Use hidden arguments for NativeAOT thunks

[jkotas]

Replace the TLS-based thunk context handoff with SecretStubArgument across supported architectures and remove the common-stub helpers.

RyuJIT must support the special hidden arguments for regular CoreCLR with JIT, so we can take advantage of it in NativeAOT to reduce amount of arch-specific asm code.

Depends on #132534

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[Copilot]

🟡 Changes recommended

The generated AMD64 and x86 thunk encodings use misaligned typed stores, introducing C++ undefined behavior.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Replaces NativeAOT’s TLS-based thunk context handoff with the hidden SecretStubArgument, building on #132534.

Changes:

• Adds hidden context parameters to delegate and interface thunks.
• Emits direct architecture-specific context loads and removes common-stub/TLS helpers.
• Preserves the x86 hidden argument across stack probing.

File summaries

File	Description
src/coreclr/tools/Common/TypeSystem/IL/Stubs/PInvokeILEmitter.cs	Passes hidden context to delegate helpers.
src/coreclr/tools/Common/TypeSystem/IL/Stubs/ILEmitter.cs	Adds a hidden-argument signature helper.
src/coreclr/tools/Common/TypeSystem/IL/Stubs/DelegateMarshallingMethodThunk.cs	Extends reverse delegate signatures.
src/coreclr/tools/aot/ILCompiler.Compiler/Compiler/CompilerTypeSystemContext.InterfaceThunks.cs	Uses hidden context for interface thunks.
src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/ThunkPool.cs	Removes common-stub configuration.
src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/RuntimeImports.cs	Removes obsolete runtime imports.
src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/InteropServices/PInvokeMarshal.cs	Accepts explicit thunk context.
src/coreclr/nativeaot/System.Private.CoreLib/src/System/Runtime/InteropServices/IDynamicInterfaceCastable.cs	Simplifies thunk-pool creation.
src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/CompilerHelpers/SharedCodeHelpers.cs	Removes TLS context retrieval.
src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/CompilerHelpers/InteropHelpers.cs	Forwards explicit context arguments.
src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Runtime/Augments/RuntimeAugments.cs	Simplifies thunk-heap API.
src/coreclr/nativeaot/Runtime/unix/unixasmmacrosarm64.inc	Removes obsolete TLS helper macro.
src/coreclr/nativeaot/Runtime/unix/PalUnix.cpp	Removes thunk TLS storage and exports.
src/coreclr/nativeaot/Runtime/ThunksMapping.cpp	Generates direct context/target thunk code.
src/coreclr/nativeaot/Runtime/riscv64/InteropThunksHelpers.S	Removes the RISC-V common stub.
src/coreclr/nativeaot/Runtime/portable.cpp	Removes obsolete portable stubs.
src/coreclr/nativeaot/Runtime/loongarch64/InteropThunksHelpers.S	Removes the LoongArch common stub.
src/coreclr/nativeaot/Runtime/i386/InteropThunksHelpers.asm	Removes the Windows x86 common stub.
src/coreclr/nativeaot/Runtime/CMakeLists.txt	Stops compiling common-stub assembly.
src/coreclr/nativeaot/Runtime/arm64/ThunkPoolThunks.S	Loads context directly on Unix ARM64.
src/coreclr/nativeaot/Runtime/arm64/ThunkPoolThunks.asm	Loads context directly on Windows ARM64.
src/coreclr/nativeaot/Runtime/arm64/InteropThunksHelpers.S	Removes the Unix ARM64 common stub.
src/coreclr/nativeaot/Runtime/arm64/InteropThunksHelpers.asm	Removes the Windows ARM64 common stub.
src/coreclr/nativeaot/Runtime/arm/InteropThunksHelpers.S	Removes the ARM common stub.
src/coreclr/nativeaot/Runtime/amd64/ThunkPoolThunks.S	Loads context directly on Unix AMD64.
src/coreclr/nativeaot/Runtime/amd64/ThunkPoolThunks.asm	Loads context directly on Windows AMD64.
src/coreclr/nativeaot/Runtime/amd64/InteropThunksHelpers.S	Removes the Unix AMD64 common stub.
src/coreclr/nativeaot/Runtime/amd64/InteropThunksHelpers.asm	Removes the Windows AMD64 common stub.
src/coreclr/jit/codegenxarch.cpp	Preserves the x86 hidden argument during stack probes.

Review details

Suppressed comments (1)

src/coreclr/nativeaot/Runtime/ThunksMapping.cpp:182

• This target-address field starts at byte offset 7, so writing through void** is an unaligned typed store and undefined behavior in C++. Use an unaligned-safe write for both absolute-address fields in this x86 thunk.

 *((void **)pCurrentThunkAddress) = pCurrentDataAddress + POINTER_SIZE;

• Files reviewed: 29/29 changed files
• Comments generated: 1
• Review effort level: Balanced