Re: [rfc] Add some more floatformat types ....

[Kevin Buettner <kevinb at cygnus dot com>]

On Aug 17, 12:12pm, Andrew Cagney wrote:

>  > The IA-64, for instance, has an 82 bit floating-point register.  That
>  >    register is always represented in memory as 128 bits. 
> Consequently, my
>  >    proposal includes ia64_ext128 and not ia64_ext82.
>  >
>  > So we only need a single floatformat_ia64_ext.  Why not keep the
>  > floatformat_ia64_ext that we already have in ia64-tdep.c and move it
>  > to ../libiberty/floatformat.c?
> 
> Dam!  You spotted my cunning plan :-)  That is one of the next steps. 
> In the light of the exchange above, a double check on this one is in order.
> 
> Kevin, am I correct in saying that the ia64 reads/writes 16 bytes when 
> loading/storing an ia64_ext?

Yes.  But I'd rephrase it as...  The IA-64 reads/writes 16 bytes when
loading/storing the 82-bit floating point register format.

The fly in the ointment is that the IA-64 also has a quad precision
real type whose width is 128 bits (1 bit sign, 15 bit exponent,
112 bit significand).

> Mark, this meaning that the ia64_ext should have a size of 128 and not 
> 82 as it currently does in ia64-tdep.c?

In order to avoid confusion, I think it might be better for the name
to reflect the actual number of bits used in the memory container as
well as the width of the memory container.  Maybe something along the
lines of ia64_reg82_mem128?  Perhaps something similar could also be
done of x86?