When building for Arm32 with GCC 11 (as shipped with latest Ubuntu versions) there are plenty compiler warnings like:

Creating support/modules_libs/java.base/server/libjvm.so from 926 file(s)
In file included from /workspace/src/hotspot/share/runtime/frame.inline.hpp:45,
                 from /workspace/src/hotspot/cpu/arm/abstractInterpreter_arm.cpp:34:
/workspace/src/hotspot/cpu/arm/frame_arm.inline.hpp: In member function 'oopDesc* frame::saved_oop_result(RegisterMap*) const':
/workspace/src/hotspot/cpu/arm/frame_arm.inline.hpp:200:54: warning: 'this' pointer is null [-Wnonnull]
  200 | oop* result_adr = (oop*) map->location(R0->as_VMReg(), nullptr);
 
These warnings have already been ignored for other platforms in JDK-8270083 and JDK-8271869.