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

[Tamar Christina <Tamar dot Christina at arm dot com>]

> -----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

> 
> 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