Use CodeVersioning for EnC by rcj1 · Pull Request #130159 · dotnet/runtime

rcj1 · 2026-07-03T06:35:58Z

Implement existing runtime and cDAC functionality with EnC as a code version. Each subsequent edit corresponds to a single new ILCodeVersion with a single NativeCodeVersion.
EnC remains incompatible with ReJIT.
Added a Source field to ILCodeVersionNode to distinguish the sources.

dotnet-policy-service · 2026-07-03T06:37:34Z

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Copilot

Pull request overview

This PR extends the existing code-versioning infrastructure so Edit-and-Continue (EnC) edits are represented as explicit IL code versions (distinct from ReJIT), and updates DAC/cDAC and debugger plumbing to treat only true ReJIT versions as ReJIT.

Changes:

Adds a “source” discriminator for IL code versions (ReJIT vs EnC) plus an EnC version counter, and threads this through CoreCLR, data descriptors, and cDAC contracts.
Updates ReJIT enumeration / DAC-facing ReJIT APIs to exclude EnC code versions (and excludes the synthetic default version from ReJIT ID enumeration).
Adjusts IL retrieval paths in legacy cDAC/DAC DBI paths to read IL from the active EnC code version where appropriate; updates/extends unit tests and contract docs.

Show a summary per file

File	Description
src/native/managed/cdac/tests/UnitTests/ReJITTests.cs	Updates expected ReJIT ID enumeration behavior and mocks `ICodeVersions.IsReJIT`.
src/native/managed/cdac/tests/UnitTests/MockDescriptors/MockDescriptors.CodeVersions.cs	Extends mock IL code version node layout with `Source`/`EnCVersion`; updates builder helpers.
src/native/managed/cdac/tests/UnitTests/CodeVersionsTests.cs	Adds coverage asserting EnC/default versions are excluded from ReJIT detection and enumeration.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/SOSDacImpl.cs	Filters ReJIT-related legacy SOS DAC behaviors using `ICodeVersions.IsReJIT`.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs	Fetches IL from active EnC code version when available; filters IL code version node APIs to ReJIT only.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/ClrDataFrame.cs	Uses active EnC IL for local signature parsing when applicable.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/ILCodeVersionNode.cs	Adds `Source` and `EnCVersion` fields to the ILCodeVersionNode contract data type.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/CodeVersions_1.cs	Implements `ICodeVersions.IsReJIT` based on the new `ILCodeVersionNode.Source`.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/ICodeVersions.cs	Introduces `public CodeVersionSource` and new `ICodeVersions.IsReJIT` API.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/Extensions/IReJITExtensions.cs	Filters ReJIT ID enumeration to true ReJIT versions via `cv.IsReJIT`.
src/coreclr/vm/rejit.cpp	Tags configured ReJIT IL code versions with `CodeVersionSource::kReJIT`; filters ReJIT ID queries.
src/coreclr/vm/method.hpp	Makes EnC IL methods versionable via CodeVersionManager; enforces EnC/ReJIT mutual exclusion.
src/coreclr/vm/method.cpp	Returns active EnC IL from CodeVersionManager in `MethodDesc::GetILHeader`.
src/coreclr/vm/encee.cpp	Creates/activates EnC IL code versions via CodeVersionManager; records source and EnC version.
src/coreclr/vm/datadescriptor/datadescriptor.inc	Adds `ILCodeVersionNode.Source` and `ILCodeVersionNode.EnCVersion` to the CDAC descriptor.
src/coreclr/vm/codeversion.h	Adds `CodeVersionSource` enum and stores `Source`/`EnCVersion` on `ILCodeVersionNode`.
src/coreclr/vm/codeversion.cpp	Implements `ILCodeVersion::IsReJIT` / `GetEnCVersion`, plus node accessors/mutators.
src/coreclr/debug/ee/functioninfo.cpp	Treats only ReJIT (not EnC) explicit versions as “rejitted” for boundary mapping behavior.
src/coreclr/debug/ee/debugger.cpp	Updates debugger ReJIT-related checks to ignore EnC versions; tags created versions as ReJIT.
src/coreclr/debug/daccess/request.cpp	Filters DAC ReJIT data paths to only ReJIT IL code versions.
src/coreclr/debug/daccess/dacdbiimpl.cpp	Uses CodeVersionManager to resolve EnC versions and EnC IL in DBI helper paths.
docs/design/datacontracts/CodeVersions.md	Documents the new `CodeVersionSource`/`IsReJIT` concepts (but needs an `EnCVersion` row added).

Copilot's findings

Files reviewed: 22/22 changed files
Comments generated: 4

+    public MockILCodeVersionNode AddILCodeVersionNode(ulong versionId, uint rejitFlags, bool deoptimized = false, uint source = 1 /* CodeVersionSource.ReJIT */, ulong encVersion = 0)
    {


Copilot

Copilot's findings

Files reviewed: 23/23 changed files
Comments generated: 6

Copilot

Copilot's findings

Comments suppressed due to low confidence (1)

src/coreclr/debug/daccess/request.cpp:4693

GetPendingReJITID now rejects the active ILCodeVersion unless ilVersion.IsReJIT() is true. However newly-requested ReJIT versions start in kStateRequested with CodeVersionSource still kUnknown (it isn't set until later in ConfigureILCodeVersion), so pending ReJIT queries will incorrectly return E_INVALIDARG. Reorder the checks to treat kStateRequested as a ReJIT-pending version even before Source is populated, and only use IsReJIT() to reject non-requested non-ReJIT (e.g., EnC) versions.

    CodeVersionManager::LockHolder codeVersioningLockHolder;
    ILCodeVersion ilVersion = pCodeVersionManager->GetActiveILCodeVersion(pMD);
    if (ilVersion.IsNull() || !ilVersion.IsReJIT())
    {
        hr = E_INVALIDARG;
    }
    else if (ilVersion.GetRejitState() == RejitFlags::kStateRequested)
    {

Files reviewed: 24/24 changed files
Comments generated: 3

Copilot

Copilot's findings

Files reviewed: 25/25 changed files
Comments generated: 4

+public enum CodeVersionSource : uint
+{
+    Unknown = 0,
+    ReJIT = 1,
+    EnC = 2,
+}


            _codeVersionsAllocator.Allocate((ulong)ILCodeVersioningStateLayout.Size, "ILCodeVersioningState"));

-    public MockILCodeVersionNode AddILCodeVersionNode(ulong versionId, uint rejitFlags, bool deoptimized = false, ulong ilAddress = 0)
+    public MockILCodeVersionNode AddILCodeVersionNode(ulong versionId, uint rejitFlags, bool deoptimized = false, uint source = 1 /* CodeVersionSource.ReJIT */, ulong encVersion = 0, ulong ilAddress = 0)


+| ILCodeVersionNode | Source | a `CodeVersionSource` value indicating what produced this version (ReJIT, EnC, or unknown) |
 | ILCodeVersionNode | InstrumentedILMap | Embedded `InstrumentedILOffsetMapping` describing the instrumented IL offset mapping |


+{
+    if (!ilCodeVersionHandle.IsExplicit)
+        return false;
+    return // node Source is ReJIT


jkotas · 2026-07-05T14:44:47Z

    Module *pModule = GetModule();

+#ifdef FEATURE_CODE_VERSIONING
+    if (InEnCEnabledModule())


Should both EnC and ReJIT be on the same plan? Either keep using dynamic IL to track last IL for both. Or drop dynamic IL for both and use dynamic IL for reflection emit only.

ReJIT already uses the code version to store IL. It looks like we had just never captured ReJIT IL here. We probably should

I wouldn't expect this method to get called for ReJIT methods and with the other changes in this PR I wouldn't expect ENC to call it either now. Unless there is something I am missing I'd suggest reverting this part of the change.

Both ReJIT and ENC should be getting their IL from the ILCodeVersion now:

ILCodeVersion::GetIL VersionedPrepareCodeConfig::GetILHeader GetAndVerifyMetadataILHeader GetAndVerifyILHeader JitCompileCodeLockedEventWrapper JitCompileCode PrepareCode PublishVersionableCodeIfNecessary DoPrestub

That VersionedPrepareCodeConfig is a derived type of PrepareCodeConfig that we use whenever compiling a non-default version of the code. The code in PublishVersionableCodeIfNecessary should detect the non-default version and use it.

There are some other callers where I can't rule it out being called on an EnC method: for example, GetAndVerifyMetadataILHeader

All calls to GetAndVerifyMetadataILHeader for a non-default version of a method are supposed to be using VersionedPrepareCodeConfig as the 'pConfig' argument which directs them down the code path I mentioned above and they don't get here. Do you see a path where VersionedPrepareCodeConfig won't be used for a non-default code version?

There is also MethodDescGetILHeader and the various callers on the DAC side (task.cpp, stack.cpp).

Ideally now that we have represented ENC code with explicit ILCodeVersions we should also only use version-aware handling of the IL. This ensures code paths get the IL that corresponds to particular version of the code they are introspecting as opposed to guessing that the default version or the latest version happens to be the right one. If that is a lot of work I don't mind if you include a comment saying the conversion is incomplete and assuming the caller wants the most recent ENC version is probably no worse than the behavior was in the past. However if we want to complete the conversion we should eliminate any code paths that call MethodDesc::GetILHeader() on non-default code versions.

For the MethodDescGetILHeader you mentioned the call path is:

-> Compiler::compCompile()
-> Compiler::eeGetVars()
-> ICorJitInfo::getVars / CEECodeGenInfo::getVars()
-> g_pDebugInterface->getVars(...)
-> Debugger::getVars(...)
-> g_pEEInterface->MethodDescGetILHeader(md)
-> MethodDesc::GetILHeader()

CEECodeGenInfo::getVars has access to the m_ILHeader for the exact version of the code being compiled so it could pass that along to Debugger::getVars() rather than having Debugger do a separate non-version-aware lookup.

noahfalk

This looked pretty good to me, a few suggestions inline.

noahfalk · 2026-07-07T20:37:22Z


    EX_TRY
    {
+        ReJITID ilCodeVersionId = 0;


I'd add a comment in the code here explaining that this behavior retains compatibility with how we reported ENC updates in the past (ie not giving them unique IL code version IDs) but that we should be open to reconsidering the behavior in the future. I think the current behavior represents natural evolution and no scenario that cared about it rather than any intentional design goal that ENC versions should be reported differently than ReJIT versions.

noahfalk · 2026-07-08T07:15:19Z

    Module *pModule = GetModule();

+#ifdef FEATURE_CODE_VERSIONING
+    if (InEnCEnabledModule())


I wouldn't expect this method to get called for ReJIT methods and with the other changes in this PR I wouldn't expect ENC to call it either now. Unless there is something I am missing I'd suggest reverting this part of the change.

Both ReJIT and ENC should be getting their IL from the ILCodeVersion now:

ILCodeVersion::GetIL VersionedPrepareCodeConfig::GetILHeader GetAndVerifyMetadataILHeader GetAndVerifyILHeader JitCompileCodeLockedEventWrapper JitCompileCode PrepareCode PublishVersionableCodeIfNecessary DoPrestub

That VersionedPrepareCodeConfig is a derived type of PrepareCodeConfig that we use whenever compiling a non-default version of the code. The code in PublishVersionableCodeIfNecessary should detect the non-default version and use it.

noahfalk · 2026-07-08T09:11:46Z

    // We have asked the profiler about this method via ICorProfilerFunctionControl,
    // and have thus stored the IL and codegen flags the profiler specified.
    // [cDAC] [ReJIT]: Contract depends on this value.
    kStateActive = 0x00000002,


Please include a comment on kStateActive and on RejitFlags above noting that despite the 'Rejit' name we also use RejitFlags::kStateActive for ENC methods which always have their IL populated in advance.

max-charlamb · 2026-07-08T20:27:16Z

+    if (pMD->IsAsyncThunkMethod())
+    {
+        pMD = pMD->GetAsyncVariantNoCreate();
+    }


What if the method was actually an ordinary method with the thunk version being async? GetAsyncVariantNoCreate always gives the async version even if it is the thunk.

Would we want something like:

if (pMD->IsAsyncThunkMethod()) { // The thunk delegates to the "other" variant which has the real IL body. pMD = pMD->IsAsyncVariantMethod() ? pMD->GetOrdinaryVariantNoCreate() // Async thunk → real IL is on Ordinary : pMD->GetAsyncVariantNoCreate(); // Ordinary thunk → real IL is on Async }

rcj1 added 2 commits July 2, 2026 22:35

use code versioning for EnC

b7b39ad

cdac updates

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Copilot AI review requested due to automatic review settings July 3, 2026 06:35

github-actions Bot added the area-Diagnostics-coreclr label Jul 3, 2026

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merge

f07a58c

fixes and adjust feature flag

e83c444

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fix ifdef

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rcj1 marked this pull request as ready for review July 4, 2026 16:00

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Comment thread src/coreclr/debug/daccess/dacdbiimpl.cpp

Comment thread ...anaged/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/ICodeVersions.cs

Comment thread src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/SOSDacImpl.cs

rcj1 added 2 commits July 4, 2026 09:16

update eventtrace

573b352

copilot review

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jkotas reviewed Jul 5, 2026

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jkotas requested a review from noahfalk July 5, 2026 14:48

noahfalk reviewed Jul 8, 2026

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rcj1 changed the title ~~[WIP] Use CodeVersioning for EnC~~ Use CodeVersioning for EnC Jul 8, 2026

max-charlamb reviewed Jul 8, 2026

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		public MockILCodeVersionNode AddILCodeVersionNode(ulong versionId, uint rejitFlags, bool deoptimized = false, uint source = 1 /* CodeVersionSource.ReJIT */, ulong encVersion = 0)
		{

		\| ILCodeVersionNode \| Source \| a `CodeVersionSource` value indicating what produced this version (ReJIT, EnC, or unknown) \|
		\| ILCodeVersionNode \| InstrumentedILMap \| Embedded `InstrumentedILOffsetMapping` describing the instrumented IL offset mapping \|

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rcj1 commented Jul 3, 2026

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max-charlamb Jul 8, 2026 •

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