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Add cDac contract for ResolveFrameHelper #129261

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0d9f706
Implement cDAC ResolveHelperFrame handling
leculver Jun 8, 2026
9f19732
Fix cDAC ResolveHelperFrame tests
leculver Jun 10, 2026
b6c8c7a
Separate ResolveHelperFrame return address handling
leculver Jun 10, 2026
3d2fcc9
Document ResolveHelperFrame in StackWalk data contract
leculver Jun 11, 2026
2a8047e
Add ARM64 coverage for ResolveHelperFrame context handling
leculver Jun 11, 2026
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4 changes: 4 additions & 0 deletions docs/design/datacontracts/StackWalk.md
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Expand Up@@ -103,6 +103,7 @@ This contract depends on the following descriptors:
| `SoftwareExceptionFrame` | `ReturnAddress` | Return address saved in Frame |
| `FramedMethodFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock |
| `FramedMethodFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `ResolveHelperFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock (only present when `FEATURE_RESOLVE_HELPER_DISPATCH` is defined) |

@jkotasjkotasJun 18, 2026

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This was test-only code for Native AOT. I do not think it is currently reachable.

Are you able to actually hit this in tests?

@leculverleculverJun 18, 2026•
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No, this is from code review only. I mostly want to make sure that we aren't missing a cDac contract for some scenario which would require servicing later. This seems to be the only coreclr!Frame that isn't wrapped. If this is pure test code that will never ship, I will close this PR. That wasn't obvious from source inspection.

@leculverleculverJun 18, 2026

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Scanning through it looks like DOTNET_JitForceControlFlowGuard=1 can still reach this, and this code is dac-ized in the legacy dac. Seems like it would be safer to wrap it in case we need to debug something where it shows up.

I'm happy to close without merging if you disagree though.

@jkotasjkotasJun 21, 2026

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I do not think it is reachable currently.

ResolveHelperFrame is only used by VSD_ResolveWorkerForInterfaceLookupSlot. VSD_ResolveWorkerForInterfaceLookupSlot is only called by JIT_InterfaceLookupForSlot. JIT_InterfaceLookupForSlot ID is CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT.CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT is never emitted by the JIT currently.

I think you can delete this whole chain if you would like.

@leculverleculverJun 21, 2026

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Thanks! I'll close this one and open a new one to do exactly that.

| `StubDispatchFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `StubDispatchFrame` | `RepresentativeMTPtr` | Pointer to Frame's method table pointer |
| `StubDispatchFrame` | `RepresentativeSlot` | Frame's method table slot |
Expand DownExpand Up@@ -401,6 +402,9 @@ The following Frame types also use this mechanism:
* CallCountingHelperFrame
* ExternalMethodFrame
* DynamicHelperFrame
* ResolveHelperFrame

`ResolveHelperFrame` additionally restores the argument registers stored in the `TransitionBlock` on all platforms (not just ARM), because the virtual stub dispatch resolve helper relies on the original argument registers to perform dispatch resolution. This mirrors native `ResolveHelperFrame::UpdateRegDisplay`. It is only present when the runtime is built with `FEATURE_RESOLVE_HELPER_DISPATCH`; when the feature is absent its type descriptor and Frame identifier are not emitted, so no Frame is ever classified as a `ResolveHelperFrame`.

#### FuncEvalFrame

Expand Down
7 changes: 7 additions & 0 deletions src/coreclr/vm/datadescriptor/datadescriptor.inc
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Expand Up@@ -1098,6 +1098,13 @@ CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, TransitionBlockPtr, cdac_data<Fram
CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, MethodDescPtr, cdac_data<FramedMethodFrame>::MethodDescPtr)
CDAC_TYPE_END(FramedMethodFrame)

#ifdef FEATURE_RESOLVE_HELPER_DISPATCH
CDAC_TYPE_BEGIN(ResolveHelperFrame)
CDAC_TYPE_SIZE(sizeof(ResolveHelperFrame))
CDAC_TYPE_FIELD(ResolveHelperFrame, T_POINTER, TransitionBlockPtr, cdac_data<ResolveHelperFrame>::TransitionBlockPtr)
CDAC_TYPE_END(ResolveHelperFrame)
#endif // FEATURE_RESOLVE_HELPER_DISPATCH

#ifdef FEATURE_INTERPRETER
CDAC_TYPE_BEGIN(InterpreterFrame)
CDAC_TYPE_INDETERMINATE(InterpreterFrame)
Expand Down
8 changes: 8 additions & 0 deletions src/coreclr/vm/frames.h
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Expand Up@@ -951,6 +951,14 @@ class ResolveHelperFrame : public TransitionFrame
}

void UpdateRegDisplay_Impl(const PREGDISPLAY, bool updateFloats = false);

friend struct cdac_data<ResolveHelperFrame>;
};

template<>
struct cdac_data<ResolveHelperFrame>
{
static constexpr size_t TransitionBlockPtr = offsetof(ResolveHelperFrame, m_pTransitionBlock);
};

#endif // FEATURE_RESOLVE_HELPER_DISPATCH
Expand Down
6 changes: 6 additions & 0 deletions ...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/AMD64FrameHandler.cs
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Expand Up@@ -58,4 +58,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
// that does not support holding any extended state.
_holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
}

public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
{
base.HandleResolveHelperFrame(frame);
UpdateArgumentRegisters(frame.TransitionBlockPtr);
}
}
6 changes: 6 additions & 0 deletions ...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARM64FrameHandler.cs
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Expand Up@@ -48,4 +48,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
// that does not support holding any extended state.
_holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
}

public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
{
base.HandleResolveHelperFrame(frame);
UpdateArgumentRegisters(frame.TransitionBlockPtr);
}
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}
7 changes: 5 additions & 2 deletions ...nostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARMFrameHandler.cs
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Expand Up@@ -46,11 +46,14 @@ public override void HandleInlinedCallFrame(InlinedCallFrame inlinedCallFrame)
}

public override void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
=> HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

public override void HandleTransitionBlock(TargetPointer transitionBlockPtr)
{
// Call the base method to handle common logic
base.HandleTransitionFrame(framedMethodFrame);
base.HandleTransitionBlock(transitionBlockPtr);

Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);

// On ARM, TransitionFrames update the argument registers
Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
Expand Down
17 changes: 15 additions & 2 deletions ...ostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/BaseFrameHandler.cs
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Expand Up@@ -42,20 +42,33 @@ public virtual void HandleSoftwareExceptionFrame(SoftwareExceptionFrame software
}

public virtual void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
=> HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

public virtual void HandleResolveHelperFrame(ResolveHelperFrame frame)
=> HandleTransitionBlock(frame.TransitionBlockPtr);

public virtual void HandleTransitionBlock(TargetPointer transitionBlockPtr)
{
Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
if (_target.GetTypeInfo(DataType.TransitionBlock).Size is not uint transitionBlockSize)
{
throw new InvalidOperationException("TransitionBlock size is not set");
}

_context.InstructionPointer = transitionBlock.ReturnAddress;
_context.StackPointer = framedMethodFrame.TransitionBlockPtr + transitionBlockSize;
_context.StackPointer = transitionBlockPtr + transitionBlockSize;

Data.CalleeSavedRegisters calleeSavedRegisters = _target.ProcessedData.GetOrAdd<Data.CalleeSavedRegisters>(transitionBlock.CalleeSavedRegisters);
UpdateFromRegisterDict(calleeSavedRegisters.Registers);
}

protected void UpdateArgumentRegisters(TargetPointer transitionBlockPtr)
{
Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
UpdateFromRegisterDict(argumentRegisters.Registers);
}

public virtual void HandleFuncEvalFrame(FuncEvalFrame funcEvalFrame)
{
Data.DebuggerEval debuggerEval = _target.ProcessedData.GetOrAdd<Data.DebuggerEval>(funcEvalFrame.DebuggerEvalPtr);
Expand Down
22 changes: 19 additions & 3 deletions ...iagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/FrameHelpers.cs
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Expand Up@@ -24,6 +24,7 @@ internal enum FrameType
ExternalMethodFrame,
DynamicHelperFrame,
InterpreterFrame,
ResolveHelperFrame,

FuncEvalFrame,

Expand DownExpand Up@@ -141,7 +142,8 @@ public TargetPointer GetMethodDescPtr(TargetPointer framePtr)
/// </summary>
public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext context)
{
switch (GetFrameType(frame.Identifier))
FrameType frameType = GetFrameType(frame.Identifier);
switch (frameType)
{
case FrameType.InlinedCallFrame:
Data.InlinedCallFrame inlinedCallFrame = _target.ProcessedData.GetOrAdd<Data.InlinedCallFrame>(frame.Address);
Expand All@@ -166,6 +168,11 @@ public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext co
GetFrameHandler(context).HandleTransitionFrame(framedMethodFrame);
return;

case FrameType.ResolveHelperFrame:
Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
GetFrameHandler(context).HandleResolveHelperFrame(resolveHelperFrame);
return;

case FrameType.InterpreterFrame:
{
// Mirrors native InterpreterFrame::SetContextToInterpMethodContextFrame
Expand DownExpand Up@@ -232,9 +239,18 @@ public TargetPointer GetReturnAddress(Data.Frame frame)
case FrameType.CallCountingHelperFrame:
case FrameType.ExternalMethodFrame:
case FrameType.DynamicHelperFrame:
Data.FramedMethodFrame fmf = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(fmf.TransitionBlockPtr);
{
Data.FramedMethodFrame framedMethodFrame = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
return tb.ReturnAddress;
}

case FrameType.ResolveHelperFrame:
{
Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(resolveHelperFrame.TransitionBlockPtr);
return tb.ReturnAddress;
}

// SoftwareExceptionFrame: stored m_ReturnAddress
case FrameType.SoftwareExceptionFrame:
Expand Down
2 changes: 2 additions & 0 deletions ...s.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/IPlatformFrameHandler.cs
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Expand Up@@ -14,6 +14,8 @@ internal interface IPlatformFrameHandler
void HandleInlinedCallFrame(Data.InlinedCallFrame frame);
void HandleSoftwareExceptionFrame(Data.SoftwareExceptionFrame frame);
void HandleTransitionFrame(Data.FramedMethodFrame frame);
void HandleTransitionBlock(TargetPointer transitionBlockPtr);
void HandleResolveHelperFrame(Data.ResolveHelperFrame frame);
void HandleFuncEvalFrame(Data.FuncEvalFrame frame);
void HandleResumableFrame(Data.ResumableFrame frame);
void HandleFaultingExceptionFrame(Data.FaultingExceptionFrame frame);
Expand Down
3 changes: 2 additions & 1 deletion ...dac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/StackWalk_1.cs
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Expand Up@@ -77,7 +77,8 @@ public bool IsCurrentFrameResumable()
// HijackFrame should be conditioned on the target architecture.
return ft is FrameType.ResumableFrame
or FrameType.RedirectedThreadFrame
or FrameType.HijackFrame;
or FrameType.HijackFrame
or FrameType.ResolveHelperFrame;
}

/// <summary>
Expand Down
10 changes: 10 additions & 0 deletions ...cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/ResolveHelperFrame.cs
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@@ -0,0 +1,10 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

namespace Microsoft.Diagnostics.DataContractReader.Data;

[CdacType(nameof(DataType.ResolveHelperFrame))]
internal partial class ResolveHelperFrame : IData<ResolveHelperFrame>
{
[Field] public TargetPointer TransitionBlockPtr { get; }
}
1 change: 1 addition & 0 deletions src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/DataType.cs
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Expand Up@@ -166,6 +166,7 @@ public enum DataType
InlinedCallFrame,
SoftwareExceptionFrame,
FramedMethodFrame,
ResolveHelperFrame,
Comment thread
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FuncEvalFrame,
ResumableFrame,
FaultingExceptionFrame,
Expand Down
2 changes: 1 addition & 1 deletion src/native/managed/cdac/tests/TestInfrastructure/TestPlaceholderTarget.cs
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Expand Up@@ -546,7 +546,7 @@ public override Target.TypeInfo GetTypeInfo(string typeName)
public override bool TryGetTypeInfo(string typeName, out Target.TypeInfo info)
=> _typeInfoCache.TryGetValue(typeName, out info);

public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => throw new NotImplementedException();
public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => false;

public override Target.IDataCache ProcessedData => _dataCache;
public override ContractRegistry Contracts => _contractRegistry;
Expand Down
103 changes: 102 additions & 1 deletion src/native/managed/cdac/tests/UnitTests/MockDescriptors/MockDescriptors.Frame.cs
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Expand Up@@ -76,6 +76,22 @@ public ulong MethodDescPtr
}
}

internal sealed class MockResolveHelperFrame : MockFrame
{
private const string TransitionBlockPtrFieldName = "TransitionBlockPtr";

public static Layout<MockResolveHelperFrame> CreateLayout(Layout<MockFrame> baseLayout)
=> new SequentialLayoutBuilder("ResolveHelperFrame", baseLayout.Architecture, baseLayout)
.AddPointerField(TransitionBlockPtrFieldName)
.Build<MockResolveHelperFrame>();

public ulong TransitionBlockPtr
{
get => ReadPointerField(TransitionBlockPtrFieldName);
set => WritePointerField(TransitionBlockPtrFieldName, value);
}
}

internal sealed class MockFuncEvalFrame : MockFrame
{
// Mirrors the cDAC FuncEvalFrame data class which only reads DebuggerEvalPtr.
Expand DownExpand Up@@ -142,6 +158,59 @@ public ulong TargetContextPtr
}
}

internal sealed class MockTransitionBlock : TypedView
{
private const string ReturnAddressFieldName = "ReturnAddress";
private const string CalleeSavedRegistersFieldName = "CalleeSavedRegisters";
private const string ArgumentRegistersFieldName = "ArgumentRegisters";
private const string FirstGCRefMapSlotFieldName = "FirstGCRefMapSlot";

public static Layout<MockTransitionBlock> CreateLayout(MockTarget.Architecture architecture, Layout<MockRegisterSet> calleeSavedRegistersLayout, Layout<MockRegisterSet> argumentRegistersLayout)
=> new SequentialLayoutBuilder("TransitionBlock", architecture)
.AddPointerField(ReturnAddressFieldName)
.AddField(CalleeSavedRegistersFieldName, calleeSavedRegistersLayout.Size)
.AddField(ArgumentRegistersFieldName, argumentRegistersLayout.Size)
.AddPointerField(FirstGCRefMapSlotFieldName)
.Build<MockTransitionBlock>();

public ulong ReturnAddress
{
get => ReadPointerField(ReturnAddressFieldName);
set => WritePointerField(ReturnAddressFieldName, value);
}

public ulong CalleeSavedRegister
{
get => ReadPointerField(CalleeSavedRegistersFieldName);
set => WritePointerField(CalleeSavedRegistersFieldName, value);
}

public ulong ArgumentRegister
{
get => ReadPointerField(ArgumentRegistersFieldName);
set => WritePointerField(ArgumentRegistersFieldName, value);
}
}

internal sealed class MockRegisterSet : TypedView
{
public const string CalleeSavedRegisterName = "rbx";
public const string ArgumentRegisterName = "rcx";
public const string Arm64CalleeSavedRegisterName = "x19";
public const string Arm64ArgumentRegisterName = "x0";

public static Layout<MockRegisterSet> CreateLayout(MockTarget.Architecture architecture, string name)
=> new SequentialLayoutBuilder(name, architecture)
.AddPointerField(name)
.Build<MockRegisterSet>();

public ulong Register
{
get => ReadPointerField(Layout.Name);
set => WritePointerField(Layout.Name, value);
}
}

/// <summary>
/// Helper for building a Frame chain in the mock target memory. The Frame chain is
/// terminated with the FRAME_TOP sentinel (~0 sized to the target pointer width).
Expand All@@ -168,6 +237,7 @@ internal sealed class MockFrameBuilder
public const ulong InterpreterFrameIdentifierValue = 0x0001_F009;
public const ulong HijackFrameIdentifierValue = 0x0001_F00A;
public const ulong RedirectedThreadFrameIdentifierValue = 0x0001_F00B;
public const ulong ResolveHelperFrameIdentifierValue = 0x0001_F00C;

private readonly MockMemorySpace.Builder _builder;
private readonly MockMemorySpace.BumpAllocator _allocator;
Expand All@@ -177,16 +247,25 @@ internal sealed class MockFrameBuilder
public Layout<MockFrame> FrameLayout { get; }
public Layout<MockInlinedCallFrame> InlinedCallFrameLayout { get; }
public Layout<MockFramedMethodFrame> FramedMethodFrameLayout { get; }
public Layout<MockResolveHelperFrame> ResolveHelperFrameLayout { get; }
public Layout<MockFuncEvalFrame> FuncEvalFrameLayout { get; }
public Layout<MockDebuggerEval> DebuggerEvalLayout { get; }
public Layout<MockResumableFrame> ResumableFrameLayout { get; }
public Layout<MockTransitionBlock> TransitionBlockLayout { get; }
public Layout<MockRegisterSet> CalleeSavedRegistersLayout { get; }
public Layout<MockRegisterSet> ArgumentRegistersLayout { get; }

public MockFrameBuilder(MockMemorySpace.Builder builder)
: this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd))
{
}

public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange)
public MockFrameBuilder(MockMemorySpace.Builder builder, string calleeSavedRegisterName, string argumentRegisterName)
: this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd), calleeSavedRegisterName, argumentRegisterName)
{
}

public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange, string? calleeSavedRegisterName = null, string? argumentRegisterName = null)
{
_builder = builder;
_helpers = builder.TargetTestHelpers;
Expand All@@ -196,9 +275,13 @@ public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End
FrameLayout = MockFrame.CreateLayout(_helpers.Arch);
InlinedCallFrameLayout = MockInlinedCallFrame.CreateLayout(FrameLayout);
FramedMethodFrameLayout = MockFramedMethodFrame.CreateLayout(FrameLayout);
ResolveHelperFrameLayout = MockResolveHelperFrame.CreateLayout(FrameLayout);
FuncEvalFrameLayout = MockFuncEvalFrame.CreateLayout(FrameLayout);
DebuggerEvalLayout = MockDebuggerEval.CreateLayout(_helpers.Arch);
ResumableFrameLayout = MockResumableFrame.CreateLayout(FrameLayout);
CalleeSavedRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, calleeSavedRegisterName ?? MockRegisterSet.CalleeSavedRegisterName);
ArgumentRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, argumentRegisterName ?? MockRegisterSet.ArgumentRegisterName);
TransitionBlockLayout = MockTransitionBlock.CreateLayout(_helpers.Arch, CalleeSavedRegistersLayout, ArgumentRegistersLayout);
}

public ulong FrameTopTerminator => _terminator;
Expand DownExpand Up@@ -239,6 +322,24 @@ public MockFramedMethodFrame AddFramedMethodFrame(ulong methodDescPtr)
return frame;
}

public MockResolveHelperFrame AddResolveHelperFrame(ulong transitionBlockPtr)
{
MockResolveHelperFrame frame = ResolveHelperFrameLayout.Create(_allocator.Allocate((ulong)ResolveHelperFrameLayout.Size, "ResolveHelperFrame"));
frame.Identifier = ResolveHelperFrameIdentifierValue;
frame.Next = _terminator;
frame.TransitionBlockPtr = transitionBlockPtr;
return frame;
}

public MockTransitionBlock AddTransitionBlock(ulong returnAddress, ulong calleeSavedRegister, ulong argumentRegister)
{
MockTransitionBlock transitionBlock = TransitionBlockLayout.Create(_allocator.Allocate((ulong)TransitionBlockLayout.Size, "TransitionBlock"));
transitionBlock.ReturnAddress = returnAddress;
transitionBlock.CalleeSavedRegister = calleeSavedRegister;
transitionBlock.ArgumentRegister = argumentRegister;
return transitionBlock;
}

public MockResumableFrame AddRedirectedThreadFrame(ulong targetContextPtr)
{
MockResumableFrame frame = ResumableFrameLayout.Create(_allocator.Allocate((ulong)ResumableFrameLayout.Size, "RedirectedThreadFrame"));
Expand Down
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Add cDac contract for ResolveFrameHelper by leculver · Pull Request #129261 · dotnet/runtime · GitHub
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Add cDac contract for ResolveFrameHelper
#129261
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0d9f706

Implement cDAC ResolveHelperFrame handling


leculver Jun 8, 2026
9f19732

Fix cDAC ResolveHelperFrame tests


leculver Jun 10, 2026
b6c8c7a

Separate ResolveHelperFrame return address handling


leculver Jun 10, 2026
3d2fcc9

Document ResolveHelperFrame in StackWalk data contract


leculver Jun 11, 2026
2a8047e

Add ARM64 coverage for ResolveHelperFrame context handling


leculver Jun 11, 2026

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4 changes: 4 additions & 0 deletions
docs/design/datacontracts/StackWalk.md

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Original file line numberDiff line numberDiff line change
Expand Up@@ -103,6 +103,7 @@ This contract depends on the following descriptors:
| `SoftwareExceptionFrame` | `ReturnAddress` | Return address saved in Frame |
| `FramedMethodFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock |
| `FramedMethodFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `ResolveHelperFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock (only present when `FEATURE_RESOLVE_HELPER_DISPATCH` is defined) |
@jkotasjkotasJun 18, 2026

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This was test-only code for Native AOT. I do not think it is currently reachable.
Are you able to actually hit this in tests?
@leculverleculverJun 18, 2026•

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No, this is from code review only. I mostly want to make sure that we aren't missing a cDac contract for some scenario which would require servicing later. This seems to be the only coreclr!Frame that isn't wrapped. If this is pure test code that will never ship, I will close this PR. That wasn't obvious from source inspection.
@leculverleculverJun 18, 2026

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Scanning through it looks like DOTNET_JitForceControlFlowGuard=1 can still reach this, and this code is dac-ized in the legacy dac. Seems like it would be safer to wrap it in case we need to debug something where it shows up.
I'm happy to close without merging if you disagree though.
@jkotasjkotasJun 21, 2026

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I do not think it is reachable currently.
ResolveHelperFrame is only used by VSD_ResolveWorkerForInterfaceLookupSlot. VSD_ResolveWorkerForInterfaceLookupSlot is only called by JIT_InterfaceLookupForSlot. JIT_InterfaceLookupForSlot ID is CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT.CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT is never emitted by the JIT currently.
I think you can delete this whole chain if you would like.
@leculverleculverJun 21, 2026

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Thanks! I'll close this one and open a new one to do exactly that.
| `StubDispatchFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `StubDispatchFrame` | `RepresentativeMTPtr` | Pointer to Frame's method table pointer |
| `StubDispatchFrame` | `RepresentativeSlot` | Frame's method table slot |
Expand DownExpand Up@@ -401,6 +402,9 @@ The following Frame types also use this mechanism:
* CallCountingHelperFrame
* ExternalMethodFrame
* DynamicHelperFrame
* ResolveHelperFrame

`ResolveHelperFrame` additionally restores the argument registers stored in the `TransitionBlock` on all platforms (not just ARM), because the virtual stub dispatch resolve helper relies on the original argument registers to perform dispatch resolution. This mirrors native `ResolveHelperFrame::UpdateRegDisplay`. It is only present when the runtime is built with `FEATURE_RESOLVE_HELPER_DISPATCH`; when the feature is absent its type descriptor and Frame identifier are not emitted, so no Frame is ever classified as a `ResolveHelperFrame`.

#### FuncEvalFrame

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7 changes: 7 additions & 0 deletions
src/coreclr/vm/datadescriptor/datadescriptor.inc

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Expand Up@@ -1098,6 +1098,13 @@ CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, TransitionBlockPtr, cdac_data<Fram
CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, MethodDescPtr, cdac_data<FramedMethodFrame>::MethodDescPtr)
CDAC_TYPE_END(FramedMethodFrame)

#ifdef FEATURE_RESOLVE_HELPER_DISPATCH
CDAC_TYPE_BEGIN(ResolveHelperFrame)
CDAC_TYPE_SIZE(sizeof(ResolveHelperFrame))
CDAC_TYPE_FIELD(ResolveHelperFrame, T_POINTER, TransitionBlockPtr, cdac_data<ResolveHelperFrame>::TransitionBlockPtr)
CDAC_TYPE_END(ResolveHelperFrame)
#endif // FEATURE_RESOLVE_HELPER_DISPATCH

#ifdef FEATURE_INTERPRETER
CDAC_TYPE_BEGIN(InterpreterFrame)
CDAC_TYPE_INDETERMINATE(InterpreterFrame)
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8 changes: 8 additions & 0 deletions
src/coreclr/vm/frames.h

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Expand Up@@ -951,6 +951,14 @@ class ResolveHelperFrame : public TransitionFrame
 }

 void UpdateRegDisplay_Impl(const PREGDISPLAY, bool updateFloats = false);

 friend struct cdac_data<ResolveHelperFrame>;
};

template<>
struct cdac_data<ResolveHelperFrame>
{
 static constexpr size_t TransitionBlockPtr = offsetof(ResolveHelperFrame, m_pTransitionBlock);
};

#endif // FEATURE_RESOLVE_HELPER_DISPATCH
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6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/AMD64FrameHandler.cs

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Expand Up@@ -58,4 +58,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
}

6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARM64FrameHandler.cs

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Expand Up@@ -48,4 +48,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
Comment thread
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}

7 changes: 5 additions & 2 deletions
...nostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARMFrameHandler.cs

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Expand Up@@ -46,11 +46,14 @@ public override void HandleInlinedCallFrame(InlinedCallFrame inlinedCallFrame)
 }

 public override void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public override void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 // Call the base method to handle common logic
 base.HandleTransitionFrame(framedMethodFrame);
 base.HandleTransitionBlock(transitionBlockPtr);

 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);

 // On ARM, TransitionFrames update the argument registers
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
Expand Down

17 changes: 15 additions & 2 deletions
...ostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/BaseFrameHandler.cs

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Expand Up@@ -42,20 +42,33 @@ public virtual void HandleSoftwareExceptionFrame(SoftwareExceptionFrame software
 }

 public virtual void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public virtual void HandleResolveHelperFrame(ResolveHelperFrame frame)
 => HandleTransitionBlock(frame.TransitionBlockPtr);

 public virtual void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 if (_target.GetTypeInfo(DataType.TransitionBlock).Size is not uint transitionBlockSize)
 {
 throw new InvalidOperationException("TransitionBlock size is not set");
 }

 _context.InstructionPointer = transitionBlock.ReturnAddress;
 _context.StackPointer = framedMethodFrame.TransitionBlockPtr + transitionBlockSize;
 _context.StackPointer = transitionBlockPtr + transitionBlockSize;

 Data.CalleeSavedRegisters calleeSavedRegisters = _target.ProcessedData.GetOrAdd<Data.CalleeSavedRegisters>(transitionBlock.CalleeSavedRegisters);
 UpdateFromRegisterDict(calleeSavedRegisters.Registers);
 }

 protected void UpdateArgumentRegisters(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
 UpdateFromRegisterDict(argumentRegisters.Registers);
 }

 public virtual void HandleFuncEvalFrame(FuncEvalFrame funcEvalFrame)
 {
 Data.DebuggerEval debuggerEval = _target.ProcessedData.GetOrAdd<Data.DebuggerEval>(funcEvalFrame.DebuggerEvalPtr);
Expand Down

22 changes: 19 additions & 3 deletions
...iagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/FrameHelpers.cs

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Expand Up@@ -24,6 +24,7 @@ internal enum FrameType
 ExternalMethodFrame,
 DynamicHelperFrame,
 InterpreterFrame,
 ResolveHelperFrame,

 FuncEvalFrame,

Expand DownExpand Up@@ -141,7 +142,8 @@ public TargetPointer GetMethodDescPtr(TargetPointer framePtr)
 /// </summary>
 public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext context)
 {
 switch (GetFrameType(frame.Identifier))
 FrameType frameType = GetFrameType(frame.Identifier);
 switch (frameType)
 {
 case FrameType.InlinedCallFrame:
 Data.InlinedCallFrame inlinedCallFrame = _target.ProcessedData.GetOrAdd<Data.InlinedCallFrame>(frame.Address);
Expand All@@ -166,6 +168,11 @@ public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext co
 GetFrameHandler(context).HandleTransitionFrame(framedMethodFrame);
 return;

 case FrameType.ResolveHelperFrame:
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 GetFrameHandler(context).HandleResolveHelperFrame(resolveHelperFrame);
 return;

 case FrameType.InterpreterFrame:
 {
 // Mirrors native InterpreterFrame::SetContextToInterpMethodContextFrame
Expand DownExpand Up@@ -232,9 +239,18 @@ public TargetPointer GetReturnAddress(Data.Frame frame)
 case FrameType.CallCountingHelperFrame:
 case FrameType.ExternalMethodFrame:
 case FrameType.DynamicHelperFrame:
 Data.FramedMethodFrame fmf = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(fmf.TransitionBlockPtr);
 {
 Data.FramedMethodFrame framedMethodFrame = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 case FrameType.ResolveHelperFrame:
 {
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(resolveHelperFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 // SoftwareExceptionFrame: stored m_ReturnAddress
 case FrameType.SoftwareExceptionFrame:
Expand Down

2 changes: 2 additions & 0 deletions
...s.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/IPlatformFrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ internal interface IPlatformFrameHandler
 void HandleInlinedCallFrame(Data.InlinedCallFrame frame);
 void HandleSoftwareExceptionFrame(Data.SoftwareExceptionFrame frame);
 void HandleTransitionFrame(Data.FramedMethodFrame frame);
 void HandleTransitionBlock(TargetPointer transitionBlockPtr);
 void HandleResolveHelperFrame(Data.ResolveHelperFrame frame);
 void HandleFuncEvalFrame(Data.FuncEvalFrame frame);
 void HandleResumableFrame(Data.ResumableFrame frame);
 void HandleFaultingExceptionFrame(Data.FaultingExceptionFrame frame);
Expand Down

3 changes: 2 additions & 1 deletion
...dac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/StackWalk_1.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -77,7 +77,8 @@ public bool IsCurrentFrameResumable()
 // HijackFrame should be conditioned on the target architecture.
 return ft is FrameType.ResumableFrame
 or FrameType.RedirectedThreadFrame
 or FrameType.HijackFrame;
 or FrameType.HijackFrame
 or FrameType.ResolveHelperFrame;
 }

 /// <summary>
Expand Down

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...cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/ResolveHelperFrame.cs

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@@ -0,0 +1,10 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

namespace Microsoft.Diagnostics.DataContractReader.Data;

[CdacType(nameof(DataType.ResolveHelperFrame))]
internal partial class ResolveHelperFrame : IData<ResolveHelperFrame>
{
 [Field] public TargetPointer TransitionBlockPtr { get; }
}

1 change: 1 addition & 0 deletions
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/DataType.cs

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Expand Up@@ -166,6 +166,7 @@ public enum DataType
 InlinedCallFrame,
 SoftwareExceptionFrame,
 FramedMethodFrame,
 ResolveHelperFrame,
Comment thread
leculver marked this conversation as resolved.

 FuncEvalFrame,
 ResumableFrame,
 FaultingExceptionFrame,
Expand Down

2 changes: 1 addition & 1 deletion
src/native/managed/cdac/tests/TestInfrastructure/TestPlaceholderTarget.cs

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Expand Up@@ -546,7 +546,7 @@ public override Target.TypeInfo GetTypeInfo(string typeName)
 public override bool TryGetTypeInfo(string typeName, out Target.TypeInfo info)
 => _typeInfoCache.TryGetValue(typeName, out info);

 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => throw new NotImplementedException();
 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => false;

 public override Target.IDataCache ProcessedData => _dataCache;
 public override ContractRegistry Contracts => _contractRegistry;
Expand Down

103 changes: 102 additions & 1 deletion
src/native/managed/cdac/tests/UnitTests/MockDescriptors/MockDescriptors.Frame.cs

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Expand Up@@ -76,6 +76,22 @@ public ulong MethodDescPtr
 }
}

internal sealed class MockResolveHelperFrame : MockFrame
{
 private const string TransitionBlockPtrFieldName = "TransitionBlockPtr";

 public static Layout<MockResolveHelperFrame> CreateLayout(Layout<MockFrame> baseLayout)
 => new SequentialLayoutBuilder("ResolveHelperFrame", baseLayout.Architecture, baseLayout)
 .AddPointerField(TransitionBlockPtrFieldName)
 .Build<MockResolveHelperFrame>();

 public ulong TransitionBlockPtr
 {
 get => ReadPointerField(TransitionBlockPtrFieldName);
 set => WritePointerField(TransitionBlockPtrFieldName, value);
 }
}

internal sealed class MockFuncEvalFrame : MockFrame
{
 // Mirrors the cDAC FuncEvalFrame data class which only reads DebuggerEvalPtr.
Expand DownExpand Up@@ -142,6 +158,59 @@ public ulong TargetContextPtr
 }
}

internal sealed class MockTransitionBlock : TypedView
{
 private const string ReturnAddressFieldName = "ReturnAddress";
 private const string CalleeSavedRegistersFieldName = "CalleeSavedRegisters";
 private const string ArgumentRegistersFieldName = "ArgumentRegisters";
 private const string FirstGCRefMapSlotFieldName = "FirstGCRefMapSlot";

 public static Layout<MockTransitionBlock> CreateLayout(MockTarget.Architecture architecture, Layout<MockRegisterSet> calleeSavedRegistersLayout, Layout<MockRegisterSet> argumentRegistersLayout)
 => new SequentialLayoutBuilder("TransitionBlock", architecture)
 .AddPointerField(ReturnAddressFieldName)
 .AddField(CalleeSavedRegistersFieldName, calleeSavedRegistersLayout.Size)
 .AddField(ArgumentRegistersFieldName, argumentRegistersLayout.Size)
 .AddPointerField(FirstGCRefMapSlotFieldName)
 .Build<MockTransitionBlock>();

 public ulong ReturnAddress
 {
 get => ReadPointerField(ReturnAddressFieldName);
 set => WritePointerField(ReturnAddressFieldName, value);
 }

 public ulong CalleeSavedRegister
 {
 get => ReadPointerField(CalleeSavedRegistersFieldName);
 set => WritePointerField(CalleeSavedRegistersFieldName, value);
 }

 public ulong ArgumentRegister
 {
 get => ReadPointerField(ArgumentRegistersFieldName);
 set => WritePointerField(ArgumentRegistersFieldName, value);
 }
}

internal sealed class MockRegisterSet : TypedView
{
 public const string CalleeSavedRegisterName = "rbx";
 public const string ArgumentRegisterName = "rcx";
 public const string Arm64CalleeSavedRegisterName = "x19";
 public const string Arm64ArgumentRegisterName = "x0";

 public static Layout<MockRegisterSet> CreateLayout(MockTarget.Architecture architecture, string name)
 => new SequentialLayoutBuilder(name, architecture)
 .AddPointerField(name)
 .Build<MockRegisterSet>();

 public ulong Register
 {
 get => ReadPointerField(Layout.Name);
 set => WritePointerField(Layout.Name, value);
 }
}

/// <summary>
/// Helper for building a Frame chain in the mock target memory. The Frame chain is
/// terminated with the FRAME_TOP sentinel (~0 sized to the target pointer width).
Expand All@@ -168,6 +237,7 @@ internal sealed class MockFrameBuilder
 public const ulong InterpreterFrameIdentifierValue = 0x0001_F009;
 public const ulong HijackFrameIdentifierValue = 0x0001_F00A;
 public const ulong RedirectedThreadFrameIdentifierValue = 0x0001_F00B;
 public const ulong ResolveHelperFrameIdentifierValue = 0x0001_F00C;

 private readonly MockMemorySpace.Builder _builder;
 private readonly MockMemorySpace.BumpAllocator _allocator;
Expand All@@ -177,16 +247,25 @@ internal sealed class MockFrameBuilder
 public Layout<MockFrame> FrameLayout { get; }
 public Layout<MockInlinedCallFrame> InlinedCallFrameLayout { get; }
 public Layout<MockFramedMethodFrame> FramedMethodFrameLayout { get; }
 public Layout<MockResolveHelperFrame> ResolveHelperFrameLayout { get; }
 public Layout<MockFuncEvalFrame> FuncEvalFrameLayout { get; }
 public Layout<MockDebuggerEval> DebuggerEvalLayout { get; }
 public Layout<MockResumableFrame> ResumableFrameLayout { get; }
 public Layout<MockTransitionBlock> TransitionBlockLayout { get; }
 public Layout<MockRegisterSet> CalleeSavedRegistersLayout { get; }
 public Layout<MockRegisterSet> ArgumentRegistersLayout { get; }

 public MockFrameBuilder(MockMemorySpace.Builder builder)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd))
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange)
 public MockFrameBuilder(MockMemorySpace.Builder builder, string calleeSavedRegisterName, string argumentRegisterName)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd), calleeSavedRegisterName, argumentRegisterName)
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange, string? calleeSavedRegisterName = null, string? argumentRegisterName = null)
 {
 _builder = builder;
 _helpers = builder.TargetTestHelpers;
Expand All@@ -196,9 +275,13 @@ public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End
 FrameLayout = MockFrame.CreateLayout(_helpers.Arch);
 InlinedCallFrameLayout = MockInlinedCallFrame.CreateLayout(FrameLayout);
 FramedMethodFrameLayout = MockFramedMethodFrame.CreateLayout(FrameLayout);
 ResolveHelperFrameLayout = MockResolveHelperFrame.CreateLayout(FrameLayout);
 FuncEvalFrameLayout = MockFuncEvalFrame.CreateLayout(FrameLayout);
 DebuggerEvalLayout = MockDebuggerEval.CreateLayout(_helpers.Arch);
 ResumableFrameLayout = MockResumableFrame.CreateLayout(FrameLayout);
 CalleeSavedRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, calleeSavedRegisterName ?? MockRegisterSet.CalleeSavedRegisterName);
 ArgumentRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, argumentRegisterName ?? MockRegisterSet.ArgumentRegisterName);
 TransitionBlockLayout = MockTransitionBlock.CreateLayout(_helpers.Arch, CalleeSavedRegistersLayout, ArgumentRegistersLayout);
 }

 public ulong FrameTopTerminator => _terminator;
Expand DownExpand Up@@ -239,6 +322,24 @@ public MockFramedMethodFrame AddFramedMethodFrame(ulong methodDescPtr)
 return frame;
 }

 public MockResolveHelperFrame AddResolveHelperFrame(ulong transitionBlockPtr)
 {
 MockResolveHelperFrame frame = ResolveHelperFrameLayout.Create(_allocator.Allocate((ulong)ResolveHelperFrameLayout.Size, "ResolveHelperFrame"));
 frame.Identifier = ResolveHelperFrameIdentifierValue;
 frame.Next = _terminator;
 frame.TransitionBlockPtr = transitionBlockPtr;
 return frame;
 }

 public MockTransitionBlock AddTransitionBlock(ulong returnAddress, ulong calleeSavedRegister, ulong argumentRegister)
 {
 MockTransitionBlock transitionBlock = TransitionBlockLayout.Create(_allocator.Allocate((ulong)TransitionBlockLayout.Size, "TransitionBlock"));
 transitionBlock.ReturnAddress = returnAddress;
 transitionBlock.CalleeSavedRegister = calleeSavedRegister;
 transitionBlock.ArgumentRegister = argumentRegister;
 return transitionBlock;
 }

 public MockResumableFrame AddRedirectedThreadFrame(ulong targetContextPtr)
 {
 MockResumableFrame frame = ResumableFrameLayout.Create(_allocator.Allocate((ulong)ResumableFrameLayout.Size, "RedirectedThreadFrame"));
Expand Down
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Add cDac contract for ResolveFrameHelper by leculver · Pull Request #129261 · dotnet/runtime · GitHub
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Add cDac contract for ResolveFrameHelper
#129261
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0d9f706

Implement cDAC ResolveHelperFrame handling


leculver Jun 8, 2026
9f19732

Fix cDAC ResolveHelperFrame tests


leculver Jun 10, 2026
b6c8c7a

Separate ResolveHelperFrame return address handling


leculver Jun 10, 2026
3d2fcc9

Document ResolveHelperFrame in StackWalk data contract


leculver Jun 11, 2026
2a8047e

Add ARM64 coverage for ResolveHelperFrame context handling


leculver Jun 11, 2026

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4 changes: 4 additions & 0 deletions
docs/design/datacontracts/StackWalk.md

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Expand Up@@ -103,6 +103,7 @@ This contract depends on the following descriptors:
| `SoftwareExceptionFrame` | `ReturnAddress` | Return address saved in Frame |
| `FramedMethodFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock |
| `FramedMethodFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `ResolveHelperFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock (only present when `FEATURE_RESOLVE_HELPER_DISPATCH` is defined) |
@jkotasjkotasJun 18, 2026

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This was test-only code for Native AOT. I do not think it is currently reachable.
Are you able to actually hit this in tests?
@leculverleculverJun 18, 2026•

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No, this is from code review only. I mostly want to make sure that we aren't missing a cDac contract for some scenario which would require servicing later. This seems to be the only coreclr!Frame that isn't wrapped. If this is pure test code that will never ship, I will close this PR. That wasn't obvious from source inspection.
@leculverleculverJun 18, 2026

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Scanning through it looks like DOTNET_JitForceControlFlowGuard=1 can still reach this, and this code is dac-ized in the legacy dac. Seems like it would be safer to wrap it in case we need to debug something where it shows up.
I'm happy to close without merging if you disagree though.
@jkotasjkotasJun 21, 2026

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I do not think it is reachable currently.
ResolveHelperFrame is only used by VSD_ResolveWorkerForInterfaceLookupSlot. VSD_ResolveWorkerForInterfaceLookupSlot is only called by JIT_InterfaceLookupForSlot. JIT_InterfaceLookupForSlot ID is CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT.CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT is never emitted by the JIT currently.
I think you can delete this whole chain if you would like.
@leculverleculverJun 21, 2026

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Thanks! I'll close this one and open a new one to do exactly that.
| `StubDispatchFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `StubDispatchFrame` | `RepresentativeMTPtr` | Pointer to Frame's method table pointer |
| `StubDispatchFrame` | `RepresentativeSlot` | Frame's method table slot |
Expand DownExpand Up@@ -401,6 +402,9 @@ The following Frame types also use this mechanism:
* CallCountingHelperFrame
* ExternalMethodFrame
* DynamicHelperFrame
* ResolveHelperFrame

`ResolveHelperFrame` additionally restores the argument registers stored in the `TransitionBlock` on all platforms (not just ARM), because the virtual stub dispatch resolve helper relies on the original argument registers to perform dispatch resolution. This mirrors native `ResolveHelperFrame::UpdateRegDisplay`. It is only present when the runtime is built with `FEATURE_RESOLVE_HELPER_DISPATCH`; when the feature is absent its type descriptor and Frame identifier are not emitted, so no Frame is ever classified as a `ResolveHelperFrame`.

#### FuncEvalFrame

Expand Down

7 changes: 7 additions & 0 deletions
src/coreclr/vm/datadescriptor/datadescriptor.inc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1098,6 +1098,13 @@ CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, TransitionBlockPtr, cdac_data<Fram
CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, MethodDescPtr, cdac_data<FramedMethodFrame>::MethodDescPtr)
CDAC_TYPE_END(FramedMethodFrame)

#ifdef FEATURE_RESOLVE_HELPER_DISPATCH
CDAC_TYPE_BEGIN(ResolveHelperFrame)
CDAC_TYPE_SIZE(sizeof(ResolveHelperFrame))
CDAC_TYPE_FIELD(ResolveHelperFrame, T_POINTER, TransitionBlockPtr, cdac_data<ResolveHelperFrame>::TransitionBlockPtr)
CDAC_TYPE_END(ResolveHelperFrame)
#endif // FEATURE_RESOLVE_HELPER_DISPATCH

#ifdef FEATURE_INTERPRETER
CDAC_TYPE_BEGIN(InterpreterFrame)
CDAC_TYPE_INDETERMINATE(InterpreterFrame)
Expand Down

8 changes: 8 additions & 0 deletions
src/coreclr/vm/frames.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -951,6 +951,14 @@ class ResolveHelperFrame : public TransitionFrame
 }

 void UpdateRegDisplay_Impl(const PREGDISPLAY, bool updateFloats = false);

 friend struct cdac_data<ResolveHelperFrame>;
};

template<>
struct cdac_data<ResolveHelperFrame>
{
 static constexpr size_t TransitionBlockPtr = offsetof(ResolveHelperFrame, m_pTransitionBlock);
};

#endif // FEATURE_RESOLVE_HELPER_DISPATCH
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6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/AMD64FrameHandler.cs

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Expand Up@@ -58,4 +58,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
}

6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARM64FrameHandler.cs

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Expand Up@@ -48,4 +48,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
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}

7 changes: 5 additions & 2 deletions
...nostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARMFrameHandler.cs

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Expand Up@@ -46,11 +46,14 @@ public override void HandleInlinedCallFrame(InlinedCallFrame inlinedCallFrame)
 }

 public override void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public override void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 // Call the base method to handle common logic
 base.HandleTransitionFrame(framedMethodFrame);
 base.HandleTransitionBlock(transitionBlockPtr);

 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);

 // On ARM, TransitionFrames update the argument registers
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
Expand Down

17 changes: 15 additions & 2 deletions
...ostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/BaseFrameHandler.cs

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Expand Up@@ -42,20 +42,33 @@ public virtual void HandleSoftwareExceptionFrame(SoftwareExceptionFrame software
 }

 public virtual void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public virtual void HandleResolveHelperFrame(ResolveHelperFrame frame)
 => HandleTransitionBlock(frame.TransitionBlockPtr);

 public virtual void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 if (_target.GetTypeInfo(DataType.TransitionBlock).Size is not uint transitionBlockSize)
 {
 throw new InvalidOperationException("TransitionBlock size is not set");
 }

 _context.InstructionPointer = transitionBlock.ReturnAddress;
 _context.StackPointer = framedMethodFrame.TransitionBlockPtr + transitionBlockSize;
 _context.StackPointer = transitionBlockPtr + transitionBlockSize;

 Data.CalleeSavedRegisters calleeSavedRegisters = _target.ProcessedData.GetOrAdd<Data.CalleeSavedRegisters>(transitionBlock.CalleeSavedRegisters);
 UpdateFromRegisterDict(calleeSavedRegisters.Registers);
 }

 protected void UpdateArgumentRegisters(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
 UpdateFromRegisterDict(argumentRegisters.Registers);
 }

 public virtual void HandleFuncEvalFrame(FuncEvalFrame funcEvalFrame)
 {
 Data.DebuggerEval debuggerEval = _target.ProcessedData.GetOrAdd<Data.DebuggerEval>(funcEvalFrame.DebuggerEvalPtr);
Expand Down

22 changes: 19 additions & 3 deletions
...iagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/FrameHelpers.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -24,6 +24,7 @@ internal enum FrameType
 ExternalMethodFrame,
 DynamicHelperFrame,
 InterpreterFrame,
 ResolveHelperFrame,

 FuncEvalFrame,

Expand DownExpand Up@@ -141,7 +142,8 @@ public TargetPointer GetMethodDescPtr(TargetPointer framePtr)
 /// </summary>
 public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext context)
 {
 switch (GetFrameType(frame.Identifier))
 FrameType frameType = GetFrameType(frame.Identifier);
 switch (frameType)
 {
 case FrameType.InlinedCallFrame:
 Data.InlinedCallFrame inlinedCallFrame = _target.ProcessedData.GetOrAdd<Data.InlinedCallFrame>(frame.Address);
Expand All@@ -166,6 +168,11 @@ public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext co
 GetFrameHandler(context).HandleTransitionFrame(framedMethodFrame);
 return;

 case FrameType.ResolveHelperFrame:
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 GetFrameHandler(context).HandleResolveHelperFrame(resolveHelperFrame);
 return;

 case FrameType.InterpreterFrame:
 {
 // Mirrors native InterpreterFrame::SetContextToInterpMethodContextFrame
Expand DownExpand Up@@ -232,9 +239,18 @@ public TargetPointer GetReturnAddress(Data.Frame frame)
 case FrameType.CallCountingHelperFrame:
 case FrameType.ExternalMethodFrame:
 case FrameType.DynamicHelperFrame:
 Data.FramedMethodFrame fmf = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(fmf.TransitionBlockPtr);
 {
 Data.FramedMethodFrame framedMethodFrame = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 case FrameType.ResolveHelperFrame:
 {
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(resolveHelperFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 // SoftwareExceptionFrame: stored m_ReturnAddress
 case FrameType.SoftwareExceptionFrame:
Expand Down

2 changes: 2 additions & 0 deletions
...s.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/IPlatformFrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ internal interface IPlatformFrameHandler
 void HandleInlinedCallFrame(Data.InlinedCallFrame frame);
 void HandleSoftwareExceptionFrame(Data.SoftwareExceptionFrame frame);
 void HandleTransitionFrame(Data.FramedMethodFrame frame);
 void HandleTransitionBlock(TargetPointer transitionBlockPtr);
 void HandleResolveHelperFrame(Data.ResolveHelperFrame frame);
 void HandleFuncEvalFrame(Data.FuncEvalFrame frame);
 void HandleResumableFrame(Data.ResumableFrame frame);
 void HandleFaultingExceptionFrame(Data.FaultingExceptionFrame frame);
Expand Down

3 changes: 2 additions & 1 deletion
...dac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/StackWalk_1.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -77,7 +77,8 @@ public bool IsCurrentFrameResumable()
 // HijackFrame should be conditioned on the target architecture.
 return ft is FrameType.ResumableFrame
 or FrameType.RedirectedThreadFrame
 or FrameType.HijackFrame;
 or FrameType.HijackFrame
 or FrameType.ResolveHelperFrame;
 }

 /// <summary>
Expand Down

10 changes: 10 additions & 0 deletions
...cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/ResolveHelperFrame.cs

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,10 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

namespace Microsoft.Diagnostics.DataContractReader.Data;

[CdacType(nameof(DataType.ResolveHelperFrame))]
internal partial class ResolveHelperFrame : IData<ResolveHelperFrame>
{
 [Field] public TargetPointer TransitionBlockPtr { get; }
}

1 change: 1 addition & 0 deletions
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/DataType.cs

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Expand Up@@ -166,6 +166,7 @@ public enum DataType
 InlinedCallFrame,
 SoftwareExceptionFrame,
 FramedMethodFrame,
 ResolveHelperFrame,
Comment thread
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 FuncEvalFrame,
 ResumableFrame,
 FaultingExceptionFrame,
Expand Down

2 changes: 1 addition & 1 deletion
src/native/managed/cdac/tests/TestInfrastructure/TestPlaceholderTarget.cs

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Expand Up@@ -546,7 +546,7 @@ public override Target.TypeInfo GetTypeInfo(string typeName)
 public override bool TryGetTypeInfo(string typeName, out Target.TypeInfo info)
 => _typeInfoCache.TryGetValue(typeName, out info);

 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => throw new NotImplementedException();
 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => false;

 public override Target.IDataCache ProcessedData => _dataCache;
 public override ContractRegistry Contracts => _contractRegistry;
Expand Down

103 changes: 102 additions & 1 deletion
src/native/managed/cdac/tests/UnitTests/MockDescriptors/MockDescriptors.Frame.cs

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Expand Up@@ -76,6 +76,22 @@ public ulong MethodDescPtr
 }
}

internal sealed class MockResolveHelperFrame : MockFrame
{
 private const string TransitionBlockPtrFieldName = "TransitionBlockPtr";

 public static Layout<MockResolveHelperFrame> CreateLayout(Layout<MockFrame> baseLayout)
 => new SequentialLayoutBuilder("ResolveHelperFrame", baseLayout.Architecture, baseLayout)
 .AddPointerField(TransitionBlockPtrFieldName)
 .Build<MockResolveHelperFrame>();

 public ulong TransitionBlockPtr
 {
 get => ReadPointerField(TransitionBlockPtrFieldName);
 set => WritePointerField(TransitionBlockPtrFieldName, value);
 }
}

internal sealed class MockFuncEvalFrame : MockFrame
{
 // Mirrors the cDAC FuncEvalFrame data class which only reads DebuggerEvalPtr.
Expand DownExpand Up@@ -142,6 +158,59 @@ public ulong TargetContextPtr
 }
}

internal sealed class MockTransitionBlock : TypedView
{
 private const string ReturnAddressFieldName = "ReturnAddress";
 private const string CalleeSavedRegistersFieldName = "CalleeSavedRegisters";
 private const string ArgumentRegistersFieldName = "ArgumentRegisters";
 private const string FirstGCRefMapSlotFieldName = "FirstGCRefMapSlot";

 public static Layout<MockTransitionBlock> CreateLayout(MockTarget.Architecture architecture, Layout<MockRegisterSet> calleeSavedRegistersLayout, Layout<MockRegisterSet> argumentRegistersLayout)
 => new SequentialLayoutBuilder("TransitionBlock", architecture)
 .AddPointerField(ReturnAddressFieldName)
 .AddField(CalleeSavedRegistersFieldName, calleeSavedRegistersLayout.Size)
 .AddField(ArgumentRegistersFieldName, argumentRegistersLayout.Size)
 .AddPointerField(FirstGCRefMapSlotFieldName)
 .Build<MockTransitionBlock>();

 public ulong ReturnAddress
 {
 get => ReadPointerField(ReturnAddressFieldName);
 set => WritePointerField(ReturnAddressFieldName, value);
 }

 public ulong CalleeSavedRegister
 {
 get => ReadPointerField(CalleeSavedRegistersFieldName);
 set => WritePointerField(CalleeSavedRegistersFieldName, value);
 }

 public ulong ArgumentRegister
 {
 get => ReadPointerField(ArgumentRegistersFieldName);
 set => WritePointerField(ArgumentRegistersFieldName, value);
 }
}

internal sealed class MockRegisterSet : TypedView
{
 public const string CalleeSavedRegisterName = "rbx";
 public const string ArgumentRegisterName = "rcx";
 public const string Arm64CalleeSavedRegisterName = "x19";
 public const string Arm64ArgumentRegisterName = "x0";

 public static Layout<MockRegisterSet> CreateLayout(MockTarget.Architecture architecture, string name)
 => new SequentialLayoutBuilder(name, architecture)
 .AddPointerField(name)
 .Build<MockRegisterSet>();

 public ulong Register
 {
 get => ReadPointerField(Layout.Name);
 set => WritePointerField(Layout.Name, value);
 }
}

/// <summary>
/// Helper for building a Frame chain in the mock target memory. The Frame chain is
/// terminated with the FRAME_TOP sentinel (~0 sized to the target pointer width).
Expand All@@ -168,6 +237,7 @@ internal sealed class MockFrameBuilder
 public const ulong InterpreterFrameIdentifierValue = 0x0001_F009;
 public const ulong HijackFrameIdentifierValue = 0x0001_F00A;
 public const ulong RedirectedThreadFrameIdentifierValue = 0x0001_F00B;
 public const ulong ResolveHelperFrameIdentifierValue = 0x0001_F00C;

 private readonly MockMemorySpace.Builder _builder;
 private readonly MockMemorySpace.BumpAllocator _allocator;
Expand All@@ -177,16 +247,25 @@ internal sealed class MockFrameBuilder
 public Layout<MockFrame> FrameLayout { get; }
 public Layout<MockInlinedCallFrame> InlinedCallFrameLayout { get; }
 public Layout<MockFramedMethodFrame> FramedMethodFrameLayout { get; }
 public Layout<MockResolveHelperFrame> ResolveHelperFrameLayout { get; }
 public Layout<MockFuncEvalFrame> FuncEvalFrameLayout { get; }
 public Layout<MockDebuggerEval> DebuggerEvalLayout { get; }
 public Layout<MockResumableFrame> ResumableFrameLayout { get; }
 public Layout<MockTransitionBlock> TransitionBlockLayout { get; }
 public Layout<MockRegisterSet> CalleeSavedRegistersLayout { get; }
 public Layout<MockRegisterSet> ArgumentRegistersLayout { get; }

 public MockFrameBuilder(MockMemorySpace.Builder builder)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd))
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange)
 public MockFrameBuilder(MockMemorySpace.Builder builder, string calleeSavedRegisterName, string argumentRegisterName)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd), calleeSavedRegisterName, argumentRegisterName)
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange, string? calleeSavedRegisterName = null, string? argumentRegisterName = null)
 {
 _builder = builder;
 _helpers = builder.TargetTestHelpers;
Expand All@@ -196,9 +275,13 @@ public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End
 FrameLayout = MockFrame.CreateLayout(_helpers.Arch);
 InlinedCallFrameLayout = MockInlinedCallFrame.CreateLayout(FrameLayout);
 FramedMethodFrameLayout = MockFramedMethodFrame.CreateLayout(FrameLayout);
 ResolveHelperFrameLayout = MockResolveHelperFrame.CreateLayout(FrameLayout);
 FuncEvalFrameLayout = MockFuncEvalFrame.CreateLayout(FrameLayout);
 DebuggerEvalLayout = MockDebuggerEval.CreateLayout(_helpers.Arch);
 ResumableFrameLayout = MockResumableFrame.CreateLayout(FrameLayout);
 CalleeSavedRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, calleeSavedRegisterName ?? MockRegisterSet.CalleeSavedRegisterName);
 ArgumentRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, argumentRegisterName ?? MockRegisterSet.ArgumentRegisterName);
 TransitionBlockLayout = MockTransitionBlock.CreateLayout(_helpers.Arch, CalleeSavedRegistersLayout, ArgumentRegistersLayout);
 }

 public ulong FrameTopTerminator => _terminator;
Expand DownExpand Up@@ -239,6 +322,24 @@ public MockFramedMethodFrame AddFramedMethodFrame(ulong methodDescPtr)
 return frame;
 }

 public MockResolveHelperFrame AddResolveHelperFrame(ulong transitionBlockPtr)
 {
 MockResolveHelperFrame frame = ResolveHelperFrameLayout.Create(_allocator.Allocate((ulong)ResolveHelperFrameLayout.Size, "ResolveHelperFrame"));
 frame.Identifier = ResolveHelperFrameIdentifierValue;
 frame.Next = _terminator;
 frame.TransitionBlockPtr = transitionBlockPtr;
 return frame;
 }

 public MockTransitionBlock AddTransitionBlock(ulong returnAddress, ulong calleeSavedRegister, ulong argumentRegister)
 {
 MockTransitionBlock transitionBlock = TransitionBlockLayout.Create(_allocator.Allocate((ulong)TransitionBlockLayout.Size, "TransitionBlock"));
 transitionBlock.ReturnAddress = returnAddress;
 transitionBlock.CalleeSavedRegister = calleeSavedRegister;
 transitionBlock.ArgumentRegister = argumentRegister;
 return transitionBlock;
 }

 public MockResumableFrame AddRedirectedThreadFrame(ulong targetContextPtr)
 {
 MockResumableFrame frame = ResumableFrameLayout.Create(_allocator.Allocate((ulong)ResumableFrameLayout.Size, "RedirectedThreadFrame"));
Expand Down
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Add cDac contract for ResolveFrameHelper by leculver · Pull Request #129261 · dotnet/runtime · GitHub
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Add cDac contract for ResolveFrameHelper
#129261
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0d9f706

Implement cDAC ResolveHelperFrame handling


leculver Jun 8, 2026
9f19732

Fix cDAC ResolveHelperFrame tests


leculver Jun 10, 2026
b6c8c7a

Separate ResolveHelperFrame return address handling


leculver Jun 10, 2026
3d2fcc9

Document ResolveHelperFrame in StackWalk data contract


leculver Jun 11, 2026
2a8047e

Add ARM64 coverage for ResolveHelperFrame context handling


leculver Jun 11, 2026

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4 changes: 4 additions & 0 deletions
docs/design/datacontracts/StackWalk.md

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Expand Up@@ -103,6 +103,7 @@ This contract depends on the following descriptors:
| `SoftwareExceptionFrame` | `ReturnAddress` | Return address saved in Frame |
| `FramedMethodFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock |
| `FramedMethodFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `ResolveHelperFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock (only present when `FEATURE_RESOLVE_HELPER_DISPATCH` is defined) |
@jkotasjkotasJun 18, 2026

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This was test-only code for Native AOT. I do not think it is currently reachable.
Are you able to actually hit this in tests?
@leculverleculverJun 18, 2026•

edited

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No, this is from code review only. I mostly want to make sure that we aren't missing a cDac contract for some scenario which would require servicing later. This seems to be the only coreclr!Frame that isn't wrapped. If this is pure test code that will never ship, I will close this PR. That wasn't obvious from source inspection.
@leculverleculverJun 18, 2026

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Scanning through it looks like DOTNET_JitForceControlFlowGuard=1 can still reach this, and this code is dac-ized in the legacy dac. Seems like it would be safer to wrap it in case we need to debug something where it shows up.
I'm happy to close without merging if you disagree though.
@jkotasjkotasJun 21, 2026

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I do not think it is reachable currently.
ResolveHelperFrame is only used by VSD_ResolveWorkerForInterfaceLookupSlot. VSD_ResolveWorkerForInterfaceLookupSlot is only called by JIT_InterfaceLookupForSlot. JIT_InterfaceLookupForSlot ID is CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT.CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT is never emitted by the JIT currently.
I think you can delete this whole chain if you would like.
@leculverleculverJun 21, 2026

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Thanks! I'll close this one and open a new one to do exactly that.
| `StubDispatchFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `StubDispatchFrame` | `RepresentativeMTPtr` | Pointer to Frame's method table pointer |
| `StubDispatchFrame` | `RepresentativeSlot` | Frame's method table slot |
Expand DownExpand Up@@ -401,6 +402,9 @@ The following Frame types also use this mechanism:
* CallCountingHelperFrame
* ExternalMethodFrame
* DynamicHelperFrame
* ResolveHelperFrame

`ResolveHelperFrame` additionally restores the argument registers stored in the `TransitionBlock` on all platforms (not just ARM), because the virtual stub dispatch resolve helper relies on the original argument registers to perform dispatch resolution. This mirrors native `ResolveHelperFrame::UpdateRegDisplay`. It is only present when the runtime is built with `FEATURE_RESOLVE_HELPER_DISPATCH`; when the feature is absent its type descriptor and Frame identifier are not emitted, so no Frame is ever classified as a `ResolveHelperFrame`.

#### FuncEvalFrame

Expand Down

7 changes: 7 additions & 0 deletions
src/coreclr/vm/datadescriptor/datadescriptor.inc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1098,6 +1098,13 @@ CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, TransitionBlockPtr, cdac_data<Fram
CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, MethodDescPtr, cdac_data<FramedMethodFrame>::MethodDescPtr)
CDAC_TYPE_END(FramedMethodFrame)

#ifdef FEATURE_RESOLVE_HELPER_DISPATCH
CDAC_TYPE_BEGIN(ResolveHelperFrame)
CDAC_TYPE_SIZE(sizeof(ResolveHelperFrame))
CDAC_TYPE_FIELD(ResolveHelperFrame, T_POINTER, TransitionBlockPtr, cdac_data<ResolveHelperFrame>::TransitionBlockPtr)
CDAC_TYPE_END(ResolveHelperFrame)
#endif // FEATURE_RESOLVE_HELPER_DISPATCH

#ifdef FEATURE_INTERPRETER
CDAC_TYPE_BEGIN(InterpreterFrame)
CDAC_TYPE_INDETERMINATE(InterpreterFrame)
Expand Down

8 changes: 8 additions & 0 deletions
src/coreclr/vm/frames.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -951,6 +951,14 @@ class ResolveHelperFrame : public TransitionFrame
 }

 void UpdateRegDisplay_Impl(const PREGDISPLAY, bool updateFloats = false);

 friend struct cdac_data<ResolveHelperFrame>;
};

template<>
struct cdac_data<ResolveHelperFrame>
{
 static constexpr size_t TransitionBlockPtr = offsetof(ResolveHelperFrame, m_pTransitionBlock);
};

#endif // FEATURE_RESOLVE_HELPER_DISPATCH
Expand Down

6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/AMD64FrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -58,4 +58,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
}

6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARM64FrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -48,4 +48,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
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}

7 changes: 5 additions & 2 deletions
...nostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARMFrameHandler.cs

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Expand Up@@ -46,11 +46,14 @@ public override void HandleInlinedCallFrame(InlinedCallFrame inlinedCallFrame)
 }

 public override void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public override void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 // Call the base method to handle common logic
 base.HandleTransitionFrame(framedMethodFrame);
 base.HandleTransitionBlock(transitionBlockPtr);

 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);

 // On ARM, TransitionFrames update the argument registers
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
Expand Down

17 changes: 15 additions & 2 deletions
...ostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/BaseFrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -42,20 +42,33 @@ public virtual void HandleSoftwareExceptionFrame(SoftwareExceptionFrame software
 }

 public virtual void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public virtual void HandleResolveHelperFrame(ResolveHelperFrame frame)
 => HandleTransitionBlock(frame.TransitionBlockPtr);

 public virtual void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 if (_target.GetTypeInfo(DataType.TransitionBlock).Size is not uint transitionBlockSize)
 {
 throw new InvalidOperationException("TransitionBlock size is not set");
 }

 _context.InstructionPointer = transitionBlock.ReturnAddress;
 _context.StackPointer = framedMethodFrame.TransitionBlockPtr + transitionBlockSize;
 _context.StackPointer = transitionBlockPtr + transitionBlockSize;

 Data.CalleeSavedRegisters calleeSavedRegisters = _target.ProcessedData.GetOrAdd<Data.CalleeSavedRegisters>(transitionBlock.CalleeSavedRegisters);
 UpdateFromRegisterDict(calleeSavedRegisters.Registers);
 }

 protected void UpdateArgumentRegisters(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
 UpdateFromRegisterDict(argumentRegisters.Registers);
 }

 public virtual void HandleFuncEvalFrame(FuncEvalFrame funcEvalFrame)
 {
 Data.DebuggerEval debuggerEval = _target.ProcessedData.GetOrAdd<Data.DebuggerEval>(funcEvalFrame.DebuggerEvalPtr);
Expand Down

22 changes: 19 additions & 3 deletions
...iagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/FrameHelpers.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -24,6 +24,7 @@ internal enum FrameType
 ExternalMethodFrame,
 DynamicHelperFrame,
 InterpreterFrame,
 ResolveHelperFrame,

 FuncEvalFrame,

Expand DownExpand Up@@ -141,7 +142,8 @@ public TargetPointer GetMethodDescPtr(TargetPointer framePtr)
 /// </summary>
 public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext context)
 {
 switch (GetFrameType(frame.Identifier))
 FrameType frameType = GetFrameType(frame.Identifier);
 switch (frameType)
 {
 case FrameType.InlinedCallFrame:
 Data.InlinedCallFrame inlinedCallFrame = _target.ProcessedData.GetOrAdd<Data.InlinedCallFrame>(frame.Address);
Expand All@@ -166,6 +168,11 @@ public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext co
 GetFrameHandler(context).HandleTransitionFrame(framedMethodFrame);
 return;

 case FrameType.ResolveHelperFrame:
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 GetFrameHandler(context).HandleResolveHelperFrame(resolveHelperFrame);
 return;

 case FrameType.InterpreterFrame:
 {
 // Mirrors native InterpreterFrame::SetContextToInterpMethodContextFrame
Expand DownExpand Up@@ -232,9 +239,18 @@ public TargetPointer GetReturnAddress(Data.Frame frame)
 case FrameType.CallCountingHelperFrame:
 case FrameType.ExternalMethodFrame:
 case FrameType.DynamicHelperFrame:
 Data.FramedMethodFrame fmf = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(fmf.TransitionBlockPtr);
 {
 Data.FramedMethodFrame framedMethodFrame = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 case FrameType.ResolveHelperFrame:
 {
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(resolveHelperFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 // SoftwareExceptionFrame: stored m_ReturnAddress
 case FrameType.SoftwareExceptionFrame:
Expand Down

2 changes: 2 additions & 0 deletions
...s.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/IPlatformFrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ internal interface IPlatformFrameHandler
 void HandleInlinedCallFrame(Data.InlinedCallFrame frame);
 void HandleSoftwareExceptionFrame(Data.SoftwareExceptionFrame frame);
 void HandleTransitionFrame(Data.FramedMethodFrame frame);
 void HandleTransitionBlock(TargetPointer transitionBlockPtr);
 void HandleResolveHelperFrame(Data.ResolveHelperFrame frame);
 void HandleFuncEvalFrame(Data.FuncEvalFrame frame);
 void HandleResumableFrame(Data.ResumableFrame frame);
 void HandleFaultingExceptionFrame(Data.FaultingExceptionFrame frame);
Expand Down

3 changes: 2 additions & 1 deletion
...dac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/StackWalk_1.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -77,7 +77,8 @@ public bool IsCurrentFrameResumable()
 // HijackFrame should be conditioned on the target architecture.
 return ft is FrameType.ResumableFrame
 or FrameType.RedirectedThreadFrame
 or FrameType.HijackFrame;
 or FrameType.HijackFrame
 or FrameType.ResolveHelperFrame;
 }

 /// <summary>
Expand Down

10 changes: 10 additions & 0 deletions
...cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/ResolveHelperFrame.cs

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,10 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

namespace Microsoft.Diagnostics.DataContractReader.Data;

[CdacType(nameof(DataType.ResolveHelperFrame))]
internal partial class ResolveHelperFrame : IData<ResolveHelperFrame>
{
 [Field] public TargetPointer TransitionBlockPtr { get; }
}

1 change: 1 addition & 0 deletions
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/DataType.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -166,6 +166,7 @@ public enum DataType
 InlinedCallFrame,
 SoftwareExceptionFrame,
 FramedMethodFrame,
 ResolveHelperFrame,
Comment thread
leculver marked this conversation as resolved.

 FuncEvalFrame,
 ResumableFrame,
 FaultingExceptionFrame,
Expand Down

2 changes: 1 addition & 1 deletion
src/native/managed/cdac/tests/TestInfrastructure/TestPlaceholderTarget.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -546,7 +546,7 @@ public override Target.TypeInfo GetTypeInfo(string typeName)
 public override bool TryGetTypeInfo(string typeName, out Target.TypeInfo info)
 => _typeInfoCache.TryGetValue(typeName, out info);

 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => throw new NotImplementedException();
 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => false;

 public override Target.IDataCache ProcessedData => _dataCache;
 public override ContractRegistry Contracts => _contractRegistry;
Expand Down

103 changes: 102 additions & 1 deletion
src/native/managed/cdac/tests/UnitTests/MockDescriptors/MockDescriptors.Frame.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -76,6 +76,22 @@ public ulong MethodDescPtr
 }
}

internal sealed class MockResolveHelperFrame : MockFrame
{
 private const string TransitionBlockPtrFieldName = "TransitionBlockPtr";

 public static Layout<MockResolveHelperFrame> CreateLayout(Layout<MockFrame> baseLayout)
 => new SequentialLayoutBuilder("ResolveHelperFrame", baseLayout.Architecture, baseLayout)
 .AddPointerField(TransitionBlockPtrFieldName)
 .Build<MockResolveHelperFrame>();

 public ulong TransitionBlockPtr
 {
 get => ReadPointerField(TransitionBlockPtrFieldName);
 set => WritePointerField(TransitionBlockPtrFieldName, value);
 }
}

internal sealed class MockFuncEvalFrame : MockFrame
{
 // Mirrors the cDAC FuncEvalFrame data class which only reads DebuggerEvalPtr.
Expand DownExpand Up@@ -142,6 +158,59 @@ public ulong TargetContextPtr
 }
}

internal sealed class MockTransitionBlock : TypedView
{
 private const string ReturnAddressFieldName = "ReturnAddress";
 private const string CalleeSavedRegistersFieldName = "CalleeSavedRegisters";
 private const string ArgumentRegistersFieldName = "ArgumentRegisters";
 private const string FirstGCRefMapSlotFieldName = "FirstGCRefMapSlot";

 public static Layout<MockTransitionBlock> CreateLayout(MockTarget.Architecture architecture, Layout<MockRegisterSet> calleeSavedRegistersLayout, Layout<MockRegisterSet> argumentRegistersLayout)
 => new SequentialLayoutBuilder("TransitionBlock", architecture)
 .AddPointerField(ReturnAddressFieldName)
 .AddField(CalleeSavedRegistersFieldName, calleeSavedRegistersLayout.Size)
 .AddField(ArgumentRegistersFieldName, argumentRegistersLayout.Size)
 .AddPointerField(FirstGCRefMapSlotFieldName)
 .Build<MockTransitionBlock>();

 public ulong ReturnAddress
 {
 get => ReadPointerField(ReturnAddressFieldName);
 set => WritePointerField(ReturnAddressFieldName, value);
 }

 public ulong CalleeSavedRegister
 {
 get => ReadPointerField(CalleeSavedRegistersFieldName);
 set => WritePointerField(CalleeSavedRegistersFieldName, value);
 }

 public ulong ArgumentRegister
 {
 get => ReadPointerField(ArgumentRegistersFieldName);
 set => WritePointerField(ArgumentRegistersFieldName, value);
 }
}

internal sealed class MockRegisterSet : TypedView
{
 public const string CalleeSavedRegisterName = "rbx";
 public const string ArgumentRegisterName = "rcx";
 public const string Arm64CalleeSavedRegisterName = "x19";
 public const string Arm64ArgumentRegisterName = "x0";

 public static Layout<MockRegisterSet> CreateLayout(MockTarget.Architecture architecture, string name)
 => new SequentialLayoutBuilder(name, architecture)
 .AddPointerField(name)
 .Build<MockRegisterSet>();

 public ulong Register
 {
 get => ReadPointerField(Layout.Name);
 set => WritePointerField(Layout.Name, value);
 }
}

/// <summary>
/// Helper for building a Frame chain in the mock target memory. The Frame chain is
/// terminated with the FRAME_TOP sentinel (~0 sized to the target pointer width).
Expand All@@ -168,6 +237,7 @@ internal sealed class MockFrameBuilder
 public const ulong InterpreterFrameIdentifierValue = 0x0001_F009;
 public const ulong HijackFrameIdentifierValue = 0x0001_F00A;
 public const ulong RedirectedThreadFrameIdentifierValue = 0x0001_F00B;
 public const ulong ResolveHelperFrameIdentifierValue = 0x0001_F00C;

 private readonly MockMemorySpace.Builder _builder;
 private readonly MockMemorySpace.BumpAllocator _allocator;
Expand All@@ -177,16 +247,25 @@ internal sealed class MockFrameBuilder
 public Layout<MockFrame> FrameLayout { get; }
 public Layout<MockInlinedCallFrame> InlinedCallFrameLayout { get; }
 public Layout<MockFramedMethodFrame> FramedMethodFrameLayout { get; }
 public Layout<MockResolveHelperFrame> ResolveHelperFrameLayout { get; }
 public Layout<MockFuncEvalFrame> FuncEvalFrameLayout { get; }
 public Layout<MockDebuggerEval> DebuggerEvalLayout { get; }
 public Layout<MockResumableFrame> ResumableFrameLayout { get; }
 public Layout<MockTransitionBlock> TransitionBlockLayout { get; }
 public Layout<MockRegisterSet> CalleeSavedRegistersLayout { get; }
 public Layout<MockRegisterSet> ArgumentRegistersLayout { get; }

 public MockFrameBuilder(MockMemorySpace.Builder builder)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd))
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange)
 public MockFrameBuilder(MockMemorySpace.Builder builder, string calleeSavedRegisterName, string argumentRegisterName)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd), calleeSavedRegisterName, argumentRegisterName)
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange, string? calleeSavedRegisterName = null, string? argumentRegisterName = null)
 {
 _builder = builder;
 _helpers = builder.TargetTestHelpers;
Expand All@@ -196,9 +275,13 @@ public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End
 FrameLayout = MockFrame.CreateLayout(_helpers.Arch);
 InlinedCallFrameLayout = MockInlinedCallFrame.CreateLayout(FrameLayout);
 FramedMethodFrameLayout = MockFramedMethodFrame.CreateLayout(FrameLayout);
 ResolveHelperFrameLayout = MockResolveHelperFrame.CreateLayout(FrameLayout);
 FuncEvalFrameLayout = MockFuncEvalFrame.CreateLayout(FrameLayout);
 DebuggerEvalLayout = MockDebuggerEval.CreateLayout(_helpers.Arch);
 ResumableFrameLayout = MockResumableFrame.CreateLayout(FrameLayout);
 CalleeSavedRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, calleeSavedRegisterName ?? MockRegisterSet.CalleeSavedRegisterName);
 ArgumentRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, argumentRegisterName ?? MockRegisterSet.ArgumentRegisterName);
 TransitionBlockLayout = MockTransitionBlock.CreateLayout(_helpers.Arch, CalleeSavedRegistersLayout, ArgumentRegistersLayout);
 }

 public ulong FrameTopTerminator => _terminator;
Expand DownExpand Up@@ -239,6 +322,24 @@ public MockFramedMethodFrame AddFramedMethodFrame(ulong methodDescPtr)
 return frame;
 }

 public MockResolveHelperFrame AddResolveHelperFrame(ulong transitionBlockPtr)
 {
 MockResolveHelperFrame frame = ResolveHelperFrameLayout.Create(_allocator.Allocate((ulong)ResolveHelperFrameLayout.Size, "ResolveHelperFrame"));
 frame.Identifier = ResolveHelperFrameIdentifierValue;
 frame.Next = _terminator;
 frame.TransitionBlockPtr = transitionBlockPtr;
 return frame;
 }

 public MockTransitionBlock AddTransitionBlock(ulong returnAddress, ulong calleeSavedRegister, ulong argumentRegister)
 {
 MockTransitionBlock transitionBlock = TransitionBlockLayout.Create(_allocator.Allocate((ulong)TransitionBlockLayout.Size, "TransitionBlock"));
 transitionBlock.ReturnAddress = returnAddress;
 transitionBlock.CalleeSavedRegister = calleeSavedRegister;
 transitionBlock.ArgumentRegister = argumentRegister;
 return transitionBlock;
 }

 public MockResumableFrame AddRedirectedThreadFrame(ulong targetContextPtr)
 {
 MockResumableFrame frame = ResumableFrameLayout.Create(_allocator.Allocate((ulong)ResumableFrameLayout.Size, "RedirectedThreadFrame"));
Expand Down
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Strip utm_, fbclid, gclid, etc. from all links on page
(function() {
var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',
'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',
'ref', 'ref_src', 'source', 'medium', 'campaign'];
function cleanUrl(url) {
try {
var u = new URL(url, window.location.origin);
var changed = false;
trackingParams.forEach(function(p) {
if (u.searchParams.has(p)) {
u.searchParams.delete(p);
changed = true;
}
});
return changed ? u.toString() : url;
} catch (e) {
return url;
}
}
function cleanLinks() {
document.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
cleanLinks();
var observer = new MutationObserver(function(mutations) {
mutations.forEach(function(m) {
m.addedNodes.forEach(function(node) {
if (node.nodeType === 1) {
if (node.tagName === 'A') cleanLinks();
node.querySelectorAll('a[href]').forEach(function(a) {
var clean = cleanUrl(a.href);
if (clean !== a.href) a.href = clean;
});
}
});
});
});
observer.observe(document.body, { childList: true, subtree: true });
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}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '
Add cDac contract for ResolveFrameHelper by leculver · Pull Request #129261 · dotnet/runtime · GitHub
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leculver
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Add cDac contract for ResolveFrameHelper
#129261
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0d9f706

Implement cDAC ResolveHelperFrame handling


leculver Jun 8, 2026
9f19732

Fix cDAC ResolveHelperFrame tests


leculver Jun 10, 2026
b6c8c7a

Separate ResolveHelperFrame return address handling


leculver Jun 10, 2026
3d2fcc9

Document ResolveHelperFrame in StackWalk data contract


leculver Jun 11, 2026
2a8047e

Add ARM64 coverage for ResolveHelperFrame context handling


leculver Jun 11, 2026

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4 changes: 4 additions & 0 deletions
docs/design/datacontracts/StackWalk.md

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Expand Up@@ -103,6 +103,7 @@ This contract depends on the following descriptors:
| `SoftwareExceptionFrame` | `ReturnAddress` | Return address saved in Frame |
| `FramedMethodFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock |
| `FramedMethodFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `ResolveHelperFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock (only present when `FEATURE_RESOLVE_HELPER_DISPATCH` is defined) |
@jkotasjkotasJun 18, 2026

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This was test-only code for Native AOT. I do not think it is currently reachable.
Are you able to actually hit this in tests?
@leculverleculverJun 18, 2026•

edited

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No, this is from code review only. I mostly want to make sure that we aren't missing a cDac contract for some scenario which would require servicing later. This seems to be the only coreclr!Frame that isn't wrapped. If this is pure test code that will never ship, I will close this PR. That wasn't obvious from source inspection.
@leculverleculverJun 18, 2026

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Scanning through it looks like DOTNET_JitForceControlFlowGuard=1 can still reach this, and this code is dac-ized in the legacy dac. Seems like it would be safer to wrap it in case we need to debug something where it shows up.
I'm happy to close without merging if you disagree though.
@jkotasjkotasJun 21, 2026

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I do not think it is reachable currently.
ResolveHelperFrame is only used by VSD_ResolveWorkerForInterfaceLookupSlot. VSD_ResolveWorkerForInterfaceLookupSlot is only called by JIT_InterfaceLookupForSlot. JIT_InterfaceLookupForSlot ID is CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT.CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT is never emitted by the JIT currently.
I think you can delete this whole chain if you would like.
@leculverleculverJun 21, 2026

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Thanks! I'll close this one and open a new one to do exactly that.
| `StubDispatchFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `StubDispatchFrame` | `RepresentativeMTPtr` | Pointer to Frame's method table pointer |
| `StubDispatchFrame` | `RepresentativeSlot` | Frame's method table slot |
Expand DownExpand Up@@ -401,6 +402,9 @@ The following Frame types also use this mechanism:
* CallCountingHelperFrame
* ExternalMethodFrame
* DynamicHelperFrame
* ResolveHelperFrame

`ResolveHelperFrame` additionally restores the argument registers stored in the `TransitionBlock` on all platforms (not just ARM), because the virtual stub dispatch resolve helper relies on the original argument registers to perform dispatch resolution. This mirrors native `ResolveHelperFrame::UpdateRegDisplay`. It is only present when the runtime is built with `FEATURE_RESOLVE_HELPER_DISPATCH`; when the feature is absent its type descriptor and Frame identifier are not emitted, so no Frame is ever classified as a `ResolveHelperFrame`.

#### FuncEvalFrame

Expand Down

7 changes: 7 additions & 0 deletions
src/coreclr/vm/datadescriptor/datadescriptor.inc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1098,6 +1098,13 @@ CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, TransitionBlockPtr, cdac_data<Fram
CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, MethodDescPtr, cdac_data<FramedMethodFrame>::MethodDescPtr)
CDAC_TYPE_END(FramedMethodFrame)

#ifdef FEATURE_RESOLVE_HELPER_DISPATCH
CDAC_TYPE_BEGIN(ResolveHelperFrame)
CDAC_TYPE_SIZE(sizeof(ResolveHelperFrame))
CDAC_TYPE_FIELD(ResolveHelperFrame, T_POINTER, TransitionBlockPtr, cdac_data<ResolveHelperFrame>::TransitionBlockPtr)
CDAC_TYPE_END(ResolveHelperFrame)
#endif // FEATURE_RESOLVE_HELPER_DISPATCH

#ifdef FEATURE_INTERPRETER
CDAC_TYPE_BEGIN(InterpreterFrame)
CDAC_TYPE_INDETERMINATE(InterpreterFrame)
Expand Down

8 changes: 8 additions & 0 deletions
src/coreclr/vm/frames.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -951,6 +951,14 @@ class ResolveHelperFrame : public TransitionFrame
 }

 void UpdateRegDisplay_Impl(const PREGDISPLAY, bool updateFloats = false);

 friend struct cdac_data<ResolveHelperFrame>;
};

template<>
struct cdac_data<ResolveHelperFrame>
{
 static constexpr size_t TransitionBlockPtr = offsetof(ResolveHelperFrame, m_pTransitionBlock);
};

#endif // FEATURE_RESOLVE_HELPER_DISPATCH
Expand Down

6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/AMD64FrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -58,4 +58,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
}

6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARM64FrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -48,4 +48,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
Comment thread
leculver marked this conversation as resolved.

}

7 changes: 5 additions & 2 deletions
...nostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARMFrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -46,11 +46,14 @@ public override void HandleInlinedCallFrame(InlinedCallFrame inlinedCallFrame)
 }

 public override void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public override void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 // Call the base method to handle common logic
 base.HandleTransitionFrame(framedMethodFrame);
 base.HandleTransitionBlock(transitionBlockPtr);

 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);

 // On ARM, TransitionFrames update the argument registers
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
Expand Down

17 changes: 15 additions & 2 deletions
...ostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/BaseFrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -42,20 +42,33 @@ public virtual void HandleSoftwareExceptionFrame(SoftwareExceptionFrame software
 }

 public virtual void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public virtual void HandleResolveHelperFrame(ResolveHelperFrame frame)
 => HandleTransitionBlock(frame.TransitionBlockPtr);

 public virtual void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 if (_target.GetTypeInfo(DataType.TransitionBlock).Size is not uint transitionBlockSize)
 {
 throw new InvalidOperationException("TransitionBlock size is not set");
 }

 _context.InstructionPointer = transitionBlock.ReturnAddress;
 _context.StackPointer = framedMethodFrame.TransitionBlockPtr + transitionBlockSize;
 _context.StackPointer = transitionBlockPtr + transitionBlockSize;

 Data.CalleeSavedRegisters calleeSavedRegisters = _target.ProcessedData.GetOrAdd<Data.CalleeSavedRegisters>(transitionBlock.CalleeSavedRegisters);
 UpdateFromRegisterDict(calleeSavedRegisters.Registers);
 }

 protected void UpdateArgumentRegisters(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
 UpdateFromRegisterDict(argumentRegisters.Registers);
 }

 public virtual void HandleFuncEvalFrame(FuncEvalFrame funcEvalFrame)
 {
 Data.DebuggerEval debuggerEval = _target.ProcessedData.GetOrAdd<Data.DebuggerEval>(funcEvalFrame.DebuggerEvalPtr);
Expand Down

22 changes: 19 additions & 3 deletions
...iagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/FrameHelpers.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -24,6 +24,7 @@ internal enum FrameType
 ExternalMethodFrame,
 DynamicHelperFrame,
 InterpreterFrame,
 ResolveHelperFrame,

 FuncEvalFrame,

Expand DownExpand Up@@ -141,7 +142,8 @@ public TargetPointer GetMethodDescPtr(TargetPointer framePtr)
 /// </summary>
 public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext context)
 {
 switch (GetFrameType(frame.Identifier))
 FrameType frameType = GetFrameType(frame.Identifier);
 switch (frameType)
 {
 case FrameType.InlinedCallFrame:
 Data.InlinedCallFrame inlinedCallFrame = _target.ProcessedData.GetOrAdd<Data.InlinedCallFrame>(frame.Address);
Expand All@@ -166,6 +168,11 @@ public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext co
 GetFrameHandler(context).HandleTransitionFrame(framedMethodFrame);
 return;

 case FrameType.ResolveHelperFrame:
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 GetFrameHandler(context).HandleResolveHelperFrame(resolveHelperFrame);
 return;

 case FrameType.InterpreterFrame:
 {
 // Mirrors native InterpreterFrame::SetContextToInterpMethodContextFrame
Expand DownExpand Up@@ -232,9 +239,18 @@ public TargetPointer GetReturnAddress(Data.Frame frame)
 case FrameType.CallCountingHelperFrame:
 case FrameType.ExternalMethodFrame:
 case FrameType.DynamicHelperFrame:
 Data.FramedMethodFrame fmf = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(fmf.TransitionBlockPtr);
 {
 Data.FramedMethodFrame framedMethodFrame = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 case FrameType.ResolveHelperFrame:
 {
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(resolveHelperFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 // SoftwareExceptionFrame: stored m_ReturnAddress
 case FrameType.SoftwareExceptionFrame:
Expand Down

2 changes: 2 additions & 0 deletions
...s.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/IPlatformFrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ internal interface IPlatformFrameHandler
 void HandleInlinedCallFrame(Data.InlinedCallFrame frame);
 void HandleSoftwareExceptionFrame(Data.SoftwareExceptionFrame frame);
 void HandleTransitionFrame(Data.FramedMethodFrame frame);
 void HandleTransitionBlock(TargetPointer transitionBlockPtr);
 void HandleResolveHelperFrame(Data.ResolveHelperFrame frame);
 void HandleFuncEvalFrame(Data.FuncEvalFrame frame);
 void HandleResumableFrame(Data.ResumableFrame frame);
 void HandleFaultingExceptionFrame(Data.FaultingExceptionFrame frame);
Expand Down

3 changes: 2 additions & 1 deletion
...dac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/StackWalk_1.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -77,7 +77,8 @@ public bool IsCurrentFrameResumable()
 // HijackFrame should be conditioned on the target architecture.
 return ft is FrameType.ResumableFrame
 or FrameType.RedirectedThreadFrame
 or FrameType.HijackFrame;
 or FrameType.HijackFrame
 or FrameType.ResolveHelperFrame;
 }

 /// <summary>
Expand Down

10 changes: 10 additions & 0 deletions
...cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/ResolveHelperFrame.cs

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,10 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

namespace Microsoft.Diagnostics.DataContractReader.Data;

[CdacType(nameof(DataType.ResolveHelperFrame))]
internal partial class ResolveHelperFrame : IData<ResolveHelperFrame>
{
 [Field] public TargetPointer TransitionBlockPtr { get; }
}

1 change: 1 addition & 0 deletions
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/DataType.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -166,6 +166,7 @@ public enum DataType
 InlinedCallFrame,
 SoftwareExceptionFrame,
 FramedMethodFrame,
 ResolveHelperFrame,
Comment thread
leculver marked this conversation as resolved.

 FuncEvalFrame,
 ResumableFrame,
 FaultingExceptionFrame,
Expand Down

2 changes: 1 addition & 1 deletion
src/native/managed/cdac/tests/TestInfrastructure/TestPlaceholderTarget.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -546,7 +546,7 @@ public override Target.TypeInfo GetTypeInfo(string typeName)
 public override bool TryGetTypeInfo(string typeName, out Target.TypeInfo info)
 => _typeInfoCache.TryGetValue(typeName, out info);

 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => throw new NotImplementedException();
 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => false;

 public override Target.IDataCache ProcessedData => _dataCache;
 public override ContractRegistry Contracts => _contractRegistry;
Expand Down

103 changes: 102 additions & 1 deletion
src/native/managed/cdac/tests/UnitTests/MockDescriptors/MockDescriptors.Frame.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -76,6 +76,22 @@ public ulong MethodDescPtr
 }
}

internal sealed class MockResolveHelperFrame : MockFrame
{
 private const string TransitionBlockPtrFieldName = "TransitionBlockPtr";

 public static Layout<MockResolveHelperFrame> CreateLayout(Layout<MockFrame> baseLayout)
 => new SequentialLayoutBuilder("ResolveHelperFrame", baseLayout.Architecture, baseLayout)
 .AddPointerField(TransitionBlockPtrFieldName)
 .Build<MockResolveHelperFrame>();

 public ulong TransitionBlockPtr
 {
 get => ReadPointerField(TransitionBlockPtrFieldName);
 set => WritePointerField(TransitionBlockPtrFieldName, value);
 }
}

internal sealed class MockFuncEvalFrame : MockFrame
{
 // Mirrors the cDAC FuncEvalFrame data class which only reads DebuggerEvalPtr.
Expand DownExpand Up@@ -142,6 +158,59 @@ public ulong TargetContextPtr
 }
}

internal sealed class MockTransitionBlock : TypedView
{
 private const string ReturnAddressFieldName = "ReturnAddress";
 private const string CalleeSavedRegistersFieldName = "CalleeSavedRegisters";
 private const string ArgumentRegistersFieldName = "ArgumentRegisters";
 private const string FirstGCRefMapSlotFieldName = "FirstGCRefMapSlot";

 public static Layout<MockTransitionBlock> CreateLayout(MockTarget.Architecture architecture, Layout<MockRegisterSet> calleeSavedRegistersLayout, Layout<MockRegisterSet> argumentRegistersLayout)
 => new SequentialLayoutBuilder("TransitionBlock", architecture)
 .AddPointerField(ReturnAddressFieldName)
 .AddField(CalleeSavedRegistersFieldName, calleeSavedRegistersLayout.Size)
 .AddField(ArgumentRegistersFieldName, argumentRegistersLayout.Size)
 .AddPointerField(FirstGCRefMapSlotFieldName)
 .Build<MockTransitionBlock>();

 public ulong ReturnAddress
 {
 get => ReadPointerField(ReturnAddressFieldName);
 set => WritePointerField(ReturnAddressFieldName, value);
 }

 public ulong CalleeSavedRegister
 {
 get => ReadPointerField(CalleeSavedRegistersFieldName);
 set => WritePointerField(CalleeSavedRegistersFieldName, value);
 }

 public ulong ArgumentRegister
 {
 get => ReadPointerField(ArgumentRegistersFieldName);
 set => WritePointerField(ArgumentRegistersFieldName, value);
 }
}

internal sealed class MockRegisterSet : TypedView
{
 public const string CalleeSavedRegisterName = "rbx";
 public const string ArgumentRegisterName = "rcx";
 public const string Arm64CalleeSavedRegisterName = "x19";
 public const string Arm64ArgumentRegisterName = "x0";

 public static Layout<MockRegisterSet> CreateLayout(MockTarget.Architecture architecture, string name)
 => new SequentialLayoutBuilder(name, architecture)
 .AddPointerField(name)
 .Build<MockRegisterSet>();

 public ulong Register
 {
 get => ReadPointerField(Layout.Name);
 set => WritePointerField(Layout.Name, value);
 }
}

/// <summary>
/// Helper for building a Frame chain in the mock target memory. The Frame chain is
/// terminated with the FRAME_TOP sentinel (~0 sized to the target pointer width).
Expand All@@ -168,6 +237,7 @@ internal sealed class MockFrameBuilder
 public const ulong InterpreterFrameIdentifierValue = 0x0001_F009;
 public const ulong HijackFrameIdentifierValue = 0x0001_F00A;
 public const ulong RedirectedThreadFrameIdentifierValue = 0x0001_F00B;
 public const ulong ResolveHelperFrameIdentifierValue = 0x0001_F00C;

 private readonly MockMemorySpace.Builder _builder;
 private readonly MockMemorySpace.BumpAllocator _allocator;
Expand All@@ -177,16 +247,25 @@ internal sealed class MockFrameBuilder
 public Layout<MockFrame> FrameLayout { get; }
 public Layout<MockInlinedCallFrame> InlinedCallFrameLayout { get; }
 public Layout<MockFramedMethodFrame> FramedMethodFrameLayout { get; }
 public Layout<MockResolveHelperFrame> ResolveHelperFrameLayout { get; }
 public Layout<MockFuncEvalFrame> FuncEvalFrameLayout { get; }
 public Layout<MockDebuggerEval> DebuggerEvalLayout { get; }
 public Layout<MockResumableFrame> ResumableFrameLayout { get; }
 public Layout<MockTransitionBlock> TransitionBlockLayout { get; }
 public Layout<MockRegisterSet> CalleeSavedRegistersLayout { get; }
 public Layout<MockRegisterSet> ArgumentRegistersLayout { get; }

 public MockFrameBuilder(MockMemorySpace.Builder builder)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd))
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange)
 public MockFrameBuilder(MockMemorySpace.Builder builder, string calleeSavedRegisterName, string argumentRegisterName)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd), calleeSavedRegisterName, argumentRegisterName)
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange, string? calleeSavedRegisterName = null, string? argumentRegisterName = null)
 {
 _builder = builder;
 _helpers = builder.TargetTestHelpers;
Expand All@@ -196,9 +275,13 @@ public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End
 FrameLayout = MockFrame.CreateLayout(_helpers.Arch);
 InlinedCallFrameLayout = MockInlinedCallFrame.CreateLayout(FrameLayout);
 FramedMethodFrameLayout = MockFramedMethodFrame.CreateLayout(FrameLayout);
 ResolveHelperFrameLayout = MockResolveHelperFrame.CreateLayout(FrameLayout);
 FuncEvalFrameLayout = MockFuncEvalFrame.CreateLayout(FrameLayout);
 DebuggerEvalLayout = MockDebuggerEval.CreateLayout(_helpers.Arch);
 ResumableFrameLayout = MockResumableFrame.CreateLayout(FrameLayout);
 CalleeSavedRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, calleeSavedRegisterName ?? MockRegisterSet.CalleeSavedRegisterName);
 ArgumentRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, argumentRegisterName ?? MockRegisterSet.ArgumentRegisterName);
 TransitionBlockLayout = MockTransitionBlock.CreateLayout(_helpers.Arch, CalleeSavedRegistersLayout, ArgumentRegistersLayout);
 }

 public ulong FrameTopTerminator => _terminator;
Expand DownExpand Up@@ -239,6 +322,24 @@ public MockFramedMethodFrame AddFramedMethodFrame(ulong methodDescPtr)
 return frame;
 }

 public MockResolveHelperFrame AddResolveHelperFrame(ulong transitionBlockPtr)
 {
 MockResolveHelperFrame frame = ResolveHelperFrameLayout.Create(_allocator.Allocate((ulong)ResolveHelperFrameLayout.Size, "ResolveHelperFrame"));
 frame.Identifier = ResolveHelperFrameIdentifierValue;
 frame.Next = _terminator;
 frame.TransitionBlockPtr = transitionBlockPtr;
 return frame;
 }

 public MockTransitionBlock AddTransitionBlock(ulong returnAddress, ulong calleeSavedRegister, ulong argumentRegister)
 {
 MockTransitionBlock transitionBlock = TransitionBlockLayout.Create(_allocator.Allocate((ulong)TransitionBlockLayout.Size, "TransitionBlock"));
 transitionBlock.ReturnAddress = returnAddress;
 transitionBlock.CalleeSavedRegister = calleeSavedRegister;
 transitionBlock.ArgumentRegister = argumentRegister;
 return transitionBlock;
 }

 public MockResumableFrame AddRedirectedThreadFrame(ulong targetContextPtr)
 {
 MockResumableFrame frame = ResumableFrameLayout.Create(_allocator.Allocate((ulong)ResumableFrameLayout.Size, "RedirectedThreadFrame"));
Expand Down
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(function() {
function tryTheater() {
var btn = document.querySelector('button[aria-label="Theater mode"], ytd-player #player button[title="Theater mode"]');
if (btn && !btn.classList.contains('activated')) {
btn.click();
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// Try immediately
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Add cDac contract for ResolveFrameHelper by leculver · Pull Request #129261 · dotnet/runtime · GitHub
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leculver
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Add cDac contract for ResolveFrameHelper
#129261
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0d9f706

Implement cDAC ResolveHelperFrame handling


leculver Jun 8, 2026
9f19732

Fix cDAC ResolveHelperFrame tests


leculver Jun 10, 2026
b6c8c7a

Separate ResolveHelperFrame return address handling


leculver Jun 10, 2026
3d2fcc9

Document ResolveHelperFrame in StackWalk data contract


leculver Jun 11, 2026
2a8047e

Add ARM64 coverage for ResolveHelperFrame context handling


leculver Jun 11, 2026

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4 changes: 4 additions & 0 deletions
docs/design/datacontracts/StackWalk.md

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Expand Up@@ -103,6 +103,7 @@ This contract depends on the following descriptors:
| `SoftwareExceptionFrame` | `ReturnAddress` | Return address saved in Frame |
| `FramedMethodFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock |
| `FramedMethodFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `ResolveHelperFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock (only present when `FEATURE_RESOLVE_HELPER_DISPATCH` is defined) |
@jkotasjkotasJun 18, 2026

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This was test-only code for Native AOT. I do not think it is currently reachable.
Are you able to actually hit this in tests?
@leculverleculverJun 18, 2026•

edited

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No, this is from code review only. I mostly want to make sure that we aren't missing a cDac contract for some scenario which would require servicing later. This seems to be the only coreclr!Frame that isn't wrapped. If this is pure test code that will never ship, I will close this PR. That wasn't obvious from source inspection.
@leculverleculverJun 18, 2026

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Scanning through it looks like DOTNET_JitForceControlFlowGuard=1 can still reach this, and this code is dac-ized in the legacy dac. Seems like it would be safer to wrap it in case we need to debug something where it shows up.
I'm happy to close without merging if you disagree though.
@jkotasjkotasJun 21, 2026

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I do not think it is reachable currently.
ResolveHelperFrame is only used by VSD_ResolveWorkerForInterfaceLookupSlot. VSD_ResolveWorkerForInterfaceLookupSlot is only called by JIT_InterfaceLookupForSlot. JIT_InterfaceLookupForSlot ID is CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT.CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT is never emitted by the JIT currently.
I think you can delete this whole chain if you would like.
@leculverleculverJun 21, 2026

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Thanks! I'll close this one and open a new one to do exactly that.
| `StubDispatchFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `StubDispatchFrame` | `RepresentativeMTPtr` | Pointer to Frame's method table pointer |
| `StubDispatchFrame` | `RepresentativeSlot` | Frame's method table slot |
Expand DownExpand Up@@ -401,6 +402,9 @@ The following Frame types also use this mechanism:
* CallCountingHelperFrame
* ExternalMethodFrame
* DynamicHelperFrame
* ResolveHelperFrame

`ResolveHelperFrame` additionally restores the argument registers stored in the `TransitionBlock` on all platforms (not just ARM), because the virtual stub dispatch resolve helper relies on the original argument registers to perform dispatch resolution. This mirrors native `ResolveHelperFrame::UpdateRegDisplay`. It is only present when the runtime is built with `FEATURE_RESOLVE_HELPER_DISPATCH`; when the feature is absent its type descriptor and Frame identifier are not emitted, so no Frame is ever classified as a `ResolveHelperFrame`.

#### FuncEvalFrame

Expand Down

7 changes: 7 additions & 0 deletions
src/coreclr/vm/datadescriptor/datadescriptor.inc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1098,6 +1098,13 @@ CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, TransitionBlockPtr, cdac_data<Fram
CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, MethodDescPtr, cdac_data<FramedMethodFrame>::MethodDescPtr)
CDAC_TYPE_END(FramedMethodFrame)

#ifdef FEATURE_RESOLVE_HELPER_DISPATCH
CDAC_TYPE_BEGIN(ResolveHelperFrame)
CDAC_TYPE_SIZE(sizeof(ResolveHelperFrame))
CDAC_TYPE_FIELD(ResolveHelperFrame, T_POINTER, TransitionBlockPtr, cdac_data<ResolveHelperFrame>::TransitionBlockPtr)
CDAC_TYPE_END(ResolveHelperFrame)
#endif // FEATURE_RESOLVE_HELPER_DISPATCH

#ifdef FEATURE_INTERPRETER
CDAC_TYPE_BEGIN(InterpreterFrame)
CDAC_TYPE_INDETERMINATE(InterpreterFrame)
Expand Down

8 changes: 8 additions & 0 deletions
src/coreclr/vm/frames.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -951,6 +951,14 @@ class ResolveHelperFrame : public TransitionFrame
 }

 void UpdateRegDisplay_Impl(const PREGDISPLAY, bool updateFloats = false);

 friend struct cdac_data<ResolveHelperFrame>;
};

template<>
struct cdac_data<ResolveHelperFrame>
{
 static constexpr size_t TransitionBlockPtr = offsetof(ResolveHelperFrame, m_pTransitionBlock);
};

#endif // FEATURE_RESOLVE_HELPER_DISPATCH
Expand Down

6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/AMD64FrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -58,4 +58,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
}

6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARM64FrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -48,4 +48,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
Comment thread
leculver marked this conversation as resolved.

}

7 changes: 5 additions & 2 deletions
...nostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARMFrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -46,11 +46,14 @@ public override void HandleInlinedCallFrame(InlinedCallFrame inlinedCallFrame)
 }

 public override void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public override void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 // Call the base method to handle common logic
 base.HandleTransitionFrame(framedMethodFrame);
 base.HandleTransitionBlock(transitionBlockPtr);

 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);

 // On ARM, TransitionFrames update the argument registers
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
Expand Down

17 changes: 15 additions & 2 deletions
...ostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/BaseFrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -42,20 +42,33 @@ public virtual void HandleSoftwareExceptionFrame(SoftwareExceptionFrame software
 }

 public virtual void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public virtual void HandleResolveHelperFrame(ResolveHelperFrame frame)
 => HandleTransitionBlock(frame.TransitionBlockPtr);

 public virtual void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 if (_target.GetTypeInfo(DataType.TransitionBlock).Size is not uint transitionBlockSize)
 {
 throw new InvalidOperationException("TransitionBlock size is not set");
 }

 _context.InstructionPointer = transitionBlock.ReturnAddress;
 _context.StackPointer = framedMethodFrame.TransitionBlockPtr + transitionBlockSize;
 _context.StackPointer = transitionBlockPtr + transitionBlockSize;

 Data.CalleeSavedRegisters calleeSavedRegisters = _target.ProcessedData.GetOrAdd<Data.CalleeSavedRegisters>(transitionBlock.CalleeSavedRegisters);
 UpdateFromRegisterDict(calleeSavedRegisters.Registers);
 }

 protected void UpdateArgumentRegisters(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
 UpdateFromRegisterDict(argumentRegisters.Registers);
 }

 public virtual void HandleFuncEvalFrame(FuncEvalFrame funcEvalFrame)
 {
 Data.DebuggerEval debuggerEval = _target.ProcessedData.GetOrAdd<Data.DebuggerEval>(funcEvalFrame.DebuggerEvalPtr);
Expand Down

22 changes: 19 additions & 3 deletions
...iagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/FrameHelpers.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -24,6 +24,7 @@ internal enum FrameType
 ExternalMethodFrame,
 DynamicHelperFrame,
 InterpreterFrame,
 ResolveHelperFrame,

 FuncEvalFrame,

Expand DownExpand Up@@ -141,7 +142,8 @@ public TargetPointer GetMethodDescPtr(TargetPointer framePtr)
 /// </summary>
 public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext context)
 {
 switch (GetFrameType(frame.Identifier))
 FrameType frameType = GetFrameType(frame.Identifier);
 switch (frameType)
 {
 case FrameType.InlinedCallFrame:
 Data.InlinedCallFrame inlinedCallFrame = _target.ProcessedData.GetOrAdd<Data.InlinedCallFrame>(frame.Address);
Expand All@@ -166,6 +168,11 @@ public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext co
 GetFrameHandler(context).HandleTransitionFrame(framedMethodFrame);
 return;

 case FrameType.ResolveHelperFrame:
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 GetFrameHandler(context).HandleResolveHelperFrame(resolveHelperFrame);
 return;

 case FrameType.InterpreterFrame:
 {
 // Mirrors native InterpreterFrame::SetContextToInterpMethodContextFrame
Expand DownExpand Up@@ -232,9 +239,18 @@ public TargetPointer GetReturnAddress(Data.Frame frame)
 case FrameType.CallCountingHelperFrame:
 case FrameType.ExternalMethodFrame:
 case FrameType.DynamicHelperFrame:
 Data.FramedMethodFrame fmf = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(fmf.TransitionBlockPtr);
 {
 Data.FramedMethodFrame framedMethodFrame = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 case FrameType.ResolveHelperFrame:
 {
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(resolveHelperFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 // SoftwareExceptionFrame: stored m_ReturnAddress
 case FrameType.SoftwareExceptionFrame:
Expand Down

2 changes: 2 additions & 0 deletions
...s.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/IPlatformFrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -14,6 +14,8 @@ internal interface IPlatformFrameHandler
 void HandleInlinedCallFrame(Data.InlinedCallFrame frame);
 void HandleSoftwareExceptionFrame(Data.SoftwareExceptionFrame frame);
 void HandleTransitionFrame(Data.FramedMethodFrame frame);
 void HandleTransitionBlock(TargetPointer transitionBlockPtr);
 void HandleResolveHelperFrame(Data.ResolveHelperFrame frame);
 void HandleFuncEvalFrame(Data.FuncEvalFrame frame);
 void HandleResumableFrame(Data.ResumableFrame frame);
 void HandleFaultingExceptionFrame(Data.FaultingExceptionFrame frame);
Expand Down

3 changes: 2 additions & 1 deletion
...dac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/StackWalk_1.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -77,7 +77,8 @@ public bool IsCurrentFrameResumable()
 // HijackFrame should be conditioned on the target architecture.
 return ft is FrameType.ResumableFrame
 or FrameType.RedirectedThreadFrame
 or FrameType.HijackFrame;
 or FrameType.HijackFrame
 or FrameType.ResolveHelperFrame;
 }

 /// <summary>
Expand Down

10 changes: 10 additions & 0 deletions
...cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/ResolveHelperFrame.cs

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@@ -0,0 +1,10 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

namespace Microsoft.Diagnostics.DataContractReader.Data;

[CdacType(nameof(DataType.ResolveHelperFrame))]
internal partial class ResolveHelperFrame : IData<ResolveHelperFrame>
{
 [Field] public TargetPointer TransitionBlockPtr { get; }
}

1 change: 1 addition & 0 deletions
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/DataType.cs

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Expand Up@@ -166,6 +166,7 @@ public enum DataType
 InlinedCallFrame,
 SoftwareExceptionFrame,
 FramedMethodFrame,
 ResolveHelperFrame,
Comment thread
leculver marked this conversation as resolved.

 FuncEvalFrame,
 ResumableFrame,
 FaultingExceptionFrame,
Expand Down

2 changes: 1 addition & 1 deletion
src/native/managed/cdac/tests/TestInfrastructure/TestPlaceholderTarget.cs

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Expand Up@@ -546,7 +546,7 @@ public override Target.TypeInfo GetTypeInfo(string typeName)
 public override bool TryGetTypeInfo(string typeName, out Target.TypeInfo info)
 => _typeInfoCache.TryGetValue(typeName, out info);

 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => throw new NotImplementedException();
 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => false;

 public override Target.IDataCache ProcessedData => _dataCache;
 public override ContractRegistry Contracts => _contractRegistry;
Expand Down

103 changes: 102 additions & 1 deletion
src/native/managed/cdac/tests/UnitTests/MockDescriptors/MockDescriptors.Frame.cs

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Expand Up@@ -76,6 +76,22 @@ public ulong MethodDescPtr
 }
}

internal sealed class MockResolveHelperFrame : MockFrame
{
 private const string TransitionBlockPtrFieldName = "TransitionBlockPtr";

 public static Layout<MockResolveHelperFrame> CreateLayout(Layout<MockFrame> baseLayout)
 => new SequentialLayoutBuilder("ResolveHelperFrame", baseLayout.Architecture, baseLayout)
 .AddPointerField(TransitionBlockPtrFieldName)
 .Build<MockResolveHelperFrame>();

 public ulong TransitionBlockPtr
 {
 get => ReadPointerField(TransitionBlockPtrFieldName);
 set => WritePointerField(TransitionBlockPtrFieldName, value);
 }
}

internal sealed class MockFuncEvalFrame : MockFrame
{
 // Mirrors the cDAC FuncEvalFrame data class which only reads DebuggerEvalPtr.
Expand DownExpand Up@@ -142,6 +158,59 @@ public ulong TargetContextPtr
 }
}

internal sealed class MockTransitionBlock : TypedView
{
 private const string ReturnAddressFieldName = "ReturnAddress";
 private const string CalleeSavedRegistersFieldName = "CalleeSavedRegisters";
 private const string ArgumentRegistersFieldName = "ArgumentRegisters";
 private const string FirstGCRefMapSlotFieldName = "FirstGCRefMapSlot";

 public static Layout<MockTransitionBlock> CreateLayout(MockTarget.Architecture architecture, Layout<MockRegisterSet> calleeSavedRegistersLayout, Layout<MockRegisterSet> argumentRegistersLayout)
 => new SequentialLayoutBuilder("TransitionBlock", architecture)
 .AddPointerField(ReturnAddressFieldName)
 .AddField(CalleeSavedRegistersFieldName, calleeSavedRegistersLayout.Size)
 .AddField(ArgumentRegistersFieldName, argumentRegistersLayout.Size)
 .AddPointerField(FirstGCRefMapSlotFieldName)
 .Build<MockTransitionBlock>();

 public ulong ReturnAddress
 {
 get => ReadPointerField(ReturnAddressFieldName);
 set => WritePointerField(ReturnAddressFieldName, value);
 }

 public ulong CalleeSavedRegister
 {
 get => ReadPointerField(CalleeSavedRegistersFieldName);
 set => WritePointerField(CalleeSavedRegistersFieldName, value);
 }

 public ulong ArgumentRegister
 {
 get => ReadPointerField(ArgumentRegistersFieldName);
 set => WritePointerField(ArgumentRegistersFieldName, value);
 }
}

internal sealed class MockRegisterSet : TypedView
{
 public const string CalleeSavedRegisterName = "rbx";
 public const string ArgumentRegisterName = "rcx";
 public const string Arm64CalleeSavedRegisterName = "x19";
 public const string Arm64ArgumentRegisterName = "x0";

 public static Layout<MockRegisterSet> CreateLayout(MockTarget.Architecture architecture, string name)
 => new SequentialLayoutBuilder(name, architecture)
 .AddPointerField(name)
 .Build<MockRegisterSet>();

 public ulong Register
 {
 get => ReadPointerField(Layout.Name);
 set => WritePointerField(Layout.Name, value);
 }
}

/// <summary>
/// Helper for building a Frame chain in the mock target memory. The Frame chain is
/// terminated with the FRAME_TOP sentinel (~0 sized to the target pointer width).
Expand All@@ -168,6 +237,7 @@ internal sealed class MockFrameBuilder
 public const ulong InterpreterFrameIdentifierValue = 0x0001_F009;
 public const ulong HijackFrameIdentifierValue = 0x0001_F00A;
 public const ulong RedirectedThreadFrameIdentifierValue = 0x0001_F00B;
 public const ulong ResolveHelperFrameIdentifierValue = 0x0001_F00C;

 private readonly MockMemorySpace.Builder _builder;
 private readonly MockMemorySpace.BumpAllocator _allocator;
Expand All@@ -177,16 +247,25 @@ internal sealed class MockFrameBuilder
 public Layout<MockFrame> FrameLayout { get; }
 public Layout<MockInlinedCallFrame> InlinedCallFrameLayout { get; }
 public Layout<MockFramedMethodFrame> FramedMethodFrameLayout { get; }
 public Layout<MockResolveHelperFrame> ResolveHelperFrameLayout { get; }
 public Layout<MockFuncEvalFrame> FuncEvalFrameLayout { get; }
 public Layout<MockDebuggerEval> DebuggerEvalLayout { get; }
 public Layout<MockResumableFrame> ResumableFrameLayout { get; }
 public Layout<MockTransitionBlock> TransitionBlockLayout { get; }
 public Layout<MockRegisterSet> CalleeSavedRegistersLayout { get; }
 public Layout<MockRegisterSet> ArgumentRegistersLayout { get; }

 public MockFrameBuilder(MockMemorySpace.Builder builder)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd))
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange)
 public MockFrameBuilder(MockMemorySpace.Builder builder, string calleeSavedRegisterName, string argumentRegisterName)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd), calleeSavedRegisterName, argumentRegisterName)
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange, string? calleeSavedRegisterName = null, string? argumentRegisterName = null)
 {
 _builder = builder;
 _helpers = builder.TargetTestHelpers;
Expand All@@ -196,9 +275,13 @@ public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End
 FrameLayout = MockFrame.CreateLayout(_helpers.Arch);
 InlinedCallFrameLayout = MockInlinedCallFrame.CreateLayout(FrameLayout);
 FramedMethodFrameLayout = MockFramedMethodFrame.CreateLayout(FrameLayout);
 ResolveHelperFrameLayout = MockResolveHelperFrame.CreateLayout(FrameLayout);
 FuncEvalFrameLayout = MockFuncEvalFrame.CreateLayout(FrameLayout);
 DebuggerEvalLayout = MockDebuggerEval.CreateLayout(_helpers.Arch);
 ResumableFrameLayout = MockResumableFrame.CreateLayout(FrameLayout);
 CalleeSavedRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, calleeSavedRegisterName ?? MockRegisterSet.CalleeSavedRegisterName);
 ArgumentRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, argumentRegisterName ?? MockRegisterSet.ArgumentRegisterName);
 TransitionBlockLayout = MockTransitionBlock.CreateLayout(_helpers.Arch, CalleeSavedRegistersLayout, ArgumentRegistersLayout);
 }

 public ulong FrameTopTerminator => _terminator;
Expand DownExpand Up@@ -239,6 +322,24 @@ public MockFramedMethodFrame AddFramedMethodFrame(ulong methodDescPtr)
 return frame;
 }

 public MockResolveHelperFrame AddResolveHelperFrame(ulong transitionBlockPtr)
 {
 MockResolveHelperFrame frame = ResolveHelperFrameLayout.Create(_allocator.Allocate((ulong)ResolveHelperFrameLayout.Size, "ResolveHelperFrame"));
 frame.Identifier = ResolveHelperFrameIdentifierValue;
 frame.Next = _terminator;
 frame.TransitionBlockPtr = transitionBlockPtr;
 return frame;
 }

 public MockTransitionBlock AddTransitionBlock(ulong returnAddress, ulong calleeSavedRegister, ulong argumentRegister)
 {
 MockTransitionBlock transitionBlock = TransitionBlockLayout.Create(_allocator.Allocate((ulong)TransitionBlockLayout.Size, "TransitionBlock"));
 transitionBlock.ReturnAddress = returnAddress;
 transitionBlock.CalleeSavedRegister = calleeSavedRegister;
 transitionBlock.ArgumentRegister = argumentRegister;
 return transitionBlock;
 }

 public MockResumableFrame AddRedirectedThreadFrame(ulong targetContextPtr)
 {
 MockResumableFrame frame = ResumableFrameLayout.Create(_allocator.Allocate((ulong)ResumableFrameLayout.Size, "RedirectedThreadFrame"));
Expand Down
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Add cDac contract for ResolveFrameHelper by leculver · Pull Request #129261 · dotnet/runtime · GitHub
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Add cDac contract for ResolveFrameHelper
#129261
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0d9f706

Implement cDAC ResolveHelperFrame handling


leculver Jun 8, 2026
9f19732

Fix cDAC ResolveHelperFrame tests


leculver Jun 10, 2026
b6c8c7a

Separate ResolveHelperFrame return address handling


leculver Jun 10, 2026
3d2fcc9

Document ResolveHelperFrame in StackWalk data contract


leculver Jun 11, 2026
2a8047e

Add ARM64 coverage for ResolveHelperFrame context handling


leculver Jun 11, 2026

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4 changes: 4 additions & 0 deletions
docs/design/datacontracts/StackWalk.md

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Expand Up@@ -103,6 +103,7 @@ This contract depends on the following descriptors:
| `SoftwareExceptionFrame` | `ReturnAddress` | Return address saved in Frame |
| `FramedMethodFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock |
| `FramedMethodFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `ResolveHelperFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock (only present when `FEATURE_RESOLVE_HELPER_DISPATCH` is defined) |
@jkotasjkotasJun 18, 2026

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This was test-only code for Native AOT. I do not think it is currently reachable.
Are you able to actually hit this in tests?
@leculverleculverJun 18, 2026•

edited

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No, this is from code review only. I mostly want to make sure that we aren't missing a cDac contract for some scenario which would require servicing later. This seems to be the only coreclr!Frame that isn't wrapped. If this is pure test code that will never ship, I will close this PR. That wasn't obvious from source inspection.
@leculverleculverJun 18, 2026

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Scanning through it looks like DOTNET_JitForceControlFlowGuard=1 can still reach this, and this code is dac-ized in the legacy dac. Seems like it would be safer to wrap it in case we need to debug something where it shows up.
I'm happy to close without merging if you disagree though.
@jkotasjkotasJun 21, 2026

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I do not think it is reachable currently.
ResolveHelperFrame is only used by VSD_ResolveWorkerForInterfaceLookupSlot. VSD_ResolveWorkerForInterfaceLookupSlot is only called by JIT_InterfaceLookupForSlot. JIT_InterfaceLookupForSlot ID is CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT.CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT is never emitted by the JIT currently.
I think you can delete this whole chain if you would like.
@leculverleculverJun 21, 2026

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Thanks! I'll close this one and open a new one to do exactly that.
| `StubDispatchFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `StubDispatchFrame` | `RepresentativeMTPtr` | Pointer to Frame's method table pointer |
| `StubDispatchFrame` | `RepresentativeSlot` | Frame's method table slot |
Expand DownExpand Up@@ -401,6 +402,9 @@ The following Frame types also use this mechanism:
* CallCountingHelperFrame
* ExternalMethodFrame
* DynamicHelperFrame
* ResolveHelperFrame

`ResolveHelperFrame` additionally restores the argument registers stored in the `TransitionBlock` on all platforms (not just ARM), because the virtual stub dispatch resolve helper relies on the original argument registers to perform dispatch resolution. This mirrors native `ResolveHelperFrame::UpdateRegDisplay`. It is only present when the runtime is built with `FEATURE_RESOLVE_HELPER_DISPATCH`; when the feature is absent its type descriptor and Frame identifier are not emitted, so no Frame is ever classified as a `ResolveHelperFrame`.

#### FuncEvalFrame

Expand Down

7 changes: 7 additions & 0 deletions
src/coreclr/vm/datadescriptor/datadescriptor.inc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1098,6 +1098,13 @@ CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, TransitionBlockPtr, cdac_data<Fram
CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, MethodDescPtr, cdac_data<FramedMethodFrame>::MethodDescPtr)
CDAC_TYPE_END(FramedMethodFrame)

#ifdef FEATURE_RESOLVE_HELPER_DISPATCH
CDAC_TYPE_BEGIN(ResolveHelperFrame)
CDAC_TYPE_SIZE(sizeof(ResolveHelperFrame))
CDAC_TYPE_FIELD(ResolveHelperFrame, T_POINTER, TransitionBlockPtr, cdac_data<ResolveHelperFrame>::TransitionBlockPtr)
CDAC_TYPE_END(ResolveHelperFrame)
#endif // FEATURE_RESOLVE_HELPER_DISPATCH

#ifdef FEATURE_INTERPRETER
CDAC_TYPE_BEGIN(InterpreterFrame)
CDAC_TYPE_INDETERMINATE(InterpreterFrame)
Expand Down

8 changes: 8 additions & 0 deletions
src/coreclr/vm/frames.h

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Expand Up@@ -951,6 +951,14 @@ class ResolveHelperFrame : public TransitionFrame
 }

 void UpdateRegDisplay_Impl(const PREGDISPLAY, bool updateFloats = false);

 friend struct cdac_data<ResolveHelperFrame>;
};

template<>
struct cdac_data<ResolveHelperFrame>
{
 static constexpr size_t TransitionBlockPtr = offsetof(ResolveHelperFrame, m_pTransitionBlock);
};

#endif // FEATURE_RESOLVE_HELPER_DISPATCH
Expand Down

6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/AMD64FrameHandler.cs

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Expand Up@@ -58,4 +58,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
}

6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARM64FrameHandler.cs

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Expand Up@@ -48,4 +48,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
Comment thread
leculver marked this conversation as resolved.

}

7 changes: 5 additions & 2 deletions
...nostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARMFrameHandler.cs

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Expand Up@@ -46,11 +46,14 @@ public override void HandleInlinedCallFrame(InlinedCallFrame inlinedCallFrame)
 }

 public override void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public override void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 // Call the base method to handle common logic
 base.HandleTransitionFrame(framedMethodFrame);
 base.HandleTransitionBlock(transitionBlockPtr);

 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);

 // On ARM, TransitionFrames update the argument registers
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
Expand Down

17 changes: 15 additions & 2 deletions
...ostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/BaseFrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -42,20 +42,33 @@ public virtual void HandleSoftwareExceptionFrame(SoftwareExceptionFrame software
 }

 public virtual void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public virtual void HandleResolveHelperFrame(ResolveHelperFrame frame)
 => HandleTransitionBlock(frame.TransitionBlockPtr);

 public virtual void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 if (_target.GetTypeInfo(DataType.TransitionBlock).Size is not uint transitionBlockSize)
 {
 throw new InvalidOperationException("TransitionBlock size is not set");
 }

 _context.InstructionPointer = transitionBlock.ReturnAddress;
 _context.StackPointer = framedMethodFrame.TransitionBlockPtr + transitionBlockSize;
 _context.StackPointer = transitionBlockPtr + transitionBlockSize;

 Data.CalleeSavedRegisters calleeSavedRegisters = _target.ProcessedData.GetOrAdd<Data.CalleeSavedRegisters>(transitionBlock.CalleeSavedRegisters);
 UpdateFromRegisterDict(calleeSavedRegisters.Registers);
 }

 protected void UpdateArgumentRegisters(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
 UpdateFromRegisterDict(argumentRegisters.Registers);
 }

 public virtual void HandleFuncEvalFrame(FuncEvalFrame funcEvalFrame)
 {
 Data.DebuggerEval debuggerEval = _target.ProcessedData.GetOrAdd<Data.DebuggerEval>(funcEvalFrame.DebuggerEvalPtr);
Expand Down

22 changes: 19 additions & 3 deletions
...iagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/FrameHelpers.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -24,6 +24,7 @@ internal enum FrameType
 ExternalMethodFrame,
 DynamicHelperFrame,
 InterpreterFrame,
 ResolveHelperFrame,

 FuncEvalFrame,

Expand DownExpand Up@@ -141,7 +142,8 @@ public TargetPointer GetMethodDescPtr(TargetPointer framePtr)
 /// </summary>
 public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext context)
 {
 switch (GetFrameType(frame.Identifier))
 FrameType frameType = GetFrameType(frame.Identifier);
 switch (frameType)
 {
 case FrameType.InlinedCallFrame:
 Data.InlinedCallFrame inlinedCallFrame = _target.ProcessedData.GetOrAdd<Data.InlinedCallFrame>(frame.Address);
Expand All@@ -166,6 +168,11 @@ public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext co
 GetFrameHandler(context).HandleTransitionFrame(framedMethodFrame);
 return;

 case FrameType.ResolveHelperFrame:
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 GetFrameHandler(context).HandleResolveHelperFrame(resolveHelperFrame);
 return;

 case FrameType.InterpreterFrame:
 {
 // Mirrors native InterpreterFrame::SetContextToInterpMethodContextFrame
Expand DownExpand Up@@ -232,9 +239,18 @@ public TargetPointer GetReturnAddress(Data.Frame frame)
 case FrameType.CallCountingHelperFrame:
 case FrameType.ExternalMethodFrame:
 case FrameType.DynamicHelperFrame:
 Data.FramedMethodFrame fmf = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(fmf.TransitionBlockPtr);
 {
 Data.FramedMethodFrame framedMethodFrame = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 case FrameType.ResolveHelperFrame:
 {
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(resolveHelperFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 // SoftwareExceptionFrame: stored m_ReturnAddress
 case FrameType.SoftwareExceptionFrame:
Expand Down

2 changes: 2 additions & 0 deletions
...s.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/IPlatformFrameHandler.cs

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Expand Up@@ -14,6 +14,8 @@ internal interface IPlatformFrameHandler
 void HandleInlinedCallFrame(Data.InlinedCallFrame frame);
 void HandleSoftwareExceptionFrame(Data.SoftwareExceptionFrame frame);
 void HandleTransitionFrame(Data.FramedMethodFrame frame);
 void HandleTransitionBlock(TargetPointer transitionBlockPtr);
 void HandleResolveHelperFrame(Data.ResolveHelperFrame frame);
 void HandleFuncEvalFrame(Data.FuncEvalFrame frame);
 void HandleResumableFrame(Data.ResumableFrame frame);
 void HandleFaultingExceptionFrame(Data.FaultingExceptionFrame frame);
Expand Down

3 changes: 2 additions & 1 deletion
...dac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/StackWalk_1.cs

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Expand Up@@ -77,7 +77,8 @@ public bool IsCurrentFrameResumable()
 // HijackFrame should be conditioned on the target architecture.
 return ft is FrameType.ResumableFrame
 or FrameType.RedirectedThreadFrame
 or FrameType.HijackFrame;
 or FrameType.HijackFrame
 or FrameType.ResolveHelperFrame;
 }

 /// <summary>
Expand Down

10 changes: 10 additions & 0 deletions
...cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/ResolveHelperFrame.cs

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@@ -0,0 +1,10 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

namespace Microsoft.Diagnostics.DataContractReader.Data;

[CdacType(nameof(DataType.ResolveHelperFrame))]
internal partial class ResolveHelperFrame : IData<ResolveHelperFrame>
{
 [Field] public TargetPointer TransitionBlockPtr { get; }
}

1 change: 1 addition & 0 deletions
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/DataType.cs

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Expand Up@@ -166,6 +166,7 @@ public enum DataType
 InlinedCallFrame,
 SoftwareExceptionFrame,
 FramedMethodFrame,
 ResolveHelperFrame,
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 FuncEvalFrame,
 ResumableFrame,
 FaultingExceptionFrame,
Expand Down

2 changes: 1 addition & 1 deletion
src/native/managed/cdac/tests/TestInfrastructure/TestPlaceholderTarget.cs

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Expand Up@@ -546,7 +546,7 @@ public override Target.TypeInfo GetTypeInfo(string typeName)
 public override bool TryGetTypeInfo(string typeName, out Target.TypeInfo info)
 => _typeInfoCache.TryGetValue(typeName, out info);

 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => throw new NotImplementedException();
 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => false;

 public override Target.IDataCache ProcessedData => _dataCache;
 public override ContractRegistry Contracts => _contractRegistry;
Expand Down

103 changes: 102 additions & 1 deletion
src/native/managed/cdac/tests/UnitTests/MockDescriptors/MockDescriptors.Frame.cs

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Expand Up@@ -76,6 +76,22 @@ public ulong MethodDescPtr
 }
}

internal sealed class MockResolveHelperFrame : MockFrame
{
 private const string TransitionBlockPtrFieldName = "TransitionBlockPtr";

 public static Layout<MockResolveHelperFrame> CreateLayout(Layout<MockFrame> baseLayout)
 => new SequentialLayoutBuilder("ResolveHelperFrame", baseLayout.Architecture, baseLayout)
 .AddPointerField(TransitionBlockPtrFieldName)
 .Build<MockResolveHelperFrame>();

 public ulong TransitionBlockPtr
 {
 get => ReadPointerField(TransitionBlockPtrFieldName);
 set => WritePointerField(TransitionBlockPtrFieldName, value);
 }
}

internal sealed class MockFuncEvalFrame : MockFrame
{
 // Mirrors the cDAC FuncEvalFrame data class which only reads DebuggerEvalPtr.
Expand DownExpand Up@@ -142,6 +158,59 @@ public ulong TargetContextPtr
 }
}

internal sealed class MockTransitionBlock : TypedView
{
 private const string ReturnAddressFieldName = "ReturnAddress";
 private const string CalleeSavedRegistersFieldName = "CalleeSavedRegisters";
 private const string ArgumentRegistersFieldName = "ArgumentRegisters";
 private const string FirstGCRefMapSlotFieldName = "FirstGCRefMapSlot";

 public static Layout<MockTransitionBlock> CreateLayout(MockTarget.Architecture architecture, Layout<MockRegisterSet> calleeSavedRegistersLayout, Layout<MockRegisterSet> argumentRegistersLayout)
 => new SequentialLayoutBuilder("TransitionBlock", architecture)
 .AddPointerField(ReturnAddressFieldName)
 .AddField(CalleeSavedRegistersFieldName, calleeSavedRegistersLayout.Size)
 .AddField(ArgumentRegistersFieldName, argumentRegistersLayout.Size)
 .AddPointerField(FirstGCRefMapSlotFieldName)
 .Build<MockTransitionBlock>();

 public ulong ReturnAddress
 {
 get => ReadPointerField(ReturnAddressFieldName);
 set => WritePointerField(ReturnAddressFieldName, value);
 }

 public ulong CalleeSavedRegister
 {
 get => ReadPointerField(CalleeSavedRegistersFieldName);
 set => WritePointerField(CalleeSavedRegistersFieldName, value);
 }

 public ulong ArgumentRegister
 {
 get => ReadPointerField(ArgumentRegistersFieldName);
 set => WritePointerField(ArgumentRegistersFieldName, value);
 }
}

internal sealed class MockRegisterSet : TypedView
{
 public const string CalleeSavedRegisterName = "rbx";
 public const string ArgumentRegisterName = "rcx";
 public const string Arm64CalleeSavedRegisterName = "x19";
 public const string Arm64ArgumentRegisterName = "x0";

 public static Layout<MockRegisterSet> CreateLayout(MockTarget.Architecture architecture, string name)
 => new SequentialLayoutBuilder(name, architecture)
 .AddPointerField(name)
 .Build<MockRegisterSet>();

 public ulong Register
 {
 get => ReadPointerField(Layout.Name);
 set => WritePointerField(Layout.Name, value);
 }
}

/// <summary>
/// Helper for building a Frame chain in the mock target memory. The Frame chain is
/// terminated with the FRAME_TOP sentinel (~0 sized to the target pointer width).
Expand All@@ -168,6 +237,7 @@ internal sealed class MockFrameBuilder
 public const ulong InterpreterFrameIdentifierValue = 0x0001_F009;
 public const ulong HijackFrameIdentifierValue = 0x0001_F00A;
 public const ulong RedirectedThreadFrameIdentifierValue = 0x0001_F00B;
 public const ulong ResolveHelperFrameIdentifierValue = 0x0001_F00C;

 private readonly MockMemorySpace.Builder _builder;
 private readonly MockMemorySpace.BumpAllocator _allocator;
Expand All@@ -177,16 +247,25 @@ internal sealed class MockFrameBuilder
 public Layout<MockFrame> FrameLayout { get; }
 public Layout<MockInlinedCallFrame> InlinedCallFrameLayout { get; }
 public Layout<MockFramedMethodFrame> FramedMethodFrameLayout { get; }
 public Layout<MockResolveHelperFrame> ResolveHelperFrameLayout { get; }
 public Layout<MockFuncEvalFrame> FuncEvalFrameLayout { get; }
 public Layout<MockDebuggerEval> DebuggerEvalLayout { get; }
 public Layout<MockResumableFrame> ResumableFrameLayout { get; }
 public Layout<MockTransitionBlock> TransitionBlockLayout { get; }
 public Layout<MockRegisterSet> CalleeSavedRegistersLayout { get; }
 public Layout<MockRegisterSet> ArgumentRegistersLayout { get; }

 public MockFrameBuilder(MockMemorySpace.Builder builder)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd))
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange)
 public MockFrameBuilder(MockMemorySpace.Builder builder, string calleeSavedRegisterName, string argumentRegisterName)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd), calleeSavedRegisterName, argumentRegisterName)
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange, string? calleeSavedRegisterName = null, string? argumentRegisterName = null)
 {
 _builder = builder;
 _helpers = builder.TargetTestHelpers;
Expand All@@ -196,9 +275,13 @@ public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End
 FrameLayout = MockFrame.CreateLayout(_helpers.Arch);
 InlinedCallFrameLayout = MockInlinedCallFrame.CreateLayout(FrameLayout);
 FramedMethodFrameLayout = MockFramedMethodFrame.CreateLayout(FrameLayout);
 ResolveHelperFrameLayout = MockResolveHelperFrame.CreateLayout(FrameLayout);
 FuncEvalFrameLayout = MockFuncEvalFrame.CreateLayout(FrameLayout);
 DebuggerEvalLayout = MockDebuggerEval.CreateLayout(_helpers.Arch);
 ResumableFrameLayout = MockResumableFrame.CreateLayout(FrameLayout);
 CalleeSavedRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, calleeSavedRegisterName ?? MockRegisterSet.CalleeSavedRegisterName);
 ArgumentRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, argumentRegisterName ?? MockRegisterSet.ArgumentRegisterName);
 TransitionBlockLayout = MockTransitionBlock.CreateLayout(_helpers.Arch, CalleeSavedRegistersLayout, ArgumentRegistersLayout);
 }

 public ulong FrameTopTerminator => _terminator;
Expand DownExpand Up@@ -239,6 +322,24 @@ public MockFramedMethodFrame AddFramedMethodFrame(ulong methodDescPtr)
 return frame;
 }

 public MockResolveHelperFrame AddResolveHelperFrame(ulong transitionBlockPtr)
 {
 MockResolveHelperFrame frame = ResolveHelperFrameLayout.Create(_allocator.Allocate((ulong)ResolveHelperFrameLayout.Size, "ResolveHelperFrame"));
 frame.Identifier = ResolveHelperFrameIdentifierValue;
 frame.Next = _terminator;
 frame.TransitionBlockPtr = transitionBlockPtr;
 return frame;
 }

 public MockTransitionBlock AddTransitionBlock(ulong returnAddress, ulong calleeSavedRegister, ulong argumentRegister)
 {
 MockTransitionBlock transitionBlock = TransitionBlockLayout.Create(_allocator.Allocate((ulong)TransitionBlockLayout.Size, "TransitionBlock"));
 transitionBlock.ReturnAddress = returnAddress;
 transitionBlock.CalleeSavedRegister = calleeSavedRegister;
 transitionBlock.ArgumentRegister = argumentRegister;
 return transitionBlock;
 }

 public MockResumableFrame AddRedirectedThreadFrame(ulong targetContextPtr)
 {
 MockResumableFrame frame = ResumableFrameLayout.Create(_allocator.Allocate((ulong)ResumableFrameLayout.Size, "RedirectedThreadFrame"));
Expand Down
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, 'i');
if (__m === '*' || __re.test(location.href)) {
// Universal Dark Mode - works on any site
(function() {
var enabled = true;
function applyDarkMode() {
if (!enabled) return;
// Create style element if it doesn't exist
var style = document.getElementById('universal-dark-mode-style');
if (!style) {
style = document.createElement('style');
style.id = 'universal-dark-mode-style';
document.head.appendChild(style);
}
// Dark mode CSS - inverts colors but preserves images/video
style.textContent = '
/* Invert everything except media */
html {
filter: invert(1) hue-rotate(180deg) !important;
background: #1a1a2e !important;
}
/* Restore images, videos, iframes, canvas */
img, video, iframe, canvas, svg, picture, [style*="background-image"] {
filter: invert(1) hue-rotate(180deg) !important;
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/* Preserve specific elements that should not be inverted */
.no-dark-mode, .no-dark-mode *,
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border-color: #444 !important;
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::-webkit-scrollbar { background: #1a1a2e !important; }
::-webkit-scrollbar-thumb { background: #444 !important; }
::-webkit-scrollbar-thumb:hover { background: #555 !important; }
/* Selection */
::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }
';
}
function removeDarkMode() {
var style = document.getElementById('universal-dark-mode-style');
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}
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if (enabled) {
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} else {
removeDarkMode();
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if (enabled && !document.getElementById('universal-dark-mode-style')) {
applyDarkMode();
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console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');
})();
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Add cDac contract for ResolveFrameHelper by leculver · Pull Request #129261 · dotnet/runtime · GitHub
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Add cDac contract for ResolveFrameHelper
#129261
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0d9f706

Implement cDAC ResolveHelperFrame handling


leculver Jun 8, 2026
9f19732

Fix cDAC ResolveHelperFrame tests


leculver Jun 10, 2026
b6c8c7a

Separate ResolveHelperFrame return address handling


leculver Jun 10, 2026
3d2fcc9

Document ResolveHelperFrame in StackWalk data contract


leculver Jun 11, 2026
2a8047e

Add ARM64 coverage for ResolveHelperFrame context handling


leculver Jun 11, 2026

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4 changes: 4 additions & 0 deletions
docs/design/datacontracts/StackWalk.md

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Original file line numberDiff line numberDiff line change
Expand Up@@ -103,6 +103,7 @@ This contract depends on the following descriptors:
| `SoftwareExceptionFrame` | `ReturnAddress` | Return address saved in Frame |
| `FramedMethodFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock |
| `FramedMethodFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `ResolveHelperFrame` | `TransitionBlockPtr` | Pointer to Frame's TransitionBlock (only present when `FEATURE_RESOLVE_HELPER_DISPATCH` is defined) |
@jkotasjkotasJun 18, 2026

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This was test-only code for Native AOT. I do not think it is currently reachable.
Are you able to actually hit this in tests?
@leculverleculverJun 18, 2026•

edited

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No, this is from code review only. I mostly want to make sure that we aren't missing a cDac contract for some scenario which would require servicing later. This seems to be the only coreclr!Frame that isn't wrapped. If this is pure test code that will never ship, I will close this PR. That wasn't obvious from source inspection.
@leculverleculverJun 18, 2026

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Scanning through it looks like DOTNET_JitForceControlFlowGuard=1 can still reach this, and this code is dac-ized in the legacy dac. Seems like it would be safer to wrap it in case we need to debug something where it shows up.
I'm happy to close without merging if you disagree though.
@jkotasjkotasJun 21, 2026

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I do not think it is reachable currently.
ResolveHelperFrame is only used by VSD_ResolveWorkerForInterfaceLookupSlot. VSD_ResolveWorkerForInterfaceLookupSlot is only called by JIT_InterfaceLookupForSlot. JIT_InterfaceLookupForSlot ID is CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT.CORINFO_HELP_INTERFACELOOKUP_FOR_SLOT is never emitted by the JIT currently.
I think you can delete this whole chain if you would like.
@leculverleculverJun 21, 2026

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Thanks! I'll close this one and open a new one to do exactly that.
| `StubDispatchFrame` | `MethodDescPtr` | Pointer to Frame's method desc |
| `StubDispatchFrame` | `RepresentativeMTPtr` | Pointer to Frame's method table pointer |
| `StubDispatchFrame` | `RepresentativeSlot` | Frame's method table slot |
Expand DownExpand Up@@ -401,6 +402,9 @@ The following Frame types also use this mechanism:
* CallCountingHelperFrame
* ExternalMethodFrame
* DynamicHelperFrame
* ResolveHelperFrame

`ResolveHelperFrame` additionally restores the argument registers stored in the `TransitionBlock` on all platforms (not just ARM), because the virtual stub dispatch resolve helper relies on the original argument registers to perform dispatch resolution. This mirrors native `ResolveHelperFrame::UpdateRegDisplay`. It is only present when the runtime is built with `FEATURE_RESOLVE_HELPER_DISPATCH`; when the feature is absent its type descriptor and Frame identifier are not emitted, so no Frame is ever classified as a `ResolveHelperFrame`.

#### FuncEvalFrame

Expand Down

7 changes: 7 additions & 0 deletions
src/coreclr/vm/datadescriptor/datadescriptor.inc

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Original file line numberDiff line numberDiff line change
Expand Up@@ -1098,6 +1098,13 @@ CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, TransitionBlockPtr, cdac_data<Fram
CDAC_TYPE_FIELD(FramedMethodFrame, T_POINTER, MethodDescPtr, cdac_data<FramedMethodFrame>::MethodDescPtr)
CDAC_TYPE_END(FramedMethodFrame)

#ifdef FEATURE_RESOLVE_HELPER_DISPATCH
CDAC_TYPE_BEGIN(ResolveHelperFrame)
CDAC_TYPE_SIZE(sizeof(ResolveHelperFrame))
CDAC_TYPE_FIELD(ResolveHelperFrame, T_POINTER, TransitionBlockPtr, cdac_data<ResolveHelperFrame>::TransitionBlockPtr)
CDAC_TYPE_END(ResolveHelperFrame)
#endif // FEATURE_RESOLVE_HELPER_DISPATCH

#ifdef FEATURE_INTERPRETER
CDAC_TYPE_BEGIN(InterpreterFrame)
CDAC_TYPE_INDETERMINATE(InterpreterFrame)
Expand Down

8 changes: 8 additions & 0 deletions
src/coreclr/vm/frames.h

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Original file line numberDiff line numberDiff line change
Expand Up@@ -951,6 +951,14 @@ class ResolveHelperFrame : public TransitionFrame
 }

 void UpdateRegDisplay_Impl(const PREGDISPLAY, bool updateFloats = false);

 friend struct cdac_data<ResolveHelperFrame>;
};

template<>
struct cdac_data<ResolveHelperFrame>
{
 static constexpr size_t TransitionBlockPtr = offsetof(ResolveHelperFrame, m_pTransitionBlock);
};

#endif // FEATURE_RESOLVE_HELPER_DISPATCH
Expand Down

6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/AMD64FrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -58,4 +58,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
}

6 changes: 6 additions & 0 deletions
...stics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARM64FrameHandler.cs

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Expand Up@@ -48,4 +48,10 @@ public override void HandleFaultingExceptionFrame(FaultingExceptionFrame frame)
 // that does not support holding any extended state.
 _holder.Context.ContextFlags &= ~(uint)(ContextFlagsValues.CONTEXT_XSTATE & ContextFlagsValues.CONTEXT_AREA_MASK);
 }

 public override void HandleResolveHelperFrame(ResolveHelperFrame frame)
 {
 base.HandleResolveHelperFrame(frame);
 UpdateArgumentRegisters(frame.TransitionBlockPtr);
 }
Comment thread
leculver marked this conversation as resolved.

}

7 changes: 5 additions & 2 deletions
...nostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/ARMFrameHandler.cs

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Expand Up@@ -46,11 +46,14 @@ public override void HandleInlinedCallFrame(InlinedCallFrame inlinedCallFrame)
 }

 public override void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public override void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 // Call the base method to handle common logic
 base.HandleTransitionFrame(framedMethodFrame);
 base.HandleTransitionBlock(transitionBlockPtr);

 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);

 // On ARM, TransitionFrames update the argument registers
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
Expand Down

17 changes: 15 additions & 2 deletions
...ostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/BaseFrameHandler.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -42,20 +42,33 @@ public virtual void HandleSoftwareExceptionFrame(SoftwareExceptionFrame software
 }

 public virtual void HandleTransitionFrame(FramedMethodFrame framedMethodFrame)
 => HandleTransitionBlock(framedMethodFrame.TransitionBlockPtr);

 public virtual void HandleResolveHelperFrame(ResolveHelperFrame frame)
 => HandleTransitionBlock(frame.TransitionBlockPtr);

 public virtual void HandleTransitionBlock(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 if (_target.GetTypeInfo(DataType.TransitionBlock).Size is not uint transitionBlockSize)
 {
 throw new InvalidOperationException("TransitionBlock size is not set");
 }

 _context.InstructionPointer = transitionBlock.ReturnAddress;
 _context.StackPointer = framedMethodFrame.TransitionBlockPtr + transitionBlockSize;
 _context.StackPointer = transitionBlockPtr + transitionBlockSize;

 Data.CalleeSavedRegisters calleeSavedRegisters = _target.ProcessedData.GetOrAdd<Data.CalleeSavedRegisters>(transitionBlock.CalleeSavedRegisters);
 UpdateFromRegisterDict(calleeSavedRegisters.Registers);
 }

 protected void UpdateArgumentRegisters(TargetPointer transitionBlockPtr)
 {
 Data.TransitionBlock transitionBlock = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(transitionBlockPtr);
 Data.ArgumentRegisters argumentRegisters = _target.ProcessedData.GetOrAdd<Data.ArgumentRegisters>(transitionBlock.ArgumentRegisters);
 UpdateFromRegisterDict(argumentRegisters.Registers);
 }

 public virtual void HandleFuncEvalFrame(FuncEvalFrame funcEvalFrame)
 {
 Data.DebuggerEval debuggerEval = _target.ProcessedData.GetOrAdd<Data.DebuggerEval>(funcEvalFrame.DebuggerEvalPtr);
Expand Down

22 changes: 19 additions & 3 deletions
...iagnostics.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/FrameHelpers.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -24,6 +24,7 @@ internal enum FrameType
 ExternalMethodFrame,
 DynamicHelperFrame,
 InterpreterFrame,
 ResolveHelperFrame,

 FuncEvalFrame,

Expand DownExpand Up@@ -141,7 +142,8 @@ public TargetPointer GetMethodDescPtr(TargetPointer framePtr)
 /// </summary>
 public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext context)
 {
 switch (GetFrameType(frame.Identifier))
 FrameType frameType = GetFrameType(frame.Identifier);
 switch (frameType)
 {
 case FrameType.InlinedCallFrame:
 Data.InlinedCallFrame inlinedCallFrame = _target.ProcessedData.GetOrAdd<Data.InlinedCallFrame>(frame.Address);
Expand All@@ -166,6 +168,11 @@ public void UpdateContextFromFrame(Data.Frame frame, IPlatformAgnosticContext co
 GetFrameHandler(context).HandleTransitionFrame(framedMethodFrame);
 return;

 case FrameType.ResolveHelperFrame:
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 GetFrameHandler(context).HandleResolveHelperFrame(resolveHelperFrame);
 return;

 case FrameType.InterpreterFrame:
 {
 // Mirrors native InterpreterFrame::SetContextToInterpMethodContextFrame
Expand DownExpand Up@@ -232,9 +239,18 @@ public TargetPointer GetReturnAddress(Data.Frame frame)
 case FrameType.CallCountingHelperFrame:
 case FrameType.ExternalMethodFrame:
 case FrameType.DynamicHelperFrame:
 Data.FramedMethodFrame fmf = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(fmf.TransitionBlockPtr);
 {
 Data.FramedMethodFrame framedMethodFrame = _target.ProcessedData.GetOrAdd<Data.FramedMethodFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(framedMethodFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 case FrameType.ResolveHelperFrame:
 {
 Data.ResolveHelperFrame resolveHelperFrame = _target.ProcessedData.GetOrAdd<Data.ResolveHelperFrame>(frame.Address);
 Data.TransitionBlock tb = _target.ProcessedData.GetOrAdd<Data.TransitionBlock>(resolveHelperFrame.TransitionBlockPtr);
 return tb.ReturnAddress;
 }

 // SoftwareExceptionFrame: stored m_ReturnAddress
 case FrameType.SoftwareExceptionFrame:
Expand Down

2 changes: 2 additions & 0 deletions
...s.DataContractReader.Contracts/Contracts/StackWalk/FrameHandling/IPlatformFrameHandler.cs

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Expand Up@@ -14,6 +14,8 @@ internal interface IPlatformFrameHandler
 void HandleInlinedCallFrame(Data.InlinedCallFrame frame);
 void HandleSoftwareExceptionFrame(Data.SoftwareExceptionFrame frame);
 void HandleTransitionFrame(Data.FramedMethodFrame frame);
 void HandleTransitionBlock(TargetPointer transitionBlockPtr);
 void HandleResolveHelperFrame(Data.ResolveHelperFrame frame);
 void HandleFuncEvalFrame(Data.FuncEvalFrame frame);
 void HandleResumableFrame(Data.ResumableFrame frame);
 void HandleFaultingExceptionFrame(Data.FaultingExceptionFrame frame);
Expand Down

3 changes: 2 additions & 1 deletion
...dac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/StackWalk/StackWalk_1.cs

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Expand Up@@ -77,7 +77,8 @@ public bool IsCurrentFrameResumable()
 // HijackFrame should be conditioned on the target architecture.
 return ft is FrameType.ResumableFrame
 or FrameType.RedirectedThreadFrame
 or FrameType.HijackFrame;
 or FrameType.HijackFrame
 or FrameType.ResolveHelperFrame;
 }

 /// <summary>
Expand Down

10 changes: 10 additions & 0 deletions
...cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Frames/ResolveHelperFrame.cs

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@@ -0,0 +1,10 @@
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

namespace Microsoft.Diagnostics.DataContractReader.Data;

[CdacType(nameof(DataType.ResolveHelperFrame))]
internal partial class ResolveHelperFrame : IData<ResolveHelperFrame>
{
 [Field] public TargetPointer TransitionBlockPtr { get; }
}

1 change: 1 addition & 0 deletions
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/DataType.cs

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Original file line numberDiff line numberDiff line change
Expand Up@@ -166,6 +166,7 @@ public enum DataType
 InlinedCallFrame,
 SoftwareExceptionFrame,
 FramedMethodFrame,
 ResolveHelperFrame,
Comment thread
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 FuncEvalFrame,
 ResumableFrame,
 FaultingExceptionFrame,
Expand Down

2 changes: 1 addition & 1 deletion
src/native/managed/cdac/tests/TestInfrastructure/TestPlaceholderTarget.cs

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Expand Up@@ -546,7 +546,7 @@ public override Target.TypeInfo GetTypeInfo(string typeName)
 public override bool TryGetTypeInfo(string typeName, out Target.TypeInfo info)
 => _typeInfoCache.TryGetValue(typeName, out info);

 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => throw new NotImplementedException();
 public override bool TryGetThreadContext(ulong threadId, uint contextFlags, Span<byte> bufferToFill) => false;

 public override Target.IDataCache ProcessedData => _dataCache;
 public override ContractRegistry Contracts => _contractRegistry;
Expand Down

103 changes: 102 additions & 1 deletion
src/native/managed/cdac/tests/UnitTests/MockDescriptors/MockDescriptors.Frame.cs

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Expand Up@@ -76,6 +76,22 @@ public ulong MethodDescPtr
 }
}

internal sealed class MockResolveHelperFrame : MockFrame
{
 private const string TransitionBlockPtrFieldName = "TransitionBlockPtr";

 public static Layout<MockResolveHelperFrame> CreateLayout(Layout<MockFrame> baseLayout)
 => new SequentialLayoutBuilder("ResolveHelperFrame", baseLayout.Architecture, baseLayout)
 .AddPointerField(TransitionBlockPtrFieldName)
 .Build<MockResolveHelperFrame>();

 public ulong TransitionBlockPtr
 {
 get => ReadPointerField(TransitionBlockPtrFieldName);
 set => WritePointerField(TransitionBlockPtrFieldName, value);
 }
}

internal sealed class MockFuncEvalFrame : MockFrame
{
 // Mirrors the cDAC FuncEvalFrame data class which only reads DebuggerEvalPtr.
Expand DownExpand Up@@ -142,6 +158,59 @@ public ulong TargetContextPtr
 }
}

internal sealed class MockTransitionBlock : TypedView
{
 private const string ReturnAddressFieldName = "ReturnAddress";
 private const string CalleeSavedRegistersFieldName = "CalleeSavedRegisters";
 private const string ArgumentRegistersFieldName = "ArgumentRegisters";
 private const string FirstGCRefMapSlotFieldName = "FirstGCRefMapSlot";

 public static Layout<MockTransitionBlock> CreateLayout(MockTarget.Architecture architecture, Layout<MockRegisterSet> calleeSavedRegistersLayout, Layout<MockRegisterSet> argumentRegistersLayout)
 => new SequentialLayoutBuilder("TransitionBlock", architecture)
 .AddPointerField(ReturnAddressFieldName)
 .AddField(CalleeSavedRegistersFieldName, calleeSavedRegistersLayout.Size)
 .AddField(ArgumentRegistersFieldName, argumentRegistersLayout.Size)
 .AddPointerField(FirstGCRefMapSlotFieldName)
 .Build<MockTransitionBlock>();

 public ulong ReturnAddress
 {
 get => ReadPointerField(ReturnAddressFieldName);
 set => WritePointerField(ReturnAddressFieldName, value);
 }

 public ulong CalleeSavedRegister
 {
 get => ReadPointerField(CalleeSavedRegistersFieldName);
 set => WritePointerField(CalleeSavedRegistersFieldName, value);
 }

 public ulong ArgumentRegister
 {
 get => ReadPointerField(ArgumentRegistersFieldName);
 set => WritePointerField(ArgumentRegistersFieldName, value);
 }
}

internal sealed class MockRegisterSet : TypedView
{
 public const string CalleeSavedRegisterName = "rbx";
 public const string ArgumentRegisterName = "rcx";
 public const string Arm64CalleeSavedRegisterName = "x19";
 public const string Arm64ArgumentRegisterName = "x0";

 public static Layout<MockRegisterSet> CreateLayout(MockTarget.Architecture architecture, string name)
 => new SequentialLayoutBuilder(name, architecture)
 .AddPointerField(name)
 .Build<MockRegisterSet>();

 public ulong Register
 {
 get => ReadPointerField(Layout.Name);
 set => WritePointerField(Layout.Name, value);
 }
}

/// <summary>
/// Helper for building a Frame chain in the mock target memory. The Frame chain is
/// terminated with the FRAME_TOP sentinel (~0 sized to the target pointer width).
Expand All@@ -168,6 +237,7 @@ internal sealed class MockFrameBuilder
 public const ulong InterpreterFrameIdentifierValue = 0x0001_F009;
 public const ulong HijackFrameIdentifierValue = 0x0001_F00A;
 public const ulong RedirectedThreadFrameIdentifierValue = 0x0001_F00B;
 public const ulong ResolveHelperFrameIdentifierValue = 0x0001_F00C;

 private readonly MockMemorySpace.Builder _builder;
 private readonly MockMemorySpace.BumpAllocator _allocator;
Expand All@@ -177,16 +247,25 @@ internal sealed class MockFrameBuilder
 public Layout<MockFrame> FrameLayout { get; }
 public Layout<MockInlinedCallFrame> InlinedCallFrameLayout { get; }
 public Layout<MockFramedMethodFrame> FramedMethodFrameLayout { get; }
 public Layout<MockResolveHelperFrame> ResolveHelperFrameLayout { get; }
 public Layout<MockFuncEvalFrame> FuncEvalFrameLayout { get; }
 public Layout<MockDebuggerEval> DebuggerEvalLayout { get; }
 public Layout<MockResumableFrame> ResumableFrameLayout { get; }
 public Layout<MockTransitionBlock> TransitionBlockLayout { get; }
 public Layout<MockRegisterSet> CalleeSavedRegistersLayout { get; }
 public Layout<MockRegisterSet> ArgumentRegistersLayout { get; }

 public MockFrameBuilder(MockMemorySpace.Builder builder)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd))
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange)
 public MockFrameBuilder(MockMemorySpace.Builder builder, string calleeSavedRegisterName, string argumentRegisterName)
 : this(builder, (DefaultAllocationRangeStart, DefaultAllocationRangeEnd), calleeSavedRegisterName, argumentRegisterName)
 {
 }

 public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End) allocationRange, string? calleeSavedRegisterName = null, string? argumentRegisterName = null)
 {
 _builder = builder;
 _helpers = builder.TargetTestHelpers;
Expand All@@ -196,9 +275,13 @@ public MockFrameBuilder(MockMemorySpace.Builder builder, (ulong Start, ulong End
 FrameLayout = MockFrame.CreateLayout(_helpers.Arch);
 InlinedCallFrameLayout = MockInlinedCallFrame.CreateLayout(FrameLayout);
 FramedMethodFrameLayout = MockFramedMethodFrame.CreateLayout(FrameLayout);
 ResolveHelperFrameLayout = MockResolveHelperFrame.CreateLayout(FrameLayout);
 FuncEvalFrameLayout = MockFuncEvalFrame.CreateLayout(FrameLayout);
 DebuggerEvalLayout = MockDebuggerEval.CreateLayout(_helpers.Arch);
 ResumableFrameLayout = MockResumableFrame.CreateLayout(FrameLayout);
 CalleeSavedRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, calleeSavedRegisterName ?? MockRegisterSet.CalleeSavedRegisterName);
 ArgumentRegistersLayout = MockRegisterSet.CreateLayout(_helpers.Arch, argumentRegisterName ?? MockRegisterSet.ArgumentRegisterName);
 TransitionBlockLayout = MockTransitionBlock.CreateLayout(_helpers.Arch, CalleeSavedRegistersLayout, ArgumentRegistersLayout);
 }

 public ulong FrameTopTerminator => _terminator;
Expand DownExpand Up@@ -239,6 +322,24 @@ public MockFramedMethodFrame AddFramedMethodFrame(ulong methodDescPtr)
 return frame;
 }

 public MockResolveHelperFrame AddResolveHelperFrame(ulong transitionBlockPtr)
 {
 MockResolveHelperFrame frame = ResolveHelperFrameLayout.Create(_allocator.Allocate((ulong)ResolveHelperFrameLayout.Size, "ResolveHelperFrame"));
 frame.Identifier = ResolveHelperFrameIdentifierValue;
 frame.Next = _terminator;
 frame.TransitionBlockPtr = transitionBlockPtr;
 return frame;
 }

 public MockTransitionBlock AddTransitionBlock(ulong returnAddress, ulong calleeSavedRegister, ulong argumentRegister)
 {
 MockTransitionBlock transitionBlock = TransitionBlockLayout.Create(_allocator.Allocate((ulong)TransitionBlockLayout.Size, "TransitionBlock"));
 transitionBlock.ReturnAddress = returnAddress;
 transitionBlock.CalleeSavedRegister = calleeSavedRegister;
 transitionBlock.ArgumentRegister = argumentRegister;
 return transitionBlock;
 }

 public MockResumableFrame AddRedirectedThreadFrame(ulong targetContextPtr)
 {
 MockResumableFrame frame = ResumableFrameLayout.Create(_allocator.Allocate((ulong)ResumableFrameLayout.Size, "RedirectedThreadFrame"));
Expand Down
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