#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 */
int /*<<< orphan*/ memcpy(char *, char const *, size_t const);
size_t strlen(char const *);
extern size_t sstrncpy(char *dst, const char *src, size_t dsize) {
  const size_t slen = strlen(src);
  if (dsize != 0) {
    const size_t dlen = dsize > slen ? slen : dsize - 1;
    memcpy(dst, src, dlen);
    dst[dlen] = '\0';
  }
  return slen;
}


x86 assembly (clang, -O0):
<sstrncpy>:
push   %rbp
mov    %rsp,%rbp
sub    $0x30,%rsp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    %rdx,-0x18(%rbp)
mov    -0x10(%rbp),%rdi
call   1030 <strlen@plt>
mov    %rax,-0x20(%rbp)
cmpq   $0x0,-0x18(%rbp)
je     1198 <sstrncpy+0x78>
mov    -0x18(%rbp),%rax
cmp    -0x20(%rbp),%rax
jbe    1167 <sstrncpy+0x47>
mov    -0x20(%rbp),%rax
mov    %rax,-0x30(%rbp)
jmp    1173 <sstrncpy+0x53>
mov    -0x18(%rbp),%rax
sub    $0x1,%rax
mov    %rax,-0x30(%rbp)
mov    -0x30(%rbp),%rax
mov    %rax,-0x28(%rbp)
mov    -0x8(%rbp),%rdi
mov    -0x10(%rbp),%rsi
mov    -0x28(%rbp),%rdx
call   1040 <memcpy@plt>
mov    -0x8(%rbp),%rax
mov    -0x28(%rbp),%rcx
movb   $0x0,(%rax,%rcx,1)
mov    -0x20(%rbp),%rax
add    $0x30,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<sstrncpy>:
push   %r15
push   %r14
push   %r13
push   %r12
push   %rbx
mov    %rdx,%r13
mov    %rsi,%r15
mov    %rdi,%r14
mov    %rsi,%rdi
call   1030 <strlen@plt>
mov    %rax,%r12
test   %r13,%r13
je     1160 <sstrncpy+0x40>
lea    -0x1(%r13),%rbx
cmp    %r13,%r12
cmovb  %r12,%rbx
mov    %r14,%rdi
mov    %r15,%rsi
mov    %rbx,%rdx
call   1040 <memcpy@plt>
movb   $0x0,(%r14,%rbx,1)
mov    %r12,%rax
pop    %rbx
pop    %r12
pop    %r13
pop    %r14
pop    %r15
ret

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

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