64 bit ints

[Gordon Cross]

In article <6264 at june.cs.washington.edu>, david at june.cs.washington.edu (David Callahan) writes:
> 
> Suppose I am designing a C compiler for a machine with 64bit
> words. "Char" should be 8bits of course and "long int" 64 since
> pointers will be.
> 
> How long should an "int" be (32 or 64)? 
> How about a "short int" (16/32)?
> How is this decision altered if partial word accesses 
> are more expensive than full word accesses?

As I recall the proposed ANSI standard states that the type "int" should be
the size which is most "natural" or efficient on the target machine.  This
has been 32-bits on all 64-bit machines I've seen.  If your machine has a
64-bit word size and a halfword (32 bits) access is more expensive then perhaps
a 64-bit "int" is appropiate.  Seems like that if your machine has support
for 8, 16, 32, AND 64 bit integers then your only choice would have to be

     char   8 bits
     short 16 bits
     int   32 bits
     long  64 bits

unless someone wants to introduce "short short int" and/or "long long int"!!!!


Gordon Cross
Intergraph Corp.  Huntsville, AL