[cDAC] Implement IsValidObject for cDAC - #128457

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barosiak merged 6 commits into
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barosiak:barosiak/IsValidObject
May 22, 2026
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[cDAC] Implement IsValidObject for cDAC#128457
barosiak merged 6 commits into
dotnet:mainfrom
barosiak:barosiak/IsValidObject

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@barosiakbarosiak commented May 21, 2026•
edited by rcj1
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Summary

Implement IsValidObject in the cDAC.

Changes

  • Implemented DacDbiImpl.IsValidObject
  • Added ContinuationSingletonEEClass global pointer to datadescriptor.inc
  • Added GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1
  • Added parameterized tests for the new APIs

@barosiakbarosiak self-assigned this May 21, 2026
CopilotAI review requested due to automatic review settings May 21, 2026 18:23
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Pull request overview

This PR extends the cDAC runtime type system contract (and its tests/mocks) to support additional MethodTable/EEClass queries, then uses those APIs to implement DacDbiImpl.IsValidObject. It also adds a new CoreCLR cDAC global (ContinuationSingletonEEClass) to enable continuation subtype identification.

Changes:

  • Adds a new CoreCLR cDAC global pointer (ContinuationSingletonEEClass) and wires it into the managed reader contracts/tests.
  • Extends IRuntimeTypeSystem / RuntimeTypeSystem_1 with APIs to query EEClass pointers, canonical MethodTables, and continuation-without-metadata detection.
  • Implements Microsoft.Diagnostics.DataContractReader.Legacy.DacDbiImpl.IsValidObject using the cDAC contracts and adds new MethodTable tests.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file
FileDescription
src/native/managed/cdac/tests/MockDescriptors/MockDescriptors.RuntimeTypeSystem.csAdds mock global storage + setter for the continuation singleton EEClass pointer.
src/native/managed/cdac/tests/MethodTableTests.csAdds globals wiring and new theory tests for IsContinuationWithoutMetadata and IsCanonicalMethodTable.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.csImplements IsValidObject using cDAC contracts (replacing legacy fallback-only behavior).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.csReads new global and implements new RTS APIs (GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Constants.csAdds the new global name constant.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.csAdds new public contract members used by IsValidObject.
src/coreclr/vm/datadescriptor/datadescriptor.incExposes g_singletonContinuationEEClass via a new cDAC global pointer.
Comments suppressed due to low confidence (1)

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs:548

  • GetClassPointer is now a public IRuntimeTypeSystem API, but it doesn't guard against non-MethodTable TypeHandles (it indexes _methodTables[typeHandle.Address] unconditionally). Other public APIs in this type return TargetPointer.Null / 0 for non-MethodTable handles. Please add a typeHandle.IsMethodTable() check (and return TargetPointer.Null or throw ArgumentException consistently) to avoid KeyNotFound/undefined behavior when callers pass a TypeDesc handle.
 public TargetPointer GetClassPointer(TypeHandle typeHandle)
{
MethodTable methodTable = _methodTables[typeHandle.Address];
switch (MethodTableFlags_1.GetEEClassOrCanonMTBits(methodTable.EEClassOrCanonMT))
{

Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs Outdated
Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
This was referenced May 21, 2026
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barosiak requested a review from rcj1May 21, 2026 23:54
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Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs Outdated
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rcj1 commented May 22, 2026•
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Might want to have a dump test for this, see

runtime/src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiCCWDumpTests.cs

Line 31 in 30359c8

TargetPointerobjectAddress=Target.ReadPointer(handleData.Handle);

(test that all objects read from these handles are valid and that an object at some non-object address is not)

noahfalk
noahfalk reviewed May 22, 2026
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Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md Outdated
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 5 comments.

Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
Comment threadsrc/native/managed/cdac/tests/DumpTests/AsyncContinuationDumpTests.cs
Comment thread...icrosoft.Diagnostics.DataContractReader.Contracts/RuntimeTypeSystemHelpers/TypeValidation.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md Outdated
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Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.

Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md Outdated
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
@barosiak
barosiak enabled auto-merge (squash) May 22, 2026 20:18
@barosiak
barosiak merged commit 070886d into dotnet:mainMay 22, 2026
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@MichalStrehovsky

MichalStrehovsky commented May 25, 2026

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Not sure why the Build Analysis was green but the relevant test leg "runtime (Build linux-x64 checked CLR_Tools_Tests)" that runs the Microsoft.Diagnostics.DataContractReader.Tests had failures in both IsContinuationWithoutMetadata_ReturnsFalseWhenSingletonEEClassGlobalIsNull and ValidateContinuationMethodTablePointer.

This is now breaking CI in e.g. #127768.

@jjonescz

jjonescz commented May 25, 2026•
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Haven't seen that before but it looks like it's automatically trying to detect non-deterministic test failures? https://github.com/dotnet/runtime/runs/77478246586

At least I think it won't break merging of other PRs since Build Analysis will probably ignore those again...

image

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@jjonescz@MichalStrehovsky should be fixed in #128526

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@barosiak@rcj1@MichalStrehovsky@jjonescz@noahfalk@max-charlamb
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[cDAC] Implement IsValidObject for cDAC - #128457
Merged
barosiak merged 6 commits into
dotnet:mainfrom 
barosiak:barosiak/IsValidObject
May 22, 2026
Merged
[cDAC] Implement IsValidObject for cDAC#128457
barosiak merged 6 commits into
dotnet:mainfrom 
barosiak:barosiak/IsValidObject
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May 21, 2026•

edited by rcj1

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Summary
Implement IsValidObject in the cDAC.
Changes
  • Implemented DacDbiImpl.IsValidObject
  • Added ContinuationSingletonEEClass global pointer to datadescriptor.inc
  • Added GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1
  • Added parameterized tests for the new APIs
@barosiakbarosiak
self-assigned this
May 21, 2026
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review requested due to automatic review settings
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Pull request overview
This PR extends the cDAC runtime type system contract (and its tests/mocks) to support additional MethodTable/EEClass queries, then uses those APIs to implement DacDbiImpl.IsValidObject. It also adds a new CoreCLR cDAC global (ContinuationSingletonEEClass) to enable continuation subtype identification.
Changes:
  • Adds a new CoreCLR cDAC global pointer (ContinuationSingletonEEClass) and wires it into the managed reader contracts/tests.
  • Extends IRuntimeTypeSystem / RuntimeTypeSystem_1 with APIs to query EEClass pointers, canonical MethodTables, and continuation-without-metadata detection.
  • Implements Microsoft.Diagnostics.DataContractReader.Legacy.DacDbiImpl.IsValidObject using the cDAC contracts and adds new MethodTable tests.
Reviewed changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
src/native/managed/cdac/tests/MockDescriptors/MockDescriptors.RuntimeTypeSystem.csAdds mock global storage + setter for the continuation singleton EEClass pointer.
src/native/managed/cdac/tests/MethodTableTests.csAdds globals wiring and new theory tests for IsContinuationWithoutMetadata and IsCanonicalMethodTable.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.csImplements IsValidObject using cDAC contracts (replacing legacy fallback-only behavior).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.csReads new global and implements new RTS APIs (GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Constants.csAdds the new global name constant.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.csAdds new public contract members used by IsValidObject.
src/coreclr/vm/datadescriptor/datadescriptor.incExposes g_singletonContinuationEEClass via a new cDAC global pointer.
Comments suppressed due to low confidence (1)
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs:548
  • GetClassPointer is now a public IRuntimeTypeSystem API, but it doesn't guard against non-MethodTable TypeHandles (it indexes _methodTables[typeHandle.Address] unconditionally). Other public APIs in this type return TargetPointer.Null / 0 for non-MethodTable handles. Please add a typeHandle.IsMethodTable() check (and return TargetPointer.Null or throw ArgumentException consistently) to avoid KeyNotFound/undefined behavior when callers pass a TypeDesc handle.
 public TargetPointer GetClassPointer(TypeHandle typeHandle)
{
MethodTable methodTable = _methodTables[typeHandle.Address];
switch (MethodTableFlags_1.GetEEClassOrCanonMTBits(methodTable.EEClassOrCanonMT))
{

Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
Outdated

Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs

This was referenced May 21, 2026

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Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
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May 22, 2026•

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Might want to have a dump test for this, see 
runtime/src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiCCWDumpTests.cs

Line 31
in
30359c8
TargetPointerobjectAddress=Target.ReadPointer(handleData.Handle);


(test that all objects read from these handles are valid and that an object at some non-object address is not)
noahfalk
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May 22, 2026
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Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 5 comments.
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
Comment threadsrc/native/managed/cdac/tests/DumpTests/AsyncContinuationDumpTests.cs
Comment thread...icrosoft.Diagnostics.DataContractReader.Contracts/RuntimeTypeSystemHelpers/TypeValidation.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Outdated

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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.
Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Outdated

Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
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Not sure why the Build Analysis was green but the relevant test leg "runtime (Build linux-x64 checked CLR_Tools_Tests)" that runs the Microsoft.Diagnostics.DataContractReader.Tests had failures in both IsContinuationWithoutMetadata_ReturnsFalseWhenSingletonEEClassGlobalIsNull and ValidateContinuationMethodTablePointer.
This is now breaking CI in e.g. #127768.
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Haven't seen that before but it looks like it's automatically trying to detect non-deterministic test failures? https://github.com/dotnet/runtime/runs/77478246586
At least I think it won't break merging of other PRs since Build Analysis will probably ignore those again...
image
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@jjonescz@MichalStrehovsky should be fixed in #128526
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injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
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})();
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try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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[cDAC] Implement IsValidObject for cDAC - #128457
Merged
barosiak merged 6 commits into
dotnet:mainfrom 
barosiak:barosiak/IsValidObject
May 22, 2026
Merged
[cDAC] Implement IsValidObject for cDAC#128457
barosiak merged 6 commits into
dotnet:mainfrom 
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May 21, 2026•

edited by rcj1

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Summary
Implement IsValidObject in the cDAC.
Changes
  • Implemented DacDbiImpl.IsValidObject
  • Added ContinuationSingletonEEClass global pointer to datadescriptor.inc
  • Added GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1
  • Added parameterized tests for the new APIs
@barosiakbarosiak
self-assigned this
May 21, 2026
CopilotAI
review requested due to automatic review settings
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Pull request overview
This PR extends the cDAC runtime type system contract (and its tests/mocks) to support additional MethodTable/EEClass queries, then uses those APIs to implement DacDbiImpl.IsValidObject. It also adds a new CoreCLR cDAC global (ContinuationSingletonEEClass) to enable continuation subtype identification.
Changes:
  • Adds a new CoreCLR cDAC global pointer (ContinuationSingletonEEClass) and wires it into the managed reader contracts/tests.
  • Extends IRuntimeTypeSystem / RuntimeTypeSystem_1 with APIs to query EEClass pointers, canonical MethodTables, and continuation-without-metadata detection.
  • Implements Microsoft.Diagnostics.DataContractReader.Legacy.DacDbiImpl.IsValidObject using the cDAC contracts and adds new MethodTable tests.
Reviewed changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
src/native/managed/cdac/tests/MockDescriptors/MockDescriptors.RuntimeTypeSystem.csAdds mock global storage + setter for the continuation singleton EEClass pointer.
src/native/managed/cdac/tests/MethodTableTests.csAdds globals wiring and new theory tests for IsContinuationWithoutMetadata and IsCanonicalMethodTable.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.csImplements IsValidObject using cDAC contracts (replacing legacy fallback-only behavior).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.csReads new global and implements new RTS APIs (GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Constants.csAdds the new global name constant.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.csAdds new public contract members used by IsValidObject.
src/coreclr/vm/datadescriptor/datadescriptor.incExposes g_singletonContinuationEEClass via a new cDAC global pointer.
Comments suppressed due to low confidence (1)
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs:548
  • GetClassPointer is now a public IRuntimeTypeSystem API, but it doesn't guard against non-MethodTable TypeHandles (it indexes _methodTables[typeHandle.Address] unconditionally). Other public APIs in this type return TargetPointer.Null / 0 for non-MethodTable handles. Please add a typeHandle.IsMethodTable() check (and return TargetPointer.Null or throw ArgumentException consistently) to avoid KeyNotFound/undefined behavior when callers pass a TypeDesc handle.
 public TargetPointer GetClassPointer(TypeHandle typeHandle)
{
MethodTable methodTable = _methodTables[typeHandle.Address];
switch (MethodTableFlags_1.GetEEClassOrCanonMTBits(methodTable.EEClassOrCanonMT))
{

Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
Outdated

Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs

This was referenced May 21, 2026

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Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
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May 22, 2026•

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Might want to have a dump test for this, see 
runtime/src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiCCWDumpTests.cs

Line 31
in
30359c8
TargetPointerobjectAddress=Target.ReadPointer(handleData.Handle);


(test that all objects read from these handles are valid and that an object at some non-object address is not)
noahfalk
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Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 5 comments.
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
Comment threadsrc/native/managed/cdac/tests/DumpTests/AsyncContinuationDumpTests.cs
Comment thread...icrosoft.Diagnostics.DataContractReader.Contracts/RuntimeTypeSystemHelpers/TypeValidation.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.
Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Outdated

Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
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Not sure why the Build Analysis was green but the relevant test leg "runtime (Build linux-x64 checked CLR_Tools_Tests)" that runs the Microsoft.Diagnostics.DataContractReader.Tests had failures in both IsContinuationWithoutMetadata_ReturnsFalseWhenSingletonEEClassGlobalIsNull and ValidateContinuationMethodTablePointer.
This is now breaking CI in e.g. #127768.
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Haven't seen that before but it looks like it's automatically trying to detect non-deterministic test failures? https://github.com/dotnet/runtime/runs/77478246586
At least I think it won't break merging of other PRs since Build Analysis will probably ignore those again...
image
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@jjonescz@MichalStrehovsky should be fixed in #128526
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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[cDAC] Implement IsValidObject for cDAC - #128457
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barosiak:barosiak/IsValidObject
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[cDAC] Implement IsValidObject for cDAC#128457
barosiak merged 6 commits into
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barosiak:barosiak/IsValidObject
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May 21, 2026•

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Summary
Implement IsValidObject in the cDAC.
Changes
  • Implemented DacDbiImpl.IsValidObject
  • Added ContinuationSingletonEEClass global pointer to datadescriptor.inc
  • Added GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1
  • Added parameterized tests for the new APIs
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Pull request overview
This PR extends the cDAC runtime type system contract (and its tests/mocks) to support additional MethodTable/EEClass queries, then uses those APIs to implement DacDbiImpl.IsValidObject. It also adds a new CoreCLR cDAC global (ContinuationSingletonEEClass) to enable continuation subtype identification.
Changes:
  • Adds a new CoreCLR cDAC global pointer (ContinuationSingletonEEClass) and wires it into the managed reader contracts/tests.
  • Extends IRuntimeTypeSystem / RuntimeTypeSystem_1 with APIs to query EEClass pointers, canonical MethodTables, and continuation-without-metadata detection.
  • Implements Microsoft.Diagnostics.DataContractReader.Legacy.DacDbiImpl.IsValidObject using the cDAC contracts and adds new MethodTable tests.
Reviewed changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
src/native/managed/cdac/tests/MockDescriptors/MockDescriptors.RuntimeTypeSystem.csAdds mock global storage + setter for the continuation singleton EEClass pointer.
src/native/managed/cdac/tests/MethodTableTests.csAdds globals wiring and new theory tests for IsContinuationWithoutMetadata and IsCanonicalMethodTable.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.csImplements IsValidObject using cDAC contracts (replacing legacy fallback-only behavior).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.csReads new global and implements new RTS APIs (GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Constants.csAdds the new global name constant.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.csAdds new public contract members used by IsValidObject.
src/coreclr/vm/datadescriptor/datadescriptor.incExposes g_singletonContinuationEEClass via a new cDAC global pointer.
Comments suppressed due to low confidence (1)
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs:548
  • GetClassPointer is now a public IRuntimeTypeSystem API, but it doesn't guard against non-MethodTable TypeHandles (it indexes _methodTables[typeHandle.Address] unconditionally). Other public APIs in this type return TargetPointer.Null / 0 for non-MethodTable handles. Please add a typeHandle.IsMethodTable() check (and return TargetPointer.Null or throw ArgumentException consistently) to avoid KeyNotFound/undefined behavior when callers pass a TypeDesc handle.
 public TargetPointer GetClassPointer(TypeHandle typeHandle)
{
MethodTable methodTable = _methodTables[typeHandle.Address];
switch (MethodTableFlags_1.GetEEClassOrCanonMTBits(methodTable.EEClassOrCanonMT))
{

Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
Outdated

Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs

This was referenced May 21, 2026

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Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
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Might want to have a dump test for this, see 
runtime/src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiCCWDumpTests.cs

Line 31
in
30359c8
TargetPointerobjectAddress=Target.ReadPointer(handleData.Handle);


(test that all objects read from these handles are valid and that an object at some non-object address is not)
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Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 5 comments.
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
Comment threadsrc/native/managed/cdac/tests/DumpTests/AsyncContinuationDumpTests.cs
Comment thread...icrosoft.Diagnostics.DataContractReader.Contracts/RuntimeTypeSystemHelpers/TypeValidation.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.
Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Outdated

Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
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Not sure why the Build Analysis was green but the relevant test leg "runtime (Build linux-x64 checked CLR_Tools_Tests)" that runs the Microsoft.Diagnostics.DataContractReader.Tests had failures in both IsContinuationWithoutMetadata_ReturnsFalseWhenSingletonEEClassGlobalIsNull and ValidateContinuationMethodTablePointer.
This is now breaking CI in e.g. #127768.
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May 25, 2026•

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Haven't seen that before but it looks like it's automatically trying to detect non-deterministic test failures? https://github.com/dotnet/runtime/runs/77478246586
At least I think it won't break merging of other PRs since Build Analysis will probably ignore those again...
image
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@jjonescz@MichalStrehovsky should be fixed in #128526
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content
[cDAC] Implement IsValidObject for cDAC - #128457
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barosiak merged 6 commits into
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barosiak:barosiak/IsValidObject
May 22, 2026
Merged
[cDAC] Implement IsValidObject for cDAC#128457
barosiak merged 6 commits into
dotnet:mainfrom 
barosiak:barosiak/IsValidObject
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May 21, 2026•

edited by rcj1

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Summary
Implement IsValidObject in the cDAC.
Changes
  • Implemented DacDbiImpl.IsValidObject
  • Added ContinuationSingletonEEClass global pointer to datadescriptor.inc
  • Added GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1
  • Added parameterized tests for the new APIs
@barosiakbarosiak
self-assigned this
May 21, 2026
CopilotAI
review requested due to automatic review settings
May 21, 2026 18:23
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Pull request overview
This PR extends the cDAC runtime type system contract (and its tests/mocks) to support additional MethodTable/EEClass queries, then uses those APIs to implement DacDbiImpl.IsValidObject. It also adds a new CoreCLR cDAC global (ContinuationSingletonEEClass) to enable continuation subtype identification.
Changes:
  • Adds a new CoreCLR cDAC global pointer (ContinuationSingletonEEClass) and wires it into the managed reader contracts/tests.
  • Extends IRuntimeTypeSystem / RuntimeTypeSystem_1 with APIs to query EEClass pointers, canonical MethodTables, and continuation-without-metadata detection.
  • Implements Microsoft.Diagnostics.DataContractReader.Legacy.DacDbiImpl.IsValidObject using the cDAC contracts and adds new MethodTable tests.
Reviewed changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
src/native/managed/cdac/tests/MockDescriptors/MockDescriptors.RuntimeTypeSystem.csAdds mock global storage + setter for the continuation singleton EEClass pointer.
src/native/managed/cdac/tests/MethodTableTests.csAdds globals wiring and new theory tests for IsContinuationWithoutMetadata and IsCanonicalMethodTable.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.csImplements IsValidObject using cDAC contracts (replacing legacy fallback-only behavior).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.csReads new global and implements new RTS APIs (GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Constants.csAdds the new global name constant.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.csAdds new public contract members used by IsValidObject.
src/coreclr/vm/datadescriptor/datadescriptor.incExposes g_singletonContinuationEEClass via a new cDAC global pointer.
Comments suppressed due to low confidence (1)
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs:548
  • GetClassPointer is now a public IRuntimeTypeSystem API, but it doesn't guard against non-MethodTable TypeHandles (it indexes _methodTables[typeHandle.Address] unconditionally). Other public APIs in this type return TargetPointer.Null / 0 for non-MethodTable handles. Please add a typeHandle.IsMethodTable() check (and return TargetPointer.Null or throw ArgumentException consistently) to avoid KeyNotFound/undefined behavior when callers pass a TypeDesc handle.
 public TargetPointer GetClassPointer(TypeHandle typeHandle)
{
MethodTable methodTable = _methodTables[typeHandle.Address];
switch (MethodTableFlags_1.GetEEClassOrCanonMTBits(methodTable.EEClassOrCanonMT))
{

Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
Outdated

Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs

This was referenced May 21, 2026

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Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
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Might want to have a dump test for this, see 
runtime/src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiCCWDumpTests.cs

Line 31
in
30359c8
TargetPointerobjectAddress=Target.ReadPointer(handleData.Handle);


(test that all objects read from these handles are valid and that an object at some non-object address is not)
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Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 5 comments.
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
Comment threadsrc/native/managed/cdac/tests/DumpTests/AsyncContinuationDumpTests.cs
Comment thread...icrosoft.Diagnostics.DataContractReader.Contracts/RuntimeTypeSystemHelpers/TypeValidation.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.
Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Outdated

Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
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enabled auto-merge (squash)
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Not sure why the Build Analysis was green but the relevant test leg "runtime (Build linux-x64 checked CLR_Tools_Tests)" that runs the Microsoft.Diagnostics.DataContractReader.Tests had failures in both IsContinuationWithoutMetadata_ReturnsFalseWhenSingletonEEClassGlobalIsNull and ValidateContinuationMethodTablePointer.
This is now breaking CI in e.g. #127768.
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Haven't seen that before but it looks like it's automatically trying to detect non-deterministic test failures? https://github.com/dotnet/runtime/runs/77478246586
At least I think it won't break merging of other PRs since Build Analysis will probably ignore those again...
image
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@jjonescz@MichalStrehovsky should be fixed in #128526
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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[cDAC] Implement IsValidObject for cDAC - #128457
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barosiak:barosiak/IsValidObject
May 22, 2026
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[cDAC] Implement IsValidObject for cDAC#128457
barosiak merged 6 commits into
dotnet:mainfrom 
barosiak:barosiak/IsValidObject
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May 21, 2026•

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Summary
Implement IsValidObject in the cDAC.
Changes
  • Implemented DacDbiImpl.IsValidObject
  • Added ContinuationSingletonEEClass global pointer to datadescriptor.inc
  • Added GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1
  • Added parameterized tests for the new APIs
@barosiakbarosiak
self-assigned this
May 21, 2026
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Pull request overview
This PR extends the cDAC runtime type system contract (and its tests/mocks) to support additional MethodTable/EEClass queries, then uses those APIs to implement DacDbiImpl.IsValidObject. It also adds a new CoreCLR cDAC global (ContinuationSingletonEEClass) to enable continuation subtype identification.
Changes:
  • Adds a new CoreCLR cDAC global pointer (ContinuationSingletonEEClass) and wires it into the managed reader contracts/tests.
  • Extends IRuntimeTypeSystem / RuntimeTypeSystem_1 with APIs to query EEClass pointers, canonical MethodTables, and continuation-without-metadata detection.
  • Implements Microsoft.Diagnostics.DataContractReader.Legacy.DacDbiImpl.IsValidObject using the cDAC contracts and adds new MethodTable tests.
Reviewed changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
src/native/managed/cdac/tests/MockDescriptors/MockDescriptors.RuntimeTypeSystem.csAdds mock global storage + setter for the continuation singleton EEClass pointer.
src/native/managed/cdac/tests/MethodTableTests.csAdds globals wiring and new theory tests for IsContinuationWithoutMetadata and IsCanonicalMethodTable.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.csImplements IsValidObject using cDAC contracts (replacing legacy fallback-only behavior).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.csReads new global and implements new RTS APIs (GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Constants.csAdds the new global name constant.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.csAdds new public contract members used by IsValidObject.
src/coreclr/vm/datadescriptor/datadescriptor.incExposes g_singletonContinuationEEClass via a new cDAC global pointer.
Comments suppressed due to low confidence (1)
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs:548
  • GetClassPointer is now a public IRuntimeTypeSystem API, but it doesn't guard against non-MethodTable TypeHandles (it indexes _methodTables[typeHandle.Address] unconditionally). Other public APIs in this type return TargetPointer.Null / 0 for non-MethodTable handles. Please add a typeHandle.IsMethodTable() check (and return TargetPointer.Null or throw ArgumentException consistently) to avoid KeyNotFound/undefined behavior when callers pass a TypeDesc handle.
 public TargetPointer GetClassPointer(TypeHandle typeHandle)
{
MethodTable methodTable = _methodTables[typeHandle.Address];
switch (MethodTableFlags_1.GetEEClassOrCanonMTBits(methodTable.EEClassOrCanonMT))
{

Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
Outdated

Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs

This was referenced May 21, 2026

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Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
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May 22, 2026•

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Might want to have a dump test for this, see 
runtime/src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiCCWDumpTests.cs

Line 31
in
30359c8
TargetPointerobjectAddress=Target.ReadPointer(handleData.Handle);


(test that all objects read from these handles are valid and that an object at some non-object address is not)
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Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 5 comments.
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
Comment threadsrc/native/managed/cdac/tests/DumpTests/AsyncContinuationDumpTests.cs
Comment thread...icrosoft.Diagnostics.DataContractReader.Contracts/RuntimeTypeSystemHelpers/TypeValidation.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.
Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Outdated

Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
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Not sure why the Build Analysis was green but the relevant test leg "runtime (Build linux-x64 checked CLR_Tools_Tests)" that runs the Microsoft.Diagnostics.DataContractReader.Tests had failures in both IsContinuationWithoutMetadata_ReturnsFalseWhenSingletonEEClassGlobalIsNull and ValidateContinuationMethodTablePointer.
This is now breaking CI in e.g. #127768.
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Haven't seen that before but it looks like it's automatically trying to detect non-deterministic test failures? https://github.com/dotnet/runtime/runs/77478246586
At least I think it won't break merging of other PRs since Build Analysis will probably ignore those again...
image
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@jjonescz@MichalStrehovsky should be fixed in #128526
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
[cDAC] Implement IsValidObject for cDAC - #128457
Merged
barosiak merged 6 commits into
dotnet:mainfrom 
barosiak:barosiak/IsValidObject
May 22, 2026
Merged
[cDAC] Implement IsValidObject for cDAC#128457
barosiak merged 6 commits into
dotnet:mainfrom 
barosiak:barosiak/IsValidObject
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commented
May 21, 2026•

edited by rcj1

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Summary
Implement IsValidObject in the cDAC.
Changes
  • Implemented DacDbiImpl.IsValidObject
  • Added ContinuationSingletonEEClass global pointer to datadescriptor.inc
  • Added GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1
  • Added parameterized tests for the new APIs
@barosiakbarosiak
self-assigned this
May 21, 2026
CopilotAI
review requested due to automatic review settings
May 21, 2026 18:23
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Pull request overview
This PR extends the cDAC runtime type system contract (and its tests/mocks) to support additional MethodTable/EEClass queries, then uses those APIs to implement DacDbiImpl.IsValidObject. It also adds a new CoreCLR cDAC global (ContinuationSingletonEEClass) to enable continuation subtype identification.
Changes:
  • Adds a new CoreCLR cDAC global pointer (ContinuationSingletonEEClass) and wires it into the managed reader contracts/tests.
  • Extends IRuntimeTypeSystem / RuntimeTypeSystem_1 with APIs to query EEClass pointers, canonical MethodTables, and continuation-without-metadata detection.
  • Implements Microsoft.Diagnostics.DataContractReader.Legacy.DacDbiImpl.IsValidObject using the cDAC contracts and adds new MethodTable tests.
Reviewed changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
src/native/managed/cdac/tests/MockDescriptors/MockDescriptors.RuntimeTypeSystem.csAdds mock global storage + setter for the continuation singleton EEClass pointer.
src/native/managed/cdac/tests/MethodTableTests.csAdds globals wiring and new theory tests for IsContinuationWithoutMetadata and IsCanonicalMethodTable.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.csImplements IsValidObject using cDAC contracts (replacing legacy fallback-only behavior).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.csReads new global and implements new RTS APIs (GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Constants.csAdds the new global name constant.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.csAdds new public contract members used by IsValidObject.
src/coreclr/vm/datadescriptor/datadescriptor.incExposes g_singletonContinuationEEClass via a new cDAC global pointer.
Comments suppressed due to low confidence (1)
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs:548
  • GetClassPointer is now a public IRuntimeTypeSystem API, but it doesn't guard against non-MethodTable TypeHandles (it indexes _methodTables[typeHandle.Address] unconditionally). Other public APIs in this type return TargetPointer.Null / 0 for non-MethodTable handles. Please add a typeHandle.IsMethodTable() check (and return TargetPointer.Null or throw ArgumentException consistently) to avoid KeyNotFound/undefined behavior when callers pass a TypeDesc handle.
 public TargetPointer GetClassPointer(TypeHandle typeHandle)
{
MethodTable methodTable = _methodTables[typeHandle.Address];
switch (MethodTableFlags_1.GetEEClassOrCanonMTBits(methodTable.EEClassOrCanonMT))
{

Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
Outdated

Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs

This was referenced May 21, 2026

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Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
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May 22, 2026•

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Might want to have a dump test for this, see 
runtime/src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiCCWDumpTests.cs

Line 31
in
30359c8
TargetPointerobjectAddress=Target.ReadPointer(handleData.Handle);


(test that all objects read from these handles are valid and that an object at some non-object address is not)
noahfalk
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reviewed
May 22, 2026
View reviewed changes
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Outdated

Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 5 comments.
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
Comment threadsrc/native/managed/cdac/tests/DumpTests/AsyncContinuationDumpTests.cs
Comment thread...icrosoft.Diagnostics.DataContractReader.Contracts/RuntimeTypeSystemHelpers/TypeValidation.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.
Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Outdated

Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
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enabled auto-merge (squash)
May 22, 2026 20:18
@barosiak
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merged commit 070886d
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dotnet:mainMay 22, 2026

122 of 127 checks passed

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Not sure why the Build Analysis was green but the relevant test leg "runtime (Build linux-x64 checked CLR_Tools_Tests)" that runs the Microsoft.Diagnostics.DataContractReader.Tests had failures in both IsContinuationWithoutMetadata_ReturnsFalseWhenSingletonEEClassGlobalIsNull and ValidateContinuationMethodTablePointer.
This is now breaking CI in e.g. #127768.
@jjonescz
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May 25, 2026•

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Haven't seen that before but it looks like it's automatically trying to detect non-deterministic test failures? https://github.com/dotnet/runtime/runs/77478246586
At least I think it won't break merging of other PRs since Build Analysis will probably ignore those again...
image
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@jjonescz@MichalStrehovsky should be fixed in #128526
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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[cDAC] Implement IsValidObject for cDAC - #128457
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barosiak merged 6 commits into
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barosiak:barosiak/IsValidObject
May 22, 2026
Merged
[cDAC] Implement IsValidObject for cDAC#128457
barosiak merged 6 commits into
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barosiak:barosiak/IsValidObject
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edited by rcj1

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Summary
Implement IsValidObject in the cDAC.
Changes
  • Implemented DacDbiImpl.IsValidObject
  • Added ContinuationSingletonEEClass global pointer to datadescriptor.inc
  • Added GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1APIs to the IRuntimeTypeSystem contract and RuntimeTypeSystem_1
  • Added parameterized tests for the new APIs
@barosiakbarosiak
self-assigned this
May 21, 2026
CopilotAI
review requested due to automatic review settings
May 21, 2026 18:23
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Pull request overview
This PR extends the cDAC runtime type system contract (and its tests/mocks) to support additional MethodTable/EEClass queries, then uses those APIs to implement DacDbiImpl.IsValidObject. It also adds a new CoreCLR cDAC global (ContinuationSingletonEEClass) to enable continuation subtype identification.
Changes:
  • Adds a new CoreCLR cDAC global pointer (ContinuationSingletonEEClass) and wires it into the managed reader contracts/tests.
  • Extends IRuntimeTypeSystem / RuntimeTypeSystem_1 with APIs to query EEClass pointers, canonical MethodTables, and continuation-without-metadata detection.
  • Implements Microsoft.Diagnostics.DataContractReader.Legacy.DacDbiImpl.IsValidObject using the cDAC contracts and adds new MethodTable tests.
Reviewed changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.
Show a summary per file
FileDescription
src/native/managed/cdac/tests/MockDescriptors/MockDescriptors.RuntimeTypeSystem.csAdds mock global storage + setter for the continuation singleton EEClass pointer.
src/native/managed/cdac/tests/MethodTableTests.csAdds globals wiring and new theory tests for IsContinuationWithoutMetadata and IsCanonicalMethodTable.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.csImplements IsValidObject using cDAC contracts (replacing legacy fallback-only behavior).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.csReads new global and implements new RTS APIs (GetClassPointer, IsCanonicalMethodTable, IsContinuationWithoutMetadata).
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Constants.csAdds the new global name constant.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.csAdds new public contract members used by IsValidObject.
src/coreclr/vm/datadescriptor/datadescriptor.incExposes g_singletonContinuationEEClass via a new cDAC global pointer.
Comments suppressed due to low confidence (1)
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs:548
  • GetClassPointer is now a public IRuntimeTypeSystem API, but it doesn't guard against non-MethodTable TypeHandles (it indexes _methodTables[typeHandle.Address] unconditionally). Other public APIs in this type return TargetPointer.Null / 0 for non-MethodTable handles. Please add a typeHandle.IsMethodTable() check (and return TargetPointer.Null or throw ArgumentException consistently) to avoid KeyNotFound/undefined behavior when callers pass a TypeDesc handle.
 public TargetPointer GetClassPointer(TypeHandle typeHandle)
{
MethodTable methodTable = _methodTables[typeHandle.Address];
switch (MethodTableFlags_1.GetEEClassOrCanonMTBits(methodTable.EEClassOrCanonMT))
{

Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
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Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs

This was referenced May 21, 2026

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Comment threadsrc/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs
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May 22, 2026•

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Might want to have a dump test for this, see 
runtime/src/native/managed/cdac/tests/DumpTests/DacDbi/DacDbiCCWDumpTests.cs

Line 31
in
30359c8
TargetPointerobjectAddress=Target.ReadPointer(handleData.Handle);


(test that all objects read from these handles are valid and that an object at some non-object address is not)
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Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 5 comments.
Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
Comment threadsrc/native/managed/cdac/tests/DumpTests/AsyncContinuationDumpTests.cs
Comment thread...icrosoft.Diagnostics.DataContractReader.Contracts/RuntimeTypeSystemHelpers/TypeValidation.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Pull request overview
Copilot reviewed 12 out of 12 changed files in this pull request and generated 4 comments.
Comment thread...ged/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/RuntimeTypeSystem_1.cs
Comment thread...d/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IRuntimeTypeSystem.cs
Comment threaddocs/design/datacontracts/RuntimeTypeSystem.md
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Comment threadsrc/native/managed/cdac/tests/MethodTableTests.cs
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@MichalStrehovsky
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Not sure why the Build Analysis was green but the relevant test leg "runtime (Build linux-x64 checked CLR_Tools_Tests)" that runs the Microsoft.Diagnostics.DataContractReader.Tests had failures in both IsContinuationWithoutMetadata_ReturnsFalseWhenSingletonEEClassGlobalIsNull and ValidateContinuationMethodTablePointer.
This is now breaking CI in e.g. #127768.
@jjonescz
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May 25, 2026•

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Haven't seen that before but it looks like it's automatically trying to detect non-deterministic test failures? https://github.com/dotnet/runtime/runs/77478246586
At least I think it won't break merging of other PRs since Build Analysis will probably ignore those again...
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@jjonescz@MichalStrehovsky should be fixed in #128526
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