JIT: Tail-merge robust crossJumpVictim selection#129141
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* don't early out * make NoGcPoll preference explicit
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@AndyAyersMS PTAL. Makes the There are some few good diffs from avoiding splitting of from |
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Jun 25, 2026
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LGTM
@EgorBo can you also review
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| bool const isNoSplit = stmt == predBlock->firstStmt(); | ||
| bool const isFallThrough = (predBlock->KindIs(BBJ_ALWAYS) && predBlock->JumpsToNext()); | ||
| auto getRank = [=]() -> unsigned { |
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not sure I understand why you wrapped it to a single-use lambda, not a big fan of this approach.
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Previously,
crossJumpVictimselection logic was dependent on the order of candidates which can lead to random diffs.I removed the early out and added a tie-break which makes it order independent and sets the stage for a follow up zero-diff PR that processes all sets at once.
For the tie-break I used:
predBlock->bbNum < crossJumpVictim->bbNum. This actually has few good diffs because it preferences away fromBBF_NEEDS_GCPOLLblocks for some reason. I'd be nice to add that as a seperate heuristic instead of being implicitly encoded in the tie-break.