#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*/ printf(char *, ...);
void printhex(void *p, int size) {
  unsigned char *ip = (unsigned char *)p;
  printf("0x");
  for (int i = size - 1; i >= 0; i--) {
    printf("%02x", *(ip + i));
  }
  printf("\n");
}


x86 assembly (clang, -O0):
<printhex>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %rdi,-0x8(%rbp)
mov    %esi,-0xc(%rbp)
mov    -0x8(%rbp),%rax
mov    %rax,-0x18(%rbp)
lea    0xed2(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
mov    -0xc(%rbp),%eax
sub    $0x1,%eax
mov    %eax,-0x1c(%rbp)
cmpl   $0x0,-0x1c(%rbp)
jl     1170 <printhex+0x60>
mov    -0x18(%rbp),%rax
movslq -0x1c(%rbp),%rcx
movzbl (%rax,%rcx,1),%esi
lea    0xea8(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
mov    -0x1c(%rbp),%eax
add    $0xffffffff,%eax
mov    %eax,-0x1c(%rbp)
jmp    113e <printhex+0x2e>
lea    0xe91(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<printhex>:
push   %rbp
push   %r14
push   %rbx
mov    %esi,%ebp
mov    %rdi,%rbx
lea    0xed0(%rip),%rdi
xor    %eax,%eax
call   1040 <printf@plt>
test   %ebp,%ebp
jle    116b <printhex+0x4b>
mov    %ebp,%ebp
add    $0x1,%rbp
lea    0xebb(%rip),%r14
nopl   0x0(%rax,%rax,1)
lea    -0x2(%rbp),%eax
movzbl (%rbx,%rax,1),%esi
mov    %r14,%rdi
xor    %eax,%eax
call   1040 <printf@plt>
add    $0xffffffffffffffff,%rbp
cmp    $0x1,%rbp
ja     1150 <printhex+0x30>
mov    $0xa,%edi
pop    %rbx
pop    %r14
pop    %rbp
jmp    1030 <putchar@plt>

LLVM IR (-O0):
@.str = [3 x i8] c"0x\00"
@.str.1 = [5 x i8] c"%02x\00"
@.str.2 = [2 x i8] c"\0A\00"
define void @printhex(i8* %0, i32 %1) {
%3 = alloca i8*
%4 = alloca i32
%5 = alloca i8*
%6 = alloca i32
store i8* %0, i8** %3
store i32 %1, i32* %4
%7 = load i8*, i8** %3
store i8* %7, i8** %5
%8 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0))
%9 = load i32, i32* %4
%10 = sub nsw i32 %9, 1
store i32 %10, i32* %6
br label %11
11: ; preds = %22, %2
%12 = load i32, i32* %6
%13 = icmp sge i32 %12, 0
br i1 %13, label %14, label %25
14: ; preds = %11
%15 = load i8*, i8** %5
%16 = load i32, i32* %6
%17 = sext i32 %16 to i64
%18 = getelementptr inbounds i8, i8* %15, i64 %17
%19 = load i8, i8* %18
%20 = zext i8 %19 to i32
%21 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([5 x i8], [5 x i8]* @.str.1, i64 0, i64 0), i32 %20)
br label %22
22: ; preds = %14
%23 = load i32, i32* %6
%24 = add nsw i32 %23, -1
store i32 %24, i32* %6
br label %11
25: ; preds = %11
%26 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str.2, i64 0, i64 0))
ret void
}

LLVM IR (-O2):
@.str = [3 x i8] c"0x\00"
@.str.1 = [5 x i8] c"%02x\00"
define void @printhex(i8* nocapture %0, i32 %1) {
%3 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([3 x i8], [3 x i8]* @.str, i64 0, i64 0))
%4 = icmp sgt i32 %1, 0
br i1 %4, label %5, label %7
5: ; preds = %2
%6 = zext i32 %1 to i64
br label %9
7: ; preds = %9, %2
%8 = tail call i32 @putchar(i32 10)
ret void
9: ; preds = %5, %9
%10 = phi i64 [ %6, %5 ], [ %11, %9 ]
%11 = add nsw i64 %10, -1
%12 = and i64 %11, 4294967295
%13 = getelementptr inbounds i8, i8* %0, i64 %12
%14 = load i8, i8* %13
%15 = zext i8 %14 to i32
%16 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([5 x i8], [5 x i8]* @.str.1, i64 0, i64 0), i32 %15)
%17 = icmp ugt i64 %10, 1
br i1 %17, label %9, label %7
}