#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*/ FILE;

/* Variables and functions */
int /*<<< orphan*/ SEEK_END;
int /*<<< orphan*/ fclose(int /*<<< orphan*/ *);
int /*<<< orphan*/ *fopen(char const *, char *);
int /*<<< orphan*/ fread(char *, int, unsigned long const,
                         int /*<<< orphan*/ *);
int /*<<< orphan*/ fseek(int /*<<< orphan*/ *, int /*<<< orphan*/,
                         int /*<<< orphan*/);
unsigned long ftell(int /*<<< orphan*/ *);
char *malloc(int);
int /*<<< orphan*/ rewind(int /*<<< orphan*/ *);
char *read_file(const char *filename) {
  FILE *fp = fopen(filename, "r");
  if (!fp)
    return NULL;
  fseek(fp, 0, SEEK_END);
  const unsigned long length = ftell(fp);
  rewind(fp);
  char *data = malloc(1 + length);
  fread(data, 1, length, fp);
  fclose(fp);
  data[length] = '\0';
  return data;
}


x86 assembly (clang, -O0):
<read_file>:
push   %rbp
mov    %rsp,%rbp
sub    $0x30,%rsp
mov    %rdi,-0x10(%rbp)
mov    -0x10(%rbp),%rdi
lea    0xe79(%rip),%rsi
call   1090 <fopen@plt>
mov    %rax,-0x18(%rbp)
cmpq   $0x0,-0x18(%rbp)
jne    11a8 <read_file+0x38>
movq   $0x0,-0x8(%rbp)
jmp    1218 <read_file+0xa8>
mov    -0x18(%rbp),%rdi
mov    0x2e35(%rip),%rax
mov    (%rax),%edx
xor    %esi,%esi
call   1080 <fseek@plt>
mov    -0x18(%rbp),%rdi
call   1060 <ftell@plt>
mov    %rax,-0x20(%rbp)
mov    -0x18(%rbp),%rdi
call   1050 <rewind@plt>
mov    -0x20(%rbp),%rax
add    $0x1,%rax
mov    %eax,%edi
call   1070 <malloc@plt>
mov    %rax,-0x28(%rbp)
mov    -0x28(%rbp),%rdi
mov    -0x20(%rbp),%rdx
mov    -0x18(%rbp),%rcx
mov    $0x1,%esi
call   1030 <fread@plt>
mov    -0x18(%rbp),%rdi
call   1040 <fclose@plt>
mov    -0x28(%rbp),%rax
mov    -0x20(%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):
<read_file>:
push   %r15
push   %r14
push   %rbx
lea    0xe84(%rip),%rsi
call   1090 <fopen@plt>
test   %rax,%rax
je     11dd <read_file+0x6d>
mov    %rax,%rbx
mov    0x2e58(%rip),%rax
mov    (%rax),%edx
mov    %rbx,%rdi
xor    %esi,%esi
call   1080 <fseek@plt>
mov    %rbx,%rdi
call   1060 <ftell@plt>
mov    %rax,%r15
mov    %rbx,%rdi
call   1050 <rewind@plt>
lea    0x1(%r15),%edi
call   1070 <malloc@plt>
mov    %rax,%r14
mov    %rax,%rdi
mov    $0x1,%esi
mov    %r15,%rdx
mov    %rbx,%rcx
call   1030 <fread@plt>
mov    %rbx,%rdi
call   1040 <fclose@plt>
movb   $0x0,(%r14,%r15,1)
jmp    11e0 <read_file+0x70>
xor    %r14d,%r14d
mov    %r14,%rax
pop    %rbx
pop    %r14
pop    %r15
ret

LLVM IR (-O0):
@.str = [2 x i8] c"r\00"
@SEEK_END = global i32 0
define i8* @read_file(i8* %0) {
%2 = alloca i8*
%3 = alloca i8*
%4 = alloca i32*
%5 = alloca i64
%6 = alloca i8*
store i8* %0, i8** %3
%7 = load i8*, i8** %3
%8 = call i32* @fopen(i8* %7, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str, i64 0, i64 0))
store i32* %8, i32** %4
%9 = load i32*, i32** %4
%10 = icmp ne i32* %9, null
br i1 %10, label %12, label %11
11: ; preds = %1
store i8* null, i8** %2
br label %34
12: ; preds = %1
%13 = load i32*, i32** %4
%14 = load i32, i32* @SEEK_END
%15 = call i32 @fseek(i32* %13, i32 0, i32 %14)
%16 = load i32*, i32** %4
%17 = call i64 @ftell(i32* %16)
store i64 %17, i64* %5
%18 = load i32*, i32** %4
%19 = call i32 @rewind(i32* %18)
%20 = load i64, i64* %5
%21 = add i64 1, %20
%22 = trunc i64 %21 to i32
%23 = call i8* @malloc(i32 %22)
store i8* %23, i8** %6
%24 = load i8*, i8** %6
%25 = load i64, i64* %5
%26 = load i32*, i32** %4
%27 = call i32 @fread(i8* %24, i32 1, i64 %25, i32* %26)
%28 = load i32*, i32** %4
%29 = call i32 @fclose(i32* %28)
%30 = load i8*, i8** %6
%31 = load i64, i64* %5
%32 = getelementptr inbounds i8, i8* %30, i64 %31
store i8 0, i8* %32
%33 = load i8*, i8** %6
store i8* %33, i8** %2
br label %34
34: ; preds = %12, %11
%35 = load i8*, i8** %2
ret i8* %35
}

LLVM IR (-O2):
@.str = [2 x i8] c"r\00"
@SEEK_END = global i32 0
define noalias i8* @read_file(i8* nocapture %0) {
%2 = tail call i32* @fopen(i8* %0, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str, i64 0, i64 0))
%3 = icmp eq i32* %2, null
br i1 %3, label %15, label %4
4: ; preds = %1
%5 = load i32, i32* @SEEK_END
%6 = tail call i32 @fseek(i32* %2, i32 0, i32 %5)
%7 = tail call i64 @ftell(i32* %2)
%8 = tail call i32 @rewind(i32* %2)
%9 = trunc i64 %7 to i32
%10 = add i32 %9, 1
%11 = tail call i8* @malloc(i32 %10)
%12 = tail call i32 @fread(i8* %11, i32 1, i64 %7, i32* %2)
%13 = tail call i32 @fclose(i32* %2)
%14 = getelementptr inbounds i8, i8* %11, i64 %7
store i8 0, i8* %14
br label %15
15: ; preds = %1, %4
%16 = phi i8* [ %11, %4 ], [ null, %1 ]
ret i8* %16
}