Re: [Qemu-devel] [PATCH v1 7/9] tests/tcg: add float_madds test to multiarch

[Richard Henderson <richard.henderson@linaro.org>]

On 9/17/19 5:00 PM, Alex Bennée wrote:
>>> +    add_f32_const(0x8p-152);
>>> +    add_f32_const(0x8p-152);
>>> +    add_f32_const(0x8p-152);
>>
>> Why are you adding 3 of the same?
> 
> To replicate the 1841491 test case where the same number is used for
> a/b/c

Then we really ought to be more explicit about that.

You're not doing full permutations on the sets of numbers, so does incrementing
a random index really test what you intended?

>>> +#if defined(__arm__)
>>> +                r = __builtin_fmaf(a, b, c);
>>> +#else
>>> +                r = __builtin_fmaf(a, b, c);
>>> +#endif
>>
>> Eh?
> 
> Ahh I was going to hardcode the arm madd instruction in as the builtin
> wasn't expanding. I tried setting -march in the CFLAGS but that didn't
> trigger it either on my buster arm-hf compiler. Any ideas how to get the
> compiler to do the right thing?

I think you want -mfpu=neon-vfpv4.


r~