ILC crashes on a test project with 1mln delegates and 1000 cctors

[MichalPetryka]

Description

ILC crashes when compiling the test project.

Reproduction Steps

dotnet publish -c Release -r win-x64 --self-contained

DelBench.zip

Expected behavior

File compiles

Actual behavior

EXEC : error An item with the same key has already been added. Key: __FrozenObj_DelBench_DelBench_DelFields9921

Regression?

Reproes on both main and preview4

Known Workarounds

No response

Configuration

Windows x64
Main/Preview 4

Other information

No response

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