Re: [Patch] ARM define atomic_exchange_acq/atomic_exchange_rel to __atomic_exchange_n

[Dinar Temirbulatov <dtemirbulatov at gmail dot com>]

Hi,
Here is updated version of change. Ok to commit?
                thanks, Dinar.

On Mon, Sep 2, 2013 at 7:08 PM, Joseph S. Myers <joseph@codesourcery.com> wrote:
> On Mon, 2 Sep 2013, Dinar Temirbulatov wrote:
>
>> Hi,
>> Another version of change, I added
>> atomic_compare_and_exchange_val_acq/atomic_compare_and_exchange_val_rel
>> and atomic_compare_and_exchange_bool_acq/atomic_compare_and_exchange_boot_rel
>> defenitions and also for gcc-4.7 and higher in the case of unsupported
>> atomic compare and swap operation, it uses the kernel helper inlines.
>> Tested on arm a9 with no new regressions. Ok to commit?
>> Oh, sorry. I missed to attach the change. Here it is.
>
> For subsequent patch revisions, please note there should be an extra space
> after "#" for preprocessor directives inside #if conditionals, one per
> level of #if nesting (other than toplevel multiple-inclusion guards) -
> which means that if conditioning existing code, you need to adjust
> directives inside that code.
>
> This patch appears to have too much duplication.  For example, you
> duplicate the definition of __arm_assisted_compare_and_exchange_val_32_acq
> - but that should not need any extra conditionals at all (beyond the
> existing #ifndef __arm_assisted_compare_and_exchange_val_32_acq), there's
> no reason ever not to define it.  Similarly, you duplicate
> __arch_compare_and_exchange_val_64_acq, but with proper #if structure
> there should only need to be one copy of the version that uses
> __arm_link_error.
>
> What I think you should aim for is that each definition, or small group of
> definitions, uses conditionals in the form
>
> #if __GNUC_PREREQ (4, 7) && defined __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
> /* Version using __atomic_*.  */
> #elif defined __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
> /* Version using __sync_*.  */
> #else
> /* Version using __arm_assisted_*.  */
> #endif
>
> with cases omitted if not useful for that particular macro (this may
> include some macros not being defined at all in some cases).  So don't
> insert any global conditionals affecting all the existing definitions at
> all - look at each block of conditionals and add a third case as needed,
> along with any new macros (again with conditionals in that form) that are
> appropriate.
>
> Where you use abort () in some definitions, use __arm_link_error ()
> instead, like for the existing definitions.
>
> --
> Joseph S. Myers
> joseph@codesourcery.com

Attachment: arm_atomic7.patch
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