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ilspy-decompile

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Decompile .NET assemblies using ilspycmd CLI tool. Invoke when you need to inspect compiled DLLs, compare original vs patched assemblies, or examine compiler-generated types (closures, iterators, state machines).

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Source SKILL.md: https://github.com/Ourpalm/ILRuntime/blob/HEAD/.trae/skills/ilspy-decompile/SKILL.md

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ILSpy Command-Line Decompilation

Decompile .NET assemblies using ilspycmd to inspect compiled code structure, compare builds, and debug HybridPatch issues.

Prerequisites

ilspycmd is installed as a global .NET tool:

dotnet tool install --global ilspycmd

Common Commands

List all types in an assembly

ilspycmd -l MyLibrary.dll

Use this first to discover type names, especially compiler-generated ones.

Decompile a specific type

ilspycmd -t "Namespace.ClassName" MyLibrary.dll

For nested types, use / as separator: ilspycmd -t "Outer/Inner" MyLibrary.dll

Decompile entire assembly to stdout

ilspycmd MyLibrary.dll

Decompile to a project folder

ilspycmd MyLibrary.dll -p -o ./OutputDir

Decompile to a single file

ilspycmd MyLibrary.dll > Output.cs

Key Options

OptionDescription
-o, --output <dir>Set output directory or file path
-p, --projectExport as C# Visual Studio project
-t, --type <name>Decompile only the specified type
-lList types without full decompilation
--no-dead-codeRemove redundant compiler-generated blocks

Typical Workflow for HybridPatch Debugging

  1. List types in both original and patched DLLs to spot naming differences:

    ilspycmd -l HotfixAOT/bin/Release/net8.0/HotfixAOT.dll
ilspycmd -l HotfixAOT/bin/Release_Patched/net8.0/HotfixAOT.dll

  2. Compare compiler-generated types (closures <>c__DisplayClass*, state machines <Method>d__*):

    ilspycmd -t "HotfixAOT.SomeClass/<>c__DisplayClass0_0" original.dll
ilspycmd -t "HotfixAOT.SomeClass/<>c__DisplayClass0_0" patched.dll

  3. Inspect injected DLL to verify injection results:

    ilspycmd -t "HotfixAOT.SomeClass" HotfixAOT/Patched/HotfixAOT.dll

  4. Check hash file for type name mappings after FixClosureNameConsistency:

    • The .hash file records type hashes used for closure renaming
    • Compare type names in hash vs actual DLL to find mismatches

Key Paths in This Project

  • Original (Release) DLL: HotfixAOT/bin/Release/net8.0/HotfixAOT.dll
  • Patched (Release_Patched) DLL: HotfixAOT/bin/Release_Patched/net8.0/HotfixAOT.dll
  • Injected + Patched DLL: HotfixAOT/Patched/HotfixAOT.dll
  • Hash file: HotfixAOT/Patched/HotfixAOT.hash
  • Patch file: HotfixAOT/Patched/HotfixAOT.patch