JIT: bail from optOptimizeBoolsCondBlock on GTF_UNSIGNED inputs#128928
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JIT: bail from optOptimizeBoolsCondBlock on GTF_UNSIGNED inputs#128928AndyAyersMS wants to merge 1 commit into
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optOptimizeBoolsCondBlock folds pairs of BBJ_COND blocks of the form "(x == 0) || (x relop 0)" into a single directional comparison. Mirror the existing check at the (LT,LT)/(LT,GE) folds and bail out if either input is unsigned. Possible a fix for dotnet#128895. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Pull request overview
This PR tightens OptBoolsDsc::optOptimizeBoolsCondBlock to avoid folding specific two-block boolean patterns into a signed directional compare when either original condition node is flagged GTF_UNSIGNED, preventing SetOper from accidentally making an originally-irrelevant unsigned flag become semantically meaningful after the fold.
Changes:
- Add early bail-outs in
optOptimizeBoolsCondBlockfor the “same local” fold cases when either input comparison node is marked unsigned. - Add a JitBlue regression test that enables Tiered Compilation + Tiered PGO and checks the runtime behavior of an OR-chain that previously could miscompile.
- Add a dedicated test
.csprojenabling process isolation and setting the requiredDOTNET_*environment variables for the repro scenario.
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
src/coreclr/jit/optimizebools.cpp |
Adds unsigned-flag bail-outs before performing signed directional folding that uses SetOper (which preserves flags). |
src/tests/JIT/Regression/JitBlue/Runtime_128895/Runtime_128895.cs |
New regression test that drives Tier0→Tier1+PGO and validates correct boolean results for the OR-chain scenario. |
src/tests/JIT/Regression/JitBlue/Runtime_128895/Runtime_128895.csproj |
Enables process isolation and sets DOTNET_TieredCompilation/DOTNET_TieredPGO to exercise the intended JIT pipeline in test runs. |
EgorBo
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Jun 3, 2026
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I feel like the entire function can be rewritten to be some sort of a table with rules like the one in RBO
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optOptimizeBoolsCondBlock folds pairs of BBJ_COND blocks of the form "(x == 0) || (x relop 0)" into a single directional comparison.
Mirror the existing check at the (LT,LT)/(LT,GE) folds and bail out if either input is unsigned.
Possible fix for #128895.