From: Segher Boessenkool <segher@kernel.crashing.org>
To: Peter Bergner <bergner@linux.ibm.com>
Cc: "Kewen.Lin" <linkw@linux.ibm.com>,
GCC Patches <gcc-patches@gcc.gnu.org>,
David Edelsohn <dje.gcc@gmail.com>
Subject: Re: [PATCH] rs6000/test: Fix bswap64-4.c with has_arch_ppc64 [PR106680]
Date: Wed, 31 Aug 2022 11:05:29 -0500 [thread overview]
Message-ID: <20220831160529.GR25951@gate.crashing.org> (raw)
In-Reply-To: <de65d624-b878-d10e-1044-112f4628a529@linux.ibm.com>
On Wed, Aug 31, 2022 at 10:48:26AM -0500, Peter Bergner wrote:
> On 8/31/22 10:24 AM, Segher Boessenkool wrote:
> > Should *any* explicit command line flag ever be disabled like that?
> > (Not talking about things like -m32 -m64, ...
>
> In a general sense, I'd agree that the answer is no, but we do have
> dependent options like -maltivec and -mvsx, etc., so a -mno-altivec
> better disable any explicit -mvsx earlier on the command line.
Yes, but those two flags are tightly related. -m32/-m64 and -mpowerpc64
are not, code model and instruction set selection are orthogonal.
> Ditto for -msoft-float better disable any -maltivec and -mvsx, etc.
Oh? Why should it disable -maltivec? -mvsx makes a little sense on
one hand, but totally none on the other either.
> It's complicated...and that's a bad thing. :-(
Yes. And most of it is caused by us, instead of being a fact of life.
> > -mpowerpc64 -m32 should always mean the same as -m32 -mpowerpc64, that's
> > the principle of least surprise.
>
> I think I agree with this, since -mpowerpc64 doesn't mean or imply -m64.
> I say "think", because I don't remember the history of why it behaves this
> way and maybe there was a reason we did like this? If there isn't a reason,
> then I'm all for -m32 not overriding -mpowerpc64.
As far as I always knew it does *not* override it, so this seems like
an accident to me, not detected before because everyone always types
-m32 -mpowerpc64 (I know I do, anyway).
I think we should just fix this and see what breaks, if anything?
Segher
next prev parent reply other threads:[~2022-08-31 16:06 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-31 9:33 Kewen.Lin
2022-08-31 14:13 ` Peter Bergner
2022-09-01 8:57 ` Kewen.Lin
2022-09-01 14:57 ` Segher Boessenkool
2022-09-02 0:50 ` Kewen.Lin
2022-09-02 17:36 ` Segher Boessenkool
2022-09-05 2:25 ` Kewen.Lin
2022-08-31 15:24 ` Segher Boessenkool
2022-08-31 15:48 ` Peter Bergner
2022-08-31 16:05 ` Segher Boessenkool [this message]
2022-08-31 17:00 ` Peter Bergner
2022-08-31 19:28 ` Segher Boessenkool
2022-08-31 19:53 ` Peter Bergner
2022-08-31 21:07 ` Segher Boessenkool
2022-08-31 21:38 ` Peter Bergner
2022-08-31 21:49 ` Segher Boessenkool
2022-08-31 22:17 ` Peter Bergner
2022-09-01 9:05 ` Kewen.Lin
2022-09-01 15:04 ` Segher Boessenkool
2022-09-02 0:51 ` Kewen.Lin
2022-09-02 17:44 ` Segher Boessenkool
2022-09-05 2:35 ` Kewen.Lin
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