Revert r221056 and others, "[mips] Move F128 argument handling into MipsCCState as we did for returns. NFC."

  r221056 "[mips] Move F128 argument handling into MipsCCState as we did for returns. NFC."
  r221058 "[mips] Fix unused variable warning introduced in r221056"
  r221059 "[mips] Move all ByVal handling into CCState and tablegen-erated code. NFC."
  r221061 "Renamed CCState members that appear to misspell 'Processed' as 'Proceed'. NFC."

It cuased an undefined behavior in LLVM :: CodeGen/Mips/return-vector.ll.

llvm-svn: 221081
diff --git a/llvm/lib/Target/Mips/MipsISelLowering.h b/llvm/lib/Target/Mips/MipsISelLowering.h
index 9fae7af..ba73085 100644
--- a/llvm/lib/Target/Mips/MipsISelLowering.h
+++ b/llvm/lib/Target/Mips/MipsISelLowering.h
@@ -259,8 +259,6 @@
       }
     };
 
-    void HandleByVal(CCState *, unsigned &, unsigned) const override;
-
   protected:
     SDValue getGlobalReg(SelectionDAG &DAG, EVT Ty) const;
 
@@ -341,6 +339,14 @@
                 bool IsCallReloc, CallLoweringInfo &CLI, SDValue Callee,
                 SDValue Chain) const;
 
+    /// ByValArgInfo - Byval argument information.
+    struct ByValArgInfo {
+      unsigned FirstIdx; // Index of the first register used.
+      unsigned NumRegs;  // Number of registers used for this argument.
+
+      ByValArgInfo() : FirstIdx(0), NumRegs(0) {}
+    };
+
     /// MipsCC - This class provides methods used to analyze formal and call
     /// arguments and inquire about calling convention information.
     class MipsCC {
@@ -359,8 +365,12 @@
                                CCState &State);
       void analyzeFormalArguments(const SmallVectorImpl<ISD::InputArg> &Ins,
                                   bool IsSoftFloat,
+                                  Function::const_arg_iterator FuncArg,
                                   CCState &State);
 
+      /// 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;
@@ -368,7 +378,24 @@
       /// Return pointer to array of integer argument registers.
       const ArrayRef<MCPhysReg> intArgRegs() const;
 
+      typedef SmallVectorImpl<ByValArgInfo>::const_iterator byval_iterator;
+      byval_iterator byval_begin() const { return ByValArgs.begin(); }
+      byval_iterator byval_end() const { return ByValArgs.end(); }
+
     private:
+      void handleByValArg(unsigned ValNo, MVT ValVT, MVT LocVT,
+                          CCValAssign::LocInfo LocInfo,
+                          ISD::ArgFlagsTy ArgFlags, CCState &State);
+
+      /// useRegsForByval - Returns true if the calling convention allows the
+      /// use of registers to pass byval arguments.
+      bool useRegsForByval() const { return CallConv != CallingConv::Fast; }
+
+      const MCPhysReg *shadowRegs() const;
+
+      void allocateRegs(ByValArgInfo &ByVal, unsigned ByValSize, unsigned Align,
+                        CCState &State);
+
       /// 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.
@@ -384,6 +411,7 @@
 
       CallingConv::ID CallConv;
       const MipsSubtarget &Subtarget;
+      SmallVector<ByValArgInfo, 2> ByValArgs;
     };
   protected:
     SDValue lowerLOAD(SDValue Op, SelectionDAG &DAG) const;
@@ -448,9 +476,9 @@
     /// isEligibleForTailCallOptimization - Check whether the call is eligible
     /// for tail call optimization.
     virtual bool
-    isEligibleForTailCallOptimization(const CCState &CCInfo,
+    isEligibleForTailCallOptimization(const MipsCC &MipsCCInfo,
                                       unsigned NextStackOffset,
-                                      const MipsFunctionInfo &FI) const = 0;
+                                      const MipsFunctionInfo& FI) const = 0;
 
     /// copyByValArg - Copy argument registers which were used to pass a byval
     /// argument to the stack. Create a stack frame object for the byval
@@ -459,15 +487,14 @@
                        SelectionDAG &DAG, const ISD::ArgFlagsTy &Flags,
                        SmallVectorImpl<SDValue> &InVals,
                        const Argument *FuncArg, const MipsCC &CC,
-                       unsigned FirstReg, unsigned LastReg,
-                       const CCValAssign &VA) const;
+                       const ByValArgInfo &ByVal, const CCValAssign &VA) const;
 
     /// passByValArg - Pass a byval argument in registers or on stack.
     void passByValArg(SDValue Chain, SDLoc DL,
                       std::deque<std::pair<unsigned, SDValue>> &RegsToPass,
                       SmallVectorImpl<SDValue> &MemOpChains, SDValue StackPtr,
                       MachineFrameInfo *MFI, SelectionDAG &DAG, SDValue Arg,
-                      const MipsCC &CC, unsigned FirstReg, unsigned LastReg,
+                      const MipsCC &CC, const ByValArgInfo &ByVal,
                       const ISD::ArgFlagsTy &Flags, bool isLittle,
                       const CCValAssign &VA) const;