#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 toupper(char const);
extern const char *string_toupper(const char *str, char *result) {
  int n = strlen(str);
  int i;
  for (i = 0; i < n; i++) {
    result[i] = toupper(str[i]);
  }
  result[i] = 0;
  return result;
}


x86 assembly (clang, -O0):
<string_toupper>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %rdi,-0x8(%rbp)
mov    %rsi,-0x10(%rbp)
mov    -0x8(%rbp),%rdi
call   1040 <strlen@plt>
mov    %eax,-0x14(%rbp)
movl   $0x0,-0x18(%rbp)
mov    -0x18(%rbp),%eax
cmp    -0x14(%rbp),%eax
jge    117b <string_toupper+0x5b>
mov    -0x8(%rbp),%rax
movslq -0x18(%rbp),%rcx
movsbl (%rax,%rcx,1),%edi
call   1030 <toupper@plt>
mov    %al,%dl
mov    -0x10(%rbp),%rax
movslq -0x18(%rbp),%rcx
mov    %dl,(%rax,%rcx,1)
mov    -0x18(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x18(%rbp)
jmp    1143 <string_toupper+0x23>
mov    -0x10(%rbp),%rax
movslq -0x18(%rbp),%rcx
movb   $0x0,(%rax,%rcx,1)
mov    -0x10(%rbp),%rax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<string_toupper>:
push   %r15
push   %r14
push   %r12
push   %rbx
push   %rax
mov    %rsi,%r14
mov    %rdi,%r12
call   1040 <strlen@plt>
test   %eax,%eax
jle    1159 <string_toupper+0x39>
mov    %eax,%r15d
xor    %ebx,%ebx
nopl   0x0(%rax)
movsbl (%r12,%rbx,1),%edi
call   1030 <toupper@plt>
mov    %al,(%r14,%rbx,1)
add    $0x1,%rbx
cmp    %rbx,%r15
jne    1140 <string_toupper+0x20>
jmp    115c <string_toupper+0x3c>
xor    %r15d,%r15d
movb   $0x0,(%r14,%r15,1)
mov    %r14,%rax
add    $0x8,%rsp
pop    %rbx
pop    %r12
pop    %r14
pop    %r15
ret

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

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