int main(int argc, char const *argv[]) {
  long num;
  long sum = 0L;
  _Bool input_is_good;
  printf("Please enter an integer to be summed. ");
  printf("(q to quit): ");
  input_is_good = (scanf("%ld", &num) == 1);
  while (input_is_good) {
    sum = sum + num;
    printf("Please enter next integer (q to quit): ");
    input_is_good = (scanf("%ld", &num) == 1);
  }
  printf("Those integers sum to %ld.\n", sum);
  return 0;
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x30,%rsp
movl   $0x0,-0x4(%rbp)
mov    %edi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
movq   $0x0,-0x20(%rbp)
lea    0xebb(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
lea    0xef2(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
lea    0xec6(%rip),%rdi
lea    -0x18(%rbp),%rsi
mov    $0x0,%al
call   1040 <scanf@plt>
cmp    $0x1,%eax
sete   %al
and    $0x1,%al
mov    %al,-0x21(%rbp)
testb  $0x1,-0x21(%rbp)
je     11bd <main+0x9d>
mov    -0x20(%rbp),%rax
add    -0x18(%rbp),%rax
mov    %rax,-0x20(%rbp)
lea    0xe97(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
lea    0xe85(%rip),%rdi
lea    -0x18(%rbp),%rsi
mov    $0x0,%al
call   1040 <scanf@plt>
cmp    $0x1,%eax
sete   %al
and    $0x1,%al
mov    %al,-0x21(%rbp)
jmp    1177 <main+0x57>
mov    -0x20(%rbp),%rsi
lea    0xe8b(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
xor    %eax,%eax
add    $0x30,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %r15
push   %r14
push   %r12
push   %rbx
push   %rax
lea    0xed1(%rip),%rdi
xor    %ebx,%ebx
xor    %eax,%eax
call   1030 <printf@plt>
lea    0xf06(%rip),%rdi
xor    %eax,%eax
call   1030 <printf@plt>
lea    0xeda(%rip),%rdi
mov    %rsp,%rsi
xor    %eax,%eax
call   1040 <scanf@plt>
cmp    $0x1,%eax
jne    1190 <main+0x70>
lea    0xec8(%rip),%r14
lea    0xebd(%rip),%r15
mov    %rsp,%r12
xor    %ebx,%ebx
nop
add    (%rsp),%rbx
mov    %r14,%rdi
xor    %eax,%eax
call   1030 <printf@plt>
mov    %r15,%rdi
mov    %r12,%rsi
xor    %eax,%eax
call   1040 <scanf@plt>
cmp    $0x1,%eax
je     1170 <main+0x50>
lea    0xebc(%rip),%rdi
mov    %rbx,%rsi
xor    %eax,%eax
call   1030 <printf@plt>
xor    %eax,%eax
add    $0x8,%rsp
pop    %rbx
pop    %r12
pop    %r14
pop    %r15
ret

LLVM IR (-O0):
@.str = [39 x i8] c"Please enter an integer to be summed. \00"
@.str.1 = [14 x i8] c"(q to quit): \00"
@.str.2 = [4 x i8] c"%ld\00"
@.str.3 = [40 x i8] c"Please enter next integer (q to quit): \00"
@.str.4 = [28 x i8] c"Those integers sum to %ld.\0A\00"
define i32 @main(i32 %0, i8** %1) {
%3 = alloca i32
%4 = alloca i32
%5 = alloca i8**
%6 = alloca i64
%7 = alloca i64
%8 = alloca i8
store i32 0, i32* %3
store i32 %0, i32* %4
store i8** %1, i8*** %5
store i64 0, i64* %7
%9 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([39 x i8], [39 x i8]* @.str, i64 0, i64 0))
%10 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([14 x i8], [14 x i8]* @.str.1, i64 0, i64 0))
%11 = call i32 (i8*, ...) @scanf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.2, i64 0, i64 0), i64* %6)
%12 = icmp eq i32 %11, 1
%13 = zext i1 %12 to i8
store i8 %13, i8* %8
br label %14
14: ; preds = %17, %2
%15 = load i8, i8* %8
%16 = trunc i8 %15 to i1
br i1 %16, label %17, label %25
17: ; preds = %14
%18 = load i64, i64* %7
%19 = load i64, i64* %6
%20 = add nsw i64 %18, %19
store i64 %20, i64* %7
%21 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([40 x i8], [40 x i8]* @.str.3, i64 0, i64 0))
%22 = call i32 (i8*, ...) @scanf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.2, i64 0, i64 0), i64* %6)
%23 = icmp eq i32 %22, 1
%24 = zext i1 %23 to i8
store i8 %24, i8* %8
br label %14
25: ; preds = %14
%26 = load i64, i64* %7
%27 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([28 x i8], [28 x i8]* @.str.4, i64 0, i64 0), i64 %26)
ret i32 0
}

LLVM IR (-O2):
@.str = [39 x i8] c"Please enter an integer to be summed. \00"
@.str.1 = [14 x i8] c"(q to quit): \00"
@.str.2 = [4 x i8] c"%ld\00"
@.str.3 = [40 x i8] c"Please enter next integer (q to quit): \00"
@.str.4 = [28 x i8] c"Those integers sum to %ld.\0A\00"
define i32 @main(i32 %0, i8** nocapture readnone %1) {
%3 = alloca i64
%4 = bitcast i64* %3 to i8*
%5 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([39 x i8], [39 x i8]* @.str, i64 0, i64 0))
%6 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([14 x i8], [14 x i8]* @.str.1, i64 0, i64 0))
%7 = call i32 (i8*, ...) @scanf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.2, i64 0, i64 0), i64* %3)
%8 = icmp eq i32 %7, 1
br i1 %8, label %9, label %16
9: ; preds = %2, %9
%10 = phi i64 [ %12, %9 ], [ 0, %2 ]
%11 = load i64, i64* %3
%12 = add nsw i64 %11, %10
%13 = call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([40 x i8], [40 x i8]* @.str.3, i64 0, i64 0))
%14 = call i32 (i8*, ...) @scanf(i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.2, i64 0, i64 0), i64* %3)
%15 = icmp eq i32 %14, 1
br i1 %15, label %9, label %16
16: ; preds = %9, %2
%17 = phi i64 [ 0, %2 ], [ %12, %9 ]
%18 = call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([28 x i8], [28 x i8]* @.str.4, i64 0, i64 0), i64 %17)
ret i32 0
}