Use explicit secret arguments in IL stubs

[jkoritzinsky]

Summary

• represent IL stub secret context as an explicit native int modreq(SecretStubArgument) parameter
• remove StubHelpers.GetStubContext() and the obsolete publish-secret-parameter consumption paths
• update JIT, interpreter, VM, and ABI documentation to use the explicit argument

Validation

• checked CoreCLR build
• reverse P/Invoke struct marshalling test
• COM extension points test
• calling-convention tests under JIT and interpreter mode
• JIT formatting

Note

This pull request description was generated by GitHub Copilot.

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[Copilot]

Pull request overview

Updates CoreCLR IL stub plumbing so the “secret” stub context is represented and consumed via an explicit native int parameter annotated with the SecretStubArgument required modifier, removing the older StubHelpers.GetStubContext() / publish-secret-parameter paths. This aligns the VM, JIT, interpreter, SuperPMI tooling, and ABI docs around a single mechanism for identifying and binding the secret stub argument register.

Changes:

• Adds explicit SecretStubArgument handling in stub generation and IL emission, and removes the StubHelpers.GetStubContext() intrinsic path.
• Removes CORJIT_FLAG_PUBLISH_SECRET_PARAM, replaces it with a new method attribute flag (CORINFO_FLG_HAS_MD_CONTEXT_ARG) and updates JIT/interpreter consumption accordingly.
• Updates SuperPMI dumps, JIT interface type definitions, and ABI documentation to reflect the new model.

Reviewed changes

Copilot reviewed 39 out of 39 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/coreclr/vm/stubgen.h	Adds secret-arg placeholder constant, tracking index, and IL emission helper.
src/coreclr/vm/stubgen.cpp	Patches placeholder LDARG to the real index during linking; tracks secret-arg index.
src/coreclr/vm/jitinterface.cpp	Exposes new method flag for stubs with an MD context argument; recognizes SecretStubArgument modreq.
src/coreclr/vm/dllimport.h	Replaces stub-context load helper with signature augmentation helper for secret argument.
src/coreclr/vm/dllimport.cpp	Appends SecretStubArgument to signatures where needed and updates stub IL to load it via LDARG.
src/coreclr/vm/corelib.h	Removes binding for StubHelpers.GetStubContext.
src/coreclr/tools/superpmi/superpmi-shared/spmidumphelper.cpp	Adds dump support for CORINFO_FLG_HAS_MD_CONTEXT_ARG; removes dump of publish-secret JIT flag.
src/coreclr/tools/superpmi/superpmi-shared/methodcontext.cpp	Removes CORJIT_FLAG_PUBLISH_SECRET_PARAM stringification.
src/coreclr/tools/Common/JitInterface/CorInfoTypes.cs	Adds CORINFO_FLG_HAS_MD_CONTEXT_ARG; removes CORJIT_FLAG_PUBLISH_SECRET_PARAM.
src/coreclr/System.Private.CoreLib/src/System/StubHelpers.cs	Removes the GetStubContext intrinsic stub.
src/coreclr/jit/targetx86.h	Updates comment for REG_SECRET_STUB_PARAM to match explicit SecretStubArgument usage.
src/coreclr/jit/targetwasm.h	Same comment update for wasm target.
src/coreclr/jit/targetriscv64.h	Same comment update for riscv64 target.
src/coreclr/jit/targetloongarch64.h	Same comment update for loongarch64 target.
src/coreclr/jit/targetarm64.h	Same comment update for arm64 target.
src/coreclr/jit/targetarm.h	Same comment update for arm target.
src/coreclr/jit/targetamd64.h	Same comment update for amd64 target.
src/coreclr/jit/namedintrinsiclist.h	Removes named intrinsic entry for StubHelpers.GetStubContext.
src/coreclr/jit/morph.cpp	Switches frame-pointer GC-info requirement to new “has MD context arg” signal.
src/coreclr/jit/lsrabuild.cpp	Removes publish-secret-param live-in handling (now modeled via explicit parameter).
src/coreclr/jit/lower.cpp	Uses MD-context-arg + explicit secret arg local to populate InlinedCallFrame secret field.
src/coreclr/jit/lclvars.cpp	Tracks SecretStubArgument parameter as a well-known arg and adjusts stack-space logic.
src/coreclr/jit/jitee.h	Removes JIT_FLAG_PUBLISH_SECRET_PARAM mapping.
src/coreclr/jit/importercalls.cpp	Removes import-time intrinsic expansion for GetStubContext; handles SecretStubArgument modifier on call args.
src/coreclr/jit/flowgraph.cpp	Uses presence of explicit secret stub arg for reverse pinvoke tracking and uses MD-context-arg for frame sizing.
src/coreclr/jit/compiler.hpp	Stops treating the old stub-arg temp as a special “never zero-init” var.
src/coreclr/jit/compiler.h	Adds helpers to query presence of explicit secret stub arg and MD-context-arg flag; removes compPublishStubParam.
src/coreclr/jit/compiler.cpp	Removes allocation/initialization of the old “published stub argument” temp.
src/coreclr/jit/codegenxarch.cpp	Updates stack-probing path to preserve secret stub register based on explicit-secret-arg presence.
src/coreclr/jit/codegenloongarch64.cpp	Updates assertions to key off explicit-secret-arg presence.
src/coreclr/jit/codegencommon.cpp	Removes homing/spilling logic tied to the old publish-secret-param mechanism.
src/coreclr/jit/codegenarm64.cpp	Updates assertions to key off explicit-secret-arg presence.
src/coreclr/jit/codegenarm.cpp	Updates assertions to key off explicit-secret-arg presence.
src/coreclr/interpreter/intrinsics.cpp	Removes interpreter named intrinsic lookup for GetStubContext.
src/coreclr/interpreter/compiler.cpp	Detects SecretStubArgument modifier on parameters and removes intrinsic-based expansion path.
src/coreclr/inc/jiteeversionguid.h	Bumps JIT/EE interface GUID for flag/contract changes.
src/coreclr/inc/corjitflags.h	Removes CORJIT_FLAG_PUBLISH_SECRET_PARAM.
src/coreclr/inc/corinfo.h	Adds CORINFO_FLG_HAS_MD_CONTEXT_ARG and keeps SecretStubArgument modifier flag.
docs/design/coreclr/botr/clr-abi.md	Updates ABI documentation to describe SecretStubArgument as an explicit parameter.

[jkotas]

Can we make the logic positive and check for stubs that do need the hidden arg - it will make it easier to match the conditions with the emitter. I think it should be just:

if (SF_IsForwardStub(dwStubFlags))
{
if (SF_IsVarArgStub(dwStubFlags))
return true;
}
else
{
// All native-managed stub need the hidden arg currently
return true;
}

[jakobbotsch]

You can delete genSpillOrAddNonStandardRegisterParam.

[Copilot]

Pull request overview

Copilot reviewed 39 out of 39 changed files in this pull request and generated no new comments.

Suppressed comments (1)

src/coreclr/jit/flowgraph.cpp:1862

• The comment describing the Reverse P/Invoke helper’s third argument is misleading: the secret stub argument passed here is thunk data (e.g., UMEntryThunkData*) that the helper uses to recover the target MethodDesc, not the MethodDesc itself. Updating the comment would avoid future confusion while working on this code path.

 // If we have a secret param for a Reverse P/Invoke, that means that we are in an IL stub.
// In this case, the method handle we pass down to the Reverse P/Invoke helper should be
// the target method, which is passed in the secret parameter.

[jakobbotsch]

Can you instead switch the Windows ABI case to base the result on lvaGetRelativeOffsetToCallerAllocatedSpaceForParameter?