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From: Segher Boessenkool <segher@kernel.crashing.org>
To: Vladimir Makarov <vmakarov@redhat.com>
Cc: Richard Biener <richard.guenther@gmail.com>,
	gcc@gcc.gnu.org,
	       John Darrington <john@darrington.wattle.id.au>,
	       Jeff Law <law@redhat.com>,
	Paul Koning <paulkoning@comcast.net>
Subject: Re: Indirect memory addresses vs. lra
Date: Thu, 15 Aug 2019 21:22:00 -0000	[thread overview]
Message-ID: <20190815212245.GR31406@gate.crashing.org> (raw)
In-Reply-To: <61d0afa8-2253-1a52-9081-42983f48ada7@redhat.com>

On Thu, Aug 15, 2019 at 02:30:19PM -0400, Vladimir Makarov wrote:
> >Couldn't we spill the frame pointer? Basically we should be able to 
> >compute the first address into a reg, spill that, do the second (both 
> >could require the frame pointer), spill the frame pointer, reload the 
> >first computed address from the stack, execute the insn and then reload 
> >the frame pointer.
> >
> >Maybe the frame pointer can also be implemented 'virually' in an index 
> >register that you keep updated so that sp + reg
> >Is the FP. Or frame accesses can use a
> >Stack slot as FP and the indirect memory
> >Addressing... (is there an indirect lea?)
> >
> Yes, it could be a solution.  It just needs some target maintainer 
> creativity.  There are a lot of things (tricks) can be done in 
> machine-dependent code which would not require RA changes.

You can even go as far as not having the hard frame pointer be a machine
register at all.  In RTL it will still be a reg, but that doesn't mean
the machine code you emit should be like that; you can use a special
fixed memory location for it, for example.


Segher

  reply	other threads:[~2019-08-15 21:22 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-04 19:18 John Darrington
2019-08-08 16:25 ` Vladimir Makarov
2019-08-08 16:44   ` Paul Koning
2019-08-08 17:21     ` Segher Boessenkool
2019-08-08 17:25       ` Paul Koning
2019-08-08 19:09         ` Segher Boessenkool
2019-08-08 17:30       ` Paul Koning
2019-08-08 19:19         ` Segher Boessenkool
2019-08-08 19:57           ` Jeff Law
2019-08-09  8:14             ` John Darrington
2019-08-09 14:17               ` Segher Boessenkool
2019-08-09 14:23                 ` Paul Koning
2019-08-10  6:10                 ` John Darrington
2019-08-10 16:15                   ` Segher Boessenkool
2019-08-09 16:07               ` Jeff Law
2019-08-09 17:34               ` Vladimir Makarov
2019-08-10  6:06                 ` John Darrington
2019-08-10 16:12                   ` Segher Boessenkool
2019-08-12  6:47                     ` John Darrington
2019-08-12  8:40                       ` Segher Boessenkool
2019-08-12 13:35                   ` Vladimir Makarov
2019-08-15 16:29                   ` Vladimir Makarov
2019-08-15 16:38                     ` Richard Biener
2019-08-15 17:41                       ` John Darrington
2019-08-15 18:30                       ` Vladimir Makarov
2019-08-15 21:22                         ` Segher Boessenkool [this message]
2019-08-15 17:36                     ` John Darrington
2019-08-15 18:23                       ` Vladimir Makarov
2019-08-16 11:24                         ` Special Memory Constraint [was Re: Indirect memory addresses vs. lra] John Darrington
2019-08-16 14:50                           ` Vladimir Makarov
2019-08-19  7:36                             ` John Darrington
2019-08-19 13:14                               ` Vladimir Makarov
2019-08-19 15:07                                 ` Segher Boessenkool
2019-08-19 18:06                                   ` John Darrington
2019-08-20  6:56                                     ` Richard Biener
2019-08-20  7:07                                       ` John Darrington
2019-08-20  7:30                                         ` Richard Biener
2019-08-08 18:46     ` Indirect memory addresses vs. lra Vladimir Makarov

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