Revert the SelectionDAG optimization that makes
it impossible to create a MERGE_VALUES node with
only one result: sometimes it is useful to be able
to create a node with only one result out of one of
the results of a node with more than one result, for
example because the new node will eventually be used
to replace a one-result node using ReplaceAllUsesWith,
cf X86TargetLowering::ExpandFP_TO_SINT.  On the other
hand, most users of MERGE_VALUES don't need this and
for them the optimization was valuable.  So add a new
utility method getMergeValues for creating MERGE_VALUES
nodes which by default performs the optimization.
Change almost everywhere to use getMergeValues (and
tidy some stuff up at the same time).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52893 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index cfb98cb..2c11919 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -654,8 +654,8 @@
     return Chain;
 
   ResultVals.push_back(Chain);
-  SDOperand Res = DAG.getNode(ISD::MERGE_VALUES, NodeTys, &ResultVals[0],
-                              ResultVals.size());
+  SDOperand Res = DAG.getMergeValues(DAG.getVTList(&NodeTys[0], NodeTys.size()),
+                                     &ResultVals[0], ResultVals.size());
   return Res.getValue(Op.ResNo);
 }
 
@@ -1025,9 +1025,8 @@
   ArgValues.push_back(Root);
 
   // Return the new list of results.
-  std::vector<MVT> RetVT(Op.Val->value_begin(),
-                                    Op.Val->value_end());
-  return DAG.getNode(ISD::MERGE_VALUES, RetVT, &ArgValues[0], ArgValues.size());
+  return DAG.getMergeValues(Op.Val->getVTList(), &ArgValues[0],
+                            ArgValues.size());
 }
 
 /// isFloatingPointZero - Return true if this is +0.0.
diff --git a/lib/Target/Alpha/AlphaISelLowering.cpp b/lib/Target/Alpha/AlphaISelLowering.cpp
index dd001b4..ad50816 100644
--- a/lib/Target/Alpha/AlphaISelLowering.cpp
+++ b/lib/Target/Alpha/AlphaISelLowering.cpp
@@ -280,9 +280,8 @@
   ArgValues.push_back(Root);
 
   // Return the new list of results.
-  std::vector<MVT> RetVT(Op.Val->value_begin(),
-                                    Op.Val->value_end());
-  return DAG.getNode(ISD::MERGE_VALUES, RetVT, &ArgValues[0], ArgValues.size());
+  return DAG.getMergeValues(Op.Val->getVTList(), &ArgValues[0],
+                            ArgValues.size());
 }
 
 static SDOperand LowerRET(SDOperand Op, SelectionDAG &DAG) {
diff --git a/lib/Target/CellSPU/SPUISelLowering.cpp b/lib/Target/CellSPU/SPUISelLowering.cpp
index 41555c0..e99a8bd 100644
--- a/lib/Target/CellSPU/SPUISelLowering.cpp
+++ b/lib/Target/CellSPU/SPUISelLowering.cpp
@@ -1060,9 +1060,8 @@
   ArgValues.push_back(Root);
  
   // Return the new list of results.
-  std::vector<MVT> RetVT(Op.Val->value_begin(),
-                                    Op.Val->value_end());
-  return DAG.getNode(ISD::MERGE_VALUES, RetVT, &ArgValues[0], ArgValues.size());
+  return DAG.getMergeValues(Op.Val->getVTList(), &ArgValues[0],
+                            ArgValues.size());
 }
 
 /// isLSAAddress - Return the immediate to use if the specified
@@ -1301,8 +1300,8 @@
   
   // Otherwise, merge everything together with a MERGE_VALUES node.
   ResultVals[NumResults++] = Chain;
-  SDOperand Res = DAG.getNode(ISD::MERGE_VALUES, NodeTys,
-                              ResultVals, NumResults);
+  SDOperand Res = DAG.getMergeValues(DAG.getVTList(&NodeTys[0], NodeTys.size()),
+                                     ResultVals, NumResults);
   return Res.getValue(Op.ResNo);
 }
 
diff --git a/lib/Target/Mips/MipsISelLowering.cpp b/lib/Target/Mips/MipsISelLowering.cpp
index 16464d1..3dfd334 100644
--- a/lib/Target/Mips/MipsISelLowering.cpp
+++ b/lib/Target/Mips/MipsISelLowering.cpp
@@ -517,8 +517,8 @@
   ResultVals.push_back(Chain);
 
   // Merge everything together with a MERGE_VALUES node.
-  return DAG.getNode(ISD::MERGE_VALUES, TheCall->getVTList(),
-                     &ResultVals[0], ResultVals.size()).Val;                       
+  return DAG.getMergeValues(TheCall->getVTList(), &ResultVals[0],
+                            ResultVals.size()).Val;
 }
 
 //===----------------------------------------------------------------------===//
@@ -649,8 +649,8 @@
   ArgValues.push_back(Root);
 
   // Return the new list of results.
-  return DAG.getNode(ISD::MERGE_VALUES, Op.Val->getVTList(),
-                     &ArgValues[0], ArgValues.size()).getValue(Op.ResNo);
+  return DAG.getMergeValues(Op.Val->getVTList(), &ArgValues[0],
+                            ArgValues.size()).getValue(Op.ResNo);
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/lib/Target/PIC16/PIC16ISelLowering.cpp b/lib/Target/PIC16/PIC16ISelLowering.cpp
index deab5d5..fa1698f 100644
--- a/lib/Target/PIC16/PIC16ISelLowering.cpp
+++ b/lib/Target/PIC16/PIC16ISelLowering.cpp
@@ -542,8 +542,8 @@
   // FIXME: Just copy right now.
   ArgValues.push_back(Root);
 
-  return DAG.getNode(ISD::MERGE_VALUES, Op.Val->getVTList(), &ArgValues[0], 
-                     ArgValues.size()).getValue(Op.ResNo);
+  return DAG.getMergeValues(Op.Val->getVTList(), &ArgValues[0],
+                            ArgValues.size()).getValue(Op.ResNo);
 }
 
 
diff --git a/lib/Target/PowerPC/PPCISelLowering.cpp b/lib/Target/PowerPC/PPCISelLowering.cpp
index 9432a74..918db9d 100644
--- a/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -1775,9 +1775,8 @@
   ArgValues.push_back(Root);
  
   // Return the new list of results.
-  std::vector<MVT> RetVT(Op.Val->value_begin(),
-                                    Op.Val->value_end());
-  return DAG.getNode(ISD::MERGE_VALUES, RetVT, &ArgValues[0], ArgValues.size());
+  return DAG.getMergeValues(Op.Val->getVTList(), &ArgValues[0],
+                            ArgValues.size());
 }
 
 /// CalculateParameterAndLinkageAreaSize - Get the size of the paramter plus
@@ -2557,8 +2556,8 @@
   
   // Otherwise, merge everything together with a MERGE_VALUES node.
   ResultVals.push_back(Chain);
-  SDOperand Res = DAG.getNode(ISD::MERGE_VALUES, Op.Val->getVTList(),
-                              &ResultVals[0], ResultVals.size());
+  SDOperand Res = DAG.getMergeValues(Op.Val->getVTList(), &ResultVals[0],
+                                     ResultVals.size());
   return Res.getValue(Op.ResNo);
 }
 
@@ -2753,8 +2752,7 @@
   };
   SDOperand Store = DAG.getNode(PPCISD::STCX, MVT::Other, Ops2, 4);
   SDOperand OutOps[] = { Load, Store };
-  return DAG.getNode(ISD::MERGE_VALUES, DAG.getVTList(VT, MVT::Other),
-                     OutOps, 2);
+  return DAG.getMergeValues(DAG.getVTList(VT, MVT::Other), OutOps, 2);
 }
 
 SDOperand PPCTargetLowering::LowerAtomicCMP_SWAP(SDOperand Op, SelectionDAG &DAG) {
@@ -2796,8 +2794,7 @@
   };
   SDOperand Store = DAG.getNode(PPCISD::STCX, MVT::Other, Ops3, 4);
   SDOperand OutOps[] = { Load, Store };
-  return DAG.getNode(ISD::MERGE_VALUES, DAG.getVTList(VT, MVT::Other),
-                     OutOps, 2);
+  return DAG.getMergeValues(DAG.getVTList(VT, MVT::Other), OutOps, 2);
 }
 
 SDOperand PPCTargetLowering::LowerAtomicSWAP(SDOperand Op, SelectionDAG &DAG) {
@@ -2829,8 +2826,7 @@
   };
   SDOperand Store = DAG.getNode(PPCISD::STCX, MVT::Other, Ops2, 4);
   SDOperand OutOps[] = { Load, Store };
-  return DAG.getNode(ISD::MERGE_VALUES, DAG.getVTList(VT, MVT::Other),
-                     OutOps, 2);
+  return DAG.getMergeValues(DAG.getVTList(VT, MVT::Other), OutOps, 2);
 }
 
 /// LowerSELECT_CC - Lower floating point select_cc's into fsel instruction when
@@ -3134,8 +3130,7 @@
   SDOperand OutHi = DAG.getNode(ISD::OR, VT, Tmp4, Tmp6);
   SDOperand OutLo = DAG.getNode(PPCISD::SHL, VT, Lo, Amt);
   SDOperand OutOps[] = { OutLo, OutHi };
-  return DAG.getNode(ISD::MERGE_VALUES, DAG.getVTList(VT, VT),
-                     OutOps, 2);
+  return DAG.getMergeValues(DAG.getVTList(VT, VT), OutOps, 2);
 }
 
 SDOperand PPCTargetLowering::LowerSRL_PARTS(SDOperand Op, SelectionDAG &DAG) {
@@ -3163,8 +3158,7 @@
   SDOperand OutLo = DAG.getNode(ISD::OR, VT, Tmp4, Tmp6);
   SDOperand OutHi = DAG.getNode(PPCISD::SRL, VT, Hi, Amt);
   SDOperand OutOps[] = { OutLo, OutHi };
-  return DAG.getNode(ISD::MERGE_VALUES, DAG.getVTList(VT, VT),
-                     OutOps, 2);
+  return DAG.getMergeValues(DAG.getVTList(VT, VT), OutOps, 2);
 }
 
 SDOperand PPCTargetLowering::LowerSRA_PARTS(SDOperand Op, SelectionDAG &DAG) {
@@ -3192,8 +3186,7 @@
   SDOperand OutLo = DAG.getSelectCC(Tmp5, DAG.getConstant(0, AmtVT),
                                     Tmp4, Tmp6, ISD::SETLE);
   SDOperand OutOps[] = { OutLo, OutHi };
-  return DAG.getNode(ISD::MERGE_VALUES, DAG.getVTList(VT, VT),
-                     OutOps, 2);
+  return DAG.getMergeValues(DAG.getVTList(VT, VT), OutOps, 2);
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/lib/Target/Sparc/SparcISelLowering.cpp b/lib/Target/Sparc/SparcISelLowering.cpp
index 5c06174..48b4fec 100644
--- a/lib/Target/Sparc/SparcISelLowering.cpp
+++ b/lib/Target/Sparc/SparcISelLowering.cpp
@@ -450,8 +450,8 @@
   ResultVals.push_back(Chain);
   
   // Merge everything together with a MERGE_VALUES node.
-  return DAG.getNode(ISD::MERGE_VALUES, Op.Val->getVTList(),
-                     &ResultVals[0], ResultVals.size());
+  return DAG.getMergeValues(Op.Val->getVTList(), &ResultVals[0],
+                            ResultVals.size());
 }
 
 
@@ -829,8 +829,7 @@
     DAG.getNode(ISD::BIT_CONVERT, MVT::f64, V),
     V.getValue(1)
   };
-  return DAG.getNode(ISD::MERGE_VALUES, DAG.getVTList(MVT::f64, MVT::Other),
-                     Ops, 2);
+  return DAG.getMergeValues(DAG.getVTList(MVT::f64, MVT::Other), Ops, 2);
 }
 
 static SDOperand LowerDYNAMIC_STACKALLOC(SDOperand Op, SelectionDAG &DAG) {
@@ -846,11 +845,8 @@
   // to provide a register spill area.
   SDOperand NewVal = DAG.getNode(ISD::ADD, MVT::i32, NewSP,
                                  DAG.getConstant(96, MVT::i32));
-  std::vector<MVT> Tys;
-  Tys.push_back(MVT::i32);
-  Tys.push_back(MVT::Other);
   SDOperand Ops[2] = { NewVal, Chain };
-  return DAG.getNode(ISD::MERGE_VALUES, Tys, Ops, 2);
+  return DAG.getMergeValues(DAG.getVTList(MVT::i32, MVT::Other), Ops, 2);
 }
 
 
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index bc7a4ae..7173df6 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -979,8 +979,8 @@
   
   // Merge everything together with a MERGE_VALUES node.
   ResultVals.push_back(Chain);
-  return DAG.getNode(ISD::MERGE_VALUES, TheCall->getVTList(),
-                     &ResultVals[0], ResultVals.size()).Val;
+  return DAG.getMergeValues(TheCall->getVTList(), &ResultVals[0],
+                            ResultVals.size()).Val;
 }
 
 
@@ -1377,8 +1377,8 @@
   FuncInfo->setBytesToPopOnReturn(BytesToPopOnReturn);
 
   // Return the new list of results.
-  return DAG.getNode(ISD::MERGE_VALUES, Op.Val->getVTList(),
-                     &ArgValues[0], ArgValues.size()).getValue(Op.ResNo);
+  return DAG.getMergeValues(Op.Val->getVTList(), &ArgValues[0],
+                            ArgValues.size()).getValue(Op.ResNo);
 }
 
 SDOperand
@@ -4361,7 +4361,6 @@
     Tmp3 = DAG.getNode(isSRA ? ISD::SRA : ISD::SRL, VT, ShOpHi, ShAmt);
   }
 
-  const MVT *VTs = DAG.getNodeValueTypes(MVT::Other, MVT::Flag);
   SDOperand AndNode = DAG.getNode(ISD::AND, MVT::i8, ShAmt,
                                   DAG.getConstant(VTBits, MVT::i8));
   SDOperand Cond = DAG.getNode(X86ISD::CMP, VT,
@@ -4369,41 +4368,19 @@
 
   SDOperand Hi, Lo;
   SDOperand CC = DAG.getConstant(X86::COND_NE, MVT::i8);
-  VTs = DAG.getNodeValueTypes(VT, MVT::Flag);
-  SmallVector<SDOperand, 4> Ops;
+  SDOperand Ops0[4] = { Tmp2, Tmp3, CC, Cond };
+  SDOperand Ops1[4] = { Tmp3, Tmp1, CC, Cond };
+
   if (Op.getOpcode() == ISD::SHL_PARTS) {
-    Ops.push_back(Tmp2);
-    Ops.push_back(Tmp3);
-    Ops.push_back(CC);
-    Ops.push_back(Cond);
-    Hi = DAG.getNode(X86ISD::CMOV, VT, &Ops[0], Ops.size());
-
-    Ops.clear();
-    Ops.push_back(Tmp3);
-    Ops.push_back(Tmp1);
-    Ops.push_back(CC);
-    Ops.push_back(Cond);
-    Lo = DAG.getNode(X86ISD::CMOV, VT, &Ops[0], Ops.size());
+    Hi = DAG.getNode(X86ISD::CMOV, VT, Ops0, 4);
+    Lo = DAG.getNode(X86ISD::CMOV, VT, Ops1, 4);
   } else {
-    Ops.push_back(Tmp2);
-    Ops.push_back(Tmp3);
-    Ops.push_back(CC);
-    Ops.push_back(Cond);
-    Lo = DAG.getNode(X86ISD::CMOV, VT, &Ops[0], Ops.size());
-
-    Ops.clear();
-    Ops.push_back(Tmp3);
-    Ops.push_back(Tmp1);
-    Ops.push_back(CC);
-    Ops.push_back(Cond);
-    Hi = DAG.getNode(X86ISD::CMOV, VT, &Ops[0], Ops.size());
+    Lo = DAG.getNode(X86ISD::CMOV, VT, Ops0, 4);
+    Hi = DAG.getNode(X86ISD::CMOV, VT, Ops1, 4);
   }
 
-  VTs = DAG.getNodeValueTypes(VT, VT);
-  Ops.clear();
-  Ops.push_back(Lo);
-  Ops.push_back(Hi);
-  return DAG.getNode(ISD::MERGE_VALUES, VTs, 2, &Ops[0], Ops.size());
+  SDOperand Ops[2] = { Lo, Hi };
+  return DAG.getMergeValues(DAG.getVTList(VT, VT), Ops, 2);
 }
 
 SDOperand X86TargetLowering::LowerSINT_TO_FP(SDOperand Op, SelectionDAG &DAG) {
@@ -4531,13 +4508,15 @@
   std::pair<SDOperand,SDOperand> Vals = FP_TO_SINTHelper(SDOperand(N, 0), DAG);
   SDOperand FIST = Vals.first, StackSlot = Vals.second;
   if (FIST.Val == 0) return 0;
-  
-  // Return an i64 load from the stack slot.
-  SDOperand Res = DAG.getLoad(MVT::i64, FIST, StackSlot, NULL, 0);
+
+  MVT VT = N->getValueType(0);
+
+  // Return a load from the stack slot.
+  SDOperand Res = DAG.getLoad(VT, FIST, StackSlot, NULL, 0);
 
   // Use a MERGE_VALUES node to drop the chain result value.
-  return DAG.getNode(ISD::MERGE_VALUES, MVT::i64, Res).Val;
-}  
+  return DAG.getMergeValues(DAG.getVTList(VT), &Res, 1, false).Val;
+}
 
 SDOperand X86TargetLowering::LowerFABS(SDOperand Op, SelectionDAG &DAG) {
   MVT VT = Op.getValueType();
@@ -4833,11 +4812,8 @@
 
   Chain = DAG.getCopyFromReg(Chain, X86StackPtr, SPTy).getValue(1);
 
-  std::vector<MVT> Tys;
-  Tys.push_back(SPTy);
-  Tys.push_back(MVT::Other);
   SDOperand Ops1[2] = { Chain.getValue(0), Chain };
-  return DAG.getNode(ISD::MERGE_VALUES, Tys, Ops1, 2);
+  return DAG.getMergeValues(DAG.getVTList(SPTy, MVT::Other), Ops1, 2);
 }
 
 SDOperand
@@ -5069,7 +5045,7 @@
     };
     
     Tys = DAG.getVTList(MVT::i64, MVT::Other);
-    return DAG.getNode(ISD::MERGE_VALUES, Tys, Ops, 2).Val;
+    return DAG.getMergeValues(Tys, Ops, 2).Val;
   }
   
   SDOperand eax = DAG.getCopyFromReg(rd, X86::EAX, MVT::i32, rd.getValue(1));
@@ -5081,8 +5057,7 @@
 
   // Use a MERGE_VALUES to return the value and chain.
   Ops[1] = edx.getValue(1);
-  Tys = DAG.getVTList(MVT::i64, MVT::Other);
-  return DAG.getNode(ISD::MERGE_VALUES, Tys, Ops, 2).Val;
+  return DAG.getMergeValues(DAG.getVTList(MVT::i64, MVT::Other), Ops, 2).Val;
 }
 
 SDOperand X86TargetLowering::LowerVASTART(SDOperand Op, SelectionDAG &DAG) {
@@ -5463,7 +5438,7 @@
 
     SDOperand Ops[] =
       { Trmp, DAG.getNode(ISD::TokenFactor, MVT::Other, OutChains, 6) };
-    return DAG.getNode(ISD::MERGE_VALUES, Op.Val->getVTList(), Ops, 2);
+    return DAG.getMergeValues(Op.Val->getVTList(), Ops, 2);
   } else {
     const Function *Func =
       cast<Function>(cast<SrcValueSDNode>(Op.getOperand(5))->getValue());
@@ -5531,7 +5506,7 @@
 
     SDOperand Ops[] =
       { Trmp, DAG.getNode(ISD::TokenFactor, MVT::Other, OutChains, 4) };
-    return DAG.getNode(ISD::MERGE_VALUES, Op.Val->getVTList(), Ops, 2);
+    return DAG.getMergeValues(Op.Val->getVTList(), Ops, 2);
   }
 }
 
@@ -5718,8 +5693,8 @@
                                         cpOutL.getValue(2));
   SDOperand OpsF[] = { cpOutL.getValue(0), cpOutH.getValue(0)};
   SDOperand ResultVal = DAG.getNode(ISD::BUILD_PAIR, MVT::i64, OpsF, 2);
-  Tys = DAG.getVTList(MVT::i64, MVT::Other);
-  return DAG.getNode(ISD::MERGE_VALUES, Tys, ResultVal, cpOutH.getValue(1)).Val;
+  SDOperand Vals[2] = { ResultVal, cpOutH.getValue(1) };
+  return DAG.getMergeValues(DAG.getVTList(MVT::i64, MVT::Other), Vals, 2).Val;
 }
 
 SDNode* X86TargetLowering::ExpandATOMIC_LOAD_SUB(SDNode* Op, SelectionDAG &DAG) {