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Re: PATCH: PA PIC symbolic memory fix PART 2
- To: "John David Anglin" <dave at hiauly1 dot hia dot nrc dot ca>
- Subject: Re: PATCH: PA PIC symbolic memory fix PART 2
- From: Jeffrey A Law <law at redhat dot com>
- Date: Tue, 20 Feb 2001 22:38:02 -0700
- cc: gcc-patches at gcc dot gnu dot org
- Reply-To: law at redhat dot com
In message <200102192124.QAA19685@hiauly1.hia.nrc.ca>you write:
> The enclosed patch changes update_equiv_regs to not add REG_EQUIV notes
> I can hear Jeff saying that the REG_EQUIV notes are valid and removing
> them is just fixing a symptom of the problem! However, even if they
> are valid, no registers are saved by substituting the MEMs for long
> PIC references because the register used to construct the LO_SUM must
> be kept alive or saved in the frame. It is better to keep the register
> with the address result alive, and let the intermediate temporary register
Actually, it can easily cut down the number of registers.
Instead of extending the lifetime of the destination of the HIGH, you
simply resynthesize the HIGH when you need it. It's just an addil
instruction, which is way cheap.
> This patch is simple and should have limited side effects. It allows
> me to do a full bootstrap check in PIC mode, something that has not
> been possible previously for hppa1.1-hp-hpux10.20.
> Please review?
> J. David Anglin firstname.lastname@example.org
> National Research Council of Canada (613) 990-0752 (FAX: 952-6
> 2001-02-17 John David Anglin <email@example.com>
> * local-alloc.c (update_equiv_regs): Only add REG_EQUIV notes to MEMs
> that are not unstable.
Let's just hold off for a little while so that I can think this through
One of the problems (in my mind) is we've got too many patches flying by
all to fix the same set of problems or symptoms of those problems.