#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 uint8_t;

/* Variables and functions */
int /*<<< orphan*/ printf(char *, ...);
void printhex(char *description, uint8_t *input, int length) {
  int i;
  printf("%s: ", description);
  for (i = 0; i < length; i++) {
    printf("%02x", input[i]);
  }
  printf("\n");
}


x86 assembly (clang, -O0):
<printhex>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    %edx,-0x14(%rbp)
mov    -0x8(%rbp),%rsi
lea    0xed2(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
movl   $0x0,-0x18(%rbp)
mov    -0x18(%rbp),%eax
cmp    -0x14(%rbp),%eax
jge    116f <printhex+0x5f>
mov    -0x10(%rbp),%rax
movslq -0x18(%rbp),%rcx
mov    (%rax,%rcx,4),%esi
lea    0xeab(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
mov    -0x18(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x18(%rbp)
jmp    113c <printhex+0x2c>
lea    0xe94(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<printhex>:
push   %rbp
push   %r15
push   %r14
push   %rbx
push   %rax
mov    %edx,%ebp
mov    %rsi,%r15
mov    %rdi,%rsi
lea    0xeca(%rip),%rdi
xor    %eax,%eax
call   1040 <printf@plt>
test   %ebp,%ebp
jle    1167 <printhex+0x47>
mov    %ebp,%ebp
lea    0xebb(%rip),%r14
xor    %ebx,%ebx
nopl   0x0(%rax)
mov    (%r15,%rbx,4),%esi
mov    %r14,%rdi
xor    %eax,%eax
call   1040 <printf@plt>
add    $0x1,%rbx
cmp    %rbx,%rbp
jne    1150 <printhex+0x30>
mov    $0xa,%edi
add    $0x8,%rsp
pop    %rbx
pop    %r14
pop    %r15
pop    %rbp
jmp    1030 <putchar@plt>

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