#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);
size_t strlen(char const *);
int /*<<< orphan*/ strncpy(char *, char const *, size_t);
char *strndup(const char *s, size_t size) {
  char *ret;
  size_t slen = strlen(s);
  size_t len = slen < size ? slen : size;
  ret = malloc(len + 1);
  if (ret == NULL) {
    return NULL;
  }
  strncpy(ret, s, len);
  ret[len] = '\0';
  return ret;
}


x86 assembly (clang, -O0):
<strndup>:
push   %rbp
mov    %rsp,%rbp
sub    $0x40,%rsp
mov    %rdi,-0x10(%rbp)
mov    %rsi,-0x18(%rbp)
mov    -0x10(%rbp),%rdi
call   1040 <strlen@plt>
mov    %rax,-0x28(%rbp)
mov    -0x28(%rbp),%rax
cmp    -0x18(%rbp),%rax
jae    1168 <strndup+0x38>
mov    -0x28(%rbp),%rax
mov    %rax,-0x38(%rbp)
jmp    1170 <strndup+0x40>
mov    -0x18(%rbp),%rax
mov    %rax,-0x38(%rbp)
mov    -0x38(%rbp),%rax
mov    %rax,-0x30(%rbp)
mov    -0x30(%rbp),%rdi
add    $0x1,%rdi
call   1050 <malloc@plt>
mov    %rax,-0x20(%rbp)
cmpq   $0x0,-0x20(%rbp)
jne    11a1 <strndup+0x71>
movq   $0x0,-0x8(%rbp)
jmp    11c6 <strndup+0x96>
mov    -0x20(%rbp),%rdi
mov    -0x10(%rbp),%rsi
mov    -0x30(%rbp),%rdx
call   1030 <strncpy@plt>
mov    -0x20(%rbp),%rax
mov    -0x30(%rbp),%rcx
movb   $0x0,(%rax,%rcx,1)
mov    -0x20(%rbp),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
add    $0x40,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<strndup>:
push   %r15
push   %r14
push   %rbx
mov    %rsi,%rbx
mov    %rdi,%r14
call   1040 <strlen@plt>
cmp    %rbx,%rax
cmovb  %rax,%rbx
lea    0x1(%rbx),%rdi
call   1050 <malloc@plt>
mov    %rax,%r15
test   %rax,%rax
je     116b <strndup+0x3b>
mov    %r15,%rdi
mov    %r14,%rsi
mov    %rbx,%rdx
call   1030 <strncpy@plt>
movb   $0x0,(%r15,%rbx,1)
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 i8*
%5 = alloca i64
%6 = alloca i8*
%7 = alloca i64
%8 = alloca i64
store i8* %0, i8** %4
store i64 %1, i64* %5
%9 = load i8*, i8** %4
%10 = call i64 @strlen(i8* %9)
store i64 %10, i64* %7
%11 = load i64, i64* %7
%12 = load i64, i64* %5
%13 = icmp ult i64 %11, %12
br i1 %13, label %14, label %16
14: ; preds = %2
%15 = load i64, i64* %7
br label %18
16: ; preds = %2
%17 = load i64, i64* %5
br label %18
18: ; preds = %16, %14
%19 = phi i64 [ %15, %14 ], [ %17, %16 ]
store i64 %19, i64* %8
%20 = load i64, i64* %8
%21 = add i64 %20, 1
%22 = call i8* @malloc(i64 %21)
store i8* %22, i8** %6
%23 = load i8*, i8** %6
%24 = icmp eq i8* %23, null
br i1 %24, label %25, label %26
25: ; preds = %18
store i8* null, i8** %3
br label %35
26: ; preds = %18
%27 = load i8*, i8** %6
%28 = load i8*, i8** %4
%29 = load i64, i64* %8
%30 = call i32 @strncpy(i8* %27, i8* %28, i64 %29)
%31 = load i8*, i8** %6
%32 = load i64, i64* %8
%33 = getelementptr inbounds i8, i8* %31, i64 %32
store i8 0, i8* %33
%34 = load i8*, i8** %6
store i8* %34, i8** %3
br label %35
35: ; preds = %26, %25
%36 = load i8*, i8** %3
ret i8* %36
}

LLVM IR (-O2):
define i8* @strndup(i8* %0, i64 %1) {
%3 = tail call i64 @strlen(i8* dereferenceable(1) %0)
%4 = icmp ult i64 %3, %1
%5 = select i1 %4, i64 %3, i64 %1
%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 @strncpy(i8* %7, i8* %0, i64 %5)
%11 = getelementptr inbounds i8, i8* %7, i64 %5
store i8 0, i8* %11
br label %12
12: ; preds = %2, %9
ret i8* %7
}