JIT: Avoid relying on bbNum to find lexical loop boundaries
#101714
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Switch `FlowGraphNaturalLoop::GetLexicallyTopMostBlock` and `FlowGraphNaturalLoop::GetLexicallyBottomMostBlock` to more robust implementations that scan the basic block list forwards (and backwards) to find the boundary blocks. Fix dotnet#101695
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch |
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cc @dotnet/jit-contrib PTAL @AndyAyersMS No diffs. Some minor TP regressions. |
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Can we port this to preview4 as well (assuming it's the fix for #101695)? dotnet/aspnetcore#55372 is still blocked on it |
Yes, we will port it. |
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Some timeouts, should we bypass build analysis here? |
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Yeah, I see similar timeouts in my other PR #100823 that started a run around the same time, so seems unlikely to be related to the change. |
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/ba-g Timeouts are also happening in other PRs and limited to linux-x64 |
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/backport to release/9.0-preview4 |
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Started backporting to release/9.0-preview4: https://github.com/dotnet/runtime/actions/runs/8898356760 |
…01714) Switch `FlowGraphNaturalLoop::GetLexicallyTopMostBlock` and `FlowGraphNaturalLoop::GetLexicallyBottomMostBlock` to more robust implementations that scan the basic block list forwards (and backwards) to find the boundary blocks. Fix dotnet#101695
…01714) Switch `FlowGraphNaturalLoop::GetLexicallyTopMostBlock` and `FlowGraphNaturalLoop::GetLexicallyBottomMostBlock` to more robust implementations that scan the basic block list forwards (and backwards) to find the boundary blocks. Fix dotnet#101695
The previous implementation is based on
bbNumand can subtly return the wrong results when the block list isn't sorted. This can happen in loop compaction (the bug existed since #96995 but seems to have been exposed by #99827).Switch
FlowGraphNaturalLoop::GetLexicallyTopMostBlockandFlowGraphNaturalLoop::GetLexicallyBottomMostBlockto more robust implementations that scan the basic block list forwards (and backwards) to find the boundary blocks.Fix #101695