const char *GetColorType(unsigned char code) {
  switch (code) {
  case 0:
    return "Greyscale";
  case 2:
    return "Truecolour";
  case 3:
    return "Indexed-colour";
  case 4:
    return "Greyscale with alpha";
  case 6:
    return "Truecolour with alpha";
  default:
    return "Unknown color type";
  }
}


x86 assembly (clang, -O0):
<GetColorType>:
push   %rbp
mov    %rsp,%rbp
mov    %dil,%al
mov    %al,-0x9(%rbp)
movzbl -0x9(%rbp),%eax
mov    %rax,-0x18(%rbp)
sub    $0x6,%rax
ja     1180 <GetColorType+0x80>
mov    -0x18(%rbp),%rax
lea    0xed9(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
lea    0xee5(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    118b <GetColorType+0x8b>
lea    0xedf(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    118b <GetColorType+0x8b>
lea    0xeda(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    118b <GetColorType+0x8b>
lea    0xed9(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    118b <GetColorType+0x8b>
lea    0xede(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    118b <GetColorType+0x8b>
lea    0xee4(%rip),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
pop    %rbp
ret

x86 assembly (clang, -O2):
<GetColorType>:
cmp    $0x6,%dil
ja     1119 <GetColorType+0x19>
movsbq %dil,%rax
lea    0xf53(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
ret
lea    0xf2f(%rip),%rax
ret

LLVM IR (-O0):
@.str = [10 x i8] c"Greyscale\00"
@.str.1 = [11 x i8] c"Truecolour\00"
@.str.2 = [15 x i8] c"Indexed-colour\00"
@.str.3 = [21 x i8] c"Greyscale with alpha\00"
@.str.4 = [22 x i8] c"Truecolour with alpha\00"
@.str.5 = [19 x i8] c"Unknown color type\00"
define i8* @GetColorType(i8 zeroext %0) {
%2 = alloca i8*
%3 = alloca i8
store i8 %0, i8* %3
%4 = load i8, i8* %3
%5 = zext i8 %4 to i32
switch i32 %5, label %11 [
i32 0, label %6
i32 2, label %7
i32 3, label %8
i32 4, label %9
i32 6, label %10
]
6: ; preds = %1
store i8* getelementptr inbounds ([10 x i8], [10 x i8]* @.str, i64 0, i64 0), i8** %2
br label %12
7: ; preds = %1
store i8* getelementptr inbounds ([11 x i8], [11 x i8]* @.str.1, i64 0, i64 0), i8** %2
br label %12
8: ; preds = %1
store i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str.2, i64 0, i64 0), i8** %2
br label %12
9: ; preds = %1
store i8* getelementptr inbounds ([21 x i8], [21 x i8]* @.str.3, i64 0, i64 0), i8** %2
br label %12
10: ; preds = %1
store i8* getelementptr inbounds ([22 x i8], [22 x i8]* @.str.4, i64 0, i64 0), i8** %2
br label %12
11: ; preds = %1
store i8* getelementptr inbounds ([19 x i8], [19 x i8]* @.str.5, i64 0, i64 0), i8** %2
br label %12
12: ; preds = %11, %10, %9, %8, %7, %6
%13 = load i8*, i8** %2
ret i8* %13
}

LLVM IR (-O2):
@.str = [10 x i8] c"Greyscale\00"
@.str.1 = [11 x i8] c"Truecolour\00"
@.str.2 = [15 x i8] c"Indexed-colour\00"
@.str.3 = [21 x i8] c"Greyscale with alpha\00"
@.str.4 = [22 x i8] c"Truecolour with alpha\00"
@.str.5 = [19 x i8] c"Unknown color type\00"
@reltable.GetColorType = [7 x i32] [i32 trunc (i64 sub (i64 ptrtoint ([10 x i8]* @.str to i64), i64 ptrtoint ([7 x i32]* @reltable.GetColorType to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([19 x i8]* @.str.5 to i64), i64 ptrtoint ([7 x i32]* @reltable.GetColorType to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([11 x i8]* @.str.1 to i64), i64 ptrtoint ([7 x i32]* @reltable.GetColorType to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([15 x i8]* @.str.2 to i64), i64 ptrtoint ([7 x i32]* @reltable.GetColorType to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([21 x i8]* @.str.3 to i64), i64 ptrtoint ([7 x i32]* @reltable.GetColorType to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([19 x i8]* @.str.5 to i64), i64 ptrtoint ([7 x i32]* @reltable.GetColorType to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([22 x i8]* @.str.4 to i64), i64 ptrtoint ([7 x i32]* @reltable.GetColorType to i64)) to i32)]
define i8* @GetColorType(i8 zeroext %0) {
%2 = icmp ult i8 %0, 7
br i1 %2, label %3, label %7
3: ; preds = %1
%4 = sext i8 %0 to i64
%5 = shl i64 %4, 2
%6 = call i8* @llvm.load.relative.i64(i8* bitcast ([7 x i32]* @reltable.GetColorType to i8*), i64 %5)
br label %7
7: ; preds = %1, %3
%8 = phi i8* [ %6, %3 ], [ getelementptr inbounds ([19 x i8], [19 x i8]* @.str.5, i64 0, i64 0), %1 ]
ret i8* %8
}