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thomhurst merged 3 commits into from
Sep 28, 2026
Merged

perf(source-gen): bound generated test-entry methods (data-driven startup JIT -45%) #6909

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23a3ee3
perf(source-gen): build large classes' test entries in bounded fill m…
thomhurst Sep 28, 2026
6694858
Chunk test entries by nested-construction count, not class size
thomhurst Sep 28, 2026
2fcf2b3
Cap total entries per fill method at 100
thomhurst Sep 28, 2026
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173 changes: 148 additions & 25 deletions src/TUnit.Core.SourceGenerator/Generators/TestMetadataGenerator.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -3578,37 +3578,23 @@ private static void GeneratePerClassTestSource(SourceProductionContext context,
// TestEntry<T>[] array — all entries share the same 3 delegates and are built via the
// shared TestEntryFactory so each call site is a single factory call instead of a
// large object initializer (#6227). The factory also builds each entry's MethodMetadata.
writer.AppendLine($"public static readonly global::TUnit.Core.TestEntry<{classGroup.ClassFullyQualified}>[] Entries = new global::TUnit.Core.TestEntry<{classGroup.ClassFullyQualified}>[]");
writer.AppendLine("{");
writer.Indent();
foreach (var method in classGroup.Methods)
var entryType = $"global::TUnit.Core.TestEntry<{classGroup.ClassFullyQualified}>";
if (ShouldChunkEntries(classGroup))
{
WriteChunkedEntries(writer, classGroup, entryType);
}
else
{
writer.AppendLine($"global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<{classGroup.ClassFullyQualified}>(");
writer.AppendLine($"public static readonly {entryType}[] Entries = new {entryType}[]");
writer.AppendLine("{");
writer.Indent();
writer.AppendRaw(method.TestEntryDataFieldsCode);
if (method.TestDataSourcesCode != null)
foreach (var method in classGroup.Methods)
{
writer.AppendLine($"testDataSources: {method.TestDataSourcesCode},");
WriteTestEntryFactoryCall(writer, classGroup, method, ",");
}
if (method.ClassDataSourcesCode != null)
{
writer.AppendLine($"classDataSources: {method.ClassDataSourcesCode},");
}
if (method.DependenciesCode != null)
{
writer.AppendLine($"dependencies: {method.DependenciesCode},");
}
writer.AppendRaw(method.MethodMetadataArgumentsCode);
writer.AppendLine("classMetadata: __classMetadata,");
writer.AppendLine("createInstance: __createInstance,");
writer.AppendLine("invokeBody: __invoke,");
writer.AppendLine($"methodIndex: {method.MethodIndex},");
writer.AppendLine("createAttributes: __attributes,");
writer.AppendLine($"attributeGroupIndex: {method.AttributeGroupIndex}),");
writer.Unindent();
writer.AppendLine("};");
}
writer.Unindent();
writer.AppendLine("};");

writer.Unindent();
writer.AppendLine("}");
Expand All @@ -3634,6 +3620,143 @@ private static void GeneratePerClassTestSource(SourceProductionContext context,
}
}

// Nested-construction entries per __FillEntriesN method. Measured on a 10,000 test
// data-driven suite: 10 minimised total JIT time (5 and 25 were both slower).
private const int NestedEntriesPerFillMethod = 10;

// Total entries per __FillEntriesN method, bounding runs of plain entries in a chunked class.
// Plain entries JIT at roughly linear cost (~6ms per 100-entry plain class), while each extra
// fill method costs roughly 0.15ms (from the 1-entry-per-method measurement), so 100 keeps
// plain runs at the measured plain-class shape for about 2.5% extra method overhead.
private const int EntriesPerFillMethod = 100;

/// <summary>
/// True when an entry builds nested objects (data source attributes, parameter metadata,
/// dependencies, return types) while the outer factory call's arguments are still on the
/// evaluation stack. The JIT spills those pending arguments into fresh temporaries at every
/// nested call, so the temporaries grow with the number of such entries in the method and its
/// JIT time grows faster than linearly (~60ms per 100-entry class for [Arguments] tests).
/// Plain entries pass only constants and cached fields, so they add no spill temporaries.
/// </summary>
private static bool HasNestedConstruction(TestMethodSourceCode method)
{
return method.TestDataSourcesCode != null
|| method.ClassDataSourcesCode != null
|| method.DependenciesCode != null
|| method.MethodMetadataArgumentsCode.Length > 0;
}

/// <summary>
/// True when the class has more nested-construction entries than one fill method holds.
/// Plain entries never trigger chunking, so a large class of plain tests with a few
/// data-driven ones keeps its single array initializer.
/// </summary>
private static bool ShouldChunkEntries(ClassTestGroup classGroup)
{
var nested = 0;
foreach (var method in classGroup.Methods)
{
if (HasNestedConstruction(method) && ++nested > NestedEntriesPerFillMethod)
{
return true;
}
}

return false;
}

/// <summary>
/// Builds the Entries array in fill methods instead of one static constructor array initializer.
/// Each fill method holds at most <see cref="NestedEntriesPerFillMethod"/> nested-construction
/// entries and at most <see cref="EntriesPerFillMethod"/> entries in total. Plain entries are
/// cheap, so runs of them share a fill method with nested entries up to the larger total cap.
/// A new fill method starts when the next entry would exceed either limit.
/// </summary>
private static void WriteChunkedEntries(CodeWriter writer, ClassTestGroup classGroup, string entryType)
{
var methods = classGroup.Methods.AsArray();

// Start index of each fill method, in entry order.
var chunkStarts = new List<int> { 0 };
var nestedInChunk = 0;
var entriesInChunk = 0;
for (var i = 0; i < methods.Length; i++)
{
var nested = HasNestedConstruction(methods[i]);
if (entriesInChunk == EntriesPerFillMethod
|| (nested && nestedInChunk == NestedEntriesPerFillMethod))
{
chunkStarts.Add(i);
nestedInChunk = 0;
entriesInChunk = 0;
}

entriesInChunk++;
if (nested)
{
nestedInChunk++;
}
}

writer.AppendLine($"public static readonly {entryType}[] Entries = __CreateEntries();");
writer.AppendLine($"private static {entryType}[] __CreateEntries()");
writer.AppendLine("{");
writer.Indent();
writer.AppendLine($"var entries = new {entryType}[{methods.Length}];");
for (var chunk = 0; chunk < chunkStarts.Count; chunk++)
{
writer.AppendLine($"__FillEntries{chunk}(entries);");
}
writer.AppendLine("return entries;");
writer.Unindent();
writer.AppendLine("}");

for (var chunk = 0; chunk < chunkStarts.Count; chunk++)
{
writer.AppendLine($"private static void __FillEntries{chunk}({entryType}[] entries)");
writer.AppendLine("{");
writer.Indent();
var end = chunk + 1 < chunkStarts.Count ? chunkStarts[chunk + 1] : methods.Length;
for (var i = chunkStarts[chunk]; i < end; i++)
{
writer.Append($"entries[{i}] = ");
WriteTestEntryFactoryCall(writer, classGroup, methods[i], ";");
}
writer.Unindent();
writer.AppendLine("}");
}
}

/// <summary>
/// Writes one TestEntryFactory.CreateWithClassMetadata call followed by <paramref name="terminator"/>.
/// </summary>
private static void WriteTestEntryFactoryCall(CodeWriter writer, ClassTestGroup classGroup, TestMethodSourceCode method, string terminator)
{
writer.AppendLine($"global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<{classGroup.ClassFullyQualified}>(");
writer.Indent();
writer.AppendRaw(method.TestEntryDataFieldsCode);
if (method.TestDataSourcesCode != null)
{
writer.AppendLine($"testDataSources: {method.TestDataSourcesCode},");
}
if (method.ClassDataSourcesCode != null)
{
writer.AppendLine($"classDataSources: {method.ClassDataSourcesCode},");
}
if (method.DependenciesCode != null)
{
writer.AppendLine($"dependencies: {method.DependenciesCode},");
}
writer.AppendRaw(method.MethodMetadataArgumentsCode);
writer.AppendLine("classMetadata: __classMetadata,");
writer.AppendLine("createInstance: __createInstance,");
writer.AppendLine("invokeBody: __invoke,");
writer.AppendLine($"methodIndex: {method.MethodIndex},");
writer.AppendLine("createAttributes: __attributes,");
writer.AppendLine($"attributeGroupIndex: {method.AttributeGroupIndex}){terminator}");
writer.Unindent();
}

private enum TestReturnPattern
{
Void, // void methods
Expand Down
67 changes: 39 additions & 28 deletions tests/TUnit.Core.SourceGenerator.Tests/ArgsAsArrayTests.Test.verified.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -552,9 +552,17 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
private static readonly global::System.Func<global::System.Type[], object?[], global::TUnit.TestProject.ArgsAsArrayTests> __createInstance = __CreateInstance;
private static readonly global::System.Func<global::TUnit.TestProject.ArgsAsArrayTests, int, object?[], global::System.Threading.CancellationToken, global::System.Threading.Tasks.ValueTask> __invoke = __Invoke;
private static readonly global::System.Func<int, global::System.Attribute[]> __attributes = __Attributes;
public static readonly global::TUnit.Core.TestEntry<global::TUnit.TestProject.ArgsAsArrayTests>[] Entries = new global::TUnit.Core.TestEntry<global::TUnit.TestProject.ArgsAsArrayTests>[]
public static readonly global::TUnit.Core.TestEntry<global::TUnit.TestProject.ArgsAsArrayTests>[] Entries = __CreateEntries();
private static global::TUnit.Core.TestEntry<global::TUnit.TestProject.ArgsAsArrayTests>[] __CreateEntries()
{
global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
var entries = new global::TUnit.Core.TestEntry<global::TUnit.TestProject.ArgsAsArrayTests>[13];
__FillEntries0(entries);
__FillEntries1(entries);
return entries;
}
private static void __FillEntries0(global::TUnit.Core.TestEntry<global::TUnit.TestProject.ArgsAsArrayTests>[] entries)
{
entries[0] = global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
methodName: "Params",
fullyQualifiedName: "TUnit.TestProject.ArgsAsArrayTests.Params",
filePath: "",
Expand All @@ -573,8 +581,8 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
invokeBody: __invoke,
methodIndex: 0,
createAttributes: __attributes,
attributeGroupIndex: 0),
global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
attributeGroupIndex: 0);
entries[1] = global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
methodName: "ParamsEnumerable",
fullyQualifiedName: "TUnit.TestProject.ArgsAsArrayTests.ParamsEnumerable",
filePath: "",
Expand All @@ -593,8 +601,8 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
invokeBody: __invoke,
methodIndex: 1,
createAttributes: __attributes,
attributeGroupIndex: 0),
global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
attributeGroupIndex: 0);
entries[2] = global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
methodName: "Following_Non_Params",
fullyQualifiedName: "TUnit.TestProject.ArgsAsArrayTests.Following_Non_Params",
filePath: "",
Expand All @@ -614,8 +622,8 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
invokeBody: __invoke,
methodIndex: 2,
createAttributes: __attributes,
attributeGroupIndex: 0),
global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
attributeGroupIndex: 0);
entries[3] = global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
methodName: "NonParamsStringArray",
fullyQualifiedName: "TUnit.TestProject.ArgsAsArrayTests.NonParamsStringArray",
filePath: "",
Expand All @@ -636,8 +644,8 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
invokeBody: __invoke,
methodIndex: 3,
createAttributes: __attributes,
attributeGroupIndex: 0),
global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
attributeGroupIndex: 0);
entries[4] = global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
methodName: "NonParamsStringArray_SingleValue",
fullyQualifiedName: "TUnit.TestProject.ArgsAsArrayTests.NonParamsStringArray_SingleValue",
filePath: "",
Expand All @@ -657,8 +665,8 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
invokeBody: __invoke,
methodIndex: 4,
createAttributes: __attributes,
attributeGroupIndex: 0),
global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
attributeGroupIndex: 0);
entries[5] = global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
methodName: "NonParamsStringArray_MultipleValues",
fullyQualifiedName: "TUnit.TestProject.ArgsAsArrayTests.NonParamsStringArray_MultipleValues",
filePath: "",
Expand All @@ -678,8 +686,8 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
invokeBody: __invoke,
methodIndex: 5,
createAttributes: __attributes,
attributeGroupIndex: 0),
global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
attributeGroupIndex: 0);
entries[6] = global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
methodName: "NonParamsIntArray",
fullyQualifiedName: "TUnit.TestProject.ArgsAsArrayTests.NonParamsIntArray",
filePath: "",
Expand All @@ -699,8 +707,8 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
invokeBody: __invoke,
methodIndex: 6,
createAttributes: __attributes,
attributeGroupIndex: 0),
global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
attributeGroupIndex: 0);
entries[7] = global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
methodName: "GenericStringArray",
fullyQualifiedName: "TUnit.TestProject.ArgsAsArrayTests.GenericStringArray",
filePath: "",
Expand All @@ -720,8 +728,8 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
invokeBody: __invoke,
methodIndex: 7,
createAttributes: __attributes,
attributeGroupIndex: 0),
global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
attributeGroupIndex: 0);
entries[8] = global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
methodName: "NonParamsStringArray_BeyondStaticCaseCap",
fullyQualifiedName: "TUnit.TestProject.ArgsAsArrayTests.NonParamsStringArray_BeyondStaticCaseCap",
filePath: "",
Expand All @@ -741,8 +749,8 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
invokeBody: __invoke,
methodIndex: 8,
createAttributes: __attributes,
attributeGroupIndex: 0),
global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
attributeGroupIndex: 0);
entries[9] = global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
methodName: "TrailingArray_ObjectArrayFromMatrix",
fullyQualifiedName: "TUnit.TestProject.ArgsAsArrayTests.TrailingArray_ObjectArrayFromMatrix",
filePath: "",
Expand All @@ -762,8 +770,11 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
invokeBody: __invoke,
methodIndex: 9,
createAttributes: __attributes,
attributeGroupIndex: 0),
global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
attributeGroupIndex: 0);
}
private static void __FillEntries1(global::TUnit.Core.TestEntry<global::TUnit.TestProject.ArgsAsArrayTests>[] entries)
{
entries[10] = global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
methodName: "TrailingParamsArray_ObjectArrayFromMatrix",
fullyQualifiedName: "TUnit.TestProject.ArgsAsArrayTests.TrailingParamsArray_ObjectArrayFromMatrix",
filePath: "",
Expand All @@ -783,8 +794,8 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
invokeBody: __invoke,
methodIndex: 10,
createAttributes: __attributes,
attributeGroupIndex: 0),
global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
attributeGroupIndex: 0);
entries[11] = global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
methodName: "TrailingArray_NonZeroLowerBoundArrayFromMatrix",
fullyQualifiedName: "TUnit.TestProject.ArgsAsArrayTests.TrailingArray_NonZeroLowerBoundArrayFromMatrix",
filePath: "",
Expand All @@ -804,8 +815,8 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
invokeBody: __invoke,
methodIndex: 11,
createAttributes: __attributes,
attributeGroupIndex: 0),
global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
attributeGroupIndex: 0);
entries[12] = global::TUnit.Core.TestEntryFactory.CreateWithClassMetadata<global::TUnit.TestProject.ArgsAsArrayTests>(
methodName: "ParamsObjectArray_ArrayArgumentStaysSingleElement",
fullyQualifiedName: "TUnit.TestProject.ArgsAsArrayTests.ParamsObjectArray_ArrayArgumentStaysSingleElement",
filePath: "",
Expand All @@ -825,8 +836,8 @@ internal static class TUnit_TestProject_ArgsAsArrayTests__TestSource
invokeBody: __invoke,
methodIndex: 12,
createAttributes: __attributes,
attributeGroupIndex: 0),
};
attributeGroupIndex: 0);
}
}
internal static partial class TUnit_TestRegistration
{
Expand Down
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