#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 */
char *malloc(int);
int /*<<< orphan*/ memcpy(char *, char *, int);
int strlen(char *);
char *concat(char *s1, char *s2) {
  int l1 = strlen(s1), l2 = strlen(s2);
  char *r = malloc(l1 + l2 + 1);
  if (!r)
    return NULL;
  memcpy(r, s1, l1);
  memcpy(r + l1, s2, l2);
  r[l1 + l2] = '\0';
  return r;
}


x86 assembly (clang, -O0):
<concat>:
push   %rbp
mov    %rsp,%rbp
sub    $0x30,%rsp
mov    %rdi,-0x10(%rbp)
mov    %rsi,-0x18(%rbp)
mov    -0x10(%rbp),%rdi
call   1030 <strlen@plt>
mov    %eax,-0x1c(%rbp)
mov    -0x18(%rbp),%rdi
call   1030 <strlen@plt>
mov    %eax,-0x20(%rbp)
mov    -0x1c(%rbp),%edi
add    -0x20(%rbp),%edi
add    $0x1,%edi
call   1050 <malloc@plt>
mov    %rax,-0x28(%rbp)
cmpq   $0x0,-0x28(%rbp)
jne    1182 <concat+0x52>
movq   $0x0,-0x8(%rbp)
jmp    11c2 <concat+0x92>
mov    -0x28(%rbp),%rdi
mov    -0x10(%rbp),%rsi
mov    -0x1c(%rbp),%edx
call   1040 <memcpy@plt>
mov    -0x28(%rbp),%rdi
movslq -0x1c(%rbp),%rax
add    %rax,%rdi
mov    -0x18(%rbp),%rsi
mov    -0x20(%rbp),%edx
call   1040 <memcpy@plt>
mov    -0x28(%rbp),%rax
mov    -0x1c(%rbp),%ecx
add    -0x20(%rbp),%ecx
movslq %ecx,%rcx
movb   $0x0,(%rax,%rcx,1)
mov    -0x28(%rbp),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
add    $0x30,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<concat>:
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),%edi
add    $0x1,%edi
call   1050 <malloc@plt>
mov    %rax,%rbx
test   %rax,%rax
je     1197 <concat+0x67>
mov    %r12d,%ebp
add    %r13d,%ebp
mov    %rbx,%rdi
mov    %r15,%rsi
mov    %r13d,%edx
call   1040 <memcpy@plt>
movslq %r13d,%rax
mov    %rbx,%rdi
add    %rax,%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* @concat(i8* %0, i8* %1) {
%3 = alloca i8*
%4 = alloca i8*
%5 = alloca i8*
%6 = alloca i32
%7 = alloca i32
%8 = alloca i8*
store i8* %0, i8** %4
store i8* %1, i8** %5
%9 = load i8*, i8** %4
%10 = call i32 @strlen(i8* %9)
store i32 %10, i32* %6
%11 = load i8*, i8** %5
%12 = call i32 @strlen(i8* %11)
store i32 %12, i32* %7
%13 = load i32, i32* %6
%14 = load i32, i32* %7
%15 = add nsw i32 %13, %14
%16 = add nsw i32 %15, 1
%17 = call i8* @malloc(i32 %16)
store i8* %17, i8** %8
%18 = load i8*, i8** %8
%19 = icmp ne i8* %18, null
br i1 %19, label %21, label %20
20: ; preds = %2
store i8* null, i8** %3
br label %40
21: ; preds = %2
%22 = load i8*, i8** %8
%23 = load i8*, i8** %4
%24 = load i32, i32* %6
%25 = call i32 @memcpy(i8* %22, i8* %23, i32 %24)
%26 = load i8*, i8** %8
%27 = load i32, i32* %6
%28 = sext i32 %27 to i64
%29 = getelementptr inbounds i8, i8* %26, i64 %28
%30 = load i8*, i8** %5
%31 = load i32, i32* %7
%32 = call i32 @memcpy(i8* %29, i8* %30, i32 %31)
%33 = load i8*, i8** %8
%34 = load i32, i32* %6
%35 = load i32, i32* %7
%36 = add nsw i32 %34, %35
%37 = sext i32 %36 to i64
%38 = getelementptr inbounds i8, i8* %33, i64 %37
store i8 0, i8* %38
%39 = load i8*, i8** %8
store i8* %39, i8** %3
br label %40
40: ; preds = %21, %20
%41 = load i8*, i8** %3
ret i8* %41
}

LLVM IR (-O2):
define i8* @concat(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 i8* @malloc(i32 %6)
%8 = icmp eq i8* %7, null
br i1 %8, label %16, label %9
9: ; preds = %2
%10 = tail call i32 @memcpy(i8* %7, i8* %0, i32 %3)
%11 = sext i32 %3 to i64
%12 = getelementptr inbounds i8, i8* %7, i64 %11
%13 = tail call i32 @memcpy(i8* %12, i8* %1, i32 %4)
%14 = sext i32 %5 to i64
%15 = getelementptr inbounds i8, i8* %7, i64 %14
store i8 0, i8* %15
br label %16
16: ; preds = %2, %9
ret i8* %7
}