JIT: Remove fallthrough constraint for BBJ_SWITCH -> BBJ_COND conversion
#105651
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Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch |
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cc @dotnet/jit-contrib, @AndyAyersMS PTAL. Small diffs. |
AndyAyersMS
approved these changes
Jul 30, 2024
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I noticed this unnecessary fallthrough check while exploring if we can avoid calling
fgUpdateFlowGraphagain after reordering blocks, as the new layout doesn't introduce any new blocks. Switch conversion shouldn't rely on what the current block layout happens to be when it's run; if we can do these transformations before running block layout, then removing the post-layoutfgUpdateFlowGraphcall should be a no-diff change.Local diffs are relatively small, though more
BBJ_SWITCH -> BBJ_CONDconversion tends to unlock other flow opts, like more block compaction (we currently skip compactingtargetintoblockiftargetis the successor a switch block, as we don't bother updating the switch block's successor table).