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[PatternMatch] Make m_c_ICmp swap the predicate (PR42801)
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Authored by nikic on Jan 18 2020, 4:13 AM.

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Summary

This addresses https://bugs.llvm.org/show_bug.cgi?id=42801. The m_c_ICmp() matcher is changed to provide the swapped predicate it the operands are swapped.

Existing uses of m_c_ICmp() fall in one of two categories: Working on equality predicates only, where swapping is irrelevant. Or performing a manual swap, in which case this patch removes it.

The only exception is the foldICmpWithLowBitMaskedVal() fold, which does not swap the predicate, and instead reasons about whether a swap occurred or not for each predicate. Getting the swapped predicate allows us to merge the logic for pairs of predicates, instead of duplicating it.

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Event Timeline

nikic created this revision.Jan 18 2020, 4:13 AM
Herald added a project: Restricted Project. · View Herald TranscriptJan 18 2020, 4:13 AM
spatel accepted this revision.Jan 20 2020, 6:12 AM

LGTM

llvm/include/llvm/IR/PatternMatch.h
1887

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This revision is now accepted and ready to land.Jan 20 2020, 6:12 AM
This revision was automatically updated to reflect the committed changes.