[Bug c/28405] New: 4.x code generation regression relative to 3.4.6

["vda dot linux at googlemail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

gcc 3.4.x generates a bit suboptimal code on the below fragment.
gcc 4.x generates code which is a bit more suboptimal.

unsigned v;
void g(unsigned A)
/* gcc -O2 -fomit-frame-pointer -S:
gcc-3.4.3, 3.4.6:
        movl    $-858993459, %eax
        mull    4(%esp)
        movl    %edx, %eax      // huh?
        shrl    $3, %eax
        movl    %eax, v
        ret
gcc-4.0.0,4.1.1:
        movl    $-858993459, %eax
        mull    4(%esp)
        movl    %edx, %eax      // huh?
        xorl    %edx, %edx      // huh??
        shrl    $3, %eax
        movl    %eax, v
        ret
*/
{
        v = (A * 3435973837ULL) >> 35;
}


-- 
           Summary: 4.x code generation regression relative to 3.4.6
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: vda dot linux at googlemail dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28405