1 files changed, 32 insertions, 5 deletions
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index c78d3fa45c5..8880e9d88fb 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -204,11 +204,23 @@ PPCTargetLowering::PPCTargetLowering(const PPCTargetMachine &TM,
   setOperationAction(ISD::FNEARBYINT, MVT::ppcf128, Expand);
   setOperationAction(ISD::FREM, MVT::ppcf128, Expand);
 
-  // PowerPC has no SREM/UREM instructions
-  setOperationAction(ISD::SREM, MVT::i32, Expand);
-  setOperationAction(ISD::UREM, MVT::i32, Expand);
-  setOperationAction(ISD::SREM, MVT::i64, Expand);
-  setOperationAction(ISD::UREM, MVT::i64, Expand);
+  // PowerPC has no SREM/UREM instructions unless we are on P9
+  // On P9 we may use a hardware instruction to compute the remainder.
+  // The instructions are not legalized directly because in the cases where the
+  // result of both the remainder and the division is required it is more
+  // efficient to compute the remainder from the result of the division rather
+  // than use the remainder instruction.
+  if (Subtarget.isISA3_0()) {
+    setOperationAction(ISD::SREM, MVT::i32, Custom);
+    setOperationAction(ISD::UREM, MVT::i32, Custom);
+    setOperationAction(ISD::SREM, MVT::i64, Custom);
+    setOperationAction(ISD::UREM, MVT::i64, Custom);
+  } else {
+    setOperationAction(ISD::SREM, MVT::i32, Expand);
+    setOperationAction(ISD::UREM, MVT::i32, Expand);
+    setOperationAction(ISD::SREM, MVT::i64, Expand);
+    setOperationAction(ISD::UREM, MVT::i64, Expand);
+  }
 
   // Don't use SMUL_LOHI/UMUL_LOHI or SDIVREM/UDIVREM to lower SREM/UREM.
   setOperationAction(ISD::UMUL_LOHI, MVT::i32, Expand);
@@ -8394,6 +8406,18 @@ SDValue PPCTargetLowering::LowerINTRINSIC_VOID(SDValue Op,
   return SDValue();
 }
 
+SDValue PPCTargetLowering::LowerREM(SDValue Op, SelectionDAG &DAG) const {
+  // Check for a DIV with the same operands as this REM.
+  for (auto UI : Op.getOperand(1)->uses()) {
+    if ((Op.getOpcode() == ISD::SREM && UI->getOpcode() == ISD::SDIV) ||
+        (Op.getOpcode() == ISD::UREM && UI->getOpcode() == ISD::UDIV))
+      if (UI->getOperand(0) == Op.getOperand(0) &&
+          UI->getOperand(1) == Op.getOperand(1))
+        return SDValue();
+  }
+  return Op;
+}
+
 SDValue PPCTargetLowering::LowerSIGN_EXTEND_INREG(SDValue Op,
                                                   SelectionDAG &DAG) const {
   SDLoc dl(Op);
@@ -8862,6 +8886,9 @@ SDValue PPCTargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
 
   case ISD::INTRINSIC_VOID:
     return LowerINTRINSIC_VOID(Op, DAG);
+  case ISD::SREM:
+  case ISD::UREM:
+    return LowerREM(Op, DAG);
   }
 }