#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*/ exit(int);
char *malloc(size_t);
int /*<<< orphan*/ memcpy(char *, char const *, size_t);
int /*<<< orphan*/ perror(char *);
size_t strlen(char const *);
char *string_join(const char *left, const char *right) {
  size_t left_len = strlen(left), right_len = strlen(right);
  char *result;
  if ((result = malloc(left_len + right_len + 1)) == NULL) {
    perror("ERROR: malloc");
    exit(1);
  }
  memcpy(result, left, left_len);
  memcpy(result + left_len, right, right_len);
  result[left_len + right_len] = 0;
  return result;
}


x86 assembly (clang, -O0):
<string_join>:
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    %rax,-0x18(%rbp)
mov    -0x10(%rbp),%rdi
call   1030 <strlen@plt>
mov    %rax,-0x20(%rbp)
mov    -0x18(%rbp),%rdi
add    -0x20(%rbp),%rdi
add    $0x1,%rdi
call   1050 <malloc@plt>
mov    %rax,-0x28(%rbp)
cmp    $0x0,%rax
jne    11af <string_join+0x5f>
lea    0xe60(%rip),%rdi
call   1060 <perror@plt>
mov    $0x1,%edi
call   1070 <exit@plt>
mov    -0x28(%rbp),%rdi
mov    -0x8(%rbp),%rsi
mov    -0x18(%rbp),%rdx
call   1040 <memcpy@plt>
mov    -0x28(%rbp),%rdi
add    -0x18(%rbp),%rdi
mov    -0x10(%rbp),%rsi
mov    -0x20(%rbp),%rdx
call   1040 <memcpy@plt>
mov    -0x28(%rbp),%rax
mov    -0x18(%rbp),%rcx
add    -0x20(%rbp),%rcx
movb   $0x0,(%rax,%rcx,1)
mov    -0x28(%rbp),%rax
add    $0x30,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<string_join>:
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    %rax,%r13
mov    %r14,%rdi
call   1030 <strlen@plt>
mov    %rax,%r12
lea    (%rax,%r13,1),%rdi
add    $0x1,%rdi
call   1050 <malloc@plt>
test   %rax,%rax
je     11c4 <string_join+0x74>
mov    %rax,%rbx
mov    %r12,%rbp
add    %r13,%rbp
mov    %rax,%rdi
mov    %r15,%rsi
mov    %r13,%rdx
call   1040 <memcpy@plt>
mov    %rbx,%rdi
add    %r13,%rdi
mov    %r14,%rsi
mov    %r12,%rdx
call   1040 <memcpy@plt>
movb   $0x0,(%rbx,%rbp,1)
mov    %rbx,%rax
add    $0x8,%rsp
pop    %rbx
pop    %r12
pop    %r13
pop    %r14
pop    %r15
pop    %rbp
ret
lea    0xe35(%rip),%rdi
call   1060 <perror@plt>
mov    $0x1,%edi
call   1070 <exit@plt>

LLVM IR (-O0):
@.str = [14 x i8] c"ERROR: malloc\00"
define i8* @string_join(i8* %0, i8* %1) {
%3 = alloca i8*
%4 = alloca i8*
%5 = alloca i64
%6 = alloca i64
%7 = alloca i8*
store i8* %0, i8** %3
store i8* %1, i8** %4
%8 = load i8*, i8** %3
%9 = call i64 @strlen(i8* %8)
store i64 %9, i64* %5
%10 = load i8*, i8** %4
%11 = call i64 @strlen(i8* %10)
store i64 %11, i64* %6
%12 = load i64, i64* %5
%13 = load i64, i64* %6
%14 = add i64 %12, %13
%15 = add i64 %14, 1
%16 = call i8* @malloc(i64 %15)
store i8* %16, i8** %7
%17 = icmp eq i8* %16, null
br i1 %17, label %18, label %21
18: ; preds = %2
%19 = call i32 @perror(i8* getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0))
%20 = call i32 @exit(i32 1)
unreachable
21: ; preds = %2
%22 = load i8*, i8** %7
%23 = load i8*, i8** %3
%24 = load i64, i64* %5
%25 = call i32 @memcpy(i8* %22, i8* %23, i64 %24)
%26 = load i8*, i8** %7
%27 = load i64, i64* %5
%28 = getelementptr inbounds i8, i8* %26, i64 %27
%29 = load i8*, i8** %4
%30 = load i64, i64* %6
%31 = call i32 @memcpy(i8* %28, i8* %29, i64 %30)
%32 = load i8*, i8** %7
%33 = load i64, i64* %5
%34 = load i64, i64* %6
%35 = add i64 %33, %34
%36 = getelementptr inbounds i8, i8* %32, i64 %35
store i8 0, i8* %36
%37 = load i8*, i8** %7
ret i8* %37
}

LLVM IR (-O2):
@.str = [14 x i8] c"ERROR: malloc\00"
define i8* @string_join(i8* %0, i8* %1) {
%3 = tail call i64 @strlen(i8* dereferenceable(1) %0)
%4 = tail call i64 @strlen(i8* dereferenceable(1) %1)
%5 = add i64 %4, %3
%6 = add i64 %5, 1
%7 = tail call i8* @malloc(i64 %6)
%8 = icmp eq i8* %7, null
br i1 %8, label %9, label %12
9: ; preds = %2
%10 = tail call i32 @perror(i8* getelementptr inbounds ([14 x i8], [14 x i8]* @.str, i64 0, i64 0))
%11 = tail call i32 @exit(i32 1)
unreachable
12: ; preds = %2
%13 = tail call i32 @memcpy(i8* %7, i8* %0, i64 %3)
%14 = getelementptr inbounds i8, i8* %7, i64 %3
%15 = tail call i32 @memcpy(i8* %14, i8* %1, i64 %4)
%16 = getelementptr inbounds i8, i8* %7, i64 %5
store i8 0, i8* %16
ret i8* %7
}