JIT: propagate vector constants through assertion prop by EgorBo · Pull Request #127124 · dotnet/runtime

EgorBo · 2026-04-19T23:14:39Z

Add a new kind of an assertion - O2K_CONST_VEC.

if (vec == Vector128<int>.Zero)
{
    // jit now constant propagates all `vec` uses with Vector128<int>.Zero here
}

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Copilot

Pull request overview

This PR extends CoreCLR JIT assertion propagation to recognize and propagate SIMD (vector) constants across equality/inequality guards, enabling more constant folding in common “guard then use” patterns for Vector64/128/256/512 integral vectors.

Changes:

Added a new assertion operand kind O2K_CONST_VEC backed by an arena-allocated simd_t, including equality/printing/factory support.
Taught optAssertionGenJtrue / assertion creation to recognize Vector*_op_Equality/op_Inequality patterns against GT_CNS_VEC and produce usable assertions (excluding FP base types).
Implemented SIMD constant materialization during propagation (including VN-based propagation into SIMD-typed loads such as byref ABI patterns).

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Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/coreclr/jit/compiler.h	Adds `O2K_CONST_VEC` plumbing to assertion descriptors, including storage, equality, and factory helpers; extends propagation eligibility for VN-based SIMD constants.
src/coreclr/jit/assertionprop.cpp	Recognizes SIMD compare patterns when generating assertions and propagates vector constants (including VN-based propagation for SIMD loads).

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

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Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/e8f6f2ee-359c-4b32-b822-877ec029ddc6 Co-authored-by: EgorBo <523221+EgorBo@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

EgorBo · 2026-04-24T10:18:24Z

/ba-g timeouts

…tNode When `op1` is not invariant or a local, `fgMakeMultiUse(&op1)` rewrites `op1` into `COMMA(STORE temp, LCL_VAR temp)` and returns a fresh load of `temp`. The STORE is the only place `temp` is written, so it must evaluate before any later read of `temp`. The non-AVX-512 branch passed the clean clone as the first argument of `AND_NOT` and the COMMA-wrapped tree as the second. `AND_NOT(a, b)` decomposes into `AND(a, NOT(b))`, so `a` evaluates first - meaning the `LCL_VAR temp` read happened before the STORE inside `b`, producing garbage for the non-NaN'd input. The bug was latent: prior to dotnet#127124 / dotnet#127402 the inner `IsNaN(op1)` expanded into real per-element compares that kept enough materialization around to mask the bad ordering. With SIMD32/64 constant propagation, `CompareNotEqual(temp, temp)` value-numbers as AllBitsSet and the entire right subtree collapses to constants, leaving only the broken left-side read - which is what the `Vector512Tests.ConvertToInt32Test` failure on non-AVX-512 hosts (libraries-jitstress-random, nativeaot-outerloop, iossimulator) was actually exercising. Fix: pass `op1` (the COMMA, evaluated first) as `AND_NOT`'s first argument and use the side-effect-free `op1Clone1` for the IsNaN check. Verified by repro on a non-AVX-512 host (DOTNET_EnableAVX512=0): Vector512.ConvertToInt32(Vector512.Create(float.MinValue)) now returns Vector512<int>.Create(int.MinValue) as expected. SPMI benchmarks.run replay clean. Fixes dotnet#127440. Supersedes dotnet#127499 (which gated unreachable code in `impSpecialIntrinsic` - `NI_Vector512_ConvertToInt32` is already filtered upstream by `lookupId` on non-AVX-512 hosts, so that gate did not actually fix the failure). Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot AI review requested due to automatic review settings April 19, 2026 23:14

github-actions Bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Apr 19, 2026

Copilot started reviewing on behalf of EgorBo April 19, 2026 23:15 View session

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EgorBo marked this pull request as draft April 19, 2026 23:17

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EgorBo added 2 commits April 20, 2026 02:14

Add assertions for simd

d27ab37

Add assertions for simd

284554b

EgorBo force-pushed the vec-aprop-const branch from a80041e to 284554b Compare April 20, 2026 02:38

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This was referenced Apr 20, 2026

[wasm] WBT SatelliteAssembliesTests.CheckThatSatelliteAssembliesAreNotAOTed failing #90458

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System.Net.NameResolution.Tests DNS failures: Name or service not known #126641

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EgorBo commented Apr 20, 2026

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Copilot started work on behalf of EgorBo April 20, 2026 14:20 View session

Limit SIMD assertion payload to simd16_t for const vec assertions

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Agent-Logs-Url: https://github.com/dotnet/runtime/sessions/e8f6f2ee-359c-4b32-b822-877ec029ddc6 Co-authored-by: EgorBo <523221+EgorBo@users.noreply.github.com>

Copilot finished work on behalf of EgorBo April 20, 2026 15:15

EgorBo marked this pull request as ready for review April 20, 2026 18:12

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build-analysis Bot mentioned this pull request Apr 20, 2026

Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. dotnet/dnceng#5922

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tannergooding reviewed Apr 21, 2026

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tannergooding approved these changes Apr 23, 2026

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EgorBo enabled auto-merge (squash) April 23, 2026 02:38

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browser-wasm linux Release LibraryTests queues timing out #117974

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ProcessSafeHandle_WaitForExitOrKillOnCancellationAsync_KillsOnCancellation failuring in CI #127287

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Copilot AI mentioned this pull request Apr 23, 2026

Fix race condition: set _canceled before SignalCore in ProcessWaitState #127312

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EgorBo merged commit 812f3a1 into main Apr 24, 2026
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EgorBo deleted the vec-aprop-const branch April 24, 2026 10:18

tannergooding mentioned this pull request Apr 24, 2026

Allow O2K_CONST_VEC to handle some TYP_SIMD32/64 #127390

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dotnet-maestro Bot mentioned this pull request Apr 25, 2026

[main] Source code updates from dotnet/runtime dotnet/dotnet#6272

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mangod9 mentioned this pull request Apr 28, 2026

Test failure: System.Runtime.Intrinsics.Tests.Vectors.Vector512Tests.ConvertToInt32Test #127440

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MichalStrehovsky mentioned this pull request Apr 28, 2026

Vectors tests fail on native AOT #127494

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Copilot AI mentioned this pull request Apr 28, 2026

JIT: gate Vector512.ConvertToInt32(Native) on AVX-512 #127499

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EgorBo mentioned this pull request Apr 28, 2026

JIT: fix Vector{128,256}.ConvertToInt32 use-before-def in gtNewSimdCvtNode #127524

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EgorBo commented Apr 24, 2026

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EgorBo commented Apr 19, 2026 •

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