char *jst_to_str(int jst) {
  if (jst == 0)
    return "default";
  if (jst == 1)
    return "left";
  if (jst == 2)
    return "right";
  if (jst == 3)
    return "center";
  return "unknown";
}


x86 assembly (clang, -O0):
<jst_to_str>:
push   %rbp
mov    %rsp,%rbp
mov    %edi,-0xc(%rbp)
cmpl   $0x0,-0xc(%rbp)
jne    1121 <jst_to_str+0x21>
lea    0xee8(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    117a <jst_to_str+0x7a>
cmpl   $0x1,-0xc(%rbp)
jne    113b <jst_to_str+0x3b>
lea    0xed6(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    117a <jst_to_str+0x7a>
cmpl   $0x2,-0xc(%rbp)
jne    1155 <jst_to_str+0x55>
lea    0xec1(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    117a <jst_to_str+0x7a>
cmpl   $0x3,-0xc(%rbp)
jne    116f <jst_to_str+0x6f>
lea    0xead(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    117a <jst_to_str+0x7a>
lea    0xea4(%rip),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
pop    %rbp
ret

x86 assembly (clang, -O2):
<jst_to_str>:
cmp    $0x3,%edi
ja     1117 <jst_to_str+0x17>
movslq %edi,%rax
lea    0xf15(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
ret
lea    0xefc(%rip),%rax
ret

LLVM IR (-O0):
@.str = [8 x i8] c"default\00"
@.str.1 = [5 x i8] c"left\00"
@.str.2 = [6 x i8] c"right\00"
@.str.3 = [7 x i8] c"center\00"
@.str.4 = [8 x i8] c"unknown\00"
define i8* @jst_to_str(i32 %0) {
%2 = alloca i8*
%3 = alloca i32
store i32 %0, i32* %3
%4 = load i32, i32* %3
%5 = icmp eq i32 %4, 0
br i1 %5, label %6, label %7
6: ; preds = %1
store i8* getelementptr inbounds ([8 x i8], [8 x i8]* @.str, i64 0, i64 0), i8** %2
br label %20
7: ; preds = %1
%8 = load i32, i32* %3
%9 = icmp eq i32 %8, 1
br i1 %9, label %10, label %11
10: ; preds = %7
store i8* getelementptr inbounds ([5 x i8], [5 x i8]* @.str.1, i64 0, i64 0), i8** %2
br label %20
11: ; preds = %7
%12 = load i32, i32* %3
%13 = icmp eq i32 %12, 2
br i1 %13, label %14, label %15
14: ; preds = %11
store i8* getelementptr inbounds ([6 x i8], [6 x i8]* @.str.2, i64 0, i64 0), i8** %2
br label %20
15: ; preds = %11
%16 = load i32, i32* %3
%17 = icmp eq i32 %16, 3
br i1 %17, label %18, label %19
18: ; preds = %15
store i8* getelementptr inbounds ([7 x i8], [7 x i8]* @.str.3, i64 0, i64 0), i8** %2
br label %20
19: ; preds = %15
store i8* getelementptr inbounds ([8 x i8], [8 x i8]* @.str.4, i64 0, i64 0), i8** %2
br label %20
20: ; preds = %19, %18, %14, %10, %6
%21 = load i8*, i8** %2
ret i8* %21
}

LLVM IR (-O2):
@.str = [8 x i8] c"default\00"
@.str.1 = [5 x i8] c"left\00"
@.str.2 = [6 x i8] c"right\00"
@.str.3 = [7 x i8] c"center\00"
@.str.4 = [8 x i8] c"unknown\00"
@reltable.jst_to_str = [4 x i32] [i32 trunc (i64 sub (i64 ptrtoint ([8 x i8]* @.str to i64), i64 ptrtoint ([4 x i32]* @reltable.jst_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([5 x i8]* @.str.1 to i64), i64 ptrtoint ([4 x i32]* @reltable.jst_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([6 x i8]* @.str.2 to i64), i64 ptrtoint ([4 x i32]* @reltable.jst_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([7 x i8]* @.str.3 to i64), i64 ptrtoint ([4 x i32]* @reltable.jst_to_str to i64)) to i32)]
define i8* @jst_to_str(i32 %0) {
%2 = icmp ult i32 %0, 4
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 ([4 x i32]* @reltable.jst_to_str to i8*), i64 %5)
br label %7
7: ; preds = %1, %3
%8 = phi i8* [ %6, %3 ], [ getelementptr inbounds ([8 x i8], [8 x i8]* @.str.4, i64 0, i64 0), %1 ]
ret i8* %8
}