From: Ian Lance Taylor <iant@google.com>
To: Hei Chan <structurechart@yahoo.com>
Cc: "gcc-help@gcc.gnu.org" <gcc-help@gcc.gnu.org>
Subject: Re: __sync_bool_compare_and_swap() With a Pointer
Date: Mon, 19 Nov 2012 05:42:00 -0000 [thread overview]
Message-ID: <CAKOQZ8z0wCPyidYQJePtZCJvbaQB59qVe6ETmW4b4brJybC+Gg@mail.gmail.com> (raw)
In-Reply-To: <1353301824.76156.YahooMailNeo@web165005.mail.bf1.yahoo.com>
On Sun, Nov 18, 2012 at 9:10 PM, Hei Chan <structurechart@yahoo.com> wrote:
>
> According to http://gcc.gnu.org/onlinedocs/gcc-4.1.1/gcc/Atomic-Builtins.html, __sync_bool_compare_and_swap() supports int, long, long long, and their unsigned counterparts, and GCC will allow any integral scalar or pointer type that is 1, 2, 4 or 8 bytes in length.
>
> I wonder in what situation the pointer type won't be 1, 2, 4 or 8 bytes in length. Let's say I am running on a 64-bit Intel CPU.
On a 64-bit Intel CPU pointer types will always be either 4 or 8 bytes
(4 bytes if using x32).
Remember that GCC supports many different targets. In any case the
sentence does not imply that there will ever be a pointer type that is
not 1, 2, 4 or 8 bytes (though of course there will be if GCC ever
supports a 128-bit machine). The sentence also refers to integral
types, and GCC supports integral types larger than 8 bytes on some
processors, e.g., __int128_t on x86_64.
Ian
prev parent reply other threads:[~2012-11-19 5:42 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-19 5:10 Hei Chan
2012-11-19 5:42 ` Ian Lance Taylor [this message]
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