The -malign-double switch no longer functions correctly with
egcs-c++-1.1.2. C++ code compiled with this switch, then
linked, SEGVs; dying somewhere in the streams library.  This
is demonstrated with a trivial test program:

        #include <cassert>
        #include <fstream>
        #include <iostream>
        #include <string>

        int main()
        {
          using namespace std;
          string name, value;
          ifstream ifs( "input.dat" );
          assert( ifs.good() );
          while( ifs >> value >> name )
            cout << name << "\t" << value << endl;
          return( 0 );
        }

If -O0 is specified, the SEGV generally occurs in the
istream constructor; on the manipulators flush, width or
precision;  or operator<<(). Specifying -Ox, x > 0, usually
causes SEGV from ifstream::~ifstream(). Linking -static may
prevent the SEGV in some instances with optimization, but I
have not tested this extensively. Since the failure is a
SEGV, there is little guarantee that the location of the
signal will provide useful information

The platforms tested were:

  1.  i686 tweaked RH5.2 (to run egcs/pgcc*-1.1.1) upgraded
to RH6.0
  2.  i486 stock RH5.2 upgraded to RH6.0
  3.  i486 clean install of RH6.0
  4.  i586 clean install of RH6.0

The -malign-double option worked with egcs*-1.1.1.

There is no apparent negative effect on plain C code
compiled with the -malign-double switch.

The test program and input data file, a makefile, verbose
assembler with diffs, egcs-c++-1.1.2 -v -a output(make.out),
and this description are available from:

  http://chico.hm.uc.edu/~jmitchel/linux/malign-double/

-jason


------- Additional Comments From   06/04/99 16:39 -------
I failed to specify that -malign-double option worked with egcs*-1.1.1
on RedHat 5.2 with glibc-2.1-0.990222, binutils-2.9.1.0.23-1, and
libstdc++-2.9.0-7.