#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 *, char **);
int main() {
  void merge(char string1[], char string2[], char string[]);
  char s1[20], s2[40], s[20];
  printf("input string1:");
  scanf("%s", &s1);
  printf("input string2:");
  scanf("%s", &s2);
  merge(s1, s2, s);
  printf("new string is %s\n", s);
  return 0;
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x70,%rsp
movl   $0x0,-0x4(%rbp)
lea    0xeba(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
lea    -0x20(%rbp),%rsi
lea    0xeb7(%rip),%rdi
call   1050 <scanf@plt>
lea    0xeae(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
lea    -0x50(%rbp),%rsi
lea    0xe99(%rip),%rdi
call   1050 <scanf@plt>
lea    -0x20(%rbp),%rdi
lea    -0x50(%rbp),%rsi
lea    -0x70(%rbp),%rdx
call   1040 <merge@plt>
lea    -0x70(%rbp),%rsi
lea    0xe8a(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
xor    %eax,%eax
add    $0x70,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %r15
push   %r14
push   %rbx
sub    $0x70,%rsp
lea    0xec0(%rip),%rdi
xor    %eax,%eax
call   1030 <printf@plt>
lea    0xec1(%rip),%r15
lea    0x20(%rsp),%r14
mov    %r15,%rdi
mov    %r14,%rsi
call   1050 <scanf@plt>
lea    0xead(%rip),%rdi
xor    %eax,%eax
call   1030 <printf@plt>
lea    0x40(%rsp),%rbx
mov    %r15,%rdi
mov    %rbx,%rsi
call   1050 <scanf@plt>
mov    %rsp,%r15
mov    %r14,%rdi
mov    %rbx,%rsi
mov    %r15,%rdx
call   1040 <merge@plt>
lea    0xe8d(%rip),%rdi
mov    %r15,%rsi
xor    %eax,%eax
call   1030 <printf@plt>
xor    %eax,%eax
add    $0x70,%rsp
pop    %rbx
pop    %r14
pop    %r15
ret

LLVM IR (-O0):
@.str = [15 x i8] c"input string1:\00"
@.str.1 = [3 x i8] c"%s\00"
@.str.2 = [15 x i8] c"input string2:\00"
@.str.3 = [18 x i8] c"new string is %s\0A\00"
define i32 @main() {
%1 = alloca i32
%2 = alloca [20 x i8]
%3 = alloca [40 x i8]
%4 = alloca [20 x i8]
store i32 0, i32* %1
%5 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str, i64 0, i64 0))
%6 = bitcast [20 x i8]* %2 to i8**
%7 = call i32 @scanf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0), i8** %6)
%8 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str.2, i64 0, i64 0))
%9 = bitcast [40 x i8]* %3 to i8**
%10 = call i32 @scanf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0), i8** %9)
%11 = getelementptr inbounds [20 x i8], [20 x i8]* %2, i64 0, i64 0
%12 = getelementptr inbounds [40 x i8], [40 x i8]* %3, i64 0, i64 0
%13 = getelementptr inbounds [20 x i8], [20 x i8]* %4, i64 0, i64 0
%14 = getelementptr inbounds [20 x i8], [20 x i8]* %4, i64 0, i64 0
%15 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([18 x i8], [18 x i8]* @.str.3, i64 0, i64 0), i8* %14)
ret i32 0
}

LLVM IR (-O2):
@.str = [15 x i8] c"input string1:\00"
@.str.1 = [3 x i8] c"%s\00"
@.str.2 = [15 x i8] c"input string2:\00"
@.str.3 = [18 x i8] c"new string is %s\0A\00"
define i32 @main() {
%1 = alloca [20 x i8]
%2 = alloca [40 x i8]
%3 = alloca [20 x i8]
%4 = getelementptr inbounds [20 x i8], [20 x i8]* %1, i64 0, i64 0
%5 = getelementptr inbounds [40 x i8], [40 x i8]* %2, i64 0, i64 0
%6 = getelementptr inbounds [20 x i8], [20 x i8]* %3, i64 0, i64 0
%7 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([15 x i8], [15 x i8]* @.str, i64 0, i64 0))
%8 = bitcast [20 x i8]* %1 to i8**
%9 = call i32 @scanf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0), i8** %8)
%10 = call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([15 x i8], [15 x i8]* @.str.2, i64 0, i64 0))
%11 = bitcast [40 x i8]* %2 to i8**
%12 = call i32 @scanf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0), i8** %11)
%13 = call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([18 x i8], [18 x i8]* @.str.3, i64 0, i64 0), i8* %6)
ret i32 0
}