Implement CLRDataMethodDefinition IL extent APIs in cDAC

[Copilot]

Implements IL extent enumeration and representative entry-address lookup for CLRDataMethodDefinition, replacing legacy fallback behavior.

• Implementation

  • Adds StartEnumExtents, EnumExtent, EndEnumExtents, and GetRepresentativeEntryAddress.
  • Preserves legacy DAC semantics for tiny/fat IL headers and single-shot enumeration.

• Validation

  • Covers invalid arguments, missing IL, and tiny/extended-fat headers.

Note

This description was generated by GitHub Copilot.

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[Copilot]

Copilot's findings

Comments suppressed due to low confidence (1)

src/native/managed/cdac/tests/UnitTests/IXCLRDataProcessTests.cs:252

• The test currently writes the fat header CodeSize using the target endianness (arch.IsLittleEndian), but IL headers are fixed little-endian (ECMA-335) and the implementation should be reading via ReadLittleEndian. Encoding the header this way can let big-endian tests pass even if the production code is incorrectly using target-endian reads.

            secondHeader[codeSizeByteOffset] = FatCodeSize;

• Files reviewed: 4/4 changed files
• Comments generated: 1

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[Copilot]

Copilot's findings

Comments suppressed due to low confidence (2)

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/ClrDataMethodDefinition.cs:422

• StartEnumExtents dereferences handle before validating it. Other similar COM enumeration entrypoints (e.g., ClrDataMethodInstance.StartEnumExtents) explicitly check for null and throw ArgumentNullException to reliably return E_POINTER without relying on null-pointer deref behavior.

        try
        {
            *handle = 0;
            TargetPointer code = GetILExtentStart(out uint codeSize);
            if (code == TargetPointer.Null)

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/IXCLRData.cs:934

• This change introduces a new public enum and changes the public field type of ClrDataMethodDefinitionExtent.type from uint to CLRDataMethodDefinitionExtentType. That is a source-breaking public surface change for any consumers of the (packable) Legacy assembly. If this API is intended to be public, it should follow the repo’s public API approval process; otherwise consider keeping the field as uint (with a comment or helper cast) or making the enum/internal surface non-public.

public enum CLRDataMethodDefinitionExtentType : uint
{
    CLRDATA_METHDEF_IL,
}

public struct ClrDataMethodDefinitionExtent
{
    public ClrDataAddress startAddress;
    public ClrDataAddress endAddress;
    public uint enCVersion;
    public CLRDataMethodDefinitionExtentType type;
}

• Files reviewed: 8/8 changed files
• Comments generated: 2

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[noahfalk]

I don't think we normally check this for debug validation, it just controls whether the production code is allowed to fall back. (Same pattern in other DEBUG blocks below)

[Copilot]

Copilot's findings

Comments suppressed due to low confidence (1)

src/native/managed/cdac/Microsoft.Diagnostics.DataContractReader.Legacy/IXCLRData.cs:934

• This change introduces new public API surface in the Legacy COM projections (new public enum CLRDataMethodDefinitionExtentType and changing ClrDataMethodDefinitionExtent.type from uint to that enum). The PR description doesn’t link an api-approved issue as required for new public APIs. If this is intended to avoid API review, consider keeping the struct field as uint (matching the prior surface) and using an internal enum/consts for readability, or link the approved API issue.

public enum CLRDataMethodDefinitionExtentType : uint
{
    CLRDATA_METHDEF_IL,
}

public struct ClrDataMethodDefinitionExtent
{
    public ClrDataAddress startAddress;
    public ClrDataAddress endAddress;
    public uint enCVersion;
    public CLRDataMethodDefinitionExtentType type;
}

• Files reviewed: 8/8 changed files
• Comments generated: 1