From: Nick Ing-Simmons <nik@tiuk.ti.com>
To: law@cygnus.com
Cc: egcs@cygnus.com,
"Michael P. Hayes" <michaelh@ongaonga.chch.cri.nz>,
meissner@cygnus.com, gcc2@cygnus.com
Subject: Re: base + index register addressing
Date: Mon, 20 Oct 1997 09:43:00 -0000 [thread overview]
Message-ID: <199710201403.PAA26045@tiuk.ti.com> (raw)
In-Reply-To: <15650.877132574@hurl.cygnus.com>
Jeffrey A Law <law@cygnus.com> writes:
> In message < 199710172339.MAA26949@ongaonga.chch.cri.nz >you write:
> > Most of the utility of the patch occurs when an incoming function
> > argument is in a hard base (or possibly index) register.
>Yup. I'm all too aware of losing base vs index distinctions
>when hard argument registers.
>
>You see, on the PA, it's absolutely critical that we be able to
>distinguish the base from the index -- if you reverse them in a
>memory reference it will fail at runtime. Furthermore, any
>general register can be a base or index. Thus we can't use a
>set of registers to know which is the base and which is the index.
On some of TI's DSPs index/base are very important as well.
This is almost the inverse of above case - sets of registers are vital !
Here to use a register as an index its hard-register number has to be
"related" to the hard register number of the base.
Current GCC register allocation just cannot handle this, so I have
"given up" (and just lurk here).
next prev parent reply other threads:[~1997-10-20 9:43 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
1997-10-17 12:53 meissner
1997-10-17 13:57 ` Jeffrey A Law
1997-10-17 20:51 ` Michael P. Hayes
1997-10-17 21:40 ` Jeffrey A Law
1997-10-20 9:43 ` Nick Ing-Simmons [this message]
1997-10-20 18:12 ` Joern Rennecke
1997-10-21 8:49 ` Nick Ing-Simmons
1997-10-21 9:25 ` John Carr
[not found] <199710170919.WAA23619@ongaonga.chch.cri.nz>
1997-10-17 13:57 ` Jeffrey A Law
-- strict thread matches above, loose matches on Subject: below --
1997-10-17 12:53 meissner
1997-10-17 13:57 ` Jeffrey A Law
1997-10-17 20:51 ` Richard Henderson
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