JIT: Centralize WellKnownArg definitions

[jakobbotsch]

Use a single wellknownargs.h that is included multiple times to build various pieces of information we query about arguments. Rewrite users in terms of columns defined in that file.

Fix#130227

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[Copilot]

Pull request overview

This PR centralizes WellKnownArg metadata into a single wellknownargs.h “X-macro” list that is included multiple times to generate the enum and related query helpers, and it adjusts GDV candidate argument handling to avoid asserting on unexpected well-known args.

Changes:

• Introduces src/coreclr/jit/wellknownargs.h as the single source of truth for WellKnownArg entries and their metadata.
• Rewrites WellKnownArg-related helpers (getWellKnownArgName, CallArg::IsUserArg, CallArg::IsArgAddedLate, arg dump short names) to be table-driven from wellknownargs.h.
• Updates GDV compatibility checking to skip non-signature arguments via CallArg::IsUserArg() instead of asserting on “unexpected” well-known args.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/coreclr/jit/wellknownargs.h	New centralized table defining well-known args and their metadata.
src/coreclr/jit/morph.cpp	Converts getWellKnownArgName to use the centralized table.
src/coreclr/jit/importercalls.cpp	Updates GDV arg filtering logic; also includes a small indentation-only change.
src/coreclr/jit/importer.cpp	Refactors inline arg init to use IsUserArg/InstParam instead of a well-known switch.
src/coreclr/jit/gentree.h	Generates WellKnownArg enum members from the centralized table.
src/coreclr/jit/gentree.cpp	Table-driven IsArgAddedLate, IsUserArg, and short-name lookup for arg messages.
src/coreclr/jit/fginline.cpp	Refactors inline argument setup logic to use IsUserArg/InstParam.
src/coreclr/jit/compiler.hpp	Stops tagging the helper “method handle” arg as a well-known arg.
src/coreclr/jit/CMakeLists.txt	Adds wellknownargs.h to the JIT header list.

Comments suppressed due to low confidence (1)

src/coreclr/jit/importercalls.cpp:7648

• Extra leading spaces were introduced on this loop and its body, making indentation inconsistent with the surrounding block and adding whitespace-only noise.

 for (UINT32 i = 0; i < numberOfMethods; i++)
{
CORINFO_CONST_LOOKUP lookup = {};
info.compCompHnd->getFunctionFixedEntryPoint((CORINFO_METHOD_HANDLE)likelyMethods[i].handle, false,
&lookup);

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated no new comments.

[jakobbotsch]

cc @dotnet/jit-contrib PTAL @AndyAyersMS

Think this was exposed by recent devirtualization work, we started seeing calls with async context arguments for method-based GDVs and it did not expect to see those arguments.