From: Alan Modra <amodra@gmail.com>
To: Peter Bergner <bergner@linux.ibm.com>
Cc: GCC <gcc@gcc.gnu.org>
Subject: Re: Question regarding constraint usage within inline asm
Date: Thu, 21 Feb 2019 03:40:00 -0000 [thread overview]
Message-ID: <20190221033958.GE23427@bubble.grove.modra.org> (raw)
In-Reply-To: <e08e8592-e6bf-b6bd-890a-debaf58a70eb@linux.ibm.com>
On Wed, Feb 20, 2019 at 08:57:52PM -0600, Peter Bergner wrote:
> On 2/20/19 4:19 PM, Alan Modra wrote:
> > I forgot to say, gcc-6, gcc-7 and gcc-8 handle your original testcase
> > with the register asm just fine.
>
> Yes, because they don't have my IRA and LRA patches that exposed this
> problem. I would say they were buggy for not complaining and silently
> spilling a hard register in the case where we used asm reg("...").
I don't follow your reasoning. It seems to me that giving some
variable a register asm doesn't mean that the value of that variable
can't appear in some other register. An obvious example is when
passing that variable to a function.
So why shouldn't a hard reg be reloaded in order to satisfy
incompatible constraints?
--
Alan Modra
Australia Development Lab, IBM
next prev parent reply other threads:[~2019-02-21 3:40 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-18 19:14 Peter Bergner
2019-02-20 3:10 ` Alan Modra
2019-02-20 16:08 ` Peter Bergner
2019-02-20 19:24 ` Segher Boessenkool
2019-02-20 22:04 ` Alan Modra
2019-02-20 22:19 ` Alan Modra
2019-02-21 2:57 ` Peter Bergner
2019-02-21 3:40 ` Alan Modra [this message]
2019-02-21 23:16 ` Peter Bergner
2019-02-22 1:08 ` Segher Boessenkool
2019-02-25 18:32 ` Michael Matz
2019-02-28 4:16 ` Segher Boessenkool
2019-02-28 13:01 ` Michael Matz
2019-02-21 3:03 ` Peter Bergner
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