#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 strlen(char const *);
char tolower(char const);
void toLowerCase(const char *str1, char *str2) {
  register int i = 0;
  *(str2 + 0) = '\0';
  for (; i < strlen(str1); i++)
    *(str2 + i) = tolower(*(str1 + i));
  *(str2 + i) = '\0';
}


x86 assembly (clang, -O0):
<toLowerCase>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
movl   $0x0,-0x14(%rbp)
mov    -0x10(%rbp),%rax
movb   $0x0,(%rax)
mov    -0x14(%rbp),%eax
mov    %eax,-0x18(%rbp)
mov    -0x8(%rbp),%rdi
call   1030 <strlen@plt>
mov    %eax,%ecx
mov    -0x18(%rbp),%eax
cmp    %ecx,%eax
jge    1186 <toLowerCase+0x66>
mov    -0x8(%rbp),%rax
movslq -0x14(%rbp),%rcx
movsbl (%rax,%rcx,1),%edi
call   1040 <tolower@plt>
mov    %al,%dl
mov    -0x10(%rbp),%rax
movslq -0x14(%rbp),%rcx
mov    %dl,(%rax,%rcx,1)
mov    -0x14(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x14(%rbp)
jmp    113e <toLowerCase+0x1e>
mov    -0x10(%rbp),%rax
movslq -0x14(%rbp),%rcx
movb   $0x0,(%rax,%rcx,1)
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<toLowerCase>:
push   %r15
push   %r14
push   %rbx
mov    %rsi,%r14
mov    %rdi,%r15
movb   $0x0,(%rsi)
call   1030 <strlen@plt>
xor    %ebx,%ebx
test   %eax,%eax
jle    1161 <toLowerCase+0x41>
nopl   0x0(%rax)
movsbl (%r15,%rbx,1),%edi
call   1040 <tolower@plt>
mov    %al,(%r14,%rbx,1)
add    $0x1,%rbx
mov    %r15,%rdi
call   1030 <strlen@plt>
cltq
cmp    %rax,%rbx
jl     1140 <toLowerCase+0x20>
movb   $0x0,(%r14,%rbx,1)
pop    %rbx
pop    %r14
pop    %r15
ret

LLVM IR (-O0):
define void @toLowerCase(i8* %0, i8* %1) {
%3 = alloca i8*
%4 = alloca i8*
%5 = alloca i32
store i8* %0, i8** %3
store i8* %1, i8** %4
store i32 0, i32* %5
%6 = load i8*, i8** %4
%7 = getelementptr inbounds i8, i8* %6, i64 0
store i8 0, i8* %7
br label %8
8: ; preds = %24, %2
%9 = load i32, i32* %5
%10 = load i8*, i8** %3
%11 = call i32 @strlen(i8* %10)
%12 = icmp slt i32 %9, %11
br i1 %12, label %13, label %27
13: ; preds = %8
%14 = load i8*, i8** %3
%15 = load i32, i32* %5
%16 = sext i32 %15 to i64
%17 = getelementptr inbounds i8, i8* %14, i64 %16
%18 = load i8, i8* %17
%19 = call signext i8 @tolower(i8 signext %18)
%20 = load i8*, i8** %4
%21 = load i32, i32* %5
%22 = sext i32 %21 to i64
%23 = getelementptr inbounds i8, i8* %20, i64 %22
store i8 %19, i8* %23
br label %24
24: ; preds = %13
%25 = load i32, i32* %5
%26 = add nsw i32 %25, 1
store i32 %26, i32* %5
br label %8
27: ; preds = %8
%28 = load i8*, i8** %4
%29 = load i32, i32* %5
%30 = sext i32 %29 to i64
%31 = getelementptr inbounds i8, i8* %28, i64 %30
store i8 0, i8* %31
ret void
}

LLVM IR (-O2):
define void @toLowerCase(i8* %0, i8* nocapture writeonly %1) {
store i8 0, i8* %1
%3 = tail call i32 @strlen(i8* %0)
%4 = icmp sgt i32 %3, 0
br i1 %4, label %5, label %17
5: ; preds = %2, %5
%6 = phi i64 [ %11, %5 ], [ 0, %2 ]
%7 = getelementptr inbounds i8, i8* %0, i64 %6
%8 = load i8, i8* %7
%9 = tail call signext i8 @tolower(i8 signext %8)
%10 = getelementptr inbounds i8, i8* %1, i64 %6
store i8 %9, i8* %10
%11 = add nuw nsw i64 %6, 1
%12 = tail call i32 @strlen(i8* %0)
%13 = sext i32 %12 to i64
%14 = icmp slt i64 %11, %13
br i1 %14, label %5, label %15
15: ; preds = %5
%16 = and i64 %11, 4294967295
br label %17
17: ; preds = %15, %2
%18 = phi i64 [ 0, %2 ], [ %16, %15 ]
%19 = getelementptr inbounds i8, i8* %1, i64 %18
store i8 0, i8* %19
ret void
}