterLoopBranch()
{
var source = @"
var x = 1;
for(var i = 0; i < 10; ++i) {
x = 2;
}
var y = x;";
var cfg = CreateControlFlowGraph(source);
var analysis = CopyPropagationAnalysis.Analyze(cfg);
var assignmentX1 = _GetNodeWithSyntax(cfg, "Assignment: x = 1");
var assignmentX2 = _GetNodeWithSyntax(cfg, "Assignment: x = 2");
var assignmentY = _GetNodeWithSyntax(cfg, "Assignment: y = x");
Assert.AreEqual(0, analysis.Entry[assignmentX1].Count);
Assert.AreEqual(0, analysis.Exit[assignmentX1].Count);
Assert.AreEqual(0, analysis.Entry[assignmentX2].Count);
Assert.AreEqual(0, analysis.Exit[assignmentX2].Count);
Assert.AreEqual(0, analysis.Entry[assignmentY].Count);
Assert.AreEqual(1, analysis.Exit[assignmentY].Count);
Assert.AreEqual(new VariableCopy(assignmentY, "y", "x"), analysis.Exit[assignmentY].Single());
}
public InstructionVisitor(CopyPropagationAnalysis analysis, FlowNode flowNode)
{
_analysis = analysis;
_flowNode = flowNode;
}
