[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/AArch64/AArch64FrameLowering.cpp b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
index d233827..2523cfd 100644
--- a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -162,7 +162,7 @@
   // realistically that's not a big deal at this stage of the game.
   for (MachineBasicBlock &MBB : MF) {
     for (MachineInstr &MI : MBB) {
-      if (MI.isDebugValue() || MI.isPseudo() ||
+      if (MI.isDebugInstr() || MI.isPseudo() ||
           MI.getOpcode() == AArch64::ADDXri ||
           MI.getOpcode() == AArch64::ADDSXri)
         continue;