#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 *);
char toupper(char);
char *touppercase(char *string) {
  char tmp[strlen(string)];
  for (int i = 0; i < strlen(string); i++)
    string[i] = toupper(string[i]);
  return string;
}


x86 assembly (clang, -O0):
<touppercase>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %rdi,-0x8(%rbp)
mov    -0x8(%rbp),%rdi
call   1040 <strlen@plt>
mov    %eax,%eax
mov    %rsp,%rcx
mov    %rcx,-0x10(%rbp)
mov    %rax,-0x18(%rbp)
movl   $0x0,-0x1c(%rbp)
mov    -0x1c(%rbp),%eax
mov    %eax,-0x20(%rbp)
mov    -0x8(%rbp),%rdi
call   1040 <strlen@plt>
mov    %eax,%ecx
mov    -0x20(%rbp),%eax
cmp    %ecx,%eax
jge    1191 <touppercase+0x71>
mov    -0x8(%rbp),%rax
movslq -0x1c(%rbp),%rcx
movsbl (%rax,%rcx,1),%edi
call   1030 <toupper@plt>
mov    %al,%dl
mov    -0x8(%rbp),%rax
movslq -0x1c(%rbp),%rcx
mov    %dl,(%rax,%rcx,1)
mov    -0x1c(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x1c(%rbp)
jmp    1149 <touppercase+0x29>
mov    -0x8(%rbp),%rax
mov    -0x10(%rbp),%rcx
mov    %rcx,%rsp
mov    %rbp,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<touppercase>:
push   %r14
push   %rbx
push   %rax
mov    %rdi,%r14
call   1040 <strlen@plt>
mov    %r14,%rdi
call   1040 <strlen@plt>
test   %eax,%eax
jle    1161 <touppercase+0x41>
xor    %ebx,%ebx
nopw   0x0(%rax,%rax,1)
movsbl (%r14,%rbx,1),%edi
call   1030 <toupper@plt>
mov    %al,(%r14,%rbx,1)
add    $0x1,%rbx
mov    %r14,%rdi
call   1040 <strlen@plt>
cltq
cmp    %rax,%rbx
jl     1140 <touppercase+0x20>
mov    %r14,%rax
add    $0x8,%rsp
pop    %rbx
pop    %r14
ret

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

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