int main() {
  int strstart = 0;
  int hash_head = 2;
  int prev_length = 5;
  int ins_h = 1;
  int prev[32 << 10] = {0};
  int head[32 << 10] = {0};
  int window[1024] = {0};
  do {
    strstart++;
    ((ins_h = (((ins_h) << ((15 + 3 - 1) / 3)) ^ (window[(strstart) + 3 - 1])) &
              0xFFFF),
     prev[(strstart)&0xFFFF] = hash_head = head[ins_h],
     head[ins_h] = (strstart));
  } while (--prev_length != 0);
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x41020,%rsp
movl   $0x0,-0x4(%rbp)
movl   $0x0,-0x8(%rbp)
movl   $0x2,-0xc(%rbp)
movl   $0x5,-0x10(%rbp)
movl   $0x1,-0x14(%rbp)
lea    -0x20020(%rbp),%rdi
xor    %esi,%esi
mov    $0x20000,%edx
call   1030 <memset@plt>
lea    -0x40020(%rbp),%rdi
xor    %esi,%esi
mov    $0x20000,%edx
call   1030 <memset@plt>
lea    -0x41020(%rbp),%rdi
xor    %esi,%esi
mov    $0x1000,%edx
call   1030 <memset@plt>
mov    -0x8(%rbp),%eax
add    $0x1,%eax
mov    %eax,-0x8(%rbp)
mov    -0x14(%rbp),%eax
shl    $0x5,%eax
mov    -0x8(%rbp),%ecx
add    $0x3,%ecx
sub    $0x1,%ecx
movslq %ecx,%rcx
xor    -0x41020(%rbp,%rcx,4),%eax
and    $0xffff,%eax
mov    %eax,-0x14(%rbp)
movslq -0x14(%rbp),%rax
mov    -0x40020(%rbp,%rax,4),%ecx
mov    %ecx,-0xc(%rbp)
mov    -0x8(%rbp),%eax
and    $0xffff,%eax
cltq
mov    %ecx,-0x20020(%rbp,%rax,4)
mov    -0x8(%rbp),%ecx
movslq -0x14(%rbp),%rax
mov    %ecx,-0x40020(%rbp,%rax,4)
mov    -0x10(%rbp),%eax
add    $0xffffffff,%eax
mov    %eax,-0x10(%rbp)
cmp    $0x0,%eax
jne    1177 <main+0x67>
mov    -0x4(%rbp),%eax
add    $0x41020,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<main>:
xor    %eax,%eax
ret

LLVM IR (-O0):
define i32 @main() {
%1 = alloca i32
%2 = alloca i32
%3 = alloca i32
%4 = alloca i32
%5 = alloca i32
%6 = alloca [32768 x i32]
%7 = alloca [32768 x i32]
%8 = alloca [1024 x i32]
store i32 0, i32* %1
store i32 0, i32* %2
store i32 2, i32* %3
store i32 5, i32* %4
store i32 1, i32* %5
%9 = bitcast [32768 x i32]* %6 to i8*
%10 = bitcast [32768 x i32]* %7 to i8*
%11 = bitcast [1024 x i32]* %8 to i8*
br label %12
12: ; preds = %37, %0
%13 = load i32, i32* %2
%14 = add nsw i32 %13, 1
store i32 %14, i32* %2
%15 = load i32, i32* %5
%16 = shl i32 %15, 5
%17 = load i32, i32* %2
%18 = add nsw i32 %17, 3
%19 = sub nsw i32 %18, 1
%20 = sext i32 %19 to i64
%21 = getelementptr inbounds [1024 x i32], [1024 x i32]* %8, i64 0, i64 %20
%22 = load i32, i32* %21
%23 = xor i32 %16, %22
%24 = and i32 %23, 65535
store i32 %24, i32* %5
%25 = load i32, i32* %5
%26 = sext i32 %25 to i64
%27 = getelementptr inbounds [32768 x i32], [32768 x i32]* %7, i64 0, i64 %26
%28 = load i32, i32* %27
store i32 %28, i32* %3
%29 = load i32, i32* %2
%30 = and i32 %29, 65535
%31 = sext i32 %30 to i64
%32 = getelementptr inbounds [32768 x i32], [32768 x i32]* %6, i64 0, i64 %31
store i32 %28, i32* %32
%33 = load i32, i32* %2
%34 = load i32, i32* %5
%35 = sext i32 %34 to i64
%36 = getelementptr inbounds [32768 x i32], [32768 x i32]* %7, i64 0, i64 %35
store i32 %33, i32* %36
br label %37
37: ; preds = %12
%38 = load i32, i32* %4
%39 = add nsw i32 %38, -1
store i32 %39, i32* %4
%40 = icmp ne i32 %39, 0
br i1 %40, label %12, label %41
41: ; preds = %37
%42 = load i32, i32* %1
ret i32 %42
}

LLVM IR (-O2):
define i32 @main() {
ret i32 0
}