[Bug c/50136] New: Loop inc/dec optimization.

["bratsinot at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50136

             Bug #: 50136
           Summary: Loop inc/dec optimization.
    Classification: Unclassified
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: bratsinot@gmail.com


Maybe shoud use inc and dec, than sub $1, %ebx?

GCC translate this C code:
 unsigned int i;
 scanf("%u", &i);
 for(unsigned int qwe=i; qwe>0; qwe--)
 printf("fg");

Into this Assembler code:
    leaq    12(%rsp), %rsi
    xorl    %eax, %eax
    movl    $.LC0, %edi
    call    __isoc99_scanf
    movl    12(%rsp), %ebx
    testl    %ebx, %ebx
    je    .L2
    .p2align 4,,10
    .p2align 3
.L4:
    xorl    %eax, %eax
    movl    $.LC1, %edi
    call    printf
    subl    $1, %ebx   ;This not good, dec %ebx is better
    jne    .L4