Re: [RFC, patch] New attribute to create target clones

[Evgeny Stupachenko <evstupac at gmail dot com>]

You can't apply both 'ctarget' and 'target' attributes to a function.
The patch uses same target specific methods to create dispatcher and
target clones.

On Fri, Jul 31, 2015 at 1:30 AM, Andrew Pinski <pinskia@gmail.com> wrote:
> On Thu, Jul 30, 2015 at 3:19 PM, Evgeny Stupachenko <evstupac@gmail.com> wrote:
>> Hi All,
>>
>> The patch enables new attribute 'ctarget',
>> The attribute force compiler to create clones of a function with the attribute.
>>
>> For example:
>> __attribute__((ctarget("avx","arch=slm","arch=core-avx2","default")))
>> int
>> foo ()
>>
>> will create 3 clones of foo() optimized for corresponding targets and
>> replace all foo() calls with ifunc resolver.
>> The patch include new tests for the feature.
>>
>> Currently default ctarget means that foo() will be optimized with
>> current compiler options and target.
>> The other option is to switch target to target specific minimum (like
>> target x86-64). Is it better?
>>
>> What do you think about attribute name? 'ctarget' is short but not
>> informative. Other variants are 'target_clones', 'targets'...
>
> How does this interacts with Function Multiversioning
> (https://gcc.gnu.org/onlinedocs/gcc-5.2.0/gcc/Function-Multiversioning.html)?
>
> Thanks,
> Andrew Pinski
>
>>
>> Below is ChangeLog. Attached patch passed make check on x86.
>>
>> Thanks,
>> Evgeny
>>
>> 2015-07-31  Evgeny Stupachenko  <evstupac@gmail.com>
>>
>> gcc/
>>         * Makefile.in (OBJS): Add multiple_target.o.
>>         * multiple_target.c (make_attribute): New.
>>         (create_dispatcher_calls): Ditto.
>>         (expand_target_clones): Ditto.
>>         (ipa_target_clone): Ditto.
>>         * passes.def (pass_target_clone): New ipa pass.
>>         * tree-pass.h (make_pass_target_clone): Ditto.
>>
>> gcc/c-family
>>         * c-common.c (handle_ctarget_attribute): New.
>>         * (c_common_attribute_table): Add handle_ctarget_attribute.
>>         * (handle_always_inline_attribute): Add check on ctarget attribute.
>>         * (handle_target_attribute): Ditto.
>>
>> gcc/testsuite
>>         * gcc.dg/mvc1.c: New test for multiple targets cloning.
>>         * gcc.dg/mvc2.c: Ditto.
>>         * gcc.dg/mvc3.c: Ditto.
>>         * gcc.dg/mvc4.c: Ditto.
>>         * gcc.dg/mvc5.c: Ditto.
>>         * gcc.dg/mvc6.c: Ditto.
>>         * gcc.dg/mvc7.c: Ditto.
>>         * g++.dg/ext/mvc1.C: Ditto.
>>         * g++.dg/ext/mvc2.C: Ditto.
>>         * g++.dg/ext/mvc3.C: Ditto.