#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(unsigned char *p, int size) {
  int b;
  for (b = size - 1; b >= 0; b--) {
    printf(" %02x", p[b]);
  }
  printf("\n");
}


x86 assembly (clang, -O0):
<printHex>:
push   %rbp
mov    %rsp,%rbp
sub    $0x10,%rsp
mov    %rdi,-0x8(%rbp)
mov    %esi,-0xc(%rbp)
mov    -0xc(%rbp),%eax
sub    $0x1,%eax
mov    %eax,-0x10(%rbp)
cmpl   $0x0,-0x10(%rbp)
jl     115a <printHex+0x4a>
mov    -0x8(%rbp),%rax
movslq -0x10(%rbp),%rcx
movzbl (%rax,%rcx,1),%esi
lea    0xebb(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
mov    -0x10(%rbp),%eax
add    $0xffffffff,%eax
mov    %eax,-0x10(%rbp)
jmp    1128 <printHex+0x18>
lea    0xea5(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
add    $0x10,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<printHex>:
push   %r15
push   %r14
push   %rbx
test   %esi,%esi
jle    115c <printHex+0x3c>
mov    %rdi,%r15
mov    %esi,%ebx
add    $0x1,%rbx
lea    0xec7(%rip),%r14
nopl   0x0(%rax)
lea    -0x2(%rbx),%eax
movzbl (%r15,%rax,1),%esi
mov    %r14,%rdi
xor    %eax,%eax
call   1040 <printf@plt>
add    $0xffffffffffffffff,%rbx
cmp    $0x1,%rbx
ja     1140 <printHex+0x20>
mov    $0xa,%edi
pop    %rbx
pop    %r14
pop    %r15
jmp    1030 <putchar@plt>

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

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