[Bug regression/19935] New: unexpected "bx lr" in arm mode.

["pluto at pld-linux dot org" <gcc-bugzilla at gcc dot gnu dot org>]

I have a simple testcase:   
   
void test()   
{   
}   
   
# arm-linux-gcc test.c -S -O2 produces:   
   
test:   
        @ args = 0, pretend = 0, frame = 0   
        @ frame_needed = 0, uses_anonymous_args = 0   
        @ link register save eliminated.   
        @ lr needed for prologue   
        mov     pc, lr   
   
   
# arm-linux-gcc test.c -S -O2 -mcpu=arm7tdmi-s produces:   
   
test:   
        @ args = 0, pretend = 0, frame = 0   
        @ frame_needed = 0, uses_anonymous_args = 0   
        @ link register save eliminated.   
        @ lr needed for prologue   
        bx      lr   
   
-mthumb-interwork is disabled by default (vide man).   
why gcc4 produces "bx lr" ? (gcc34 works fine).  
  
# arm-linux-gcc -v 
Reading specs from /usr/lib/gcc/arm-linux/4.0.0/specs 
Configured with: ../configure --prefix=/usr 
--with-sysroot=/home/users/pluto/rpm/BUILD/gcc-4.0-20050130/fake-root 
--infodir=/usr/share/info --mandir=/usr/share/man --bindir=/usr/bin 
--libdir=/usr/lib --libexecdir=/usr/lib --disable-shared --disable-threads 
--enable-languages=c,c++ --enable-c99 --enable-long-long --with-gnu-as 
--with-gnu-ld --with-system-zlib --with-multilib 
--with-sysroot=/home/users/pluto/rpm/BUILD/gcc-4.0-20050130/fake-root 
--without-x --target=arm-linux --host=i686-pld-linux --build=i686-pld-linux 
Thread model: single 
gcc version 4.0.0 20050130 (experimental)

-- 
           Summary: unexpected "bx lr" in arm mode.
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: regression
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pluto at pld-linux dot org
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-linux
  GCC host triplet: i686-linux
GCC target triplet: arm-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19935