#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*/ perror(char *);
int read(int, char *, int);
int read_n(int fd, char *buf, int n) {
  int readed = 0;
  int ret;
  while (n > readed) {
    ret = read(fd, buf + readed, n - readed);
    if (ret == -1) {
      perror("read_n|read");
      return -1;
    }
    readed += ret;
  }
  return 0;
}


x86 assembly (clang, -O0):
<read_n>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %edi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    %edx,-0x14(%rbp)
movl   $0x0,-0x18(%rbp)
mov    -0x14(%rbp),%eax
cmp    -0x18(%rbp),%eax
jle    1191 <read_n+0x71>
mov    -0x8(%rbp),%edi
mov    -0x10(%rbp),%rsi
movslq -0x18(%rbp),%rax
add    %rax,%rsi
mov    -0x14(%rbp),%edx
sub    -0x18(%rbp),%edx
call   1030 <read@plt>
mov    %eax,-0x1c(%rbp)
cmpl   $0xffffffff,-0x1c(%rbp)
jne    1183 <read_n+0x63>
lea    0xe8e(%rip),%rdi
call   1040 <perror@plt>
movl   $0xffffffff,-0x4(%rbp)
jmp    1198 <read_n+0x78>
mov    -0x1c(%rbp),%eax
add    -0x18(%rbp),%eax
mov    %eax,-0x18(%rbp)
jmp    1139 <read_n+0x19>
movl   $0x0,-0x4(%rbp)
mov    -0x4(%rbp),%eax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<read_n>:
push   %rbp
push   %r15
push   %r14
push   %rbx
push   %rax
test   %edx,%edx
jle    115e <read_n+0x3e>
mov    %edx,%ebx
mov    %rsi,%r14
mov    %edi,%r15d
xor    %ebp,%ebp
cs nopw 0x0(%rax,%rax,1)
nop
movslq %ebp,%rax
lea    (%r14,%rax,1),%rsi
mov    %ebx,%edx
sub    %eax,%edx
mov    %r15d,%edi
call   1030 <read@plt>
cmp    $0xffffffff,%eax
je     116b <read_n+0x4b>
add    %eax,%ebp
cmp    %ebx,%ebp
jl     1140 <read_n+0x20>
xor    %eax,%eax
add    $0x8,%rsp
pop    %rbx
pop    %r14
pop    %r15
pop    %rbp
ret
lea    0xe8e(%rip),%rdi
call   1040 <perror@plt>
mov    $0xffffffff,%eax
jmp    1160 <read_n+0x40>

LLVM IR (-O0):
@.str = [12 x i8] c"read_n|read\00"
define i32 @read_n(i32 %0, i8* %1, i32 %2) {
%4 = alloca i32
%5 = alloca i32
%6 = alloca i8*
%7 = alloca i32
%8 = alloca i32
%9 = alloca i32
store i32 %0, i32* %5
store i8* %1, i8** %6
store i32 %2, i32* %7
store i32 0, i32* %8
br label %10
10: ; preds = %28, %3
%11 = load i32, i32* %7
%12 = load i32, i32* %8
%13 = icmp sgt i32 %11, %12
br i1 %13, label %14, label %32
14: ; preds = %10
%15 = load i32, i32* %5
%16 = load i8*, i8** %6
%17 = load i32, i32* %8
%18 = sext i32 %17 to i64
%19 = getelementptr inbounds i8, i8* %16, i64 %18
%20 = load i32, i32* %7
%21 = load i32, i32* %8
%22 = sub nsw i32 %20, %21
%23 = call i32 @read(i32 %15, i8* %19, i32 %22)
store i32 %23, i32* %9
%24 = load i32, i32* %9
%25 = icmp eq i32 %24, -1
br i1 %25, label %26, label %28
26: ; preds = %14
%27 = call i32 @perror(i8* getelementptr inbounds ([12 x i8], [12 x i8]* @.str, i64 0, i64 0))
store i32 -1, i32* %4
br label %33
28: ; preds = %14
%29 = load i32, i32* %9
%30 = load i32, i32* %8
%31 = add nsw i32 %30, %29
store i32 %31, i32* %8
br label %10
32: ; preds = %10
store i32 0, i32* %4
br label %33
33: ; preds = %32, %26
%34 = load i32, i32* %4
ret i32 %34
}

LLVM IR (-O2):
@.str = [12 x i8] c"read_n|read\00"
define i32 @read_n(i32 %0, i8* nocapture %1, i32 %2) {
%4 = icmp sgt i32 %2, 0
br i1 %4, label %7, label %17
5: ; preds = %7
%6 = icmp slt i32 %14, %2
br i1 %6, label %7, label %17
7: ; preds = %3, %5
%8 = phi i32 [ %14, %5 ], [ 0, %3 ]
%9 = sext i32 %8 to i64
%10 = getelementptr inbounds i8, i8* %1, i64 %9
%11 = sub nsw i32 %2, %8
%12 = tail call i32 @read(i32 %0, i8* %10, i32 %11)
%13 = icmp eq i32 %12, -1
%14 = add nsw i32 %12, %8
br i1 %13, label %15, label %5
15: ; preds = %7
%16 = tail call i32 @perror(i8* getelementptr inbounds ([12 x i8], [12 x i8]* @.str, i64 0, i64 0))
br label %17
17: ; preds = %5, %3, %15
%18 = phi i32 [ -1, %15 ], [ 0, %3 ], [ 0, %5 ]
ret i32 %18
}