[PATCH 2/2] [ARM] Add support for -mpure-code in thumb-1 (v6m)

[Kyrill Tkachov]

On 1/14/20 1:50 PM, Christophe Lyon wrote:
> On Mon, 13 Jan 2020 at 14:49, Kyrill Tkachov
> <kyrylo.tkachov@foss.arm.com> wrote:
>> Hi Christophe,
>>
>> On 12/17/19 3:31 PM, Kyrill Tkachov wrote:
>>> On 12/17/19 2:33 PM, Christophe Lyon wrote:
>>>> On Tue, 17 Dec 2019 at 11:34, Kyrill Tkachov
>>>> <kyrylo.tkachov@foss.arm.com> wrote:
>>>>> Hi Christophe,
>>>>>
>>>>> On 11/18/19 9:00 AM, Christophe Lyon wrote:
>>>>>> On Wed, 13 Nov 2019 at 15:46, Christophe Lyon
>>>>>> <christophe.lyon@linaro.org> wrote:
>>>>>>> On Tue, 12 Nov 2019 at 12:13, Richard Earnshaw (lists)
>>>>>>> <Richard.Earnshaw@arm.com> wrote:
>>>>>>>> On 18/10/2019 14:18, Christophe Lyon wrote:
>>>>>>>>> +      bool not_supported = arm_arch_notm || flag_pic ||
>>>>>> TARGET_NEON;
>>>>>>>> This is a poor name in the context of the function as a whole.
>>>>>>>> What's
>>>>>>>> not supported.  Please think of a better name so that I have some
>>>>>>>> idea
>>>>>>>> what the intention is.
>>>>>>> That's to keep most of the code common when checking if -mpure-code
>>>>>>> and -mslow-flash-data are supported.
>>>>>>> These 3 cases are common to the two compilation flags, and
>>>>>>> -mslow-flash-data still needs to check TARGET_HAVE_MOVT in addition.
>>>>>>>
>>>>>>> Would "common_unsupported_modes" work better for you?
>>>>>>> Or I can duplicate the "arm_arch_notm || flag_pic || TARGET_NEON" in
>>>>>>> the two tests.
>>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> Here is an updated version, using "common_unsupported_modes" instead
>>>>>> of "not_supported", and fixing the typo reported by Kyrill.
>>>>>> The ChangeLog is still the same.
>>>>>>
>>>>>> OK?
>>>>> The name looks ok to me. Richard had a concern about Armv8-M Baseline,
>>>>> but I do see it being supported as you pointed out.
>>>>>
>>>>> So I believe all the concerns are addressed.
>>>> OK, thanks!
>>>>
>>>>> Thus the code is ok. However, please also updated the documentation for
>>>>> -mpure-code in invoke.texi (it currently states that a MOVT instruction
>>>>> is needed).
>>>>>
>>>> I didn't think about this :(
>>>> It currently says: "This option is only available when generating
>>>> non-pic code for M-profile targets with the MOVT instruction."
>>>>
>>>> I suggest to remove the "with the MOVT instruction" part. Is that OK
>>>> if I commit my patch and this doc change?
>>> Yes, I think that is simplest correct change to make.
>>>
>> Can you also send a patch to the changes.html page for GCC 10 making
>> users aware that this restriction is now lifted?
>>
> Sure. I should have thought of it when I submitted the GCC patch...
>
> How about the attached? I'm not sure about the right upper/lower case
> and <code> markers....
>
> Thanks,
>
> Christophe

commit ba2a354c9ed6c75ec00bf21dd6938b89a113a96e
Author: Christophe Lyon<christophe.lyon@linaro.org>
Date:   Tue Jan 14 13:48:19 2020 +0000

     [arm] Document -mpure-code support for v6m in gcc-10

diff --git a/htdocs/gcc-10/changes.html b/htdocs/gcc-10/changes.html
index caa9df7..26cdf66 100644
--- a/htdocs/gcc-10/changes.html
+++ b/htdocs/gcc-10/changes.html
@@ -417,7 +417,11 @@ a work-in-progress.</p>
    data-processing intrinsics</a> to include 32-bit SIMD, saturating arithmetic,
    16-bit multiplication and other related intrinsics aimed at DSP algorithm
    optimization.
-   </li>
+  </li>
+  <li>Support for <code>-mpure-code</code> in Thumb-1 (v6m) has been
+  added: this M-profile feature is no longer restricted to targets
+  with <code>MOTV</code>. For instance, Cortex-M0 is now
+  supported</li>

Typo in MOVT.
Let's make the last sentence. "For example, <code>-mcpu=cortex-m0</code> now supports this option."

Ok with those changes.
Thanks,
Kyrill

 Â </ul>
  
  <h3 id="avr">AVR</h3>