#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 *ss_malloc(size_t);
char *strdup(char const *);
size_t strlen(char const *);
int /*<<< orphan*/ strncpy(char *, char const *, size_t);
char *ss_strndup(const char *s, size_t n) {
  size_t len = strlen(s);
  char *ret;
  if (len <= n) {
    return strdup(s);
  }
  ret = ss_malloc(n + 1);
  strncpy(ret, s, n);
  ret[n] = '\0';
  return ret;
}


x86 assembly (clang, -O0):
<ss_strndup>:
push   %rbp
mov    %rsp,%rbp
sub    $0x30,%rsp
mov    %rdi,-0x10(%rbp)
mov    %rsi,-0x18(%rbp)
mov    -0x10(%rbp),%rdi
call   1040 <strlen@plt>
mov    %rax,-0x20(%rbp)
mov    -0x20(%rbp),%rax
cmp    -0x18(%rbp),%rax
ja     117d <ss_strndup+0x3d>
mov    -0x10(%rbp),%rdi
call   1060 <strdup@plt>
mov    %rax,-0x8(%rbp)
jmp    11b3 <ss_strndup+0x73>
mov    -0x18(%rbp),%rdi
add    $0x1,%rdi
call   1050 <ss_malloc@plt>
mov    %rax,-0x28(%rbp)
mov    -0x28(%rbp),%rdi
mov    -0x10(%rbp),%rsi
mov    -0x18(%rbp),%rdx
call   1030 <strncpy@plt>
mov    -0x28(%rbp),%rax
mov    -0x18(%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):
<ss_strndup>:
push   %r15
push   %r14
push   %rbx
mov    %rsi,%rbx
mov    %rdi,%r14
call   1040 <strlen@plt>
cmp    %rbx,%rax
jbe    117d <ss_strndup+0x3d>
lea    0x1(%rbx),%rdi
call   1050 <ss_malloc@plt>
mov    %rax,%r15
mov    %rax,%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
mov    %r14,%rdi
pop    %rbx
pop    %r14
pop    %r15
jmp    1060 <strdup@plt>

LLVM IR (-O0):
define i8* @ss_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 ule i64 %10, %11
br i1 %12, label %13, label %16
13: ; preds = %2
%14 = load i8*, i8** %4
%15 = call i8* @strdup(i8* %14)
store i8* %15, i8** %3
br label %28
16: ; preds = %2
%17 = load i64, i64* %5
%18 = add i64 %17, 1
%19 = call i8* @ss_malloc(i64 %18)
store i8* %19, i8** %7
%20 = load i8*, i8** %7
%21 = load i8*, i8** %4
%22 = load i64, i64* %5
%23 = call i32 @strncpy(i8* %20, i8* %21, i64 %22)
%24 = load i8*, i8** %7
%25 = load i64, i64* %5
%26 = getelementptr inbounds i8, i8* %24, i64 %25
store i8 0, i8* %26
%27 = load i8*, i8** %7
store i8* %27, i8** %3
br label %28
28: ; preds = %16, %13
%29 = load i8*, i8** %3
ret i8* %29
}

LLVM IR (-O2):
define i8* @ss_strndup(i8* %0, i64 %1) {
%3 = tail call i64 @strlen(i8* dereferenceable(1) %0)
%4 = icmp ugt i64 %3, %1
br i1 %4, label %7, label %5
5: ; preds = %2
%6 = tail call i8* @strdup(i8* %0)
br label %12
7: ; preds = %2
%8 = add nuw i64 %1, 1
%9 = tail call i8* @ss_malloc(i64 %8)
%10 = tail call i32 @strncpy(i8* %9, i8* %0, i64 %1)
%11 = getelementptr inbounds i8, i8* %9, i64 %1
store i8 0, i8* %11
br label %12
12: ; preds = %7, %5
%13 = phi i8* [ %6, %5 ], [ %9, %7 ]
ret i8* %13
}