[release/8.0-staging] Fix Crossgen2 PDB generation (again) #96566
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mangod9
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davidwrighton
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jeffschwMSFT
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Jan 12, 2024
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@trylek Friendly reminder that Tuesday January 16th 4pm is the Code Complete deadline for the February Release. If all requirements are met, please merge your PR before that date and time to ensure this fix gets included in that Release. |
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Backport of #96518 to release/8.0-staging
/cc @trylek
Customer Impact
Lack of meaningful symbol information for Crossgen2-compiled assemblies. This is only relevant for profiler scenarios, Watson and debugging in general use IL PDB information in combination with a special debug section in the Crossgen2 PE executable (unrelated to PDBs) that can be used to map RVAs to IL offsets. In particular, we believe the following apps / components to be affected by this deficiency:
• AzureProfiler
• CPR (M365 service-wide profiling)
• DiagTrack
• PerfView
• Fleet Diagnostics / Viewing of Traces in Azure DiagSpaces
• VS PerfTrack (capture of profiles of VS in production)
Testing
Local verification of the fix using cvdump, standard lab testing. I have also tested this with PerfView but it turns out that PerfView currently doesn't fully support lookup of .ni.pdb files for manually built Crossgen2 assemblies, I have put up a WIP PR with the PerfView fix to implement this support that is currently open for design discussion:
microsoft/perfview#1973
Risk
Low - PDB information is a relatively niche scenario mostly exercised in PerfView; it certainly shouldn't affect production behavior of .NET 8 apps.
IMPORTANT: If this backport is for a servicing release, please verify that:
The PR target branch is
release/X.0-staging, notrelease/X.0.If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.