#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 *, char);
int /*<<< orphan*/ scanf(char *, char *);
int strlen(char *);
int main() {
  char str[1024];
  scanf("%1024s", str);
  int n = strlen(str);
  for (n = n - 1; n >= 0; n--)
    printf("%c", str[n]);
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x420,%rsp
movl   $0x0,-0x4(%rbp)
lea    -0x410(%rbp),%rsi
lea    0xeb0(%rip),%rdi
call   1050 <scanf@plt>
lea    -0x410(%rbp),%rdi
call   1030 <strlen@plt>
mov    %eax,-0x414(%rbp)
mov    -0x414(%rbp),%eax
sub    $0x1,%eax
mov    %eax,-0x414(%rbp)
cmpl   $0x0,-0x414(%rbp)
jl     11b2 <main+0x82>
movslq -0x414(%rbp),%rax
lea    0xe76(%rip),%rdi
movsbl -0x410(%rbp,%rax,1),%esi
ff
call   1040 <printf@plt>
mov    -0x414(%rbp),%eax
add    $0xffffffff,%eax
mov    %eax,-0x414(%rbp)
jmp    1176 <main+0x46>
mov    -0x4(%rbp),%eax
add    $0x420,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %r14
push   %rbx
sub    $0x408,%rsp
lea    0xebf(%rip),%rdi
mov    %rsp,%rbx
mov    %rbx,%rsi
call   1050 <scanf@plt>
mov    %rbx,%rdi
call   1030 <strlen@plt>
test   %eax,%eax
jle    1189 <main+0x59>
mov    %eax,%ebx
add    $0x1,%rbx
lea    0xea2(%rip),%r14
cs nopw 0x0(%rax,%rax,1)
nop
lea    -0x2(%rbx),%eax
movsbl (%rsp,%rax,1),%esi
mov    %r14,%rdi
call   1040 <printf@plt>
add    $0xffffffffffffffff,%rbx
cmp    $0x1,%rbx
ja     1170 <main+0x40>
xor    %eax,%eax
add    $0x408,%rsp
pop    %rbx
pop    %r14
ret

LLVM IR (-O0):
@.str = [7 x i8] c"%1024s\00"
@.str.1 = [3 x i8] c"%c\00"
define i32 @main() {
%1 = alloca i32
%2 = alloca [1024 x i8]
%3 = alloca i32
store i32 0, i32* %1
%4 = getelementptr inbounds [1024 x i8], [1024 x i8]* %2, i64 0, i64 0
%5 = call i32 @scanf(i8* getelementptr inbounds ([7 x i8], [7 x i8]* @.str, i64 0, i64 0), i8* %4)
%6 = getelementptr inbounds [1024 x i8], [1024 x i8]* %2, i64 0, i64 0
%7 = call i32 @strlen(i8* %6)
store i32 %7, i32* %3
%8 = load i32, i32* %3
%9 = sub nsw i32 %8, 1
store i32 %9, i32* %3
br label %10
10: ; preds = %19, %0
%11 = load i32, i32* %3
%12 = icmp sge i32 %11, 0
br i1 %12, label %13, label %22
13: ; preds = %10
%14 = load i32, i32* %3
%15 = sext i32 %14 to i64
%16 = getelementptr inbounds [1024 x i8], [1024 x i8]* %2, i64 0, i64 %15
%17 = load i8, i8* %16
%18 = call i32 @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0), i8 signext %17)
br label %19
19: ; preds = %13
%20 = load i32, i32* %3
%21 = add nsw i32 %20, -1
store i32 %21, i32* %3
br label %10
22: ; preds = %10
%23 = load i32, i32* %1
ret i32 %23
}

LLVM IR (-O2):
@.str = [7 x i8] c"%1024s\00"
@.str.1 = [3 x i8] c"%c\00"
define i32 @main() {
%1 = alloca [1024 x i8]
%2 = getelementptr inbounds [1024 x i8], [1024 x i8]* %1, i64 0, i64 0
%3 = call i32 @scanf(i8* getelementptr inbounds ([7 x i8], [7 x i8]* @.str, i64 0, i64 0), i8* %2)
%4 = call i32 @strlen(i8* %2)
%5 = icmp sgt i32 %4, 0
br i1 %5, label %6, label %16
6: ; preds = %0
%7 = zext i32 %4 to i64
br label %8
8: ; preds = %6, %8
%9 = phi i64 [ %7, %6 ], [ %10, %8 ]
%10 = add nsw i64 %9, -1
%11 = and i64 %10, 4294967295
%12 = getelementptr inbounds [1024 x i8], [1024 x i8]* %1, i64 0, i64 %11
%13 = load i8, i8* %12
%14 = call i32 @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0), i8 signext %13)
%15 = icmp ugt i64 %9, 1
br i1 %15, label %8, label %16
16: ; preds = %8, %0
ret i32 0
}