const char *cspr_mode_to_str(unsigned int _CSPR) {
  switch (_CSPR & 0x1f) {
  case 0x10:
    return "USR";
  case 0x1F:
    return "SYS";
  case 0x13:
    return "SVC";
  case 0x17:
    return "ABT";
  case 0x11:
    return "FIQ";
  case 0x12:
    return "IRQ";
  case 0x18:
    return "UND";
  default:
    return "???";
  }
}


x86 assembly (clang, -O0):
<cspr_mode_to_str>:
push   %rbp
mov    %rsp,%rbp
mov    %edi,-0xc(%rbp)
mov    -0xc(%rbp),%eax
and    $0x1f,%eax
add    $0xfffffff0,%eax
mov    %eax,%ecx
mov    %rcx,-0x18(%rbp)
sub    $0xf,%eax
ja     11a3 <cspr_mode_to_str+0xa3>
mov    -0x18(%rbp),%rax
lea    0xed6(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
jmp    *%rax
lea    0xf06(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11ae <cspr_mode_to_str+0xae>
lea    0xefa(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11ae <cspr_mode_to_str+0xae>
lea    0xeee(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11ae <cspr_mode_to_str+0xae>
lea    0xee2(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11ae <cspr_mode_to_str+0xae>
lea    0xed6(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11ae <cspr_mode_to_str+0xae>
lea    0xeca(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11ae <cspr_mode_to_str+0xae>
lea    0xebe(%rip),%rax
mov    %rax,-0x8(%rbp)
jmp    11ae <cspr_mode_to_str+0xae>
lea    0xeb2(%rip),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
pop    %rbp
ret

x86 assembly (clang, -O2):
<cspr_mode_to_str>:
and    $0x1f,%edi
add    $0xfffffff0,%edi
cmp    $0xf,%edi
ja     111d <cspr_mode_to_str+0x1d>
movslq %edi,%rax
lea    0xf0b(%rip),%rcx
movslq (%rcx,%rax,4),%rax
add    %rcx,%rax
ret
lea    0xef8(%rip),%rax
ret

LLVM IR (-O0):
@.str = [4 x i8] c"USR\00"
@.str.1 = [4 x i8] c"SYS\00"
@.str.2 = [4 x i8] c"SVC\00"
@.str.3 = [4 x i8] c"ABT\00"
@.str.4 = [4 x i8] c"FIQ\00"
@.str.5 = [4 x i8] c"IRQ\00"
@.str.6 = [4 x i8] c"UND\00"
@.str.7 = [4 x i8] c"???\00"
define i8* @cspr_mode_to_str(i32 %0) {
%2 = alloca i8*
%3 = alloca i32
store i32 %0, i32* %3
%4 = load i32, i32* %3
%5 = and i32 %4, 31
switch i32 %5, label %13 [
i32 16, label %6
i32 31, label %7
i32 19, label %8
i32 23, label %9
i32 17, label %10
i32 18, label %11
i32 24, label %12
]
6: ; preds = %1
store i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i64 0, i64 0), i8** %2
br label %14
7: ; preds = %1
store i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.1, i64 0, i64 0), i8** %2
br label %14
8: ; preds = %1
store i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.2, i64 0, i64 0), i8** %2
br label %14
9: ; preds = %1
store i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.3, i64 0, i64 0), i8** %2
br label %14
10: ; preds = %1
store i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.4, i64 0, i64 0), i8** %2
br label %14
11: ; preds = %1
store i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.5, i64 0, i64 0), i8** %2
br label %14
12: ; preds = %1
store i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.6, i64 0, i64 0), i8** %2
br label %14
13: ; preds = %1
store i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.7, i64 0, i64 0), i8** %2
br label %14
14: ; preds = %13, %12, %11, %10, %9, %8, %7, %6
%15 = load i8*, i8** %2
ret i8* %15
}

LLVM IR (-O2):
@.str = [4 x i8] c"USR\00"
@.str.1 = [4 x i8] c"SYS\00"
@.str.2 = [4 x i8] c"SVC\00"
@.str.3 = [4 x i8] c"ABT\00"
@.str.4 = [4 x i8] c"FIQ\00"
@.str.5 = [4 x i8] c"IRQ\00"
@.str.6 = [4 x i8] c"UND\00"
@.str.7 = [4 x i8] c"???\00"
@reltable.cspr_mode_to_str = [16 x i32] [i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.4 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.5 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.2 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.7 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.7 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.7 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.3 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.6 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.7 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.7 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.7 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.7 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.7 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.7 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32), i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.1 to i64), i64 ptrtoint ([16 x i32]* @reltable.cspr_mode_to_str to i64)) to i32)]
define i8* @cspr_mode_to_str(i32 %0) {
%2 = and i32 %0, 31
%3 = add nsw i32 %2, -16
%4 = icmp ult i32 %3, 16
br i1 %4, label %5, label %9
5: ; preds = %1
%6 = sext i32 %3 to i64
%7 = shl i64 %6, 2
%8 = call i8* @llvm.load.relative.i64(i8* bitcast ([16 x i32]* @reltable.cspr_mode_to_str to i8*), i64 %7)
br label %9
9: ; preds = %1, %5
%10 = phi i8* [ %8, %5 ], [ getelementptr inbounds ([4 x i8], [4 x i8]* @.str.7, i64 0, i64 0), %1 ]
ret i8* %10
}