[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/AMDGPU/GCNIterativeScheduler.cpp b/llvm/lib/Target/AMDGPU/GCNIterativeScheduler.cpp
index 9fecd85..bf84139 100644
--- a/llvm/lib/Target/AMDGPU/GCNIterativeScheduler.cpp
+++ b/llvm/lib/Target/AMDGPU/GCNIterativeScheduler.cpp
@@ -69,14 +69,14 @@
   auto I = Begin;
   MaxInstNum = std::max(MaxInstNum, 1u);
   for (; I != End && MaxInstNum; ++I, --MaxInstNum) {
-    if (!I->isDebugValue() && LIS)
+    if (!I->isDebugInstr() && LIS)
       OS << LIS->getInstructionIndex(*I);
     OS << '\t' << *I;
   }
   if (I != End) {
     OS << "\t...\n";
     I = std::prev(End);
-    if (!I->isDebugValue() && LIS)
+    if (!I->isDebugInstr() && LIS)
       OS << LIS->getInstructionIndex(*I);
     OS << '\t' << *I;
   }
@@ -384,10 +384,10 @@
     if (MI != &*Top) {
       BB->remove(MI);
       BB->insert(Top, MI);
-      if (!MI->isDebugValue())
+      if (!MI->isDebugInstr())
         LIS->handleMove(*MI, true);
     }
-    if (!MI->isDebugValue()) {
+    if (!MI->isDebugInstr()) {
       // Reset read - undef flags and update them later.
       for (auto &Op : MI->operands())
         if (Op.isReg() && Op.isDef())