#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*/ SEEK_SET;
int /*<<< orphan*/ fclose(int /*<<< orphan*/ *);
int /*<<< orphan*/ *fopen(char const *, char *);
int /*<<< orphan*/ fread(char *, int, long, int /*<<< orphan*/ *);
int /*<<< orphan*/ free(char *);
int /*<<< orphan*/ fseek(int /*<<< orphan*/ *, int /*<<< orphan*/,
                         int /*<<< orphan*/);
long ftell(int /*<<< orphan*/ *);
char *malloc(long);
int /*<<< orphan*/ memcpy(char *, char *, long);
int /*<<< orphan*/ memset(char *, int /*<<< orphan*/, long);
char *read_file_contents(const char *filename) {
  FILE *fp = fopen(filename, "r");
  if (fp == NULL)
    return NULL;
  fseek(fp, 0, SEEK_END);
  long length = ftell(fp);
  fseek(fp, 0, SEEK_SET);
  char *contents = malloc(length + 1);
  memset(contents, 0, length + 1);
  fread(contents, 1, length, fp);
  fclose(fp);
  if (!contents)
    return contents;
  if (length) {
    char *removednl = malloc(length);
    memset(removednl, 0, length);
    memcpy(removednl, contents, length - 1);
    free(contents);
    return removednl;
  }
  return contents;
}


x86 assembly (clang, -O0):
<read_file_contents>:
push   %rbp
mov    %rsp,%rbp
sub    $0x30,%rsp
mov    %rdi,-0x10(%rbp)
mov    -0x10(%rbp),%rdi
lea    0xe59(%rip),%rsi
call   10b0 <fopen@plt>
mov    %rax,-0x18(%rbp)
cmpq   $0x0,-0x18(%rbp)
jne    11c8 <read_file_contents+0x38>
movq   $0x0,-0x8(%rbp)
jmp    12b2 <read_file_contents+0x122>
mov    -0x18(%rbp),%rdi
mov    0x2e15(%rip),%rax
mov    (%rax),%edx
xor    %esi,%esi
call   10a0 <fseek@plt>
mov    -0x18(%rbp),%rdi
call   1070 <ftell@plt>
mov    %rax,-0x20(%rbp)
mov    -0x18(%rbp),%rdi
mov    0x2de4(%rip),%rax
mov    (%rax),%edx
xor    %esi,%esi
call   10a0 <fseek@plt>
mov    -0x20(%rbp),%rdi
add    $0x1,%rdi
call   1090 <malloc@plt>
mov    %rax,-0x28(%rbp)
mov    -0x28(%rbp),%rdi
mov    -0x20(%rbp),%rdx
add    $0x1,%rdx
xor    %esi,%esi
call   1060 <memset@plt>
mov    -0x28(%rbp),%rdi
mov    -0x20(%rbp),%rdx
mov    -0x18(%rbp),%rcx
mov    $0x1,%esi
call   1040 <fread@plt>
mov    -0x18(%rbp),%rdi
call   1050 <fclose@plt>
cmpq   $0x0,-0x28(%rbp)
jne    1258 <read_file_contents+0xc8>
mov    -0x28(%rbp),%rax
mov    %rax,-0x8(%rbp)
jmp    12b2 <read_file_contents+0x122>
cmpq   $0x0,-0x20(%rbp)
je     12aa <read_file_contents+0x11a>
mov    -0x20(%rbp),%rdi
call   1090 <malloc@plt>
mov    %rax,-0x30(%rbp)
mov    -0x30(%rbp),%rdi
mov    -0x20(%rbp),%rdx
xor    %esi,%esi
call   1060 <memset@plt>
mov    -0x30(%rbp),%rdi
mov    -0x28(%rbp),%rsi
mov    -0x20(%rbp),%rdx
sub    $0x1,%rdx
call   1080 <memcpy@plt>
mov    -0x28(%rbp),%rdi
call   1030 <free@plt>
mov    -0x30(%rbp),%rax
mov    %rax,-0x8(%rbp)
jmp    12b2 <read_file_contents+0x122>
mov    -0x28(%rbp),%rax
mov    %rax,-0x8(%rbp)
mov    -0x8(%rbp),%rax
add    $0x30,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<read_file_contents>:
push   %r15
push   %r14
push   %r12
push   %rbx
push   %rax
lea    0xe61(%rip),%rsi
call   10b0 <fopen@plt>
test   %rax,%rax
je     1259 <read_file_contents+0xc9>
mov    %rax,%rbx
mov    0x2e31(%rip),%rax
mov    (%rax),%edx
mov    %rbx,%rdi
xor    %esi,%esi
call   10a0 <fseek@plt>
mov    %rbx,%rdi
call   1070 <ftell@plt>
mov    %rax,%r14
mov    0x2e03(%rip),%rax
mov    (%rax),%edx
mov    %rbx,%rdi
xor    %esi,%esi
call   10a0 <fseek@plt>
lea    0x1(%r14),%r12
mov    %r12,%rdi
call   1090 <malloc@plt>
mov    %rax,%r15
mov    %rax,%rdi
xor    %esi,%esi
mov    %r12,%rdx
call   1060 <memset@plt>
mov    %r15,%rdi
mov    $0x1,%esi
mov    %r14,%rdx
mov    %rbx,%rcx
call   1040 <fread@plt>
mov    %rbx,%rdi
call   1050 <fclose@plt>
test   %r15,%r15
je     1259 <read_file_contents+0xc9>
test   %r14,%r14
je     125c <read_file_contents+0xcc>
mov    %r14,%rdi
call   1090 <malloc@plt>
mov    %rax,%rbx
mov    %rax,%rdi
xor    %esi,%esi
mov    %r14,%rdx
call   1060 <memset@plt>
add    $0xffffffffffffffff,%r14
mov    %rbx,%rdi
mov    %r15,%rsi
mov    %r14,%rdx
call   1080 <memcpy@plt>
mov    %r15,%rdi
call   1030 <free@plt>
mov    %rbx,%r15
jmp    125c <read_file_contents+0xcc>
xor    %r15d,%r15d
mov    %r15,%rax
add    $0x8,%rsp
pop    %rbx
pop    %r12
pop    %r14
pop    %r15
ret

LLVM IR (-O0):
@.str = [2 x i8] c"r\00"
@SEEK_END = global i32 0
@SEEK_SET = global i32 0
define i8* @read_file_contents(i8* %0) {
%2 = alloca i8*
%3 = alloca i8*
%4 = alloca i32*
%5 = alloca i64
%6 = alloca i8*
%7 = alloca i8*
store i8* %0, i8** %3
%8 = load i8*, i8** %3
%9 = call i32* @fopen(i8* %8, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str, i64 0, i64 0))
store i32* %9, i32** %4
%10 = load i32*, i32** %4
%11 = icmp eq i32* %10, null
br i1 %11, label %12, label %13
12: ; preds = %1
store i8* null, i8** %2
br label %58
13: ; preds = %1
%14 = load i32*, i32** %4
%15 = load i32, i32* @SEEK_END
%16 = call i32 @fseek(i32* %14, i32 0, i32 %15)
%17 = load i32*, i32** %4
%18 = call i64 @ftell(i32* %17)
store i64 %18, i64* %5
%19 = load i32*, i32** %4
%20 = load i32, i32* @SEEK_SET
%21 = call i32 @fseek(i32* %19, i32 0, i32 %20)
%22 = load i64, i64* %5
%23 = add nsw i64 %22, 1
%24 = call i8* @malloc(i64 %23)
store i8* %24, i8** %6
%25 = load i8*, i8** %6
%26 = load i64, i64* %5
%27 = add nsw i64 %26, 1
%28 = call i32 @memset(i8* %25, i32 0, i64 %27)
%29 = load i8*, i8** %6
%30 = load i64, i64* %5
%31 = load i32*, i32** %4
%32 = call i32 @fread(i8* %29, i32 1, i64 %30, i32* %31)
%33 = load i32*, i32** %4
%34 = call i32 @fclose(i32* %33)
%35 = load i8*, i8** %6
%36 = icmp ne i8* %35, null
br i1 %36, label %39, label %37
37: ; preds = %13
%38 = load i8*, i8** %6
store i8* %38, i8** %2
br label %58
39: ; preds = %13
%40 = load i64, i64* %5
%41 = icmp ne i64 %40, 0
br i1 %41, label %42, label %56
42: ; preds = %39
%43 = load i64, i64* %5
%44 = call i8* @malloc(i64 %43)
store i8* %44, i8** %7
%45 = load i8*, i8** %7
%46 = load i64, i64* %5
%47 = call i32 @memset(i8* %45, i32 0, i64 %46)
%48 = load i8*, i8** %7
%49 = load i8*, i8** %6
%50 = load i64, i64* %5
%51 = sub nsw i64 %50, 1
%52 = call i32 @memcpy(i8* %48, i8* %49, i64 %51)
%53 = load i8*, i8** %6
%54 = call i32 @free(i8* %53)
%55 = load i8*, i8** %7
store i8* %55, i8** %2
br label %58
56: ; preds = %39
%57 = load i8*, i8** %6
store i8* %57, i8** %2
br label %58
58: ; preds = %56, %42, %37, %12
%59 = load i8*, i8** %2
ret i8* %59
}

LLVM IR (-O2):
@.str = [2 x i8] c"r\00"
@SEEK_END = global i32 0
@SEEK_SET = global i32 0
define i8* @read_file_contents(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 %24, 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 = load i32, i32* @SEEK_SET
%9 = tail call i32 @fseek(i32* %2, i32 0, i32 %8)
%10 = add nsw i64 %7, 1
%11 = tail call i8* @malloc(i64 %10)
%12 = tail call i32 @memset(i8* %11, i32 0, i64 %10)
%13 = tail call i32 @fread(i8* %11, i32 1, i64 %7, i32* %2)
%14 = tail call i32 @fclose(i32* %2)
%15 = icmp eq i8* %11, null
br i1 %15, label %24, label %16
16: ; preds = %4
%17 = icmp eq i64 %7, 0
br i1 %17, label %24, label %18
18: ; preds = %16
%19 = tail call i8* @malloc(i64 %7)
%20 = tail call i32 @memset(i8* %19, i32 0, i64 %7)
%21 = add nsw i64 %7, -1
%22 = tail call i32 @memcpy(i8* %19, i8* %11, i64 %21)
%23 = tail call i32 @free(i8* %11)
br label %24
24: ; preds = %18, %4, %16, %1
%25 = phi i8* [ null, %1 ], [ %19, %18 ], [ null, %4 ], [ %11, %16 ]
ret i8* %25
}