Re: Remove global state from gcc/tracer.c

[David Malcolm <dmalcolm at redhat dot com>]

On Thu, 2013-05-23 at 13:31 -0700, Richard Henderson wrote:
> >  /* The Ith entry is the number of objects on a page or order I.  */
> >  
> > -static unsigned objects_per_page_table[NUM_ORDERS];
> > +DEFINE_STATIC_STATE_ARRAY(unsigned, objects_per_page_table, NUM_ORDERS)
> >  
> >  /* The Ith entry is the size of an object on a page of order I.  */
> >  
> > -static size_t object_size_table[NUM_ORDERS];
> > +DEFINE_STATIC_STATE_ARRAY(size_t, object_size_table, NUM_ORDERS)
> >  
> >  /* The Ith entry is a pair of numbers (mult, shift) such that
> >     ((k * mult) >> shift) mod 2^32 == (k / OBJECT_SIZE(I)) mod 2^32,
> >     for all k evenly divisible by OBJECT_SIZE(I).  */
> >  
> > -static struct
> > +struct inverse_table_def
> >  {
> >    size_t mult;
> >    unsigned int shift;
> > -}
> > -inverse_table[NUM_ORDERS];
> > +};
> > +DEFINE_STATIC_STATE_ARRAY(inverse_table_def, inverse_table, NUM_ORDERS)
> >  
> >  /* A page_entry records the status of an allocation page.  This
> >     structure is dynamically sized to fit the bitmap in_use_p.  */
> > @@ -343,7 +346,7 @@ struct free_object
> >  #endif
> >  
> >  /* The rest of the global variables.  */
> > -static struct globals
> > +struct globals
> >  {
> >    /* The Nth element in this array is a page with objects of size 2^N.
> >       If there are any pages with free objects, they will be at the
> > @@ -457,7 +460,11 @@ static struct globals
> >      /* The overhead for each of the allocation orders.  */
> >      unsigned long long total_overhead_per_order[NUM_ORDERS];
> >    } stats;
> > -} G;
> > +};
> > +
> > +DEFINE_STATIC_STATE(globals, G)
> 
> Be careful here.  Note that all of the arrays that you convert are notionally
> static constants defining the bucket sizes for the algorithm, except we don't
> actually compute them at compile time.  They would be true global data shared
> by all threads.

I know - but when you have a big hammer, sometimes it's easier just to
hit all of the nails, rather than just the ones you need to :)

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