const char *ce_str(int encoding) {
  switch (encoding) {
  case 0x01:
    return "base64";
  case 0x02:
    return "quoted-printable";
  case 0x03:
    return "8bit";
  case 0x04:
    return "7bit";
  case 0x05:
    return "binary";
  case 0x06:
    return "extension";
  case 0x07:
    return "external";
  default:
    return "unknown";
  }
}


x86 assembly (clang, -O0):
<ce_str>:
push   %rbp
mov    %rsp,%rbp
mov    %edi,-0xc(%rbp)
mov    -0xc(%rbp),%eax
add    $0xffffffff,%eax
mov    %eax,%ecx
mov    %rcx,-0x18(%rbp)
sub    $0x6,%eax
ja     11a0 <ce_str+0xa0>
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    11ab <ce_str+0xab>
lea    0xedc(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11ab <ce_str+0xab>
lea    0xedd(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11ab <ce_str+0xab>
lea    0xed2(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11ab <ce_str+0xab>
lea    0xec7(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11ab <ce_str+0xab>
lea    0xebe(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11ab <ce_str+0xab>
lea    0xeb8(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11ab <ce_str+0xab>
lea    0xeb1(%rip),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
pop    %rbp
ret

x86 assembly (clang, -O2):
<ce_str>:
add    $0xffffffff,%edi
cmp    $0x6,%edi
ja     111a <ce_str+0x1a>
movslq %edi,%rax
lea    0xf32(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
ret
lea    0xf1b(%rip),%rax
ret

LLVM IR (-O0):
@.str = [7 x i8] c"base64\00"
@.str.1 = [17 x i8] c"quoted-printable\00"
@.str.2 = [5 x i8] c"8bit\00"
@.str.3 = [5 x i8] c"7bit\00"
@.str.4 = [7 x i8] c"binary\00"
@.str.5 = [10 x i8] c"extension\00"
@.str.6 = [9 x i8] c"external\00"
@.str.7 = [8 x i8] c"unknown\00"
define i8* @ce_str(i32 %0) {
%2 = alloca i8*
%3 = alloca i32
store i32 %0, i32* %3
%4 = load i32, i32* %3
switch i32 %4, label %12 [
i32 1, label %5
i32 2, label %6
i32 3, label %7
i32 4, label %8
i32 5, label %9
i32 6, label %10
i32 7, label %11
]
5: ; preds = %1
store i8* getelementptr inbounds ([7 x i8], [7 x i8]* @.str, i64 0, i64 0), i8** %2
br label %13
6: ; preds = %1
store i8* getelementptr inbounds ([17 x i8], [17 x i8]* @.str.1, i64 0, i64 0), i8** %2
br label %13
7: ; preds = %1
store i8* getelementptr inbounds ([5 x i8], [5 x i8]* @.str.2, i64 0, i64 0), i8** %2
br label %13
8: ; preds = %1
store i8* getelementptr inbounds ([5 x i8], [5 x i8]* @.str.3, i64 0, i64 0), i8** %2
br label %13
9: ; preds = %1
store i8* getelementptr inbounds ([7 x i8], [7 x i8]* @.str.4, i64 0, i64 0), i8** %2
br label %13
10: ; preds = %1
store i8* getelementptr inbounds ([10 x i8], [10 x i8]* @.str.5, i64 0, i64 0), i8** %2
br label %13
11: ; preds = %1
store i8* getelementptr inbounds ([9 x i8], [9 x i8]* @.str.6, i64 0, i64 0), i8** %2
br label %13
12: ; preds = %1
store i8* getelementptr inbounds ([8 x i8], [8 x i8]* @.str.7, i64 0, i64 0), i8** %2
br label %13
13: ; preds = %12, %11, %10, %9, %8, %7, %6, %5
%14 = load i8*, i8** %2
ret i8* %14
}

LLVM IR (-O2):
@.str = [7 x i8] c"base64\00"
@.str.1 = [17 x i8] c"quoted-printable\00"
@.str.2 = [5 x i8] c"8bit\00"
@.str.3 = [5 x i8] c"7bit\00"
@.str.4 = [7 x i8] c"binary\00"
@.str.5 = [10 x i8] c"extension\00"
@.str.6 = [9 x i8] c"external\00"
@.str.7 = [8 x i8] c"unknown\00"
@reltable.ce_str = [7 x i32] [i32 trunc (i64 sub (i64 ptrtoint ([7 x i8]* @.str to i64), i64 ptrtoint ([7 x i32]* @reltable.ce_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([17 x i8]* @.str.1 to i64), i64 ptrtoint ([7 x i32]* @reltable.ce_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([5 x i8]* @.str.2 to i64), i64 ptrtoint ([7 x i32]* @reltable.ce_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([5 x i8]* @.str.3 to i64), i64 ptrtoint ([7 x i32]* @reltable.ce_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([7 x i8]* @.str.4 to i64), i64 ptrtoint ([7 x i32]* @reltable.ce_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([10 x i8]* @.str.5 to i64), i64 ptrtoint ([7 x i32]* @reltable.ce_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([9 x i8]* @.str.6 to i64), i64 ptrtoint ([7 x i32]* @reltable.ce_str to i64)) to i32)]
define i8* @ce_str(i32 %0) {
%2 = add i32 %0, -1
%3 = icmp ult i32 %2, 7
br i1 %3, label %4, label %8
4: ; preds = %1
%5 = sext i32 %2 to i64
%6 = shl i64 %5, 2
%7 = call i8* @llvm.load.relative.i64(i8* bitcast ([7 x i32]* @reltable.ce_str to i8*), i64 %6)
br label %8
8: ; preds = %1, %4
%9 = phi i8* [ %7, %4 ], [ getelementptr inbounds ([8 x i8], [8 x i8]* @.str.7, i64 0, i64 0), %1 ]
ret i8* %9
}