#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 */
unsigned int strlen(char *);
void StrToLower(char *s) {
  unsigned int i;
  for (i = 0; i < strlen(s); i++) {
    if (s[i] >= 'A' && s[i] <= 'Z')
      s[i] += 'a' - 'A';
  }
}


x86 assembly (clang, -O0):
<StrToLower>:
push   %rbp
mov    %rsp,%rbp
sub    $0x10,%rsp
mov    %rdi,-0x8(%rbp)
movl   $0x0,-0xc(%rbp)
mov    -0xc(%rbp),%eax
mov    %eax,-0x10(%rbp)
mov    -0x8(%rbp),%rdi
call   1030 <strlen@plt>
mov    %eax,%ecx
mov    -0x10(%rbp),%eax
cmp    %ecx,%eax
jae    118b <StrToLower+0x7b>
mov    -0x8(%rbp),%rax
mov    -0xc(%rbp),%ecx
movsbl (%rax,%rcx,1),%eax
cmp    $0x41,%eax
jl     1178 <StrToLower+0x68>
mov    -0x8(%rbp),%rax
mov    -0xc(%rbp),%ecx
movsbl (%rax,%rcx,1),%eax
cmp    $0x5a,%eax
jg     1178 <StrToLower+0x68>
mov    -0x8(%rbp),%rax
mov    -0xc(%rbp),%ecx
movsbl (%rax,%rcx,1),%edx
add    $0x20,%edx
mov    %dl,(%rax,%rcx,1)
jmp    117d <StrToLower+0x6d>
mov    -0xc(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0xc(%rbp)
jmp    1123 <StrToLower+0x13>
add    $0x10,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<StrToLower>:
push   %r14
push   %rbx
push   %rax
mov    %rdi,%r14
call   1030 <strlen@plt>
test   %eax,%eax
je     1158 <StrToLower+0x48>
xor    %ebx,%ebx
jmp    1143 <StrToLower+0x33>
cs nopw 0x0(%rax,%rax,1)
xchg   %ax,%ax
add    $0x1,%rbx
mov    %r14,%rdi
call   1030 <strlen@plt>
mov    %eax,%eax
cmp    %rax,%rbx
jae    1158 <StrToLower+0x48>
movzbl (%r14,%rbx,1),%eax
lea    -0x41(%rax),%ecx
cmp    $0x19,%cl
ja     1130 <StrToLower+0x20>
add    $0x20,%al
mov    %al,(%r14,%rbx,1)
jmp    1130 <StrToLower+0x20>
add    $0x8,%rsp
pop    %rbx
pop    %r14
ret

LLVM IR (-O0):
define void @StrToLower(i8* %0) {
%2 = alloca i8*
%3 = alloca i32
store i8* %0, i8** %2
store i32 0, i32* %3
br label %4
4: ; preds = %35, %1
%5 = load i32, i32* %3
%6 = load i8*, i8** %2
%7 = call i32 @strlen(i8* %6)
%8 = icmp ult i32 %5, %7
br i1 %8, label %9, label %38
9: ; preds = %4
%10 = load i8*, i8** %2
%11 = load i32, i32* %3
%12 = zext i32 %11 to i64
%13 = getelementptr inbounds i8, i8* %10, i64 %12
%14 = load i8, i8* %13
%15 = sext i8 %14 to i32
%16 = icmp sge i32 %15, 65
br i1 %16, label %17, label %34
17: ; preds = %9
%18 = load i8*, i8** %2
%19 = load i32, i32* %3
%20 = zext i32 %19 to i64
%21 = getelementptr inbounds i8, i8* %18, i64 %20
%22 = load i8, i8* %21
%23 = sext i8 %22 to i32
%24 = icmp sle i32 %23, 90
br i1 %24, label %25, label %34
25: ; preds = %17
%26 = load i8*, i8** %2
%27 = load i32, i32* %3
%28 = zext i32 %27 to i64
%29 = getelementptr inbounds i8, i8* %26, i64 %28
%30 = load i8, i8* %29
%31 = sext i8 %30 to i32
%32 = add nsw i32 %31, 32
%33 = trunc i32 %32 to i8
store i8 %33, i8* %29
br label %34
34: ; preds = %25, %17, %9
br label %35
35: ; preds = %34
%36 = load i32, i32* %3
%37 = add i32 %36, 1
store i32 %37, i32* %3
br label %4
38: ; preds = %4
ret void
}

LLVM IR (-O2):
define void @StrToLower(i8* %0) {
%2 = tail call i32 @strlen(i8* %0)
%3 = icmp eq i32 %2, 0
br i1 %3, label %17, label %4
4: ; preds = %1, %12
%5 = phi i64 [ %13, %12 ], [ 0, %1 ]
%6 = getelementptr inbounds i8, i8* %0, i64 %5
%7 = load i8, i8* %6
%8 = add i8 %7, -65
%9 = icmp ult i8 %8, 26
br i1 %9, label %10, label %12
10: ; preds = %4
%11 = add nuw nsw i8 %7, 32
store i8 %11, i8* %6
br label %12
12: ; preds = %4, %10
%13 = add nuw nsw i64 %5, 1
%14 = tail call i32 @strlen(i8* %0)
%15 = zext i32 %14 to i64
%16 = icmp ult i64 %13, %15
br i1 %16, label %4, label %17
17: ; preds = %12, %1
ret void
}