[Hexagon] Fix compilation error with GCC 6

[rivanvx]

Summary

Compiling Hexagon target with GCC 6 produces "error: should have been
declared inside" due to GCC PR c++/69657 which was merged.

Properly wrapping operator<<() definitions within the namespace llvm
fixes the issue.

Author: domagoj.stolfa

[kparzysz]

Looks good to me.

[rivanvx]

Is there anything else I need to do for this to land?

lib/Target/Hexagon/BitTracker.cpp

raw_ostream &operator<< (raw_ostream &OS, const printv &PV) {
     if (PV.R)
       OS << 'v' << TargetRegisterInfo::virtReg2Index(PV.R);
     else
       OS << 's';
     return OS;
   }
 }
 
-raw_ostream &llvm::operator<<(raw_ostream &OS, const BT::BitValue &BV) {
+namespace llvm {
+  raw_ostream &operator<<(raw_ostream &OS, const BT::BitValue &BV) {
     switch (BV.Type) {
       case BT::BitValue::Top:
         OS << 'T';
         break;
       case BT::BitValue::Zero:
         OS << '0';
         break;
       case BT::BitValue::One:
         OS << '1';
         break;
       case BT::BitValue::Ref:
         OS << printv(BV.RefI.Reg) << '[' << BV.RefI.Pos << ']';
         break;
     }
     return OS;
   }
 
-raw_ostream &llvm::operator<<(raw_ostream &OS, const BT::RegisterCell &RC) {
+  raw_ostream &operator<<(raw_ostream &OS, const BT::RegisterCell &RC) {
     unsigned n = RC.Bits.size();
     OS << "{ w:" << n;
     // Instead of printing each bit value individually, try to group them
     // into logical segments, such as sequences of 0 or 1 bits or references
     // to consecutive bits (e.g. "bits 3-5 are same as bits 7-9 of reg xyz").
     // "Start" will be the index of the beginning of the most recent segment.
     unsigned Start = 0;
     bool SeqRef = false;    // A sequence of refs to consecutive bits.
     bool ConstRef = false;  // A sequence of refs to the same bit.
 
     for (unsigned i = 1, n = RC.Bits.size(); i < n; ++i) {
       const BT::BitValue &V = RC[i];
       const BT::BitValue &SV = RC[Start];
       bool IsRef = (V.Type == BT::BitValue::Ref);
       // If the current value is the same as Start, skip to the next one.
       if (!IsRef && V == SV)
         continue;
       if (IsRef && SV.Type == BT::BitValue::Ref && V.RefI.Reg == SV.RefI.Reg) {
         if (Start+1 == i) {
           SeqRef = (V.RefI.Pos == SV.RefI.Pos+1);
           ConstRef = (V.RefI.Pos == SV.RefI.Pos);
         }
         if (SeqRef && V.RefI.Pos == SV.RefI.Pos+(i-Start))
           continue;
         if (ConstRef && V.RefI.Pos == SV.RefI.Pos)
           continue;
       }
 
       // The current value is different. Print the previous one and reset
       // the Start.
       OS << " [" << Start;
       unsigned Count = i - Start;
       if (Count == 1) {
         OS << "]:" << SV;
       } else {
         OS << '-' << i-1 << "]:";
         if (SV.Type == BT::BitValue::Ref && SeqRef)
           OS << printv(SV.RefI.Reg) << '[' << SV.RefI.Pos << '-'
              << SV.RefI.Pos+(Count-1) << ']';
         else
           OS << SV;
       }
       Start = i;
       SeqRef = ConstRef = false;
     }
 
     OS << " [" << Start;
     unsigned Count = n - Start;
     if (n-Start == 1) {
       OS << "]:" << RC[Start];
     } else {
       OS << '-' << n-1 << "]:";
       const BT::BitValue &SV = RC[Start];
       if (SV.Type == BT::BitValue::Ref && SeqRef)
         OS << printv(SV.RefI.Reg) << '[' << SV.RefI.Pos << '-'
            << SV.RefI.Pos+(Count-1) << ']';
       else
         OS << SV;
     }
     OS << " }";
 
     return OS;
   }
+}
 
 BitTracker::BitTracker(const MachineEvaluator &E, MachineFunction &F)
     : Trace(false), ME(E), MF(F), MRI(F.getRegInfo()), Map(*new CellMapType) {}
 
 BitTracker::~BitTracker() {
   delete &Map;
 }