[cDAC] Implement SetDebugState for cDAC

[barosiak]

Summary

Implement SetDebugState in the cDAC. Separates debugger-controlled thread state from ThreadStateNoConcurrency into a new Volatile field to avoid read-modify-write races, and exposes it through the Thread contract.

Changes

• Added DebuggerControlledThreadState enum with Volatile<> to native Thread class
• Migrated TSNC_DebuggerUserSuspend to the new enum
• Exposed through data descriptor and managed contract
• Implemented DacDbiImpl.SetDebugState with #if DEBUG legacy validation
• Updated Thread.md contract documentation
• Added parameterized tests for set/reset/idempotency

Test Results

16 new test runs across all architectures. Existing tests pass.

[Copilot]

Pull request overview

Implements cDAC-side support for debugger thread state updates by exposing Thread::m_StateNC through the Thread contract and wiring DacDbiImpl.SetDebugState to set/reset the debugger-suspend bit, with matching tests and contract docs.

Changes:

• Added StateNC to the native and managed thread data descriptors and documented the new contract dependency.
• Added ThreadStateNoConcurrency plus SetThreadState / ResetThreadState on the cDAC IThread contract and used them from DacDbiImpl.SetDebugState.
• Added contract-level unit tests for set/reset/idempotent behavior and updated Thread contract documentation.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/native/managed/cdac/tests/ThreadTests.cs	Adds contract-level tests for setting/resetting StateNC.
src/native/managed/cdac/tests/MockDescriptors/MockDescriptors.Thread.cs	Extends mock thread layout with StateNC.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/IDacDbiInterface.cs	Adds managed projection enum for debug thread state values.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs	Implements SetDebugState via the Thread contract.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Data/Thread.cs	Adds StateNC member for descriptor name binding.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Thread_1.cs	Implements SetThreadState / ResetThreadState and reuses cached thread type info.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/IThread.cs	Expands the public Thread contract with the new enum and mutating methods.
src/coreclr/vm/threads.h	Annotates native enum values as contract-dependent and exports StateNC offset.
src/coreclr/vm/datadescriptor/datadescriptor.inc	Publishes Thread.StateNC in the cDAC data descriptor.
docs/design/datacontracts/Thread.md	Documents the new enum, APIs, and descriptor dependency.

Comments suppressed due to low confidence (1)

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/Dbi/DacDbiImpl.cs:706

• SetDebugState adds new DacDbi behavior, but the PR only adds contract-level ThreadTests. This leaves the DacDbi layer untested for the behaviors this method owns (notably HRESULT mapping for invalid states and the end-to-end state change through the legacy-facing API). The cDAC test guidance in src/native/managed/cdac/tests/README.md:21-32 calls for API-implementation-level tests when adding a new wrapper method backed by an existing contract.

            Contracts.ThreadData threadData = _target.Contracts.Thread.GetThreadData(new TargetPointer(vmThread));
            if ((threadData.State & (Contracts.ThreadState.Stopped | Contracts.ThreadState.Unstarted | Contracts.ThreadState.Detached)) != 0)
                throw Marshal.GetExceptionForHR(CorDbgHResults.CORDBG_E_BAD_THREAD_STATE)!;

            *pRetVal = threadData.ExposedObjectHandle.Value;
        }
        catch (System.Exception ex)
        {
            hr = ex.HResult;
        }
#if DEBUG
        if (_legacy is not null)
        {
            ulong retValLocal;
            int hrLocal = _legacy.GetThreadObject(vmThread, &retValLocal);
            Debug.ValidateHResult(hr, hrLocal);
            if (hr == HResults.S_OK)
                Debug.Assert(*pRetVal == retValLocal, $"cDAC: {*pRetVal:x}, DAC: {retValLocal:x}");

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[Copilot]

Pull request overview

Copilot reviewed 17 out of 17 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 18 out of 18 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 18 out of 18 changed files in this pull request and generated 4 comments.