#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*/ gets(char *);
int /*<<< orphan*/ printf(char *, ...);
int /*<<< orphan*/ strcpy(char *, char *);
void main(void) {
  char str[50], substr[50];
  printf("Enter 1st string:");
  gets(str);
  printf("\nEnter 2nd string:");
  gets(substr);
  strcpy(str, substr);
  printf("\nOutput:%s\n", str);
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x80,%rsp
lea    0xebe(%rip),%rdi
mov    $0x0,%al
call   1040 <printf@plt>
lea    -0x40(%rbp),%rdi
call   1050 <gets@plt>
lea    0xeb9(%rip),%rdi
mov    $0x0,%al
call   1040 <printf@plt>
lea    -0x80(%rbp),%rdi
call   1050 <gets@plt>
lea    -0x40(%rbp),%rdi
lea    -0x80(%rbp),%rsi
call   1030 <strcpy@plt>
lea    -0x40(%rbp),%rsi
lea    0xea4(%rip),%rdi
mov    $0x0,%al
call   1040 <printf@plt>
add    $0x80,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %r14
push   %rbx
sub    $0x78,%rsp
lea    0xec2(%rip),%rdi
xor    %eax,%eax
call   1040 <printf@plt>
lea    0x40(%rsp),%r14
mov    %r14,%rdi
call   1050 <gets@plt>
lea    0xeb9(%rip),%rdi
xor    %eax,%eax
call   1040 <printf@plt>
mov    %rsp,%rbx
mov    %rbx,%rdi
call   1050 <gets@plt>
mov    %r14,%rdi
mov    %rbx,%rsi
call   1030 <strcpy@plt>
lea    0xea8(%rip),%rdi
mov    %r14,%rsi
xor    %eax,%eax
call   1040 <printf@plt>
add    $0x78,%rsp
pop    %rbx
pop    %r14
ret

LLVM IR (-O0):
@.str = [18 x i8] c"Enter 1st string:\00"
@.str.1 = [19 x i8] c"\0AEnter 2nd string:\00"
@.str.2 = [12 x i8] c"\0AOutput:%s\0A\00"
define void @main() {
%1 = alloca [50 x i8]
%2 = alloca [50 x i8]
%3 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([18 x i8], [18 x i8]* @.str, i64 0, i64 0))
%4 = getelementptr inbounds [50 x i8], [50 x i8]* %1, i64 0, i64 0
%5 = call i32 @gets(i8* %4)
%6 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([19 x i8], [19 x i8]* @.str.1, i64 0, i64 0))
%7 = getelementptr inbounds [50 x i8], [50 x i8]* %2, i64 0, i64 0
%8 = call i32 @gets(i8* %7)
%9 = getelementptr inbounds [50 x i8], [50 x i8]* %1, i64 0, i64 0
%10 = getelementptr inbounds [50 x i8], [50 x i8]* %2, i64 0, i64 0
%11 = call i32 @strcpy(i8* %9, i8* %10)
%12 = getelementptr inbounds [50 x i8], [50 x i8]* %1, i64 0, i64 0
%13 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([12 x i8], [12 x i8]* @.str.2, i64 0, i64 0), i8* %12)
ret void
}

LLVM IR (-O2):
@.str = [18 x i8] c"Enter 1st string:\00"
@.str.1 = [19 x i8] c"\0AEnter 2nd string:\00"
@.str.2 = [12 x i8] c"\0AOutput:%s\0A\00"
define void @main() {
%1 = alloca [50 x i8]
%2 = alloca [50 x i8]
%3 = getelementptr inbounds [50 x i8], [50 x i8]* %1, i64 0, i64 0
%4 = getelementptr inbounds [50 x i8], [50 x i8]* %2, i64 0, i64 0
%5 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([18 x i8], [18 x i8]* @.str, i64 0, i64 0))
%6 = call i32 @gets(i8* %3)
%7 = call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([19 x i8], [19 x i8]* @.str.1, i64 0, i64 0))
%8 = call i32 @gets(i8* %4)
%9 = call i32 @strcpy(i8* %3, i8* %4)
%10 = call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([12 x i8], [12 x i8]* @.str.2, i64 0, i64 0), i8* %3)
ret void
}