#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 */
typedef int /*<<< orphan*/ buf;

/* Variables and functions */
int /*<<< orphan*/ fatal(char *);
int read(int, char *, int);
int write(int, char *, int);
void copy_fd(int fd_in, int fd_out) {
  char buf[10240];
  int n;
  while ((n = read(fd_in, buf, sizeof(buf))) > 0) {
    if (write(fd_out, buf, n) != n) {
      fatal("Failed to copy fd");
    }
  }
}


x86 assembly (clang, -O0):
<copy_fd>:
push   %rbp
mov    %rsp,%rbp
sub    $0x2820,%rsp
mov    %edi,-0x4(%rbp)
mov    %esi,-0x8(%rbp)
mov    -0x4(%rbp),%edi
lea    -0x2810(%rbp),%rsi
mov    $0x2800,%edx
call   1040 <read@plt>
mov    %eax,-0x2814(%rbp)
cmp    $0x0,%eax
jle    1196 <copy_fd+0x66>
mov    -0x8(%rbp),%edi
lea    -0x2810(%rbp),%rsi
mov    -0x2814(%rbp),%edx
call   1030 <write@plt>
cmp    -0x2814(%rbp),%eax
je     1191 <copy_fd+0x61>
lea    0xe74(%rip),%rdi
call   1050 <fatal@plt>
jmp    1141 <copy_fd+0x11>
add    $0x2820,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<copy_fd>:
push   %rbp
push   %r15
push   %r14
push   %r12
push   %rbx
sub    $0x2800,%rsp
mov    %esi,%r14d
mov    %edi,%r12d
mov    %rsp,%rsi
mov    $0x2800,%edx
call   1040 <read@plt>
test   %eax,%eax
jle    11a1 <copy_fd+0x71>
mov    %eax,%ebp
mov    %rsp,%rbx
lea    0xe9e(%rip),%r15
jmp    1186 <copy_fd+0x56>
cs nopw 0x0(%rax,%rax,1)
xchg   %ax,%ax
mov    %r12d,%edi
mov    %rbx,%rsi
mov    $0x2800,%edx
call   1040 <read@plt>
mov    %eax,%ebp
test   %eax,%eax
jle    11a1 <copy_fd+0x71>
mov    %r14d,%edi
mov    %rbx,%rsi
mov    %ebp,%edx
call   1030 <write@plt>
cmp    %ebp,%eax
je     1170 <copy_fd+0x40>
mov    %r15,%rdi
call   1050 <fatal@plt>
jmp    1170 <copy_fd+0x40>
add    $0x2800,%rsp
pop    %rbx
pop    %r12
pop    %r14
pop    %r15
pop    %rbp
ret

LLVM IR (-O0):
@.str = [18 x i8] c"Failed to copy fd\00"
define void @copy_fd(i32 %0, i32 %1) {
%3 = alloca i32
%4 = alloca i32
%5 = alloca [10240 x i8]
%6 = alloca i32
store i32 %0, i32* %3
store i32 %1, i32* %4
br label %7
7: ; preds = %21, %2
%8 = load i32, i32* %3
%9 = getelementptr inbounds [10240 x i8], [10240 x i8]* %5, i64 0, i64 0
%10 = call i32 @read(i32 %8, i8* %9, i32 10240)
store i32 %10, i32* %6
%11 = icmp sgt i32 %10, 0
br i1 %11, label %12, label %22
12: ; preds = %7
%13 = load i32, i32* %4
%14 = getelementptr inbounds [10240 x i8], [10240 x i8]* %5, i64 0, i64 0
%15 = load i32, i32* %6
%16 = call i32 @write(i32 %13, i8* %14, i32 %15)
%17 = load i32, i32* %6
%18 = icmp ne i32 %16, %17
br i1 %18, label %19, label %21
19: ; preds = %12
%20 = call i32 @fatal(i8* getelementptr inbounds ([18 x i8], [18 x i8]* @.str, i64 0, i64 0))
br label %21
21: ; preds = %19, %12
br label %7
22: ; preds = %7
ret void
}

LLVM IR (-O2):
@.str = [18 x i8] c"Failed to copy fd\00"
define void @copy_fd(i32 %0, i32 %1) {
%3 = alloca [10240 x i8]
%4 = getelementptr inbounds [10240 x i8], [10240 x i8]* %3, i64 0, i64 0
%5 = call i32 @read(i32 %0, i8* %4, i32 10240)
%6 = icmp sgt i32 %5, 0
br i1 %6, label %7, label %16
7: ; preds = %2, %13
%8 = phi i32 [ %14, %13 ], [ %5, %2 ]
%9 = call i32 @write(i32 %1, i8* %4, i32 %8)
%10 = icmp eq i32 %9, %8
br i1 %10, label %13, label %11
11: ; preds = %7
%12 = tail call i32 @fatal(i8* getelementptr inbounds ([18 x i8], [18 x i8]* @.str, i64 0, i64 0))
br label %13
13: ; preds = %11, %7
%14 = call i32 @read(i32 %0, i8* %4, i32 10240)
%15 = icmp sgt i32 %14, 0
br i1 %15, label %7, label %16
16: ; preds = %13, %2
ret void
}