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Encourage loop cloning #21

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Encourage loop cloning #21

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76d2b30
Support generating simple 'switch' statements
BruceForstall Apr 23, 2025
5eff5d0
Use geometric distribution for case count
BruceForstall Apr 28, 2025
c2aaa6a
Fix `--stats` for use with unspecified extensions list
BruceForstall Apr 28, 2025
3b76afe
Encourage loop cloning
BruceForstall Apr 28, 2025
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2 changes: 1 addition & 1 deletion Fuzzlyn/Fuzzlyn.csproj
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
<PropertyGroup>
<OutputType>Exe</OutputType>
<TargetFramework>net8.0</TargetFramework>
<Version>2.8</Version>
<Version>2.9</Version>
<TieredCompilation>false</TieredCompilation>
<RuntimeIdentifiers>win-x64;win-x86;linux-arm64;linux-arm;osx-arm64</RuntimeIdentifiers>
<LangVersion>preview</LangVersion>
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6 changes: 5 additions & 1 deletion Fuzzlyn/FuzzlynOptions.cs
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Expand Up @@ -63,7 +63,8 @@ internal class FuzzlynOptions
= new TableDistribution(new Dictionary<int, double>
{
[(int)StatementKind.Assignment] = 0.57,
[(int)StatementKind.If] = 0.14,
[(int)StatementKind.If] = 0.135,
[(int)StatementKind.Switch] = 0.005,
[(int)StatementKind.Block] = 0.1,
[(int)StatementKind.Call] = 0.1,
[(int)StatementKind.Throw] = 0.005,
Expand Down Expand Up @@ -109,6 +110,7 @@ internal class FuzzlynOptions
public double PickLiteralFromTableProb { get; set; } = 0.5;
public double ForLoopProb { get; set; } = 0.8;
public double UpCountedLoopProb { get; set; } = 0.5;
public double SmallLoopIterationCountProb { get; set; } = 0.25;

public ProbabilityDistribution SignedIntegerTypicalLiteralDist { get; set; }
= new TableDistribution(new Dictionary<int, double>
Expand Down Expand Up @@ -245,6 +247,8 @@ internal class FuzzlynOptions
[(int)VectorCreationKind.CreateBroadcast] = 0.44,
[(int)VectorCreationKind.CreateScalar] = 0.44,
});

public ProbabilityDistribution SwitchCaseCountDist { get; set; } = new GeometricDistribution(0.2, 5);
}

internal enum AggregateFieldKind
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2 changes: 1 addition & 1 deletion Fuzzlyn/LiteralGenerator.cs
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Expand Up @@ -75,7 +75,7 @@ public static (ExpressionSyntax, ExpressionSyntax) GenPrimitiveLiteralLoopBounds
kind = (TypicalLiteralKind)random.Options.SignedIntegerTypicalLiteralDist.Sample(random.Rng);
}

return primType.Info.GenTypicalLiteralLoopBounds(kind);
return primType.Info.GenTypicalLiteralLoopBounds(kind, random);
}

private static List<int> GenArrayDimensions(Randomizer random, ArrayType at)
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56 changes: 55 additions & 1 deletion Fuzzlyn/Methods/FuncBodyGenerator.cs
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Expand Up @@ -61,7 +61,12 @@ private StatementSyntax GenStatement(bool allowReturn = true)
StatementKind kind =
(StatementKind)Options.StatementTypeDist.Sample(_random.Rng);

if ((kind == StatementKind.Block || kind == StatementKind.If || kind == StatementKind.TryCatch || kind == StatementKind.TryFinally || kind == StatementKind.Loop) &&
if ((kind == StatementKind.Block ||
kind == StatementKind.If ||
kind == StatementKind.Switch ||
kind == StatementKind.TryCatch ||
kind == StatementKind.TryFinally ||
kind == StatementKind.Loop) &&
ShouldRejectRecursion())
continue;

Expand All @@ -81,6 +86,8 @@ private StatementSyntax GenStatement(bool allowReturn = true)
return GenCallStatement(tryExisting: ShouldRejectRecursion());
case StatementKind.If:
return GenIf();
case StatementKind.Switch:
return GenSwitch();
case StatementKind.Throw:
return GenThrow();
case StatementKind.TryCatch:
Expand Down Expand Up @@ -333,6 +340,52 @@ private StatementSyntax GenIf()
return gen;
}

private StatementSyntax GenSwitch()
{
ExpressionSyntax guard;
int attempts = 0;
do
{
guard = GenExpression(new PrimitiveType(SyntaxKind.IntKeyword));
} while (IsLiteralOrCastOfLiteral(guard) && attempts++ < 20);

// C# has a rich 'switch' syntax. Here, for now, generate only a simple switch on int type with dense
// numeric cases, to attempt to get Roslyn to generate a 'switch' IL instruction.

List<SwitchSectionSyntax> switchSections = new();
int caseCount = Options.SwitchCaseCountDist.Sample(_random.Rng);
for (int caseNumber = 0; caseNumber < caseCount; caseNumber++)
{
ExpressionSyntax caseValue = LiteralExpression(SyntaxKind.NumericLiteralExpression, Literal(caseNumber));
switchSections.Add(
SwitchSection()
.WithLabels(
SingletonList<SwitchLabelSyntax>(
CaseSwitchLabel(caseValue)))
.WithStatements(
List<StatementSyntax>(
new StatementSyntax[] {
GenBlock(),
BreakStatement() })));
}

// Add a default case (which is mostly likely what will get executed when we run).
switchSections.Add(
SwitchSection()
.WithLabels(
SingletonList<SwitchLabelSyntax>(
DefaultSwitchLabel()))
.WithStatements(
List<StatementSyntax>(
new StatementSyntax[] {
GenBlock(),
BreakStatement() })));

SyntaxList<SwitchSectionSyntax> switchSectionSyntax = switchSections.ToSyntaxList();
StatementSyntax gen = SwitchStatement(guard, switchSectionSyntax);
return gen;
}

private StatementSyntax GenThrow()
{
Debug.Assert(_tryCatchCount > 0);
Expand Down Expand Up @@ -1341,6 +1394,7 @@ internal enum StatementKind
Assignment,
Call,
If,
Switch,
Return,
Throw,
TryCatch,
Expand Down
3 changes: 3 additions & 0 deletions Fuzzlyn/Program.cs
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Expand Up @@ -191,6 +191,9 @@ private static void Main(string[] args)
}
else if (options.Stats)
{
if (options.GenExtensions == null)
options.GenExtensions = []; // No extension by default with --stats

GenerateProgramsAndGetStats(options);
}
else
Expand Down
20 changes: 20 additions & 0 deletions Fuzzlyn/Reduction/Reducer.cs
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Expand Up @@ -1323,6 +1323,26 @@ private IEnumerable<SyntaxNode> SimplifyIf(SyntaxNode node)
}
}

[Simplifier]
private IEnumerable<SyntaxNode> SimplifySwitch(SyntaxNode node)
{
if (node is not SwitchStatementSyntax @switch)
yield break;

foreach (var section in @switch.Sections)
{
// Remove the 'break;' statement
if (section.Statements.Count > 0)
{
var lastStmt = section.Statements.Last();
if (lastStmt is BreakStatementSyntax)
yield return Block(section.Statements.RemoveAt(section.Statements.Count - 1));
else
yield return Block(section.Statements);
}
}
}

[Simplifier]
private IEnumerable<SyntaxNode> SimplifyFor(SyntaxNode node)
{
Expand Down
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