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Implement cDAC TraverseVirtCallStubHeap and address review polish #127296

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b1ab4d7
Implement cDAC TraverseVirtCallStubHeap and add unit tests
Copilot Apr 21, 2026
0593031
Address TraverseVirtCallStubHeap review feedback
Copilot Apr 24, 2026
68796e2
Polish TraverseVirtCallStubHeap follow-up nits
Copilot Apr 24, 2026
8e41d1b
Adjust virt-call heap key naming per maintainer feedback
Copilot Apr 24, 2026
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12 changes: 11 additions & 1 deletion src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/ISOSDacInterface.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -635,6 +635,16 @@ public struct DacpRCWData
public Interop.BOOL isDisconnected;
}

public enum VCSHeapType : int
{
IndcellHeap = 0,
LookupHeap = 1,
ResolveHeap = 2,
DispatchHeap = 3,
CacheEntryHeap = 4,
VtableHeap = 5
}

[GeneratedComInterface]
[Guid("436f00f2-b42a-4b9f-870c-e73db66ae930")]
public unsafe partial interface ISOSDacInterface
Expand Down Expand Up @@ -818,7 +828,7 @@ public unsafe partial interface ISOSDacInterface
[PreserveSig]
int GetCodeHeapList(ClrDataAddress jitManager, uint count, [In, MarshalUsing(CountElementName = nameof(count)), Out] DacpJitCodeHeapInfo[]? codeHeaps, uint* pNeeded);
[PreserveSig]
int TraverseVirtCallStubHeap(ClrDataAddress pAppDomain, /*VCSHeapType*/ int heaptype, /*VISITHEAP*/ void* pCallback);
int TraverseVirtCallStubHeap(ClrDataAddress pAppDomain, VCSHeapType heaptype, /*VISITHEAP*/ delegate* unmanaged<ulong, nuint, Interop.BOOL, void> pCallback);

// Other
[PreserveSig]
Expand Down
64 changes: 56 additions & 8 deletions src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/SOSDacImpl.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -4668,7 +4668,7 @@ private static void TraverseLoaderHeapDebugCallback(ulong virtualAddress, nuint
}
#endif

private int TraverseLoaderHeapCore(ClrDataAddress loaderHeapAddr, delegate* unmanaged<ulong, nuint, Interop.BOOL, void> pCallback)
private int TraverseLoaderHeapCore(TargetPointer loaderHeapAddr, delegate* unmanaged<ulong, nuint, Interop.BOOL, void> pCallback)
{
int hr = HResults.S_OK;
#if DEBUG
Expand All @@ -4677,13 +4677,12 @@ private int TraverseLoaderHeapCore(ClrDataAddress loaderHeapAddr, delegate* unma
#endif
try
{
if (loaderHeapAddr == 0 || pCallback is null)
if (loaderHeapAddr == TargetPointer.Null || pCallback is null)
throw new ArgumentException();
int iterationMax = 8192;

Contracts.ILoader loader = _target.Contracts.Loader;
TargetPointer heapAddr = loaderHeapAddr.ToTargetPointer(_target);
TargetPointer block = loader.GetFirstLoaderHeapBlock(heapAddr);
TargetPointer block = loader.GetFirstLoaderHeapBlock(loaderHeapAddr);
TargetPointer firstBlock = block;
int i = 0;
while (block != TargetPointer.Null && i++ < iterationMax)
Expand Down Expand Up @@ -4717,7 +4716,7 @@ private int TraverseLoaderHeapCore(ClrDataAddress loaderHeapAddr, delegate* unma

int ISOSDacInterface.TraverseLoaderHeap(ClrDataAddress loaderHeapAddr, delegate* unmanaged<ulong, nuint, Interop.BOOL, void> pCallback)
{
int hr = TraverseLoaderHeapCore(loaderHeapAddr, pCallback);
int hr = TraverseLoaderHeapCore(loaderHeapAddr.ToTargetPointer(_target), pCallback);
#if DEBUG
if (_legacyImpl is not null)
{
Expand Down Expand Up @@ -4862,8 +4861,57 @@ int ISOSDacInterface.TraverseRCWCleanupList(ClrDataAddress cleanupListPtr, deleg
#endif
return hr;
}
int ISOSDacInterface.TraverseVirtCallStubHeap(ClrDataAddress pAppDomain, int heaptype, void* pCallback)
=> LegacyFallbackHelper.CanFallback() && _legacyImpl is not null ? _legacyImpl.TraverseVirtCallStubHeap(pAppDomain, heaptype, pCallback) : HResults.E_NOTIMPL;
int ISOSDacInterface.TraverseVirtCallStubHeap(ClrDataAddress pAppDomain, VCSHeapType heaptype, delegate* unmanaged<ulong, nuint, Interop.BOOL, void> pCallback)
{
int hr = HResults.S_OK;
try
{
// Native DAC only validates pAppDomain here; traversal always uses the global loader allocator.
if (pAppDomain == 0 || pCallback is null)
throw new ArgumentException();

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Contracts.ILoader loader = _target.Contracts.Loader;
TargetPointer globalLoaderAllocator = loader.GetGlobalLoaderAllocator();
IReadOnlyDictionary<string, TargetPointer> heaps = loader.GetLoaderAllocatorHeaps(globalLoaderAllocator);

if (!heaps.ContainsKey("IndcellHeap"))
throw new NullReferenceException();

string? heapName = heaptype switch
{
VCSHeapType.IndcellHeap => "IndcellHeap",
VCSHeapType.CacheEntryHeap => "CacheEntryHeap",
_ => throw new ArgumentException(),
};

if (heaps.TryGetValue(heapName, out TargetPointer heap) && heap != TargetPointer.Null)
{
hr = TraverseLoaderHeapCore(heap, pCallback);
}
}
catch (System.Exception ex)
{
hr = ex.HResult;
}

#if DEBUG
if (_legacyImpl is not null)
{
int cdacCount = DebugTraverseLoaderHeapBlocks.Count;
delegate* unmanaged<ulong, nuint, Interop.BOOL, void> debugCallbackPtr = &TraverseLoaderHeapDebugCallback;
int hrLocal = _legacyImpl.TraverseVirtCallStubHeap(pAppDomain, heaptype, debugCallbackPtr);
Debug.ValidateHResult(hr, hrLocal);
if (hr == HResults.S_OK || hr == HResults.S_FALSE)
{
Debug.Assert(DebugTraverseLoaderHeapBlocks.Count == 0,
$"cDAC found {cdacCount} blocks, DAC matched {_debugTraverseLoaderDebugCount}, {DebugTraverseLoaderHeapBlocks.Count} unmatched");
Debug.Assert(_debugTraverseLoaderDebugCount == (uint)cdacCount,
$"cDAC: {cdacCount} blocks, DAC: {_debugTraverseLoaderDebugCount} blocks");
}
}
#endif
return hr;
}
#endregion ISOSDacInterface

#region ISOSDacInterface2
Expand Down Expand Up @@ -6207,7 +6255,7 @@ int ISOSDacInterface12.GetGlobalAllocationContext(ClrDataAddress* allocPtr, ClrD

int ISOSDacInterface13.TraverseLoaderHeap(ClrDataAddress loaderHeapAddr, /*LoaderHeapKind*/ int kind, /*VISITHEAP*/ delegate* unmanaged<ulong, nuint, Interop.BOOL, void> pCallback)
{
int hr = TraverseLoaderHeapCore(loaderHeapAddr, pCallback);
int hr = TraverseLoaderHeapCore(loaderHeapAddr.ToTargetPointer(_target), pCallback);
#if DEBUG
if (_legacyImpl13 is not null)
{
Expand Down
171 changes: 171 additions & 0 deletions src/native/managed/cdac/tests/LoaderTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -167,6 +167,15 @@ public void TryGetSimpleName_InvalidUtf8(MockTarget.Architecture arch)
["CacheEntryHeap"] = new(0x9000),
};

private const VCSHeapType VCSHeapTypeIndcell = VCSHeapType.IndcellHeap;
private const VCSHeapType VCSHeapTypeCacheEntry = VCSHeapType.CacheEntryHeap;
private const VCSHeapType InvalidVCSHeapType = (VCSHeapType)99;

[UnmanagedCallersOnly]
private static void VisitHeapNoOp(ulong address, nuint size, Interop.BOOL isCurrent)
{
}

private static ISOSDacInterface13 CreateSOSDacInterface13ForHeapTests(MockTarget.Architecture arch)
{
var targetBuilder = new TestPlaceholderTarget.Builder(arch);
Expand Down Expand Up @@ -207,6 +216,168 @@ private static ISOSDacInterface13 CreateSOSDacInterface13ForHeapTests(MockTarget
return new SOSDacImpl(target, null);
}

private static (ISOSDacInterface Interface, Mock<ILoader> Loader) CreateSOSDacInterfaceForVirtCallHeapTests(MockTarget.Architecture arch)
{
Mock<ILoader> loader = new(MockBehavior.Strict);
TargetPointer globalLoaderAllocator = new(0x100);
loader.Setup(l => l.GetGlobalLoaderAllocator()).Returns(globalLoaderAllocator);

var target = new TestPlaceholderTarget.Builder(arch)
.AddMockContract<ILoader>(loader.Object)
.Build();

return (new SOSDacImpl(target, null), loader);
}

[Theory]
[ClassData(typeof(MockTarget.StdArch))]
public void TraverseVirtCallStubHeap_IndcellHeap_Traverses(MockTarget.Architecture arch)
{
(ISOSDacInterface impl, Mock<ILoader> loader) = CreateSOSDacInterfaceForVirtCallHeapTests(arch);

TargetPointer indcellHeap = new(0x8000);
TargetPointer firstBlock = new(0x8100);
var heaps = new Dictionary<string, TargetPointer>
{
["IndcellHeap"] = indcellHeap,
};
loader.Setup(l => l.GetLoaderAllocatorHeaps(new TargetPointer(0x100)))
.Returns((IReadOnlyDictionary<string, TargetPointer>)heaps);
loader.Setup(l => l.GetFirstLoaderHeapBlock(indcellHeap)).Returns(firstBlock);
loader.Setup(l => l.GetLoaderHeapBlockData(firstBlock)).Returns(new LoaderHeapBlockData
{
Address = new TargetPointer(0x9000),
Size = new TargetNUInt(0x40),
NextBlock = TargetPointer.Null,
});

delegate* unmanaged<ulong, nuint, Interop.BOOL, void> callback = &VisitHeapNoOp;
int hr = impl.TraverseVirtCallStubHeap(new ClrDataAddress(0x1), VCSHeapTypeIndcell, callback);

Assert.Equal(HResults.S_OK, hr);
loader.Verify(l => l.GetFirstLoaderHeapBlock(indcellHeap), Times.Once());
loader.Verify(l => l.GetLoaderHeapBlockData(firstBlock), Times.Once());
}

[Theory]
[ClassData(typeof(MockTarget.StdArch))]
public void TraverseVirtCallStubHeap_CacheEntryHeap_Traverses(MockTarget.Architecture arch)
{
(ISOSDacInterface impl, Mock<ILoader> loader) = CreateSOSDacInterfaceForVirtCallHeapTests(arch);

TargetPointer cacheEntryHeap = new(0x9000);
TargetPointer firstBlock = new(0x9100);
var heaps = new Dictionary<string, TargetPointer>
{
["IndcellHeap"] = new TargetPointer(0x8000),
["CacheEntryHeap"] = cacheEntryHeap,
};
loader.Setup(l => l.GetLoaderAllocatorHeaps(new TargetPointer(0x100)))
.Returns((IReadOnlyDictionary<string, TargetPointer>)heaps);
loader.Setup(l => l.GetFirstLoaderHeapBlock(cacheEntryHeap)).Returns(firstBlock);
loader.Setup(l => l.GetLoaderHeapBlockData(firstBlock)).Returns(new LoaderHeapBlockData
{
Address = new TargetPointer(0xA000),
Size = new TargetNUInt(0x40),
NextBlock = TargetPointer.Null,
});

delegate* unmanaged<ulong, nuint, Interop.BOOL, void> callback = &VisitHeapNoOp;
int hr = impl.TraverseVirtCallStubHeap(new ClrDataAddress(0x1), VCSHeapTypeCacheEntry, callback);

Assert.Equal(HResults.S_OK, hr);
loader.Verify(l => l.GetFirstLoaderHeapBlock(cacheEntryHeap), Times.Once());
loader.Verify(l => l.GetLoaderHeapBlockData(firstBlock), Times.Once());
}

[Theory]
[ClassData(typeof(MockTarget.StdArch))]
public void TraverseVirtCallStubHeap_NoVirtualCallStubManager_ReturnsEPointer(MockTarget.Architecture arch)
{
(ISOSDacInterface impl, Mock<ILoader> loader) = CreateSOSDacInterfaceForVirtCallHeapTests(arch);

loader.Setup(l => l.GetLoaderAllocatorHeaps(new TargetPointer(0x100)))
.Returns((IReadOnlyDictionary<string, TargetPointer>)new Dictionary<string, TargetPointer>());

delegate* unmanaged<ulong, nuint, Interop.BOOL, void> callback = &VisitHeapNoOp;
int hr = impl.TraverseVirtCallStubHeap(new ClrDataAddress(0x1), VCSHeapTypeIndcell, callback);

Assert.Equal(HResults.E_POINTER, hr);
}

[Theory]
[ClassData(typeof(MockTarget.StdArch))]
public void TraverseVirtCallStubHeap_CacheEntryMissing_ReturnsSOk(MockTarget.Architecture arch)
{
(ISOSDacInterface impl, Mock<ILoader> loader) = CreateSOSDacInterfaceForVirtCallHeapTests(arch);

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TargetPointer indcellHeap = new(0x8000);
loader.Setup(l => l.GetLoaderAllocatorHeaps(new TargetPointer(0x100)))
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.Returns((IReadOnlyDictionary<string, TargetPointer>)new Dictionary<string, TargetPointer>
{
["IndcellHeap"] = indcellHeap,
});

delegate* unmanaged<ulong, nuint, Interop.BOOL, void> callback = &VisitHeapNoOp;
int hr = impl.TraverseVirtCallStubHeap(new ClrDataAddress(0x1), VCSHeapTypeCacheEntry, callback);

Assert.Equal(HResults.S_OK, hr);
loader.Verify(l => l.GetFirstLoaderHeapBlock(It.IsAny<TargetPointer>()), Times.Never());
}

[Theory]
[ClassData(typeof(MockTarget.StdArch))]
public void TraverseVirtCallStubHeap_InvalidHeapType_ReturnsEInvalidArg(MockTarget.Architecture arch)
{
(ISOSDacInterface impl, Mock<ILoader> loader) = CreateSOSDacInterfaceForVirtCallHeapTests(arch);

loader.Setup(l => l.GetLoaderAllocatorHeaps(new TargetPointer(0x100)))
.Returns((IReadOnlyDictionary<string, TargetPointer>)new Dictionary<string, TargetPointer>
{
["IndcellHeap"] = new TargetPointer(0x8000),
});

delegate* unmanaged<ulong, nuint, Interop.BOOL, void> callback = &VisitHeapNoOp;
int hr = impl.TraverseVirtCallStubHeap(new ClrDataAddress(0x1), InvalidVCSHeapType, callback);

Assert.Equal(HResults.E_INVALIDARG, hr);
}

[Theory]
[ClassData(typeof(MockTarget.StdArch))]
public void TraverseVirtCallStubHeap_InvalidArguments_ReturnsEInvalidArg(MockTarget.Architecture arch)
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{
(ISOSDacInterface impl, Mock<ILoader> loader) = CreateSOSDacInterfaceForVirtCallHeapTests(arch);

loader.Setup(l => l.GetLoaderAllocatorHeaps(new TargetPointer(0x100)))
.Returns((IReadOnlyDictionary<string, TargetPointer>)new Dictionary<string, TargetPointer>
{
["IndcellHeap"] = new TargetPointer(0x8000),
});

delegate* unmanaged<ulong, nuint, Interop.BOOL, void> callback = &VisitHeapNoOp;
int hr = impl.TraverseVirtCallStubHeap(new ClrDataAddress(0), VCSHeapTypeIndcell, callback);

Assert.Equal(HResults.E_INVALIDARG, hr);
}

[Theory]
[ClassData(typeof(MockTarget.StdArch))]
public void TraverseVirtCallStubHeap_NullCallback_ReturnsEInvalidArg(MockTarget.Architecture arch)
{
(ISOSDacInterface impl, Mock<ILoader> loader) = CreateSOSDacInterfaceForVirtCallHeapTests(arch);

loader.Setup(l => l.GetLoaderAllocatorHeaps(new TargetPointer(0x100)))
.Returns((IReadOnlyDictionary<string, TargetPointer>)new Dictionary<string, TargetPointer>
{
["IndcellHeap"] = new TargetPointer(0x8000),
});

int hr = impl.TraverseVirtCallStubHeap(new ClrDataAddress(0x1), VCSHeapTypeIndcell, null);

Assert.Equal(HResults.E_INVALIDARG, hr);
}

[Theory]
[ClassData(typeof(MockTarget.StdArch))]
public void GetLoaderAllocatorHeapNames_GetCount(MockTarget.Architecture arch)
Expand Down
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