Big-endian fixes: PDB creation by ilasm

[uweigand]

• Fix byte order of debug directory fields

• Fix byte order of PDB stream data (PdbHeap::SetData)

[ghost]

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Issue Details

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• Fix byte order of debug directory fields

• Fix byte order of PDB stream data (PdbHeap::SetData)

Author:	uweigand
Assignees:	-
Labels:	area-ILTools-coreclr
Milestone:	-

[uweigand]

CC @BruceForstall

Yet more endian issues in ilasm, this time when creating debug info / PDB files. The first problem is that the members of the DebugDirectory in the main .DLL need to be properly byte-swapped. The second problem is that when defining the PDB stream data, fields need to be swapped as well (in PdbHeap::SetData in md). The rest of the PDB contents seem fine, they're emitted via the MiniMd mechanism that already handles byte order properly.

This bug currently causes source-build to fail on s390x with the latest .NET 6 code, because a PDB file for an assembly created via ilasm contains invalid data, and therefore illink.dll fails to generate an updated PDB when trimming the assembly, and because of that missing final PDB the packaging fails.

Therefore, it would be great if this fix could still make it into .NET 6, ideally RC2.

[JulieLeeMSFT]

CC @dotnet/jit-contrib PTAL. Community request to backport to .NET 6 RC2.

[BruceForstall]

/azp run runtime-coreclr ilasm

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[BruceForstall]

LGTM

[BruceForstall]

The failures are #58481

[BruceForstall]

/backport to release/6.0

[github-actions]

Started backporting to release/6.0: https://github.com/dotnet/runtime/actions/runs/1260093631

[BruceForstall]

/backport to release/6.0-rc2

[github-actions]

Started backporting to release/6.0-rc2: https://github.com/dotnet/runtime/actions/runs/1262715856