Re: [Committed] Use special-purpose hash table to speed up walk_tree

[Richard Henderson <rth at redhat dot com>]

On Sat, Oct 16, 2004 at 06:37:12AM -0400, Jakub Jelinek wrote:
> +   choice for A is the integer part of (ULONG_MAX + 1.0) / phi, where phi
> +   is the golden ratio.

Any reason not to use the computation actually described here?

Otherwise, the ifdef one's fine if you use HOST_BITS_PER_LONG
to choose one of the alternatives exactly:

#if HOST_BITS_PER_LONG == 32
  const unsigned long A = 0x9e3779b9u;
#elif HOST_BITS_PER_LONG == 64
  const unsigned long A = 0x9e3779b97f4a7c16ul;
#endif

Which will handily not compile if we ever find something else.


r~