From: Jeffrey A Law <law@cygnus.com>
To: Richard Henderson <rth@cygnus.com>
Cc: egcs@cygnus.com, gcc2@cygnus.com
Subject: Re: double_reg_address_ok
Date: Mon, 06 Apr 1998 17:35:00 -0000 [thread overview]
Message-ID: <23077.891885299@hurl.cygnus.com> (raw)
In-Reply-To: <19980405034830.11235@dot.cygnus.com>
In message < 19980405034830.11235@dot.cygnus.com >you write:
> This is truely ancient history, but why
>
> Wed Sep 6 00:39:35 1989 Richard Stallman (rms at sugar-bombs.ai.mit.edu)
>
> * reload1.c (reload): When setting double_reg_address_ok,
> require it to be offsettable.
>
> There does not currently appear to be anything about the code that
> is predicated on double_reg_address_ok that seems to require that
> the result be offsettable.
>
> The fact that we currently require this means that on Sparc, reloading
> large offsets off of fp takes an extra instruction and register.
Well, it looks like this was a sparc related change:
* reload1.c (reload): When setting double_reg_address_ok,
require it to be offsettable.
* out-sparc.c (output_fp_move_double): Now safe to use std
for all reg+reg addresses.
I presume sparc.md at the time had a pattern which accepted any old
memory address. One might argue it should have accepted only offsettable
addresses or that output_fp_move_double should handle a memory address
that is not offsettable.
The PA handles this case by incrementing a register in the address
before the memref, then decrementing it afterwards.
jeff
next prev parent reply other threads:[~1998-04-06 17:35 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-04-05 5:39 double_reg_address_ok Richard Henderson
1998-04-05 17:27 ` double_reg_address_ok Richard Henderson
1998-04-06 17:35 ` Jeffrey A Law [this message]
1998-04-08 2:13 ` double_reg_address_ok Jim Wilson
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