#define NULL ((void *)0)
typedef unsigned long size_t; // Customize by platform.
typedef long intptr_t;
typedef unsigned long uintptr_t;
typedef long scalar_t__; // Either arithmetic or pointer type.
/* By default, we understand bool (as a convenience). */
typedef int bool;
#define false 0
#define true 1

/* Forward declarations */

/* Type definitions */

/* Variables and functions */
int /*<<< orphan*/ getch();
int /*<<< orphan*/ printf(char *, ...);
int /*<<< orphan*/ scanf(char *, int *);
int main() {
  int n, digit, sum = 0;
  printf("Enter a number: ");
  scanf("%d", &n);
  while (n) {
    digit = n % 10;
    n /= 10;
    sum += digit;
  }
  printf("Sum of digits: %d", sum);
  getch();
  return 0;
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x10,%rsp
movl   $0x0,-0x4(%rbp)
movl   $0x0,-0x10(%rbp)
lea    0xeb3(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
lea    0xec5(%rip),%rdi
lea    -0x8(%rbp),%rsi
call   1040 <scanf@plt>
cmpl   $0x0,-0x8(%rbp)
je     1198 <main+0x68>
mov    -0x8(%rbp),%eax
mov    $0xa,%ecx
cltd
idiv   %ecx
mov    %edx,-0xc(%rbp)
mov    -0x8(%rbp),%eax
mov    $0xa,%ecx
cltd
idiv   %ecx
mov    %eax,-0x8(%rbp)
mov    -0xc(%rbp),%eax
add    -0x10(%rbp),%eax
mov    %eax,-0x10(%rbp)
jmp    1164 <main+0x34>
mov    -0x10(%rbp),%esi
lea    0xe6f(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
mov    $0x0,%al
call   1050 <getch@plt>
xor    %eax,%eax
add    $0x10,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %rbx
sub    $0x10,%rsp
lea    0xec4(%rip),%rdi
xor    %ebx,%ebx
xor    %eax,%eax
call   1030 <printf@plt>
lea    0xed4(%rip),%rdi
lea    0xc(%rsp),%rsi
call   1040 <scanf@plt>
mov    0xc(%rsp),%eax
test   %eax,%eax
je     118f <main+0x5f>
xor    %ebx,%ebx
movslq %eax,%rcx
imul   $0x66666667,%rcx,%rax
mov    %rax,%rdx
shr    $0x3f,%rdx
sar    $0x22,%rax
add    %edx,%eax
lea    (%rax,%rax,1),%edx
lea    (%rdx,%rdx,4),%edx
mov    %ecx,%esi
sub    %edx,%esi
add    %esi,%ebx
add    $0x9,%ecx
cmp    $0x12,%ecx
ja     1160 <main+0x30>
mov    %eax,0xc(%rsp)
lea    0xe7b(%rip),%rdi
mov    %ebx,%esi
xor    %eax,%eax
call   1030 <printf@plt>
xor    %eax,%eax
call   1050 <getch@plt>
xor    %eax,%eax
add    $0x10,%rsp
pop    %rbx
ret

LLVM IR (-O0):
@.str = [17 x i8] c"Enter a number: \00"
@.str.1 = [3 x i8] c"%d\00"
@.str.2 = [18 x i8] c"Sum of digits: %d\00"
define i32 @main() {
%1 = alloca i32
%2 = alloca i32
%3 = alloca i32
%4 = alloca i32
store i32 0, i32* %1
store i32 0, i32* %4
%5 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([17 x i8], [17 x i8]* @.str, i64 0, i64 0))
%6 = call i32 @scanf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0), i32* %2)
br label %7
7: ; preds = %10, %0
%8 = load i32, i32* %2
%9 = icmp ne i32 %8, 0
br i1 %9, label %10, label %18
10: ; preds = %7
%11 = load i32, i32* %2
%12 = srem i32 %11, 10
store i32 %12, i32* %3
%13 = load i32, i32* %2
%14 = sdiv i32 %13, 10
store i32 %14, i32* %2
%15 = load i32, i32* %3
%16 = load i32, i32* %4
%17 = add nsw i32 %16, %15
store i32 %17, i32* %4
br label %7
18: ; preds = %7
%19 = load i32, i32* %4
%20 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([18 x i8], [18 x i8]* @.str.2, i64 0, i64 0), i32 %19)
%21 = call i32 (...) @getch()
ret i32 0
}

LLVM IR (-O2):
@.str = [17 x i8] c"Enter a number: \00"
@.str.1 = [3 x i8] c"%d\00"
@.str.2 = [18 x i8] c"Sum of digits: %d\00"
define i32 @main() {
%1 = alloca i32
%2 = bitcast i32* %1 to i8*
%3 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([17 x i8], [17 x i8]* @.str, i64 0, i64 0))
%4 = call i32 @scanf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0), i32* %1)
%5 = load i32, i32* %1
%6 = icmp eq i32 %5, 0
br i1 %6, label %16, label %7
7: ; preds = %0, %7
%8 = phi i32 [ %12, %7 ], [ 0, %0 ]
%9 = phi i32 [ %11, %7 ], [ %5, %0 ]
%10 = srem i32 %9, 10
%11 = sdiv i32 %9, 10
%12 = add nsw i32 %8, %10
%13 = add i32 %9, 9
%14 = icmp ult i32 %13, 19
br i1 %14, label %15, label %7
15: ; preds = %7
store i32 %11, i32* %1
br label %16
16: ; preds = %15, %0
%17 = phi i32 [ %12, %15 ], [ 0, %0 ]
%18 = call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([18 x i8], [18 x i8]* @.str.2, i64 0, i64 0), i32 %17)
%19 = call i32 (...) @getch()
ret i32 0
}