#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 */
char *malloc(int);
int strlen(char *);
char tolower(char);
char *str_to_lower_case(char str[]) {
  int i = 0;
  char *buffer;
  buffer = malloc(sizeof(char) * strlen(str) + 1);
  do {
    buffer[i] = tolower(str[i]);
    ++i;
  } while (str[i] != '\0');
  buffer[i] = '\0';
  return buffer;
}


x86 assembly (clang, -O0):
<str_to_lower_case>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %rdi,-0x8(%rbp)
movl   $0x0,-0xc(%rbp)
mov    -0x8(%rbp),%rdi
call   1030 <strlen@plt>
cltq
shl    $0x0,%rax
add    $0x1,%rax
mov    %eax,%edi
call   1050 <malloc@plt>
mov    %rax,-0x18(%rbp)
mov    -0x8(%rbp),%rax
movslq -0xc(%rbp),%rcx
movsbl (%rax,%rcx,1),%edi
call   1040 <tolower@plt>
mov    %al,%dl
mov    -0x18(%rbp),%rax
movslq -0xc(%rbp),%rcx
mov    %dl,(%rax,%rcx,1)
mov    -0xc(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0xc(%rbp)
mov    -0x8(%rbp),%rax
movslq -0xc(%rbp),%rcx
movsbl (%rax,%rcx,1),%eax
cmp    $0x0,%eax
jne    1161 <str_to_lower_case+0x31>
mov    -0x18(%rbp),%rax
movslq -0xc(%rbp),%rcx
movb   $0x0,(%rax,%rcx,1)
mov    -0x18(%rbp),%rax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<str_to_lower_case>:
push   %r15
push   %r14
push   %rbx
mov    %rdi,%r14
call   1030 <strlen@plt>
lea    0x1(%rax),%edi
call   1050 <malloc@plt>
mov    %rax,%r15
mov    (%r14),%al
xor    %ebx,%ebx
nopl   (%rax)
movsbl %al,%edi
call   1040 <tolower@plt>
mov    %al,(%r15,%rbx,1)
movzbl 0x1(%r14,%rbx,1),%eax
add    $0x1,%rbx
test   %al,%al
jne    1150 <str_to_lower_case+0x20>
mov    %ebx,%eax
movb   $0x0,(%r15,%rax,1)
mov    %r15,%rax
pop    %rbx
pop    %r14
pop    %r15
ret

LLVM IR (-O0):
define i8* @str_to_lower_case(i8* %0) {
%2 = alloca i8*
%3 = alloca i32
%4 = alloca i8*
store i8* %0, i8** %2
store i32 0, i32* %3
%5 = load i8*, i8** %2
%6 = call i32 @strlen(i8* %5)
%7 = sext i32 %6 to i64
%8 = mul i64 1, %7
%9 = add i64 %8, 1
%10 = trunc i64 %9 to i32
%11 = call i8* @malloc(i32 %10)
store i8* %11, i8** %4
br label %12
12: ; preds = %25, %1
%13 = load i8*, i8** %2
%14 = load i32, i32* %3
%15 = sext i32 %14 to i64
%16 = getelementptr inbounds i8, i8* %13, i64 %15
%17 = load i8, i8* %16
%18 = call signext i8 @tolower(i8 signext %17)
%19 = load i8*, i8** %4
%20 = load i32, i32* %3
%21 = sext i32 %20 to i64
%22 = getelementptr inbounds i8, i8* %19, i64 %21
store i8 %18, i8* %22
%23 = load i32, i32* %3
%24 = add nsw i32 %23, 1
store i32 %24, i32* %3
br label %25
25: ; preds = %12
%26 = load i8*, i8** %2
%27 = load i32, i32* %3
%28 = sext i32 %27 to i64
%29 = getelementptr inbounds i8, i8* %26, i64 %28
%30 = load i8, i8* %29
%31 = sext i8 %30 to i32
%32 = icmp ne i32 %31, 0
br i1 %32, label %12, label %33
33: ; preds = %25
%34 = load i8*, i8** %4
%35 = load i32, i32* %3
%36 = sext i32 %35 to i64
%37 = getelementptr inbounds i8, i8* %34, i64 %36
store i8 0, i8* %37
%38 = load i8*, i8** %4
ret i8* %38
}

LLVM IR (-O2):
define noalias i8* @str_to_lower_case(i8* %0) {
%2 = tail call i32 @strlen(i8* %0)
%3 = add i32 %2, 1
%4 = tail call i8* @malloc(i32 %3)
%5 = load i8, i8* %0
br label %6
6: ; preds = %6, %1
%7 = phi i8 [ %13, %6 ], [ %5, %1 ]
%8 = phi i64 [ %11, %6 ], [ 0, %1 ]
%9 = tail call signext i8 @tolower(i8 signext %7)
%10 = getelementptr inbounds i8, i8* %4, i64 %8
store i8 %9, i8* %10
%11 = add nuw i64 %8, 1
%12 = getelementptr inbounds i8, i8* %0, i64 %11
%13 = load i8, i8* %12
%14 = icmp eq i8 %13, 0
br i1 %14, label %15, label %6
15: ; preds = %6
%16 = and i64 %11, 4294967295
%17 = getelementptr inbounds i8, i8* %4, i64 %16
store i8 0, i8* %17
ret i8* %4
}