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Re: [PATCH, PR 45934 4/6] Dynamic type change detection

From: Jason Merrill <jason at redhat dot com>
To: Martin Jambor <mjambor at suse dot cz>
Cc: GCC Patches <gcc-patches at gcc dot gnu dot org>, Richard Guenther <rguenther at suse dot de>, Jan Hubicka <hubicka at ucw dot cz>
Date: Thu, 02 Dec 2010 18:25:28 -0500
Subject: Re: [PATCH, PR 45934 4/6] Dynamic type change detection
References: <20101201201618.861802217@virgil.suse.cz> <20101201201711.231211674@virgil.suse.cz>

On 12/01/2010 03:16 PM, Martin Jambor wrote:

and there are no unions of non-POD types

This is actually no longer true in C++0x.

dynamic types.  It assumes that destructors begin with assignment into
all VMT pointers and that constructors essentially look in the
following way:

1) The very first thing they do is that they call constructors of the
    components (including ancestor sub-objects) that have them.

2) Then VMT pointers of this and all its ancestors is set to new
    values corresponding to the type corresponding to the constructor.

Slight clarification: this happens after calling constructors for base sub-objects and before calling constructors for member sub-objects.

The rest of the writeup all sounds correct.

Jason

Follow-Ups:
- Re: [PATCH, PR 45934 4/6] Dynamic type change detection
  - From: Martin Jambor

References:
- [PATCH, PR 45934 0/6] Devirtualization aware of dynamic type changes
  - From: Martin Jambor
- [PATCH, PR 45934 4/6] Dynamic type change detection
  - From: Martin Jambor

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