const char *gai_strerror(int err) {
  switch (err) {
  case 1:
    return ("address family for host not supported");
  case 2:
    return ("temporary failure in name resolution");
  case 3:
    return ("invalid flags value");
  case 4:
    return ("non-recoverable failure in name resolution");
  case 5:
    return ("address family not supported");
  case 6:
    return ("memory allocation failure");
  case 7:
    return ("no address associated with host");
  case 8:
    return ("host nor service provided, or not known");
  case 9:
    return ("service not supported for socket type");
  case 10:
    return ("socket type not supported");
  case 11:
    return ("system error");
  default:
    return ("unknown getaddrinfo() error");
  }
}


x86 assembly (clang, -O0):
<gai_strerror>:
push   %rbp
mov    %rsp,%rbp
mov    %edi,-0xc(%rbp)
mov    -0xc(%rbp),%eax
add    $0xffffffff,%eax
mov    %eax,%ecx
mov    %rcx,-0x18(%rbp)
sub    $0xa,%eax
ja     11e0 <gai_strerror+0xe0>
mov    -0x18(%rbp),%rax
lea    0xed9(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
lea    0xef5(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11eb <gai_strerror+0xeb>
lea    0xf0b(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11eb <gai_strerror+0xeb>
lea    0xf20(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11eb <gai_strerror+0xeb>
lea    0xf24(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11eb <gai_strerror+0xeb>
lea    0xf3f(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11eb <gai_strerror+0xeb>
lea    0xf4c(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11eb <gai_strerror+0xeb>
lea    0xf56(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11eb <gai_strerror+0xeb>
lea    0xf66(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11eb <gai_strerror+0xeb>
lea    0xf7e(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11eb <gai_strerror+0xeb>
lea    0xf94(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11eb <gai_strerror+0xeb>
lea    0xf9e(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11eb <gai_strerror+0xeb>
lea    0xf9b(%rip),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
pop    %rbp
ret

x86 assembly (clang, -O2):
<gai_strerror>:
add    $0xffffffff,%edi
cmp    $0xa,%edi
ja     111a <gai_strerror+0x1a>
movslq %edi,%rax
lea    0x1062(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
ret
lea    0x1035(%rip),%rax
ret

LLVM IR (-O0):
@.str = [38 x i8] c"address family for host not supported\00"
@.str.1 = [37 x i8] c"temporary failure in name resolution\00"
@.str.2 = [20 x i8] c"invalid flags value\00"
@.str.3 = [43 x i8] c"non-recoverable failure in name resolution\00"
@.str.4 = [29 x i8] c"address family not supported\00"
@.str.5 = [26 x i8] c"memory allocation failure\00"
@.str.6 = [32 x i8] c"no address associated with host\00"
@.str.7 = [40 x i8] c"host nor service provided, or not known\00"
@.str.8 = [38 x i8] c"service not supported for socket type\00"
@.str.9 = [26 x i8] c"socket type not supported\00"
@.str.10 = [13 x i8] c"system error\00"
@.str.11 = [28 x i8] c"unknown getaddrinfo() error\00"
define i8* @gai_strerror(i32 %0) {
%2 = alloca i8*
%3 = alloca i32
store i32 %0, i32* %3
%4 = load i32, i32* %3
switch i32 %4, label %16 [
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
]
5: ; preds = %1
store i8* getelementptr inbounds ([38 x i8], [38 x i8]* @.str, i64 0, i64 0), i8** %2
br label %17
6: ; preds = %1
store i8* getelementptr inbounds ([37 x i8], [37 x i8]* @.str.1, i64 0, i64 0), i8** %2
br label %17
7: ; preds = %1
store i8* getelementptr inbounds ([20 x i8], [20 x i8]* @.str.2, i64 0, i64 0), i8** %2
br label %17
8: ; preds = %1
store i8* getelementptr inbounds ([43 x i8], [43 x i8]* @.str.3, i64 0, i64 0), i8** %2
br label %17
9: ; preds = %1
store i8* getelementptr inbounds ([29 x i8], [29 x i8]* @.str.4, i64 0, i64 0), i8** %2
br label %17
10: ; preds = %1
store i8* getelementptr inbounds ([26 x i8], [26 x i8]* @.str.5, i64 0, i64 0), i8** %2
br label %17
11: ; preds = %1
store i8* getelementptr inbounds ([32 x i8], [32 x i8]* @.str.6, i64 0, i64 0), i8** %2
br label %17
12: ; preds = %1
store i8* getelementptr inbounds ([40 x i8], [40 x i8]* @.str.7, i64 0, i64 0), i8** %2
br label %17
13: ; preds = %1
store i8* getelementptr inbounds ([38 x i8], [38 x i8]* @.str.8, i64 0, i64 0), i8** %2
br label %17
14: ; preds = %1
store i8* getelementptr inbounds ([26 x i8], [26 x i8]* @.str.9, i64 0, i64 0), i8** %2
br label %17
15: ; preds = %1
store i8* getelementptr inbounds ([13 x i8], [13 x i8]* @.str.10, i64 0, i64 0), i8** %2
br label %17
16: ; preds = %1
store i8* getelementptr inbounds ([28 x i8], [28 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 = [38 x i8] c"address family for host not supported\00"
@.str.1 = [37 x i8] c"temporary failure in name resolution\00"
@.str.2 = [20 x i8] c"invalid flags value\00"
@.str.3 = [43 x i8] c"non-recoverable failure in name resolution\00"
@.str.4 = [29 x i8] c"address family not supported\00"
@.str.5 = [26 x i8] c"memory allocation failure\00"
@.str.6 = [32 x i8] c"no address associated with host\00"
@.str.7 = [40 x i8] c"host nor service provided, or not known\00"
@.str.8 = [38 x i8] c"service not supported for socket type\00"
@.str.9 = [26 x i8] c"socket type not supported\00"
@.str.10 = [13 x i8] c"system error\00"
@.str.11 = [28 x i8] c"unknown getaddrinfo() error\00"
@reltable.gai_strerror = [11 x i32] [i32 trunc (i64 sub (i64 ptrtoint ([38 x i8]* @.str to i64), i64 ptrtoint ([11 x i32]* @reltable.gai_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([37 x i8]* @.str.1 to i64), i64 ptrtoint ([11 x i32]* @reltable.gai_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([20 x i8]* @.str.2 to i64), i64 ptrtoint ([11 x i32]* @reltable.gai_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([43 x i8]* @.str.3 to i64), i64 ptrtoint ([11 x i32]* @reltable.gai_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([29 x i8]* @.str.4 to i64), i64 ptrtoint ([11 x i32]* @reltable.gai_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([26 x i8]* @.str.5 to i64), i64 ptrtoint ([11 x i32]* @reltable.gai_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([32 x i8]* @.str.6 to i64), i64 ptrtoint ([11 x i32]* @reltable.gai_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([40 x i8]* @.str.7 to i64), i64 ptrtoint ([11 x i32]* @reltable.gai_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([38 x i8]* @.str.8 to i64), i64 ptrtoint ([11 x i32]* @reltable.gai_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([26 x i8]* @.str.9 to i64), i64 ptrtoint ([11 x i32]* @reltable.gai_strerror to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([13 x i8]* @.str.10 to i64), i64 ptrtoint ([11 x i32]* @reltable.gai_strerror to i64)) to i32)]
define i8* @gai_strerror(i32 %0) {
%2 = add i32 %0, -1
%3 = icmp ult i32 %2, 11
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 ([11 x i32]* @reltable.gai_strerror to i8*), i64 %6)
br label %8
8: ; preds = %1, %4
%9 = phi i8* [ %7, %4 ], [ getelementptr inbounds ([28 x i8], [28 x i8]* @.str.11, i64 0, i64 0), %1 ]
ret i8* %9
}