Re: C++: Why do we nreverse CLASSTYPE_TAGS

[Gabriel Dos Reis <gdr at integrable-solutions dot net>]

Mark Mitchell <mark at codesourcery dot com> writes:

| On Mon, 2003-03-24 at 11:56, Matt Austern wrote:
| > On Monday, March 24, 2003, at 11:21 AM, Mark Mitchell wrote:
| > 
| > >> OK, I'll experiment with that approach.  What threasold would you put
| > >> for "lots"?
| > >
| > > I dunno.  Probably 10 or so, to start.  With fewer than that, hashing
| > > can't possibly be a win.
| > 
| > How expensive is the hash function?  Unless it's pretty extreme, I'd be 
| > surprised if you needed to get all the way to 10 to get a win.
| 
| Well, it's a hash *function*; you get to make an extra function call.
| 
| As opposed to roughly:
| 
|   for (x = TYPE_FIELDS (t); x; x = TREE_CHAIN (x))
|    if (DECL_NAME (x) == name)
|      break;

Agreed in principle.  But, as I pointed out previously, we don't
actually evaluate the hash function: We just re-use the result of the
initial computation (for interning into the identifier hash table).

Anyway, I'll play with replaing CLASSTYPE_TAGS with a hash-table and
report the result.   

Thanks,

-- Gaby