关于GCC 4.8 O2选项一个BUG的讨论-汇编码1

gistfile1.asm

main:
.LFB1016:
        subq    $24, %rsp
.LCFI0:
        xorl    %eax, %eax
        movl    $.LC0, %edi
        leaq    12(%rsp), %rsi
        call    scanf
        movl    12(%rsp), %eax              # n[%eax] <- scanf
        testl   %eax, %eax                  # (n&n) - 0 ?
        js      .L2                         # if negative, goto .L2
        cmpl    $3, %eax                    # $3 - n ?
        je      .L5                         # if equal, goto .L5
.L2:
        movl    $.LC2, %edi
        call    puts                        # printf("-1\n")
        xorl    %eax, %eax
        addq    $24, %rsp
.LCFI1:
        ret                                 # return 0
.L5:
.LCFI2:
        movl    $.LC1, %edi
        xorl    %ecx, %ecx
        movl    $1, %edx
        movl    $2, %esi
        xorl    %eax, %eax
        call    printf                      # printf("2 1 0\n")
        xorl    %edi, %edi
        call    exit                        # exit(0)