Re: Subnormal float support in armv7(with -msoft-float) for intrinsics

[Umesh Kalappa <umesh dot kalappa0 at gmail dot com>]

Hi Nagy,

Please  help us with your comments on the attached patch for the issue
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86512)

Thank you and waiting for your inputs on the same.
~Umesh

On Fri, Jul 13, 2018 at 1:22 PM, Umesh Kalappa <umesh.kalappa0@gmail.com> wrote:
> Thank you and issue  raised at
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86512
>
> ~Umesh
>
> On Thu, Jul 12, 2018 at 9:33 PM, Szabolcs Nagy <szabolcs.nagy@arm.com> wrote:
>> On 12/07/18 16:20, Umesh Kalappa wrote:
>>>
>>> Hi everyone,
>>>
>>> we have our source base ,that was compiled for armv7 on gcc8.1 with
>>> soft-float and for following input
>>>
>>> a=0x0010000000000000
>>> b=0x0000000000000001
>>>
>>>   result = a - b ;
>>>
>>> we are getting the result as "0x000ffffffffffffe" and with
>>> -mhard-float (disabled the flush to zero mode ) we are getting the
>>> result as ""0x000fffffffffffff" as expected.
>>>
>>
>> please submit it as a bug report to bugzilla
>>
>>
>>> while debugging the soft-float code,we see that ,the compiler calls
>>> the intrinsic "__aeabi_dsub" with arm calling conventions i.e passing
>>> "a" in r0 and r1 registers and respectively for "b".
>>>
>>> we are investigating the routine "__aeabi_dsub" that comes from libgcc
>>> for incorrect result  and meanwhile we would like to know that
>>>
>>> a)do libgcc routines/intrinsic for float operations support or
>>> consider the subnormal values ? ,if so how we can enable the same.
>>>
>>> Thank you
>>> ~Umesh
>>>
>>

Attachment: 86512.patch
Description: Binary data