[CodeGen] Add unittest for findDebugLoc, rfindDebugLoc, findPrevDebugLoc and rfindPrevDebugLoc. NFC

- Add some unittests for the findDebugLoc, rfindDebugLoc,
  findPrevDebugLoc and rfindPrevDebugLoc helpers in MachineBasicBlock.

- Clean up code comments and code formatting related to the functions
  mentioned above.

This was extracted as a pre-commit to D150577, adn some of the tests
are commented out since they would crash/assert in a rather
uncontrolled way.

1 files changed, 6 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/MachineBasicBlock.cpp b/llvm/lib/CodeGen/MachineBasicBlock.cpp
index 48b2aa4..1e92318 100644
--- a/llvm/lib/CodeGen/MachineBasicBlock.cpp
+++ b/llvm/lib/CodeGen/MachineBasicBlock.cpp
@@ -1462,7 +1462,7 @@ void MachineBasicBlock::replacePhiUsesWith(MachineBasicBlock *Old,
     }
 }
 
-/// Find the next valid DebugLoc starting at MBBI, skipping any DBG_VALUE
+/// Find the next valid DebugLoc starting at MBBI, skipping any debug
 /// instructions.  Return UnknownLoc if there is none.
 DebugLoc
 MachineBasicBlock::findDebugLoc(instr_iterator MBBI) {
@@ -1481,13 +1481,15 @@ DebugLoc MachineBasicBlock::rfindDebugLoc(reverse_instr_iterator MBBI) {
   return {};
 }
 
-/// Find the previous valid DebugLoc preceding MBBI, skipping and DBG_VALUE
+/// Find the previous valid DebugLoc preceding MBBI, skipping any debug
 /// instructions.  Return UnknownLoc if there is none.
 DebugLoc MachineBasicBlock::findPrevDebugLoc(instr_iterator MBBI) {
-  if (MBBI == instr_begin()) return {};
+  if (MBBI == instr_begin())
+    return {};
   // Skip debug instructions, we don't want a DebugLoc from them.
   MBBI = prev_nodbg(MBBI, instr_begin());
-  if (!MBBI->isDebugInstr()) return MBBI->getDebugLoc();
+  if (!MBBI->isDebugInstr())
+    return MBBI->getDebugLoc();
   return {};
 }