#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*/ F_SETFL;
int O_NDELAY;
int O_NOCTTY;
int O_RDWR;
int /*<<< orphan*/ fcntl(int, int /*<<< orphan*/, int /*<<< orphan*/);
int open(char *, int);
int /*<<< orphan*/ perror(char *);
int open_port(void) {
  char *portname = "/dev/ttyUSB0";
  int fd;
  fd = open(portname, O_RDWR | O_NOCTTY | O_NDELAY);
  if (fd == -1) {
    perror("open_port: Unable to open port - ");
  } else
    fcntl(fd, F_SETFL, 0);
  return (fd);
}


x86 assembly (clang, -O0):
<open_port>:
push   %rbp
mov    %rsp,%rbp
sub    $0x10,%rsp
lea    0xec1(%rip),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rdi
mov    0x2e9a(%rip),%rax
mov    (%rax),%esi
mov    0x2e81(%rip),%rax
or     (%rax),%esi
mov    0x2e68(%rip),%rax
or     (%rax),%esi
call   1040 <open@plt>
mov    %eax,-0xc(%rbp)
cmpl   $0xffffffff,-0xc(%rbp)
jne    1185 <open_port+0x55>
lea    0xe92(%rip),%rdi
call   1050 <perror@plt>
jmp    1198 <open_port+0x68>
mov    -0xc(%rbp),%edi
mov    0x2e41(%rip),%rax
mov    (%rax),%esi
xor    %edx,%edx
call   1030 <fcntl@plt>
mov    -0xc(%rbp),%eax
add    $0x10,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<open_port>:
push   %rbx
mov    0x2eb0(%rip),%rax
mov    0x2e99(%rip),%rcx
mov    (%rcx),%esi
or     (%rax),%esi
mov    0x2e7e(%rip),%rax
or     (%rax),%esi
lea    0xead(%rip),%rdi
call   1040 <open@plt>
mov    %eax,%ebx
cmp    $0xffffffff,%eax
je     1175 <open_port+0x45>
mov    0x2e6a(%rip),%rax
mov    (%rax),%esi
mov    %ebx,%edi
xor    %edx,%edx
call   1030 <fcntl@plt>
mov    %ebx,%eax
pop    %rbx
ret
lea    0xe91(%rip),%rdi
call   1050 <perror@plt>
jmp    1171 <open_port+0x41>

LLVM IR (-O0):
@.str = [13 x i8] c"/dev/ttyUSB0\00"
@O_RDWR = global i32 0
@O_NOCTTY = global i32 0
@O_NDELAY = global i32 0
@.str.1 = [34 x i8] c"open_port: Unable to open port - \00"
@F_SETFL = global i32 0
define i32 @open_port() {
%1 = alloca i8*
%2 = alloca i32
store i8* getelementptr inbounds ([13 x i8], [13 x i8]* @.str, i64 0, i64 0), i8** %1
%3 = load i8*, i8** %1
%4 = load i32, i32* @O_RDWR
%5 = load i32, i32* @O_NOCTTY
%6 = or i32 %4, %5
%7 = load i32, i32* @O_NDELAY
%8 = or i32 %6, %7
%9 = call i32 @open(i8* %3, i32 %8)
store i32 %9, i32* %2
%10 = load i32, i32* %2
%11 = icmp eq i32 %10, -1
br i1 %11, label %12, label %14
12: ; preds = %0
%13 = call i32 @perror(i8* getelementptr inbounds ([34 x i8], [34 x i8]* @.str.1, i64 0, i64 0))
br label %18
14: ; preds = %0
%15 = load i32, i32* %2
%16 = load i32, i32* @F_SETFL
%17 = call i32 @fcntl(i32 %15, i32 %16, i32 0)
br label %18
18: ; preds = %14, %12
%19 = load i32, i32* %2
ret i32 %19
}

LLVM IR (-O2):
@.str = [13 x i8] c"/dev/ttyUSB0\00"
@O_RDWR = global i32 0
@O_NOCTTY = global i32 0
@O_NDELAY = global i32 0
@.str.1 = [34 x i8] c"open_port: Unable to open port - \00"
@F_SETFL = global i32 0
define i32 @open_port() {
%1 = load i32, i32* @O_RDWR
%2 = load i32, i32* @O_NOCTTY
%3 = or i32 %2, %1
%4 = load i32, i32* @O_NDELAY
%5 = or i32 %3, %4
%6 = tail call i32 @open(i8* getelementptr inbounds ([13 x i8], [13 x i8]* @.str, i64 0, i64 0), i32 %5)
%7 = icmp eq i32 %6, -1
br i1 %7, label %8, label %10
8: ; preds = %0
%9 = tail call i32 @perror(i8* getelementptr inbounds ([34 x i8], [34 x i8]* @.str.1, i64 0, i64 0))
br label %13
10: ; preds = %0
%11 = load i32, i32* @F_SETFL
%12 = tail call i32 @fcntl(i32 %6, i32 %11, i32 0)
br label %13
13: ; preds = %10, %8
ret i32 %6
}