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/AArch64/AArch64FrameLowering.cpp b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
index d7afd88..48d4e11 100644
--- a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -317,8 +317,8 @@
 // decrement/increment to allocate/deallocate the callee-save stack area by
 // converting store/load to use pre/post increment version.
 static MachineBasicBlock::iterator convertCalleeSaveRestoreToSPPrePostIncDec(
-    MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI, DebugLoc DL,
-    const TargetInstrInfo *TII, int CSStackSizeInc) {
+    MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
+    const DebugLoc &DL, const TargetInstrInfo *TII, int CSStackSizeInc) {
 
   unsigned NewOpc;
   bool NewIsUnscaled = false;