[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/Target/Mips/MipsInstrInfo.cpp b/llvm/lib/Target/Mips/MipsInstrInfo.cpp
index 947d7e4..9254ae6 100644
--- a/llvm/lib/Target/Mips/MipsInstrInfo.cpp
+++ b/llvm/lib/Target/Mips/MipsInstrInfo.cpp
@@ -163,7 +163,7 @@
   // Note that indirect branches are not removed.
   while (I != REnd && removed < 2) {
     // Skip past debug instructions.
-    if (I->isDebugValue()) {
+    if (I->isDebugInstr()) {
       ++I;
       continue;
     }
@@ -195,7 +195,7 @@
   MachineBasicBlock::reverse_iterator I = MBB.rbegin(), REnd = MBB.rend();
 
   // Skip all the debug instructions.
-  while (I != REnd && I->isDebugValue())
+  while (I != REnd && I->isDebugInstr())
     ++I;
 
   if (I == REnd || !isUnpredicatedTerminator(*I)) {
@@ -220,7 +220,7 @@
   // Skip past any debug instruction to see if the second last actual
   // is a branch.
   ++I;
-  while (I != REnd && I->isDebugValue())
+  while (I != REnd && I->isDebugInstr())
     ++I;
 
   if (I != REnd) {