public ControlFlowGraph CreateControlFlowGraph(string body)
{
var code = TestCodeFactory.CreateThreeAddressCode(body);
Debug.WriteLine(CodeStringifier.Generate(code));
return(ControlFlowGraphFactory.Create(code));
}
/// <summary>
/// Optimizes the given three-address code and returns additional information.
/// </summary>
/// <param name="code">The code to optimize.</param>
/// <returns>A tuple containing the optimized code and a flag identifying if the code received any changes.</returns>
public static (Code Code, bool Changed) Optimize(Code code)
{
var changed = true;
var iterations = 0;
for (iterations = 0; iterations < MaxOptimizationIterations && changed; ++iterations)
{
changed = false;
foreach (var optimization in _optimizations)
{
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = optimization.Procedure(code, cfg);
if (optimized.Changed)
{
code = optimized.Code;
changed = true;
Debug.WriteLine($"the three-address code has been optimized by applying the {optimization.Label}");
}
}
}
Debug.WriteLine($"applied {iterations} optimization iterations; change in last iteration: {changed}");
return(code, changed || iterations > 1);
}
public void CodeWithSameVariableAndDoubleIntermediateOverwritingDoesNotAffectSucceedingCopies()
{
var source = @"
var x = 0;
var y = x;
var z = y;
x = 5;
var a = y;
var b = z;";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CopyPropagation.Optimize(code, cfg);
Assert.AreNotEqual(code, optimized.Code);
Assert.IsTrue(optimized.Changed);
var expected = @"
DECL x
x = 0
DECL y
y = x
DECL z
z = x
x = 5
DECL a
a = y
DECL b
b = y";
Assert.AreEqual(expected.Trim(), CodeStringifier.Generate(optimized.Code));
}
public void CodeWithUsageAndCopyInBranch()
{
var source = @"
var x = 0;
var y = 5;
if(x > 0) {
y = x;
var z = y;
}";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CopyPropagation.Optimize(code, cfg);
Assert.AreNotEqual(code, optimized.Code);
Assert.IsTrue(optimized.Changed);
var expected = @"
DECL x
x = 0
DECL y
y = 5
IF x > 0 JUMP #0
JUMP #1
LABEL #0
y = x
DECL z
z = x
LABEL #1";
Assert.AreEqual(expected.Trim(), CodeStringifier.Generate(optimized.Code));
}
public void CopyUsageInCondition()
{
var source = @"
var x = 0;
var y = x;
if(y == x) { }";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CopyPropagation.Optimize(code, cfg);
Assert.AreNotEqual(code, optimized.Code);
Assert.IsTrue(optimized.Changed);
var expected = @"
DECL x
x = 0
DECL y
y = x
IF x == x JUMP #0
JUMP #1
LABEL #0
LABEL #1";
Assert.AreEqual(expected.Trim(), CodeStringifier.Generate(optimized.Code));
}
public void CopyUsageInArrayAccessor()
{
var source = @"
var x = 0;
var y = x;
var z = 5 + array[y]";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CopyPropagation.Optimize(code, cfg);
Assert.AreNotEqual(code, optimized.Code);
Assert.IsTrue(optimized.Changed);
var expected = @"
DECL x
x = 0
DECL y
y = x
DECL z
DECL $temp_0
$temp_0 = array[x]
z = 5 + $temp_0";
Assert.AreEqual(expected.Trim(), CodeStringifier.Generate(optimized.Code));
}
public void CopyUsageInNestedMethodInvocations()
{
var source = @"
var x = 0;
var y = x;
Outer(x, Inner1(Inner2(y)));";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CopyPropagation.Optimize(code, cfg);
Assert.AreNotEqual(code, optimized.Code);
Assert.IsTrue(optimized.Changed);
var expected = @"
DECL x
x = 0
DECL y
y = x
DECL $temp_0
$temp_0 = Inner2(x)
DECL $temp_1
$temp_1 = Inner1($temp_0)
INVOKE Outer(x, $temp_1)";
Assert.AreEqual(expected.Trim(), CodeStringifier.Generate(optimized.Code));
}
public void CopyUsageInNestedBinaryExpressions()
{
var source = @"
var x = 0;
var y = x;
var a = 4;
var b = a;
var c = x + y * b - y;";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CopyPropagation.Optimize(code, cfg);
Assert.AreNotEqual(code, optimized.Code);
Assert.IsTrue(optimized.Changed);
var expected = @"
DECL x
x = 0
DECL y
y = x
DECL a
a = 4
DECL b
b = a
DECL c
DECL $temp_0
$temp_0 = x * a
DECL $temp_1
$temp_1 = x + $temp_0
c = $temp_1 - x";
Assert.AreEqual(expected.Trim(), CodeStringifier.Generate(optimized.Code));
}
public void CodeWithCodeWithCopyUsageDoesNotPropagateNestedCopies()
{
var source = @"
var x = 0;
var y = x;
var z = y;
var a = z;
var b = a;
var c = b;";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CopyPropagation.Optimize(code, cfg);
Assert.AreNotEqual(code, optimized.Code);
Assert.IsTrue(optimized.Changed);
var expected = @"
DECL x
x = 0
DECL y
y = x
DECL z
z = x
DECL a
a = y
DECL b
b = z
DECL c
c = a";
Assert.AreEqual(expected.Trim(), CodeStringifier.Generate(optimized.Code));
}
public void BodyWithSingleInvocation()
{
var invokerSource = @"var a = 10; Method(a);";
var invokerCfg = CreateControlFlowGraph(invokerSource);
var methodSource = @"
class Test {
private void Method(int x) {
}
}";
var semanticModel = DocumentFactory.Create().CreateSemanticModel(methodSource);
var methodCode = semanticModel.SyntaxTree.GetRoot().DescendantNodes()
.OfType <MethodDeclarationSyntax>()
.Select(declaration => CodeFactory.CreateMethod(declaration, semanticModel))
.Single();
var methodCfg = ControlFlowGraphFactory.Create(methodCode, "Method", true);
var procedureCfgs = new Dictionary <string, ControlFlowGraph> {
{ "Method", methodCfg }
};
var callGraph = CallGraphFactory.Create(invokerCfg, procedureCfgs);
Assert.AreEqual(4, callGraph.Edges.Count);
Assert.IsTrue(callGraph.Edges.Any(edge => edge.From is FlowInvocation && _IsExpectedTransfer(edge.To, "<root>", "Method", true, false)));
Assert.IsTrue(callGraph.Edges.Any(edge => _IsExpectedTransfer(edge.From, "<root>", "Method", true, false) && _IsExpectedBoundary(edge.To, "Method", FlowKind.Start)));
Assert.IsTrue(callGraph.Edges.Any(edge => _IsExpectedBoundary(edge.From, "Method", FlowKind.End) && _IsExpectedTransfer(edge.To, "Method", "<root>", false, true)));
Assert.IsTrue(callGraph.Edges.Any(edge => _IsExpectedTransfer(edge.From, "Method", "<root>", false, true) && edge.To is FlowInvocation));
Debug.WriteLine(new[] { invokerCfg }.Concat(procedureCfgs.Values).ToDot(callGraph));
}
private ISet <ArrayAccess> _CollectAccesses(string body)
{
var code = TestCodeFactory.CreateCode(body);
var cfg = ControlFlowGraphFactory.Create(code);
return(ArrayAccessCollector.Collect(cfg));
}
public void CodeWithoutCopies()
{
var source = "var x = 0; var y = 2; var z = x + y;";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CopyPropagation.Optimize(code, cfg);
Assert.AreEqual(code, optimized.Code);
Assert.IsFalse(optimized.Changed);
}
public void CodeWithoutCommonSubexpressionsDueToDifferentMethods()
{
var source = "var x = Method1(1); var y = Method2(1); var z = y * 1;";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CommonSubexpressionElimination.Optimize(code, cfg);
Assert.AreEqual(code, optimized.Code);
Assert.IsFalse(optimized.Changed);
}
public void CommonSubexpressionsWithMultipleInvocationsOfTheSameMethodWithDistinctArguments()
{
var source = @"var result = Method(x) + Method(y);";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CommonSubexpressionElimination.Optimize(code, cfg);
Assert.AreEqual(code, optimized.Code);
Assert.IsFalse(optimized.Changed);
}
public void EmptyCode()
{
var source = "";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CopyPropagation.Optimize(code, cfg);
Assert.AreEqual(code, optimized.Code);
Assert.IsFalse(optimized.Changed);
}
public ControlFlowGraph CreateControlFlowGraph(string methodDeclaration)
{
var code = $"class Test {{ {methodDeclaration} }}";
var semanticModel = DocumentFactory.Create().CreateSemanticModel(code);
var method = semanticModel.SyntaxTree.GetRoot().DescendantNodes()
.OfType <MethodDeclarationSyntax>()
.Single();
return(ControlFlowGraphFactory.Create(CodeFactory.CreateMethod(method, semanticModel), true));
}
private ISet <VariableAlias> _CollectAliases(string source)
{
var semanticModel = _documentFactory.CreateSemanticModel(source);
var forStatement = semanticModel.SyntaxTree.GetRoot().DescendantNodes().OfType <ForStatementSyntax>().Single();
var code = CodeFactory.Create(forStatement, semanticModel);
var variableAccesses = VariableAccesses.Collect(code);
var cfg = ControlFlowGraphFactory.Create(code);
return(ExternalArrayAliasCollector.Collect(semanticModel, forStatement, variableAccesses));
}
private bool _HasConflictingArrayAccesses(TLoopStatementSyntax loopStatement, string loopIndex, Code code, VariableAccesses variableAccesses)
{
var optimized = OptimizationRunner.Optimize(code);
code = optimized.Code;
variableAccesses = optimized.Changed ? VariableAccesses.Collect(code) : variableAccesses;
var cfg = ControlFlowGraphFactory.Create(code, true);
var callGraph = CallGraphFactory.Create(cfg, _methods);
var calledMethods = callGraph.Methods.Select(methodName => _methods[methodName]).ToImmutableList();
var aliasAnalysis = AliasAnalysis.Analyze(cfg, callGraph, _methods.Values, _GetAliasesAtLoopEntry(loopStatement, variableAccesses));
return(ArrayAccessVerifier.HasConflictingAccesses(loopIndex, cfg, aliasAnalysis, callGraph, calledMethods));
}
public void CodeWithSameVariableButIntermediateOverwriting()
{
var source = @"
var x = 0;
var y = x;
x = 5;
var z = y;";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CopyPropagation.Optimize(code, cfg);
Assert.AreEqual(code, optimized.Code);
Assert.IsFalse(optimized.Changed);
}
public void CodeWithSameInvocationsButIntermediateValueChange()
{
var source = @"
var x = 5;
var a = Method(x);
x = 2;
var b = Method(x);";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CommonSubexpressionElimination.Optimize(code, cfg);
Assert.AreEqual(code, optimized.Code);
Assert.IsFalse(optimized.Changed);
}
public void SelfAssignmentNegatesOptimization()
{
var source = @"
var x = 5;
var y = 3;
x = x + y;
var a = x + y;";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CommonSubexpressionElimination.Optimize(code, cfg);
Assert.AreEqual(code, optimized.Code);
Assert.IsFalse(optimized.Changed);
}
public void CodeWithInLoopCopy()
{
var source = @"
var x = 0;
var y = x + 1;
for(var i = 0; i < 10; ++i) {
x = x + 1;
}";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CopyPropagation.Optimize(code, cfg);
Assert.AreEqual(code, optimized.Code);
Assert.IsFalse(optimized.Changed);
}
public void CodeWithBranchOnlyCopy()
{
var source = @"
var x = 0;
var y = 2;
if(x > 0) {
y = x;
}
var z = y;";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CopyPropagation.Optimize(code, cfg);
Assert.AreEqual(code, optimized.Code);
Assert.IsFalse(optimized.Changed);
}
public void CodeWithSameInvocationsButInLoop()
{
var source = @"
var x = 5;
var y = 3;
var a = Method(x);
for(var i = 0; i < 10; ++i) {
x = Method(x);
}";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CommonSubexpressionElimination.Optimize(code, cfg);
Assert.AreEqual(code, optimized.Code);
Assert.IsFalse(optimized.Changed);
}
public void CodeWithSameExpressionsButBranchedValueChange()
{
var source = @"
var x = 5;
var y = 3;
var a = y + x;
if(x > y) {
x = 2;
}
var b = y + x;";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CommonSubexpressionElimination.Optimize(code, cfg);
Assert.AreEqual(code, optimized.Code);
Assert.IsFalse(optimized.Changed);
}
public void CommonSubexpressionsInSingleMethodInvocation()
{
var source = @"Method(x + 1, x + 1);";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CommonSubexpressionElimination.Optimize(code, cfg);
Assert.AreNotEqual(code, optimized.Code);
Assert.IsTrue(optimized.Changed);
var expected = @"
DECL $temp_0
$temp_0 = x + 1
DECL $temp_1
$temp_1 = $temp_0
INVOKE Method($temp_0, $temp_1)";
Assert.AreEqual(expected.Trim(), CodeStringifier.Generate(optimized.Code));
}
public void NestedConditionalExpressions()
{
var source = @"var x = a > 0 ? 1 : (a < 0 ? 1 : 0);";
var cfg = ControlFlowGraphFactory.Create(TestCodeFactory.CreateThreeAddressCode(source));
var expected = @"
digraph cfg {
""0"" [ label = ""<End>"" ];
""1"" [ label = ""<Start>"" ];
""2"" [ label = ""Assignment: $temp_0 = $temp_1"" ];
""3"" [ label = ""Assignment: $temp_0 = 1"" ];
""4"" [ label = ""Assignment: $temp_1 = 0"" ];
""5"" [ label = ""Assignment: $temp_1 = 1"" ];
""6"" [ label = ""Assignment: x = $temp_0"" ];
""7"" [ label = ""ConditionalJump: a < 0"" ];
""8"" [ label = ""ConditionalJump: a > 0"" ];
""9"" [ label = ""Declaration: $temp_0"" ];
""10"" [ label = ""Declaration: $temp_1"" ];
""11"" [ label = ""Declaration: x"" ];
""12"" [ label = ""Label"" ];
""13"" [ label = ""Label"" ];
""14"" [ label = ""Label"" ];
""15"" [ label = ""Label"" ];
""1"" -> ""11"" [ label = """" ];
""2"" -> ""15"" [ label = """" ];
""3"" -> ""15"" [ label = """" ];
""4"" -> ""14"" [ label = """" ];
""5"" -> ""14"" [ label = """" ];
""6"" -> ""0"" [ label = """" ];
""7"" -> ""4"" [ label = """" ];
""7"" -> ""13"" [ label = """" ];
""8"" -> ""10"" [ label = """" ];
""8"" -> ""12"" [ label = """" ];
""9"" -> ""8"" [ label = """" ];
""10"" -> ""7"" [ label = """" ];
""11"" -> ""9"" [ label = """" ];
""14"" -> ""2"" [ label = """" ];
""12"" -> ""3"" [ label = """" ];
""13"" -> ""5"" [ label = """" ];
""15"" -> ""6"" [ label = """" ];
}";
Assert.AreEqual(expected.Trim(), cfg.ToDot());
}
public void CodeWithCodeWithSingleCopyUsage()
{
var source = "var x = 0; var y = x; var z = y;";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CopyPropagation.Optimize(code, cfg);
Assert.AreNotEqual(code, optimized.Code);
Assert.IsTrue(optimized.Changed);
var expected = @"
DECL x
x = 0
DECL y
y = x
DECL z
z = x";
Assert.AreEqual(expected.Trim(), CodeStringifier.Generate(optimized.Code));
}
public void CommonSubexpressionsWithMultipleInvocationsOfTheSameMethodWithTheSameArguments()
{
var source = @"var result = Method(x) + Method(x);";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CommonSubexpressionElimination.Optimize(code, cfg);
Assert.AreNotEqual(code, optimized.Code);
Assert.IsTrue(optimized.Changed);
var expected = @"
DECL result
DECL $temp_0
$temp_0 = Method(x)
DECL $temp_1
$temp_1 = $temp_0
result = $temp_0 + $temp_1";
Assert.AreEqual(expected.Trim(), CodeStringifier.Generate(optimized.Code));
}
public void CodeWithSingleCommonInvocation()
{
var source = "var x = 3; var y = Method(x); var z = Method(x);";
var code = TestCodeFactory.CreateThreeAddressCode(source);
var cfg = ControlFlowGraphFactory.Create(code);
var optimized = CommonSubexpressionElimination.Optimize(code, cfg);
Assert.AreNotEqual(code, optimized.Code);
Assert.IsTrue(optimized.Changed);
var expected = @"
DECL x
x = 3
DECL y
y = Method(x)
DECL z
z = y";
Assert.AreEqual(expected.Trim(), CodeStringifier.Generate(optimized.Code));
}
