char *PICC_get_err_message(int errcode) {
  switch (errcode) {
  case 0:
    return "memory allocation";
  case 1:
    return "pthread creation";
  case 2:
    return "a deadlock occured";
  default:
    return "unknwon error";
  }
}


x86 assembly (clang, -O0):
<PICC_get_err_message>:
push   %rbp
mov    %rsp,%rbp
mov    %edi,-0xc(%rbp)
mov    -0xc(%rbp),%eax
mov    %eax,-0x10(%rbp)
test   %eax,%eax
je     113c <PICC_get_err_message+0x3c>
jmp    111a <PICC_get_err_message+0x1a>
mov    -0x10(%rbp),%eax
sub    $0x1,%eax
je     114c <PICC_get_err_message+0x4c>
jmp    112b <PICC_get_err_message+0x2b>
mov    -0x10(%rbp),%eax
sub    $0x2,%eax
je     115c <PICC_get_err_message+0x5c>
jmp    116c <PICC_get_err_message+0x6c>
lea    0xebd(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    1177 <PICC_get_err_message+0x77>
lea    0xebf(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    1177 <PICC_get_err_message+0x77>
lea    0xec0(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    1177 <PICC_get_err_message+0x77>
lea    0xec3(%rip),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
pop    %rbp
ret

x86 assembly (clang, -O2):
<PICC_get_err_message>:
cmp    $0x2,%edi
ja     1117 <PICC_get_err_message+0x17>
movslq %edi,%rax
lea    0xf35(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
ret
lea    0xf18(%rip),%rax
ret

LLVM IR (-O0):
@.str = [18 x i8] c"memory allocation\00"
@.str.1 = [17 x i8] c"pthread creation\00"
@.str.2 = [19 x i8] c"a deadlock occured\00"
@.str.3 = [14 x i8] c"unknwon error\00"
define i8* @PICC_get_err_message(i32 %0) {
%2 = alloca i8*
%3 = alloca i32
store i32 %0, i32* %3
%4 = load i32, i32* %3
switch i32 %4, label %8 [
i32 0, label %5
i32 1, label %6
i32 2, label %7
]
5: ; preds = %1
store i8* getelementptr inbounds ([18 x i8], [18 x i8]* @.str, i64 0, i64 0), i8** %2
br label %9
6: ; preds = %1
store i8* getelementptr inbounds ([17 x i8], [17 x i8]* @.str.1, i64 0, i64 0), i8** %2
br label %9
7: ; preds = %1
store i8* getelementptr inbounds ([19 x i8], [19 x i8]* @.str.2, i64 0, i64 0), i8** %2
br label %9
8: ; preds = %1
store i8* getelementptr inbounds ([14 x i8], [14 x i8]* @.str.3, i64 0, i64 0), i8** %2
br label %9
9: ; preds = %8, %7, %6, %5
%10 = load i8*, i8** %2
ret i8* %10
}

LLVM IR (-O2):
@.str = [18 x i8] c"memory allocation\00"
@.str.1 = [17 x i8] c"pthread creation\00"
@.str.2 = [19 x i8] c"a deadlock occured\00"
@.str.3 = [14 x i8] c"unknwon error\00"
@reltable.PICC_get_err_message = [3 x i32] [i32 trunc (i64 sub (i64 ptrtoint ([18 x i8]* @.str to i64), i64 ptrtoint ([3 x i32]* @reltable.PICC_get_err_message to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([17 x i8]* @.str.1 to i64), i64 ptrtoint ([3 x i32]* @reltable.PICC_get_err_message to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([19 x i8]* @.str.2 to i64), i64 ptrtoint ([3 x i32]* @reltable.PICC_get_err_message to i64)) to i32)]
define i8* @PICC_get_err_message(i32 %0) {
%2 = icmp ult i32 %0, 3
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 ([3 x i32]* @reltable.PICC_get_err_message to i8*), i64 %5)
br label %7
7: ; preds = %1, %3
%8 = phi i8* [ %6, %3 ], [ getelementptr inbounds ([14 x i8], [14 x i8]* @.str.3, i64 0, i64 0), %1 ]
ret i8* %8
}