[M3devel] further reducing cloned headers wrt pthread?

[Jay]

> Hmm, yes, you are right that there is a possible alignment issue. I
> am used to pthread_mutext_t being a simple reference. But surely in C
> the type of the pthread_mutex_t struct would have appropriate
> alignment padding anyway so as to allow allocation using malloc(sizeof
> pthread_mutex_t)? So, it all should just work right?
 
 
I think "the other way around" and same conclusion.
malloc should return something "maximally aligned" so that
 
  pthread_mutex_t* x = (pthread_mutex_t*) malloc(sizeof(pthread_mutex_t));
 
 
works. pthread_mutex_t doesn't need the padding, malloc does, so to speak.
 
 
Just as long as we don't have
 
 
 TYPE Foo = RECORD
   a: pthread_mutex_t; 
   b: pthread_mutex_t; 
   c: pthread_t; 
   d: pthread_t; 
   e: pthread_cond_t; 
   f: pthread_cond_t; 
 END;
 
 
and such, ok.
 
 
malloc on NT returns something with 2 * sizeof(void*) alignment.
I think on Win9x only 4 alignment, thus there is _malloc_aligned for dealing with SSE stuff.
Something like that.
 
 
I didn't realize untraced allocations were basically just malloc but indeed they are.
 
 
I'm still mulling over the possible deoptimizations here.
I'm reluctant to increase heap allocations.
 
 
 
 - Jay