diff options
Diffstat (limited to 'llvm/lib/CodeGen')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index d6defa5dc0b..7768d12c75c 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -6314,6 +6314,13 @@ SDValue DAGCombiner::visitRotate(SDNode *N) { if (isNullOrNullSplat(N1)) return N0; + // fold (rot x, c) -> x iff (c % BitSize) == 0 + if (isPowerOf2_32(Bitsize) && Bitsize > 1) { + APInt ModuloMask(N1.getScalarValueSizeInBits(), Bitsize - 1); + if (DAG.MaskedValueIsZero(N1, ModuloMask)) + return N0; + } + // fold (rot x, c) -> (rot x, c % BitSize) if (ConstantSDNode *Cst = isConstOrConstSplat(N1)) { if (Cst->getAPIntValue().uge(Bitsize)) { |
