#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 uint32_t;

/* Variables and functions */
int atoi(char *);
int /*<<< orphan*/ printf(char *, ...);
int reverseBits_fast(int);
int reverseBits_std(int);
int main(int argc, char **argv) {
  if (argc < 2) {
    printf("reverseBits <integer>\n");
    return 0;
  }
  uint32_t n = atoi(argv[1]);
  printf("reverseBits of %u is %u.\n", n, reverseBits_std(n));
  printf("reverseBits of %u is %u.\n", n, reverseBits_fast(n));
  return 0;
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
movl   $0x0,-0x4(%rbp)
mov    %edi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
cmpl   $0x2,-0x8(%rbp)
jge    117a <main+0x3a>
lea    0xe99(%rip),%rdi
mov    $0x0,%al
call   1040 <printf@plt>
movl   $0x0,-0x4(%rbp)
jmp    11d3 <main+0x93>
mov    -0x10(%rbp),%rax
mov    0x8(%rax),%rdi
call   1060 <atoi@plt>
mov    %eax,-0x14(%rbp)
mov    -0x14(%rbp),%eax
mov    %eax,-0x1c(%rbp)
mov    -0x14(%rbp),%edi
call   1030 <reverseBits_std@plt>
mov    -0x1c(%rbp),%esi
mov    %eax,%edx
lea    0xe73(%rip),%rdi
mov    $0x0,%al
call   1040 <printf@plt>
mov    -0x14(%rbp),%eax
mov    %eax,-0x18(%rbp)
mov    -0x14(%rbp),%edi
call   1050 <reverseBits_fast@plt>
mov    -0x18(%rbp),%esi
mov    %eax,%edx
lea    0xe52(%rip),%rdi
mov    $0x0,%al
call   1040 <printf@plt>
movl   $0x0,-0x4(%rbp)
mov    -0x4(%rbp),%eax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
push   %r14
push   %rbx
push   %rax
cmp    $0x1,%edi
jg     1167 <main+0x17>
lea    0xeba(%rip),%rdi
call   1030 <puts@plt>
jmp    11a3 <main+0x53>
mov    0x8(%rsi),%rdi
call   1070 <atoi@plt>
mov    %eax,%ebx
mov    %eax,%edi
call   1040 <reverseBits_std@plt>
lea    0xe80(%rip),%r14
mov    %r14,%rdi
mov    %ebx,%esi
mov    %eax,%edx
xor    %eax,%eax
call   1050 <printf@plt>
mov    %ebx,%edi
call   1060 <reverseBits_fast@plt>
mov    %r14,%rdi
mov    %ebx,%esi
mov    %eax,%edx
xor    %eax,%eax
call   1050 <printf@plt>
xor    %eax,%eax
add    $0x8,%rsp
pop    %rbx
pop    %r14
ret

LLVM IR (-O0):
@.str = [23 x i8] c"reverseBits <integer>\0A\00"
@.str.1 = [26 x i8] c"reverseBits of %u is %u.\0A\00"
define i32 @main(i32 %0, i8** %1) {
%3 = alloca i32
%4 = alloca i32
%5 = alloca i8**
%6 = alloca i32
store i32 0, i32* %3
store i32 %0, i32* %4
store i8** %1, i8*** %5
%7 = load i32, i32* %4
%8 = icmp slt i32 %7, 2
br i1 %8, label %9, label %11
9: ; preds = %2
%10 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([23 x i8], [23 x i8]* @.str, i64 0, i64 0))
store i32 0, i32* %3
br label %24
11: ; preds = %2
%12 = load i8**, i8*** %5
%13 = getelementptr inbounds i8*, i8** %12, i64 1
%14 = load i8*, i8** %13
%15 = call i32 @atoi(i8* %14)
store i32 %15, i32* %6
%16 = load i32, i32* %6
%17 = load i32, i32* %6
%18 = call i32 @reverseBits_std(i32 %17)
%19 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([26 x i8], [26 x i8]* @.str.1, i64 0, i64 0), i32 %16, i32 %18)
%20 = load i32, i32* %6
%21 = load i32, i32* %6
%22 = call i32 @reverseBits_fast(i32 %21)
%23 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([26 x i8], [26 x i8]* @.str.1, i64 0, i64 0), i32 %20, i32 %22)
store i32 0, i32* %3
br label %24
24: ; preds = %11, %9
%25 = load i32, i32* %3
ret i32 %25
}

LLVM IR (-O2):
@.str.1 = [26 x i8] c"reverseBits of %u is %u.\0A\00"
@str = [22 x i8] c"reverseBits <integer>\00"
define i32 @main(i32 %0, i8** nocapture %1) {
%3 = icmp slt i32 %0, 2
br i1 %3, label %4, label %6
4: ; preds = %2
%5 = tail call i32 @puts(i8* dereferenceable(1) getelementptr inbounds ([22 x i8], [22 x i8]* @str, i64 0, i64 0))
br label %14
6: ; preds = %2
%7 = getelementptr inbounds i8*, i8** %1, i64 1
%8 = load i8*, i8** %7
%9 = tail call i32 @atoi(i8* %8)
%10 = tail call i32 @reverseBits_std(i32 %9)
%11 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([26 x i8], [26 x i8]* @.str.1, i64 0, i64 0), i32 %9, i32 %10)
%12 = tail call i32 @reverseBits_fast(i32 %9)
%13 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([26 x i8], [26 x i8]* @.str.1, i64 0, i64 0), i32 %9, i32 %12)
br label %14
14: ; preds = %6, %4
ret i32 0
}