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.

Patches attached for reference.

ChangeLog entries:

*** gcc/ChangeLog ***

2017-06-20  Thomas Preud'homme  <thomas.preudhomme@arm.com>

     Backport from mainline
     2017-05-04  Prakhar Bahuguna  <prakhar.bahuguna@arm.com>

     * 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/ChangeLog ***

2017-06-20  Thomas Preud'homme  <thomas.preudhomme@arm.com>

     Backport from mainline
     2017-05-04  Prakhar Bahuguna  <prakhar.bahuguna@arm.com>

     gcc/testsuite/
     * gcc.target/arm/fpscr.c: New file.


Best regards,

Thomas