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Re: [PATCH] C++ ABI fix - bitfield layout on IA-32 (take 2)

From: Mark Mitchell <mark at codesourcery dot com>
To: Jakub Jelinek <jakub at redhat dot com>, "rth at redhat dot com" <rth at redhat dot com>, "jh at suse dot cz" <jh at suse dot cz>
Cc: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
Date: Mon, 05 Aug 2002 08:06:27 -0700
Subject: Re: [PATCH] C++ ABI fix - bitfield layout on IA-32 (take 2)

--On Monday, August 05, 2002 03:58:04 PM +0200 Jakub Jelinek <jakub@redhat.com> wrote:

On Mon, Aug 05, 2002 at 01:37:54PM +0200, Jakub Jelinek wrote:

Unfortunately, the testcase still fails on the __alignof__ (x) != 4
check (regression from 3.0.x and earlier) - this was apparently broken
on gcc HEAD already in Nov 2001. Back into debugger.

Which is of course silly thing to test, because that doesn't
matter for binary compatibility. Lots of __alignof__ for toplevel objects
changed between gcc versions. What matters if its __alignof__ when
embedded in some other structure is correct.

Changing __alignof__ does change binary compatibility in C++ -- it can
result in different templates being instantiated.

That's not a comment on your x86 changes; just a parenthetical statement.

--
Mark Mitchell                mark@codesourcery.com
CodeSourcery, LLC            http://www.codesourcery.com

References:
- [PATCH] C++ ABI fix - bitfield layout on IA-32 (take 2)
  - From: Jakub Jelinek

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