[PATCH] D48223: DAG combine "and|or (select c, -1, 0), x" -> "select c, x, 0|-1"

[Stanislav Mekhanoshin via Phabricator via llvm-commits]

rampitec created this revision.
rampitec added reviewers: msearles, spatel.
Herald added subscribers: tpr, nhaehnle.

Normally this code with "and" opcode does not get to a DAG combiner
and simplified yet in the InstCombine. However AMDGPU produces it
during lowering and InstCombine has no chance to optimize it out.

In turn the same pattern with "or" opcode can reach DAG.

Since non-constant operand of and/or is now accepted both LHS and
RHS are now checked for select instruction.


https://reviews.llvm.org/D48223

Files:
  lib/CodeGen/SelectionDAG/DAGCombiner.cpp
  test/CodeGen/AMDGPU/dagcombine-select.ll
  test/CodeGen/AMDGPU/udivrem.ll

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