const char *sllq_strerror(int errnum) {
  switch (errnum) {
  case 0:
    return 0;
  case 1:
    return "generic error";
  case 2:
    return "system error";
  case 3:
    return "out of memory";
  case 4:
    return "invalid argument";
  case 5:
    return "timed out";
  case 6:
    return "busy";
  case 7:
    return "try again";
  case 8:
    return "queue is empty";
  case 9:
    return "queue is full";
  }
  return "UNKNOWN";
}


x86 assembly (clang, -O0):
<sllq_strerror>:
push   %rbp
mov    %rsp,%rbp
mov    %edi,-0xc(%rbp)
mov    -0xc(%rbp),%eax
mov    %rax,-0x18(%rbp)
sub    $0x9,%rax
ja     11c9 <sllq_strerror+0xc9>
mov    -0x18(%rbp),%rax
lea    0xedd(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
movq   $0x0,-0x8(%rbp)
jmp    11d4 <sllq_strerror+0xd4>
lea    0xee8(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11d4 <sllq_strerror+0xd4>
lea    0xee6(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11d4 <sllq_strerror+0xd4>
lea    0xee3(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11d4 <sllq_strerror+0xd4>
lea    0xee1(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11d4 <sllq_strerror+0xd4>
lea    0xee2(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11d4 <sllq_strerror+0xd4>
lea    0xedc(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11d4 <sllq_strerror+0xd4>
lea    0xed1(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11d4 <sllq_strerror+0xd4>
lea    0xecb(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11d4 <sllq_strerror+0xd4>
lea    0xeca(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11d4 <sllq_strerror+0xd4>
lea    0xec8(%rip),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
pop    %rbp
ret

x86 assembly (clang, -O2):
<sllq_strerror>:
cmp    $0x9,%edi
ja     1114 <sllq_strerror+0x14>
movslq %edi,%rax
lea    0x2cf1(%rip),%rcx
mov    (%rcx,%rax,8),%rax
ret
lea    0xf55(%rip),%rax
ret

LLVM IR (-O0):
@.str = [14 x i8] c"generic error\00"
@.str.1 = [13 x i8] c"system error\00"
@.str.2 = [14 x i8] c"out of memory\00"
@.str.3 = [17 x i8] c"invalid argument\00"
@.str.4 = [10 x i8] c"timed out\00"
@.str.5 = [5 x i8] c"busy\00"
@.str.6 = [10 x i8] c"try again\00"
@.str.7 = [15 x i8] c"queue is empty\00"
@.str.8 = [14 x i8] c"queue is full\00"
@.str.9 = [8 x i8] c"UNKNOWN\00"
define i8* @sllq_strerror(i32 %0) {
%2 = alloca i8*
%3 = alloca i32
store i32 %0, i32* %3
%4 = load i32, i32* %3
switch i32 %4, label %15 [
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
]
5: ; preds = %1
store i8* null, i8** %2
br label %16
6: ; preds = %1
store i8* getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i8** %2
br label %16
7: ; preds = %1
store i8* getelementptr inbounds ([13 x i8], [13 x i8]* @.str.1, i64 0, i64 0), i8** %2
br label %16
8: ; preds = %1
store i8* getelementptr inbounds ([14 x i8], [14 x i8]* @.str.2, i64 0, i64 0), i8** %2
br label %16
9: ; preds = %1
store i8* getelementptr inbounds ([17 x i8], [17 x i8]* @.str.3, i64 0, i64 0), i8** %2
br label %16
10: ; preds = %1
store i8* getelementptr inbounds ([10 x i8], [10 x i8]* @.str.4, i64 0, i64 0), i8** %2
br label %16
11: ; preds = %1
store i8* getelementptr inbounds ([5 x i8], [5 x i8]* @.str.5, i64 0, i64 0), i8** %2
br label %16
12: ; preds = %1
store i8* getelementptr inbounds ([10 x i8], [10 x i8]* @.str.6, i64 0, i64 0), i8** %2
br label %16
13: ; preds = %1
store i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str.7, i64 0, i64 0), i8** %2
br label %16
14: ; preds = %1
store i8* getelementptr inbounds ([14 x i8], [14 x i8]* @.str.8, i64 0, i64 0), i8** %2
br label %16
15: ; preds = %1
store i8* getelementptr inbounds ([8 x i8], [8 x i8]* @.str.9, i64 0, i64 0), i8** %2
br label %16
16: ; preds = %15, %14, %13, %12, %11, %10, %9, %8, %7, %6, %5
%17 = load i8*, i8** %2
ret i8* %17
}

LLVM IR (-O2):
@.str = [14 x i8] c"generic error\00"
@.str.1 = [13 x i8] c"system error\00"
@.str.2 = [14 x i8] c"out of memory\00"
@.str.3 = [17 x i8] c"invalid argument\00"
@.str.4 = [10 x i8] c"timed out\00"
@.str.5 = [5 x i8] c"busy\00"
@.str.6 = [10 x i8] c"try again\00"
@.str.7 = [15 x i8] c"queue is empty\00"
@.str.8 = [14 x i8] c"queue is full\00"
@.str.9 = [8 x i8] c"UNKNOWN\00"
@switch.table.sllq_strerror = [10 x i8*] [i8* null, i8* getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0), i8* getelementptr inbounds ([13 x i8], [13 x i8]* @.str.1, i64 0, i64 0), i8* getelementptr inbounds ([14 x i8], [14 x i8]* @.str.2, i64 0, i64 0), i8* getelementptr inbounds ([17 x i8], [17 x i8]* @.str.3, i64 0, i64 0), i8* getelementptr inbounds ([10 x i8], [10 x i8]* @.str.4, i64 0, i64 0), i8* getelementptr inbounds ([5 x i8], [5 x i8]* @.str.5, i64 0, i64 0), i8* getelementptr inbounds ([10 x i8], [10 x i8]* @.str.6, i64 0, i64 0), i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str.7, i64 0, i64 0), i8* getelementptr inbounds ([14 x i8], [14 x i8]* @.str.8, i64 0, i64 0)]
define i8* @sllq_strerror(i32 %0) {
%2 = icmp ult i32 %0, 10
br i1 %2, label %3, label %7
3: ; preds = %1
%4 = sext i32 %0 to i64
%5 = getelementptr inbounds [10 x i8*], [10 x i8*]* @switch.table.sllq_strerror, i64 0, i64 %4
%6 = load i8*, i8** %5
br label %7
7: ; preds = %1, %3
%8 = phi i8* [ %6, %3 ], [ getelementptr inbounds ([8 x i8], [8 x i8]* @.str.9, i64 0, i64 0), %1 ]
ret i8* %8
}