[Bug rtl-optimization/17236] inefficient code for long long multiply on x86

[ubizjak at gmail dot com]

------- Comment #11 from ubizjak at gmail dot com  2007-12-18 13:47 -------
Generated code for a similar example is just plain stupid:

--cut here--
int test(long long a, long long b)
{
        return a * b;
}
--cut here--

gcc -O3:

test:
        pushl   %ebp
        movl    %esp, %ebp
        subl    $8, %esp
        movl    %esi, 4(%esp)
        movl    16(%ebp), %esi
        movl    %ebx, (%esp)
        movl    8(%ebp), %ebx
        movl    %esi, %eax
        movl    4(%esp), %esi
        mull    %ebx
        movl    (%esp), %ebx
        movl    %ebp, %esp
        popl    %ebp
        ret

gcc-4.0 is a little less creative and creates:

test:
        pushl   %ebp
        movl    %esp, %ebp
        pushl   %edi
        pushl   %esi
        pushl   %ebx
        movl    8(%ebp), %eax
        mull    16(%ebp)
        popl    %ebx
        popl    %esi
        popl    %edi
        leave
        ret


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17236