[PowerPC] Better lowering for add/or of a FrameIndex

[oota-llvm.git] / lib / Target / PowerPC / PPCISelDAGToDAG.cpp

diff --git a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index 48c0388ceaef06c0bc26e4e217b76b0ada489ce4..2e10fee3a938b6ab3037e2802b363663c82b1970 100644 (file)
--- a/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -112,6 +112,8 @@ namespace {
     /// base register.  Return the virtual register that holds this value.
     SDNode *getGlobalBaseReg();
 
+    SDNode *getFrameIndex(SDNode *SN, SDNode *N, unsigned Offset = 0);
+
     // Select - Convert the specified operand from a target-independent to a
     // target-specific node if it hasn't already been changed.
     SDNode *Select(SDNode *N) override;
@@ -373,6 +375,18 @@ static bool isOpcWithIntImmediate(SDNode *N, unsigned Opc, unsigned& Imm) {
          && isInt32Immediate(N->getOperand(1).getNode(), Imm);
 }
 
+SDNode *PPCDAGToDAGISel::getFrameIndex(SDNode *SN, SDNode *N, unsigned Offset) {
+  SDLoc dl(SN);
+  int FI = cast<FrameIndexSDNode>(N)->getIndex();
+  SDValue TFI = CurDAG->getTargetFrameIndex(FI, N->getValueType(0));
+  unsigned Opc = N->getValueType(0) == MVT::i32 ? PPC::ADDI : PPC::ADDI8;
+  if (SN->hasOneUse())
+    return CurDAG->SelectNodeTo(SN, Opc, N->getValueType(0), TFI,
+                                getSmallIPtrImm(Offset));
+  return CurDAG->getMachineNode(Opc, dl, N->getValueType(0), TFI,
+                                getSmallIPtrImm(Offset));
+}
+
 bool PPCDAGToDAGISel::isRunOfOnes(unsigned Val, unsigned &MB, unsigned &ME) {
   if (!Val)
     return false;
@@ -1019,16 +1033,8 @@ SDNode *PPCDAGToDAGISel::Select(SDNode *N) {
   case PPCISD::GlobalBaseReg:
     return getGlobalBaseReg();
 
-  case ISD::FrameIndex: {
-    int FI = cast<FrameIndexSDNode>(N)->getIndex();
-    SDValue TFI = CurDAG->getTargetFrameIndex(FI, N->getValueType(0));
-    unsigned Opc = N->getValueType(0) == MVT::i32 ? PPC::ADDI : PPC::ADDI8;
-    if (N->hasOneUse())
-      return CurDAG->SelectNodeTo(N, Opc, N->getValueType(0), TFI,
-                                  getSmallIPtrImm(0));
-    return CurDAG->getMachineNode(Opc, dl, N->getValueType(0), TFI,
-                                  getSmallIPtrImm(0));
-  }
+  case ISD::FrameIndex:
+    return getFrameIndex(N, N);
 
   case PPCISD::MFOCRF: {
     SDValue InFlag = N->getOperand(1);
@@ -1213,13 +1219,34 @@ SDNode *PPCDAGToDAGISel::Select(SDNode *N) {
     // Other cases are autogenerated.
     break;
   }
-  case ISD::OR:
+  case ISD::OR: {
     if (N->getValueType(0) == MVT::i32)
       if (SDNode *I = SelectBitfieldInsert(N))
         return I;
 
+    short Imm;
+    if (N->getOperand(0)->getOpcode() == ISD::FrameIndex &&
+        isIntS16Immediate(N->getOperand(1), Imm)) {
+      APInt LHSKnownZero, LHSKnownOne;
+      CurDAG->computeKnownBits(N->getOperand(0), LHSKnownZero, LHSKnownOne);
+
+      // If this is equivalent to an add, then we can fold it with the
+      // FrameIndex calculation.
+      if ((LHSKnownZero.getZExtValue()|~(uint64_t)Imm) == ~0ULL)
+        return getFrameIndex(N, N->getOperand(0).getNode(), (int)Imm);
+    }
+
     // Other cases are autogenerated.
     break;
+  }
+  case ISD::ADD: {
+    short Imm;
+    if (N->getOperand(0)->getOpcode() == ISD::FrameIndex &&
+        isIntS16Immediate(N->getOperand(1), Imm))
+      return getFrameIndex(N, N->getOperand(0).getNode(), (int)Imm);
+
+    break;
+  }
   case ISD::SHL: {
     unsigned Imm, SH, MB, ME;
     if (isOpcWithIntImmediate(N->getOperand(0).getNode(), ISD::AND, Imm) &&