[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/WebAssembly/WebAssemblyRegStackify.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
index 6780f25..c326bdb 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyRegStackify.cpp
@@ -163,7 +163,7 @@
   assert(!MI.isPosition());
   assert(!MI.isTerminator());
 
-  if (MI.isDebugValue())
+  if (MI.isDebugInstr())
     return;
 
   // Check for loads.
@@ -871,7 +871,7 @@
   SmallVector<unsigned, 0> Stack;
   for (MachineBasicBlock &MBB : MF) {
     for (MachineInstr &MI : MBB) {
-      if (MI.isDebugValue())
+      if (MI.isDebugInstr())
         continue;
       for (MachineOperand &MO : reverse(MI.explicit_operands())) {
         if (!MO.isReg())