const char *twopence_strerror(int rc) {
  switch (rc) {
  case -1:
    return "Invalid command parameter";
  case -2:
    return "Error opening the communication with the system under test";
  case -3:
    return "Error sending command to the system under test";
  case -4:
    return "Error forwarding keyboard input";
  case -5:
    return "Error receiving the results of action";
  case -6:
    return "Remote command took too long to execute";
  case -7:
    return "Local error while transferring file";
  case -8:
    return "Error sending file to the system under test";
  case -9:
    return "Remote error while transferring file";
  case -10:
    return "Error receiving file from the system under test";
  case -11:
    return "Failed to interrupt command";
  case -12:
    return "Invalid target specification";
  case -13:
    return "Unknown plugin";
  case -14:
    return "Incompatible plugin";
  case -15:
    return "Operation not supported by the plugin";
  case -16:
    return "Twopence custom protocol error";
  case -17:
    return "Internal error";
  case -18:
    return "Error sending or receiving data on socket";
  case -19:
    return "Protocol versions not compatible between client and server";
  case -20:
    return "Invalid transaction ID";
  case -21:
    return "Command canceled by user";
  }
  return "Unknow error";
}


x86 assembly (clang, -O0):
<twopence_strerror>:
push   %rbp
mov    %rsp,%rbp
mov    %edi,-0xc(%rbp)
mov    -0xc(%rbp),%eax
add    $0x15,%eax
mov    %eax,%ecx
mov    %rcx,-0x18(%rbp)
sub    $0x14,%eax
ja     1280 <twopence_strerror+0x180>
mov    -0x18(%rbp),%rax
lea    0xed9(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
lea    0xf1d(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0xf27(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0xf52(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0xf71(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0xf81(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0xf97(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0xfaf(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0xfc3(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0xfdf(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0xff4(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0x1014(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0x1020(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0x102d(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0x102c(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0x1030(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0x1046(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0x1055(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0x1054(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0x106e(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0x1099(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0x10a0(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    128b <twopence_strerror+0x18b>
lea    0x10a9(%rip),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
pop    %rbp
ret

x86 assembly (clang, -O2):
<twopence_strerror>:
cmp    $0xffffffeb,%edi
jb     111a <twopence_strerror+0x1a>
add    $0x15,%edi
movslq %edi,%rax
lea    0x11da(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
ret
lea    0x11bb(%rip),%rax
ret

LLVM IR (-O0):
@.str = [26 x i8] c"Invalid command parameter\00"
@.str.1 = [59 x i8] c"Error opening the communication with the system under test\00"
@.str.2 = [47 x i8] c"Error sending command to the system under test\00"
@.str.3 = [32 x i8] c"Error forwarding keyboard input\00"
@.str.4 = [38 x i8] c"Error receiving the results of action\00"
@.str.5 = [40 x i8] c"Remote command took too long to execute\00"
@.str.6 = [36 x i8] c"Local error while transferring file\00"
@.str.7 = [44 x i8] c"Error sending file to the system under test\00"
@.str.8 = [37 x i8] c"Remote error while transferring file\00"
@.str.9 = [48 x i8] c"Error receiving file from the system under test\00"
@.str.10 = [28 x i8] c"Failed to interrupt command\00"
@.str.11 = [29 x i8] c"Invalid target specification\00"
@.str.12 = [15 x i8] c"Unknown plugin\00"
@.str.13 = [20 x i8] c"Incompatible plugin\00"
@.str.14 = [38 x i8] c"Operation not supported by the plugin\00"
@.str.15 = [31 x i8] c"Twopence custom protocol error\00"
@.str.16 = [15 x i8] c"Internal error\00"
@.str.17 = [42 x i8] c"Error sending or receiving data on socket\00"
@.str.18 = [59 x i8] c"Protocol versions not compatible between client and server\00"
@.str.19 = [23 x i8] c"Invalid transaction ID\00"
@.str.20 = [25 x i8] c"Command canceled by user\00"
@.str.21 = [13 x i8] c"Unknow error\00"
define i8* @twopence_strerror(i32 %0) {
%2 = alloca i8*
%3 = alloca i32
store i32 %0, i32* %3
%4 = load i32, i32* %3
switch i32 %4, label %26 [
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
i32 -8, label %12
i32 -9, label %13
i32 -10, label %14
i32 -11, label %15
i32 -12, label %16
i32 -13, label %17
i32 -14, label %18
i32 -15, label %19
i32 -16, label %20
i32 -17, label %21
i32 -18, label %22
i32 -19, label %23
i32 -20, label %24
i32 -21, label %25
]
5: ; preds = %1
store i8* getelementptr inbounds ([26 x i8], [26 x i8]* @.str, i64 0, i64 0), i8** %2
br label %27
6: ; preds = %1
store i8* getelementptr inbounds ([59 x i8], [59 x i8]* @.str.1, i64 0, i64 0), i8** %2
br label %27
7: ; preds = %1
store i8* getelementptr inbounds ([47 x i8], [47 x i8]* @.str.2, i64 0, i64 0), i8** %2
br label %27
8: ; preds = %1
store i8* getelementptr inbounds ([32 x i8], [32 x i8]* @.str.3, i64 0, i64 0), i8** %2
br label %27
9: ; preds = %1
store i8* getelementptr inbounds ([38 x i8], [38 x i8]* @.str.4, i64 0, i64 0), i8** %2
br label %27
10: ; preds = %1
store i8* getelementptr inbounds ([40 x i8], [40 x i8]* @.str.5, i64 0, i64 0), i8** %2
br label %27
11: ; preds = %1
store i8* getelementptr inbounds ([36 x i8], [36 x i8]* @.str.6, i64 0, i64 0), i8** %2
br label %27
12: ; preds = %1
store i8* getelementptr inbounds ([44 x i8], [44 x i8]* @.str.7, i64 0, i64 0), i8** %2
br label %27
13: ; preds = %1
store i8* getelementptr inbounds ([37 x i8], [37 x i8]* @.str.8, i64 0, i64 0), i8** %2
br label %27
14: ; preds = %1
store i8* getelementptr inbounds ([48 x i8], [48 x i8]* @.str.9, i64 0, i64 0), i8** %2
br label %27
15: ; preds = %1
store i8* getelementptr inbounds ([28 x i8], [28 x i8]* @.str.10, i64 0, i64 0), i8** %2
br label %27
16: ; preds = %1
store i8* getelementptr inbounds ([29 x i8], [29 x i8]* @.str.11, i64 0, i64 0), i8** %2
br label %27
17: ; preds = %1
store i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str.12, i64 0, i64 0), i8** %2
br label %27
18: ; preds = %1
store i8* getelementptr inbounds ([20 x i8], [20 x i8]* @.str.13, i64 0, i64 0), i8** %2
br label %27
19: ; preds = %1
store i8* getelementptr inbounds ([38 x i8], [38 x i8]* @.str.14, i64 0, i64 0), i8** %2
br label %27
20: ; preds = %1
store i8* getelementptr inbounds ([31 x i8], [31 x i8]* @.str.15, i64 0, i64 0), i8** %2
br label %27
21: ; preds = %1
store i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str.16, i64 0, i64 0), i8** %2
br label %27
22: ; preds = %1
store i8* getelementptr inbounds ([42 x i8], [42 x i8]* @.str.17, i64 0, i64 0), i8** %2
br label %27
23: ; preds = %1
store i8* getelementptr inbounds ([59 x i8], [59 x i8]* @.str.18, i64 0, i64 0), i8** %2
br label %27
24: ; preds = %1
store i8* getelementptr inbounds ([23 x i8], [23 x i8]* @.str.19, i64 0, i64 0), i8** %2
br label %27
25: ; preds = %1
store i8* getelementptr inbounds ([25 x i8], [25 x i8]* @.str.20, i64 0, i64 0), i8** %2
br label %27
26: ; preds = %1
store i8* getelementptr inbounds ([13 x i8], [13 x i8]* @.str.21, i64 0, i64 0), i8** %2
br label %27
27: ; preds = %26, %25, %24, %23, %22, %21, %20, %19, %18, %17, %16, %15, %14, %13, %12, %11, %10, %9, %8, %7, %6, %5
%28 = load i8*, i8** %2
ret i8* %28
}

LLVM IR (-O2):
@.str = [26 x i8] c"Invalid command parameter\00"
@.str.1 = [59 x i8] c"Error opening the communication with the system under test\00"
@.str.2 = [47 x i8] c"Error sending command to the system under test\00"
@.str.3 = [32 x i8] c"Error forwarding keyboard input\00"
@.str.4 = [38 x i8] c"Error receiving the results of action\00"
@.str.5 = [40 x i8] c"Remote command took too long to execute\00"
@.str.6 = [36 x i8] c"Local error while transferring file\00"
@.str.7 = [44 x i8] c"Error sending file to the system under test\00"
@.str.8 = [37 x i8] c"Remote error while transferring file\00"
@.str.9 = [48 x i8] c"Error receiving file from the system under test\00"
@.str.10 = [28 x i8] c"Failed to interrupt command\00"
@.str.11 = [29 x i8] c"Invalid target specification\00"
@.str.12 = [15 x i8] c"Unknown plugin\00"
@.str.13 = [20 x i8] c"Incompatible plugin\00"
@.str.14 = [38 x i8] c"Operation not supported by the plugin\00"
@.str.15 = [31 x i8] c"Twopence custom protocol error\00"
@.str.16 = [15 x i8] c"Internal error\00"
@.str.17 = [42 x i8] c"Error sending or receiving data on socket\00"
@.str.18 = [59 x i8] c"Protocol versions not compatible between client and server\00"
@.str.19 = [23 x i8] c"Invalid transaction ID\00"
@.str.20 = [25 x i8] c"Command canceled by user\00"
@.str.21 = [13 x i8] c"Unknow error\00"
@reltable.twopence_strerror = [21 x i32] [i32 trunc (i64 sub (i64 ptrtoint ([25 x i8]* @.str.20 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([23 x i8]* @.str.19 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([59 x i8]* @.str.18 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([42 x i8]* @.str.17 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([15 x i8]* @.str.16 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([31 x i8]* @.str.15 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([38 x i8]* @.str.14 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([20 x i8]* @.str.13 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([15 x i8]* @.str.12 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([29 x i8]* @.str.11 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([28 x i8]* @.str.10 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([48 x i8]* @.str.9 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([37 x i8]* @.str.8 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([44 x i8]* @.str.7 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([36 x i8]* @.str.6 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([40 x i8]* @.str.5 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([38 x i8]* @.str.4 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([32 x i8]* @.str.3 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([47 x i8]* @.str.2 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([59 x i8]* @.str.1 to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([26 x i8]* @.str to i64), i64 ptrtoint ([21 x i32]* @reltable.twopence_strerror to i64)) to i32)]
define i8* @twopence_strerror(i32 %0) {
%2 = icmp ugt i32 %0, -22
br i1 %2, label %3, label %8
3: ; preds = %1
%4 = add i32 %0, 21
%5 = sext i32 %4 to i64
%6 = shl i64 %5, 2
%7 = call i8* @llvm.load.relative.i64(i8* bitcast ([21 x i32]* @reltable.twopence_strerror to i8*), i64 %6)
br label %8
8: ; preds = %1, %3
%9 = phi i8* [ %7, %3 ], [ getelementptr inbounds ([13 x i8], [13 x i8]* @.str.21, i64 0, i64 0), %1 ]
ret i8* %9
}