how does SELECT CASE work, INTERNALLY?

[Agamemnus]

Er um I dunno.....

[LooseCaboose]

Code:

$ cat switch.c
int main() {

  int a = 1;

  switch(a) {
  case 1:
    a = 2;
    break;
  case 2:
  case 3:
    a = 4;
    break;
  default:
    a = -1;
    break;
  }
}

$ gcc -S switch.c
$ cat switch.s
       .file   "switch.c"
        .text
        .align 2
.globl main
        .type   main,@function
main:
        pushl   %ebp
        movl    %esp, %ebp
        subl    $8, %esp
        andl    $-16, %esp
        movl    $0, %eax
        subl    %eax, %esp
        movl    $1, -4(%ebp)
        movl    -4(%ebp), %eax
        movl    %eax, -8(%ebp)
        cmpl    $1, -8(%ebp)
        je      .L3
        cmpl    $1, -8(%ebp)
        jl      .L6
        cmpl    $3, -8(%ebp)
        jg      .L6
        jmp     .L5
.L3:
        movl    $2, -4(%ebp)
        jmp     .L2
.L5:
        movl    $4, -4(%ebp)
        jmp     .L2
.L6:
        movl    $-1, -4(%ebp)
.L2:
        leave
        ret
.Lfe1:
        .size   main,.Lfe1-main
        .ident  "GCC: (GNU) 3.2 20020903 (Red Hat Linux 8.0 3.2-7)"