JIT: don't let tail-merge try and remove the OSR-protected entry block#131164
JIT: don't let tail-merge try and remove the OSR-protected entry block#131164AndyAyersMS wants to merge 1 commit into
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Fixes dotnet#131056 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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@jakobbotsch PTAL |
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Pull request overview
This PR prevents fgHeadTailMerge from removing the OSR-protected original entry block (fgEntryBB) while it still has an artificial bbRefs increment applied during import. This avoids hitting fgRemoveBlock assertions that require removed blocks to have bbRefs == 0 and bbPreds == nullptr.
Changes:
- Add an OSR-specific guard in tail-merge block removal to skip removing
fgEntryBBwhile it is still tracked as the “original method entry”. - Add an explanatory comment documenting the OSR artificial
bbRefsbump / unprotect sequence.
AndyAyersMS
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Thank you for the fix. |
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Rerunning failed build. |
| // Try to remove emptyBlock and make its preds jump directly to newTarget. | ||
| // Under OSR, the original method entry (fgEntryBB) has an artificial bbRefs | ||
| // bump to keep it live until morph un-protects it; removing it here would | ||
| // leave that ref dangling and trip asserts in fgRemoveBlock. | ||
| // | ||
| bool canRemove = | ||
| !emptyBlock->HasFlag(BBF_DONT_REMOVE) && (emptyBlock != fgFirstBB) && (emptyBlock != fgOSREntryBB); | ||
| bool canRemove = !emptyBlock->HasFlag(BBF_DONT_REMOVE) && (emptyBlock != fgFirstBB) && | ||
| (emptyBlock != fgOSREntryBB) && (!opts.IsOSR() || (emptyBlock != fgEntryBB)); |
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It's a nit, but I assume this could just be emptyBlock != fgEntryBB, isn't fgEntryBB always null outside OSR?
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LGTM, feel free to ignore
Fixes #131056