#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 *s, size_t n) {
  size_t len = strlen(s);
  char *new;
  if (len > n)
    len = n;
  new = malloc(len + 1);
  if (new) {
    new[len] = '\0';
    memcpy(new, s, len);
  }
  return new;
}


x86 assembly (clang, -O0):
<strndup>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    -0x8(%rbp),%rdi
call   1030 <strlen@plt>
mov    %rax,-0x18(%rbp)
mov    -0x18(%rbp),%rax
cmp    -0x10(%rbp),%rax
jbe    1163 <strndup+0x33>
mov    -0x10(%rbp),%rax
mov    %rax,-0x18(%rbp)
mov    -0x18(%rbp),%rdi
add    $0x1,%rdi
call   1050 <malloc@plt>
mov    %rax,-0x20(%rbp)
cmpq   $0x0,-0x20(%rbp)
je     119c <strndup+0x6c>
mov    -0x20(%rbp),%rax
mov    -0x18(%rbp),%rcx
movb   $0x0,(%rax,%rcx,1)
mov    -0x20(%rbp),%rdi
mov    -0x8(%rbp),%rsi
mov    -0x18(%rbp),%rdx
call   1040 <memcpy@plt>
mov    -0x20(%rbp),%rax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<strndup>:
push   %r15
push   %r14
push   %rbx
mov    %rsi,%r15
mov    %rdi,%r14
call   1030 <strlen@plt>
mov    %rax,%rbx
cmp    %r15,%rax
cmova  %r15,%rbx
lea    0x1(%rbx),%rdi
call   1050 <malloc@plt>
mov    %rax,%r15
test   %rax,%rax
je     116e <strndup+0x3e>
movb   $0x0,(%r15,%rbx,1)
mov    %r15,%rdi
mov    %r14,%rsi
mov    %rbx,%rdx
call   1040 <memcpy@plt>
mov    %r15,%rax
pop    %rbx
pop    %r14
pop    %r15
ret

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

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 = getelementptr inbounds i8, i8* %7, i64 %5
store i8 0, i8* %10
%11 = tail call i32 @memcpy(i8* %7, i8* %0, i64 %5)
br label %12
12: ; preds = %9, %2
ret i8* %7
}