[PATCH] D47735: [SelectionDAG] Create rotates more aggressively

Krzysztof Parzyszek via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Mon Jun 4 12:04:26 PDT 2018


kparzysz created this revision.
kparzysz added reviewers: spatel, eli.friedman.

The DAG combiner can recognize a pattern of ORed shifts that evaluate to a bit rotation. When the rotation is ORed with another value, the OR operations can get reassociated in such a way that the rotation will no longer be identified. This patch implements a more aggressive analysis of OR operations to detect rotation patterns.


Repository:
  rL LLVM

https://reviews.llvm.org/D47735

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  test/CodeGen/Hexagon/rotate.ll

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