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[cDAC] Implement DacDbi GetNativeCodeInfo / GetNativeCodeInfoForAddr #128338

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352ebcc
[cDAC] Implement DacDbi GetNativeCodeInfo / GetNativeCodeInfoForAddr
rcj1 May 15, 2026
794e87e
Update IDacDbiInterface.cs
rcj1 May 18, 2026
1a185ec
Apply suggestions from code review
rcj1 May 18, 2026
51fe617
Potential fix for pull request finding
rcj1 May 18, 2026
109f48f
ccr
rcj1 May 18, 2026
efc62f0
Add EnC unit tests for cDAC DacDbi native code APIs
Copilot May 18, 2026
7f0ded6
fix buidl break
rcj1 May 18, 2026
a948fbc
Add EnC contract unit tests
Copilot May 18, 2026
5d7dd6f
Refine EnC contract test names
Copilot May 18, 2026
dfaa609
Polish EnC contract unit test scaffolding
Copilot May 18, 2026
575085a
Rename EnC contract tests for clarity
Copilot May 18, 2026
e7644f1
Tidy EnC unit test naming
Copilot May 18, 2026
2b2c1a8
Clarify EnC unit test locals
Copilot May 18, 2026
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89 changes: 89 additions & 0 deletions docs/design/datacontracts/EnC.md
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@@ -0,0 +1,89 @@
# Contract EnC

This contract reports Edit and Continue (EnC) function version numbers for jitted
managed methods. EnC function versions are 1-based monotonically increasing counters
that the runtime assigns to each `EnC`-emitted instance of a method body.

## APIs of contract

``` csharp
// Returns the latest EnC version number associated with the method identified by
// (module, methodDef). If no EnC-jitted instance exists for that method, returns
// the default EnC function version (1).
TargetNUInt GetLatestEnCVersion(TargetPointer module, uint methodDef);

// Returns the EnC version number for the specific jitted instance of the method
// identified by (module, methodDef) whose hot region starts at the given native
// code address. If no matching jitted instance exists (for example, the method
// was never EnC-edited), returns the default EnC function version (1).
TargetNUInt GetEnCVersion(TargetPointer module, uint methodDef, TargetCodePointer nativeCodeAddress);
```

## Version 1

Data descriptors used:
| Data Descriptor Name | Field | Type | Purpose |
| --- | --- | --- | --- |
| `Module` | `EnCDataList` | nuint | Head of the singly linked list of `EnCData` entries for jitted EnC-versioned methods in this module |
| `EnCData` | `AddrOfCode` | nuint | Native code start (TADDR) for the jitted instance |
| `EnCData` | `Token` | uint32 | `mdMethodDef` token of the method |
| `EnCData` | `EnCVersion` | nuint | EnC function version number for this jitted instance |
| `EnCData` | `Next` | nuint | Next entry in the module's `EnCData` list, or null |

Global variables used:
| Global Name | Type | Purpose |
| --- | --- | --- |
| `CorDBDefaultEnCFunctionVersion` | nuint | Default EnC function version reported for methods that have never been EnC-edited (matches `CorDB_DEFAULT_ENC_FUNCTION_VERSION` in `src/coreclr/inc/cordbpriv.h`) |

Contracts used: none

``` csharp
// Returns the address of the first EnCData entry on module's EnCDataList whose Token
// matches methodDef and (when addrOrZero is non-null) whose AddrOfCode matches
// addrOrZero. Returns TargetPointer.Null if no entry matches.
TargetPointer FindEnCDataEntry(TargetPointer module, uint methodDef,
TargetPointer addrOrZero)
{
TargetPointer cur = _target.ReadPointer(module + /* Module::EnCDataList offset */);
while (cur != TargetPointer.Null)
{
uint token = _target.Read<uint>(cur + /* EnCData::Token offset */);
TargetPointer addrOfCode = _target.ReadPointer(cur + /* EnCData::AddrOfCode offset */);
if (token == methodDef &&
(addrOrZero == TargetPointer.Null || addrOfCode == addrOrZero))
{
return cur;
}
cur = _target.ReadPointer(cur + /* EnCData::Next offset */);
}
return TargetPointer.Null;
}
```

``` csharp
TargetNUInt GetLatestEnCVersion(TargetPointer module, uint methodDef)
{
TargetPointer entry = FindEnCDataEntry(module, methodDef, TargetPointer.Null);
if (entry == TargetPointer.Null)
return new TargetNUInt(/* CorDBDefaultEnCFunctionVersion global */);

return _target.ReadNUInt(entry + /* EnCData::EnCVersion offset */);
}
```

``` csharp
TargetNUInt GetEnCVersion(TargetPointer module, uint methodDef,
TargetCodePointer nativeCodeAddress)
{
if (nativeCodeAddress.Value == 0)
return new TargetNUInt(/* CorDBDefaultEnCFunctionVersion global */);

TargetPointer entry = FindEnCDataEntry(module, methodDef,
new TargetPointer(nativeCodeAddress.Value));
if (entry == TargetPointer.Null)
return new TargetNUInt(/* CorDBDefaultEnCFunctionVersion global */);

return _target.ReadNUInt(entry + /* EnCData::EnCVersion offset */);
}
```

11 changes: 11 additions & 0 deletions docs/design/datacontracts/Loader.md
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Expand Up @@ -103,6 +103,7 @@ TargetPointer GetILBase(ModuleHandle handle);
TargetPointer GetAssemblyLoadContext(ModuleHandle handle);
ModuleLookupTables GetLookupTables(ModuleHandle handle);
TargetPointer GetModuleLookupMapElement(TargetPointer table, uint token, out TargetNUInt flags);
TargetPointer LookupMemberRefAsMethod(ModuleHandle handle, uint memberRefToken);
IEnumerable<(TargetPointer, uint)> EnumerateModuleLookupMap(TargetPointer table);
bool IsCollectible(ModuleHandle handle);
bool IsDynamic(ModuleHandle handle);
Expand Down Expand Up @@ -254,6 +255,7 @@ enum ClrModifiableAssemblies : uint
| `MaxWebcilSections` | ushort | Maximum number of COFF sections supported in a Webcil image (must stay in sync with native `WEBCIL_MAX_SECTIONS`) | `16` |
| `DebuggerInfoMask` | uint | Mask for the debugger info bits within the Module's transient flags | `0x0000FC00` |
| `DebuggerInfoShift` | int | Bit shift for the debugger info bits within the Module's transient flags | `10` |
| `IS_FIELD_MEMBER_REF` | TADDR (target pointer-sized unsigned int) | Flag on `MemberRefToDescMap` entries indicating the entry is a FieldDesc, not a MethodDesc | `0x00000002` |
| `DEBUGGER_ALLOW_JIT_OPTS_PRIV` | uint | Debugger allows JIT optimizations (shifted in transient flags) | `0x00000800` |

Contracts used:
Expand Down Expand Up @@ -717,6 +719,15 @@ TargetPointer GetModuleLookupMapElement(TargetPointer table, uint token, out Tar
return TargetPointer.Null;
}

// Returns the MethodDesc pointer for the given mdMemberRef token, or TargetPointer.Null
// if the entry is a FieldDesc (flagged with IS_FIELD_MEMBER_REF) or not present.
TargetPointer LookupMemberRefAsMethod(ModuleHandle handle, uint memberRefToken)
{
ModuleLookupTables tables = GetLookupTables(handle);
TargetPointer ptr = GetModuleLookupMapElement(tables.MemberRefToDesc, memberRefToken, out TargetNUInt flags);
return (flags.Value & /* IS_FIELD_MEMBER_REF */) != 0 ? TargetPointer.Null : ptr;
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}

IEnumerable<(TargetPointer, uint)> EnumerateModuleLookupMap(TargetPointer table)
{
Data.ModuleLookupMap lookupMap = new Data.ModuleLookupMap(table);
Expand Down
47 changes: 45 additions & 2 deletions docs/design/datacontracts/RuntimeTypeSystem.md
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Expand Up @@ -244,6 +244,10 @@ partial interface IRuntimeTypeSystem : IContract
// Return true if the method is an async thunk method.
public virtual bool IsAsyncThunkMethod(MethodDescHandle methodDesc);

// Return the async variant MethodDesc for the given method, or null if not found.
// Mirrors the no-create path of native MethodDesc::GetAsyncVariantNoCreate.
public virtual MethodDescHandle? GetAsyncVariant(MethodDescHandle methodDesc);

// Return true if the method is a wrapper stub (unboxing or instantiating).
public virtual bool IsWrapperStub(MethodDescHandle methodDesc);

Expand Down Expand Up @@ -1212,8 +1216,11 @@ And the following enumeration definitions
[Flags]
internal enum AsyncMethodFlags : uint
{
None = 0,
Thunk = 16,
None = 0x0,
AsyncCall = 0x1,
IsAsyncVariant = 0x4,
Thunk = 0x10,
ReturnDroppingThunk = 0x20,
}

[Flags]
Expand Down Expand Up @@ -1698,6 +1705,42 @@ Determining if a method is a wrapper stub (unboxing or instantiating):
}
```

Resolving the async variant of an async thunk method (no-create):

```csharp
// Helper: matches native MatchesAsyncVariantLookup(AsyncVariantLookup::Async).
private bool IsAsyncVariantMethod(MethodDesc md)
{
if (!md.HasAsyncMethodData)
return false;

Data.AsyncMethodData asyncData = // Read AsyncMethodData from the async method data optional slot
AsyncMethodFlags flags = (AsyncMethodFlags)asyncData.Flags;
return flags.HasFlag(AsyncMethodFlags.IsAsyncVariant) && !flags.HasFlag(AsyncMethodFlags.ReturnDroppingThunk);
}

public MethodDescHandle? GetAsyncVariant(MethodDescHandle methodDescHandle)
{
MethodDesc md = _methodDescs[methodDescHandle.Address];
uint token = md.Token;
TypeHandle typeHandle = GetTypeHandle(GetMethodTable(methodDescHandle));

// For typical method definitions (non-generic or generic-with-formal-vars), native's
// FindOrCreateAssociatedMethodDesc returns the result of MethodTable::GetParallelMethodDesc
// directly. The canonical MethodTable holds the chunk of sibling MethodDescs that share
// a token; one of them carries the async-variant flag combination.
TypeHandle canonMT = GetTypeHandle(GetCanonicalMethodTable(typeHandle));
foreach (MethodDescHandle candidate in GetIntroducedMethods(canonMT))
{
MethodDesc candidateMd = _methodDescs[candidate.Address];
if (candidateMd.Token == token && IsAsyncVariantMethod(candidateMd))
return candidate;
}

return null;
}
```

Extracting a pointer to the `MethodDescVersioningState` data for a given method

```csharp
Expand Down
69 changes: 20 additions & 49 deletions src/coreclr/debug/daccess/dacdbiimpl.cpp
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Expand Up @@ -1255,8 +1255,7 @@ HRESULT STDMETHODCALLTYPE DacDbiInterfaceImpl::GetNativeCodeInfo(VMPTR_Assembly
if (pCodeInfo->m_rgCodeRegions[kHot].pAddress != (CORDB_ADDRESS)NULL)
{
pCodeInfo->isInstantiatedGeneric = pMethodDesc->HasClassOrMethodInstantiation();
LookupEnCVersions(pModule,
pCodeInfo->vmNativeCodeMethodDescToken,
LookupEnCVersions(pCodeInfo->vmNativeCodeMethodDescToken,
functionToken,
pCodeInfo->m_rgCodeRegions[kHot].pAddress,
&(pCodeInfo->encVersion));
Expand Down Expand Up @@ -1337,11 +1336,10 @@ HRESULT STDMETHODCALLTYPE DacDbiInterfaceImpl::GetNativeCodeInfoForAddr(CORDB_AD
pCodeInfo->isInstantiatedGeneric = pMethodDesc->HasClassOrMethodInstantiation();
pCodeInfo->vmNativeCodeMethodDescToken = vmMethodDesc;

SIZE_T unusedLatestEncVersion;
ULONG64 unusedLatestEncVersion;
Module * pModule = pMethodDesc->GetModule();
_ASSERTE(pModule != NULL);
LookupEnCVersions(pModule,
vmMethodDesc,
LookupEnCVersions(vmMethodDesc,
pMethodDesc->GetMemberDef(),
codeStartAddr,
&unusedLatestEncVersion, //unused by caller
Expand Down Expand Up @@ -5602,60 +5600,33 @@ HRESULT STDMETHODCALLTYPE DacDbiInterfaceImpl::GetPartialUserState(VMPTR_Thread
// thinking is that some of the RS data structures will remain, most likely in a reduced form.
//

void DacDbiInterfaceImpl::LookupEnCVersions(Module* pModule,
VMPTR_MethodDesc vmMethodDesc,
void DacDbiInterfaceImpl::LookupEnCVersions(VMPTR_MethodDesc vmMethodDesc,
mdMethodDef mdMethod,
CORDB_ADDRESS pNativeStartAddress,
SIZE_T * pLatestEnCVersion,
SIZE_T * pJittedInstanceEnCVersion /* = NULL */)
ULONG64 * pLatestEnCVersion,
ULONG64 * pJittedInstanceEnCVersion /* = NULL */)
{
MethodDesc * pMD = vmMethodDesc.GetDacPtr();

// make sure the vmMethodDesc and mdMethod match
_ASSERTE(pMD->GetMemberDef() == mdMethod);

MethodDesc * pMD = vmMethodDesc.GetDacPtr();
_ASSERTE(pLatestEnCVersion != NULL);

// @dbgtodo inspection - once we do EnC, stop using DMIs.
// If the method wasn't EnCed, DMIs may not exist. And since this is DAC, we can't create them.

// We may not have the memory for the DebuggerMethodInfos in a minidump.
// When dump debugging EnC information isn't very useful so just fallback
// to default version.
DebuggerMethodInfo * pDMI = NULL;
DebuggerJitInfo * pDJI = NULL;
EX_TRY_ALLOW_DATATARGET_MISSING_MEMORY
#ifndef FEATURE_METADATA_UPDATER
if (pJittedInstanceEnCVersion != NULL)
{
if (g_pDebugger != NULL)
{
pDMI = g_pDebugger->GetOrCreateMethodInfo(pModule, mdMethod);
if (pDMI != NULL)
{
pDJI = pDMI->FindJitInfo(pMD, CORDB_ADDRESS_TO_TADDR(pNativeStartAddress));
}
}
*pJittedInstanceEnCVersion = CorDB_DEFAULT_ENC_FUNCTION_VERSION;
}
EX_END_CATCH_ALLOW_DATATARGET_MISSING_MEMORY;
if (pDJI != NULL)
if (pLatestEnCVersion != NULL)
{
if (pJittedInstanceEnCVersion != NULL)
{
*pJittedInstanceEnCVersion = pDJI->m_encVersion;
}
*pLatestEnCVersion = pDMI->GetCurrentEnCVersion();
*pLatestEnCVersion = CorDB_DEFAULT_ENC_FUNCTION_VERSION;
}
else
#else
Module* pLoaderModule = pMD->GetLoaderModule();
PTR_EnCData pEnCData = pLoaderModule->FindEncData(mdMethod, CORDB_ADDRESS_TO_TADDR(pNativeStartAddress));
PTR_EnCData pLatestEncData = pLoaderModule->FindLatestEncData(mdMethod);
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if (pJittedInstanceEnCVersion != NULL)
{
// If we have no DMI/DJI, then we must never have EnCed. So we can use default EnC info
// Several cases where we don't have a DMI/DJI:
// - LCG methods
// - method was never "touched" by debugger. (DJIs are created lazily).
if (pJittedInstanceEnCVersion != NULL)
{
*pJittedInstanceEnCVersion = CorDB_DEFAULT_ENC_FUNCTION_VERSION;
}
*pLatestEnCVersion = CorDB_DEFAULT_ENC_FUNCTION_VERSION;
*pJittedInstanceEnCVersion = (pEnCData != NULL) ? pEnCData->encVersion : CorDB_DEFAULT_ENC_FUNCTION_VERSION;
}
*pLatestEnCVersion = (pLatestEncData != NULL) ? pLatestEncData->encVersion : CorDB_DEFAULT_ENC_FUNCTION_VERSION;
#endif // FEATURE_METADATA_UPDATER
}

// Get the address of the Debugger control block on the helper thread
Expand Down
7 changes: 3 additions & 4 deletions src/coreclr/debug/daccess/dacdbiimpl.h
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Expand Up @@ -883,12 +883,11 @@ class DacDbiInterfaceImpl :
BOOL UnwindRuntimeStackFrame(StackFrameIterator * pIter);

// Look up the EnC version number of a particular jitted instance of a managed method.
void LookupEnCVersions(Module* pModule,
VMPTR_MethodDesc vmMethodDesc,
void LookupEnCVersions(VMPTR_MethodDesc vmMethodDesc,
mdMethodDef mdMethod,
CORDB_ADDRESS pNativeStartAddress,
SIZE_T * pLatestEnCVersion,
SIZE_T * pJittedInstanceEnCVersion = NULL);
ULONG64 * pLatestEnCVersion,
ULONG64 * pJittedInstanceEnCVersion = NULL);

// @dbgtodo - This method should be removed once CordbFunctionBreakpoint and SetIP are moved OOP and
// no longer use nativeCodeJITInfoToken.
Expand Down
2 changes: 1 addition & 1 deletion src/coreclr/debug/di/divalue.cpp
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Expand Up @@ -2718,7 +2718,7 @@ HRESULT CordbObjectValue::GetFunctionHelper(ICorDebugFunction **ppFunction)
IfFailThrow(pDAC->GetNativeCodeInfo(functionAssembly, functionMethodDef, &nativeCodeForDelFunc));

RSSmartPtr<CordbModule> funcModule(GetAppDomain()->LookupOrCreateModule(functionAssembly));
func.Assign(funcModule->LookupOrCreateFunction(functionMethodDef, nativeCodeForDelFunc.encVersion));
func.Assign(funcModule->LookupOrCreateFunction(functionMethodDef, (SIZE_T)nativeCodeForDelFunc.encVersion));
}

*ppFunction = static_cast<ICorDebugFunction*> (func.GetValue());
Expand Down
4 changes: 2 additions & 2 deletions src/coreclr/debug/di/module.cpp
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Expand Up @@ -3902,7 +3902,7 @@ HRESULT CordbVariableHome::GetOffset(LONG *pOffset)
CordbNativeCode::CordbNativeCode(CordbFunction * pFunction,
const NativeCodeFunctionData * pJitData,
BOOL fIsInstantiatedGeneric)
: CordbCode(pFunction, (UINT_PTR)pJitData->m_rgCodeRegions[kHot].pAddress, pJitData->encVersion, FALSE),
: CordbCode(pFunction, (UINT_PTR)pJitData->m_rgCodeRegions[kHot].pAddress, (SIZE_T)pJitData->encVersion, FALSE),
m_vmNativeCodeMethodDescToken(pJitData->vmNativeCodeMethodDescToken),
m_fCodeAvailable(TRUE),
m_fIsInstantiatedGeneric(fIsInstantiatedGeneric != FALSE)
Expand Down Expand Up @@ -5093,7 +5093,7 @@ CordbNativeCode * CordbModule::LookupOrCreateNativeCode(mdMethodDef methodToken,
codeInfo.m_rgCodeRegions[kHot].cbSize));

// Lookup the function object that this code should be bound to
CordbFunction* pFunction = CordbModule::LookupOrCreateFunction(methodToken, codeInfo.encVersion);
CordbFunction* pFunction = CordbModule::LookupOrCreateFunction(methodToken, (SIZE_T)codeInfo.encVersion);
_ASSERTE(pFunction != NULL);

// There are bugs with the on-demand class load performed by CordbFunction in some cases. The old stack
Expand Down
11 changes: 11 additions & 0 deletions src/coreclr/debug/ee/functioninfo.cpp
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Expand Up @@ -1226,6 +1226,17 @@ void DebuggerJitInfo::Init(TADDR newAddress)
this->m_sizeOfCode = this->m_codeRegionInfo.getSizeOfTotalCode();

this->m_encVersion = this->m_methodInfo->GetCurrentEnCVersion();
#ifdef FEATURE_METADATA_UPDATER
if (this->m_encVersion != CorDB_DEFAULT_ENC_FUNCTION_VERSION)
{
Module* pModule = this->m_pLoaderModule;
EnCData* pEnCData = (EnCData*)(void*)pModule->GetLoaderAllocator()->GetLowFrequencyHeap()->AllocMem(S_SIZE_T(sizeof(EnCData)));
pEnCData->addrOfCode = (TADDR)this->m_addrOfCode;
pEnCData->token = this->m_methodInfo->m_token;
pEnCData->encVersion = this->m_encVersion;
pModule->AddEncData(pEnCData);
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Comment on lines 1228 to +1237

@rcj1 rcj1 May 18, 2026 •
edited
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good catch. Only possibly relevant in

runtime/src/coreclr/debug/di/divalue.cpp

Line 2748 in 3206a8e

HRESULT CordbObjectValue::GetFunction(ICorDebugFunction **ppFunction)
, but could return the latest jitted version as opposed to the latest version total. This is probably worth fixing

@github-actions github-actions Bot Jul 19, 2026

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AddEncData performs an unsynchronized push onto Module::m_pEnCDataList (pData->pNext = m_pEnCDataList; m_pEnCDataList = ... in ceeload.h), and DebuggerJitInfo::Init runs before the DJI is published under DebuggerDataLockHolder in CreateInitAndAddJitInfo (the _ASSERTE(!g_pDebugger->HasDebuggerDataLock()) above confirms no lock is held here). Two threads JITting EnC-versioned methods of the same module concurrently can therefore race on the list head. Additionally, if a DJI create races and the losing DJI is later deleted (DeleteInteropSafe), the EnCData node it already pushed here stays on the module list (LowFrequencyHeap alloc, never unlinked), and DeleteJitInfo likewise does not remove nodes. FindLatest/FindEncData tolerate duplicates so this is likely benign in practice, but please confirm the list mutation is safe against concurrent JIT and that leaked/duplicate nodes are acceptable — the previous code path relied on the already-locked DMI/DJI structures for this.

}
#endif // FEATURE_METADATA_UPDATER

this->InitFuncletAddress();

Expand Down
2 changes: 1 addition & 1 deletion src/coreclr/debug/inc/dacdbistructures.h
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Expand Up @@ -509,7 +509,7 @@ class MSLAYOUT NativeCodeFunctionData
VMPTR_MethodDesc vmNativeCodeMethodDescToken;

// EnC version number of the function
SIZE_T encVersion;
ULONG64 encVersion;
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};

//----------------------------------------------------------------------------------
Expand Down
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