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[Scalarizer] Treat values from unreachable blocks as undef
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Authored by uabelho on Nov 13 2019, 4:27 AM.

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Summary

When scalarizing PHI nodes we might try to examine/rewrite
InsertElement nodes in predecessors. If those predecessors
are unreachable from entry, then the IR in those blocks could
have unexpected properties resulting in infinite loops in
Scatterer::operator[].
By simply treating values originating from instructions in
unreachable blocks as undef we do not need to analyse them
further.

This fixes PR41723.

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Event Timeline

uabelho created this revision.Nov 13 2019, 4:27 AM
Herald added a project: Restricted Project. · View Herald TranscriptNov 13 2019, 4:27 AM
bjope added a subscriber: bjope.Nov 13 2019, 11:26 AM
bjope accepted this revision.Nov 14 2019, 10:46 PM

LGTM!

This revision is now accepted and ready to land.Nov 14 2019, 10:46 PM
This revision was automatically updated to reflect the committed changes.