There were some warnings from methodData.hpp and methodData.cpp:

3048 src/hotspot/share/oops/methodData.hpp
9 src/hotspot/share/oops/methodData.cpp

eg:

/src/hotspot/share/oops/methodData.hpp:207:28: warning: conversion from 'int' to 'u1' {aka 'unsigned char'} may change value [-Wconversion]
  207 |     _header._struct._flags |= (0x1 << flag_number);
      |     ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
/src/hotspot/share/oops/methodData.hpp: In static member function 'static u8 DataLayout::flag_mask_to_header_mask(uint)':
/src/hotspot/share/oops/methodData.hpp:238:35: warning: conversion from 'uint' {aka 'unsigned int'} to 'u1' {aka 'unsigned char'} may change value [-Wconversion]
  238 |     temp._header._struct._flags = byte_constant;
      |                                   ^~~~~~~~~~~~~
/src/hotspot/share/oops/methodData.hpp: In member function 'void ProfileData::set_flag_at(int)':
/src/hotspot/share/oops/methodData.hpp:348:25: warning: conversion from 'int' to 'u1' {aka 'unsigned char'} may change value [-Wconversion]
  348 |     data()->set_flag_at(flag_number);
      |                         ^~~~~~~~~~~
/src/hotspot/share/oops/methodData.hpp: In member function 'bool ProfileData::flag_at(int) const':
/src/hotspot/share/oops/methodData.hpp:351:28: warning: conversion from 'int' to 'u1' {aka 'unsigned char'} may change value [-Wconversion]
  351 |     return data()->flag_at(flag_number);
      |                            ^~~~~~~~~~~
/src/hotspot/share/oops/methodData.hpp: In static member function 'static int ProfileData::flag_number_to_constant(int)': 
/src/hotspot/share/oops/methodData.hpp:359:48: warning: conversion from 'int' to 'u1' {aka 'unsigned char'} may change value [-Wconversion]
  359 |     return DataLayout::flag_number_to_constant(flag_number);
      |