Lower add (mul a, b), c into MACCU / MACCS nodes which translate

directly to the maccu / maccs instructions. We handle this in
ExpandADDSUB since after type legalisation it is messy to
recognise these operations.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98150 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 86 insertions, 0 deletions

diff --git a/lib/Target/XCore/XCoreISelDAGToDAG.cpp b/lib/Target/XCore/XCoreISelDAGToDAG.cpp
index b1ab132..12967d4 100644
--- a/lib/Target/XCore/XCoreISelDAGToDAG.cpp
+++ b/lib/Target/XCore/XCoreISelDAGToDAG.cpp
@@ -208,6 +208,18 @@ SDNode *XCoreDAGToDAGISel::Select(SDNode *N) {
         return CurDAG->getMachineNode(XCore::LSUB_l5r, dl, MVT::i32, MVT::i32,
                                       Ops, 3);
       }
+      case XCoreISD::MACCU: {
+        SDValue Ops[] = { N->getOperand(0), N->getOperand(1),
+                          N->getOperand(2), N->getOperand(3) };
+        return CurDAG->getMachineNode(XCore::MACCU_l4r, dl, MVT::i32, MVT::i32,
+                                      Ops, 4);
+      }
+      case XCoreISD::MACCS: {
+        SDValue Ops[] = { N->getOperand(0), N->getOperand(1),
+                          N->getOperand(2), N->getOperand(3) };
+        return CurDAG->getMachineNode(XCore::MACCS_l4r, dl, MVT::i32, MVT::i32,
+                                      Ops, 4);
+      }
       // Other cases are autogenerated.
     }
   }
diff --git a/lib/Target/XCore/XCoreISelLowering.cpp b/lib/Target/XCore/XCoreISelLowering.cpp
index 7ecd151..b59ed54 100644
--- a/lib/Target/XCore/XCoreISelLowering.cpp
+++ b/lib/Target/XCore/XCoreISelLowering.cpp
@@ -54,6 +54,8 @@ getTargetNodeName(unsigned Opcode) const
     case XCoreISD::RETSP             : return "XCoreISD::RETSP";
     case XCoreISD::LADD              : return "XCoreISD::LADD";
     case XCoreISD::LSUB              : return "XCoreISD::LSUB";
+    case XCoreISD::MACCU             : return "XCoreISD::MACCU";
+    case XCoreISD::MACCS             : return "XCoreISD::MACCS";
     case XCoreISD::BR_JT             : return "XCoreISD::BR_JT";
     case XCoreISD::BR_JT32           : return "XCoreISD::BR_JT32";
     default                           : return NULL;
@@ -542,11 +544,76 @@ LowerSTORE(SDValue Op, SelectionDAG &DAG)
 }
 
 SDValue XCoreTargetLowering::
+TryExpandADDSUBWithMul(SDNode *N, SelectionDAG &DAG)
+{
+  SDValue Mul;
+  SDValue Other;
+  if (N->getOperand(0).getOpcode() == ISD::MUL) {
+    Mul = N->getOperand(0);
+    Other = N->getOperand(1);
+  } else if (N->getOperand(1).getOpcode() == ISD::MUL) {
+    Mul = N->getOperand(1);
+    Other = N->getOperand(0);
+  } else {
+    return SDValue();
+  }
+  DebugLoc dl = N->getDebugLoc();
+  SDValue LL, RL, AddendL, AddendH;
+  LL = DAG.getNode(ISD::EXTRACT_ELEMENT, dl, MVT::i32,
+                   Mul.getOperand(0),  DAG.getConstant(0, MVT::i32));
+  RL = DAG.getNode(ISD::EXTRACT_ELEMENT, dl, MVT::i32,
+                   Mul.getOperand(1),  DAG.getConstant(0, MVT::i32));
+  AddendL = DAG.getNode(ISD::EXTRACT_ELEMENT, dl, MVT::i32,
+                        Other,  DAG.getConstant(0, MVT::i32));
+  AddendH = DAG.getNode(ISD::EXTRACT_ELEMENT, dl, MVT::i32,
+                        Other,  DAG.getConstant(1, MVT::i32));
+  APInt HighMask = APInt::getHighBitsSet(64, 32);
+  unsigned LHSSB = DAG.ComputeNumSignBits(Mul.getOperand(0));
+  unsigned RHSSB = DAG.ComputeNumSignBits(Mul.getOperand(1));
+  if (DAG.MaskedValueIsZero(Mul.getOperand(0), HighMask) &&
+      DAG.MaskedValueIsZero(Mul.getOperand(1), HighMask)) {
+    // The inputs are both zero-extended.
+    SDValue Hi = DAG.getNode(XCoreISD::MACCU, dl,
+                             DAG.getVTList(MVT::i32, MVT::i32), AddendH,
+                             AddendL, LL, RL);
+    SDValue Lo(Hi.getNode(), 1);
+    return DAG.getNode(ISD::BUILD_PAIR, dl, MVT::i64, Lo, Hi);
+  }
+  if (LHSSB > 32 && RHSSB > 32) {
+    // The inputs are both sign-extended.
+    SDValue Hi = DAG.getNode(XCoreISD::MACCS, dl,
+                             DAG.getVTList(MVT::i32, MVT::i32), AddendH,
+                             AddendL, LL, RL);
+    SDValue Lo(Hi.getNode(), 1);
+    return DAG.getNode(ISD::BUILD_PAIR, dl, MVT::i64, Lo, Hi);
+  }
+  SDValue LH, RH;
+  LH = DAG.getNode(ISD::EXTRACT_ELEMENT, dl, MVT::i32,
+                   Mul.getOperand(0),  DAG.getConstant(1, MVT::i32));
+  RH = DAG.getNode(ISD::EXTRACT_ELEMENT, dl, MVT::i32,
+                   Mul.getOperand(1),  DAG.getConstant(1, MVT::i32));
+  SDValue Hi = DAG.getNode(XCoreISD::MACCU, dl,
+                           DAG.getVTList(MVT::i32, MVT::i32), AddendH,
+                           AddendL, LL, RL);
+  SDValue Lo(Hi.getNode(), 1);
+  RH = DAG.getNode(ISD::MUL, dl, MVT::i32, LL, RH);
+  LH = DAG.getNode(ISD::MUL, dl, MVT::i32, LH, RL);
+  Hi = DAG.getNode(ISD::ADD, dl, MVT::i32, Hi, RH);
+  Hi = DAG.getNode(ISD::ADD, dl, MVT::i32, Hi, LH);
+  return DAG.getNode(ISD::BUILD_PAIR, dl, MVT::i64, Lo, Hi);
+}
+
+SDValue XCoreTargetLowering::
 ExpandADDSUB(SDNode *N, SelectionDAG &DAG)
 {
   assert(N->getValueType(0) == MVT::i64 &&
          (N->getOpcode() == ISD::ADD || N->getOpcode() == ISD::SUB) &&
         "Unknown operand to lower!");
+
+  SDValue Result = TryExpandADDSUBWithMul(N, DAG);
+  if (Result.getNode() != 0)
+    return Result;
+
   DebugLoc dl = N->getDebugLoc();
   
   // Extract components
diff --git a/lib/Target/XCore/XCoreISelLowering.h b/lib/Target/XCore/XCoreISelLowering.h
index f44c324..4013723 100644
--- a/lib/Target/XCore/XCoreISelLowering.h
+++ b/lib/Target/XCore/XCoreISelLowering.h
@@ -54,6 +54,12 @@ namespace llvm {
       // Corresponds to LSUB instruction
       LSUB,
 
+      // Corresponds to MACCU instruction
+      MACCU,
+
+      // Corresponds to MACCS instruction
+      MACCS,
+
       // Jumptable branch.
       BR_JT,
 
@@ -140,6 +146,7 @@ namespace llvm {
               EVT VT) const;
   
     // Expand specifics
+    SDValue TryExpandADDSUBWithMul(SDNode *Op, SelectionDAG &DAG);
     SDValue ExpandADDSUB(SDNode *Op, SelectionDAG &DAG);
 
     virtual SDValue PerformDAGCombine(SDNode *N, DAGCombinerInfo &DCI) const;