Revert "Increase number of assertions (GlobalAP) + VN cache (#124132)" by AndyAyersMS · Pull Request #124928 · dotnet/runtime

AndyAyersMS · 2026-02-26T22:43:32Z

This reverts commit 92741be.

This was causing excessive memory allocation during jitting (see dotnet/dotnet#4933).

…24132)" This reverts commit 92741be.

AndyAyersMS · 2026-02-26T22:44:01Z

@EgorBo PTAL
FYI @dotnet/jit-contrib @janvorli

dotnet-policy-service · 2026-02-26T22:44:26Z

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

Copilot

Pull request overview

This PR reverts commit 92741be which introduced VN (Value Number) caching and a more sophisticated assertion count heuristic for the JIT's global assertion propagation optimization. The revert is necessary because the original changes caused excessive memory allocation during jitting.

Changes:

Restored the original simpler IL-size-based assertion count heuristic (using a lookup table based on IL code size)
Removed the VN-based caching mechanism (optAssertionVNsMap) and related helper method (optAssertionHasAssertionsForVN)
Reverted early-exit optimizations that relied on the VN cache

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/coreclr/jit/rangecheck.cpp	Reverted VN cache check back to simple `NoVN` check in `MergeEdgeAssertions`
src/coreclr/jit/compiler.h	Removed `optAssertionVNsMap` field and `optAssertionHasAssertionsForVN` method declaration
src/coreclr/jit/assertionprop.cpp	Restored original assertion count heuristic, removed VN caching logic in `optAddAssertion`, removed `optAssertionHasAssertionsForVN` implementation, and removed VN-based early-exit optimizations

adamperlin

I don't have the context to say what exactly is causing the issue here, but I'm signing off to unblock as this fix was confirmed to resolve the memory usage issue.

AndyAyersMS · 2026-02-27T02:02:31Z

/ba-g build analysis stuck

akoeplinger · 2026-02-27T08:39:34Z

do we need to revert #124306 as well? it was a follow-up to the PR reverted here

akoeplinger · 2026-02-27T10:33:56Z

/backport to release/11.0-preview2

github-actions · 2026-02-27T10:34:06Z

Started backporting to release/11.0-preview2 (link to workflow run)

AndyAyersMS · 2026-02-27T14:48:52Z

do we need to revert #124306 as well? it was a follow-up to the PR reverted here

I don't think we do? The VN cache was removed in the revert. cc @EgorBo

EgorBo · 2026-02-27T14:51:00Z

do we need to revert #124306 as well? it was a follow-up to the PR reverted here

I don't think we do? The VN cache was removed in the revert. cc @EgorBo

I suspect it should fail to compile without that PR, shouldn't be a correcntess issue

@akoeplinger

…AP) + VN cache (#124132)" (#124955) Backport of #124928 to release/11.0-preview2 /cc @akoeplinger @AndyAyersMS ## Customer Impact - [ ] Customer reported - [x] Found internally This was causing excessive memory allocation during jitting (see dotnet/dotnet#4933). ## Regression - [X] Yes - [ ] No Caused by: 92741be ## Testing Manual testing. ## Risk Low. Reverts an earlier change. [High/Medium/Low. Justify the indication by mentioning how risks were measured and addressed.] **IMPORTANT**: If this backport is for a servicing release, please verify that: - For .NET 8 and .NET 9: The PR target branch is `release/X.0-staging`, not `release/X.0`. - For .NET 10+: The PR target branch is `release/X.0` (no `-staging` suffix). ## Package authoring no longer needed in .NET 9 **IMPORTANT**: Starting with .NET 9, you no longer need to edit a NuGet package's csproj to enable building and bump the version. Keep in mind that we still need package authoring in .NET 8 and older versions. Co-authored-by: Andy Ayers <andya@microsoft.com>

…124132)'" Re-applies the changes from PR #124132 that were reverted in PR #124928 due to a bug causing excessive memory allocation during jitting. The bug has since been fixed. Changes: - Formula-based optMaxAssertionCount heuristic (basicBlocks + tracked locals) - VN cache (optAssertionHasAssertionsForVN) for fast O(1) lookup - optAssertionVNsMap field added to Compiler - optAddAssertion uses VN cache for duplicate detection/registration - Early return in optAssertionProp_LclVar when no assertions for VN - VN cache check in optAssertionVNIsNonNull - rangecheck.cpp uses optAssertionHasAssertionsForVN instead of NoVN check - Includes addOpVN pattern fix from PR #124306 Co-authored-by: EgorBo <523221+EgorBo@users.noreply.github.com>

…124132)'" (#125215) [Diffs](https://dev.azure.com/dnceng-public/public/_build/results?buildId=1321789&view=ms.vss-build-web.run-extensions-tab) Re-applies [#124132](#124132) which was reverted in [#124928](#124928) due to excessive JIT memory allocation. That root cause has since been fixed. ## Description **`assertionprop.cpp` / `compiler.h` — VN existence cache** - Adds `optAssertionVNsMap` (`VNSet*`): lazily-initialized map tracking which VNs have at least one assertion - Adds `optAssertionHasAssertionsForVN(vn, addIfNotFound)`: O(1) lookup; when `addIfNotFound=true` registers the VN on first insertion - `optAddAssertion`: uses the cache to gate the full O(n) table scan for duplicates; also registers `op2` bound VN and the `VN + const` operand VN (fix from [#124306](#124306)) so `MergeEdgeAssertions` can find them - `optAssertionProp_LclVar`: early-outs via cache before iterating assertions; pre-computes `treeVN` once instead of re-deriving it in the loop - `optAssertionVNIsNonNull`: skips iteration when cache says no assertions exist for the VN **`assertionprop.cpp` — `optMaxAssertionCount` heuristic** - Replaces the IL-code-size step-function table with the empirically-validated formula: ``` max(64, min(256, (lvaTrackedCount + 3 * fgBBcount + 48) >> 2)) ``` Validated across 1.1M compiled methods: 94.6% stay at the 64 floor, 0.4% hit the 256 cap, worst-case underprediction of 127 for 481 methods (0.043%). **`rangecheck.cpp`** - `MergeEdgeAssertions`: replaces `normalLclVN == NoVN` guard with `!optAssertionHasAssertionsForVN(normalLclVN)` — handles the `NoVN` case internally and also skips the loop when no relevant assertions were ever registered.  --- ✨ Let Copilot coding agent [set things up for you](https://github.com/dotnet/runtime/issues/new?title=✨+Set+up+Copilot+instructions&body=Configure%20instructions%20for%20this%20repository%20as%20documented%20in%20%5BBest%20practices%20for%20Copilot%20coding%20agent%20in%20your%20repository%5D%28https://gh.io/copilot-coding-agent-tips%29%2E%0A%0A%3COnboard%20this%20repo%3E&assignees=copilot) — coding agent works faster and does higher quality work when set up for your repo. --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: EgorBo <523221+EgorBo@users.noreply.github.com>

Revert "Increase number of assertions (GlobalAP) + VN cache (dotnet#1…

b63b9f4

…24132)" This reverts commit 92741be.

Copilot AI review requested due to automatic review settings February 26, 2026 22:43

github-actions bot added the area-CodeGen-coreclr CLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI label Feb 26, 2026

dotnet-policy-service bot assigned AndyAyersMS Feb 26, 2026

Copilot started reviewing on behalf of AndyAyersMS February 26, 2026 22:44 View session

Copilot AI reviewed Feb 26, 2026

View reviewed changes

AndyAyersMS requested a review from EgorBo February 26, 2026 23:03

adamperlin approved these changes Feb 27, 2026

View reviewed changes

AndyAyersMS merged commit 71ffd70 into dotnet:main Feb 27, 2026
132 of 134 checks passed

build-analysis bot mentioned this pull request Feb 27, 2026

[android][clr] No peer certificates when executing System.Net.Http.Functional.Tests on Android emulator #124526

Open

akoeplinger mentioned this pull request Feb 27, 2026

Memory blowing up during dotnet/dotnet repo build #124931

Closed

github-actions bot mentioned this pull request Feb 27, 2026

[release/11.0-preview2] Revert "Increase number of assertions (GlobalAP) + VN cache (#124132)" #124955

Merged

4 tasks

dotnet-maestro bot mentioned this pull request Feb 27, 2026

[main] Source code updates from dotnet/runtime dotnet/dotnet#5129

Merged

Copilot AI mentioned this pull request Mar 5, 2026

Revert "Revert 'Increase number of assertions (GlobalAP) + VN cache (#124132)'" #125215

Merged

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Revert "Increase number of assertions (GlobalAP) + VN cache (#124132)"#124928

Revert "Increase number of assertions (GlobalAP) + VN cache (#124132)"#124928
AndyAyersMS merged 1 commit intodotnet:mainfrom
AndyAyersMS:Revert124132

AndyAyersMS commented Feb 26, 2026

Uh oh!

AndyAyersMS commented Feb 26, 2026

Uh oh!

dotnet-policy-service bot commented Feb 26, 2026

Uh oh!

Copilot AI left a comment

Uh oh!

adamperlin left a comment

Uh oh!

AndyAyersMS commented Feb 27, 2026

Uh oh!

Uh oh!

akoeplinger commented Feb 27, 2026

Uh oh!

akoeplinger commented Feb 27, 2026

Uh oh!

github-actions bot commented Feb 27, 2026

Uh oh!

AndyAyersMS commented Feb 27, 2026

Uh oh!

EgorBo commented Feb 27, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

Conversation

AndyAyersMS commented Feb 26, 2026

Uh oh!

AndyAyersMS commented Feb 26, 2026

Uh oh!

dotnet-policy-service bot commented Feb 26, 2026

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

adamperlin left a comment

Choose a reason for hiding this comment

Uh oh!

AndyAyersMS commented Feb 27, 2026

Uh oh!

Uh oh!

akoeplinger commented Feb 27, 2026

Uh oh!

akoeplinger commented Feb 27, 2026

Uh oh!

github-actions bot commented Feb 27, 2026

Uh oh!

AndyAyersMS commented Feb 27, 2026

Uh oh!

EgorBo commented Feb 27, 2026

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants