In my warnings count:

55 /src/hotspot/share/classfile/verifier.cpp
29 /src/hotspot/share/classfile/stackMapFrame.cpp
18 /src/hotspot/share/classfile/stackMapTableFormat.hpp
15 /src/hotspot/share/classfile/stackMapFrame.hpp
10 /src/hotspot/share/classfile/stackMapTable.cpp

The verifiers functions take u2 for bci and index but then use these as int to print out any verification errors or keep in the stack allocated container types for error reporting.   It also has a comment to use int32_t for various counts on purpose, so passing u2 to these counts doesn't make sense.

  // Logically, the _frame_count (as well as many fields in the StackFrame)
  // should be a u2, but if we defined the variable as that type it will
  // be difficult to detect/recover from overflow or underflow conditions.
  // Widening the type and making it signed will help detect these.
  int32_t              _code_length;
  int32_t              _frame_count;     // Stackmap frame count