Possible bug in WASM: Pointer math issue when using Emscripten as backend for FreeBasic

I have found some weird issues that lead to code producing the exception "index out of bounds". The minimal code that produces the error is:

```
int arr[14];
int main(){
for (int i=0;i<=5;i++){
*(int*)(((int)(int*)arr + (-i << (2 & 31))) + 52) = i;
}
}

```

This code, that is very similar, seems to work with no problem:
```
int main(){
int arr[14];
for (int i=0;i<=5;i++){
*(int*)(((int)(int*)arr + (-i << (2 & 31))) + 52) = i;
}
}
```

What might cause it?
In case you wonder why I am using such a weird code, instead of a simple "arr[13-i]=i;", the reason is that the code is produced by the C emitter of the FreeBasic compiler (and it works perfectly with the GCC compiler on other platforms). More information is available on the FreeBasic forum, in this [thread](https://www.freebasic.net/forum/viewtopic.php?p=300465#p300465)