Re: [Haskell-cafe] compressed pointers?

ketil:

One of the downsides of a 64-bit environment is the increased size of pointers. This means that the cost of a String increases from something like 12 bytes per char to something like 24.

I notice BEA uses something called "compressed pointers" to get the 64-bit (more registers, etc) benefits without paying the (cache-thrashing) cost.

http://e-docs.bea.com/jrockit/releases/5026x/relnotes/relnotes.html#wp107976...

Something for GHC?

One small upside (performance wise), is that the bottom 3 bits of the pointer are now used to encode the constructor on 64 bits, so 'case' gets a good percent cheaper. -- Don