[Wasm RyuJIT] Add Instruction Encoding for Local Var Declarations and Emit Local Declarations

[adamperlin]

This PR adds a new instrDesc subtype for encoding Wasm local declarations, which have the form count: u32 type:valtype, where valtype can be encoded as a single byte for number and vector types.

The PR also adds code to emit local count and local declarations as part of the prolog for a function. Some of this may need to change based on what we decide around calling convention and register (locals) allocation.

[Copilot]

Pull request overview

This PR introduces support for WebAssembly local variable declarations in the JIT compiler by adding a new instruction descriptor subtype and emission logic for encoding local declarations in the function prolog.

Key Changes

• Adds instWasmValueType enum and mapping functions to convert between JIT types and WASM types
• Introduces instrDescLclVarDecl instruction descriptor for encoding local declarations with count and type
• Implements local declaration emission in the function prolog via genWasmLocals()

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 12 comments.

Show a summary per file

File	Description
src/coreclr/jit/wasmtypesdef.h	New header defining WASM value types and type conversion functions
src/coreclr/jit/registeropswasm.h	Removes trailing blank line
src/coreclr/jit/instrswasm.h	Adds local_cnt and local_decl instructions
src/coreclr/jit/emitwasm.h	Declares new emission methods for local declarations
src/coreclr/jit/emitwasm.cpp	Implements local declaration emission and descriptor handling
src/coreclr/jit/emitfmtswasm.h	Adds IF_LOCAL_CNT and IF_LOCAL_DECL instruction formats
src/coreclr/jit/emit.h	Adds instrDescLclVarDecl structure and bitfield flag
src/coreclr/jit/codegenwasm.cpp	Adds INS_end instruction to epilog
src/coreclr/jit/codegencommon.cpp	Implements prolog local count and declaration emission
src/coreclr/jit/codegen.h	Declares genWasmLocals() method

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[AndyAyersMS]

Mostly looks good, just one issue with the epilog.

[SingleAccretion]

Looking pretty good! Just a few comments.

[adamperlin]

Mostly looks good, just one issue with the epilog.

@AndyAyersMS thanks for catching that. This should be fixed now if you'd like to take another look!

[AndyAyersMS]

Looks good!

[AndyAyersMS]

Looks like superpmi diffs is just generally broken in CI (nothing to do with this PR). Let me see if I can figure out why.

Failing log entry

[13:50:40] Using JIT/EE Version from mcs: d1188f9b-d81e-487a-b525-cedb10d15c8e
Error: JIT not found at diff_jit_path /tmp/helix/working/B83F0A11/p/diff/checked/libclrjit_unix_arm64_arm64.dylib

It should be looking for libclrjit_universal_arm64_arm64.dylib... wonder if I broke this with my SPMI script changes for wasm.

[AndyAyersMS]

I am going to cherry-pick my script fix into your PR if that's ok.

[adamperlin]

I am going to cherry-pick my script fix into your PR if that's ok.

Yes that is fine! Thanks for investigating that failure!