Changes in directory llvm/lib/CodeGen/SelectionDAG:
DAGCombiner.cpp updated: 1.216 -> 1.217 --- Log message: add a minor dag combine noticed when looking at PR945: http://llvm.org/PR945 --- Diffs of the changes: (+7 -0) DAGCombiner.cpp | 7 +++++++ 1 files changed, 7 insertions(+) Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp diff -u llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.216 llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.217 --- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.216 Thu Oct 12 10:22:24 2006 +++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Thu Oct 12 15:23:19 2006 @@ -1664,6 +1664,13 @@ return DAG.getNode(ISD::ANY_EXTEND, VT, SmallShift); } + // fold (srl (sra X, Y), 31) -> (srl X, 31). This srl only looks at the sign + // bit, which is unmodified by sra. + if (N1C && N1C->getValue()+1 == MVT::getSizeInBits(VT)) { + if (N0.getOpcode() == ISD::SRA) + return DAG.getNode(ISD::SRL, VT, N0.getOperand(0), N1); + } + // fold (srl (ctlz x), "5") -> x iff x has one bit set (the low bit). if (N1C && N0.getOpcode() == ISD::CTLZ && N1C->getValue() == Log2_32(MVT::getSizeInBits(VT))) { _______________________________________________ llvm-commits mailing list llvm-commits@cs.uiuc.edu http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
