char *icspio_err(int err) {
  static char *errmsg;
  switch (err) {
  case (0):
    errmsg = "ERRNONE";
    break;
  case (1):
    errmsg = "ERRTIMEOUT";
    break;
  case (2):
    errmsg = "ERRPROTOCOL";
    break;
  case (3):
    errmsg = "ERRPARITY";
    break;
  case (4):
    errmsg = "ERRNOTSUP";
    break;
  case (5):
    errmsg = "ERRINVALID";
    break;
  default:
    errmsg = "ERRUNKNOWN";
    break;
  }
  return errmsg;
}


x86 assembly (clang, -O0):
<icspio_err>:
push   %rbp
mov    %rsp,%rbp
mov    %edi,-0x4(%rbp)
mov    -0x4(%rbp),%eax
mov    %rax,-0x10(%rbp)
sub    $0x5,%rax
ja     119e <icspio_err+0x9e>
mov    -0x10(%rbp),%rax
lea    0xedd(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
lea    0xee5(%rip),%rax
mov    %rax,0x2eee(%rip)
jmp    11ac <icspio_err+0xac>
lea    0xeda(%rip),%rax
mov    %rax,0x2edb(%rip)
jmp    11ac <icspio_err+0xac>
lea    0xed2(%rip),%rax
mov    %rax,0x2ec8(%rip)
jmp    11ac <icspio_err+0xac>
lea    0xecb(%rip),%rax
mov    %rax,0x2eb5(%rip)
jmp    11ac <icspio_err+0xac>
lea    0xec2(%rip),%rax
mov    %rax,0x2ea2(%rip)
jmp    11ac <icspio_err+0xac>
lea    0xeb9(%rip),%rax
mov    %rax,0x2e8f(%rip)
jmp    11ac <icspio_err+0xac>
lea    0xeb1(%rip),%rax
mov    %rax,0x2e7c(%rip)
mov    0x2e75(%rip),%rax
pop    %rbp
ret

x86 assembly (clang, -O2):
<icspio_err>:
cmp    $0x5,%edi
ja     1117 <icspio_err+0x17>
movslq %edi,%rax
lea    0xf3d(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
ret
lea    0xf20(%rip),%rax
ret

LLVM IR (-O0):
@icspio_err.errmsg = internal global i8* null
@.str = [8 x i8] c"ERRNONE\00"
@.str.1 = [11 x i8] c"ERRTIMEOUT\00"
@.str.2 = [12 x i8] c"ERRPROTOCOL\00"
@.str.3 = [10 x i8] c"ERRPARITY\00"
@.str.4 = [10 x i8] c"ERRNOTSUP\00"
@.str.5 = [11 x i8] c"ERRINVALID\00"
@.str.6 = [11 x i8] c"ERRUNKNOWN\00"
define i8* @icspio_err(i32 %0) {
%2 = alloca i32
store i32 %0, i32* %2
%3 = load i32, i32* %2
switch i32 %3, label %10 [
i32 0, label %4
i32 1, label %5
i32 2, label %6
i32 3, label %7
i32 4, label %8
i32 5, label %9
]
4: ; preds = %1
store i8* getelementptr inbounds ([8 x i8], [8 x i8]* @.str, i64 0, i64 0), i8** @icspio_err.errmsg
br label %11
5: ; preds = %1
store i8* getelementptr inbounds ([11 x i8], [11 x i8]* @.str.1, i64 0, i64 0), i8** @icspio_err.errmsg
br label %11
6: ; preds = %1
store i8* getelementptr inbounds ([12 x i8], [12 x i8]* @.str.2, i64 0, i64 0), i8** @icspio_err.errmsg
br label %11
7: ; preds = %1
store i8* getelementptr inbounds ([10 x i8], [10 x i8]* @.str.3, i64 0, i64 0), i8** @icspio_err.errmsg
br label %11
8: ; preds = %1
store i8* getelementptr inbounds ([10 x i8], [10 x i8]* @.str.4, i64 0, i64 0), i8** @icspio_err.errmsg
br label %11
9: ; preds = %1
store i8* getelementptr inbounds ([11 x i8], [11 x i8]* @.str.5, i64 0, i64 0), i8** @icspio_err.errmsg
br label %11
10: ; preds = %1
store i8* getelementptr inbounds ([11 x i8], [11 x i8]* @.str.6, i64 0, i64 0), i8** @icspio_err.errmsg
br label %11
11: ; preds = %10, %9, %8, %7, %6, %5, %4
%12 = load i8*, i8** @icspio_err.errmsg
ret i8* %12
}

LLVM IR (-O2):
@.str = [8 x i8] c"ERRNONE\00"
@.str.1 = [11 x i8] c"ERRTIMEOUT\00"
@.str.2 = [12 x i8] c"ERRPROTOCOL\00"
@.str.3 = [10 x i8] c"ERRPARITY\00"
@.str.4 = [10 x i8] c"ERRNOTSUP\00"
@.str.5 = [11 x i8] c"ERRINVALID\00"
@.str.6 = [11 x i8] c"ERRUNKNOWN\00"
@reltable.icspio_err = [6 x i32] [i32 trunc (i64 sub (i64 ptrtoint ([8 x i8]* @.str to i64), i64 ptrtoint ([6 x i32]* @reltable.icspio_err to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([11 x i8]* @.str.1 to i64), i64 ptrtoint ([6 x i32]* @reltable.icspio_err to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([12 x i8]* @.str.2 to i64), i64 ptrtoint ([6 x i32]* @reltable.icspio_err to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([10 x i8]* @.str.3 to i64), i64 ptrtoint ([6 x i32]* @reltable.icspio_err to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([10 x i8]* @.str.4 to i64), i64 ptrtoint ([6 x i32]* @reltable.icspio_err to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([11 x i8]* @.str.5 to i64), i64 ptrtoint ([6 x i32]* @reltable.icspio_err to i64)) to i32)]
define i8* @icspio_err(i32 %0) {
%2 = icmp ult i32 %0, 6
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 ([6 x i32]* @reltable.icspio_err 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
}