JIT: don't merge assertions from orphaned pred blocks - #131471
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JIT: don't merge assertions from orphaned pred blocks#131471AndyAyersMS wants to merge 1 commit into
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RBO's jump threading can leave a block with bbPreds == nullptr without deleting it, and phi-arg gtPredBB references to that block are never rewritten. RangeCheck::MergeAssertion read those edge assertions unconditionally, producing wrong-code when the stale edge's outgoing assertions don't hold on any live path into the phi's block. Guard the phi-arg case with the same isUnreachableBlock check that optVisitReachingAssertions uses. Fixes dotnet#131404, dotnet#131436. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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@EgorBo PTAL A couple of SPMI diffs More notes here: #131436 (comment) |
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Pull request overview
This PR hardens JIT range analysis against unreachable/orphaned predecessor blocks by skipping edge-assertion merges for GT_PHI_ARG inputs when the phi’s recorded predecessor block is effectively unreachable (no normal predecessors, not the entry block, and not a handler-begin).
Changes:
- Add an unreachable/orphaned predecessor guard in
RangeCheck::MergeAssertionfor theGT_PHI_ARGpath. - Avoid merging edge assertions from such unreachable predecessor blocks, aligning behavior with the existing guard in
Compiler::optVisitReachingAssertions.
EgorBo
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Jul 28, 2026
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RBO's jump threading can leave a block with bbPreds == nullptr without deleting it, and phi-arg gtPredBB references to that block are never rewritten. RangeCheck::MergeAssertion read those edge assertions unconditionally, producing wrong-code when the stale edge's outgoing assertions don't hold on any live path into the phi's block.
Guard the phi-arg case with the same isUnreachableBlock check that optVisitReachingAssertions uses.
Fixes #131404, #131436.