#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(size_t);
int /*<<< orphan*/ strncpy(char *, char const *, size_t);
char *strndup2(const char *str, size_t n) {
  if (!str) {
    return NULL;
  }
  char *buffer = malloc(n + 1);
  if (!buffer) {
    return NULL;
  }
  strncpy(buffer, str, n + 1);
  buffer[n] = '\0';
  return buffer;
}


x86 assembly (clang, -O0):
<strndup2>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %rdi,-0x10(%rbp)
mov    %rsi,-0x18(%rbp)
cmpq   $0x0,-0x10(%rbp)
jne    1148 <strndup2+0x28>
movq   $0x0,-0x8(%rbp)
jmp    119a <strndup2+0x7a>
mov    -0x18(%rbp),%rdi
add    $0x1,%rdi
call   1040 <malloc@plt>
mov    %rax,-0x20(%rbp)
cmpq   $0x0,-0x20(%rbp)
jne    1171 <strndup2+0x51>
movq   $0x0,-0x8(%rbp)
jmp    119a <strndup2+0x7a>
mov    -0x20(%rbp),%rdi
mov    -0x10(%rbp),%rsi
mov    -0x18(%rbp),%rdx
add    $0x1,%rdx
call   1030 <strncpy@plt>
mov    -0x20(%rbp),%rax
mov    -0x18(%rbp),%rcx
movb   $0x0,(%rax,%rcx,1)
mov    -0x20(%rbp),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<strndup2>:
push   %r15
push   %r14
push   %r12
push   %rbx
push   %rax
test   %rdi,%rdi
je     115c <strndup2+0x3c>
mov    %rsi,%r14
mov    %rdi,%r15
lea    0x1(%rsi),%r12
mov    %r12,%rdi
call   1040 <malloc@plt>
test   %rax,%rax
je     115c <strndup2+0x3c>
mov    %rax,%rbx
mov    %rax,%rdi
mov    %r15,%rsi
mov    %r12,%rdx
call   1030 <strncpy@plt>
movb   $0x0,(%rbx,%r14,1)
jmp    115e <strndup2+0x3e>
xor    %ebx,%ebx
mov    %rbx,%rax
add    $0x8,%rsp
pop    %rbx
pop    %r12
pop    %r14
pop    %r15
ret

LLVM IR (-O0):
define i8* @strndup2(i8* %0, i64 %1) {
%3 = alloca i8*
%4 = alloca i8*
%5 = alloca i64
%6 = alloca i8*
store i8* %0, i8** %4
store i64 %1, i64* %5
%7 = load i8*, i8** %4
%8 = icmp ne i8* %7, null
br i1 %8, label %10, label %9
9: ; preds = %2
store i8* null, i8** %3
br label %27
10: ; preds = %2
%11 = load i64, i64* %5
%12 = add i64 %11, 1
%13 = call i8* @malloc(i64 %12)
store i8* %13, i8** %6
%14 = load i8*, i8** %6
%15 = icmp ne i8* %14, null
br i1 %15, label %17, label %16
16: ; preds = %10
store i8* null, i8** %3
br label %27
17: ; preds = %10
%18 = load i8*, i8** %6
%19 = load i8*, i8** %4
%20 = load i64, i64* %5
%21 = add i64 %20, 1
%22 = call i32 @strncpy(i8* %18, i8* %19, i64 %21)
%23 = load i8*, i8** %6
%24 = load i64, i64* %5
%25 = getelementptr inbounds i8, i8* %23, i64 %24
store i8 0, i8* %25
%26 = load i8*, i8** %6
store i8* %26, i8** %3
br label %27
27: ; preds = %17, %16, %9
%28 = load i8*, i8** %3
ret i8* %28
}

LLVM IR (-O2):
define i8* @strndup2(i8* %0, i64 %1) {
%3 = icmp eq i8* %0, null
br i1 %3, label %11, label %4
4: ; preds = %2
%5 = add i64 %1, 1
%6 = tail call i8* @malloc(i64 %5)
%7 = icmp eq i8* %6, null
br i1 %7, label %11, label %8
8: ; preds = %4
%9 = tail call i32 @strncpy(i8* %6, i8* %0, i64 %5)
%10 = getelementptr inbounds i8, i8* %6, i64 %1
store i8 0, i8* %10
br label %11
11: ; preds = %8, %4, %2
%12 = phi i8* [ null, %2 ], [ %6, %8 ], [ null, %4 ]
ret i8* %12
}