char *picmg_chan_type(unsigned char b) {
  char *s;
  switch (b) {
  case 0x00:
  case 0x07:
    s = "PICMG 2.9";
    break;
  case 0x08:
    s = "Single Port Fabric IF";
    break;
  case 0x09:
    s = "Double Port Fabric IF";
    break;
  case 0x0a:
    s = "Full Port Fabric IF";
    break;
  case 0x0b:
    s = "Base IF";
    break;
  case 0x0c:
    s = "Update Channel IF";
    break;
  default:
    s = "Unknown IF";
    break;
  }
  return (s);
}


x86 assembly (clang, -O0):
<picmg_chan_type>:
push   %rbp
mov    %rsp,%rbp
mov    %dil,%al
mov    %al,-0x1(%rbp)
movzbl -0x1(%rbp),%eax
mov    %rax,-0x18(%rbp)
sub    $0xc,%rax
ja     1190 <picmg_chan_type+0x90>
mov    -0x18(%rbp),%rax
lea    0xed9(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
lea    0xefd(%rip),%rax
mov    %rax,-0x10(%rbp)
jmp    119b <picmg_chan_type+0x9b>
lea    0xef7(%rip),%rax
mov    %rax,-0x10(%rbp)
jmp    119b <picmg_chan_type+0x9b>
lea    0xefd(%rip),%rax
mov    %rax,-0x10(%rbp)
jmp    119b <picmg_chan_type+0x9b>
lea    0xf03(%rip),%rax
mov    %rax,-0x10(%rbp)
jmp    119b <picmg_chan_type+0x9b>
lea    0xf07(%rip),%rax
mov    %rax,-0x10(%rbp)
jmp    119b <picmg_chan_type+0x9b>
lea    0xeff(%rip),%rax
mov    %rax,-0x10(%rbp)
jmp    119b <picmg_chan_type+0x9b>
lea    0xf01(%rip),%rax
mov    %rax,-0x10(%rbp)
mov    -0x10(%rbp),%rax
pop    %rbp
ret

x86 assembly (clang, -O2):
<picmg_chan_type>:
cmp    $0xc,%dil
ja     1119 <picmg_chan_type+0x19>
movsbq %dil,%rax
lea    0xf5f(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
ret
lea    0xf44(%rip),%rax
ret

LLVM IR (-O0):
@.str = [10 x i8] c"PICMG 2.9\00"
@.str.1 = [22 x i8] c"Single Port Fabric IF\00"
@.str.2 = [22 x i8] c"Double Port Fabric IF\00"
@.str.3 = [20 x i8] c"Full Port Fabric IF\00"
@.str.4 = [8 x i8] c"Base IF\00"
@.str.5 = [18 x i8] c"Update Channel IF\00"
@.str.6 = [11 x i8] c"Unknown IF\00"
define i8* @picmg_chan_type(i8 zeroext %0) {
%2 = alloca i8
%3 = alloca i8*
store i8 %0, i8* %2
%4 = load i8, i8* %2
%5 = zext i8 %4 to i32
switch i32 %5, label %12 [
i32 0, label %6
i32 7, label %6
i32 8, label %7
i32 9, label %8
i32 10, label %9
i32 11, label %10
i32 12, label %11
]
6: ; preds = %1, %1
store i8* getelementptr inbounds ([10 x i8], [10 x i8]* @.str, i64 0, i64 0), i8** %3
br label %13
7: ; preds = %1
store i8* getelementptr inbounds ([22 x i8], [22 x i8]* @.str.1, i64 0, i64 0), i8** %3
br label %13
8: ; preds = %1
store i8* getelementptr inbounds ([22 x i8], [22 x i8]* @.str.2, i64 0, i64 0), i8** %3
br label %13
9: ; preds = %1
store i8* getelementptr inbounds ([20 x i8], [20 x i8]* @.str.3, i64 0, i64 0), i8** %3
br label %13
10: ; preds = %1
store i8* getelementptr inbounds ([8 x i8], [8 x i8]* @.str.4, i64 0, i64 0), i8** %3
br label %13
11: ; preds = %1
store i8* getelementptr inbounds ([18 x i8], [18 x i8]* @.str.5, i64 0, i64 0), i8** %3
br label %13
12: ; preds = %1
store i8* getelementptr inbounds ([11 x i8], [11 x i8]* @.str.6, i64 0, i64 0), i8** %3
br label %13
13: ; preds = %12, %11, %10, %9, %8, %7, %6
%14 = load i8*, i8** %3
ret i8* %14
}

LLVM IR (-O2):
@.str = [10 x i8] c"PICMG 2.9\00"
@.str.1 = [22 x i8] c"Single Port Fabric IF\00"
@.str.2 = [22 x i8] c"Double Port Fabric IF\00"
@.str.3 = [20 x i8] c"Full Port Fabric IF\00"
@.str.4 = [8 x i8] c"Base IF\00"
@.str.5 = [18 x i8] c"Update Channel IF\00"
@.str.6 = [11 x i8] c"Unknown IF\00"
@reltable.picmg_chan_type = [13 x i32] [i32 trunc (i64 sub (i64 ptrtoint ([10 x i8]* @.str to i64), i64 ptrtoint ([13 x i32]* @reltable.picmg_chan_type to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([11 x i8]* @.str.6 to i64), i64 ptrtoint ([13 x i32]* @reltable.picmg_chan_type to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([11 x i8]* @.str.6 to i64), i64 ptrtoint ([13 x i32]* @reltable.picmg_chan_type to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([11 x i8]* @.str.6 to i64), i64 ptrtoint ([13 x i32]* @reltable.picmg_chan_type to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([11 x i8]* @.str.6 to i64), i64 ptrtoint ([13 x i32]* @reltable.picmg_chan_type to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([11 x i8]* @.str.6 to i64), i64 ptrtoint ([13 x i32]* @reltable.picmg_chan_type to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([11 x i8]* @.str.6 to i64), i64 ptrtoint ([13 x i32]* @reltable.picmg_chan_type to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([10 x i8]* @.str to i64), i64 ptrtoint ([13 x i32]* @reltable.picmg_chan_type to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([22 x i8]* @.str.1 to i64), i64 ptrtoint ([13 x i32]* @reltable.picmg_chan_type to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([22 x i8]* @.str.2 to i64), i64 ptrtoint ([13 x i32]* @reltable.picmg_chan_type to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([20 x i8]* @.str.3 to i64), i64 ptrtoint ([13 x i32]* @reltable.picmg_chan_type to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([8 x i8]* @.str.4 to i64), i64 ptrtoint ([13 x i32]* @reltable.picmg_chan_type to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([18 x i8]* @.str.5 to i64), i64 ptrtoint ([13 x i32]* @reltable.picmg_chan_type to i64)) to i32)]
define i8* @picmg_chan_type(i8 zeroext %0) {
%2 = icmp ult i8 %0, 13
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 ([13 x i32]* @reltable.picmg_chan_type to i8*), i64 %5)
br label %7
7: ; preds = %1, %3
%8 = phi i8* [ %6, %3 ], [ getelementptr inbounds ([11 x i8], [11 x i8]* @.str.6, i64 0, i64 0), %1 ]
ret i8* %8
}