Debug Info: clean up usage of Verify.

No functionality change.
It should suffice to check the type of a debug info metadata, instead of
calling Verify. For cases where we know the type of a DI metadata, use
assert.

Also update testing cases to make them conform to the format of DI classes.

llvm-svn: 185135
diff --git a/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp b/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
index ef66bf8..06a0f26 100644
--- a/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
+++ b/llvm/lib/Transforms/Instrumentation/GCOVProfiling.cpp
@@ -434,7 +434,10 @@
     DIArray SPs = CU.getSubprograms();
     for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) {
       DISubprogram SP(SPs.getElement(i));
-      if (!SP.Verify()) continue;
+      assert((!SP || SP.isSubprogram()) &&
+        "A MDNode in subprograms of a CU should be null or a DISubprogram.");
+      if (!SP)
+        continue;
 
       Function *F = SP.getFunction();
       if (!F) continue;
@@ -483,7 +486,10 @@
     SmallVector<std::pair<GlobalVariable *, MDNode *>, 8> CountersBySP;
     for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i) {
       DISubprogram SP(SPs.getElement(i));
-      if (!SP.Verify()) continue;
+      assert((!SP || SP.isSubprogram()) &&
+        "A MDNode in subprograms of a CU should be null or a DISubprogram.");
+      if (!SP)
+        continue;
       Function *F = SP.getFunction();
       if (!F) continue;
       if (!Result) Result = true;