unsigned char to_amino_acid_off(char c) {
  switch (c) {
  case 'A':
    return 0;
  case 'C':
    return 1;
  case 'D':
    return 2;
  case 'E':
    return 3;
  case 'F':
    return 4;
  case 'G':
    return 5;
  case 'H':
    return 6;
  case 'I':
    return 7;
  case 'K':
    return 8;
  case 'L':
    return 9;
  case 'M':
    return 10;
  case 'N':
    return 11;
  case 'P':
    return 12;
  case 'Q':
    return 13;
  case 'R':
    return 14;
  case 'S':
    return 15;
  case 'T':
    return 16;
  case 'V':
    return 17;
  case 'W':
    return 18;
  case 'Y':
    return 19;
  default:
    return 20;
  }
}


x86 assembly (clang, -O0):
<to_amino_acid_off>:
push   %rbp
mov    %rsp,%rbp
mov    %dil,%al
mov    %al,-0x2(%rbp)
movsbl -0x2(%rbp),%eax
add    $0xffffffbf,%eax
mov    %eax,%ecx
mov    %rcx,-0x10(%rbp)
sub    $0x18,%eax
ja     11e8 <to_amino_acid_off+0xe8>
mov    -0x10(%rbp),%rax
lea    0xed5(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
movb   $0x0,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x1,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x2,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x3,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x4,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x5,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x6,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x7,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x8,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x9,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0xa,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0xb,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0xc,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0xd,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0xe,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0xf,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x10,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x11,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x12,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x13,-0x1(%rbp)
jmp    11ec <to_amino_acid_off+0xec>
movb   $0x14,-0x1(%rbp)
movzbl -0x1(%rbp),%eax
pop    %rbp
ret

x86 assembly (clang, -O2):
<to_amino_acid_off>:
movslq %edi,%rcx
add    $0xffffffffffffffbf,%rcx
mov    $0x14,%al
cmp    $0x18,%ecx
ja     1118 <to_amino_acid_off+0x18>
lea    0xeeb(%rip),%rax
mov    (%rcx,%rax,1),%al
ret

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

LLVM IR (-O2):
@switch.table.to_amino_acid_off = [25 x i8] c"\00\14\01\02\03\04\05\06\07\14\08\09\0A\0B\14\0C\0D\0E\0F\10\14\11\12\14\13"
define zeroext i8 @to_amino_acid_off(i8 signext %0) {
%2 = sext i8 %0 to i32
%3 = add nsw i32 %2, -65
%4 = icmp ult i32 %3, 25
br i1 %4, label %5, label %9
5: ; preds = %1
%6 = sext i32 %3 to i64
%7 = getelementptr inbounds [25 x i8], [25 x i8]* @switch.table.to_amino_acid_off, i64 0, i64 %6
%8 = load i8, i8* %7
br label %9
9: ; preds = %1, %5
%10 = phi i8 [ %8, %5 ], [ 20, %1 ]
ret i8 %10
}