int HexNumber(int c) {
  char s;
  switch (c) {
  case 0:
    s = '0';
    break;
  case 1:
    s = '1';
    break;
  case 2:
    s = '2';
    break;
  case 3:
    s = '3';
    break;
  case 4:
    s = '4';
    break;
  case 5:
    s = '5';
    break;
  case 6:
    s = '6';
    break;
  case 7:
    s = '7';
    break;
  case 8:
    s = '8';
    break;
  case 9:
    s = '9';
    break;
  case 10:
    s = 'A';
    break;
  case 11:
    s = 'B';
    break;
  case 12:
    s = 'C';
    break;
  case 13:
    s = 'D';
    break;
  case 14:
    s = 'E';
    break;
  case 15:
    s = 'F';
    break;
  default:
    s = '0';
  }
  return s;
}


x86 assembly (clang, -O0):
<HexNumber>:
push   %rbp
mov    %rsp,%rbp
mov    %edi,-0x4(%rbp)
mov    -0x4(%rbp),%eax
mov    %rax,-0x10(%rbp)
sub    $0xf,%rax
ja     11bc <HexNumber+0xbc>
mov    -0x10(%rbp),%rax
lea    0xedd(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
movb   $0x30,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x31,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x32,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x33,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x34,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x35,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x36,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x37,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x38,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x39,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x41,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x42,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x43,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x44,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x45,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x46,-0x5(%rbp)
jmp    11c0 <HexNumber+0xc0>
movb   $0x30,-0x5(%rbp)
movsbl -0x5(%rbp),%eax
pop    %rbp
ret

x86 assembly (clang, -O2):
<HexNumber>:
add    $0xffffffff,%edi
mov    $0x30,%eax
cmp    $0xe,%edi
ja     111a <HexNumber+0x1a>
movslq %edi,%rax
lea    0xee9(%rip),%rcx
mov    (%rcx,%rax,4),%eax
ret

LLVM IR (-O0):
define i32 @HexNumber(i32 %0) {
%2 = alloca i32
%3 = alloca i8
store i32 %0, i32* %2
%4 = load i32, i32* %2
switch i32 %4, label %21 [
i32 0, label %5
i32 1, label %6
i32 2, label %7
i32 3, label %8
i32 4, label %9
i32 5, label %10
i32 6, label %11
i32 7, label %12
i32 8, label %13
i32 9, label %14
i32 10, label %15
i32 11, label %16
i32 12, label %17
i32 13, label %18
i32 14, label %19
i32 15, label %20
]
5: ; preds = %1
store i8 48, i8* %3
br label %22
6: ; preds = %1
store i8 49, i8* %3
br label %22
7: ; preds = %1
store i8 50, i8* %3
br label %22
8: ; preds = %1
store i8 51, i8* %3
br label %22
9: ; preds = %1
store i8 52, i8* %3
br label %22
10: ; preds = %1
store i8 53, i8* %3
br label %22
11: ; preds = %1
store i8 54, i8* %3
br label %22
12: ; preds = %1
store i8 55, i8* %3
br label %22
13: ; preds = %1
store i8 56, i8* %3
br label %22
14: ; preds = %1
store i8 57, i8* %3
br label %22
15: ; preds = %1
store i8 65, i8* %3
br label %22
16: ; preds = %1
store i8 66, i8* %3
br label %22
17: ; preds = %1
store i8 67, i8* %3
br label %22
18: ; preds = %1
store i8 68, i8* %3
br label %22
19: ; preds = %1
store i8 69, i8* %3
br label %22
20: ; preds = %1
store i8 70, i8* %3
br label %22
21: ; preds = %1
store i8 48, i8* %3
br label %22
22: ; preds = %21, %20, %19, %18, %17, %16, %15, %14, %13, %12, %11, %10, %9, %8, %7, %6, %5
%23 = load i8, i8* %3
%24 = sext i8 %23 to i32
ret i32 %24
}

LLVM IR (-O2):
@switch.table.HexNumber = [15 x i32] [i32 49, i32 50, i32 51, i32 52, i32 53, i32 54, i32 55, i32 56, i32 57, i32 65, i32 66, i32 67, i32 68, i32 69, i32 70]
define i32 @HexNumber(i32 %0) {
%2 = add i32 %0, -1
%3 = icmp ult i32 %2, 15
br i1 %3, label %4, label %8
4: ; preds = %1
%5 = sext i32 %2 to i64
%6 = getelementptr inbounds [15 x i32], [15 x i32]* @switch.table.HexNumber, i64 0, i64 %5
%7 = load i32, i32* %6
br label %8
8: ; preds = %4, %1
%9 = phi i32 [ 48, %1 ], [ %7, %4 ]
ret i32 %9
}