[Bug c++/38787] New: generating non-conforming "rep retn"

["zsojka at seznam dot cz" <gcc-bugzilla at gcc dot gnu dot org>]

This report is similiar to http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30976 ,
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29473 and 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29493

Problem is that the bogus "rep ret" is still being generated, but it is
accepted by assembler now.

As shown in http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30976 , the behaviour
of "rep retn" is undefined.

Testcase:
---------------
struct o {
  virtual void a() { }
};

int main(int,char**) {
  new o();
  return 0;
}
----------------

Fails under i386 with this command line:
g++ main.cpp -o main.o -O1 -fomit-frame-pointer

gcc 3.4.6, 4.1.2:
working march: i386 i486 i586 i686
broken march: athlon k8

gcc 4.2.4, 4.3.2, 4.4.0-alpha20081226:
working march: i386 i486 i586
broken march: i686 athlon k8

Fails under x86_64 with this command line:
g++ main.cpp -o main.o -O1
g++ main.cpp -o main.o -O1 -m32 -fomit-frame-pointer

The wrongly compiled function is o::a()


-- 
           Summary: generating non-conforming "rep retn"
           Product: gcc
           Version: 4.3.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: zsojka at seznam dot cz
  GCC host triplet: x86_64-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38787