Re: [PATCH 6/8] Use std::unordered_map instead of htab_t.

[Pedro Alves <palves at redhat dot com>]

On 05/03/2018 07:41 PM, Keith Seitz wrote:
> This patch simply removes the use of libiberty's hashtab facility in favor
> of C++'s unordered_map.

Do you know whether these hash tables end up with just a few entries, or
many entries?  I hope the open vs closed hashing, different hashing, and
increased memory usage aren't a real concern here.

> -
>  /* See compile-internal.h.  */
>  
>  void
>  compile_instance::insert_symbol_error (const struct symbol *sym,
> -				       const char *text)
> +				       std::string text)

Is this passing by value/copy on purpose?

>  {
> -  struct symbol_error e;
> -  void **slot;
> +  symbol_err_map_t::iterator pos = m_symbol_err_map.find (sym);
>  
> -  if (m_symbol_err_map == NULL)
> -    {
> -      m_symbol_err_map = htab_create_alloc (10,
> -					    hash_symbol_error,
> -					    eq_symbol_error,
> -					    del_symbol_error,
> -					    xcalloc,
> -					    xfree);
> -    }
> -
> -  e.sym = sym;
> -  slot = htab_find_slot (m_symbol_err_map, &e, INSERT);
> -  if (*slot == NULL)
> -    {
> -      struct symbol_error *e = XNEW (struct symbol_error);
> -
> -      e->sym = sym;
> -      e->message = xstrdup (text);
> -      *slot = e;
> -    }
> +  if (pos == m_symbol_err_map.end ())
> +    m_symbol_err_map.insert (std::make_pair (sym, text));

Move 'text' ?

>  }
>  
>  /* See compile-internal.h.  */
> @@ -115,20 +50,13 @@ compile_instance::insert_symbol_error (const struct symbol *sym,
>  void
>  compile_instance::error_symbol_once (const struct symbol *sym)
>  {
> -  struct symbol_error search;
> -  struct symbol_error *err;
> -
> -  if (m_symbol_err_map == NULL)
> -    return;
> -
> -  search.sym = sym;
> -  err = (struct symbol_error *) htab_find (m_symbol_err_map, &search);
> -  if (err == NULL || err->message == NULL)
> +  symbol_err_map_t::iterator pos = m_symbol_err_map.find (sym);
> +  if (pos == m_symbol_err_map.end () || pos->second.length () == 0)
>      return;
>  
> -  gdb::unique_xmalloc_ptr<char> message (err->message);
> -  err->message = NULL;
> -  error (_("%s"), message.get ());
> +  std::string message (pos->second);
> +  pos->second.clear ();

Move pos->second instead of copying?


> +  ::error (_("%s"), message.c_str ());
>  }
>  

Thanks,
Pedro Alves