Hi,

Currently GCC is happy to use LDRD to perform a 64bit load on ARMv7-R,
as shown by the testcase on this patch. However, LDRD is only atomic
when LPAE extensions is available, which they are not for ARMv7-R. This
commit solve the issue by introducing a new feature bit to distinguish
LPAE extensions instead of deducing it from div instruction
availability.

ChangeLog entries are as follow:

*** gcc/ChangeLog ***

2017-03-22  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	PR target/80082
	* config/arm/arm-protos.h (FL_LPAE): Define macro.
	(FL_FOR_ARCH7VE): Add FL_LPAE.
	(arm_arch_lpae): Declare extern.
	* config/arm/arm.c (arm_arch_lpae): Declare.
	(arm_option_override): Define arm_arch_lpae.
	* config/arm/arm.h (TARGET_HAVE_LPAE): Redefine in term of
	arm_arch_lpae.

*** gcc/testsuite/ChangeLog ***

2017-03-22  Thomas Preud'homme  <thomas.preudhomme@arm.com>

	PR target/80082
	* gcc.target/arm/atomic_loaddi_10.c: New testcase.
	* gcc.target/arm/atomic_loaddi_11.c: Likewise.

Is this ok for gcc-5-branch?

Best regards,

Thomas

On 06/04/17 14:05, Ramana Radhakrishnan wrote:
> On Mon, Mar 27, 2017 at 12:15 PM, Thomas Preudhomme
> <thomas.preudhomme@foss.arm.com> wrote:
>> Hi,
>>
>> Currently GCC is happy to use LDRD to perform a 64bit load on ARMv7-R,
>> as shown by the testcase on this patch. However, LDRD is only atomic
>> when LPAE extensions is available, which they are not for ARMv7-R. This
>> commit solve the issue by introducing a new feature bit to distinguish
>> LPAE extensions instead of deducing it from div instruction
>> availability.
>
>
> Ok but with the testsuite fix that I just approved,  please also fix
> in gcc-5 branch.
>
> Thanks,
> Ramana
>
>>
>> ChangeLog entries are as follow:
>>
>> *** gcc/ChangeLog ***
>>
>> 2017-03-22  Thomas Preud'homme  <thomas.preudhomme@arm.com>
>>
>>         PR target/80082
>>         * config/arm/arm-protos.h (FL_LPAE): Define macro.
>>         (FL_FOR_ARCH7VE): Add FL_LPAE.
>>         (arm_arch_lpae): Declare extern.
>>         * config/arm/arm.c (arm_arch_lpae): Declare.
>>         (arm_option_override): Define arm_arch_lpae.
>>         * config/arm/arm.h (TARGET_HAVE_LPAE): Redefine in term of
>>         arm_arch_lpae.
>>
>> *** gcc/testsuite/ChangeLog ***
>>
>> 2017-03-22  Thomas Preud'homme  <thomas.preudhomme@arm.com>
>>
>>         PR target/80082
>>         * gcc.target/arm/atomic_loaddi_10.c: New testcase.
>>         * gcc.target/arm/atomic_loaddi_11.c: Likewise.
>>
>>
>> Testing: bootstrapped for -march=armv7ve and testsuite shows no regression.
>>
>> Is this ok for gcc-6-branch?
>>
>> Best regards,
>>
>> Thomas