Version française
Home     About     Download     Resources     Contact us    

This site is updated infrequently. For up-to-date information, please visit the new OCaml website at

Browse thread
32- and 64-bit performance
[ Home ] [ Index: by date | by threads ]
[ Search: ]

[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
Date: 2005-04-02 (20:50)
From: David Brown <caml@d...>
Subject: Re: [Caml-list] Re: 32- and 64-bit performance
On Sat, 02 Apr 2005 15:23:21 -0500, Stefan Monnier  
<> wrote:

> Under Alpha they called it "taso".  Mostly used for compatibility with  
> apps
> that were assuming the size of ptrs is the same as the size of int: it  
> just
> made the C library use only the bottom 4GB of the address space such that
> the compiler could use only 32bit to store pointer values.

The default mode in gcc for amd64 is almost this (-mcmodel=small).  It  
assumes pointers live in the lower 2GB of address space, but 'sizeof (void  
*)' is still 8.  I'm not sure why the small model doesn't use 32-bit  

The -mcmodel=medium model does 64-bit operations on pointers, but the code  
must still live in the lower 2GB of address space.

The -mcmodel=large isn't yet implemented.