#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 */
scalar_t__ malloc(int);
int /*<<< orphan*/ memcpy(char *, char const *, int);
int strlen(char const *);
char *concatenate(const char *a, const char *b) {
  int a_len = strlen(a), b_len = strlen(b);
  int buf_size = a_len + b_len + 1;
  char *result = (char *)malloc(buf_size);
  memcpy(result, a, a_len);
  memcpy(result + a_len, b, b_len);
  result[a_len + b_len] = 0;
  return result;
}


x86 assembly (clang, -O0):
<concatenate>:
push   %rbp
mov    %rsp,%rbp
sub    $0x30,%rsp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    -0x8(%rbp),%rdi
call   1030 <strlen@plt>
mov    %eax,-0x14(%rbp)
mov    -0x10(%rbp),%rdi
call   1030 <strlen@plt>
mov    %eax,-0x18(%rbp)
mov    -0x14(%rbp),%eax
add    -0x18(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x1c(%rbp)
mov    -0x1c(%rbp),%edi
call   1050 <malloc@plt>
mov    %rax,-0x28(%rbp)
mov    -0x28(%rbp),%rdi
mov    -0x8(%rbp),%rsi
mov    -0x14(%rbp),%edx
call   1040 <memcpy@plt>
mov    -0x28(%rbp),%rdi
movslq -0x14(%rbp),%rax
add    %rax,%rdi
mov    -0x10(%rbp),%rsi
mov    -0x18(%rbp),%edx
call   1040 <memcpy@plt>
mov    -0x28(%rbp),%rax
mov    -0x14(%rbp),%ecx
add    -0x18(%rbp),%ecx
movslq %ecx,%rcx
movb   $0x0,(%rax,%rcx,1)
mov    -0x28(%rbp),%rax
add    $0x30,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<concatenate>:
push   %rbp
push   %r15
push   %r14
push   %r13
push   %r12
push   %rbx
push   %rax
mov    %rsi,%r14
mov    %rdi,%r15
call   1030 <strlen@plt>
mov    %eax,%r13d
mov    %r14,%rdi
call   1030 <strlen@plt>
mov    %eax,%r12d
lea    (%r12,%r13,1),%ebp
lea    (%r12,%r13,1),%edi
add    $0x1,%edi
call   1050 <malloc@plt>
mov    %rax,%rbx
mov    %rax,%rdi
mov    %r15,%rsi
mov    %r13d,%edx
call   1040 <memcpy@plt>
movslq %r13d,%rdi
add    %rbx,%rdi
mov    %r14,%rsi
mov    %r12d,%edx
call   1040 <memcpy@plt>
movslq %ebp,%rax
movb   $0x0,(%rbx,%rax,1)
mov    %rbx,%rax
add    $0x8,%rsp
pop    %rbx
pop    %r12
pop    %r13
pop    %r14
pop    %r15
pop    %rbp
ret

LLVM IR (-O0):
define i8* @concatenate(i8* %0, i8* %1) {
%3 = alloca i8*
%4 = alloca i8*
%5 = alloca i32
%6 = alloca i32
%7 = alloca i32
%8 = alloca i8*
store i8* %0, i8** %3
store i8* %1, i8** %4
%9 = load i8*, i8** %3
%10 = call i32 @strlen(i8* %9)
store i32 %10, i32* %5
%11 = load i8*, i8** %4
%12 = call i32 @strlen(i8* %11)
store i32 %12, i32* %6
%13 = load i32, i32* %5
%14 = load i32, i32* %6
%15 = add nsw i32 %13, %14
%16 = add nsw i32 %15, 1
store i32 %16, i32* %7
%17 = load i32, i32* %7
%18 = call i64 @malloc(i32 %17)
%19 = inttoptr i64 %18 to i8*
store i8* %19, i8** %8
%20 = load i8*, i8** %8
%21 = load i8*, i8** %3
%22 = load i32, i32* %5
%23 = call i32 @memcpy(i8* %20, i8* %21, i32 %22)
%24 = load i8*, i8** %8
%25 = load i32, i32* %5
%26 = sext i32 %25 to i64
%27 = getelementptr inbounds i8, i8* %24, i64 %26
%28 = load i8*, i8** %4
%29 = load i32, i32* %6
%30 = call i32 @memcpy(i8* %27, i8* %28, i32 %29)
%31 = load i8*, i8** %8
%32 = load i32, i32* %5
%33 = load i32, i32* %6
%34 = add nsw i32 %32, %33
%35 = sext i32 %34 to i64
%36 = getelementptr inbounds i8, i8* %31, i64 %35
store i8 0, i8* %36
%37 = load i8*, i8** %8
ret i8* %37
}

LLVM IR (-O2):
define i8* @concatenate(i8* %0, i8* %1) {
%3 = tail call i32 @strlen(i8* %0)
%4 = tail call i32 @strlen(i8* %1)
%5 = add nsw i32 %4, %3
%6 = add nsw i32 %5, 1
%7 = tail call i64 @malloc(i32 %6)
%8 = inttoptr i64 %7 to i8*
%9 = tail call i32 @memcpy(i8* %8, i8* %0, i32 %3)
%10 = sext i32 %3 to i64
%11 = getelementptr inbounds i8, i8* %8, i64 %10
%12 = tail call i32 @memcpy(i8* %11, i8* %1, i32 %4)
%13 = sext i32 %5 to i64
%14 = getelementptr inbounds i8, i8* %8, i64 %13
store i8 0, i8* %14
ret i8* %8
}