Re: [PATCH] arm: [testsuite] fix lob tests for -mfloat-abi=hard

[Andrea Corallo <andrea.corallo@arm.com>]

"Richard Earnshaw (lists)" <Richard.Earnshaw@arm.com> writes:

> On 26/11/2020 13:53, Andrea Corallo via Gcc-patches wrote:
>> Hi all,
>> 
>> I'd like to submit the following simple patch to clean some Low Loop
>> Overhead test failing on hard float configurations.
>> 
>> lob2.c and lob5.c are failing with: "'-mfloat-abi=hard': selected 
>> processor lacks an FPU".
>> 
>> lob3.c and lob5.c got "-mfloat-abi=soft and -mfloat-abi=hard may not
>> be used together".
>> 
>> Okay for trunk?
>> 
>> Thanks
>>   Andrea
>>   
>> 
>
> I think it would be better to try to do this with suitable
> require-effective-target rules (or something similar).  Forcing options
> should generally be a last resort and in particular using -mfpu should
> really be avoided as we're trying to move away from that.
>
> diff --git a/gcc/testsuite/gcc.target/arm/lob4.c
> b/gcc/testsuite/gcc.target/arm/lob4.c
> ...
> -/* { dg-skip-if "avoid conflicting multilib options" { *-*-* } {
> "-marm" "-mcpu=*" } } */
> +/* { dg-skip-if "avoid conflicting multilib options" { *-*-* } {
> "-marm" "-mcpu=*" "-mfloat-abi=hard" } } */
>  /* { dg-options "-march=armv8.1-m.main -mthumb -O3 --save-temps
> -mfloat-abi=soft" } */
>  /* { dg-require-effective-target arm_softfloat } */
>
> Why is the effective target arm_softfloat not solving this particular
> conflict?

Good point,

I see is because we are defining __SOFTFP__ when compiling with
'-march=armv8.1-m.main+mve -mfloat-abi=hard'.

This sounds like a bug to me, correct?

If that's correct either we should consider also TARGET_HAVE_MVE and
TARGET_HAVE_MVE_FLOAT into arm_cpu_builtins when deciding for the
__SOFTFP__ definition or account them for our internal
TARGET_SOFT_FLOAT.  I guess the first is less invasive.

I'll come up with a patch unless I'm told that this is not a bug.

  Andrea