Make it possible to order methods by specifying symbolic names

[MichalStrehovsky]

Text file with an ordered list of symbol names is much easier to emit based on sampling than MIBC (that requires methods in IL terms). Methods that are listed are generated in the specified order. Methods that are not listed are sorted by the compiler. Things that are listed but don't exist are silently skipped.

Cc @dotnet/ilc-contrib

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[Copilot]

Pull Request Overview

This PR introduces support for ordering emitted methods by providing a symbol list file, plus a corresponding smoke test and build integration.

• Adds a new --order option to ILCompiler and wires it through to the RyuJIT builder and file layout optimizer.
• Implements an explicit layout algorithm in FileLayoutOptimizer that reads symbol names from the specified order file.
• Updates the test suite with Ordering.cs, order.txt, and MSBuild targets to exercise and pass the order file to the native AOT compilation.

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/tests/nativeaot/SmokeTests/UnitTests/order.txt	New order file listing symbols for explicit layout
src/tests/nativeaot/SmokeTests/UnitTests/UnitTests.csproj	Added <IlcOrderFile> property and include Ordering.cs
src/tests/nativeaot/SmokeTests/UnitTests/Ordering.cs	Smoke test sorting method pointers by address
src/tests/nativeaot/SmokeTests/UnitTests/Main.cs	Added Ordering.Run to the test sequence
src/coreclr/tools/aot/ILCompiler/Program.cs	Integrated .UseSymbolOrder into the compilation builder
src/coreclr/tools/aot/ILCompiler/ILCompilerRootCommand.cs	Defined the --order CLI option
src/coreclr/tools/aot/ILCompiler.RyuJit/Compiler/RyuJitCompilationBuilder.cs	Added UseSymbolOrder and _orderFile field
src/coreclr/tools/aot/ILCompiler.RyuJit/Compiler/RyuJitCompilation.cs	Propagated orderFile to FileLayoutOptimizer
src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/FileLayoutOptimizer.cs	Implemented Explicit layout by reading the order file
src/coreclr/nativeaot/BuildIntegration/Microsoft.NETCore.Native.targets	Passed --order and --method-layout:explicit and included order file in inputs

Comments suppressed due to low confidence (2)

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/FileLayoutOptimizer.cs:208

• There are no existing tests validating that the Explicit layout algorithm actually applies the file's symbol order; consider adding unit or integration tests that inspect the generated layout to ensure the feature works as intended.

                case MethodLayoutAlgorithm.Explicit:

src/coreclr/tools/aot/ILCompiler.ReadyToRun/Compiler/FileLayoutOptimizer.cs:223

• [nitpick] Normalize or trim symbol names (e.g. strip leading underscores) when comparing against GetMangledName to ensure cross-platform consistency and avoid silent skips.

                            string symbolName = sr.ReadLine();

[MichalStrehovsky]

@dotnet/ilc-contrib could someone have a look at this? This is for a first party customer and I'd like this to make the next preview.

[agocke]

LGTM, a few questions about perf that aren't critical