[mips] Removed MipsCC::fixedArgFn(). NFC

[dsanders]

Summary

There is one remaining trace of it in MipsCC::analyzeCallOperands() where
Mips16 might override the calling convention. This will moved into
tablegen-erated code later.

Depends on D5965

[vmedic]

LGTM

lib/Target/Mips/MipsISelLowering.h

protected:
     /// arguments and inquire about calling convention information.
     class MipsCC {
     public:
       enum SpecialCallingConvType {
         Mips16RetHelperConv, NoSpecialCallingConv
       };
 
       MipsCC(CallingConv::ID CallConv, const MipsSubtarget &Subtarget,
-             CCState &Info,
-             SpecialCallingConvType SpecialCallingConv = NoSpecialCallingConv);
+             CCState &Info);
 
       void analyzeCallOperands(const SmallVectorImpl<ISD::OutputArg> &Outs,
                                bool IsVarArg, bool IsSoftFloat,
                                const SDNode *CallNode,
                                std::vector<ArgListEntry> &FuncArgs);
       void analyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> &Ins,
                                   bool IsSoftFloat,
                                   Function::const_arg_iterator FuncArg);
private:
       void handleByValArg(unsigned ValNo, MVT ValVT, MVT LocVT,
                           CCValAssign::LocInfo LocInfo,
                           ISD::ArgFlagsTy ArgFlags);
 
       /// useRegsForByval - Returns true if the calling convention allows the
       /// use of registers to pass byval arguments.
       bool useRegsForByval() const { return CallConv != CallingConv::Fast; }
 
-      /// Return the function that analyzes fixed argument list functions.
-      llvm::CCAssignFn *fixedArgFn() const;
-
       const MCPhysReg *shadowRegs() const;
 
       void allocateRegs(ByValArgInfo &ByVal, unsigned ByValSize,
                         unsigned Align);
 
       /// Return the type of the register which is used to pass an argument or
       /// return a value. This function returns f64 if the argument is an i64
       /// value which has been generated as a result of softening an f128 value.
       /// Otherwise, it just returns VT.
       MVT getRegVT(MVT VT, const Type *OrigTy, const SDNode *CallNode,
                    bool IsSoftFloat) const;
 
+      SpecialCallingConvType getSpecialCallingConv(const SDNode *Callee) const;
+
       CCState &CCInfo;
       CallingConv::ID CallConv;
       const MipsSubtarget &Subtarget;
-      SpecialCallingConvType SpecialCallingConv;
       SmallVector<ByValArgInfo, 2> ByValArgs;
     };
   protected:
     SDValue lowerLOAD(SDValue Op, SelectionDAG &DAG) const;
     SDValue lowerSTORE(SDValue Op, SelectionDAG &DAG) const;
 
     // Subtarget Info
     const MipsSubtarget &Subtarget;
private:
     // Create a TargetJumpTable node.
     SDValue getTargetNode(JumpTableSDNode *N, EVT Ty, SelectionDAG &DAG,
                           unsigned Flag) const;
 
     // Create a TargetConstantPool node.
     SDValue getTargetNode(ConstantPoolSDNode *N, EVT Ty, SelectionDAG &DAG,
                           unsigned Flag) const;
 
-    MipsCC::SpecialCallingConvType getSpecialCallingConv(SDValue Callee) const;
-
     // Lower Operand helpers
     SDValue LowerCallResult(SDValue Chain, SDValue InFlag,
                             CallingConv::ID CallConv, bool isVarArg,
                             const SmallVectorImpl<ISD::InputArg> &Ins, SDLoc dl,
                             SelectionDAG &DAG, SmallVectorImpl<SDValue> &InVals,
                             TargetLowering::CallLoweringInfo &CLI) const;
 
     // Lower Operand specifics

lib/Target/Mips/MipsISelLowering.cpp

MipsTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
   const TargetFrameLowering *TFL = MF.getSubtarget().getFrameLowering();
   MipsFunctionInfo *FuncInfo = MF.getInfo<MipsFunctionInfo>();
   bool IsPIC = getTargetMachine().getRelocationModel() == Reloc::PIC_;
 
   // Analyze operands of the call, assigning locations to each operand.
   SmallVector<CCValAssign, 16> ArgLocs;
   CCState CCInfo(CallConv, IsVarArg, DAG.getMachineFunction(), ArgLocs,
                  *DAG.getContext());
-  MipsCC::SpecialCallingConvType SpecialCallingConv =
-    getSpecialCallingConv(Callee);
-  MipsCC MipsCCInfo(CallConv, Subtarget, CCInfo, SpecialCallingConv);
+  MipsCC MipsCCInfo(CallConv, Subtarget, CCInfo);
 
   MipsCCInfo.analyzeCallOperands(Outs, IsVarArg,
                                  Subtarget.abiUsesSoftFloat(),
                                  Callee.getNode(), CLI.getArgs());
 
   // Get a count of how many bytes are to be pushed on the stack.
   unsigned NextStackOffset = CCInfo.getNextStackOffset();
 
const ExternalSymbolSDNode *ES =
     dyn_cast_or_null<const ExternalSymbolSDNode>(CallNode);
 
   // If the Ty is i128 and the function being called is a long double emulation
   // routine, then the original type is f128.
   return (ES && Ty->isIntegerTy(128) && isF128SoftLibCall(ES->getSymbol()));
 }
 
 MipsTargetLowering::MipsCC::SpecialCallingConvType
-  MipsTargetLowering::getSpecialCallingConv(SDValue Callee) const {
+MipsTargetLowering::MipsCC::getSpecialCallingConv(const SDNode *Callee) const {
   MipsCC::SpecialCallingConvType SpecialCallingConv =
     MipsCC::NoSpecialCallingConv;
   if (Subtarget.inMips16HardFloat()) {
-    if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
+    if (const GlobalAddressSDNode *G =
+            dyn_cast<const GlobalAddressSDNode>(Callee)) {
       llvm::StringRef Sym = G->getGlobal()->getName();
       Function *F = G->getGlobal()->getParent()->getFunction(Sym);
       if (F && F->hasFnAttribute("__Mips16RetHelper")) {
         SpecialCallingConv = MipsCC::Mips16RetHelperConv;
       }
     }
   }
   return SpecialCallingConv;
 }
 
-MipsTargetLowering::MipsCC::MipsCC(
-    CallingConv::ID CC, const MipsSubtarget &Subtarget_, CCState &Info,
-    MipsCC::SpecialCallingConvType SpecialCallingConv_)
-    : CCInfo(Info), CallConv(CC), Subtarget(Subtarget_),
-      SpecialCallingConv(SpecialCallingConv_) {
+MipsTargetLowering::MipsCC::MipsCC(CallingConv::ID CC,
+                                   const MipsSubtarget &Subtarget_,
+                                   CCState &Info)
+    : CCInfo(Info), CallConv(CC), Subtarget(Subtarget_) {
   // Pre-allocate reserved argument area.
   CCInfo.AllocateStack(reservedArgArea(), 1);
 }
 
 
 void MipsTargetLowering::MipsCC::
 analyzeCallOperands(const SmallVectorImpl<ISD::OutputArg> &Args,
                     bool IsVarArg, bool IsSoftFloat, const SDNode *CallNode,
                     std::vector<ArgListEntry> &FuncArgs) {
+  MipsCC::SpecialCallingConvType SpecialCallingConv =
+      getSpecialCallingConv(CallNode);
   assert((CallConv != CallingConv::Fast || !IsVarArg) &&
          "CallingConv::Fast shouldn't be used for vararg functions.");
 
   unsigned NumOpnds = Args.size();
-  llvm::CCAssignFn *FixedFn = fixedArgFn();
+  llvm::CCAssignFn *FixedFn = CC_Mips_FixedArg;
+  if (CallConv != CallingConv::Fast &&
+      SpecialCallingConv == Mips16RetHelperConv)
+    FixedFn = CC_Mips16RetHelper;
 
   for (unsigned I = 0; I != NumOpnds; ++I) {
     MVT ArgVT = Args[I].VT;
     ISD::ArgFlagsTy ArgFlags = Args[I].Flags;
     bool R;
 
     if (ArgFlags.isByVal()) {
       handleByValArg(I, ArgVT, ArgVT, CCValAssign::Full, ArgFlags);
#endif
     }
   }
 }
 
 void MipsTargetLowering::MipsCC::
 analyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> &Args,
                        bool IsSoftFloat, Function::const_arg_iterator FuncArg) {
   unsigned NumArgs = Args.size();
-  llvm::CCAssignFn *FixedFn = fixedArgFn();
   unsigned CurArgIdx = 0;
 
   for (unsigned I = 0; I != NumArgs; ++I) {
     MVT ArgVT = Args[I].VT;
     ISD::ArgFlagsTy ArgFlags = Args[I].Flags;
     std::advance(FuncArg, Args[I].OrigArgIndex - CurArgIdx);
     CurArgIdx = Args[I].OrigArgIndex;
 
     if (ArgFlags.isByVal()) {
       handleByValArg(I, ArgVT, ArgVT, CCValAssign::Full, ArgFlags);
       continue;
     }
 
     MVT RegVT = getRegVT(ArgVT, FuncArg->getType(), nullptr, IsSoftFloat);
 
-    if (!FixedFn(I, ArgVT, RegVT, CCValAssign::Full, ArgFlags, CCInfo))
+    if (!CC_Mips_FixedArg(I, ArgVT, RegVT, CCValAssign::Full, ArgFlags, CCInfo))
       continue;
 
 #ifndef NDEBUG
     dbgs() << "Formal Arg #" << I << " has unhandled type "
            << EVT(ArgVT).getEVTString();
 #endif
     llvm_unreachable(nullptr);
   }

 }
 
 const ArrayRef<MCPhysReg> MipsTargetLowering::MipsCC::intArgRegs() const {
   if (Subtarget.isABI_O32())
     return makeArrayRef(O32IntRegs);
   return makeArrayRef(Mips64IntRegs);
 }
 
-llvm::CCAssignFn *MipsTargetLowering::MipsCC::fixedArgFn() const {
-  if (CallConv != CallingConv::Fast &&
-      SpecialCallingConv == Mips16RetHelperConv)
-    return CC_Mips16RetHelper;
-
-  return CC_Mips_FixedArg;
-}
-
 const MCPhysReg *MipsTargetLowering::MipsCC::shadowRegs() const {
   return Subtarget.isABI_O32() ? O32IntRegs : Mips64DPRegs;
 }
 
 void MipsTargetLowering::MipsCC::allocateRegs(ByValArgInfo &ByVal,
                                               unsigned ByValSize,
                                               unsigned Align) {
   unsigned RegSizeInBytes = Subtarget.getGPRSizeInBytes();