[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/Hexagon/HexagonAsmPrinter.cpp b/llvm/lib/Target/Hexagon/HexagonAsmPrinter.cpp
index 6b836e2..0ac83ea 100644
--- a/llvm/lib/Target/Hexagon/HexagonAsmPrinter.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonAsmPrinter.cpp
@@ -760,7 +760,7 @@
     MachineBasicBlock::const_instr_iterator MII = MI->getIterator();
 
     for (++MII; MII != MBB->instr_end() && MII->isInsideBundle(); ++MII)
-      if (!MII->isDebugValue() && !MII->isImplicitDef())
+      if (!MII->isDebugInstr() && !MII->isImplicitDef())
         HexagonLowerToMC(MCII, &*MII, MCB, *this);
   } else {
     HexagonLowerToMC(MCII, MI, MCB, *this);