Since 5.0.2 release gcc-9.0.1 fails to compile kernel with -march= option
with the following output:

<...>
  CC      arch/x86/entry/vdso/vma.o
In file included from ./arch/x86/include/asm/atomic.h:265,
                 from ./arch/x86/include/asm/msr.h:67,
                 from ./arch/x86/include/asm/processor.h:21,
                 from ./arch/x86/include/asm/cpufeature.h:5,
                 from ./arch/x86/include/asm/thread_info.h:53,
                 from ./include/linux/thread_info.h:38,
                 from ./arch/x86/include/asm/preempt.h:7,
                 from ./include/linux/preempt.h:78,
                 from ./include/linux/spinlock.h:51,
                 from ./include/linux/mmzone.h:8,
                 from ./include/linux/gfp.h:6,
                 from ./include/linux/mm.h:10,
                 from arch/x86/entry/vdso/vma.c:7:
./arch/x86/include/asm/mshyperv.h: In function ‘vmbus_signal_eom’:
./arch/x86/include/asm/mshyperv.h:61:14: warning: taking address of packed member of ‘struct hv_message_header’ may result in an unaligned pointer value [-Waddress-of-packed-member]
   61 |  if (cmpxchg(&msg->header.message_type, old_msg_type,
./include/asm-generic/atomic-instrumented.h:420:26: note: in definition of macro ‘cmpxchg’
  420 |  typeof(ptr) __ai_ptr = (ptr);     \
      |                          ^~~
  CC      arch/x86/entry/vdso/vdso32-setup.o
  LDS     arch/x86/entry/vdso/vdso.lds
  AS      arch/x86/entry/vdso/vdso-note.o
  CC      arch/x86/entry/vdso/vclock_gettime.o
In file included from ./arch/x86/include/asm/atomic.h:265,
                 from ./arch/x86/include/asm/msr.h:67,
                 from ./arch/x86/include/asm/processor.h:21,
                 from ./arch/x86/include/asm/cpufeature.h:5,
                 from ./arch/x86/include/asm/thread_info.h:53,
                 from ./include/linux/thread_info.h:38,
                 from ./arch/x86/include/asm/preempt.h:7,
                 from ./include/linux/preempt.h:78,
                 from ./include/linux/spinlock.h:51,
                 from ./include/linux/seqlock.h:36,
                 from ./include/linux/time.h:6,
                 from ./include/uapi/linux/timex.h:56,
                 from ./include/linux/timex.h:56,
                 from ./include/linux/clocksource.h:13,
                 from ./arch/x86/include/asm/vgtod.h:6,
                 from arch/x86/entry/vdso/vclock_gettime.c:15:
./arch/x86/include/asm/mshyperv.h: In function ‘vmbus_signal_eom’:
./arch/x86/include/asm/mshyperv.h:61:14: warning: taking address of packed member of ‘struct hv_message_header’ may result in an unaligned pointer value [-Waddress-of-packed-member]
   61 |  if (cmpxchg(&msg->header.message_type, old_msg_type,
./include/asm-generic/atomic-instrumented.h:420:26: note: in definition of macro ‘cmpxchg’
  420 |  typeof(ptr) __ai_ptr = (ptr);     \
      |                          ^~~
  CC      arch/x86/entry/vdso/vgetcpu.o
  VDSO    arch/x86/entry/vdso/vdso64.so.dbg
  OBJCOPY arch/x86/entry/vdso/vdso64.so
  HOSTCC  arch/x86/entry/vdso/vdso2c
  VDSO2C  arch/x86/entry/vdso/vdso-image-64.c
  CC      arch/x86/entry/vdso/vdso-image-64.o
  LDS     arch/x86/entry/vdso/vdso32/vdso32.lds
  CC      arch/x86/entry/vdso/vdso32/vclock_gettime.o
In file included from ./arch/x86/include/asm/atomic.h:265,
                 from ./arch/x86/include/asm/msr.h:67,
                 from ./arch/x86/include/asm/processor.h:21,
                 from ./arch/x86/include/asm/cpufeature.h:5,
                 from ./arch/x86/include/asm/thread_info.h:53,
                 from ./include/linux/thread_info.h:38,
                 from ./arch/x86/include/asm/preempt.h:7,
                 from ./include/linux/preempt.h:78,
                 from ./include/linux/spinlock.h:51,
                 from ./include/linux/seqlock.h:36,
                 from ./include/linux/time.h:6,
                 from ./include/uapi/linux/timex.h:56,
                 from ./include/linux/timex.h:56,
                 from ./include/linux/clocksource.h:13,
                 from ./arch/x86/include/asm/vgtod.h:6,
                 from arch/x86/entry/vdso/vdso32/../vclock_gettime.c:15,
                 from arch/x86/entry/vdso/vdso32/vclock_gettime.c:31:
./arch/x86/include/asm/mshyperv.h: In function ‘vmbus_signal_eom’:
./arch/x86/include/asm/mshyperv.h:61:14: warning: taking address of packed member of ‘struct hv_message_header’ may result in an unaligned pointer value [-Waddress-of-packed-member]
   61 |  if (cmpxchg(&msg->header.message_type, old_msg_type,
./include/asm-generic/atomic-instrumented.h:420:26: note: in definition of macro ‘cmpxchg’
  420 |  typeof(ptr) __ai_ptr = (ptr);     \
      |                          ^~~
  AS      arch/x86/entry/vdso/vdso32/note.o
  AS      arch/x86/entry/vdso/vdso32/system_call.o
  AS      arch/x86/entry/vdso/vdso32/sigreturn.o
  VDSO    arch/x86/entry/vdso/vdso32.so.dbg
  OBJCOPY arch/x86/entry/vdso/vdso32.so
  VDSO2C  arch/x86/entry/vdso/vdso-image-32.c
  CC      arch/x86/entry/vdso/vdso-image-32.o
  AR      arch/x86/entry/vdso/built-in.a
  CC      arch/x86/entry/vsyscall/vsyscall_gtod.o
  CC      arch/x86/entry/vsyscall/vsyscall_64.o
  AS      arch/x86/entry/vsyscall/vsyscall_emu_64.o
  AR      arch/x86/entry/vsyscall/built-in.a
  AS      arch/x86/entry/entry_64.o
  AS      arch/x86/entry/thunk_64.o
  CC      arch/x86/entry/syscall_64.o
  CC      arch/x86/entry/common.o
  AS      arch/x86/entry/entry_64_compat.o
  CC      arch/x86/entry/syscall_32.o
  AR      arch/x86/entry/built-in.a
  CC      arch/x86/events/amd/core.o
In file included from arch/x86/events/amd/core.c:8:
arch/x86/events/amd/../perf_event.h:1035:45: warning: ‘struct cpu_hw_event’ declared inside parameter list will not be visible outside of this definition or declaration
 1035 | static inline int intel_cpuc_prepare(struct cpu_hw_event *cpuc, int cpu)
      |                                             ^~~~~~~~~~~~
arch/x86/events/amd/../perf_event.h:1040:45: warning: ‘struct cpu_hw_event’ declared inside parameter list will not be visible outside of this definition or declaration
 1040 | static inline void intel_cpuc_finish(struct cpu_hw_event *cpuc)
      |                                             ^~~~~~~~~~~~
  CC      arch/x86/events/amd/uncore.o
  CC      arch/x86/events/amd/ibs.o
In file included from arch/x86/events/amd/ibs.c:19:
arch/x86/events/amd/../perf_event.h:1035:45: warning: ‘struct cpu_hw_event’ declared inside parameter list will not be visible outside of this definition or declaration
 1035 | static inline int intel_cpuc_prepare(struct cpu_hw_event *cpuc, int cpu)
      |                                             ^~~~~~~~~~~~
arch/x86/events/amd/../perf_event.h:1040:45: warning: ‘struct cpu_hw_event’ declared inside parameter list will not be visible outside of this definition or declaration
 1040 | static inline void intel_cpuc_finish(struct cpu_hw_event *cpuc)
      |                                             ^~~~~~~~~~~~
  CC      arch/x86/events/amd/iommu.o
In file included from arch/x86/events/amd/iommu.c:21:
arch/x86/events/amd/../perf_event.h:1035:45: warning: ‘struct cpu_hw_event’ declared inside parameter list will not be visible outside of this definition or declaration
 1035 | static inline int intel_cpuc_prepare(struct cpu_hw_event *cpuc, int cpu)
      |                                             ^~~~~~~~~~~~
arch/x86/events/amd/../perf_event.h:1040:45: warning: ‘struct cpu_hw_event’ declared inside parameter list will not be visible outside of this definition or declaration
 1040 | static inline void intel_cpuc_finish(struct cpu_hw_event *cpuc)
      |                                             ^~~~~~~~~~~~
  AR      arch/x86/events/amd/built-in.a
  CC [M]  arch/x86/events/amd/power.o
In file included from arch/x86/events/amd/power.c:17:
arch/x86/events/amd/../perf_event.h:1035:45: warning: ‘struct cpu_hw_event’ declared inside parameter list will not be visible outside of this definition or declaration
 1035 | static inline int intel_cpuc_prepare(struct cpu_hw_event *cpuc, int cpu)
      |                                             ^~~~~~~~~~~~
arch/x86/events/amd/../perf_event.h:1040:45: warning: ‘struct cpu_hw_event’ declared inside parameter list will not be visible outside of this definition or declaration
 1040 | static inline void intel_cpuc_finish(struct cpu_hw_event *cpuc)
      |                                             ^~~~~~~~~~~~
  CC      arch/x86/events/core.o
In file included from arch/x86/events/core.c:44:
arch/x86/events/perf_event.h:1035:45: warning: ‘struct cpu_hw_event’ declared inside parameter list will not be visible outside of this definition or declaration
 1035 | static inline int intel_cpuc_prepare(struct cpu_hw_event *cpuc, int cpu)
      |                                             ^~~~~~~~~~~~
arch/x86/events/perf_event.h:1040:45: warning: ‘struct cpu_hw_event’ declared inside parameter list will not be visible outside of this definition or declaration
 1040 | static inline void intel_cpuc_finish(struct cpu_hw_event *cpuc)
      |                                             ^~~~~~~~~~~~
arch/x86/events/core.c: In function ‘free_fake_cpuc’:
arch/x86/events/core.c:1998:20: error: passing argument 1 of ‘intel_cpuc_finish’ from incompatible pointer type [-Werror=incompatible-pointer-types]
 1998 |  intel_cpuc_finish(cpuc);
      |                    ^~~~
      |                    |
      |                    struct cpu_hw_events *
In file included from arch/x86/events/core.c:44:
arch/x86/events/perf_event.h:1040:59: note: expected ‘struct cpu_hw_event *’ but argument is of type ‘struct cpu_hw_events *’
 1040 | static inline void intel_cpuc_finish(struct cpu_hw_event *cpuc)
      |                                      ~~~~~~~~~~~~~~~~~~~~~^~~~
arch/x86/events/core.c: In function ‘allocate_fake_cpuc’:
arch/x86/events/core.c:2012:25: error: passing argument 1 of ‘intel_cpuc_prepare’ from incompatible pointer type [-Werror=incompatible-pointer-types]
 2012 |  if (intel_cpuc_prepare(cpuc, cpu))
      |                         ^~~~
      |                         |
      |                         struct cpu_hw_events *
In file included from arch/x86/events/core.c:44:
arch/x86/events/perf_event.h:1035:59: note: expected ‘struct cpu_hw_event *’ but argument is of type ‘struct cpu_hw_events *’
 1035 | static inline int intel_cpuc_prepare(struct cpu_hw_event *cpuc, int cpu)
      |                                      ~~~~~~~~~~~~~~~~~~~~~^~~~
cc1: some warnings being treated as errors
make[2]: *** [scripts/Makefile.build:277: arch/x86/events/core.o] Error 1
make[1]: *** [scripts/Makefile.build:492: arch/x86/events] Error 2
make: *** [Makefile:1043: arch/x86] Error 2