Pass DebugLoc and SDLoc by const ref.

This used to be free, copying and moving DebugLocs became expensive
after the metadata rewrite. Passing by reference eliminates a ton of
track/untrack operations. No functionality change intended.

llvm-svn: 272512
diff --git a/llvm/lib/Target/Mips/MipsInstrInfo.h b/llvm/lib/Target/Mips/MipsInstrInfo.h
index b6361a2..4a773ee 100644
--- a/llvm/lib/Target/Mips/MipsInstrInfo.h
+++ b/llvm/lib/Target/Mips/MipsInstrInfo.h
@@ -59,7 +59,7 @@
 
   unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
                         MachineBasicBlock *FBB, ArrayRef<MachineOperand> Cond,
-                        DebugLoc DL) const override;
+                        const DebugLoc &DL) const override;
 
   bool
   ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const override;
@@ -146,8 +146,8 @@
                      MachineBasicBlock *&BB,
                      SmallVectorImpl<MachineOperand> &Cond) const;
 
-  void BuildCondBr(MachineBasicBlock &MBB, MachineBasicBlock *TBB, DebugLoc DL,
-                   ArrayRef<MachineOperand> Cond) const;
+  void BuildCondBr(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
+                   const DebugLoc &DL, ArrayRef<MachineOperand> Cond) const;
 };
 
 /// Create MipsInstrInfo objects.