Re: Feature request: ability to describe x86 register halves as contraints.

[Bill Currie <bcurrie at tssc dot co dot nz>]

Jeffrey A Law wrote:
> Nope -- the constant at the end refers to a word sized object -- on
> the x86 words are 32bits.

Ouch, had to try.

> SUBREGs already have a well defined meaning.  I don't suggest overloading
> another meaning on them.

I didn't think overloading subregs was desirable.

> It's not a question of modes or flags, but of how to represent to the
> compiler via the RTL how to access parts of a register.

I'm not sure what you mean. I'm starting to think that this comment is
related to your comment above about the constant reffering to word sized
objects.  I just had the thought of defining a whole new varian of
subreg, BUT then I realized there's still the problem of what to do with
it (as in getting the compiler to us it at the right times).

Does egcs not support the upper half of ANY register size (<=word, I
know DI upper half is accessable) on any machine?

I'm begginning to get more interested in this idea (I've been thinking
about it off and on for a few years, but I've only recently learned
enough to know what you're talking about).

Bill
-- 
Leave others their otherness