Re: RFA: Do solib address arithmetic with appropriate truncation

[Andrew Cagney <ac131313@cygnus.com>]

> + /* Clear any bits of ADDR that wouldn't fit in a target-format
> +    data pointer.  "Data pointer" here refers to whatever sort of
> +    address the dynamic linker uses to manage its sections.  At the
> +    moment, we don't support shared libraries on any processors where
> +    code and data pointers are different sizes.  */
> + static CORE_ADDR
> + svr4_truncate_ptr (CORE_ADDR addr)
> + {
> +   if (TARGET_PTR_BIT == sizeof (CORE_ADDR) * 8)
> +     /* We don't need to truncate anything, and the bit twiddling below
> +        will fail due to overflow problems.  */
> +     return addr;
> +   else
> +     return addr & (((CORE_ADDR) 1 << TARGET_PTR_BIT) - 1);
> + }


There must be something around that this code can use.  On something 
like a mips, this would be wrong - remember the sign extension problem.

Andrew