[SelectionDAG] Provide default expansion for rotates

Implement default legalization of rotates: either in terms of the rotation
in the opposite direction (if legal), or in terms of shifts and ors.

Implement generating of rotate instructions for Hexagon. Hexagon only
supports rotates by an immediate value, so implement custom lowering of
ROTL/ROTR on Hexagon. If a rotate is not legal, use the default expansion.

Differential Revision: https://reviews.llvm.org/D47725

llvm-svn: 334497

1 files changed, 12 insertions, 0 deletions

diff --git a/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp b/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
index 9f75fddc316..4fe6e3a9621 100644
--- a/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonISelLowering.cpp
@@ -1507,6 +1507,10 @@ HexagonTargetLowering::HexagonTargetLowering(const TargetMachine &TM,
 
   // Subtarget-specific operation actions.
   //
+  if (Subtarget.hasV60TOps()) {
+    setOperationAction(ISD::ROTL, MVT::i32, Custom);
+    setOperationAction(ISD::ROTL, MVT::i64, Custom);
+  }
   if (Subtarget.hasV5TOps()) {
     setOperationAction(ISD::FMA,  MVT::f64, Expand);
     setOperationAction(ISD::FADD, MVT::f64, Expand);
@@ -2092,6 +2096,13 @@ HexagonTargetLowering::LowerVECTOR_SHIFT(SDValue Op, SelectionDAG &DAG) const {
 }
 
 SDValue
+HexagonTargetLowering::LowerROTL(SDValue Op, SelectionDAG &DAG) const {
+  if (isa<ConstantSDNode>(Op.getOperand(1).getNode()))
+    return Op;
+  return SDValue();
+}
+
+SDValue
 HexagonTargetLowering::LowerBITCAST(SDValue Op, SelectionDAG &DAG) const {
   MVT ResTy = ty(Op);
   SDValue InpV = Op.getOperand(0);
@@ -2792,6 +2803,7 @@ HexagonTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
     case ISD::SRA:
     case ISD::SHL:
     case ISD::SRL:                  return LowerVECTOR_SHIFT(Op, DAG);
+    case ISD::ROTL:                 return LowerROTL(Op, DAG);
     case ISD::ConstantPool:         return LowerConstantPool(Op, DAG);
     case ISD::JumpTable:            return LowerJumpTable(Op, DAG);
     case ISD::EH_RETURN:            return LowerEH_RETURN(Op, DAG);