#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*/ printf(char *, ...);
int /*<<< orphan*/ scanf(char *, int *);
int main(void) {
  int sum = 0, n = 0, i = 0;
  printf("n的值: ");
  scanf("%d", &n);
  for (i = n; i > 0; i--) {
    sum += i;
  }
  printf("1到%d的和为: %d\n", n, sum);
  return 0;
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x10,%rsp
movl   $0x0,-0x4(%rbp)
movl   $0x0,-0x8(%rbp)
movl   $0x0,-0xc(%rbp)
movl   $0x0,-0x10(%rbp)
lea    0xeb5(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
lea    0xeb1(%rip),%rdi
lea    -0xc(%rbp),%rsi
call   1040 <scanf@plt>
mov    -0xc(%rbp),%eax
mov    %eax,-0x10(%rbp)
cmpl   $0x0,-0x10(%rbp)
jle    1189 <main+0x69>
mov    -0x10(%rbp),%eax
add    -0x8(%rbp),%eax
mov    %eax,-0x8(%rbp)
mov    -0x10(%rbp),%eax
add    $0xffffffff,%eax
mov    %eax,-0x10(%rbp)
jmp    1168 <main+0x48>
mov    -0xc(%rbp),%esi
mov    -0x8(%rbp),%edx
lea    0xe77(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
xor    %eax,%eax
add    $0x10,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %rbx
sub    $0x10,%rsp
movl   $0x0,0xc(%rsp)
lea    0xecc(%rip),%rdi
xor    %ebx,%ebx
xor    %eax,%eax
call   1030 <printf@plt>
lea    0xec6(%rip),%rdi
lea    0xc(%rsp),%rsi
call   1040 <scanf@plt>
mov    0xc(%rsp),%esi
test   %esi,%esi
jle    116c <main+0x4c>
lea    -0x1(%rsi),%eax
lea    -0x2(%rsi),%ecx
imul   %rax,%rcx
mov    %eax,%ebx
imul   %eax,%ebx
shr    %rcx
add    %esi,%ebx
sub    %ecx,%ebx
lea    0xe9a(%rip),%rdi
mov    %ebx,%edx
xor    %eax,%eax
call   1030 <printf@plt>
xor    %eax,%eax
add    $0x10,%rsp
pop    %rbx
ret

LLVM IR (-O0):
@.str = [10 x i8] c"n\E7\9A\84\E5\80\BC: \00"
@.str.1 = [3 x i8] c"%d\00"
@.str.2 = [21 x i8] c"1\E5\88\B0%d\E7\9A\84\E5\92\8C\E4\B8\BA: %d\0A\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* %2
store i32 0, i32* %3
store i32 0, i32* %4
%5 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([10 x i8], [10 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* %3)
%7 = load i32, i32* %3
store i32 %7, i32* %4
br label %8
8: ; preds = %15, %0
%9 = load i32, i32* %4
%10 = icmp sgt i32 %9, 0
br i1 %10, label %11, label %18
11: ; preds = %8
%12 = load i32, i32* %4
%13 = load i32, i32* %2
%14 = add nsw i32 %13, %12
store i32 %14, i32* %2
br label %15
15: ; preds = %11
%16 = load i32, i32* %4
%17 = add nsw i32 %16, -1
store i32 %17, i32* %4
br label %8
18: ; preds = %8
%19 = load i32, i32* %3
%20 = load i32, i32* %2
%21 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([21 x i8], [21 x i8]* @.str.2, i64 0, i64 0), i32 %19, i32 %20)
ret i32 0
}

LLVM IR (-O2):
@.str = [10 x i8] c"n\E7\9A\84\E5\80\BC: \00"
@.str.1 = [3 x i8] c"%d\00"
@.str.2 = [21 x i8] c"1\E5\88\B0%d\E7\9A\84\E5\92\8C\E4\B8\BA: %d\0A\00"
define i32 @main() {
%1 = alloca i32
%2 = bitcast i32* %1 to i8*
store i32 0, i32* %1
%3 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([10 x i8], [10 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 sgt i32 %5, 0
br i1 %6, label %7, label %18
7: ; preds = %0
%8 = add nsw i32 %5, -1
%9 = mul i32 %8, %8
%10 = zext i32 %8 to i33
%11 = add nsw i32 %5, -2
%12 = zext i32 %11 to i33
%13 = mul i33 %10, %12
%14 = lshr i33 %13, 1
%15 = trunc i33 %14 to i32
%16 = add i32 %5, %9
%17 = sub i32 %16, %15
br label %18
18: ; preds = %7, %0
%19 = phi i32 [ 0, %0 ], [ %17, %7 ]
%20 = call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([21 x i8], [21 x i8]* @.str.2, i64 0, i64 0), i32 %5, i32 %19)
ret i32 0
}