Re: [PATCH 18/18] arm64: lto: Strengthen READ_ONCE() to acquire when CLANG_LTO=y

From
Arnd Bergmann <arnd@arndb.de>
Date
2020-07-01 10:59:58
Also in
linux-alpha, lkml, virtualization
Reply to
Will Deacon, 2020-07-01
On Wed, Jul 1, 2020 at 12:19 PM Will Deacon [off-list ref] wrote:
On Tue, Jun 30, 2020 at 09:25:03PM +0200, Arnd Bergmann wrote:
quoted
On Tue, Jun 30, 2020 at 7:39 PM Will Deacon [off-list ref] wrote:
Once we make gcc-4.9 the minimum version,
this could be further improved to

       __auto_type __x = &(x);
Is anybody working on moving to 4.9? I've seen the mails from Linus
championing it, but I thought there was a RHEL in support that people
might care about?
I don't think there was a serious discussion about it so far, and
we only just moved to gcc-4.8.

I think moving to gnu11 (gcc-4.9 or clang) instead of gnu99 has other
benefits as well, so we may well want to do it anyway when something
else comes up.

For __auto_type(), we could do it like

#if (clang or gcc-4.9+)
#define auto_typeof(x) __auto_type
#else
#define auto_typeof(x) typeof(x)
#endif

which could be used in a lot of macros.

     Arnd

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Thread (58 messages) 58 messages, 12 authors, last reply 2020-07-08
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