sum.s sum_tail.s
 1 _Z3sumRKSt6vectorIiSaIiEE:                                                                                                                                            
 2 .LFB456:                                                                                                                                                              
 3     .cfi_startproc
 4     movq    (%rdi), %rdx
 5     movq    8(%rdi), %rcx
 6     xorl    %eax, %eax
 7     cmpq    %rcx, %rdx
 8     je  .L4                                                                                                                                                           
 9     .p2align 4,,10
10     .p2align 3
11 .L3:                                                                                                                                                                  
12     addl    (%rdx), %eax
13     addq    $4, %rdx
14     cmpq    %rdx, %rcx
15     jne .L3                                                                                                                                                           
16     rep ret
17 .L4:                                                                                                                                                                  
18     .p2align 4,,2
19     rep ret
20     .cfi_endproc
 1 _Z8sum_tailRKSt6vectorIiSaIiEE:                                                                                                                                       
 2 .LFB458:                                                                                                                                                              
 3     .cfi_startproc
 4     movq    (%rdi), %rdx
 5     movq    8(%rdi), %rcx
 6     xorl    %eax, %eax
 7     cmpq    %rcx, %rdx
 8     je  .L12                                                                                                                                                          
 9     .p2align 4,,10
10     .p2align 3
11 .L11:                                                                                                                                                                 
12     addl    (%rdx), %eax
13     addq    $4, %rdx
14     cmpq    %rdx, %rcx
15     jne .L11                                                                                                                                                          
16     rep ret
17 .L12:                                                                                                                                                                 
18     .p2align 4,,2
19     rep ret
20     .cfi_endproc