Re: [PATCH, GCC/ARM, Stage 1] Rename FPSCR builtins to correct names

[Thomas Preudhomme <thomas.preudhomme@foss.arm.com>]

Hi Christophe,

On 23/06/17 20:10, Christophe Lyon wrote:
> Hi Thomas,
> 
> On 23 June 2017 at 17:48, Thomas Preudhomme
> <thomas.preudhomme@foss.arm.com> wrote:
>> Hi Kyrill,
>>
>>
>> On 10/04/17 15:01, Kyrill Tkachov wrote:
>>>
>>> Hi Prakhar,
>>> Sorry for the delay,
>>>
>>> On 22/03/17 10:46, Prakhar Bahuguna wrote:
>>>>
>>>> The GCC documentation in section 6.60.8 ARM Floating Point Status and
>>>> Control
>>>> Intrinsics states that the FPSCR register can be read and written to
>>>> using the
>>>> intrinsics __builtin_arm_get_fpscr and __builtin_arm_set_fpscr. However,
>>>> these
>>>> are misnamed within GCC itself and these intrinsic names are not
>>>> recognised.
>>>> This patch corrects the intrinsic names to match the documentation, and
>>>> adds
>>>> tests to verify these intrinsics generate the correct instructions.
>>>>
>>>> Testing done: Ran regression tests on arm-none-eabi for Cortex-M4.
>>>>
>>>> 2017-03-09  Prakhar Bahuguna  <prakhar.bahuguna@arm.com>
>>>>
>>>> gcc/ChangeLog:
>>>>
>>>>      * gcc/config/arm/arm-builtins.c (arm_init_builtins): Rename
>>>>        __builtin_arm_ldfscr to __builtin_arm_get_fpscr, and rename
>>>>        __builtin_arm_stfscr to __builtin_arm_set_fpscr.
>>>>      * gcc/testsuite/gcc.target/arm/fpscr.c: New file.
>>>>
>>>> Okay for stage 1?
>>>
>>>
>>> I see that the mistake was in not addressing one of the review comments
>>> in:
>>> https://gcc.gnu.org/ml/gcc-patches/2014-04/msg01832.html
>>> properly in the patch that added these functions :(
>>>
>>> This is ok for stage 1 if a bootstrap and test on arm-none-linux-gnueabihf
>>> works
>>> fine
>>> I don't think we want to maintain the __builtin_arm_[ld,st]fscr names for
>>> backwards compatibility
>>> as they were not documented and are __builtin_arm* functions that we don't
>>> guarantee to maintain.
>>
>>
>> How about a backport to GCC 5, 6 & 7? The patch applied cleanly on each of
>> these versions and the testsuite didn't show any regression for any of the
>> backport when run for Cortex-M7.
>>
> 
> Three's a problem with GCC-5:
>      gcc.target/arm/fpscr.c: unknown effective target keyword
> `arm_fp_ok' for " dg-require-effective-target 4 arm_fp_ok "
> 
> Indeed arm_fp_ok effective-target does not exist in the gcc-5 branch.

Oh no. I remember not seeing anything but I can indeed see this with 
compare_tests from the sum file I save after each testing. Alright, what is done 
is done, working on a patch now.

Best regards,

Thomas