[cDAC] Implement SetJITCompilerFlags for cDAC

[barosiak]

 Summary

Implement SetJITCompilerFlags on IXCLRDataModule2 in the cDAC.

 Changes

• ClrDataModule.cs - SetJITCompilerFlags implementation
• ILoader.cs / Loader_1.cs - added GetDebuggerInfoBits and SetDebuggerInfoBits contract methods with direct target memory read/write
• IXCLRData.cs - added DebuggerAssemblyControlFlags enum mirroring cordbpriv.h
• Tests - new tests covering get/set/flag-preservation

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[Copilot]

Pull request overview

Implements IXCLRDataModule2.SetJITCompilerFlags for the managed cDAC by wiring it to the Loader contract’s module transient-flag debugger bits, adding the necessary contract surface and tests to validate read/write behavior.

Changes:

• Implement IXCLRDataModule2.SetJITCompilerFlags in ClrDataModule by updating module debugger control bits via ILoader.
• Extend ILoader/Loader_1 with GetDebuggerInfoBits and SetDebuggerInfoBits, and document the new contract surface/constants.
• Update cDAC test infrastructure to support target-memory writes and add Loader tests for debugger-bit get/set and flag preservation.

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/ClrDataModule.cs	Implements SetJITCompilerFlags using Loader debugger-info bits.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/IXCLRData.cs	Adds managed DebuggerAssemblyControlFlags enum mirroring cordbpriv.h.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Abstractions/Contracts/ILoader.cs	Adds GetDebuggerInfoBits / SetDebuggerInfoBits to the Loader contract.
src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Contracts/Contracts/Loader_1.cs	Implements debugger-info bit get/set by reading/writing Module::Flags.
src/native/managed/cdac/tests/TestPlaceholderTarget.cs	Adds write-capable target support for tests.
src/native/managed/cdac/tests/MockDescriptors/MockDescriptors.Loader.cs	Allows initializing module transient flags in mocks.
src/native/managed/cdac/tests/LoaderTests.cs	Adds new tests for debugger-info bit behavior.
docs/design/datacontracts/Loader.md	Documents new Loader contract methods and constants.
src/coreclr/vm/ceeload.h	Notes cDAC Loader contract dependency on debugger-info mask/shift constants.
src/coreclr/inc/cordbpriv.h	Adds explicit comment that cDAC depends on flag values.

[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 2 comments.

[Copilot]

IXCLRDataModule2.SetJITCompilerFlags is now implemented, but there doesn’t appear to be any unit/integration test that exercises this COM entrypoint (argument validation and the expected updates to Module::m_dwTransientFlags via Loader.Get/SetDebuggerInfoBits). Adding a focused test that constructs a ClrDataModule over a mock Module, calls SetJITCompilerFlags with both supported values (and an invalid value), and then asserts the shifted debugger bits in target memory would help prevent regressions.

Suggested change

	int hr = HResults.S_OK;
	try
	{
	if ((flags != CORDEBUG_JIT_DEFAULT) && (flags != CORDEBUG_JIT_DISABLE_OPTIMIZATION))
	throw new ArgumentException();
	if ((flags != CORDEBUG_JIT_DEFAULT) && (flags != CORDEBUG_JIT_DISABLE_OPTIMIZATION))
	{
	return HResults.E_INVALIDARG;
	}
	int hr = HResults.S_OK;
	try
	{

[Copilot]

The SetDebuggerInfoBits pseudocode writes (newBits << DebuggerInfoShift) without masking to the available bit-range, but the contract implementation masks newBits to (DebuggerInfoMask >> DebuggerInfoShift) before shifting. Please update the documentation snippet to reflect the masking behavior so callers don’t assume higher bits will be preserved/written.

Suggested change

	uint updated = (currentFlags & ~DebuggerInfoMask) | (newBits << DebuggerInfoShift);
	uint updated = (currentFlags & ~DebuggerInfoMask) | ((newBits & (DebuggerInfoMask >> DebuggerInfoShift)) << DebuggerInfoShift);