#define NULL ((void *)0)
typedef unsigned long size_t; // Customize by platform.
typedef long intptr_t;
typedef unsigned long uintptr_t;
typedef long scalar_t__; // Either arithmetic or pointer type.
/* By default, we understand bool (as a convenience). */
typedef int bool;
#define false 0
#define true 1

/* Forward declarations */

/* Type definitions */

/* Variables and functions */
int toupper(char);
int letter_num(char c) {
  switch (toupper(c)) {
  case 'A':
    return 0;
  case 'B':
    return 1;
  case 'C':
    return 2;
  case 'D':
    return 3;
  case 'E':
    return 4;
  case 'F':
    return 5;
  case 'G':
    return 6;
  case 'H':
    return 7;
  case 'I':
    return 8;
  case 'J':
    return 9;
  case 'K':
    return 10;
  case 'L':
    return 11;
  case 'M':
    return 12;
  case 'N':
    return 13;
  case 'O':
    return 14;
  case 'P':
    return 15;
  case 'Q':
    return 16;
  case 'R':
    return 17;
  case 'S':
    return 18;
  case 'T':
    return 19;
  case 'U':
    return 20;
  case 'V':
    return 21;
  case 'W':
    return 22;
  case 'X':
    return 23;
  case 'Y':
    return 24;
  case 'Z':
    return 25;
  }
  return -1;
}


x86 assembly (clang, -O0):
<letter_num>:
push   %rbp
mov    %rsp,%rbp
sub    $0x10,%rsp
mov    %dil,%al
mov    %al,-0x5(%rbp)
movsbl -0x5(%rbp),%edi
call   1030 <toupper@plt>
add    $0xffffffbf,%eax
mov    %eax,%ecx
mov    %rcx,-0x10(%rbp)
sub    $0x19,%eax
ja     1285 <letter_num+0x175>
mov    -0x10(%rbp),%rax
lea    0xebc(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
movl   $0x0,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x1,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x2,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x3,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x4,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x5,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x6,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x7,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x8,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x9,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0xa,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0xb,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0xc,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0xd,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0xe,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0xf,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x10,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x11,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x12,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x13,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x14,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x15,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x16,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x17,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x18,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0x19,-0x4(%rbp)
jmp    128c <letter_num+0x17c>
movl   $0xffffffff,-0x4(%rbp)
mov    -0x4(%rbp),%eax
add    $0x10,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<letter_num>:
push   %rax
call   1030 <toupper@plt>
add    $0xffffffbf,%eax
cmp    $0x1a,%eax
mov    $0xffffffff,%ecx
cmovae %ecx,%eax
pop    %rcx
ret

LLVM IR (-O0):
define i32 @letter_num(i8 signext %0) {
%2 = alloca i32
%3 = alloca i8
store i8 %0, i8* %3
%4 = load i8, i8* %3
%5 = call i32 @toupper(i8 signext %4)
switch i32 %5, label %32 [
i32 65, label %6
i32 66, label %7
i32 67, label %8
i32 68, label %9
i32 69, label %10
i32 70, label %11
i32 71, label %12
i32 72, label %13
i32 73, label %14
i32 74, label %15
i32 75, label %16
i32 76, label %17
i32 77, label %18
i32 78, label %19
i32 79, label %20
i32 80, label %21
i32 81, label %22
i32 82, label %23
i32 83, label %24
i32 84, label %25
i32 85, label %26
i32 86, label %27
i32 87, label %28
i32 88, label %29
i32 89, label %30
i32 90, label %31
]
6: ; preds = %1
store i32 0, i32* %2
br label %33
7: ; preds = %1
store i32 1, i32* %2
br label %33
8: ; preds = %1
store i32 2, i32* %2
br label %33
9: ; preds = %1
store i32 3, i32* %2
br label %33
10: ; preds = %1
store i32 4, i32* %2
br label %33
11: ; preds = %1
store i32 5, i32* %2
br label %33
12: ; preds = %1
store i32 6, i32* %2
br label %33
13: ; preds = %1
store i32 7, i32* %2
br label %33
14: ; preds = %1
store i32 8, i32* %2
br label %33
15: ; preds = %1
store i32 9, i32* %2
br label %33
16: ; preds = %1
store i32 10, i32* %2
br label %33
17: ; preds = %1
store i32 11, i32* %2
br label %33
18: ; preds = %1
store i32 12, i32* %2
br label %33
19: ; preds = %1
store i32 13, i32* %2
br label %33
20: ; preds = %1
store i32 14, i32* %2
br label %33
21: ; preds = %1
store i32 15, i32* %2
br label %33
22: ; preds = %1
store i32 16, i32* %2
br label %33
23: ; preds = %1
store i32 17, i32* %2
br label %33
24: ; preds = %1
store i32 18, i32* %2
br label %33
25: ; preds = %1
store i32 19, i32* %2
br label %33
26: ; preds = %1
store i32 20, i32* %2
br label %33
27: ; preds = %1
store i32 21, i32* %2
br label %33
28: ; preds = %1
store i32 22, i32* %2
br label %33
29: ; preds = %1
store i32 23, i32* %2
br label %33
30: ; preds = %1
store i32 24, i32* %2
br label %33
31: ; preds = %1
store i32 25, i32* %2
br label %33
32: ; preds = %1
store i32 -1, i32* %2
br label %33
33: ; preds = %32, %31, %30, %29, %28, %27, %26, %25, %24, %23, %22, %21, %20, %19, %18, %17, %16, %15, %14, %13, %12, %11, %10, %9, %8, %7, %6
%34 = load i32, i32* %2
ret i32 %34
}

LLVM IR (-O2):
define i32 @letter_num(i8 signext %0) {
%2 = tail call i32 @toupper(i8 signext %0)
%3 = add i32 %2, -65
%4 = icmp ult i32 %3, 26
%5 = select i1 %4, i32 %3, i32 -1
ret i32 %5
}