JIT: always home register params on wasm by AndyAyersMS · Pull Request #130446 · dotnet/runtime

AndyAyersMS · 2026-07-10T00:13:11Z

Always home the live params on Wasm (we do not produce or rely on the calleeRegArgMaskLiveIn). Initialize this anyways to avoid random behavior in case somebody does look at it.

Addresses the caller-side this-drop blocker in #129850.

SuperPMI (corelib crossgen2, browser): +28 bytes / 4 contexts / 0.00%.

Note

This change was authored with the assistance of GitHub Copilot.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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Pull request overview

This PR fixes a wasm-specific prolog correctness issue where register-parameter homing could be skipped due to calleeRegArgMaskLiveIn not being populated on wasm (since wasm uses WasmRegAlloc rather than LSRA). The change makes wasm always invoke genHomeRegisterParams during prolog generation and updates wasm’s homing filter to use ref-counts instead of entry liveness.

Changes:

In genFnProlog, always call genHomeRegisterParams under TARGET_WASM instead of gating on calleeRegArgMaskLiveIn.
In wasm genHomeRegisterParams, switch the “spill / don’t spill” decision from fgFirstBB->bbLiveIn to lvRefCnt().

Reviewed changes

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

File	Description
src/coreclr/jit/codegenwasm.cpp	Changes wasm parameter-homing eligibility check to use ref-counts rather than entry liveness.
src/coreclr/jit/codegencommon.cpp	Makes wasm prolog always home register params, bypassing the `calleeRegArgMaskLiveIn` gate used for LSRA-based targets.

…wasm Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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AndyAyersMS · 2026-07-10T00:50:16Z

@adamperlin PTAL
@dotnet/wasm-contrib FYI

This gets us bit farther through SPC bring up.

dotnet-policy-service · 2026-07-10T08:56:34Z

Tagging subscribers to 'arch-wasm': @lewing, @pavelsavara
See info in area-owners.md if you want to be subscribed.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

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Pull request overview

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

AndyAyersMS · 2026-07-10T22:46:08Z

Looks like we still have some older versions of node out there?

Console log: 'Directed_2' from job baee6d6c-7469-4026-9784-a026a91fe247 (azurelinux.3.amd64.open.rt) using docker image mcr.microsoft.com/dotnet-buildtools/prereqs:ubuntu-26.04-helix-webassembly-amd64@sha256:3ef1314b50ac039078f6406d649d5ac72715deccd07bcbfe3dd43fa438be3fbd on a00LCE7
...
Running: node --stack-size=8192 /root/helix/work/correlation/corerun.js -c /root/helix/work/correlation /root/helix/work/workitem/e/JIT/Directed/Directed_2/Directed_2.dll
failed to asynchronously prepare wasm: CompileError: WebAssembly.instantiate(): invalid value type 'exn', enable with --experimental-wasm-exnref @+58
warning: Loading from a file URI (file:///root/helix/work/correlation/corerun.wasm) is not supported in most browsers. See https://emscripten.org/docs/getting_started/FAQ.html#how-do-i-run-a-local-webserver-for-testing-why-does-my-program-stall-in-downloading-or-preparing
Aborted(CompileError: WebAssembly.instantiate(): invalid value type 'exn', enable with --experimental-wasm-exnref @+58)
file:///root/helix/work/correlation/corerun.js:461
  /** @suppress {checkTypes} */ var e = new WebAssembly.RuntimeError(what);
                                        ^

RuntimeError: Aborted(CompileError: WebAssembly.instantiate(): invalid value type 'exn', enable with --experimental-wasm-exnref @+58)
    at abort (file:///root/helix/work/correlation/corerun.js:461:41)
    at instantiateArrayBuffer (file:///root/helix/work/correlation/corerun.js:530:5)
    at async createWasm (file:///root/helix/work/correlation/corerun.js:608:16)
    at async createDotnetRuntime (file:///root/helix/work/correlation/corerun.js:7517:15)

Node.js v23.11.1

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pavelsavara · 2026-07-11T14:57:47Z

invalid value type 'exn', enable with --experimental-wasm-exnref @+58)
Node.js v23.11.1

Node version seems ok, we just need to pass --experimental-wasm-exnref in more scripts
#130550

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pavelsavara · 2026-07-11T19:11:08Z

Node version seems ok, we just need to pass --experimental-wasm-exnref in more scripts #130550

Fixed now @AndyAyersMS

Log

node version: v23.11.1
Timeout in ms: 900000
Running: node --experimental-wasm-exnref --stack-size=8192 /root/helix/work/correlation/corerun.js -c /root/helix/work/correlation /root/helix/work/workitem/e/JIT/Directed/Directed_2/Directed_2.dll
19:04:04.786 Running test: JIT/Directed/perffix/primitivevt/callconv3_d/callconv3_d.dll
PASSED

...

PASSED
19:04:05.416 Passed test: JIT/Directed/shift/uint16_ro/uint16_ro.dll
Kill watchdog with PID 46
Expected: 100
Actual: 100
END EXECUTION - PASSED

…d on entry liveness) Squashed net diff of dotnet#130446 onto the R2R prototype branch to fix the release-only wasm param-homing miscompile (this/args read from a frame home the prolog zeroed but never populated). Cherry-picking the 3 individual commits churns codegenwasm.cpp through an intermediate refcnt-based check; the net diff is the codegencommon.cpp calleeRegArgMaskLiveIn init + unconditional genHomeRegisterParams call, plus a comment in codegenwasm.cpp. Prototype-only; for the future WASI R2R PR, not for dotnet#130051. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Rebaselines the WASI R2R prototype onto current main (67 commits, now includes dotnet#130446 param-homing merged upstream 07-12). 4 trivial conflicts resolved in favor of origin/main (jiteeversionguid.h GUID token; wasi PAL stubs/file/map comment+null-check polish that landed via dotnet#130051 squash). dotnet#130446 de-duplicated cleanly (our cherry-pick == main's merged change). Prototype-only delta preserved: dotnet#130384 (inline pinvokes, still draft upstream), GAP1 (crossgen2 Program.cs +Wasi optimistic-ISA), static-compose corerun glue + JIT-EE WasmWellKnownGlobalSymbol additions. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

…arity Cherry-pick InitHelpers.cs from AndyAyersMS:next-blocker-spc — InitClass and InitInstantiatedClass return void* (null) instead of void, so the compiled wasm call_indirect signature matches the interp's value-returning P_ helper convention. Fixes the class-init helper arity mismatch (Console.cctor trap) that the rebaselined corelib-R2R composite hit at func 61854 after Gates 1+2 (dotnet#130384/dotnet#130446). Prototype-only; for the future WASI R2R PR. Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Always home the live params on Wasm (we do not produce or rely on the `calleeRegArgMaskLiveIn`). Initialize this anyways to avoid random behavior in case somebody does look at it. Addresses the caller-side `this`-drop blocker in #129850. SuperPMI (corelib crossgen2, browser): +28 bytes / 4 contexts / 0.00%. > [!NOTE] > This change was authored with the assistance of GitHub Copilot. --------- Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Co-authored-by: Pavel Savara <pavel.savara@gmail.com>

JIT: always home register params on wasm

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github-actions Bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Jul 10, 2026

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JIT: initialize calleeRegArgMaskLiveIn, match LSRA param liveness on …

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This was referenced Jul 10, 2026

The Operation will be canceled. The next steps may not contain expected logs. dotnet/dnceng#3008

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Flaky timeout in CreateFileChangeToken_RootDeletedAndRecreated_TokenFiresWhenFileCreated #129691

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pavelsavara added the arch-wasm WebAssembly architecture label Jul 10, 2026

JIT: sink calleeRegArgMaskLiveIn check into genHomeRegisterParams

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Running wasm with R2R'd System.Private.CoreLib #129850

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JIT: home wasm register params based on entry liveness

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Unable to pull image from mcr.microsoft.com #117164

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Merge branch 'main' into wasm-home-register-params

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Merge branch 'main' into wasm-home-register-params

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AndyAyersMS enabled auto-merge (squash) July 11, 2026 23:20

AndyAyersMS merged commit c9265d7 into dotnet:main Jul 12, 2026
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[main] Source code updates from dotnet/runtime dotnet/dotnet#7679

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AndyAyersMS commented Jul 10, 2026 •

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