int op_index(char c) {
  switch (c) {
  case '+':
    return 0;
  case '-':
    return 1;
  case '*':
    return 2;
  case '/':
    return 3;
  case '%':
    return 4;
  case '=':
    return 5;
  case '!':
    return 6;
  case '>':
    return 7;
  case '<':
    return 8;
  case ']':
    return 9;
  case '[':
    return 10;
  case '}':
    return 11;
  case '{':
    return 12;
  case '&':
    return 13;
  case '^':
    return 14;
  case '|':
    return 15;
  default:
    return -1;
  }
}


x86 assembly (clang, -O0):
<op_index>:
push   %rbp
mov    %rsp,%rbp
mov    %dil,%al
mov    %al,-0x5(%rbp)
movsbl -0x5(%rbp),%eax
add    $0xffffffdf,%eax
mov    %eax,%ecx
mov    %rcx,-0x10(%rbp)
sub    $0x5c,%eax
ja     11f4 <op_index+0xf4>
mov    -0x10(%rbp),%rax
lea    0xed5(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
movl   $0x0,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0x1,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0x2,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0x3,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0x4,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0x5,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0x6,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0x7,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0x8,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0x9,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0xa,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0xb,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0xc,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0xd,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0xe,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0xf,-0x4(%rbp)
jmp    11fb <op_index+0xfb>
movl   $0xffffffff,-0x4(%rbp)
mov    -0x4(%rbp),%eax
pop    %rbp
ret

x86 assembly (clang, -O2):
<op_index>:
add    $0xffffffdf,%edi
cmp    $0x5c,%edi
ja     1174 <op_index+0x74>
xor    %eax,%eax
lea    0xeef(%rip),%rcx
movslq (%rcx,%rdi,4),%rdx
add    %rcx,%rdx
jmp    *%rdx
mov    $0x6,%eax
ret
mov    $0x4,%eax
ret
mov    $0xd,%eax
ret
mov    $0x2,%eax
ret
mov    $0x1,%eax
ret
mov    $0x3,%eax
ret
mov    $0x8,%eax
ret
mov    $0x5,%eax
ret
mov    $0x7,%eax
ret
mov    $0xa,%eax
ret
mov    $0x9,%eax
ret
mov    $0xe,%eax
ret
mov    $0xc,%eax
ret
mov    $0xf,%eax
ret
mov    $0xb,%eax
ret
mov    $0xffffffff,%eax
ret

LLVM IR (-O0):
define i32 @op_index(i8 signext %0) {
%2 = alloca i32
%3 = alloca i8
store i8 %0, i8* %3
%4 = load i8, i8* %3
%5 = sext i8 %4 to i32
switch i32 %5, label %22 [
i32 43, label %6
i32 45, label %7
i32 42, label %8
i32 47, label %9
i32 37, label %10
i32 61, label %11
i32 33, label %12
i32 62, label %13
i32 60, label %14
i32 93, label %15
i32 91, label %16
i32 125, label %17
i32 123, label %18
i32 38, label %19
i32 94, label %20
i32 124, label %21
]
6: ; preds = %1
store i32 0, i32* %2
br label %23
7: ; preds = %1
store i32 1, i32* %2
br label %23
8: ; preds = %1
store i32 2, i32* %2
br label %23
9: ; preds = %1
store i32 3, i32* %2
br label %23
10: ; preds = %1
store i32 4, i32* %2
br label %23
11: ; preds = %1
store i32 5, i32* %2
br label %23
12: ; preds = %1
store i32 6, i32* %2
br label %23
13: ; preds = %1
store i32 7, i32* %2
br label %23
14: ; preds = %1
store i32 8, i32* %2
br label %23
15: ; preds = %1
store i32 9, i32* %2
br label %23
16: ; preds = %1
store i32 10, i32* %2
br label %23
17: ; preds = %1
store i32 11, i32* %2
br label %23
18: ; preds = %1
store i32 12, i32* %2
br label %23
19: ; preds = %1
store i32 13, i32* %2
br label %23
20: ; preds = %1
store i32 14, i32* %2
br label %23
21: ; preds = %1
store i32 15, i32* %2
br label %23
22: ; preds = %1
store i32 -1, i32* %2
br label %23
23: ; preds = %22, %21, %20, %19, %18, %17, %16, %15, %14, %13, %12, %11, %10, %9, %8, %7, %6
%24 = load i32, i32* %2
ret i32 %24
}

LLVM IR (-O2):
define i32 @op_index(i8 signext %0) {
%2 = sext i8 %0 to i32
switch i32 %2, label %18 [
i32 43, label %19
i32 45, label %3
i32 42, label %4
i32 47, label %5
i32 37, label %6
i32 61, label %7
i32 33, label %8
i32 62, label %9
i32 60, label %10
i32 93, label %11
i32 91, label %12
i32 125, label %13
i32 123, label %14
i32 38, label %15
i32 94, label %16
i32 124, label %17
]
3: ; preds = %1
br label %19
4: ; preds = %1
br label %19
5: ; preds = %1
br label %19
6: ; preds = %1
br label %19
7: ; preds = %1
br label %19
8: ; preds = %1
br label %19
9: ; preds = %1
br label %19
10: ; preds = %1
br label %19
11: ; preds = %1
br label %19
12: ; preds = %1
br label %19
13: ; preds = %1
br label %19
14: ; preds = %1
br label %19
15: ; preds = %1
br label %19
16: ; preds = %1
br label %19
17: ; preds = %1
br label %19
18: ; preds = %1
br label %19
19: ; preds = %1, %18, %17, %16, %15, %14, %13, %12, %11, %10, %9, %8, %7, %6, %5, %4, %3
%20 = phi i32 [ -1, %18 ], [ 15, %17 ], [ 14, %16 ], [ 13, %15 ], [ 12, %14 ], [ 11, %13 ], [ 10, %12 ], [ 9, %11 ], [ 8, %10 ], [ 7, %9 ], [ 6, %8 ], [ 5, %7 ], [ 4, %6 ], [ 3, %5 ], [ 2, %4 ], [ 1, %3 ], [ 0, %1 ]
ret i32 %20
}