Re: [f-cpu] latest gcc & immediate addressing [Was: BOUNCE f-cpu@seul.org:...] (fwd)

[Michael Riepe <michael@stud.uni-hannover.de>]

On Wed, Jan 08, 2003 at 12:17:46PM +0100, devik wrote:
[...]
> > > good point - it is another thing I didn't find in manual. So
> > > that f-cpu needs natural align on all data ?
> >
> > Yes, up to 8 bytes at least. It's not clear yet whether machines with
> > larger registers will have even stricter alignment constraints. For
> > the moment, we should concentrate on the 64-bit version.
> 
> "at least" ? I suppose 32bit in needs to be "naturaly"
> (32bit) aligned, ok ?

Of course. But it's not yet clear what happens with data items > 64 bits.
They may have to be naturally aligned, or may need only 8-byte alignment.
That depends very much on the LSU which isn't ready yet.

> > > :) They are under developement still but the really describe what
> > > loadcons does !!
> > > They should be also able to translate code:
> > > a = b & 0xffffffff0000ffff | 0x45330000;
> > > to single loadcons.1.
> >
> > Isn't that a rather rare case? It only seems suitable for access to
> > certain bitfields.
> 
> yes it is of course. But if you want compined to be able to use and
> split them you need to descrtibe their behaviour. And the description
> I used is perfectly valid.

Except that it lacks a description of loadcons.2 and loadcons.3 :)

[...]
> > The documentation seemed to be pretty clear that a LABEL_REF always
> > refers to code, while a SYMBOL_REF refers to data. It even mentions
> > that:
> >
> > 	"The reason for using a distinct expression type for code label
> > 	references is so that jump optimization can distinguish them."
> 
> ok here is part of generated switch stat:
> (insn 101 99 102 (set (reg:DI 83)
>         (label_ref:DI 107)) -1 (nil)
>     (expr_list:REG_EQUAL (label_ref:DI 107)
>         (nil)))
> 
> (label_ref:DI 107) is label of jump table. Here we need loadaddrid
> even if it is not clear.

Heck. gcc is a piece of shit, isn't it?

-- 
 Michael "Tired" Riepe <Michael.Riepe@stud.uni-hannover.de>
 "All I wanna do is have a little fun before I die"
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