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Re: immediate strings #2
From: |
Ken Raeburn |
Subject: |
Re: immediate strings #2 |
Date: |
Mon, 28 Nov 2011 19:57:23 -0500 |
On Nov 28, 2011, at 17:25, Andreas Schwab wrote:
> Stefan Monnier <address@hidden> writes:
>
>> Not that it's relevant to Emacs, but I don't know which part of the
>> C standard would force a C compiler to layout all unions at an
>> "addressable" offset.
>
> 6.7.2.1#13
Well, I think Stefan's technically right... the "as-if" rule lets the compiler
get away with a lot, if it can analyze enough of the program to figure out that
it wouldn't make a difference to the semantics ("no one will notice", as Stefan
put it). For example, gcc can make some variables that have their addresses
taken still live in registers anyways. But few or none of the compilers we
care about right now will do that when dealing with structure layouts and
multiple source files as in Emacs; they'll implement something close enough to
the abstract machine description in the standard that the union would have to
be addressable.
Ken
- immediate strings #2, Dmitry Antipov, 2011/11/28
- Re: immediate strings #2, Stefan Monnier, 2011/11/28
- Re: immediate strings #2, Ken Raeburn, 2011/11/28
- Re: immediate strings #2, Andreas Schwab, 2011/11/28
- Re: immediate strings #2, Stefan Monnier, 2011/11/28
- Re: immediate strings #2, Andreas Schwab, 2011/11/28
- Re: immediate strings #2,
Ken Raeburn <=
- Re: immediate strings #2, Andreas Schwab, 2011/11/29
- Re: immediate strings #2, Ken Raeburn, 2011/11/29
- Re: immediate strings #2, Andreas Schwab, 2011/11/29
- Re: immediate strings #2, Ken Raeburn, 2011/11/30
Re: immediate strings #2, Paul Eggert, 2011/11/28
- Re: immediate strings #2, Stefan Monnier, 2011/11/28
- Re: immediate strings #2, Dmitry Antipov, 2011/11/28
- Re: immediate strings #2, Paul Eggert, 2011/11/29
- Re: immediate strings #2, Dmitry Antipov, 2011/11/30
- Re: immediate strings #2, Paul Eggert, 2011/11/30