Re: [PATCH][GCC][ARM] Implement "arch" GCC pragma and "+<ext>" attributes [Patch (2/3)]

[Kyrill Tkachov <kyrylo dot tkachov at foss dot arm dot com>]

On 15/11/17 15:59, Tamar Christina wrote:
> > -----Original Message-----
> > From: Kyrill Tkachov [mailto:kyrylo.tkachov@foss.arm.com]
> > Sent: Wednesday, November 15, 2017 10:11
> > To: Tamar Christina <Tamar.Christina@arm.com>; Sandra Loosemore
> > <sandra@codesourcery.com>; gcc-patches@gcc.gnu.org
> > Cc: nd <nd@arm.com>; Ramana Radhakrishnan
> > <Ramana.Radhakrishnan@arm.com>; Richard Earnshaw
> > <Richard.Earnshaw@arm.com>; nickc@redhat.com
> > Subject: Re: [PATCH][GCC][ARM] Implement "arch" GCC pragma and
> > "+<ext>" attributes [Patch (2/3)]
> >
> > Hi Tamar,
> >
> > On 10/11/17 10:56, Tamar Christina wrote:
> > > Hi Sandra,
> > >
> > > I've respun the patch with the docs changes you requested.
> > >
> > > Regards,
> > > Tamar
> > >
> > > > -----Original Message-----
> > > > From: Sandra Loosemore [mailto:sandra@codesourcery.com]
> > > > Sent: 07 November 2017 03:38
> > > > To: Tamar Christina; gcc-patches@gcc.gnu.org
> > > > Cc: nd; Ramana Radhakrishnan; Richard Earnshaw; nickc@redhat.com;
> > > > Kyrylo Tkachov
> > > > Subject: Re: [PATCH][GCC][ARM] Implement "arch" GCC pragma and
> > > > "+<ext>" attributes [Patch (2/3)]
> > > >
> > > > On 11/06/2017 09:50 AM, Tamar Christina wrote:
> > > > > Hi All,
> > > > >
> > > > > This patch adds support for the setting the architecture and
> > > > > extensions using the target GCC pragma.
> > > > >
> > > > > #pragma GCC target ("arch=armv8-a+crc")
> > > > >
> > > > > It also supports a short hand where an extension is just added to
> > > > > the current architecture without changing it
> > > > >
> > > > > #pragma GCC target ("+crc")
> > > > >
> > > > > Popping and pushing options also correctly reconfigure the global
> > > > > state as expected.
> > > > >
> > > > > Also supported is using the __attribute__((target("...")))
> > > > > attributes on functions to change the architecture or extension.
> > > > >
> > > > > Regtested on arm-none-eabi and no regressions.
> > This will need a bootstrap and test run on arm-none-linux-gnueabihf (like all
> > arm changes).
> > Your changelog at
> > https://gcc.gnu.org/ml/gcc-patches/2017-11/msg00387.html mentions some
> > arm-c.c changes but I don't see any included in this patch?
> >
> > The other changes look good and in line with what I would expect, but can
> > you please post the arm-c.c changes if there are any?
> Hi Kyrill,
>
> Sorry, I moved this change into another patch that was already committed and forgot
> to remove it from this changelog.
>
> I've also already bootstrapped this and the 3rd patch when you asked for the bootstrap of
> First one.  But I didn't update mail the status to the list.
>
> The correct changelog is
>
> gcc/
> 2017-11-15  Tamar Christina  <tamar.christina@arm.com>
>
> 	PR target/82641
> 	* config/arm/arm.c (arm_valid_target_attribute_rec):
> 	Parse "arch=" and "+<ext>".
> 	(arm_valid_target_attribute_tree): Re-init global options.
> 	(arm_option_override): Make non-static.
> 	(arm_options_perform_arch_sanity_checks): Make errors fatal.
> 	* config/arm/arm_acle.h (__ARM_FEATURE_CRC32): Replace with pragma.
> 	* doc/extend.texi (ARM Function Attributes): Add pragma and target.
>
> gcc/testsuite/
> 2017-11-15  Tamar Christina  <tamar.christina@arm.com>
>
> 	PR target/82641
> 	* gcc.target/arm/pragma_arch_attribute.c: New.
>
> Ok for trunk?

Thanks Tamar.
This is ok for trunk.
Kyrill

> Thanks,
> Tamar
>
> > Thanks,
> > Kyrill
> >
> > > > > Ok for trunk?
> > > > >
> > > > > diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index
> > 8aa443f87fb700f7a723d736bdbd53b6c839656d..18d0ffa6820326ce7badf33001
> > > > b1
> > > > > c6a467c95883 100644
> > > > > --- a/gcc/doc/extend.texi
> > > > > +++ b/gcc/doc/extend.texi
> > > > > @@ -3858,6 +3858,42 @@ Specifies the fpu for which to tune the
> > > > performance of this function.
> > > > >   The behavior and permissible arguments are the same as for the
> > > > > @option{-mfpu=}  command-line option.
> > > > >
> > > > > +@item arch=
> > > > > +@cindex @code{arch=} function attribute, ARM Specifies the
> > > > > +architecture version and architectural extensions to use for this
> > > > > +function.  The behavior and permissible arguments are the same as
> > > > > +for the @option{-march=} command-line option.
> > > > > +
> > > > > +The above target attributes can be specified as follows:
> > > > > +
> > > > > +@smallexample
> > > > > +__attribute__((target("@var{attr-string}")))
> > > > > +int
> > > > > +f (int a)
> > > > > +@{
> > > > > +  return a + 5;
> > > > > +@}
> > > > > +@end smallexample
> > > > > +
> > > > > +where @code{@var{attr-string}} is one of the attribute strings.
> > > > This example doesn't illustrate anything useful, and in fact just
> > > confuses
> > > > things by introducing @var{attr-string}.  Please use an actual valid
> > > attribute
> > > > here, something like "arch=armv8-a" or whatever.
> > > >
> > > > Also, either kill the sentence fragment after the example, or be
> > > careful to
> > > > add @noindent before it to indicate it's a continuation of the
> > > > previous paragraph.
> > > >
> > > > > +
> > > > > +Additionally, the architectural extension string may be specified
> > > > > +on its own.  This can be used to turn on and off particular
> > > > > +architectural extensions without having to specify a particular
> > > architecture
> > > > version or core.  Example:
> > > > > +
> > > > > +@smallexample
> > > > > +__attribute__((target("+crc+nocrypto")))
> > > > > +int
> > > > > +foo (int a)
> > > > > +@{
> > > > > +  return a + 5;
> > > > > +@}
> > > > > +@end smallexample
> > > > > +
> > > > > +In this example @code{target("+crc+nocrypto")} enables the
> > > > > +@code{crc} extension and disables the @code{crypto} extension for
> > > > > +the function @code{foo} without modifying an existing
> > > > > +@option{-march=} or
> > > > @option{-mcpu} option.
> > > > > +
> > > > >   @end table
> > > > >
> > > > >   @end table
> > > > -Sandra