[Bug target/65459] New: munaligned-access still produce split access codes

["ma.jiang at zte dot com.cn" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65459

            Bug ID: 65459
           Summary: munaligned-access still produce split access codes
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ma.jiang at zte dot com.cn

Hi all,
  The munaligned-access option on ARM can not stop gcc from producing split
access codes. A very simple test 
char mt[20];
void main()
{
    void *mm=&(mt[1]);
  *(( int *)mm)=4;
}
  compiled with -O2 -munaligned-access could reproduce this problem.As we can
see,"*(( int *)mm)=4;"  cause gcc to emit 4 strb instructions not a unaligned
stw .
  In my opinion, this bug is caused by the SLOW_UNALIGNED_ACCESS macro,which is
defined to be 1 in arm.h. It is very strange that  the munaligned-access option
can affect neither  SLOW_UNALIGNED_ACCESS nor STRICT_ALIGNMENT. On PPC,the
mstrict-align can affect STRICT_ALIGNMENTï and SLOW_UNALIGNED_ACCESS is
determined by STRICT_ALIGNMENT, ALIGN, and MODE(args of the
SLOW_UNALIGNED_ACCESS macro). This is a good example for ARM, I think.