char *clockstring(int clockid) {
  switch (clockid) {
  case 0:
    return "CLOCK_REALTIME";
  case 1:
    return "CLOCK_MONOTONIC";
  case 2:
    return "CLOCK_PROCESS_CPUTIME_ID";
  case 3:
    return "CLOCK_THREAD_CPUTIME_ID";
  case 4:
    return "CLOCK_MONOTONIC_RAW";
  case 5:
    return "CLOCK_REALTIME_COARSE";
  case 6:
    return "CLOCK_MONOTONIC_COARSE";
  case 7:
    return "CLOCK_BOOTTIME";
  case 8:
    return "CLOCK_REALTIME_ALARM";
  case 9:
    return "CLOCK_BOOTTIME_ALARM";
  case 11:
    return "CLOCK_TAI";
  };
  return "UNKNOWN_CLOCKID";
}


x86 assembly (clang, -O0):
<clockstring>:
push   %rbp
mov    %rsp,%rbp
mov    %edi,-0xc(%rbp)
mov    -0xc(%rbp),%eax
mov    %rax,-0x18(%rbp)
sub    $0xb,%rax
ja     11dc <clockstring+0xdc>
mov    -0x18(%rbp),%rax
lea    0xedd(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
lea    0xefd(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11e7 <clockstring+0xe7>
lea    0xefc(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11e7 <clockstring+0xe7>
lea    0xefc(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11e7 <clockstring+0xe7>
lea    0xf05(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11e7 <clockstring+0xe7>
lea    0xf0d(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11e7 <clockstring+0xe7>
lea    0xf11(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11e7 <clockstring+0xe7>
lea    0xf17(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11e7 <clockstring+0xe7>
lea    0xf1e(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11e7 <clockstring+0xe7>
lea    0xf1d(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11e7 <clockstring+0xe7>
lea    0xf22(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11e7 <clockstring+0xe7>
lea    0xf27(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11e7 <clockstring+0xe7>
lea    0xf21(%rip),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
pop    %rbp
ret

x86 assembly (clang, -O2):
<clockstring>:
cmp    $0xb,%edi
ja     1117 <clockstring+0x17>
movslq %edi,%rax
lea    0xfd5(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
ret
lea    0xfb6(%rip),%rax
ret

LLVM IR (-O0):
@.str = [15 x i8] c"CLOCK_REALTIME\00"
@.str.1 = [16 x i8] c"CLOCK_MONOTONIC\00"
@.str.2 = [25 x i8] c"CLOCK_PROCESS_CPUTIME_ID\00"
@.str.3 = [24 x i8] c"CLOCK_THREAD_CPUTIME_ID\00"
@.str.4 = [20 x i8] c"CLOCK_MONOTONIC_RAW\00"
@.str.5 = [22 x i8] c"CLOCK_REALTIME_COARSE\00"
@.str.6 = [23 x i8] c"CLOCK_MONOTONIC_COARSE\00"
@.str.7 = [15 x i8] c"CLOCK_BOOTTIME\00"
@.str.8 = [21 x i8] c"CLOCK_REALTIME_ALARM\00"
@.str.9 = [21 x i8] c"CLOCK_BOOTTIME_ALARM\00"
@.str.10 = [10 x i8] c"CLOCK_TAI\00"
@.str.11 = [16 x i8] c"UNKNOWN_CLOCKID\00"
define i8* @clockstring(i32 %0) {
%2 = alloca i8*
%3 = alloca i32
store i32 %0, i32* %3
%4 = load i32, i32* %3
switch i32 %4, label %16 [
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 11, label %15
]
5: ; preds = %1
store i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str, i64 0, i64 0), i8** %2
br label %17
6: ; preds = %1
store i8* getelementptr inbounds ([16 x i8], [16 x i8]* @.str.1, i64 0, i64 0), i8** %2
br label %17
7: ; preds = %1
store i8* getelementptr inbounds ([25 x i8], [25 x i8]* @.str.2, i64 0, i64 0), i8** %2
br label %17
8: ; preds = %1
store i8* getelementptr inbounds ([24 x i8], [24 x i8]* @.str.3, i64 0, i64 0), i8** %2
br label %17
9: ; preds = %1
store i8* getelementptr inbounds ([20 x i8], [20 x i8]* @.str.4, i64 0, i64 0), i8** %2
br label %17
10: ; preds = %1
store i8* getelementptr inbounds ([22 x i8], [22 x i8]* @.str.5, i64 0, i64 0), i8** %2
br label %17
11: ; preds = %1
store i8* getelementptr inbounds ([23 x i8], [23 x i8]* @.str.6, i64 0, i64 0), i8** %2
br label %17
12: ; preds = %1
store i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str.7, i64 0, i64 0), i8** %2
br label %17
13: ; preds = %1
store i8* getelementptr inbounds ([21 x i8], [21 x i8]* @.str.8, i64 0, i64 0), i8** %2
br label %17
14: ; preds = %1
store i8* getelementptr inbounds ([21 x i8], [21 x i8]* @.str.9, i64 0, i64 0), i8** %2
br label %17
15: ; preds = %1
store i8* getelementptr inbounds ([10 x i8], [10 x i8]* @.str.10, i64 0, i64 0), i8** %2
br label %17
16: ; preds = %1
store i8* getelementptr inbounds ([16 x i8], [16 x i8]* @.str.11, i64 0, i64 0), i8** %2
br label %17
17: ; preds = %16, %15, %14, %13, %12, %11, %10, %9, %8, %7, %6, %5
%18 = load i8*, i8** %2
ret i8* %18
}

LLVM IR (-O2):
@.str = [15 x i8] c"CLOCK_REALTIME\00"
@.str.1 = [16 x i8] c"CLOCK_MONOTONIC\00"
@.str.2 = [25 x i8] c"CLOCK_PROCESS_CPUTIME_ID\00"
@.str.3 = [24 x i8] c"CLOCK_THREAD_CPUTIME_ID\00"
@.str.4 = [20 x i8] c"CLOCK_MONOTONIC_RAW\00"
@.str.5 = [22 x i8] c"CLOCK_REALTIME_COARSE\00"
@.str.6 = [23 x i8] c"CLOCK_MONOTONIC_COARSE\00"
@.str.7 = [15 x i8] c"CLOCK_BOOTTIME\00"
@.str.8 = [21 x i8] c"CLOCK_REALTIME_ALARM\00"
@.str.9 = [21 x i8] c"CLOCK_BOOTTIME_ALARM\00"
@.str.10 = [10 x i8] c"CLOCK_TAI\00"
@.str.11 = [16 x i8] c"UNKNOWN_CLOCKID\00"
@reltable.clockstring = [12 x i32] [i32 trunc (i64 sub (i64 ptrtoint ([15 x i8]* @.str to i64), i64 ptrtoint ([12 x i32]* @reltable.clockstring to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([16 x i8]* @.str.1 to i64), i64 ptrtoint ([12 x i32]* @reltable.clockstring to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([25 x i8]* @.str.2 to i64), i64 ptrtoint ([12 x i32]* @reltable.clockstring to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([24 x i8]* @.str.3 to i64), i64 ptrtoint ([12 x i32]* @reltable.clockstring to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([20 x i8]* @.str.4 to i64), i64 ptrtoint ([12 x i32]* @reltable.clockstring to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([22 x i8]* @.str.5 to i64), i64 ptrtoint ([12 x i32]* @reltable.clockstring to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([23 x i8]* @.str.6 to i64), i64 ptrtoint ([12 x i32]* @reltable.clockstring to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([15 x i8]* @.str.7 to i64), i64 ptrtoint ([12 x i32]* @reltable.clockstring to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([21 x i8]* @.str.8 to i64), i64 ptrtoint ([12 x i32]* @reltable.clockstring to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([21 x i8]* @.str.9 to i64), i64 ptrtoint ([12 x i32]* @reltable.clockstring to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([16 x i8]* @.str.11 to i64), i64 ptrtoint ([12 x i32]* @reltable.clockstring to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([10 x i8]* @.str.10 to i64), i64 ptrtoint ([12 x i32]* @reltable.clockstring to i64)) to i32)]
define i8* @clockstring(i32 %0) {
%2 = icmp ult i32 %0, 12
br i1 %2, label %3, label %7
3: ; preds = %1
%4 = sext i32 %0 to i64
%5 = shl i64 %4, 2
%6 = call i8* @llvm.load.relative.i64(i8* bitcast ([12 x i32]* @reltable.clockstring to i8*), i64 %5)
br label %7
7: ; preds = %1, %3
%8 = phi i8* [ %6, %3 ], [ getelementptr inbounds ([16 x i8], [16 x i8]* @.str.11, i64 0, i64 0), %1 ]
ret i8* %8
}