#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*/ memcpy(char *, char const *, size_t);
size_t strlen(char const *);
char *strndup(const char *str, size_t n) {
  size_t len;
  char *copy;
  len = strlen(str);
  if (len > n)
    len = n;
  if (!(copy = malloc(len + 1)))
    return (NULL);
  (void)memcpy(copy, str, len + 1);
  copy[len] = '\0';
  return (copy);
}


x86 assembly (clang, -O0):
<strndup>:
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    %rax,-0x20(%rbp)
mov    -0x20(%rbp),%rax
cmp    -0x18(%rbp),%rax
jbe    1163 <strndup+0x33>
mov    -0x18(%rbp),%rax
mov    %rax,-0x20(%rbp)
mov    -0x20(%rbp),%rdi
add    $0x1,%rdi
call   1050 <malloc@plt>
mov    %rax,-0x28(%rbp)
cmp    $0x0,%rax
jne    118b <strndup+0x5b>
movq   $0x0,-0x8(%rbp)
jmp    11b4 <strndup+0x84>
mov    -0x28(%rbp),%rdi
mov    -0x10(%rbp),%rsi
mov    -0x20(%rbp),%rdx
add    $0x1,%rdx
call   1040 <memcpy@plt>
mov    -0x28(%rbp),%rax
mov    -0x20(%rbp),%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):
<strndup>:
push   %r15
push   %r14
push   %r12
push   %rbx
push   %rax
mov    %rsi,%r15
mov    %rdi,%r14
call   1030 <strlen@plt>
mov    %rax,%rbx
cmp    %r15,%rax
cmova  %r15,%rbx
lea    0x1(%rbx),%r15
mov    %r15,%rdi
call   1050 <malloc@plt>
mov    %rax,%r12
test   %rax,%rax
je     1174 <strndup+0x44>
mov    %r12,%rdi
mov    %r14,%rsi
mov    %r15,%rdx
call   1040 <memcpy@plt>
movb   $0x0,(%r12,%rbx,1)
mov    %r12,%rax
add    $0x8,%rsp
pop    %rbx
pop    %r12
pop    %r14
pop    %r15
ret

LLVM IR (-O0):
define i8* @strndup(i8* %0, i64 %1) {
%3 = alloca i8*
%4 = alloca i8*
%5 = alloca i64
%6 = alloca i64
%7 = alloca i8*
store i8* %0, i8** %4
store i64 %1, i64* %5
%8 = load i8*, i8** %4
%9 = call i64 @strlen(i8* %8)
store i64 %9, i64* %6
%10 = load i64, i64* %6
%11 = load i64, i64* %5
%12 = icmp ugt i64 %10, %11
br i1 %12, label %13, label %15
13: ; preds = %2
%14 = load i64, i64* %5
store i64 %14, i64* %6
br label %15
15: ; preds = %13, %2
%16 = load i64, i64* %6
%17 = add i64 %16, 1
%18 = call i8* @malloc(i64 %17)
store i8* %18, i8** %7
%19 = icmp ne i8* %18, null
br i1 %19, label %21, label %20
20: ; preds = %15
store i8* null, i8** %3
br label %31
21: ; preds = %15
%22 = load i8*, i8** %7
%23 = load i8*, i8** %4
%24 = load i64, i64* %6
%25 = add i64 %24, 1
%26 = call i32 @memcpy(i8* %22, i8* %23, i64 %25)
%27 = load i8*, i8** %7
%28 = load i64, i64* %6
%29 = getelementptr inbounds i8, i8* %27, i64 %28
store i8 0, i8* %29
%30 = load i8*, i8** %7
store i8* %30, i8** %3
br label %31
31: ; preds = %21, %20
%32 = load i8*, i8** %3
ret i8* %32
}

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