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Re: C++ ABI Issues
- From: Mark Mitchell <mark at codesourcery dot com>
- To: Jamie Lokier <egcs at tantalophile dot demon dot co dot uk>
- Cc: "gcc at gcc dot gnu dot org" <gcc at gcc dot gnu dot org>
- Date: Mon, 26 Aug 2002 23:43:00 -0700
- Subject: Re: C++ ABI Issues
--On Tuesday, August 27, 2002 03:17:31 AM +0100 Jamie Lokier
Mark Mitchell wrote:
G++ incorrectly packs D::i2 into the four bits of tail-padding in
This is not only an ABI divergence, but also an optimization issue.
G++ generates a copy-constructor for B that performs the bit-masking
operations required to copy only the bitfield at the end of B, which
is more expensive than copying the entire word.
Is there any scenario where the bit-masking is actually necessary?
It is necessary in an assignment operator.
Mark Mitchell firstname.lastname@example.org
CodeSourcery, LLC http://www.codesourcery.com