[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/ARM/Thumb2InstrInfo.cpp b/llvm/lib/Target/ARM/Thumb2InstrInfo.cpp
index 179f113..d5f0ba9 100644
--- a/llvm/lib/Target/ARM/Thumb2InstrInfo.cpp
+++ b/llvm/lib/Target/ARM/Thumb2InstrInfo.cpp
@@ -82,7 +82,7 @@
     MachineBasicBlock::iterator E = MBB->begin();
     unsigned Count = 4; // At most 4 instructions in an IT block.
     while (Count && MBBI != E) {
-      if (MBBI->isDebugValue()) {
+      if (MBBI->isDebugInstr()) {
         --MBBI;
         continue;
       }
@@ -109,7 +109,7 @@
 bool
 Thumb2InstrInfo::isLegalToSplitMBBAt(MachineBasicBlock &MBB,
                                      MachineBasicBlock::iterator MBBI) const {
-  while (MBBI->isDebugValue()) {
+  while (MBBI->isDebugInstr()) {
     ++MBBI;
     if (MBBI == MBB.end())
       return false;