From: Mike Frysinger <vapier@gentoo.org>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: libc-alpha@sourceware.org, GCC Development <gcc@gcc.gnu.org>,
LKML <linux-kernel@vger.kernel.org>,
x32-abi@googlegroups.com
Subject: Re: X32 psABI status update
Date: Mon, 21 Mar 2011 05:53:00 -0000 [thread overview]
Message-ID: <201103210153.10145.vapier@gentoo.org> (raw)
In-Reply-To: <AANLkTikSJDGEWCqazvAKHUC8_MoOP-+vyFOjyCmrA9dL@mail.gmail.com>
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On Monday, March 21, 2011 01:35:35 H.J. Lu wrote:
> On Sun, Mar 20, 2011 at 10:08 PM, Mike Frysinger wrote:
> > On Thursday, March 17, 2011 01:21:16 H.J. Lu wrote:
> >> On Wed, Mar 16, 2011 at 7:57 PM, Mike Frysinger wrote:
> >> > in looking at the gcc files, it doesnt seem like there's any defines
> >> > setup to declare x32 directly. instead, you'd have to do something
> >> > like: #ifdef __x86_64__
> >> > # if __SIZEOF_LONG__ == 8
> >> > /* x86_64 */
> >> > # else
> >> > /* x32 */
> >> > # endif
> >> > #endif
> >> >
> >> > any plans on adding an __x32__ (or whatever) cpp symbol to keep people
> >> > from coming up with their own special/broken crap ? or are there some
> >> > already that i'm not seeing ?
> >>
> >> The idea is in most cases, you only need to check __x86_64__ since x32
> >> and x86-64 are very close. In some cases, x32 is very different from
> >> x86_64, like assembly codes on long and pointer, you can check
> >> __x86_64__ and __LP64__. In glibc, I used a different approach by using
> >> macros REG_RAX, .., MOV_LP, ADD_LP, SUB_LP and CMP_LP in assembly
> >> codes.
> >
> > while i agree with you in general that this is how people should be doing
> > things, in practice i often see people fishing around. education only
> > goes so far, so if there was an __x32__ define, i feel like people are
> > more likely to get it right than wrong.
> >
> > i dont have any use cases off the top of my head, but i wouldnt be
> > surprised if the heavy inline assembly people (like the multimedia peeps
> > e.g. libav) approached it this way. rather than google for
> > documentation, look at the cpp output between -m64 and -mx32 and see
> > what sticks out. "__x32__" would certainly do that.
>
> My point is __x86_64__ version should work for both 64bit and x32. There
> should no need for a separate x32 version.
yes, and my point is that people often reach for cpp defines rather than
figure out how to do it right.
i'm not saying that __x32__ should be defined in place of __x86_64__, just
that when -mx32 is used, __x32__ is additionally defined. simply as an
example, what i'm referring to could be accomplished by adding this to the
*cpp specs:
%{mx32:-D__x32__=1}
-mike
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next prev parent reply other threads:[~2011-03-21 5:53 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-05 19:08 H.J. Lu
2011-03-06 17:29 ` H.J. Lu
2011-03-07 21:33 ` Mike Frysinger
2011-03-16 4:17 ` H.J. Lu
2011-03-16 4:30 ` Mike Frysinger
2011-03-16 4:51 ` H.J. Lu
2011-03-16 5:24 ` Mike Frysinger
2011-03-16 12:40 ` H.J. Lu
2011-03-17 2:57 ` Mike Frysinger
2011-03-17 5:21 ` H.J. Lu
2011-03-17 5:45 ` Mike Frysinger
2011-03-17 14:43 ` H.J. Lu
2011-03-17 17:38 ` Richard Henderson
2011-03-21 5:09 ` Mike Frysinger
2011-03-21 5:35 ` H.J. Lu
2011-03-21 5:53 ` Mike Frysinger [this message]
2011-03-21 6:55 ` H.J. Lu
2011-03-21 8:20 ` Michael Matz
2011-03-21 10:52 ` H.J. Lu
[not found] ` <201103160124.42939.vapier__14164.6524928094$1300277836$gmane$org@gentoo.org>
2011-03-16 12:40 ` Andreas Schwab
2011-03-16 4:19 ` H.J. Lu
-- strict thread matches above, loose matches on Subject: below --
2011-02-17 11:04 x32 " H.J. Lu
2011-02-19 20:57 ` H.J. Lu
2011-02-19 22:01 ` H.J. Lu
[not found] ` <AANLkTikkpK9ouXckHaVzwXe+p_Cz2hVH5T7xOoQL7OSE@mail.gmail.com>
2011-02-19 22:52 ` H.J. Lu
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