[DebugInfo] Examine all uses of isDebugValue() for debug instructions.

Because we create a new kind of debug instruction, DBG_LABEL, we need to
check all passes which use isDebugValue() to check MachineInstr is debug
instruction or not. When expelling debug instructions, we should expel
both DBG_VALUE and DBG_LABEL. So, I create a new function,
isDebugInstr(), in MachineInstr to check whether the MachineInstr is
debug instruction or not.

This patch has no new test case. I have run regression test and there is
no difference in regression test.

Differential Revision: https://reviews.llvm.org/D45342

Patch by Hsiangkai Wang.

llvm-svn: 331844
diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
index c0e1a7b..9686018 100644
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -467,8 +467,8 @@
         return false;
     }
   }
-  // If DebugLoc does not match then two dbg.values are not identical.
-  if (isDebugValue())
+  // If DebugLoc does not match then two debug instructions are not identical.
+  if (isDebugInstr())
     if (getDebugLoc() && Other.getDebugLoc() &&
         getDebugLoc() != Other.getDebugLoc())
       return false;
@@ -975,7 +975,7 @@
     return false;
   }
 
-  if (isPosition() || isDebugValue() || isTerminator() ||
+  if (isPosition() || isDebugInstr() || isTerminator() ||
       hasUnmodeledSideEffects())
     return false;
 
@@ -1534,6 +1534,7 @@
     if (isIndirectDebugValue())
       OS << " indirect";
   }
+  // TODO: DBG_LABEL
 
   if (AddNewLine)
     OS << '\n';