#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 */
scalar_t__ isalpha(int);
char tolower(int);
char *mt_tolower(char *p) {
  char *q;
  for (q = p; *q != '\0'; ++q) {
    if (isalpha((int)*q))
      *q = tolower((int)*q);
  }
  return (p);
}


x86 assembly (clang, -O0):
<mt_tolower>:
push   %rbp
mov    %rsp,%rbp
sub    $0x10,%rsp
mov    %rdi,-0x8(%rbp)
mov    -0x8(%rbp),%rax
mov    %rax,-0x10(%rbp)
mov    -0x10(%rbp),%rax
movsbl (%rax),%eax
cmp    $0x0,%eax
je     1184 <mt_tolower+0x64>
mov    -0x10(%rbp),%rax
movsbl (%rax),%edi
call   1040 <isalpha@plt>
cmp    $0x0,%rax
je     116e <mt_tolower+0x4e>
mov    -0x10(%rbp),%rax
movsbl (%rax),%edi
call   1030 <tolower@plt>
mov    %al,%cl
mov    -0x10(%rbp),%rax
mov    %cl,(%rax)
jmp    1173 <mt_tolower+0x53>
mov    -0x10(%rbp),%rax
add    $0x1,%rax
mov    %rax,-0x10(%rbp)
jmp    1134 <mt_tolower+0x14>
mov    -0x8(%rbp),%rax
add    $0x10,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<mt_tolower>:
push   %r14
push   %rbx
push   %rax
mov    %rdi,%r14
mov    (%rdi),%al
test   %al,%al
je     1165 <mt_tolower+0x45>
mov    %r14,%rbx
jmp    114c <mt_tolower+0x2c>
cs nopw 0x0(%rax,%rax,1)
nopl   0x0(%rax)
movzbl 0x1(%rbx),%eax
add    $0x1,%rbx
test   %al,%al
je     1165 <mt_tolower+0x45>
movsbl %al,%edi
call   1040 <isalpha@plt>
test   %rax,%rax
je     1140 <mt_tolower+0x20>
movsbl (%rbx),%edi
call   1030 <tolower@plt>
mov    %al,(%rbx)
jmp    1140 <mt_tolower+0x20>
mov    %r14,%rax
add    $0x8,%rsp
pop    %rbx
pop    %r14
ret

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

LLVM IR (-O2):
define i8* @mt_tolower(i8* returned %0) {
%2 = load i8, i8* %0
%3 = icmp eq i8 %2, 0
br i1 %3, label %18, label %4
4: ; preds = %1, %14
%5 = phi i8 [ %16, %14 ], [ %2, %1 ]
%6 = phi i8* [ %15, %14 ], [ %0, %1 ]
%7 = sext i8 %5 to i32
%8 = tail call i64 @isalpha(i32 %7)
%9 = icmp eq i64 %8, 0
br i1 %9, label %14, label %10
10: ; preds = %4
%11 = load i8, i8* %6
%12 = sext i8 %11 to i32
%13 = tail call signext i8 @tolower(i32 %12)
store i8 %13, i8* %6
br label %14
14: ; preds = %4, %10
%15 = getelementptr inbounds i8, i8* %6, i64 1
%16 = load i8, i8* %15
%17 = icmp eq i8 %16, 0
br i1 %17, label %18, label %4
18: ; preds = %14, %1
ret i8* %0
}