[mips] Remove custom versions of CCState::AnalyzeReturn() and CCState::AnalyzeCallReturn().

[dsanders]

Summary

The N32/N64 ABI's return f128 values in $f0 and $f2 for hard-float and $v0 and
$a0 for soft-float. The registers used in the soft-float case differ from the
usual $v0, and $v1 specified for return values.

Both cases were previously handled by duplicating the CCState::AnalyzeReturn()
and CCState::AnalyzeCallReturn() functions and modifying them to delegate to
a different assignment function for f128 and further replace the register type
for the hard-float case. There is a simpler way to do both of these.

We now use the common functions and select an initial assignment function based
on whether the original type is f128 or not. We then handle the hard-float case
using CCBitConvertToType<>.

No functional change.

[vmedic]

lib/Target/Mips/MipsISelLowering.cpp

2377

I don't see the implementation of this function, is that generated by tableGen?

[dsanders]

lib/Target/Mips/MipsISelLowering.cpp

2377

It's on line 3372. I've only moved the prototype so that I can use it from the tablegen-erated code.

[vmedic]

LGTM.

lib/Target/Mips/MipsISelLowering.cpp

2377

OK, sorry. I thought that the method is newly introduced and was confused since the diff didn't show the code for it.

lib/Target/Mips/MipsCallingConv.td

def RetCC_MipsN : CallingConv<[
 
   // f32 are returned in registers F0, F2
   CCIfType<[f32], CCAssignToReg<[F0, F2]>>,
 
   // f64 are returned in registers D0, D2
   CCIfType<[f64], CCAssignToReg<[D0_64, D2_64]>>
 ]>;
 
-// In soft-mode, register A0_64, instead of V1_64, is used to return a long
-// double value.
-def RetCC_F128Soft : CallingConv<[
-  CCIfType<[i64], CCAssignToReg<[V0_64, A0_64]>>
+// For soft-float, f128 values are returned in A0_64 rather than V1_64.
+def RetCC_F128SoftFloat : CallingConv<[
+  CCAssignToReg<[V0_64, A0_64]>
+]>;
+
+// For hard-float, f128 values are returned as a pair of f64's rather than a
+// pair of i64's.
+def RetCC_F128HardFloat : CallingConv<[
+  CCBitConvertToType<f64>,
+  CCAssignToReg<[D0_64, D2_64]>
+]>;
+
+// Handle F128 specially since we can't identify the original type during the
+// tablegen-erated code.
+def RetCC_F128 : CallingConv<[
+  CCIfSubtarget<"abiUsesSoftFloat()",
+      CCIfType<[i64], CCDelegateTo<RetCC_F128SoftFloat>>>,
+  CCIfNotSubtarget<"abiUsesSoftFloat()",
+      CCIfType<[i64], CCDelegateTo<RetCC_F128HardFloat>>>
 ]>;
 
 //===----------------------------------------------------------------------===//
 // Mips EABI Calling Convention
 //===----------------------------------------------------------------------===//
 
 def CC_MipsEABI : CallingConv<[
   // Promote i8/i16 arguments to i32.

lib/Target/Mips/MipsISelLowering.h

public:
       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);
 
-      void analyzeCallResult(const SmallVectorImpl<ISD::InputArg> &Ins,
-                             bool IsSoftFloat, const SDNode *CallNode,
-                             const Type *RetTy) const;
-
-      void analyzeReturn(const SmallVectorImpl<ISD::OutputArg> &Outs,
-                         bool IsSoftFloat, const Type *RetTy) const;
-
       const CCState &getCCInfo() const { return CCInfo; }
 
       /// hasByValArg - Returns true if function has byval arguments.
       bool hasByValArg() const { return !ByValArgs.empty(); }
 
       /// reservedArgArea - The size of the area the caller reserves for
       /// register arguments. This is 16-byte if ABI is O32.
       unsigned reservedArgArea() const;

lib/Target/Mips/MipsISelLowering.cpp

 static bool CC_MipsO32_FP64(unsigned ValNo, MVT ValVT,
                             MVT LocVT, CCValAssign::LocInfo LocInfo,
                             ISD::ArgFlagsTy ArgFlags, CCState &State) {
   static const MCPhysReg F64Regs[] = { Mips::D12_64, Mips::D14_64 };
 
   return CC_MipsO32(ValNo, ValVT, LocVT, LocInfo, ArgFlags, State, F64Regs);
 }
 
+static bool originalTypeIsF128(const Type *Ty, const SDNode *CallNode);
+
 #include "MipsGenCallingConv.inc"
 
 //===----------------------------------------------------------------------===//
 //                  Call Calling Convention Implementation
 //===----------------------------------------------------------------------===//
 
 // Return next O32 integer argument register.
 static unsigned getNextIntArgReg(unsigned Reg) {
MipsTargetLowering::LowerCallResult(SDValue Chain, SDValue InFlag,
                                     SDLoc DL, SelectionDAG &DAG,
                                     SmallVectorImpl<SDValue> &InVals,
                                     const SDNode *CallNode,
                                     const Type *RetTy) const {
   // Assign locations to each value returned by this call.
   SmallVector<CCValAssign, 16> RVLocs;
   CCState CCInfo(CallConv, IsVarArg, DAG.getMachineFunction(), RVLocs,
                  *DAG.getContext());
-  MipsCC MipsCCInfo(CallConv, Subtarget, CCInfo);
 
-  MipsCCInfo.analyzeCallResult(Ins, Subtarget.abiUsesSoftFloat(),
-                               CallNode, RetTy);
+  if (originalTypeIsF128(RetTy, CallNode))
+    CCInfo.AnalyzeCallResult(Ins, RetCC_F128);
+  else
+    CCInfo.AnalyzeCallResult(Ins, RetCC_Mips);
 
   // Copy all of the result registers out of their specified physreg.
   for (unsigned i = 0; i != RVLocs.size(); ++i) {
     SDValue Val = DAG.getCopyFromReg(Chain, DL, RVLocs[i].getLocReg(),
                                      RVLocs[i].getLocVT(), InFlag);
     Chain = Val.getValue(1);
     InFlag = Val.getValue(2);
 
MipsTargetLowering::LowerReturn(SDValue Chain,
   SmallVector<CCValAssign, 16> RVLocs;
   MachineFunction &MF = DAG.getMachineFunction();
 
   // CCState - Info about the registers and stack slot.
   CCState CCInfo(CallConv, IsVarArg, MF, RVLocs, *DAG.getContext());
   MipsCC MipsCCInfo(CallConv, Subtarget, CCInfo);
 
   // Analyze return values.
-  MipsCCInfo.analyzeReturn(Outs, Subtarget.abiUsesSoftFloat(),
-                           MF.getFunction()->getReturnType());
+  if (originalTypeIsF128(MF.getFunction()->getReturnType(), nullptr))
+    CCInfo.AnalyzeReturn(Outs, RetCC_F128);
+  else
+    CCInfo.AnalyzeReturn(Outs, RetCC_Mips);
 
   SDValue Flag;
   SmallVector<SDValue, 4> RetOps(1, Chain);
 
   // Copy the result values into the output registers.
   for (unsigned i = 0; i != RVLocs.size(); ++i) {
     SDValue Val = OutVals[i];
     CCValAssign &VA = RVLocs[i];

 #ifndef NDEBUG
     dbgs() << "Formal Arg #" << I << " has unhandled type "
            << EVT(ArgVT).getEVTString();
 #endif
     llvm_unreachable(nullptr);
   }
 }
 
-template<typename Ty>
-void MipsTargetLowering::MipsCC::
-analyzeReturn(const SmallVectorImpl<Ty> &RetVals, bool IsSoftFloat,
-              const SDNode *CallNode, const Type *RetTy) const {
-  CCAssignFn *Fn;
-
-  if (IsSoftFloat && originalTypeIsF128(RetTy, CallNode))
-    Fn = RetCC_F128Soft;
-  else
-    Fn = RetCC_Mips;
-
-  for (unsigned I = 0, E = RetVals.size(); I < E; ++I) {
-    MVT VT = RetVals[I].VT;
-    ISD::ArgFlagsTy Flags = RetVals[I].Flags;
-    MVT RegVT = this->getRegVT(VT, RetTy, CallNode, IsSoftFloat);
-
-    if (Fn(I, VT, RegVT, CCValAssign::Full, Flags, this->CCInfo)) {
-#ifndef NDEBUG
-      dbgs() << "Call result #" << I << " has unhandled type "
-             << EVT(VT).getEVTString() << '\n';
-#endif
-      llvm_unreachable(nullptr);
-    }
-  }
-}
-
-void MipsTargetLowering::MipsCC::
-analyzeCallResult(const SmallVectorImpl<ISD::InputArg> &Ins, bool IsSoftFloat,
-                  const SDNode *CallNode, const Type *RetTy) const {
-  analyzeReturn(Ins, IsSoftFloat, CallNode, RetTy);
-}
-
-void MipsTargetLowering::MipsCC::
-analyzeReturn(const SmallVectorImpl<ISD::OutputArg> &Outs, bool IsSoftFloat,
-              const Type *RetTy) const {
-  analyzeReturn(Outs, IsSoftFloat, nullptr, RetTy);
-}
-
 void MipsTargetLowering::MipsCC::handleByValArg(unsigned ValNo, MVT ValVT,
                                                 MVT LocVT,
                                                 CCValAssign::LocInfo LocInfo,
                                                 ISD::ArgFlagsTy ArgFlags) {
   assert(ArgFlags.getByValSize() && "Byval argument's size shouldn't be 0.");
 
   struct ByValArgInfo ByVal;
   unsigned RegSizeInBytes = Subtarget.getGPRSizeInBytes();