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[DSE] Preserve basic block ordering using OrderedBasicBlock.

Authored by fhahn on Mar 25 2019, 11:19 AM.



By extending OrderedBB to allow removing and replacing cached
instructions, we can preserve OrderedBBs in DSE easily. This eliminates
one source of quadratic compile time in DSE.

Fixes PR38829.

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Event Timeline

fhahn created this revision.Mar 25 2019, 11:19 AM
Herald added a project: Restricted Project. · View Herald TranscriptMar 25 2019, 11:19 AM
efriedma added inline comments.Mar 25 2019, 12:55 PM
92 ↗(On Diff #192167)

Can you just set "LastInstFound = BB->end()", instead of actually numbering the new first instruction?

fhahn updated this revision to Diff 192207.Mar 25 2019, 2:26 PM

Thanks Eli. In the case LastInstFound == BB->begin(), we have to renumber all
instructions after removing LastInstFound, so there is no need to manually number
the next instruction with 0.

fhahn marked an inline comment as done.Mar 25 2019, 2:27 PM
This revision is now accepted and ready to land.Mar 25 2019, 2:48 PM
This revision was automatically updated to reflect the committed changes.